Miscellaneous Anesthesia Notes (i.e. anesthesia machines, equipment, statistics, etc.) Flashcards
(251 cards)
0
Q
Name the types of anesthetic breathing systems (for all classifications)
A
- Open - insufflation - open drop - draw over
- Semi-open - Mapleson A, B, C - Mapleson D/Brain - Mapleson E - Mapleson F (Jackson-Reese)
- Semi-closed - Circle
- Closed - Circle
1
Q
How are anesthetic breathing systems classified?
A
- Open - Semi-open: No rebreathing but requires high flow fresh gas
- Semi-closed: most commonly used; associated with rebreathing of gases
- Closed: matches inflow gases to patient’s demand and associated with complete rebreathing
2
Q
What is the fibrillation threshold current?
A
100 mA
3
Q
What is the magnitude of a leakage current that is imperceptible to touch?
A
< 1 mA
4
Q
What is the maximum leakage allowed in OR equipment? (Why?)
A
10 microAmps
Because a current as low as 100 microAmps can be fatal if the high resistance offered by skin is bypassed and the microshock is applied directly to the heart.
5
Q
What are H & E cylinders? (What are the E-cylinder volume in respect to their pressures of the common gases & their corresponding colors?)
A
- H-cylinder: high-pressure cylinders, which most small hospitals store O2 in (connected by a manifold)
- E-cylinder: emergency cylinders located at the back of most anesthesia machines Gas
- O2: Pressure = 1800-2200 (2000) psi; Volume = 625-700 L; Color = green
- Air: Pressure = 1800-2200 (1800) psi; Volume = 625-700 L; Color = yellow
- N2O: Pressure = 745 psi; Volume = 1590 L; Color = blue
- CO2: Pressure = 838 psi; Volume = 1590 L; Color = gray
6
Q
What prevents incorrect attachment of the pipeline supply system to the anesthesia machine?
A
A non-interchangeable Diameter Index Safety (DIS) System
7
Q
What prevents incorrect E-cylinder attachment to the anesthesia machine?
A
The Pin Index Safety (PIS) System
8
Q
In the OR, how is a patient protected from electrical shock?
A
1) An isolation transformer isolates the OR power supply from grounds - the secondary wiring from the transformer is not grounded & provides 2 ungrounded voltage lines for OR equipment 2) Equipment casing (not the electrical circuits) is grounded through the longest blade of a 3-pronged plug (safety ground). - If live wire accidentally contacts a grounded patient, current will NOT flow through the patient
9
Q
What is a line isolation monitor?
A
- It reduces the chance of 2 co-existing faults by measuring the potential for current flow from the isolated power supply to the ground.
- [It determines the degree of isolation between the 2 power wires and the ground and predicts the amount of current that could flow if a 2nd short-circuit were to develop.]
- Alarm is activated if an unacceptably high current flow to the ground becomes possible (2-5 mA)
10
Q
How does pulse oximetry work? (What law is it based on?)
A
- It is based on an application of the Lambert-Beer Law - relates the concentration of a solute (hemoglobin) to the intensity of light transmitted through the solution
- Illuminates the tissue sample with 2 wavelengths of light
- 660 nm red light (isoberic point; 50% Hgb saturation); deoxyhemoglobin
- 940 nm infrared light (100% Hgb saturation; less red light absorption); oxyhemoglobin
- The amount of increased absorbance seen in the pulsatile component (in comparison to the nonpulsatile) is a measure of arterial oxygen saturation.
It is based on frequency sampling (the light acts like a strobe light; switching on and off 100s of times per second)
11
Q
What things can lead to measurement errors in the pulse oximeter? (3 components)
A
- Methemoglobin (MetHb) - it absorbs light almost equally in both red & infrared wavelengths - arterial saturation of 85% is usually seen (false reading)
- Carboxyhemoglobin - absorbs red light but NOT infrared light, therefore, arterial oxygen saturation values will vary widely
- Intravascular dyes (i.e. methylene blue)
- methylene blue can decrease O2 sat to ~65%
- other dyes (i.e. indigo carmine & indocyanine green) will cause spurious drops in measured saturation as well
12
Q
What does the spill valve on a machine do? (When is it open & when is it closed?)
A
- The spill valve vents excess gas to scavenging system
- It is closed during inspiration and the beginning of exhalation
- It only opens after full expansion of the bellows occurs and the pressure rise causes the spill valve to open
13
Q
What does the exhaust valve on a machine do?
A
It vents the driving gas of the bellows (which is typically oxygen)
14
Q
How are ventilators named? (Between ascending & descending ventilators, which is the safest & why?
A
Ventilators are named by the direction of the bellows during exhalation
- Ascending bellows are safer because descending bellows continue their normal movement despite ventilator disconnect
15
Q
What happens to the lungs if there is a hole in the bellows?
A
Alveolar hyperventilation & barotrauma can occur as the ventilator driving gas is forced into the circuit
16
Q
What is the content of soda lime? (What is the soda lime equation?)
A
- Soda lime is 94% Ca(OH)2; 5% NaOH; 1% KOH
- Equation is: CO2 + H2O = H2CO3 H2CO3 + 2 NaOH = Na2CO3 + 2 H2O + heat Na2CO3 + Ca(OH)2 = CaCO3 + 2 NaOH
17
Q
What does the size of the carbon dioxide canister have to do with rebreathing?
A
The size of the carbon dioxide canister MUST be greater than or equal to the patient’s tidal volume to prevent rebreathing irrespective of granule size.
18
Q
What factors influence the magnitude of carbon monoxide production from volatile anesthetics?
A
1) Dryness of the carbon dioxide absorbent
2) High temperatures of the absorbent, such as occurs during low flows
3) Prolonged high fresh gas flows, which cause dryness
4) The type of carbon dioxide absorbent with greater carbon monoxide production occurring on exposure to baralyme than soda lime
19
Q
What are the 4 basic types of circuit disconnect monitors? (Which will alarm first?)
A
1) Pressure alarms
2) Respiratory volume alarms
3) CO2 alarm or capnography
4) Others: SaO2 monitor, esophageal stethoscope, & TcO2
The low pressure monitor alarms if a critical airway pressure is not reached in the circuit. This is the first to alarm if a disconnect occurs.
Second alarm would be the mass spectrometer (capnogram)
20
Q
What does the O2 fail safe monitor detect do? (Datex-Ohmeda vs. North American Drager)
A
It detects a decrease in oxygen supply into the machine and shuts off the inflow of other gases until the O2 supply is re-established.
- Datex-Ohmeda uses a valve where if O2 pressure drops, flow of ALL other gases ceases
- North American Drager uses a valve where flow of all other gases decreases IN PROPORTION to the decrement of O2 flow (variable flow)
21
Q
What are the capacity, pressure, physical state, critical temperature, & US tank color for common gases on the anesthesia machine? (oxygen, nitrous oxide, CO2, & air)
A
- Oxygen: Capacity = 625 L; Pressure = 2200 psi; State = gas; critical temp = -120 Celsius; Tank color = green
- N2O: Capacity = 1590 L; Pressure = 745 psi; State = liquid; critical temp = 36 Celsius; Tank color = blue
- CO2: Capacity = 1590 L; Pressure = 845 psi; State = liquid; critical temp = 31 Celsius: Tank color = grey
- Air: Capacity = 625 L; Pressure = 1800 psi; State = gas; critical temp = -140 Celsius: Tank color yellow
22
Q
How do you figure out how much oxygen is left in an E-cylinder?
A
P1/V1 = P2/V2
22
Q
How to calculate how much time is left before the Oxygen tank is empty….
A
Current Gas Volume = Full Volume x [Current tank pressure/ Full tank pressure]
Where for oxygen:
- full volume = 700 mL
- full tank pressure = 2200 psi
- Then, Time Left = Current Gas Volume/ Flow Rate - If using the ventilator, you have LESS than the calculated time because some of the gas in the tank is being used to drive the bellows
- Different calculation when using N2O
23
How do you figure out how much nitrous oxide is left in an E-cylinder?
Because there is always an equilibrium between the gas & liquid state of N2O, you must weight the cylinder
When all of the liquid is vaporized, only then does the pressure begin to fall (~75% of the total is gone & ~215 L remains)
Some texts say 400 L remain after liquid is gone since 25% of 1600 = 400
* Once pressure does begin to fall, P1/V1 = P2/V2 - P1 = 750 psi and V1 = 215 L (or 400 L)
24
What is needed on an anesthesia machine to prevent delivery of a hypoxic mixture?
An O2 analyzer is needed in the inspiratory flow
25
Where should the Oxygen flowmeter be located and why?
* It should be placed downstream from ALL other flowmeters - to the far right in the U.S.
* This makes the deliver of hypoxic mixtures less likely to occur if a leak occurs; however it does NOT make it impossible
26
In a flowmeter at low flows, what does gas flow depend on?
Low flow are ***laminar*** and depend on the ***viscosity*** of the gas; present at the smaller diameter region of a thorpe tube (flow meter)
27
In a flowmeter, at high flows, what does gas flow depend on?
High flow is ***turbulent flow*** and depends on the ***density*** of the gas - This is present at the larger diameter region of thorpe tubes (flow meters) (A high Reynold's number is consistent with turbulent flow as a low Reynold's number is consistent with laminar flow)
28
How do barometric pressure changes effect flow through a flowmeter?
Barometric decreases (elevations above sea level) result in ***inaccuracies at high flows*** - ***density of gas decreases and delivered flow is greater than the flowmeter reports***
29
What is the best machine monitor to detect a flowmeter leak?
The Oxygen Analyzer
30
What are the advantages of IMV (intermittent mandatory ventilation) over Assist Control Ventilation? (How does it work vs. AC & SIMV?)
Advantages over AC:
* more comfortable for the patient and therefore less sedative required
* higher cardiac output due to lower intra-thoracic pressure
* less psychological dependence on the vent
IMV delivers a preset number of tidal breaths vs. AC which delivers a preset number of mechanical breaths and assists the patient's breathing effort. SIMV which synchronizes ventilation breaths with the patient's own ventilatory effort
31
What does the first-stage pressure regulator do?
It decreases the pressure from E-cylinder tanks
* oxygen at 2200 psi to 42 psi
* nitrous oxide from 745 psi to 26 psi
The North American Drager machine has a 1st stage pressure regulator but not a second stage pressure regulator
32
What does the second-stage pressure regulator do?
It decreases line pressure from the wall supply & the supply from the E-cylinders from ~ 50 psi to 14 psi
33
What is MAC?
MAC is the alveolar concentration at which 50% of patients will NOT respond to a surgical stimulus
It is a measure of anesthetic potency - Methoxyflurane is the most potent agent (also the least volatile)
34
What is the relationship of vapor pressure with volatile anesthetics? (What does it mean? And how does barometric pressure affect it?)
The percent of an anesthetic delivered increases with increasing vapor pressure - if a higher vapor pressure anesthetic is placed in a lower vapor pressure anesthetic vaporizer (i.e. isoflurane in sevoflurane vaporizer), then there will be a higher amount of gas delivered. Higher elevations means lower barometric pressure, therefore, the VP/BP ratio will increase - the delivered concentration is higher than indicated on the dial. - However, DO NOT adjust dial to lower concentration because the partial pressure is equal at sea level and the higher altitude: at sea level for Isoflurane - 2%(760) = 15.2 torr at higher altitude - 4% (380) = 15.2 torr
35
How does one detect a problem at the flowmeters on a machine?
Flowmeters are downstream from all safety devices except the Oxygen Analyzer - So one detection system is an FiO2 that does NOT match the flowmeter readings
36
How are flowmeters checked? (On a Drager machine vs. an Ohmeda machine)
- Drager machines - Positive pressure leak test - Does not detect micro flow leaks - Ohmeda machines - Negative pressure leak test
37
What is the composition of Baralyme?
- Baralyme's content: - 80% Ca(OH)2 - 20% Ba(OH)2 - Baralyme's breakdown: Ba(OH)2 + 8 H2O + CO2 = BaCO3 + 9 H2O + heat 9 H2O + 9 CO2 = 9 H2CO3 9 H2CO3 + 9 Ca(OH)2 = 9 CaCO3 + 18 H2O + heat
38
In an arterial waveform, what does an underdamped system cause? (What situation leads to an underdamped system?)
- An underdamped system leads to falsely high systolic and falsely low diastolic pressure measurements - Can be caused by: - very short or long tubing ( \> 1.5 m long) - stiff tubing (poor, low compliance) - big catheter (\<18 gauge in radial artery)
39
In an arterial waveform, what situation can cause an overdamped system?
Caused by: - high viscosity of solution - low density of solution - soft, high compliance tubing - bubbles in the system - small tube diameter (\< 1.5 mm) - long tube length
40
How does the oscillometric manual BP device work?
- The cuff is inflated above SBP (no oscillations) - As the cuff deflates, an abrupt increase in the magnitude of oscillations is the SBP - oscillation magnitude increases to a peak then falls rapidly. The point in which there is no longer an alteration in the magnitude of oscillations is the DBP - Many machines calculate the MAP using various formulas examining the rate of change of pulsation
41
CVP / PCWP Waves
* Pneumonic: **A**ll **C**ollege e**X**ams **V**ary **Y**early -
* **A wave**: atrial contraction - just before 1st heart sound and carotid pulse - lost with Afib - large waves indicate contraction against the tricuspid valve as seen in heart block, nodal rhythms, or tricuspid stenosis, pulmonary HTN (after p wave on ECG)
* **C wave**: onset of ventricular systole (ventricular contraction) - tricuspid valve closure (after QRS on ECG)
* **X descent**: (opening of pulmonic/aortic valve) starts with atrial relaxation - continues as RV, contracting during systole, pulls floor of RA down (during T wave on ECG)
* **V wave**: filling of RA during systole (venous return) - large waves are the result of tricuspid regurgitation (after T wave on ECG)
* **Y descent**: tricuspid/mitral valve opens early in diastole (before p wave on ECG)
42
What does the pumping effect in vaporizers refer to?
- It refers to the increase in anesthetic concentration from a vaporizer when there is reversed gas flow through the vaporizer as may occur during assisted or controlled ventilation - The effect is more pronounced at low flow rates
43
What is the indicator in carbon dioxide absorbent?
Ethyl violet
44
What does capnography rely upon? (and what is it a function of?)
- Capnography relies upon infrared absorption and represents an evaluation of the carbon dioxide waveform - Infrared absorption is a function of molecular weight
45
How does mass spectometry work?
- It works by analysis of the molecular mass to the charge - After being ionized by a beam of electrons, a gas molecule is accelerated by an electric field and then shot into a magnetic field where the radius of curvature depends upon the mass of the molecule.
46
What are the 3 major indirect & the 3 direct monitors of respiration?
- Indirect monitors 1) impedence pneumography: electrodes on thoracic cavity with low intensity alternating current 2) pressure sensitive pads 3) pneumatic abdominal sensor - Direct monitors 1) thermisters: placed in front of the mouth or nose 2) proximal airway pressure sensors: also located at the mouth or nose with pressure sensitive switches 3) infrared carbon dioxide sensors
47
How does pulse oximetry work?
- Transillumination of tissue with 2 frequencies of light: - 940 nm, which corresponds to 100% saturation of Hgb (and the absorption of red light) OXYHEMOGLOBIN - 660 nm, which corresponds to 50% Hgb saturation (also called the isobestic point & corresponds to the absorption of more red light) DEOXYHEMOGLOBIN - Measures a difference between background absorption during diastole and peak absorption during systole. A ratio. - Frequency sampling
48
How does carboxyhemoglobin effect pulse oximetry?
CarboxyHgb is viewed by the pulse oximetry as oxygenated Hgb - results in an overestimation of oxygenation A co-oximeter must be used to distinguish the two
49
How does methemoglobin (MetHb) effect pulse oximetry?
MetHgb is seen by the pulse oximeter as having a saturation of ~85%
50
What is Transcutaneous Oxygen Monitoring (TCOM)? (What concept is it based on? How does it work? What are its limitations?)
- TCOM is a noninvasive way to measure oxygenation - It is based on the concept of - capillary PO2 may approximate arterial PO2 in areas of the skin where local blood flow exceeds the amount necessary for local tissue oxygen needs (especially in warmed areas). Generally, PtcO2 is ~80% of actual arterial oxygen tension. - Electrode is attached to the skin, which is warmed to 40-45 Celsius (vasodilation). Oxygen then diffuses through the skin into a Clark type electrode for direct measurement. - Limitations: - erroneous measurements in the presence of peripheral vasoconstriction; decreased cardiac output; thick skin - skin burns result from prolonged application - sudden decreases in PaO2 are not detected because of the slow diffusion time of oxygen across the skin
51
How does systolic pressure differ in the aorta vs. the radial artery?
- Systolic pressure in the aorta is far lower than in the radial artery - The further into the periphery one progresses, the greater the systolic pressure and the lower the diastolic pressure (increase in the pulse pressure) (Note: radial artery has a wider pulse pressure than the aortic pressure)
52
In what situations are PA catheters useful? (why is it useful in those situations?)
- PA catheters are useful in major surgery with major fluid shifts in the presence of: - severe LV dysfunction or cardiac failure - pulmonary hypertension - cor pulmonale - It is useful in its ability to monitor both preload and afterload to reduce myocardial oxygen consumption - Can calculate: - cardiac output - mixed venous gas sampling - systemic vascular resistance
53
What are "a" and "v" waves indicative of on a PA tracing?
* Large "a" waves - mitral stenosis - complete heart block - atrial myxoma - early acute heart failure
* Giant "v" waves may or may not be seen with mitral regurgitation (but may not correlate with the magnitude of MR)
* Large "v" waves: - mitral stenosis - congestive heart failure - ventricular septal defect
54
What are contraindications to PA catheterization?
- Mechanical heart valves (absolute) - Relative contraindications: - recently inserted transvenous pacemaker - bifasicular heart block or complete LBBB - coagulopathy - frequent dysrhythmias - WPW Syndrome - h/o pulmonary stenosis - Ebstein's malformation (a congenital heart defect where the septal leaflet of the tricuspid valve is displaced towards the apex of the right ventricle
55
In what settings is thermodilution cardiac output immeasurable or inaccurate?
Pneumonic TIA - Tricuspid regurgitation - Intracardiac shunts - atrial fibrillation
56
What situation(s) will cause thermodilution cardiac output (CO) to be artificially elevated?
- Anything that would cause a decreased amount of injectate - smaller volume injected - An increase of 1 degree Celsius causes an artifactual 3% increase in CO (computer believes the temperature increases is due to increased mixing) - Intracardiac shunts (increased mixing) - Slow indicator injection time leads to increased mixing
57
What situation(s) will cause thermodilution cardiac output (CO to be artificially lower?
- Increased volume of injectate - Cold blood - Decreased cardiac output (CO)
58
EEG frequencies
- Delta (0-4 Hz): deep sleep, deep anesthesia, hypoxia, tumors, high dose opiates - Theta (4-8 Hz): sleep, anesthesia, hyperventilation, moderate dose opiates - Alpha (8-13 Hz): resting, alert adult; dominant frequency in the awake state - Beta (13-30 Hz): mental concentration, barbiturates, benzodiazepines
59
Causes for increased EEG frequency
Hypoxia: initial Hypercarbia: mild Seizure Barbiturates: small dose Diazepam N2O: 30-70% Inhalation agents \< 1 MAC Ketamine
60
Causes for decreased frequency, increased amplitude on EEG
Hypoxia: mild Hypocarbia: moderate to extreme Hypothermia Barbiturates: moderate dose Etomidate Narcotics Inhalation agent \> 1 MAC
61
Causes of decreased frequency, decreased amplitude on EEG
Hypoxia: marked Hypercarbia: severe Hypothermia Hypotension Barbiturates: large dose
62
Causes for electrical silence on EEG
Brain death Hypoxia: severe Hypothermia: profound Barbiturates: coma dose Isoflurane: 2 MAC Halothane: 4 MAC
63
In a closed (circle) circuit system, how much fresh gas inflow satisfies the body's metabolic oxygen requirements?
150-500 mL/min
64
What are the advantages/disadvantages of a closed (circle) system?
- Advantages - maximal conservation of heat and humidity - economical to use and associated with low pollution - partial rebreathing of CO2 is permitted and exhaled CO2 is neutralized in the CO2 absorber - Disadvantages - anesthetic concentration cannot be rapidly changed
65
What factors affect transthoracic resistance (TTR) to DC fibrillation?
- Pressure on the chest: by decreasing chest wall diameter & increasing paddle contact with the chest - Size of paddles: larger paddles can decrease TTR, increase current flow, & improve likelihood of successful defibrillation - Salt-containing coupling agent: decreases TTR (vs. non-salt containing agent) - Phase of ventilation: chest wall resistance is lower at end expiration - Consecutive serial shocks: reduces TTR - Hypoxia: reduces likelihood of successful defibrillation - Acidosis: reduces likelihood of successful defibrillation
66
What are the components of calcium hydroxide, soda lime & baralyme carbon dioxide absorbents?
- Calcium Hydroxide - Ca(OH)2, CaCl2 - calcium sulfate & polyvinylpyrrolidine, which enhance hardness and porosity - does not produce carbon monoxide & compound A - Soda lime - 95% Ca(OH)2, 5% NaOH, 1% KOH - Silica (to decrease dust formation) - Baralyme (produces more CO than soda lime) - predominantly barium hydroxide & Ca(OH)2 equally - no silica: baralyme is inherently harder and silica is not required with it to induce hardness [Ca(OH)2 is the common component of them all, which is the least reactive base]
67
What is the half life of blood stored? (citrate-phosphate-adenine anticoagulant preservative (CPD-A) vs. acid-citrate dextrose (ACD) stored blood)
35 days for CPD-A vs. 21 days for ACD
68
What situations may result in a PCWP value that is artifactually greater than LVEDP?
- Mitral stenosis - Atrial myxoma (left): ball-valve effect preventing proper emptying of the right atrium - PEEP: increased airway pressure
69
What situations may result in a PCWP value that is artifactually less than LVEDP?
- LV is very noncompliant - LVEDP is greater than 25 mmHg - Aortic insufficiency leads to premature closure of the mitral valve
70
How does retinal artery thrombosis typically occur?
It is usually caused by pressure on the eyes.
71
How is a pulmonary artery rupture treated?
- The nonbleeding lung must be protected by the insertion of a double lumen endotracheal tube. - volume resuscitation - surgical exploration & lung resection may be required
72
Hypoxia secondary to failure of the oxygen supply may be due to....
- a cracked flowmeter - transposition of pipes during construction - failure of the reducing valve - an accidental change of flowmeter setting - A shift of the oxyhemoglobin dissociation curve does not affect the oxygen supply
73
What is the most common cause of anesthetic disasters?
Hypoxemia, which is the endpoint of other problems (e.g. esophageal intubation, hypotension, and machine problems).
74
The highest incidence of intraoperative awareness occurs during which type of surgery?
Trauma surgery - the incidence of intraoperative awareness in trauma is estimated to be between 11 and 43%. - the incidence of awareness in nonobstetric or noncardiac cases is estimated to be ~ 0.2%
75
What is the statistical term for the spread of individual values in data with a normal distribution?
The standard deviation
76
What is the statistical term for the difference of each value from the mean?
The variance
77
Define the standard error of the mean?
It is a precision factor
78
How long should patients who undergo outpatient surgery with Isoflurane abstain from driving or operating machinery?
Patients should not drive or operate machinery for AT LEAST 16 hours post-op. - there is some data suggesting that 2 days may be more appropriate
79
What is the motto on the seal of the American Society of Anesthesiologists (ASA)?
Vigilance
80
What is the first step that an anesthesiologist must do once a airway fire occurs? (What are the subsequent steps?)
1) Stop ventilation/ disconnect the the circuit to stop the supply of oxygen-enriched gas 2) Surgeon should flood the field; extinguish the fire 3) Once the fire is extinguished, ventilate patient with 100% O2 4) Perform a direct laryngoscopy followed by a bronchoscopy, to examine the airway
81
What is the most common anesthesia-related reason for admission to the hospital following an outpatient surgical procedure?
Nausea/vomiting
82
Where is the doctrine of res ipsa loquitur applicable?
The doctrine of res ipsa loquitur (the thing speaks for itself) is invoked if the accident usually does not happen without negligence, the plaintiff was not a factor, and the defendant usually has control of whatever caused the accident. - Settling out of court is not a factor
83
What are OR personnel at increase risk of obtaining due to exposure?
- The incidence of spontaneous abortions - The number of congenital abnormalities in the children of exposed males and females - Liver disease (more often in male anesthesiologists)
84
What is the incidence of hepatitis after blood transfusion? (Hepatitis B vs. C)
- The risk of hepatitis C via blood transfusion is approximately 1 case per 200,000 units transfused - The incidence of hepatitis C is 3 times more likely than hepatitis B - The incidence is lower if the donor pool is volunteers - Transfusion of red cells does NOT carry a higher risk
85
What does the mark "Z-79" on an endotracheal tube indicate?
It refers to a committee of the American National Standards Institute which identifies the tube as nontoxic and in compliance with the standards set down. - the initials "I.T." = implant tested and show that the tube is nontoxic
86
What factors lead to an increased risk of the development of gram negative rod pneumonia in mechanically ventilated patients?
- excess moisture in the ventilator - increased FiO2, which decreases mucociliary function - frequent tracheal suctioning decreases host defenses - H2 receptor antagonists increase gastric pH, making bacterial colonization of stomach more likely; since aspiration is a common risk in ventilated patients, this can become an additional source of bacteria
87
How does Intermittent Mandatory Ventilation (IMV) work?
- it allows the patient to maintain his or her own breathing and receive a prescribed number of breaths per minute from the ventilator - it differs from assisted ventilation in that the breaths from the ventilator do not augment the patient's breaths
88
What are supportive therapies recommended for early ARDS?
- Low tidal volume ventilation - PEEP to recruit atelectatic portions of the lung, thereby diminishing shear forces associated with repeated opening and closing of lung units; also reduces shunting - NO role for prophylactic antibiotics
89
What therapies diminish mortality rate in severe sepsis?
- activated protein C, an anti-inflammatory and anticoagulant medication - early fluid and vasopressor use directed to physiologic goals - a combination of corticosteroid and mineralocorticosteroid treatment in patients with adrenal insufficiency - tight glucose control with use of insulin infusion
90
Increased levels of what hormones/chemicals contribute to hyperglycemia in sepsis?
- Elevations in circulating levels of EPINEPHRINE, CORTISOL, AND GLUCAGON
91
What conditions yield a respiratory quotient ratio \> 1 or \< 0.7?
A normal R/Q is ~ 0.8 - Metabolism of carbohydrates yields an R/Q of 1 - Metabolism of the more efficient fats yields an R/Q closer to 0.7 - an R/Q \>1 in a critically ill patient indicates excessive caloric intake with lipogenesis and may impair weaning from the ventilator
92
What is the normal difference between the end tidal CO2 reading and the actual PaCO2?
The number is normally 2-5 mmHg less than the PaCO2; this gradient reflect alveolar dead space.
93
What is the Fick Principle?
It states: The amount of oxygen consumed by an individual (VO2) is equal to the difference between arterial and venous (A/V) oxygen content multiplied by the cardiac output (CO) CO = VO2 / CaO2 - CvO2 [note: CaO2 = 0.0138 x Hgb x SaO2) + (0.003 x PaO2)]
94
What is monitored by Somatosensory Evoked Potentials (SSEPs)?
- dorsal root ganglia - posterior columns - brainstem - medial meniscus - internal capsule - contralateral somatosensory cortex
95
What 2 things are not monitored with SSEPs?
- Lateral spinothalamic tract - anterior horn cells
96
What factors increase latency and decrease amplitude of SSEPs?
- injury/ cord compromise - hypoxemia - hypercarbia - hypotension - hypo/hyperthermia - volatile anesthetics, N2O, diazepam, high dose pentothal
97
When does the fail-safe device alarm?
When oxygen pressure falls below 30 psi. The failsafe device is located downstream from nitrous oxide supply source in order to shut off or proportionately limit the supply of nitrous oxide if oxygen pressure decreases
98
What breathing circuit is best for spontaneous ventilation? Which one is 2nd, 3rd, and 4th best?
Mapleson A breathing circuit is best for spontaneous ventilation. A Dog Can Bite or All Do Continue Breathing Mapleson A \> D \> C \> B
99
Which breathing circuit is best for controlled ventilation? Which is 2nd, 3rd, and 4th best?
The Mapleson D breathing circuit (i.e. Bain circuit) is best for controlled ventilation. Dog Bites Can Ache or Dead Babies Can't Assist Mapleson D \> B \> C \> A
100
What are the advantages of using a circle system breathing circuit?
- stability of inspired concentrations - preservation of respiratory moisture/heat - prevention of operating room pollution - allows use of closed circuit anesthesia or with low-flow oxygen
101
What are the disadvantages of the circle system breathing circuit?
- Having 10 connections allows for multiple potential sites for: disconnections, obstructions from valves/debris, and/or leaks.
102
What are the 5 criteria assessed for ambulatory discharge of a patient?
- vital signs - ambulation and mental status - pain and PONV - surgical bleeding - fluid intake/output (although patients' ability to drink and void is no longer mandatory for discharge)
103
What must all ambulatory surgical patients have before discharge?
- an escort home - postoperative instructions with a contact for post-operative problems
104
What blood test can be taken to confirm the diagnosis of an anaphylactic reaction?
- Typtase levels: tryptase is a protein released during anaphylaxis - antibody levels: antibodies produced in response to certain allergens - histamine levels
105
What is considered "deep sedation"?
Unconciousness; an induced state of sedation characterized by depressed conciousness such that the patient is unable to continuously and independently maintain a patent airway and experiences a partial loss of airway reflexes and ability to respond to verbal commands or physical stimulation.
106
What effects does morbid obesity have on the respiratory system?
- Restrictive lung disease (overall) with a vital capacity
107
What occurs to the cardiac system in morbidly obese patients?
- Increased CO leading to hypertension and LVH - Cor pulmonale occurs secondary to hypoxia induced increase in pulmonary vascular resistance and pulmonary HTN
108
What is the term for the inhaled concentration associated with response to verbal stimulation?
MAC-awake
109
What is the term for the inhalation concentration associated with the response to movement to incision?
MAC
110
What is the term used to describe the inhaled concentration associated with the hemodynamic response to incision?
MAC-BAR
111
What does standard deviation (SD) describe?
SD is used to describe the spread of data
112
What is the standard error of the mean (SEM) useful for? And how does it differ from the standard deviation (SD)?
It is the means which are computed from multiple grouped determinations of the data set. SEM is used to compare data sets; as more data is gathered, the smaller the SEM will become. The difference between SD and SEM is that SD is used to describe the data, and SEM is used for computations about the certainty of the mean of the data. SEM is always smaller than SD.
113
What statistical test is best for comparing 2 groups?
Unpaired t-test (e.g. one group gets a drug, the other gets standard treatment) - has less power than the paired t-Test due to increased variability between the 2 groups - for ordinal data, the Mann-Whitney U test is equivalent
114
What statistical test is best for comparing a group with value?
t-Test which is used for parametric data
115
What statistical test is best for comparing 3 or more groups?
Analysis of Variance (ANOVA)
116
What statistical test is best for comparing 2 paired groups?
Paired t-test (e.g. pre/post testing; before/after some event)
117
What statistical test is best for comparing multiple matched groups?
Repeated measures ANOVA
118
Describe the 4 patterns of electrical stimulation (with suprmaximal square-wave pulses)
- Tetany: a sustained stimulus of 50-100 Hz, usually lasting 5 seconds - Twitch: a single pulse 0.2 ms in duration - Train of four (TOF): a series of four twitches (every 0.5 sec) in 2 seconds (2-Hz frequency), each 0.2 ms long - Double-burst stimulation (DBS): 3 short (0.2 ms) high-frequency stimulations separated by a 20 ms interval (50 Hz) and followed by 750 ms later by 2 or 3 additional impulses
119
Of the four patterns of electrical stimulation, which 2 are the preferred methods for determining adequacy of recovery from a nondepolarizing block?
1) sustained tetany 2) double burst stimulation (fade is more obvious with the above 2 methods in comparison with TOF or repeated twitches)
120
What is a line isolation monitor?
The line isolation monitor detects when a faulty ground connection is one step away from establishing a large current in the patient. - it sounds an alarm when the current that could flow to ground exceeds 5 mA
121
Define mode
The most frequently used number of a group of numbers.
122
What is the percentage number associated with Mean +/- 1 Standard Deviation (SD)? Mean +/- 2 SD? Mean +/- 3 SD?
Mean +/- 1 SD = 68% Mean +/- 2 SD = 95% Mean +/- 3 SD = 99%
123
What is the p value?
It is a summary of the statistical strength of the data analysis in supporting or rejecting the null hypothesis, which states there is NO difference between 2 groups of data.
the probablity of obtaining a data set if in reality the null hypothesis were true
124
What is a Type 2 (beta) error?
It is the probability of falsely ACCEPTING the null hypothesis (saying there is NO difference when, in fact, there IS a difference)
125
What is a Type 1 (alpha) error?
It is the probability of falsely REJECTING the null hypothesis (saying there IS a difference when there is NO difference) P-value can also be viewed as the probability of a type 1 error
126
What is a cohort study used to determine?
Is a study to observe a long period of time in a prospective manner.
127
Who was the first person to hold an academic position in anesthesiology at an American university?
Ralph M. Waters at the University of Wisconsin in 1927
128
What is the Ideal Gas Law Equation?
V = nRT/P n = moles [which can be calculated by dividing the specific gravity (grams) by the molecular weight (grams/mol)] R = ideal gas constant = 0.082 (L\*atm)/ (K\*mol) T = temperature converted to K (add 273 to degrees Celsius) P = atmospheric pressure
129
What is the minimum amount of volatile anesthetic necessary to prevent movement in response to intubation?
When used alone, the concentration of volatile anesthetics needs to be 1.5 times MAC
130
How is the time constant of an anesthesia circuit calculated?
The time constant of a circuit is its total volume divided by the fresh gas flow rate.
131
How does gas flow effect the lifetime of a canister of soda lime?
The higher the gas flow, the longer the soda lime will last.
132
What is the one parameter that must be met in a closed-circuit anesthesia machine?
Oxygen consumpsion - in any anesthesia system, the one factor that MUST be provided for is oxygen. - in a closed-circuit system, the inflow of fresh gas matches that which is taken up by the patient
133
What is the protocol for when a vaporizer tips over?
The vaporizer must be righted and flushed with fresh gas at high flow rates for at least 30 minutes with the vaporizer set for a low concentration of agent
134
What is the use of a negative-pressure leak test?
It is a universal test for leaks in the low-pressure circuit of anesthesia machines, regardless of whether the low-pressure circuit contains a check valve. - performed by placing a suction bulb to the common gas outlet (from which the carbon dioxide absorber has been disconnected) with the machine's master switch turned OFF.
135
What is the pumping effect in reference to a vaporizer? When is the effect most pronounced?
It refers to the increase in anesthetic concentration from a vaporizer when there is reversed gas flow through the vaporizer as may occur during assisted or controlled ventilation. - The effect is more pronounced at low flow rates
136
What is the difference between the electric current supplied by electrocautery machines vs. that by wall electrical outlets?
Electrocautery machines use ALTERNATING CURRENT of a much HIGHER FREQUENCY (~ 10^5 to 10^6 Hz) Wall electrical outlets supply ALTERNATING CURRENT at a frequency of 60 Hz (in the US; 50 Hz in some other countries)
137
What should the bladder length and width of a noninvasive blood pressure cuff be for accurate measurement?
The bladder length should be at least 80% and the width 40% of the limb circumference
138
What is the equation for Ohm's law?
Current (in amps) = Voltage (in volts) / Resistance (in ohms)
139
How does the Vapor 19.1 vaporizer maintain temperature compensation?
By virtue of an expansion element that extends into the vaporizing chamber. - no heating elements are involved
140
What are the standard measurements for anesthesia breathing circuit and ventilator fittings?
- 15 mm for endotracheal tube fitting - 22 mm for the breathing system fitting ( the fitting for the scavenger hose is 19 mm)
141
How are oxygen and nitrogen measured on an anesthesia machine?
By mass spectroscopy or Raman spectroscopy. - oxygen may also be measured by electrochemical or galvanic detectors
142
How are volatile anesthetics and nitrous oxide measured on an anesthesia machine?
Via infrared spectrometry
143
What happens to end tidal CO2 and expired nitrogen with the occurrence of a venous air embolism?
* etCO2 will decrease on capnometer
* expired nitrogen will increase by mass spectroscopy
144
What ECG signal is recorded & where is the correct placement for leads, I, II, V1, and V6?
* Lead I: displays ECG signal recorded from the left arm and the right arm
* Lead II: displays the ECG signal recorded from the right arm and the left leg
* Lead V1: is placed just to the right of the sternum in the 4th intercostal space
* Lead V6: displays the ECG signal recorded from a unipolar electrode placed in the 5th intercostal space at the left midaxillary line
145
What differentiates Datex-Ohmeda anesthesia machines' high pressure system from North American Drager machines?
Datex-Ohmeda anesthesia machines are the only ones that have a 2nd stage pressure regulator that reduces in line working pressure from 45 psi to 15-25 psi
146
What should you do if pipeline gas failure or crossover occurs in the anesthesia machine?
1. Turn on the cylinder source
2. Disconnect wall source because the machine preferentially uses 50 psi wall source instead of 45 psi regulated cylinder supply
147
What are the differences between Datex-Ohmeda anesthesia machines and North American Drager machines?
1. Datex-Ohmeda (DO) machines have a 2nd STAGE O2 PRESSURE REGULATOR and North American Drager (NAD) machines do noted reducing line pressure from 45-50 psi to 15-25 psi
2. The O2 FAIL-SAFE VALVE SYSTEM on the DO machines is ALL OR NOTHING where ALL other gases cease if there is an O2 pressure drop. With NAD machines there is a VARIABLE FLOW response where all other gases decrease IN PROPORTION to the decrease in O2.
3. DO are the only machines with an UPSTREAM ONE-WAY CHECK VALVE that ensures ALL 50 psi of O2 will enter the fresh gas flow (which prevents the ability to perform a positive pressure leak test past the flowmeters).
4. For VENTILATOR DRIVE, DO machines use 100% OXYGEN, whereas NAD machines use a air/O2 mixture
5. DO uses CHAIN-LINKED SPROCKETS to control ratio of O2 TO N2O (never exceeds 3:1 ratio). NAD uses a PNEUMATIC INTERLOCK SYSTEM to limit N2O flow to achieve the same ratio (can still deliver hypoxic mixture)
148
What are 5 ways that the anesthesia machine can deliver a hypoxic mixture of gas?
1. Wrong supply gas attached
2. Defective mechanics
3. Downstream leaks (the multigas and O2 analyzers are the only things that detect this problem)
4. Inert gases (heliox and CO2 are not linked to O2 flow)
5. Dilution of FiO2 by less potent volatile anesthetics (desflurane)
149
How would Heliox affect oxygenation in a patient with tracheal stenosis with poor oxygenation?
It will improve oxygenation during conditions of TURBULENT flow only (due to its lower density)
150
How do very low fresh-gas-flow rates effect vaporizer output of inhaled anesthetics? How do very high fresh-gas-flow rates effect it?
* For very low fresh-gas-flow rates: Output will DECREASE due to INSUFFICIENT TURBULENCE in the vapor chamber to upwardly advance vapor molecules.
* For very high fresh-gas-flow rates: Output will still DECREASE due to INCOMPLETE MIXING in the vapor chamber because of the rapid flow.
151
How does the use of N2O in fresh gas flow affect vaporizer output?
Due to the solubility and viscosity, N2O, in general DECREASES vapor output
152
For Desflurane, what happens to the concentration at high altitudes? What should be done to compensate?
Unlike other volatile anesthetics whose partial pressure does not change, Desflurane vapor chamber is CLOSED TO THE ATMOSPHERE, therefore: - the amount of Desflurane vapor STAYS CONSTANT - partial pressure changes: at sea level - 6% (760) = 45.6 torr at high altitude - 6% (380) = 22.8 torr - Therefore, you would need to increase the concentration dial
153
How is CO2 detected in the operating room by the anesthesia machine?
Infrared Absorption Spectrophotometry (IRAS)
154
What is Raman Scattering used for? How does it work?
It used for measuring O2, N2, N2O, CO2, H2O vapors and inhaled anesthetic agents It is the result of photons generated by a high-intensity argon laser colliding with gas molecules. These photons are measured as peaks in a spectrum that determine the concentration of respiratory gases and inhaled vapors
155
What synthetic dye causes the greatest spurious decline in oxygen saturation?
Methylene Blue
156
By what methods is Oxygen measured? Describe each.
1) Paramagnetic Analysis: these analyzers detect the change in sample line PRESSURE resulting from the attraction of O2 by switched magnetic fields. Signal changes during this electromagnetic switching correlate with the O2 concentration 2) Polarographic Analysis: an electrochemical system where the CURRENT change is proportional to the number of oxygen molecules surrounding the electrode [these type of O2 sensors are important components of gas machine O2 analyzers, blood gas analyzers, and transcutaneous O2 analyzers] (ACID-BASE LIKE REACTION: O2 + 2H2O +4e- --\> 4OH-) 3) Galvanic Cell Analysis: measure the CURRENT produced when O2 diffuses across a membrane and is reduced to molecular O2 at the anode of an electrical circuit; the current is proportional to the partial pressure of O2 in the fuel cell. LIKE A BATTERY (In the anesthesia machine)
157
What is post-tetanic count (PTC) Stimulation good for determining?
It is useful during intense blockade, where there is NO response to tetanic stimulation or TOF. It allows one to determine the time until return of the first response to TOF stimulation based on the number of post-tetanic twitch responses present at a given time
158
What is the percent sensitivity of detecting myocardial ischemia with continuous monitoring of leads II and V5?
80%
159
What does the loss of A wave on the CVP waveform indicate? What does a cannon A wave indicate?
* Loss of A wave is indicative of atrial fibrillation
* Cannon A waves are indicative of either A-V dissociation or Tricuspid stenosis (which is also represented by a small Y descent)
160
What does a tall C and V wave with No X descent on a CVP waveform indicate?
Tricuspid Regurgitation
161
What does a combination of tall A and V waves with an M or W configuration on the CVP waveform indicate?
**RV ischemia or Pericarditis** (the peak in the V wave is classically associated with this)
162
What is Laplace's Law and equation?
**T = (Pr)/ 2L**
## Footnote
where T = tension, P = pressure, r = radius, L = wall thickness
Can be applied to the LV, alveolus, and aorta
Example: The thinner the myocardium (wall thickness) the greater the afterload (tension)
163
What 3 components are directly proportional to afterload?
1) LV end-diastolic pressure 2) LV circumferential wall tension 3) LV radius (LV wall thickness is INVERSELY proportional)
164
What is the Oxygen content (CaO2) equation?
CaO2 = Hgb(1.34)(SaO2) + PaO2(0.003)
165
How is Coronary Perfusion Pressure (CPP) calculated?
CPP = AoDBP - LVEDP
166
Compared to central venous catheters, peripherally inserted arterial catheters have what rate of bacterial colonization? (greater, lower, or equal)
Equal rate of bacterial COLONIZATION (not infection rate)
167
What is the current estimation of the incidence of central line associated bloodstream infection?
5%
168
Which mechanism of heat transfer MOST accounts for heat loss perioperatively?
Radiation - loss of heat through photons (like a warming lamp for babies)
169
Isoelectric EEG is obtained using high dose thiopental. What is the maximum achievable reduction in CMRO2?
50% Only way to reduce it any further is by hypothermia
170
During synchronized cardioversion which of the following requires the least amount of energy for the initial shock? a) atrial fibrillation (biphasic shock) b) atrial flutter (monophasic shock) c) PSVT (biphasic shock) d) PSVT (monophasic shock)
Atrial flutter (monophasic shock)
171
What is the Henderson-Hasselbalch equation?
pH = pK + log [HCO3-] / 0.03 x PCO2
172
What is the equation to estimate dead space? What principle does it represent?
VD/VT = (PaCO2 - PECO2) / PaCO2 PECO2 = mixed-expired CO2 VD = dead space ventilation VT = tidal ventilation Represents the Bohr Effect which states that in the presence of CO2, the O2 affinity for dissociation decreases, therefore, an increase in CO2 or decrease in pH (acidic) leads to decreased O2:Hgb affinity (a right shift on the oxy-Hgb dissociation curve)
173
What is the alveolar gas equation?
PAO2 = FiO2 (Patm - PH2O) - [PaO2/RQ] RQ = 0.8 Patm = 760 mmHg PH2O = 47 mmHg normal = 20-65
174
What is the equation for ventilation?
PaCO2 = (VCO2 x 0.863) / VD VCO2 = alveolar ventilation VD = alveolar dead space
175
Describe the 2 types of Interval Data.
1) Discrete - integer only scale (e.g. number of toes or nostrils) 2) Continuous - constant scale interval (e.g. temperature, height, weight) more precise than discrete interval data because decimal places can be used
176
Describe the 3 types of Categorical Data.
1) Dichotomous - binary data (e.g. male/female, alive/dead) 2) Nominal - qualitative, NOT mathematical and can"t be ranked (e.g eye color, type of surgery) 3) Ordinal - data that is ranked but does not have a consistent scale interval. Used to indicate the order of a group of items, but does not indicate the degree in difference in the positions (e.g. ASA class, Mallampati class, VAS pain score)
177
What type of data is the measurement of MEAN best used in? What is the weakness of using MEAN?
Mean's best use is with Symmetric Data The weakness of using mean is Outliers
178
What type of data is the measurement of MEDIAN best used for? What is the weakness of using MEDIAN?
Median is best used to analyze Skewed Data The weakness of using median is the need for calculation and sorting
179
What type of data is the measurement of MODE best used for? What is the weakness of using MODE?
Mode is best used for COUNTS The weakness in using mode is that it can not be used in CONTINUOUS DATA because the decimals would make having a mode improbable.
180
What is population variance?
It is the average of the SQUARED deviations form the mean and allows an analysis of dispersion or variability
181
What is the standard deviation?
It is the spread, scatter or dispersion of data and allows an analysis of variance in the original units for easier interpretation
182
What percentage does 1 standard deviation have on the data?
Approximately 68% of observations are within 1 standard deviation of the mean
183
What percentage does 2 standard deviations have on the data?
Approximately 95% of observations are within 2 standard deviations of the mean
184
What percentage does 3 standard deviations have on the data?
Approximately 99.7% of observations are within 3 standard deviations of the mean
185
What is probability?
The probability of the event is the proportion of times that event occurs in MANY repeated trials. - it describes the long run regularity of random phenomena - lies between 0 & 1
186
What does a confidence interval reflect and what 3 components are necessary in order to calculate it?
A confidence interval (CI) reflects the reasonable range of values that the unknown and unknowable parameter might take on. In order to calculate CI, you must know: - sample size - sample mean - sample standard deviation CI is typically presented as the 95% (p value = 0.05) or the 99% (p value = 0.01)
187
What 4 methods can help in preventing or decreasing Type II errors?
1) Raise the level of alpha (not commonly done) [NEVER beta] 2) Reduce population variability 3) Make the difference between the conditions greater 4) Increase the sample size (the most common method used)
188
What type of test is chi-square appropriate for evaluating?
Non-parametric testing where there are 2 nominal/categorical (e.g. eye color, type of surgery) variables that are probabilistically independent - Non-parametric data tends to be weaker and less accurate than parametric data and therefore, viewed less favorably
189
What does the coefficient of determination do?
It defines the strength of the relationship between variables in a linear regression: R-square - Ranges from 0-1 - R-square of 1 means there is a perfect linear relationship - R-square of 0 means there is no linear relationship
190
What is an odds ratio?
The ratio of the odds of an event occurring in one group and the odds of it occurring in another group = event rate/ nonevent rate - odds ratio of 1 means that condition is equally likely in both groups - less than 1 means less likely in first group - greater than 1 means more likely in first
191
What is a risk ratio?
It is the ratio of risk in the experimental group to the risk in the control group RR = experimental event rate / control event rate
193
What are the 5 clinical predictors that indicate high risk of perioperative cardiac event with anesthesia?
1) Ischemic heart disease 2) compensated or prior heart failure 3) cerebrovascular disease (stroke, TIA) 4) Diabetes mellitus 5) renal insufficiency
194
What effect do benzodiazepines have on CO2?
They decrease the slope of ventilation response to CO2 NO shift in CO2 curve
195
What food allergies may have cross-reactivity with latex allergy?
Allergies to: bananas, avocado, kiwi
196
What is the Parkland formula for burns in the first 24 hours?
4ml/kg %
197
For every \_\_\_\_cm change in height (up or down) of the arterial line transducer there is a corresponding \_\_\_\_\_mmHg change in the blood pressure reading
For every 15cm change in height (up or down) or the arterial line transducer there is a corresponding 10 mmHg change in the blood pressure reading. - if the transducer is lowered, there will be an increase in the BP reading - if the transducer is raised, there will be a decrease in the BP reading
198
The O2 pressure-sensor shutoff valve requires what O2 pressure to remain open and allow N2O to flow into the N2O rotameter?
The O2 pressure-sensor shutoff valve = Fail safe valve When the O2 pressure within the anesthesia machine decreases below 25 psi, this valve discontinues the flow of N2O or proportionally decreases the flow of all gases
199
If an anesthesia machine has an incompetent pressure relief valve, what is the result to the patient?
Hypoventilation because the pressure relief valve, which should be closed during inspiration, is now open and therefore, not delivering the appropriate volumes.
200
What are the metals that are MRI safe?
Aluminum Titanium Copper Silver
201
What are the symptoms of alcohol toxicity after ablation therapy?
coughing, choking sensation, tachycardia, respiratory depression and cardiac arrest
202
What drugs are used for prophylactic treatment of patients with a history of IV contrast dye allergy?
Prednisone (40 mg) Famotidine (20 mg) Diphenhydramine (50 mg)
203
What drug is key in the treatment of IV contrast dye allergic reaction?
Epinephrine (0.5 - 1 mg) - subcutaneously for mild reactions - IV for anaphylaxis
204
What is the OSHA maximum amount of radiation exposure recommended annually?
50 mSv
205
Describe the 3 Phases of Recovery
- Phase 1: recovery room similar to PACU in OR - d/c once protective reflexes, motor function has returned - Phase 2: recovery area with limited resources (i.e. sitting in chair) - d/c when discharge-to-home criteria are met - Phase 3: at home - return to baseline preoperative physiologic state
206
What are the absolute requirements for discharge home after anesthesia?
oriented patient stable vital signs pain, nausea, vomiting CONTROLLED No unexpected bleeding able to ambulate patient has an escort home
207
What are the 2 discharge scoring systems? What is the minimum score for discharge?
1) Modified Aldrete Scoring System: \>/= 9 2) Post-anesthesia Discharge Score (PADS): \>/= 9
208
What is the VAS scoring system associated with?
Pain scoring VAS = 0-3 is minimal or no pain VAS = 4-6 is moderate pain VAS = 7-10 is severe pain
209
What age is too young for Ambulatory Surgery Centers? Too old?
- Term infant (\>36 weeks gestation): \< 8 weeks (2 months) of age - Premature infant (32-36 wks gestation): should be \>/= 52 weeks (4-5 months) of age - Micro-premature infant (\< 32 wks gestation): should be \>/= 60 weeks (7 months) of age Too old: age of \> 85 years of age
210
How long should non-emergent surgery be delayed after an episode of unstable coronary syndromes (e.g. acute/recent MI, unstable angina, new onset angina)?
- Delay surgery for 7 days after an acute MI if no further myocardium is at risk - Delay surgery for 30 days if after a recent MI with further myocardium is at risk
211
When is it safe to discontinue antiplatelet therapy after 1) balloon angioplasty 2) bare metal stents (BMS) 3) drug eluting stents (DES) 4) CABG
1) 2 weeks after balloon angioplasty 2) 4-6 weeks after BMS 3) 12 months (1 year) after DES 4) 30 days (1 month) after CABG
212
What is the highest SBP and DBP acceptable to begin an elective surgery?
Reasonable control with an SBP \< 180 mmHg, DBP \< 110 mmHg
213
What are the anesthetic benefits of smoking cessation at 6 months, 6-8 weeks, 3 weeks, 1 day?
- 6 months: restoration of antimicrobial and inflammatory alveolar macrophage function - 6-8 weeks: improved pulmonary function and decreased wound-related and cardiovascular complications - 3 weeks: reduced incidence of impaired wound healing - 1 day: reduced nicotine, carboxyhemoglobin blood concentrations improving tissue oxygen delivery
214
What factors are considered in the ASA's practice guidelines for the perioperative management of OSA?
- amount of narcotic anticipated postoperatively - type of anesthetic - AHI (apnea/hypopnea index measured on a sleep study)
215
What are the simplified risk factors for PONV?
- female gender (of no concern in pediatrics) - post-op opioid use - non-smoking - history of PONV/motion sickness
216
What are other (non-major) risk factors for PONV?
- duration of surgery \> 60 mins to 180 minutes - anxiety - inhalational anesthetics - young age - history of migraines (avoid drugs associated with 5 HT3 i.e. ondansetron) - pain - coexisting medical conditions - nitrous oxide
217
What are surgical risk factors for PONV?
- lower abdominal - middle ear - tympanoplasties and adeno-tonillectomies in children - gynecological and laparoscopic surgery \* - plastic surgery (especially breast) \* - strabismus surgery
218
Flexion of the neck while the ETT is in place will cause what type of shift of the ETT? with extension?
The ETT will deepen and may move from the trachea into a main bronchus due to an upward shift of the carina with flexion of the neck or a change from the supine to a head down position. Therefore, with extension, the opposite will occur and the ETT will cephalad and possibly into the pharynx
219
What is the minimum flow rate a vaporizer needs in order to achieve adequate output?
For a sufficient vaporizer output, the flow rate needs to be at least 250 mL/min in order to the advance the molecules of the volatile agent upward
220
What is the maximum FiO2 that can be delivered via nasal cannula?
0.45 The rule of thumb is that FiO2 increases by 0.04 for each L/min increase in O2 via nasal cannula up to a maximal FiO2 of ~0.45
221
Increasing the frequency of an ultrasound transducer will do what to penetration and resolution?
The penetration will decrease (be lower) and the resolution will be high
222
What color is associated with a compressed gas cylinder filled with helium? nitrogen? carbon dioxide? nitrous oxide? air? oxygen?
Helium = Brown Nitrogen = Black Carbon dioxide = Gray Nitrous oxide = Blue Air = Yellow (U.S.) & White or Black (international) Oxygen = Green (U.S.) & White (international)
223
What statistical test is best for analyze data from a study that involves only 2 possible values (dichotomous data: i.e. benefit vs. no benefit)?
Chi-square test
224
What are the 5 criteria of the Post-Anesthesia Discharge Scoring System (PADSS)?
1) Vital signs 2) Ambulation 3) Nausea/vomiting 4) Pain 5) Surgical Bleeding Each variable is scored from 0-2 A score of 9 is acceptable for discharge
225
What circuit is the Pethick test used to test the integrity of?
The Bain circuit, which has a unique hazard of occult disconnection or kinking of the inner, fresh gas delivery hose - To perform this test, the patient's end of the circuit (at the elbow) is occluded; the APL valve is then closed; the circuit is filled using the O2 flush valve; the occlusion is released and the flush is pressed. - venturi effect flattens the reservoir bag if the inner tube is patent
226
What are some of the main discharge criteria for patients who receive regional anesthesia that differs from patients who have general anesthesia?
- Patients should be able to ambulate - It is advisable for these patients to be able to void before discharge - Motor and sensory function returns before sympathetic nerve function, therefore, it is not enough for the patient to be able to ambulate, but they also need to be able to void.
227
What ambulatory surgeries have an increased risk of PONV?
- lumpectomy - septal nasal submucosa - tonsillectomy and adenoidectomy - rotator cuff repair - laparoscopic cholecystectomy - knee arthroscopy
228
What are signs of adequate recovery from neuromuscular blockade?
- TOF ratio or 0.9 - 1 - Probability of detecting adequate reversal with a tetanus test of 100 Hz showing no fade is 66%
229
What is the NYHA classification system for functional status?
- It serves as a predictor of survival - Class I: no limitations - Class II: slight limitation, comfortable with mild exertion - Class III: marked limitation, comfortable only at rest - Class IV: any physical activity at all brings on symptoms, plus symptoms occur at rest
230
What does Boyle's Law state? What is it used for?
It states that for a fixed mass of gas at a constant temperature, the product of pressure and volume is constant. - the concept is used to calculate the volume of gas remaining in a cylinder by measuring the pressure.
231
What does Graham's Law state?
It states that the rate of diffusion of a gas is inversely proportional to the square root of its molecular weight
232
What is beneficence?
It obligates investigators to protect persons from harm by maximizing anticipated benefits and minimizing risks of harm that are involved in the research study
233
If the anesthesia machine has a check valve, what type of pressure test should be performed?
A NEGATIVE pressure test is needed - the bulb should stay collapsed just 10 seconds
234
What does the color on the CO2 colorimetric device (i.e. litmus device) indicate?
- Purple: EtCO2 \< 0.4% and tube is probably NOT in situ or that CPR is not successful - Tan: EtCO2 = 0.4- 2% and tube is in situ but that cardiac output is low or that the CPR is inadequate - Yellow: tube is in situe and that there is adequate lung perfusion/ adequate CPR
235
What effect will very low vs. very high fresh gas flow have on vaporizer output of inhaled anesthetics? Why?
1) Very low FGF rates will result in a decrease in vaporizer output due to insufficient upward mobilization of the vapor molecules 2) Very high FGF rates will result in a decrease in vaporizer output as well, due to incomplete mixing
236
How does the use of N2O in fresh gas flow affect vaporizer output?
N2O decreases vapor output because some of the N20 goes into the vaporizer and solubilizes in the liquid anesthetic and isn't available as a carrier gas, therefore, that gas composition will initially decrease the amount of volatile anesthetic output (then it will normalize).
237
If vaporizer is tipped over, what should be done?
The system should be flushed for 30 minutes at HIGH flow rate with LOW dialed setting to avoid overdose
238
At high altitudes, what is the appropriate management when trying to achieve 1 MAC of isoflurane/sevoflurane anesthesia? desflurane?
1) For isoflurane/sevoflurane, which are carried in a variable bypass vaporizer, the concentration dial should be set to 1 MAC (NOT higher or lower) due to the decrease in atmospheric pressure and the fact that more Iso/Sevo vaporizes (where 2% becomes 4%): - at sea level: 2% (760 torr) = 15.2 torr - at high altitude: 4% (380 torr) = 15.2 torr 2) For Desflurane, the concentration dial should be set HIGHER than 1 MAC because the vapor chamber for desflurane is closed to the atmosphere, therefore, although atmospheric pressure has decreased (760 to 380 torr), the amount you set is the amount that is delivered : - at sea level: 6% (760 torr) = 45.6 torr - at high altitude: 6% (380 torr) = 22.8 torr
239
Describe the common toxicities to Halothane? Desflurane? Sevoflurane? Methoxyflurane?
1) Halothane: undergoes extensive hepatic oxidation (the most metabolized volatile agent) and produces Trifluorocitic Acid (TFA), which upon 2nd exposure to halothane can lead to AUTOIMMUNE HEPATITIS via an IgG mediated response. 2) Desflurane: generates the most amount of CARBON MONOXIDE (CO) triggered by low flows, heat, dry absorbant, and baralyme. 3) Sevoflurane: generates COMPOUND A which is promoted by low flows, heat, dry absorbant, and baralyme and can lead to renal failure via ATN. Can also cause CANISTER FIRE because is generates the most amount of heat amongst all the volatile anesthetics. It also generates some FLUORIDE, which can also lead to POLYURIC RENAL FAILURE. 4) Methoxyflurane: undergoes hepatic degradation which produces FLUORIDE leading to POLYURIC RENAL FAILURE
240
Describe phases 0 - IV on the Time & Volume Capnograph
* Phase 0: the onset of inspiration (the downslope)
* Phase I: Pco2 is 0 as it reflects the exhaled gas from the large airways (dead space)
* Phase II: the transition between airway and alveolar gas (mixture of dead space and alveolar gas)
* Phase III: (i.e. alveolar plateau) is normally flat
* Phase IV: peak Pco2 level (end tidal Pco2
241
What is the most common method to detect CO2 in the operating room?
Infrared absorptions spectrophotometry (IRAS) devices can detect CO2, N2O, and the potent inhaled anesthetic agents
242
What percent sensitivity will continuous monitoring of leads II and V5 result in the detection of myocardial ischemia?
80%
243
Describe the possible pathophysiology/ diseases that may be respresented by the pressure-volume loops (Starling Curve) below:
* Blue Loop: Normal
* Yellow Loop : Significant Hypovolemia or Mitral Stenosis (underfilled ventricle and under-pressurized)
* Red Loop: Aortic Stenosis
* Green Loop: any Regurgitant Lesion
244
What are the weights (kg) associated with LMA sizes 1-3?
1: \<5 kg
1. 5: 5-10 kg
2: 10-20 kg
2. 5: 20-30 kg
3: 30-50 kg
245
What do the colors of the carbon dioxide colorimetric device indicate?
| (purple, tan, yellow)
Purple: etCO2 is \< 0.4% and most possibly the ETT is NOT in situ or cardiopulmonary perfusion (CPP) is NOT successful
Tan: etCO2 is 0.4 - 2% and the ETT is in situ but CO is low or that CPR is inadequate
Yellow: ETT is in situ and adequate lung perfusion/CPR
246
What is the equation for power?
Power = 1-ß
if the probability of making a beta error (falsely accepting the null hypothesis) is high, it would decrease the power of a study
247
Surgeries with increased risk of PONV
1. lumpectomy
2. resection of septal nasal submucosa
3. tonsillectomy and adenoidectomy
4. rotator cuff repair
5. laparoscopic cholecystectomy
6. knee arthroscopy
248
What additives allow blood (PRBCs) to be stored for 21 days? 35 days? 42 days? 10 years?
* 21 days: CPD, ACD, and CP2D solutions
* 35 days: CPDA-1 solution
* 42 days: ADSOL extends the life of the unit of PRBCs
* 10 years: frozen
249
What coagulation factors are NOT produced by the liver?
Factor VIII and vWF are endothelium derived procoagulant factors
250
How is Factor VIII replaced and what are the goals? (prior to surgery, post-operatively, upon discharge)
Replacement therapy goals are to obtain a level that will ensure adequate hemostasis (100% at the start of a major surgical procedure), then maintain a trough level of 50-60% (max of 75%) until discharge
* For 100% replacement: Give 50 µg/kg
* Post-op - discharge: 25 µg/kg q 12 hrs with qam trough level (prior to infusion)
* Discharge: 50 µg/kg q day for 1 week
