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103 Cards in this Set
- Front
- Back
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what noninvasively measure arterial oxygen saturation and pulse rate continuously?
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Pulse oximetry
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what causes a left shift in oxyhemoglobin dissoc. curve?
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-alkalosis (decreased H+)
-hypothermia -decreased DPG -decreased CO2 |
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what causes a right shift in oxyhemoglobin dissoc curve?
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-acidosis (increased H+)
-hyperthermia -increased CO2 -increased DPG |
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pulse oximetry is based on what law?
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Beer-Lambert law of Spectrophotometry
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what is the Beer Lambert law?
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if a known intensity of light illuminates a chamber of known dimensions, the conc of the dissolved substances can be determined if the incident and transmitted light intensity are measured
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what wavelengths w/ greater absorbance w/ reduced Hb than w/ HbO2?
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660nm (red)
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what wavelength is the reference wavelength?
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940nm (infrared)
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what is the percentage of HbO2 and reduced Hb determined by?
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by measuring the ratio of infrared and red light transmitted to a photodetector
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what does pulse oximetry measure?
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functional saturation of Hb
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functional SaO2=?
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HbO2/(HbO2 + reduced Hb) x100
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what do laboratory co-oximeters measure?
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fractional SaO2
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fractional SaO2=?
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HbO2/(HbO2+reduced Hb+methemoglobin+carboxyhb)x100
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how many wavelengths of light are needed to differentiate and quantify 4 type of Hb?
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4 wavelengths of light
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the pulse ox is placed over a ________bed?
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arterial bed
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what are sites used for pulse oximetry?
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-finger
-ear -nose -toe -forehead children- palm and foot |
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what are some causes of reduced pulsatile blood flow to site that inhibits measurements of pulse ox?
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-hypothermia
-hypotension -altered vascular resistance -use of vasoconstrictive drugs |
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what are the limitations to Pulse oximetry?
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1-reduced pulsatile blood flow to site inhibits measurements
2-cardiopulmonary bypass results in signal loss 3-impedence of normal functioning |
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what are some things that can impede normal function of pulse ox?
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-motion
-electrocautery -ambient light -colored nail polish (blue, black,grn) -synthetic fingernails -IV dyes (Indigo carmine) -sig. presence of abnl hgb in blood |
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what will occur w/ SaO2 reading if have significant presence of abnl hgb in blood like methgb, cardoxyhgb, and sulfhgb)?
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renders false high SpO2 measurements
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what is accuracy of pulse ox when SpO2 is 70-100%?
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+/-2-3%
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what is accuracy of SpO2 when reads 50-70%?
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+/-3%
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what is response time of sat reading w/ a finger probe?
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24-35 seconds
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when would u use a pulse oximeter outside of the OR?
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-invasive line placement
-peripheral nerve blocks -PACU/ICU -transport of criticallyill pts -assess circulation after reconstruction and revascularization of extremeties and digits |
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what can cause an underestimation of SpO2?
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-low pulse pressure
-low perfusion -low CO -hypothermia -low Hb -increased SVR -motion artifact -electrocautery, ambient light, dyes -low PO2 <40mmHg |
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what can cause an overestimation of carboxyhgb?
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-absorbs 660nm light
-falsely high SpO2 when actual PaO2 is low -affinity to Hb 200% greater than O2 |
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w/ Methemoglobin what is SaO2 when reads >85%?
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falsely low
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w/ Methemoglobin (>10%) what is sat when read <85%?
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Falsely high
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what will cause no change in sat reading?
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-anema (Hct >10%)
-fetal Hgb -elevated bilirubin |
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what is capnography?
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produces a graphic record of instantaneous CO2 conc. of inspired and expired gases
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what are the uses of capnography?
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-continuously monitor CO2 production
-provides info about CO2 prod.,pulm perfusion, and resp patterns -early indicator of esophageal intubation and airway disconnection |
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ETco2=?
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PaCO2 as long as no V/Q mismatch
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what are some methods for measuring CO2 conc?
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-mass spectrography
-Raman spectrography -infared spectrography -photoacoustic spectrography |
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what is most common use of measuring ETcO2?
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mass spectrography-because it can measure conc of anesthetic gases
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what are the two types of CO2 sampling device?
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-sidestream capnometer
-mainstream capnometer |
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what type of Co2 device takes a gas sample from a T-piece at the ETT?
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sidestream capnometer
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where does the mainstream capnometer take a gas sample from?
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sensors inserted into the circuit for gas sample
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what is disadv. of mainstream capnometer?
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apparatus is very bulky
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what are adv of mainstream capnometer?
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-very short response times
-avoids the problems of clogged tubing, water traps, and sampling errors |
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what are the 4 phases of capnogram?
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1-inspiration
2-early point of exhalation 3-CO2 rich alveolar air (plateau) 4-fresh gas that is sampled during inspiration |
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when do you get the end-tidal CO2 from the waveform?
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at end of phase III.
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what are some causes of increased EtCO2?
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-hypoventilation-(most common)
-increased Co2 production -depressed resp center -inhibition of nerve impulses of resp muscles -blockade of NM junction -weakened resp muscles -COPD -obstructed airway |
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what are some causes of low EtCO2?
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-hyperventilation
-defect in sidestream analyzer -decreased CO2 production -decreased delivery of Co2 to lungs |
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what are some causes of decreased delivery of Co2 to lungs?
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PE, increased CO
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what can be a cause of decreased CO2 production?
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hypothermia
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what can cause a washout curve?
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-massive PE
-severe hyperventilation -profound hypothermia -severe hypotension -cardiac arrest |
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what can cause a rapid fall in EtCO2 to zero?
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-ventilator defect
-disconnect or kinked ETT -extubation |
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what can cause a rapid fall in CO2 to low but NOT zero level?
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low airway pressure indicates leak in system; high airway pressure indicated obstruction
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what can cause low CO2 w./ good alveolar plateau?
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-physiologic dead space ventilation
-possible miscalibration of unit, -wide PAO2-FiO2 gradient -good gas sample |
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what can cause a low CO2 w/o a good alveolar plateau?
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poor gas sample
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what can cause a slow decrease in CO2?
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-decrease systemic or pulmonary perfusion
-hypothermia -hyperventilation |
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what can cause slow increase in CO2?
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hypoventilation, hyperpyrexia
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what can cause sudden isolated increase in CO2?
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-sudden increase in CO or BP
-forced deep exhalation -release of tourniquet -sodium bicarb inj |
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what can cause sudden upward shift in base or topline?
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contamination of CO2 monitor
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what causes slow upward shift in base and topline of CO2 ?
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-miscalibration of unit
-contamination of unit -exhausted CO2 absorber -rebreathing |
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reasons for monitoring neuromuscular fxn?
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-determining degree of relaxation during surg. and degree of recovery before extubation
-facilitate timing of intubation -titrate dosage -monitor for development of phase II block -permit early recog. of pts w/ abnl plasma cholinesterase |
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what are the two nerves used to evaulate PNS?
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-ulnar nerve (adductor pollicis muscle)
-facial nerve (orbicularis occuli) |
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what are the types of PNS?
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-single twitch
-tetanus -TOF -DBS |
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assessing degree of blockade one visible twitch=?% blockade
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95% blockade
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assessing degree of blockade two visible twitch=?% blockade
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80-85% blockade
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assessing degree of blockade three visible twitch=?% blockade
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-75-80% blockade
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assessing degree of blockade four visible twitch=?% blockade
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<75%
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what does heat loss result from?
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-radiation (60%)
-conduction (3%) -convection (12%) -evaporation (25%) |
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heat loss is common during surgery because?
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-surgical environment transfer heat from the pt
-anesthesia reduces heat production -anesthesia diminishes the capability of pts to monitor and maintain thermoregulation |
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peri-op hypothermia predispose pts to what?
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-increase in metabolic rate (shivering) and cardiac work
-decrease in drug metabolism and cutaneous blood flow -impairments of coagulation -higher risk for development of post-op MI and wound infection |
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what are core temp sites reliable indicators of changes in mean temp?
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-bladder
-distal esophagus -ear canal -trachea -nasopharynx -rectum -pulm artery blood temp |
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what respond to temp changes by changing their electrical resistance?
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thermistors
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what are factors analyzed on the EEG tracing?
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-frequency
-amplitude -symmetry |
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what is an extremely important component of analyzing the EEG?
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-symmetry-focal increase or decrease in activity is usually indicative of pathology
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what is beta frequency?
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fast frequency typical of normal subjects who are awake and alert
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what is alpha frequency?
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(8-12 Hz)-typical in normal subjects who are relaxed with eyes closed
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what is delta 1 freq?
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(4-7Hz) seen during sleep
usually abnl if pt awake |
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what is delta 2 freq?
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(0-3Hz)
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T or F muscle relaxants have little effect on EEG?
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True
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hypoxia, hypotension, hypocarbia, hypoglycemia and ischemia cause what on EEG?
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slowing and flattening of the EEG
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what does hypercarbia cause to EEG?
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cause high-frequency EEG activity; at very high levels of CO2-flat EEG
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what are some cases where EEG monitoring is utilized?
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-carotid endarterectomy
-intracranial vascular surgery -cardiopulmonary bypass |
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what is most common use of intraop EEG monitoring?
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detection of ischemia
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what is produced by light stimulation of the eyes?
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visual evoked potentials
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how do auditory brainstem responses work?
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produced when sounds activates the cochlea following transmission through the external and middle ear
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when would ABR or BAER evoked potentials be used?
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-acoustic neuromas
-cerebellopontive angle tumors and post. fossa procedures |
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what is the least sensitive EP to anesthetic agents?
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ABR
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what is useful for monitoring fxn of sp cord or brain during spinal cord surg., endarterectomy, aortic surg. or repair of intracranial aneurysms?
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SSEP's
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when are motor evoked potentials used?
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evaluate descending motor pathways during neurosurg., orthopedic, or vascular procedures
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what is gold standard for evaluating motor potential?
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wake-up test
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what can be used as a measure of anesthetic depth?
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Bispectral index analysis (BIS)
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what are some indications for central line placement?
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-lack of peripheral veins
-inability to cannulate periphal veins -infusion of irritant substances -delivery of potent drugs -avoidance of medication interruptions -delivery of parental nutrition -CV access for monitoring or temporary transvenous cardiac pacing |
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what are some contraindications for central line placement?
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-distortion of landmarks for any reason
-suspected injury to SVC -morbid obesity -recently d/c'd subclavian catheter at same location -pneumothorax/hemothroax on contralateral side -carotid artery aneurysm precludes using internal jugular vein on the same side |
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if there is presence of significant coagulopathy what approaches are favored for central line placement?
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femoral or external jugular
(subclavian approach is least desired) |
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what are some complications of central line placement?
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-pneumothorax
-bleeding (hemothorax) -infection -arterial puncture -hematoma -venous thrombosis -air embolism -catheter malposition -pleural effusion -nerve injury -pericardial effusion -myocardial perforation/tamponade -cardiac dysrythmias |
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what is guideline for insertion lenght for internal jugular?
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right-12cm
left-14cm |
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what is guideline for insertion for subclavian?
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right-12-14cm
left-14-16cm |
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what is insertion length for femoral line?
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no limit
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what is level of PACU care determined by?
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1-degree of underlying illness
2-duration and complexity of anesthesia and surgery 3-risk of post-op complications |
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what are immediate care requirements on admission to PACU?
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-VS including HR,SBP,RR (q 5 min for 15 min)
-temp on admit -diagnostic tests only for specific indications |
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responsibility should never be turned over to PACU until what?
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pts airway status, ventilation, and hemodynamics are approp.
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what is a primary goal of PACU care?
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relief of surgical pain w/ minimal SE
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what is considered delayed emergence?
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failure to regain consciousness w/in 30-60min following a genral anesthetic
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what are some factors that can lead to delayed emergence?
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-hypothermia
-marked metabolic distirbances -peri-op stroke -obese pts -decreased protein binding -problems w/ excretion of meds |
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what are the objectives of post-op visits?
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1-gather information regarding response to anesthetic
2-provide information to pt 3-maintain rapport w. pt |
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what is safety zone 1 in MRI area?
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a public access area w/ no restrictions
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what is safety zone 2 in MRI area?
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semi-restricted area where pts and staff can interact
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what is safety zone 3 in MRI area?
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area is completely physically restricted from nonMRI personnel especially the general public
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what are goals of MRI sedation/anesthesia?
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-safety
-pt comfort -successful scan |
