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287 Cards in this Set
- Front
- Back
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Order that senses are lost following a spinal anesthetic:
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ATPTPMVP: Autonomics, Temperature, pain, touch, pressure, motor, vibration, proprioception
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What type of diuretics do you want to give if your patient is hypernatremic?
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renal tubular diuretics (ie. Thiazides which inhibit Na+ reabsorption)
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In a typical patient, why would serum Na be less than 135?
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Relative water excess versus Na loss (volume overload)
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What are causes of Na loss?
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loss of GI secretions with vomiting/diarrhea, certain diuretic tx., adrenal insufficiency (d/t lo aldosterone), alcohol consumption (d/t inhibition of ADH)
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Signs and symptoms of hyponatremia:
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hypotention
tachycardia oliguria hemoconcentration CNS symptoms: lethargy, coma, seizures |
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At what point do CNS symptoms of hyponatremia typically develop?
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Na <120
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_______ changes or elevation of K is usually asymptomatic
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Chronic; acute changes are detrimental
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What are the S/S or consequences of acute K elevation?
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prolonged P-R
widening QRS peaked T wave all moving toward onset of V-tach |
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How do you treat K elevation?
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CaCl, NaHCO3, dextrose and insulin
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it is recommended that any elective surgery be cancelled until K+ is
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<5.5
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Alkalosis or beta-2 agonist tx for asthma or premature labor can result in:
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Hypokalemia
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What are potential causes of hyponatremia?
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with diuretic therapy, vomiting, diarrhea, NG sxn, alkalosis, or beta-2 agonist therapy
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Skeletal muscle weakness may be a sign of:
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hypokalemia
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What are potential complications of hypokalemia? How might this manifest on EKG?
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skeletal muscle weakness
decreased myocardial contractility increased automaticity producing cardiac dysrhythmias prolonged PR interval prolonged QT flattening Twave |
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What type of ventilation must be avoided in a patient who you are concerned about hyperkalemia?
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Hyperventilation
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What are common causes of intraop fluid loss?
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Sequestration of fluid in soft tissue injury
Surgical trauma (blood loss) intraop Infection GI losses (NG sxn, vomiting, diarrhea) Third space loss intraop |
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How might volume deficit manifest in a patient?
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hypoperfusion
Tachycardia (be careful, may not see in beta-blocked pt.) Hypotension with decreased CVP Diminished heart tones |
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How much Hexpan can you give? What is the major concern with this synthetic colloid?
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20 ml/kg or 1000 ml; affects coagulation
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How much blood volume must you lose before transfusion is appropriate?
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1/3 total blood volume (although patient specific)
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What is the estimated blood volume for an adult male? Female?
Obese patient? |
Adult male: 70 ml/kg
Adult female: 65 ml’kg Obese patient: 60 ml/kg |
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What is the formula for allowable blood loss?
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Estimated blood volume x(Hct (initial)-target)/Initial Hct
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What conditions might limit a patient's ability to tolerate anemia (and therefore make you transfuse at a higher Hct)?
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Hyperthermia
Hyperthyroidism Sepsis Pregnancy Abnormal Hemoglobin (or Recently transfused) Acute anemia (limited 2,3 DPG compensation) Impaired oxygenation Ongoing or imminent blood loss Limited ability to increase cardiac output Coronary artery disease(Myocardial dysfunction B adrenergic blockade Inability to redistribute CO) Post cardiopulmonary bypass Left shift of O2 Hb curve |
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How much does 1 unit of blood generally increase Hgb?
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One unit=lg/dl increase in Hgb
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How much does 1 unit of platelets increase plt count?
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One unit platelets increases count 5,000-7,000K
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How much does one unit of FFP increase clotting factors?
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2%
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____ may cause clotting of PRBCs
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Calcium
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______ solutions may cause hemolysis of PRBCs
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Glucose solutions
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Why do you give FFP?
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PT/PTT > 1.5 times normal
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What is the most common type of blood transfusion reaction?
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Febrile reaction
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What are S/S of blood transfusion reaction?
What do you do? |
Chills
Dyspnea Flushed skin Rash Hypotention Hgb in plasma and urine (seen in hemolytic reaction- wrong blood type) Stop blood! Send back to blood bank and treat symptoms |
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Patients may exhibit what pH abnormality following several units of PRBC's?
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metabolic acidosis- preservatives cause H ion increase
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Old blood (in transfusions) can have a high ______ concentration, and a low ____ concentration
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Potassium; low 2,3 DPG concentration (left shift in oxyhemoglobin dissociation curve)
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Blood transfusion might cause _____calcemia
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Hypocalcemia (calcium binds to citrate)
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What effect might blood transfusion have on immune system?
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Immunosuppressive (PRBC's less effect than plasma)
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Stored blood must always be administered through at least a _____ filter
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170 micron filter
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A decrease of body temp. as small as_____degree C may induce shivering postop.
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0.5-1 degree C
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How much does shivering increase O2 consumption?
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As much as 400%.
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Blood must be _____ when given intraoperatively
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Warmed- to prevent hypothermia and post-op shivering
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What techniques can be employed to conserve blood?
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Preoperative autologous donations
Acute normovolemic hemodilution Intraoperative blood salvage Postoperative blood salvage Pharmacological agents: 1 Erythropoietin 2 DDAVP 3 Antifibrinolytics |
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What measurements decrease with age (geriatrics)
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BMR
Standard cell water Glomerular filtration rate Vital capacity Maximal breathing capacity Cardiac index (Decline 1-1.5% per year starting at 30 years of age) |
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Transient confusion or disorientation may persist postoperatively in ______ of the elderly.
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25%
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Elderly adults might require ___in NDMR requirements.
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slight increase
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What autonomic changes are seen in the elderly population?
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- Reduced adrenoreceptor and end-organ
sensitivity to peripheral beta-agonists. -Chronic elevation of norepi levels -Disruption of autonomic baroreceptor and thermoregulatory homeostasis. -Reduced autonomic responses to hypoxia and hypercarbia |
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What myocardial changes are seen in the elderly?
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Decreased inotropic and chronotropic
response to beta-adrenergic stimulation. -Decreased ventricular compliance -Decreased intrinsic heart rate and increased atrial ectopy |
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Older adults have a greater reliance on ____load
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Preload
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What changes are seen in the lung function of geriatric patients?
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- Minimal change in FRC
- Increased RV -Decreased vital capacity -Increased small airway closure |
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Elderly individuals have a higher % of fat _______
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where lipid soluble drugs can sequester
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What factors affect the action of drugs in the elderly?
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Absorption: Variable
Distribution Small lean body mass Increased adipose tissue Reduced total body water Decreased plasma albumin Variable changes in protein binding Decreased membrane permeability Decreased cardiac output and splanchnic blood flow |
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What factors effect metabolism and clearance of drugs in the elderly?
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Metabolism
Reduced liver mass Reduced hepatic flow Reduced enzyme induction by alcohol and cigarettes Elimination Reduced renal plasma flow Reduced glomerular filtration |
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Drug considerations in the elderly
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Assume some pre-existing mental impairment which could be unmasked or exacerbated by sedative, opioid, or anesthetic drug administration.
Use short acting sedatives and hypnotics. Do not over sedate with MAC or regional Avoid prophylaxis for aspiration or N&V Avoid drugs associated with delirium Avoid scopolamine, atropine, droperidol |
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Do the elderly routinely require prophylaxis for GERD/aspiration?
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No
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Use _____ in elderly if reasonable doses of anesthetic agents are being used.
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non anesthetic drugs to control intraoperative hypertension
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Treat _____ as a drug which ma not be required in elderly patients prior to spinal or epidural anesthesia
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volume
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What are the S/S of postoperative delerium
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Disorder of Cognitive function
Thinking Perception Memory: Short term Difficulty concentrating < visual and motor speed Sleep disturbance Fluctuating levels of consciousness Altered psychomotor activity |
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What are three assumptions about all trauma patients?
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Cervical spine injury
Full stomach Hypovolemia |
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LeFort I
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horizontal fracture of lower maxilla that produces a mobile palate
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LeFort II
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triangular extension of type I , involves two fracture lines from orbits to base of tongue. Maxilla is displaced backward and may be free floating
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LeFort III
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transverse fracture through the orbits. A complete separation of maxilla from craniofacial skeleton
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S/S Basilar Skull Fracture
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raccoon eyes, bleeding from ears/nose, flat face deformity, xray confirmation
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S/S Cervical Blunt Trauma
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may be missed in initial assessment. S/S- hoarse, muffled voice, dyspena
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, the administration of anesthetics and MRs may result in a trauma patient may result in
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soft tissue collapse, causing an irreversible airway obstruction
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Shock
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circulatory failure leading to inadequate vital organ perfusion and O2 delivery.The most common cause of shock is hypovolemia
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S/S shock
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tachycardia, hypotension, cold, clammy (r/t vasoconstriction), decreased UOP and mental status
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Massive Blood Transfusion is defined as:
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Replacement of more than 1x the patient's blood volume
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What problems are encountered with Massive blood transfusion
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Dilutional Thrombocytopenia- most common cause of bleeding disorder after massive transfusions. Occurs because platelets in stored blood are destroyed.
Factors 5 & 8 are decreased to 30% of normal levels pH of stored blood decreases to 6.65 (met. Acidosis) Hyperkalemia (K levels is stored blood range from 7-30 meq/L) Hypocalcemia (preservative citrate binds Calcium) |
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Trauma patient may only tolerate ____ with O2 for intubation
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Scopolomine 0.4 mg, muscle relaxant and O2 before intubation
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Etomidate is good for:
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Has minimal or absent cardiac depressant effects compared to TPL.
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Etomidate disadvantages:
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irritation/phlebitis to injected vein, extrapyramidal movements, n/v post-op, Adrenal Suppression has been reported following a single dose. S/S- unresponsive hypotension. Tx- hydorcortisone 100mg.
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Which inhaled agent is generally avoided in trauma patients?
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N2O
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Which trauma patients might you want to avoid use of sux with? What are other considerations with this drug?
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Hyperkalemia- avoid in patients who have sustained burns, crush injuries, spinal cord injuries- absolutely contraindicated 24 hrs after incident, up to 2 years;
Increases ICP, IOP, MH trigger |
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Burn pt’s show a resistance ______
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non-depolarizers and may require significantly higher doses because of an increased number of extrajunctional receptors
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What is the hardest CN to anesthetize? If a patient retains a sense intraoperatively, what will it be?
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CN VIII (auditory)
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Greatest amount of heat loss is by
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Radiation (60%)
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How can hypothermia be prevented/treated in trauma patients?
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increased ambient room temp., cover exposed skin with Bair/plastic on head, warm IVF,low flows and humidifiers, warm irrigation by surgeon.
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In head injured/trauma patients, main goal is to prevent any decrease in O2 supply to the brain by preventing
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decreased BP, hypoxemia, anemia, increased ICP (CPP=MAP-ICP), acidosis and hyperglycemia
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Greatest detriment to injured brain is _____, followed by _____
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Hypotension, Hypoxia
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Damage to the spinal cord at T1-T4 can cause:
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bradycardia d/t loss of cardiac accelerators
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What is the best drug to use to treat the sympathectomy caused by spinal cord injury?
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Phenylephrine
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In a trauma patient, you see EKG changes (ischemia), may see elevated cardiac enzymes, what might you suspect?
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Cardiac contusions
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What are S/S of pericardial effusion
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Beck’s Triad: distended neck veins, hypotension, muffled heart sounds.
Also may see: Pulsus Paradoxis- decreased BP by 10 mmHg with inspiraiton. Electrical Alternans- alternating big and small QRS complex. Narrow Pulse Pressure |
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Shoulder pain and rigid abdomen might suggest:
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Liver or splenic laceration
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What will you observe in CO poisioning in regards to oxygentation?
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The pulse ox saturation looks falsely high because it can’t tell the wavelength difference between O2 from CO on Hb, but ABG O2 sat is lower
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How much fluid do you give a burn victim according to the Parkland formula?
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give crystalloid 4 cc/kg/TBSA % burned. (½ volume given in initial 8 hrs with the remaining ½ over 16 hrs
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What are the preferred induction agents in burn patients?
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Ketamine and etomidate are preferred because of CV stability for pt. when volume status is not known
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The most comfortable temperature for a burn patient is
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100 degrees F (38 C)
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What are risk factors for reaction to contrast?
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Shellfish or iodine allergy
Previous reaction Environmental allergies CHF Use of Beta Blockers High-anxiety state Interleukin-2 |
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What agent might you want to premedicate with to prevent secretions and asystole when performing ECT
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Robinul
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______ occurs in patients taking lithium for 15 years or more
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Hypothyroidism
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______ is desired to lower seizure threshold for ECT
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Hypocarbia
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Clincal symptoms of aspiration pneumona/pneumonitis
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Hypoxemia
Inc PIP Dyspnea, bronchospasm, laryngospasm Adventitious lung sounds CXR: Infiltrates in dependent lobes |
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Why is aspiration such a high risk under anesthesia?
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Unconsciousness impairs protective reflexes
Both lower and upper esophageal sphincter tone reduced by anesthesia Upper airway reflexes continue to be significantly impaired for 2 hours after recovery from anesthesia. Electrolyte abnormalities and hyperglycemia impair gastric motility |
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Injury caused by aspiration is related to ____ and _____
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low pH and high volume
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Indications for RSI
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Full Stomach
GI Bleeding Intestinal Obstruction Severe GERD Pregnancy |
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How much force is applied to perform Sellick Maneuver (cricoid pressure)
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7-10 lbs
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Do you ventilate the patient between giving NMB and intubation when performing an RSI?
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NO!
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When do you release cricoid pressure following RSI?
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Only when placement has been confirmed!
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When do you start giving cricoid pressure during and RSI?
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As soon as you give meds, before consciousness is lost
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What do you do if your patient vomits on induction?
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Head Tilt to Side or Down
Immediate Suctioning Immediate Intubation Suction ETT Before First Breath NG Tube ABGs, PEEP |
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What three classes of drugs can increase the risk of regurgitation by reducing gastric motility.
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alcohol, anticholinergics, or opioids
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Prevention of aspiration sequelae requires attention to what three variables?
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Regurgitation
Aspiration Caustic composition of material |
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What causes the larges increases in IOP?
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Vomiting or coughing
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Epineurium
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Easy permeable, connective tissue layer covering one or more bundles of axons. Also contains nutritional blood vessels of larger nerves.
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MINIMUM BLOCKING CONCENTRATION
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Lowest Possible Concentration of LA Needed to Block Impulse
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How do most local anesthetics work?
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Cause cells to be unable to reach threshold potential by blocking Na channels
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Motor fibers take approximately ______ concentration of local anesthesia than do sensory fibers to be blocked
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twice the concentration
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Motor fibers are located _____ compared to sensory fibers
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Further inside the nerve (LA has to diffuse further to reach motor fibers)
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You need ______ concentration of highly lipid soluble local anesthetics
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Less concentration to acheive same effect
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pKa
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The pH at which the ionized and nonionized forms are present in equal amounts
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Speed of onset is _____ to pKa
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Inversely proportional
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Do local anesthetics work faster or slower in infected areas? Why?
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Slower- infected areas are relatively acidotic and therefore local anesthetics are more ionized and work slower
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How does adding bicarb affect local anesthetics?
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Speeds onset- makes the environment that LA is injected into more "like" the LA
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You need ______ concentration of highly lipid soluble local anesthetics
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Less concentration to acheive same effect
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pKa
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The pH at which the ionized and nonionized forms are present in equal amounts
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Speed of onset is _____ to pKa
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Inversely proportional
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Do local anesthetics work faster or slower in infected areas? Why?
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Slower- infected areas are relatively acidotic and therefore local anesthetics are more ionized and work slower
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How does adding bicarb affect local anesthetics?
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Speeds onset- makes the environment that LA is injected into more "like" the LA
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Local anesthetics have this type of pH and _____ hydrogen ions
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alkaline, accept hydrogen ions
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The further a basic drug (LA) moves from its pKa towards an acid, the _______ it will be
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More ionized
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With local anesthetics, the _____ determines the speed of onset, and the ______ determines the duration of effect
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pKa- onset
protein binding- duration |
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I think I can please everyone but suzie smith- how is this applicable?
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IV, tracheal, intercostal, caudal, paracervical, epidural, brachial plexus, sciatic, subcutaneous- The rate of systemic absorption is proportionate to the vascularity of the site of injection; if docs are injecting lots of local around the trachea, you should be concerned with potential systemic effect/toxicity
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How are amide local anesthetics metabolized? Is this fast or slow?
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have to travel all the way to liver for metabolism, so slow process
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How are ester local anesthetics metabolized? Is this fast or slow?
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Broken down by pseudocholinesterase; much faster, so shorter half-life
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What id a metabolite of prilocaine?
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PABA- potential allergen
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What are potential downsides of priolcaine?
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PABA is metabolite, can lead to methemoglobin production
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Patients with _____ deficiencies might have prolonged reactions to local anesthethics
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Pseudocholinesterase
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How are amide local anesthetics metabolized? Is this fast or slow?
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have to travel all the way to liver for metabolism, so slow process
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How are ester local anesthetics metabolized? Is this fast or slow?
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Broken down by pseudocholinesterase; much faster, so shorter half-life
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What id a metabolite of prilocaine?
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PABA- potential allergen
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What are potential downsides of priolcaine?
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PABA is metabolite, can lead to methemoglobin production
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Patients with _____ deficiencies might have prolonged reactions to local anesthethics
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Pseudocholinesterase
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Where should local anesthetics containing vasoconstrictors not be used?
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The nose, the toes,, and the hose
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Using vasoconstrictors in local anesthetics has what effect?
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Increases the duration and enhances the block
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If a patient has an allergy to one type of local anesthetic, what can you do? What do you have to be careful of?
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Use the other class of LA, be careful regarding preservatives that could be allergy culprit in both classes of LA
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A patient is tachycardic following LA administration. What do you think could cause this? Is this an allergy?
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Could be from epi in LA and therefore not an allergy
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LA toxicity in the CNS progresses from _____ to _______
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Circumoral numbness to seizures
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What is the maximum single dose of Lidocaine that you can give? Bupivicaine?
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Lido: 5-7mg/kg
Bupiv: 3mg/kg |
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Direct neural injury d/t local anesthetics: TRI- what is this and what are the symptoms?
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Transient Radicular Irritation-
Moderate to severe pain in lower back, butt, and posterior thighs Appears w/i 24 hours Recovery w/i 1 week Most assoc. with lido (any conc.), less with bup/tet Exaggerated by nerve stretch or vasoconstrictor cells |
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Direct neural toxicity caused by local anesthetics: CES- what does this mean? What are the symptoms?
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Cauda Equina Syndrome
Diffuse injury across lumbrosacral plexus Sensory anesthesia Bowel/bladder dysfunction Paraplegia |
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Cardiac toxicity d/t local anesthetics is a result of ____
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cardiac sodium channels becoming blocked; reduces myocardial contractility
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What is the most cardiac toxic local anesthetic?
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Bupivicaine
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What is the prototypical local anesthetic to which all others are compared?
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Lidocaine
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What is the duration of action of lidocaine? How fast is the onset?
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Rapid onset, duration 60-120 min
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Bupivicaine is good because _____; it has a _____ onset and _____ duration
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It provides analgesia with less motor block; slow onset, long duration (240-480 min)
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Ropivicaine works similarly to Bupivicaine, but ______
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Is less cardiotoxic
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EMLA is a topical combination of :
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Lidocaine and prilocaine (remember prilocaine produces methemoglobin as byproduct during metabolism)
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Cocaine is an _____ local anesthetic, but not used because of ______
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ester; not used because of CNS stimulating effect, addictive properties, and vasoconstrictive properties
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What is the downside of 2-chloroprocaine? Is it an amide or and ester?
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can produce permanent neurological damage from additives used to maintain its stability
Ester |
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When applied to intact skin, local anesthetics _____ provide anesthetic action, but in skin damaged by sunburn______
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Do not provide anesthesia in intact skin, but do in skin damaged by sunburn
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Local anesthetics have a _____ when given IV
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Narrow therapeutic index
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Local anesthetics can offer what benefit in DL?
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Suppress cough, ICP, and HTN in response to DL
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What percent concentration of lidocaine or prilocaine do you use to perform a Bier Block?
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0.5%
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What are the advantages of regional anesthesia?
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Very good muscle relaxation
Very good postoperative analgesia Increased bowel motility Sympathetic block provides prophylaxis against thromboembolism Suitable for outpatient procedures Cost effective Easy and safe monitoring |
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What nerves does regional anesthesia not block?
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Vagus and Phrenic Nerves
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You should not administer regional anesthesia above the _____ level
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T4-6
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What are some potential side effects of regional anesthesia?
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Nausea
Vomiting Hiccup Pain Hypotension |
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Contraindications to regional anesthesia
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Patient Refusal
Coagulation disorders, anticoagulation therapy Sepsis Local infections at injection site Immune deficiency Shock, severe decompensated hypovolemia Acute cerebral or spinal cord disease Increased intracranial pressure Hypersensitivity to local anesthetic agents CV disease of myocardial, ischemic or valvular origin requiring loss of sensation above T6. |
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The spinal cord extends from the _____ to _____
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Foramen Magnum to L1-L2; Lumbar and Sacral Nerves Form Cauda Equina
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Whose law explains why it takes longer for an epidural to take effect than a SAB?
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Fick's Law- anesthetic has to diffuse across the dura and into the CSF
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What are the landmarks for dermatomes?
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T4- nipple line (possible cardioaccelerator blockade), T10 umbilicus (sympathetic blockade limited to legs), Pinky finger- C8 (getting too close to phrenic nerve innervating diaphragm, all cardioaccelerators blocked), L1 crease of thigh if patient on all fours
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The iliac crest is the landmark for:
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The L4-L5 space
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What level block is needed for a cesarean section?
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T4
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What level can you perform a spinal block?
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Below L1-L2 (end of solid cord)
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Spinal anesthesia blocks ______ fibers first, followed by ________
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small, unmyelinated sympathetic fibers first, followed by larger myelinated sensory fibers, then motor fibers
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What is the significance of blocking the proprioceptive sense with a spinal anesthetic?
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Makes the patient think they can't breathe, even though they can
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If you perform a block above the level of T5, what might you see? Why?
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Bradycardia- unopposed parasympathetic activity (cardioaccelerators at T1-T4 blocked)
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Patients receiving regional anesthesia might have _____ blood loss because _____
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Less blood loss, vessels dilated
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Patients receiving regional anesthesia might not have an ______ response to pain
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Adrenocortical response to pain
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What is the purpose of the obturator when performing a spinal anesthetic?
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Prevents you from carving out fat, etc. as you go through structures
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In the subarachnoid space, you should have ______ of CSF
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Free flowing
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Parasthesias indicate
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You are TOO CLOSE to a nerve root- probably not midline; DO NOT INJECT INTO NERVE ROOT
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Baricity
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Density of LA solution/Density of CSF
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Hyperbaric local anesthetic solutions: where does the anesthetic go?
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Settles to the most dependent parts of the subarachnoid space
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With spinal anesthetic, the _____ determines how far the block travels, and the ______ determines the effect
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Dose determines distance, concentration determines effect
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What is the most common baricity of local anesthetics for spinal anesthesia>?
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Hyperbaric
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Hypobaric solutions are _____ than CSF and ______ in the spinal canal
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Lighter, rise to non-dependent areas
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______ solutions are good for surgeries taking place at L1 or below
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Isobaric- stays right where you want it
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Sympathetic block is _______ than sensory
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2 dermatomes higher
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Motor block is ______ than sensory
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2 dermatomes lower
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If you perform a block that knocks out sensory stimuli at T10, what levels will you see a sympathetic and motor block?
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Sympathetic block will be two dermatomes higher, so at T8, and motor block will be two dermatomes lower, so T12
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Use of small catheters for continuous spinal anesthesia is related to development of ____________
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Cauda Equina syndrome (esp with 5% lido solutions)
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What is postdural puncture headache?
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"spinal headache" worst in occipital region of head and neck or in frontal region that is caused by loss of CSF and therefore traction is caused on meningeal vessels and nerves. Tends to be better when laying and worse when sitting, may also have diplopia
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What factors decrease the incidence of postdural puncture headache?
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With Age
Use of Rounded Point Needle Use of Smaller Gauge Needle Needle Inserted Parallel Rather Than Perpendicular to Dural Fibers |
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What are the treatments for postdural puncture headache?
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Bed rest
Binder Analgesics Hydration Caffeine (500mg IV) Blood Patch |
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Treatment for a total spinal includes:
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Protect and support airway and respirations, support blood pressure with vasopressors
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Your patient has received a spinal anesthetic and is now nauseus, agitated, and hypotensive with difficulty breathing. What is one thing you might suspect?
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Spinal has traveled too high and is now a total spinal
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In an average sized person, what is the average distance from the skin to the ligament of flavum?
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4 cm in 50% of people. 4-6 cm in 80% of people
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What are the contents of the epidural space?
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Fat
Connective tissue Lymph Internal and external vertebral venous plexuses Roots of spinal nerves |
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The epidural space size _____ as you go up the spinal cord
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Decreases- more of a potential space in the upper spinal column
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What does sacral sparing mean?
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S1-S2 is hardest to block- these nerves might be "spared" from the action of the anesthetic (check the dermatome- outside aspect of foot)
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Once an epidural catheter has passed through the end of the needle, what do you want to avoid?
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DO NOT WITHDRAW CATHETER; can cause catheter to shear off in the back d/t sharp edges of spinal needle
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With the loss of resistance technique, how do you know when you have entered the epidural space?
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NS will inject easily (loss of resistance)
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Should you have CSF return to confirm that you are in the epidural space?
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No, if you get CSF flow, you are in the subarachnoid space
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What is the purpose of a test dose of local anesthetic when placing an epidural?
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Small dose of anesthetic injected to test whether the catheter is epidural, subarachnoid, or venous. Dose is normal dose for spinal, but very low dose for epidural, so if patient shows signs of spinal block following test dose (motor block, thick sensory block) then you know you are in the subarachnoid space. If you see systemic effects, you suspect that you are in the venous system (increased HR, increased BP, tinnitus, circumoral numbness, metallic taste in mouth)
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A slow drip from a spinal needle when placing an epidural:
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Probably NS, fast drip or stream is probably CSF
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What is the benefit of a spinal over an epidural? Vice versa?
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Spinal is faster onset, more reliable, but has a defined endpoint; epidural is slower onset, but titrateable and longer lasting; combined spinal/epidural gives you the best of both worlds for C-sections and ortho cases
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To do a combined spinal/epidural, first you _____, then you _____.
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First you place an epidural, then you place a spinal needle through the dura and arachnoid mater, inject spinal dose, and then pull spinal needle out and proceed with threading epidural catheter
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What are the risks associated with epidural catheter placement?
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Accidental dural puncture, intravascular absorption (d/t large volumes given), hypotension (slower onset than spinal), total spinal, nerve injury
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Extrajunctional receptor number is ______ in response to neural activity
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suppressed
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ACh is metabolized by __________
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acetylcholinesterase
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Acetylcholinesterase uses hydrolysis to breakdown ACh to
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acetic acid & choline
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How quickly does Ach break down acetylcholine in the NMJ?
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<15ms
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Succinylcholine acts as an ________ at acetylcholine receptors
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agonist
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Because sux is not broken down by acetylcholinesterase in the NMJ, the junction __________
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stays depolarized longer, essentially causing refractory period during which muscle cannot contract again
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Phase I block
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Depolarizing block; Decreased contraction in response to a single twitch stimulation
Decreased amplitude but sustained response to continuous stimulation TOF ratio > 0.7 1st twitch 70 % > than 4th twitch Absence of posttetanic facilitation |
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Phase II Block
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a prolonged end-plate depolarization can cause changes in the ACh receptor which causes the block to resemble that of a NDMR; TOF ratio < 0.7
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What can cause a phase II block from succinylcholine?
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Single large dose of > 2mg/kg
Repeated doses Prolonged continuous infusions Antibiotics: Vanc, gent, tobra, strepto |
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Nondepolarizing NMB work as _____ ath the Ach receptor
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Acts as a competitive antagonist of the ACh receptor
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What can cause the number of extrajunctional receptors to be upregulated?
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Degeneration
(CVA, SCI, MS) Disease muscle atropy Direct muscle trauma Thermal trauma Infection Prolonged use of muscle relaxants |
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What can cause downregulation of extrajunctional receptors?
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Myasthenia Gravis
Anticholinesterase overdose Chronic cholinesterase inhibition Organophosphate poisoning |
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Succinylcholine: use, dose, and duration
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to provide prompt relaxation for intubation (esp. RSI), without a prolonged period of relaxation
Dose: 0.5 – 1 mg/kg (kids 2 mg/kg IV) Onset 30-60 sec Duration: 3 – 5 min |
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SCh is hydrolyzed by_____________
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plasma cholinesterase (pseudocholinesterase)
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Where is pseudocholinesterase produced? What is the significance of this?
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Produced in the liver, can have decreased synthesis in liver failure, and can therefore have prolonged duration of succinylcholine
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What is the potential complication of succinylcholine administration in patients that might have upregulated receptors?
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Hyperkalemia
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How long after a burn is succinylcholine safe to use? How long must it be avoided?
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First 24 hours- then contraindicated for up to 2 years (differing sources say different things- some say until completely recovered from burn)
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What is a less dangerous complication of succinylcholine administration? How can it be attenuated?
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Myalgias from uncoordinated muscle contraction- not related to observable strength of fasiculation, can pretreat with 1/10 dose of non-depolarizer
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Complications of succinylcholine:
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Hyperkalemia
Myalgia Myoglobinuria Arrrhythmias Increased IOP Increased ICP Increased intragastric pressure (can pretreat with nondepolarizer) Masseter muscle rigidity Malignant hyperthermia anaphylaxis (histamine release) Prolonged relaxation in cases of plasmacholinesterase deficiency |
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What test can be performed to test the functional capability of psuedocholinesterase?
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Dibucaine testing
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A patient who is heterozygous for pseudocholinsterase deficiency will have a dibucaine number of :
Homozygous: |
Heterozygous: 60
Homozygous: 20 |
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The onset of NDMRs activity at the vocal cords is more _____ but less _____ than activity at peripheral muscles
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More rapid, less intense
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The ______ is the best indicator of laryngeal muscle blockade
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Orbicularis oculi
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Where should TOF electrodes be placed to give you the most accurate indication of laryngeal muscle blockade?
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On the eye versus on the wrist
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What muscle groups are lost first when using a nondepolarizing muscle blocker? How does this proceed?
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Small, rapid muscles lost first and regained last (eyes, digits), trunk and abdominal muscles lost next, and then intercostal muscles and diaphragm (which is regained first during recovery period)
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ED95
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dose of muscle relaxant that produces 95% of a single twitch response
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Intubating dose is typically ____ times the ED95
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2x
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Clearance, distribution, and elimination of nondepolarizing neuromuscular blocking agents is influenced by:
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age, volatile anesthetics, & renal and hepatic disease
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What factor does not significantly influence the clearance & distribution of NDMRs
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Protein binding
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What percentage of receptors must be blocked by neuromuscular blocking agents to suppress a twitch>?
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70%
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How do non-depolarizing NMB agents work>?
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Competes with ACh at the alpha subunits of a postjunctional NMJ receptor
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What are characteristics specific to nondepolarizing NMB agents?
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Decreased twitch response to a single stimulus
Unsustained response (fade) during continuous stimulation TOF ratio of <0.7 Potentiation of other NMDRs Antagonism by anticholinesterase drugs |
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What drugs may alter the effect of NDNMB drugs?
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Volatile anesthetics produce dose dependent increase of the magnitude & duration NDMRs
Aminoglycoside antibiotics enhance blockade Small doses of local anesthetics can enhance blockade Magnesium enhances NDMR (by decreasing prejunctional release of ACh) Patients taking phenytoin are resistant to NDMRs Cyclosporine prolongs the duration of NDMRs Ganglionic Blocking Drugs (trimethaphan) can delay onset and prolong duration by decreasing muscle blood flow |
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What conditions alter the typical effects of NDNMB drugs?
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Hypothermia prolongs the duration of organ metabolized NDMRs due to decreased hepatic activity
Hypothermia slows down the metabolism Hoffman eliminated NDMRs Burns of >30% BSA cause increased resistance to NDMRs (occurs at 10 days, peaks at 40, declines at 60) Administering 2 NDMRs can cause a synergistic effect Paresis can show a resistance to NDMRs |
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Pancuronium: onset, duration, fun facts
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Onset 3-5 minutes
Duration: 60-90 minutes 80% excreted unchanged in urine, metabolized in liver, blocks muscarinic receptor at the SA node and causes vagal blockade and SNS activation (increased HR, CO, MAP) |
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Vecuronium: Onset, duration, fun facts
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Onset 2-3 min
Duration 30-40 min No cardiovascular effects even when given in high doses; Renal dysfunction decreases clearance & increases duration |
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Rocuronium: Onset, duration, fun facts
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Onset: 1-2 min
Duration: 20-35 min Can be used for modified RSI at 3-4 times the ED95 dose, however the duration will be lengthened Doesn’t stimulate histamine release, no CV effects |
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Atracurium: onset, duration, fun facts
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Onset 2-3 minutes
Duration 35 - 50 minutes Highly protein-bound; organ independent elimination (Hoffman's elimination); Acidosis slows elimination Alkalosis increases elimination HISTAMINE RELEASE (pretreat with antihistamine; patients on H2 blockers can have exaggerated Histamine 1 release) Laudonosine is metabolite (can cause CNS stimulation and hypotension) |
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Cistaracurium: onset, duration, fun facts
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Onset 3-6 minutes
Duration 40 – 55 minutes Hofmann elimination (77%) renal clearance (16%) Does not affect HR or BP RARE allergic reactions, but SEVERE when present ↑Elimination in elderly because of ↑Vd (↓muscle mass, fat, etc) Laudanosine is primary metabolite (5X less than atracurium) |
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ACh is synthesized in the nerve terminal by
|
acetyltrasferase
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Administration of anticholinesterase causes increased ACh at the NMJ due to __________
|
inhibition of acetylcholinesterase
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Can you reverse depolarizing NMB agents?
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No, instead, administering cholinesterase inhibitors increases Phase I blocks by making more Ach available and intensifying depolarization and also reduces hydrolysis of succinylcholine by pseudocholinesterase
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Can you reverse a block that produces no twitches to stimulation?
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No, you can't outcompete when the receptors are blocked that fully- must have at least one twitch on TOF
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Neostigmine: mechanism, dose, duration, fun facts
|
binds to acetylcholinesterase (causing increase of Ach at NMJ); dose 0.05 mg/kg; onset at 5-10 min and lasts up to 1 hour; DOES NOT CROSS BBB, but does cross placenta and can cause fetal bradycardia
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You are caring for a pregnant woman and have given neostigmine to reverse your NMB. Which antimuscarinic should you give along with this? Which should you avoid?
|
do not give with Robinul which cannot cross placenta- instead give pregnant women atropine to prevent fetal bradycardia
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Pyrodostigmine: duration, dose, fun facts
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0.4 mg/kg
Onset 10-15 minutes (20% as potent as neostigmine) Duration: 2 hours Should be paired with Robinul so that antimuscarinic does not wear off before pyridostigmine |
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Edrophonium: onset, dose, fun facts
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Onset 1-2 minutes, dose 0.5-1 mg/kg, shortest acting cholinesterase inhibitor, low doses should not be used because NMB could outlast low dose edrophonuium
Used in determining cholingergic crisis- in myasthenia gravis, when too much Ach is floating around, this medication will make symptoms worse |
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Edrophinium should be paried with:
|
atropine d/t onset of action; if using with robinul, robinul should be given several minutes before edrophonium
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|
Physostigmine's usefulness is limited because
|
lipid solube and penetrates CNS; can be used to treat atropine or scopalamine toxictity (central anticholinergic toxicity)
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Robinul is typically given to reverse ______ and ______
Atropine is usually given to reverse ______ |
neostigmine and pyridostigmine for robinul;
atropine reverses edrophonium |
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|
Drugs that cause histamine release:
|
Sux, Atricurium, Mivacurium, Morphine, Propofol, thiopental
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|
|
Echothiphate eye drops cause
|
Decreased pseudocholinesterase; increased duration of succinylcholine for 3-7 weeks after DC
|
|
|
S/S of central anticholinergic syndrome
|
Mad as a hatter: delirium and agitation
Hot as a hare: febrile Red as a beet: flushed Dry as a bone: anhidrosis and xerostomia |
|
|
The 5 and dime reflex
|
Trigeminal afferent limb
Vagal efferent limb - pressure on eye causes stimulation of the afferent trigeminal nerve which causes a reflexive activation of the 10th cranial (vagus) nerve resulting in bradycardia and dysrhythmias |
|
|
How do you treat symptomatic oculocardiac reflex
|
Remove pressure or traction
Reflex fatigues with time Atropine 10-20 mcg/kg or Glycopyrolate |
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|
Incidence and severity of the oculocardiac reflex increases with
|
hypoxia and hypercapnia
|
|
|
In open globe procedures, _____ cannot be used, and _____ must remain low
|
Succinylcholine cannot be used, IOP must remain low
|
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|
Your patient is receiving opthalmic anesthesia and has received a retrobulbar block. You notice progressive neurologic symptoms. What do you suspect?
|
Brain stem anesthesia
|
|
|
Patients undergoing surgery for strabismus have an increased likelihood of ______
|
MH- avoid succs in this population
|
|
|
Why are patients undergoing surgery at increased risk for corneal abrasion?
|
loss of tear production and protective eyelid closure
|
|
|
Signs of corneal abrasion?
What do you do? |
Sensation of foreign body
2 Tearing 3 Photophobia 4 Pain 5 Conjunctivitis Immediate optho consult (in PACU) |
|
|
Patients undergoing ENT procedures are more likely to experience:
How can this be prevented/attenuated? |
PONV
Pretreatment with multiple modality antiemetics Decompress stomach Limit use of opioids |
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|
Can you use N20 for ear tube placement?
|
NO! Can cause rupture or displace graft
|
|
|
What three steps must you take when MD is using throat packs?
|
Chart when goes it
Chart when it comes out Put reminder somewhere that you will see it |
|
|
O2 concentrations during laser procedures
|
Must be maintained less than 40%; no N2O use
|
|
|
What position should patients be placed in following tonsillectomy?
|
head lower than hip, lateral.
In this position, blood will drain out and not cause irritation of vocal cords or accumulate in stomach. |
|
|
What steps can you take to avoid/limit airway fires?
|
Choose flame-retardent ETT (Laser flex tube or norton tube)
Inflate cuff with saline or methylene blue Keep FiO2 <30% Avoid N2O (supports combustion) Wet drapes Have sterile H2O readily available |
|
|
What do you do if an airway fire occurs?
|
Stop ventilation
Interrupt O2 supply Removed ETT Douse field with H2O Remove drapes if on fire Look for debris in airway and suction Resume ventilation by mask or reintubate Diagnose injury and provide therapy Monitor patient Administer steroids Administer antibiotics and ventilatory support |
|
|
Afferent blood supply to liver:
Efferent supply: |
Portal Vein and Hepatic artery: afferent
hepatic vein: efferent |
|
|
The liver receives _____ of the CO. What percentage of this is from the portal vein?
|
25% of CO, 70% of supply is via portal vein (30% d/t hepatic artery)
|
|
|
Inhaled anesthetics and regional decrease Hepatic blood flow by ____ %
|
< HBF 20-30%
|
|
|
What are the 5 important functions of the liver?
|
Albumin Synthesis
Bilirubin Metabolism Carbohydrate Metabolism Clotting Factor Production Drug Metabolism |
|
|
Best measurement of hepatic synthetic function
|
Albumin level
|
|
|
Total Bilirubin can be elevated d/t
|
a massive transfusion
absorption large hematomas hemolysis |
|
|
Conjugated bilirubin can be elevated d/t
|
hepatocellular disease
b disease of small bile duct c congential syndromes d obstruction extrahepatic biliary ducts |
|
|
Albumin correllates with:
|
wound healing
|
|
|
Presence of Australian Antigen indicates
|
active viral hepatitis
|
|
|
If a patient is jaundiced, they should receive _____ pre-op
|
Vit K for 3 days pre-op
|
|
|
S/S liver disease
|
Malaise, Dyspepsia, Weight Loss
Spider Nevi Portal Hypertension Esophageal Varices H2O Retention, Hyponatremia and Oliguria Ascites Flapping Tremor of Hand |
|
|
The three most serious potential complications of liver disease
|
Encephalopathy
Ascites GI Bleed |
|
|
Portal hypertension causes:
|
Development of Collateral Vessels
Portal Obstruction Splenomegaly Hepatorenal Syndrome Portal-sytemic Shunting |
|
|
What intraoperative factors might lead to hepatic injury/
|
ALTERED BY:
Systemic Pressure Hepatic Venous Pressure Splanchnic Vascular Resistance Blood May Have Inadequate O2 Content Increased Requirement |
|
|
Anesthetic complications that you might expect with alcoholism:
|
Coagulapathies
Glucose problems Smoking related issues Anemia Thrombocytopenia |
|
|
What volatile agent is theoretically the best at preserving hepatic blood flow
|
Isoflurane
|
|
|
Chronic alcoholics are likely to have ______ anesthetic requirements
|
Increased volatile
|
|
|
A patient who is acutely inebriated with alcohols is likely to have:
|
Prone to Aspiration
Hypotension Hypoglycemia Hypothermia Reduced Anesthetic Requirements |
|
|
S/S acute alcohol withdrawal
|
Autonomic Hyperactivity
Tremors Tachycardia Diaphoresis Fever Anxiety Insomnia Hallucinations |
|
|
When does alcohol withdrawal start? End?
|
Starts at 6-24 hours, ends after 45 hours
|
|
|
seizures in alcohol withdrawal start at:
|
8-24 hours and occur within a 6 hour period. Highest mortality in 1st 24 hours
|
|
|
Advanced liver disease impairs elimination, prolongs half-life, and > clinical effects of
|
morphine, meperdine, alfentanil, vecuronium, rocuronium, mivacurium, BNZ, and dexmedotimidine…adjust dose accordingly!
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