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90 Cards in this Set
- Front
- Back
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What is hypotension defined as in MAP (direct or indirect) and Systolic (Doppler)?
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MAP < 65 mmHg
Systolic < 80 mmHg |
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With hypotension, will an animal have a fast or slow HR?
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fast - tachycardia
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What is the number one cause of hypotension in young and otherwise healthy animals?
the second cause? |
anesthetic drugs
blood loss during surgery |
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What are the mechanisms of hypotension during anesthesia?
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-decreased preload
-decreased myocardial contractility -decreased vascular resistance |
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Give examples of preexisting problems that can exacerbate the hypotensive event in a patient?
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-hypovolemia
-shock -cardiomyopathy (esp DCM) -valvular heart disease -dysrhythmias, hypothyroidism -hypoxemia - very bad -addisonian crisis |
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What is the FIRST LINE treatment for hypotension?
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turn DOWN the vaporizor
turn UP the fluids |
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If there is hypotension associated with blood loss, what is the treatment plan?
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-replace 3 times the estimated loss with crystalloids
-if > 10% blood volume or PCV 25 or less, consider blood |
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What is the SECOND LINE treatment for hypotension?
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sympathomimetic drugs
- dopamine - dobutamine - ephedrine - vasopressin |
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What is the definition of hypoxemia?
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-partial pressure of O2 in arterial blood (PaO2) < 60mmHg
-pulse oximeter reading (SpO2) < 90% |
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What can hypoxemia lead to in veterinary patients?
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cardiac arrest
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What are causes of hypoxemia?
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-decreased inspired O2 concentration
-hypoventilation -ventilation-perfusion (V/Q) mismatch -shunt or venous admixture -diffusion barrier -veterinarians |
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What is the number one cause of anesthetic DEATH in vet patients?
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failure to maintain a patent airway leading to hypoxemia
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What factors can cause hypoxemia?
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-unrecognized extubation
-disconnection -aspiration -kinked endotracheal tube -failure to turn on oxygen -closed pop off valve -empty oxygen cylinder -overdose of anesthetic drugs |
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How do you manage hypoxemia?
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-determine if it is resp or cardiac arrest
-100% oxygen -check airway - ET tube -manual ventilation -patient to machine |
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What is the definition of hypercarbia?
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-arterial CO2 (PaCO2) or end tidal CO2 > 50 mmHg
-normal in the awake animal is 35-45 mmHg |
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What do anesthetic drugs do to the central respiratory system?
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depress it in a dose dependent fashion
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Why is hypercarbia usually not detrimental to the patient?
When would it be detrimental to the patient? |
because of sympathomimetic effects
-exception - patients with increased intracranial pressure |
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What does hypercarbia do to the patient?
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-increased systolic BP
-increased pulse pressure -increased SV, myocardial contractility and HR -decreases systemic vascular resistance |
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What are clinical signs of hypercarbia?
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-tachycardia
-hypertension -shallow breathing with increased rate and decreased tidal volume too light or painful -respiratory acidosis (below 7.2) |
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What is most hypercarbia a result of?
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decreased elimination rather than increased production in most cases
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What is the treatment for hypercarbia?
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-control ventilation
-decrease anesthetic concentration -sigh patients periodically |
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How are all inhalent anesthetic agents myocardial depressants?
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in a dose dependent fashion
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What are possible effects on the heart with anticholinergics?
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-sinus tachycardia
-2 degree AV block |
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What are possible effects on the heart with phenothiazines?
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sinus tachycardia
-alpha-1 adrenergic blockade |
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What are possible effects on the heart with opiods?
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-bradycardia
-2 degree AV block |
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What are possible effects on the heart with barbituates?
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-tachycardia
-bigeminy |
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Is the pause on inhalation or exhalation with sinus arrythmias?
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inhalation
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What is the definition of sinus bradycardia in a small and large dog and a cat?
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Lg breed dog is <60bpm
Sm breed dog is <70bpm Cat is < 100-120 bpm |
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What is the most common dysrhythmia seen under general anesthesis?
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sinus bradycardia
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What are the contributing factors to sinus bradycardia?
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increased PNS activity: increased vagal tone
-decrease in SNS input |
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table
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la mesa
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What is the definition of sinus tachycardia?
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-lg breed dog - >160 bpm
-small breed dog >180 bpm -cat >220 bpm |
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What are contributing factors to sinus tachycardia?
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-sympathetic response to surgery
-pain -hypovolemia -shock -hypercarbia -uncontrolled disease processes |
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What happens when HR becomes so high that there is inadequate time for ventricular filling?
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-decreased CO
-decreased BP |
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How do you treat sinus tachycardia?
pain hypovolemia hypercarbia disease process |
pain - increase vaporizor/analgesics
hypovolemia - fluids hypercarbia - ventilation disease process - treat prior to anesthesia |
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Where do Premature ventricular contractions originate?
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below the AV node and AV junction
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What is the most common ventricular dysrhythmia seen during general anesthsia?
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Premature ventricular contractions
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What does the ECG look like with VPCs?
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P waves not associated with a QRS complex.
QRS complexes are wide and bizarre |
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What are causes of PVCs?
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-trauma patients with myocardial bruising
-electrolyte imbalances -acid/base disturbances -hypoxemia -hypothermia -bradycardia |
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How do you treat PVCs?
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find underlying cause and treat only if the hemodynamic stability of patient is compromised
-lidocain - IV or CRI -oxygen and ventilation -analgesics |
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What is the definition of hypothermia?
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temps < 38 C (100.5 F)
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What are clinical signs of hypothermia?
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-cold peripheral extremities
-pink areas look blue -MM may be blanched |
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When is the greatest temperature loss during anesthesia?
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in the first hour
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How much does MAC decrease per 1 degreee C in body temp?
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5-7%
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What happens when body temp drops below 32 C (89.6 F)?
below 28 C (82.4F) |
no shivering
cardiac arrest |
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What does shivering do?
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increase metabolic oxygen 200-300%
-increases CO and minute ventilation |
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What happens when there is too rapid emergence from anesthesia?
What happens when there is too much opiod? |
disorientation
-dysphoria |
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What drug could you give for recovery excitement?
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low dose of acepromazine
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Why are local anesthetics used?
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PRE-EMPTIVE PAIN MANAGEMENT
-to decrease MAC of inhalant -quicker recoveries -lower overall pain scores -patient safety |
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What is the process of pain processing?
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1 - transduction
2 - transmission to sensory nerves 3 - Modulation in spinal cord 4 - Perception in cerebral cortex -local anesthetics block all but perception |
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What are esters hydrolysed by?
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plasma cholinesterase
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Are esters or amides assoicated with PABA and therefore allergies?
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Esters
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What organ are amides metabolized by?
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hepatic
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How do local anesthetics work?
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are lipophilic and bind to receptor sites in the Na channel to prevent or impede Na ion movement
(Na channel blockers) -electrical impulses are reduced and nerve conduction is blocked |
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What determines local anesthetic potency?
What determines local anesthetic duration? |
lipid solubility
protein binding |
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Do local anesthetic provide adequate analgesia for inflammed tissues?
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no
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Tell me which of the pair is more easily blocked"
-sympathetic or sensory -sensory or motor -myelinated or non -small or large -fast or slow |
sympathetic
senosry myelinated small faster |
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What is more important with local blocks - volume or concentration?
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volume
1 node of ranvier - 30% blocked 2 nodes - 70% blocked 3 nodes - 100% blocked |
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Which fibers are blocked first with a local block?
last? |
B
alpha and beta |
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What is the order the following are lost from first to last?
touch, pain, cold, pressure, motor, warmth |
pain> cold > warmth > touch > joint > deep > pressure > motor
-motor is the last thing to go and the first thing to come back |
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What are 3 examples of esters?
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(1) procaine - short acting, non-irritating (Novicaine)
(2) - Benzocaine - topical, wounds (3) Proparacaine - eye |
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What are 3 examples of amides?
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(1) lidocaine
(2) mepivicaine (3) bupivicaine |
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What is the duration of action of lidocaine?
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1-2 hours with moderate onset of 10-15 minutes
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How can lidocaine be prolonged?
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with a vascoconstrictor
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What is the duration of action of mepivicaine?
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1.5 - 3 hours
with RAPID onset 5 -10 minutes |
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Is there more or less vacodilation and swelling with mepivicaine?
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minimal vasodilaion and swelling
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How long does bupivicaine work?
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longer acting - 4 - 6 hours
-SLOW onset (15-20 minutes) |
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Is bupivicaine more or less potent than lidocaine?
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-4 times more potent BUT SAFETY margin less
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Why must you be careful with the use of bupivicaine and the calculation of doses?
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not as safe
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What are side effects to he use of locals on the CNS?
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muscle twitching
conclusions unconsciousness coma respiratory arrest -seen initially with toxic doses |
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What are side effects seen with the use of locals on the CV system?
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-peripheral vasodilation
-profound hyptension - direct myocardial depression -decreased ventricular contractility |
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During transduction, what converts the mechanical, chemical or thermal energy into electrical impulses?
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Free A-delta and C nerve endings or nociceptors
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Which fibers discharge at a high rate and are responsible for sharp qualities of First Pain?
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A - delta
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What percent of A-delta fibers are low threshold?
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75%
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Are most C fibers high or low threshold?
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high - therefore responsible for slow-onset or second pain
(burning and aching, initiates the self-preservation behaviors) |
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Which fibers are myelinated - A-delta or C?
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A-delta - therefore fast conduction
-FIRST PAIN -C fibers are unmyelinated and are solw therefore transmit poorly localized, dull pain |
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What is modulation?
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amplification or suppression of the peripheral sensory nerve impulses at the level of the spinal cord
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What is perception?
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integration, processing and recognition of sensory information
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What is alteration in the excitability of neurons in the brain and spinal cord caused by severe or chronic painful stimuli that activates A-delta and C nociceptors?
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central sensitization - hyperalgesia
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What are the 3 origins of pain?
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(1) somatic - bone, joints, muscle, skin (sharp and well-localized)
(2) visceral - not well localized, can be associated with nausea and vomiting (3) neuropathic - direct damage to peripheral nerves or spinal cord that is burning or shooting - hard to treat |
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What are some signs of pain?
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-loss of normal behavior
-expression of abnormal behavior -reaction to touch -physiologic - increase in HR, RR, BT, BP, dilated pupils |
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What are contrindications to NSAIDS?
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-renal or hepatic insuff
-GI problems -low circulating volume -coagulopathies -use of glucocorticoids or other NSAIDs |
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What drugs can be used for pain management?
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-opioids
-NSAIDS -alpha -2 (central opioid like effect) -locals - only lidocaine used IV -low dose of ketamine |
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What can a low dose of ketamine do?
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prevent and treat central sensitization and hyperalgesia - common in burns
-blocks glutamate action at NMDA receptor (NMDA antagonist) |
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How would you administer opioids if you want to keep plasma levels more consistent?
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opioid CRI
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How can buprenorphine be administered?
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Buccal transmucosal (dogs and cats)
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How can fentanyl be administered?
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transdermal - but with variable plasma levels
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What type of drugs can be injected IA?
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-local anesthetics
-opioids |
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What type of drugs would you want to use for epidurals?
-what are contraindications for the use of epidurals? |
preservative free
-sepsis and coagulopathies |
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What are side effects to epidural opiods?
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pruritis
urinary retention delayed respiratory depression -vomiting |
