Principles of Anesthesia Practice I Unit III Flashcards
1
Q
What quick method of cylinder identification is required for gas cylinders?
A
Standard color identification
2
Q
What are the non-liquified gases?
A
Oxygen, air and helium
3
Q
What are the liquified gases?
A
Nitrous oxide and CO2
4
Q
What is the definition of a liquified gas?
A
A gas that becomes liquid to a large extent in containers at ambient temperature and at pressures from 25-1500psi
5
Q
What is the definition of a non-liquified gas?
A
Non-liquified gas: A gas that does not liquefy at ordinary ambient temperatures regardless of the pressure applied
6
Q
What does the FDA, DOT and OSHA concern themselves with when it comes to gas cylinders?
A
FDA = purity, only so much detritus is allowed in each cylinder
DOT = marking, labeling, storage, handling
OSHA = employee safety
7
Q
What components make up the body of the cylinder?
A
Steel, steel carbon fiber or aluminum body, flat or concave base and a neck with screw threads
8
Q
What is the purpose of the check valve? What is it commonly made out of?
A
Attached to the neck, is made of bronze or brass and allows for refilling and discharge of gas
9
Q
What is the purpose of the cylinder handle?
A
Opens/closes the cylinder
It is a requirement that a handle should be attached/close to every cylinder
10
Q
What is the pressure relief device (safety relief)?
A
A vent that allows the cylinder contents to be released to atmosphere if pressure increases to dangerous levels
11
Q
What are some examples of pressure relief devices?
A
A disc that bursts, a fusible plug that melts or a valve that opens
12
Q
Describe how the pin index safety system works
A
Each cylinder has an arrangement of pins that only allow connections to the appropriate points. Such as oxygen have pins at positions 2 and 5, and N2O having pins at 3 and 5
13
Q
What is the relationship of cylinder lettering to size?
A
A is the smallest and increases with subsequent letters, so A < B < C and so on
14
Q
What are D cylinders commonly used for? E?
A
D = transport, E = commonly used on anesthesia machines
15
Q
What happens to the pressure in a cylinder as the volume of a non-liquefied gas decreases?
A
Direct relationship; as the volume of a non-liquified gas decreases pressure will decrease (so as volume goes down, PSI goes down)
16
Q
What happens to the pressure in a cylinder as the volume of a liquefied gas decreases?
A
There is a mix of liquid and gas in the cylinder. As you release gas, some of the gas will move from the liquid state to the gaseous state. PSI in the cylinder will NOT begin to drop until all the liquid gas is gone
17
Q
What are the DOT requirements for gas cylinder quality/safety standards?
A
Service pressure
Test date
Diamond shaped label indicating hazard of gas…danger, warning, or caution
Name and address of manufacturer
Expiration date of contents
18
Q
What are the basic cylinder standards?
A
Valves, regulators, gauges never come into contact with oils, greases, lubricants
Never subject to temps above 54 C (130F)
Connections always tight
Never cross use hoses, regulators, gauges
Markings, labels must not be altered
Cannot be dropped, drug, slid
Valve kept closed at all times
Properly secured to prevent fall
19
Q
What are the basic requirements for storage rooms that house gas cylinders?
A
Adequate ventilation
Signs “no smoking” “no combustibles”
Not exposed to corrosive chemicals, fumes
Stored upright in bins
Full separated from empty
Wrapping, drapes undesirable
20
Q
What steps should be taken before/during use of a gas cylinder?
A
Label, pin index holes, regulator, valve outlet inspected
Check if the tamper seal has been removed
Washer in place
Open valve before bringing cylinder to pt
Face valve outlet away from people
Open slowly
Check service pressure
Correct leaks if any
21
Q
Describe how gas is delivered throughout the hospital (there are 3 primary points)?
A
Starts at central supply, when then sends it through piping at around 50 PSI which then arrives to the terminal units also at around 50 PSI
22
Q
What is the basic location of a central supply for gas?
A
It is either outdoors in an enclosure or indoors in a secure area.
23
Q
What are the requirements for a gas bank?
A
Must have 2 day supply and have a primary and secondary bank
the reserve supply may be in a secondary location
24
Q
What size cylinders is gas supply generally stored in?
A
G or H cylinders that are refilled on site
25
Why is liquid supply of a gas generally more favorable to use?
Less expensive and more convenient to store, it is refilled from supply trucks and has no interruption to service in the hospital
26
What are the classes of piping?
Main lines: connect gas source to risers
Risers: vertical pipes connecting main line with branch lines on each level of the facility
Branch: sections supplying a room or group of rooms on one level of the facility
27
What are the requirements for area alarm systems?
Found in critical life support
areas
Alarms if pressure increases/decreases 20% from normal line pressure
Must be audible and visible
Must be labeled for gas and area
Must alarm in at least 2 places, usually Maintenance/engineering, and the affected unit
28
What are the terminal units?
The point in piped gas distribution where user connects/disconnects by hose
29
What system is used to make sure the terminal units are connected to the appropriate hoses?
The diameter index safety system (DISS) or quick connects (this is what you likely commonly used in the ICU)
*this system works because the nipple and nut vary in bore/diameter of each individual connection for each gas*
30
What is the advantage/disadvantage of quick connectors?
Pro = Quick connection with one or both hands without tools
Con = Leaks more
31
What are the 2 basic functions of a vaporizer?
To change a liquid anesthetic to a vapor and to add a controlled amount of that vapor to a fresh gas flow in the breathing system
32
Most modern volatiles exist in the liquid state at what temperature?
Below 68 F (20 C)
33
What creates vapor pressure?
The molecules of the gas colliding with the container walls
34
What is saturated vapor pressure?
When equilibrium is achieved from the liquid/gas phases of the volatile. The pressure comes from the vapor colliding with the walls of the container
35
What factors can changed the saturated vapor pressure?
The characteristics of the liquid and the temperature of the liquid
*These factors are independent of atmospheric pressure*
36
What are the definitions of partial pressure and volumes percent
PP = the pressure of a singular gas in a mixture of several gases
VP = is similar to above, but its the concentration of a gas in a mixture expressed as a percentage
*VP = partial pressure / total pressure x 100%*
37
What is the vapor pressure of Halothane (Fluothane)?
243
38
What is the vapor pressure of Isoflurane (Forane)?
238
39
What is the vapor pressure of Desflurane (Suprane)?
669
40
What is the vapor pressure of Sevoflurane (Ultane)?
157
41
What is the heat of vaporization?
The number of calories needed to convert 1 gram of liquid into vapor
42
What happens to the liquid as the equilibrium shifts to move more molecules into the gaseous state from the liquid state as gas is allowed to leave?
The liquid temperature drops causing vapor pressure to drop and the output of vapor decreases
43
What is specific heat?
The number of calories needed to raise the temperature of 1 gram of something by 1 degree C
44
What is the relationship of specific heat to the amount of heat absorbed?
The higher the specific heat, the more heat required to raise the temperature of the substance
45
What is the specific heat of water?
1 cal per gram
46
Why are materials with higher specific heat's generally used when making the container to house a vaporizer?
Materials with higher specific heat minimize temperature variations
47
What is thermal conductivity?
The speed at which heat flows through a substance
*The higher the thermal conductivity, the better the substance conducts heat, so a metal has high thermal conductivity*
48
What metals, per lecture, have high thermal conductivity and therefore minimize temperature swings during vaporization?
Copper and aluminum
49
What is the most common vaporizer?
Concentration calibrated variable bypass
50
Where should the vaporizer be located?
Between the flow meter and common gas outlet
51
Why should the vaporizer not be downstream of the common gas outlet?
They are not calibrated for high flows of oxygen flush
52
How do you adjust how much anesthetic is delivered with variable bypass?
By adjusting the splitting ratio (the more you turn the knob from 0 to higher numbers you increase the splitting ratio)
53
How does a vaporizer compensate for temperature fluctuations as liquid anesthetic is converted into vapor?
As you lose liquid, the change in temperature causes the temperature compensating valve to move, this automatically changes the splitting ratio to compensate for the decrease in volatile being delivered by increasing the splitting ratio
*as temperature decreases, vapor pressure decreases and less volatile gets delivered. The automatic increase in splitting ratio compensates*
54
What color identifies Isoflurane, Sevoflurane and Desflurane?
Sevo = yellow
Iso = purple
Des = blue
55
It is highly unlikely to have the incorrect agent in a vaporizer, but what safety measure would indicate that this has occurred?
You would see 2 different vapor pressures on the monitor
56
What do you do to the vaporizer if the incorrect agent has been added to it?
It must be completely discarded/drained. Then run FGF until there is no vapor detected
57
What is the ideal FGF rate for variable bypass?
250 ml/min to 10 L/min
58
What happens with low flow rates in the vaporizer? High rates?
Low = The high density of volatile prevents upward movement of molecules
High = failure to saturate carrier gas
In both cases, lower levels of volatiles are delivered to the patient than what is dialed on the vaporizer
59
The pumping effect causes intermittent back pressure in the circuit. What 2 phenomena can cause this?
Positive pressure ventilation and the oxygen flush valve
*more pronounced with low FGF, low dial settings and low levels of liquid in the vaporizing chamber*
60
What measure helps attenuate the pumping effect?
Smaller vaporizing chambers, baffle systems, longer tube for the inlet of vaporizing chamber and the addition of a check valve
61
Throughout anesthesia, when is little to no rebreathing desired? When is rebreathing desirable?
No rebreathing = emergence
Rebreathing = induction
62
What is the relationship of FGF to inspired concentration?
High FGF - inspired concentration = the vaporizer setting
Low FGF - the inspired concentration is different than the vaporizer setting
63
What is the relationship of vapor pressure to barometric pressure?
They are independent of each other (because the vaporizer is generally calibrated to it's anticipated altitude)
64
When is tipping most likely to occur?
When the vaporizer is incorrectly removed, transported or replaced
65
What occurs when tipping happens?
Excess liquid enters the bypass chamber which causes a very high output of volatile = the patient can get an overdose of volatile
66
Why is overfilling highly unlikely to occur in modern vaporizers?
Modern vaporizers have an overflow hole to allow excess volatile to drain
67
Common cause of vaporizer leaks?
Loose filler caps, drain valves or vaporizer/mounting bracket interface
*when this occurs, there is usually an odor to the cause you can smell*
68
What happens to the Fi if there is a vaporizer leak?
Fi is the inhaled concentration or fraction of the gas, if there is a leak, less gas gets to the patient and can result in patient awareness
69
What are the basic vaporizer standards?
Average concentrations +/- 20% of setting
Gas may not pass through more than 1 vaporizer
Vaporizer interlock
Output of vaporizer <0.05% in OFF
All control knobs move counterclockwise
Filling levels displayed
70
What are the mounting standards for vaporizers?
Detachable - Standard on most machines and the weight of vaporizer and “O” ring create seal
Locking lever on back (front for cannisters)
Easily removed and replaced (esp. for MH)
71
What device prevents more than 1 vaporizer from being turned on at one time?
The interlock device
72
Where would you find the holes for the pin index safety system?
On the cylinder valve positioned in an arc below the outlet port
73
What vaporizers include a transport dial to isolate the vaporizer and bypass chamber?
Some Drager vaporizers
74
When were the first anesthesia machine standards implemented? Last update?
1979 and last update was in 2005
*American society for testing and materials oversees this*
75
What are the basic functions of the anesthesia machine?
Provide accurate and safe gas delivery
Provide a means for ventilating patients
Provide electrical outlets
Provide a housing for monitoring devices
Provide storage/shelving
76
What functions are activated when the master switch is on?
Pneumatic and electrical functions
Activates alarms and safety features
Power-up protocol can be bypassed
77
What functions are not disabled when the master switch is turned off?
The battery charger, electrical outlets, oxygen flush valve and the auxiliary oxygen flow meter will all still function
78
What are the basic requirements of the power failure indicator? Recommendations for safe practice?
The alarm must be visual and/or audible. For safe practice, keep the machine plugged in with the battery backup fully charged
*Duration of backup depends on power usage, such as are we manually ventilating or automatically ventilating*
79
What is the primary purpose of the electrical outlets on the anesthesia machine?
To power anesthesia monitors. Any other appliances should be plugged into the main hospital outlets
80
What occurs if electrical requirements/demands exceed the anesthesia outlet?
Circuit breaker activates and the machine will turn off
81
What are the 3 pneumatic systems?
High pressure, intermediate pressure and low pressure
82
Where does the high pressure system receive gas and at what pressure?
From the cylinders at high variable pressure, around 2200 PSI
83
How does the high pressure system convert high pressure gas to a more manageable PSI?
Using the pressure regulator (1st stage regulator) to reduce it to a lower more constant pressure of ~45 PSI
*Without the regulator, our flow would constantly be changing*
84
We are required to have yokes for what gas cylinders?
Oxygen and nitrous
85
What are the basic functions of the hanger yoke?
Orients and supports cylinder
Provides a gas-tight seal
Ensures a unidirectional flow
86
What parts make up the hanger yoke?
Body - principal framework
Retaining screw - tightens cylinder (clamp)
Nipple - thru which gas enters machine
Index pins- prevents attaching an incorrect cylinder
Washer - forms seal between cylinder and yoke
Check valve assembly - ensures unidirectional flow
87
What is the purpose of the check valve assembly?
To prevent gas from exiting the machine when there is no cylinder in the yoke. It also prevents gas moving from a cylinder with higher pressure to one with lower pressure
*The prevention of gas movement between cylinders only occurs if both cylinders have a yoke and are on*
88
What is a monitoring requirement for each gas being supplied by the cylinders?
Each must have a cylinder pressure indicator
89
What is the mechanism that enables analogue pressure devices to monitor pressure?
Bourdon tubes - as pressure changes, it increases/decreases the curve of the tube. This change in curvature is transmitted to the gauge to give us a pressure reading
90
What are the 2 units of measurement that a pressure gauge may be calibrated to?
kPa - kilopascals
PSI - pounds per square inch
91
What areas of the anesthesia machine make up the intermediate pressure system?
Pneumatic part of master switch
Pipeline inlet connections and indicators
Piping
Oxygen pressure failure devices
Oxygen flush valve
Flow control valves
92
What is the PSI in the 1st stage regulator? In the pipeline?
1st = PSI of 45
Pipeline = PSI of 50 - 55
93
What is the intermediate pressure if the master switch is off?
Zero
94
What are 2 basic requirements for pipeline pressure indicators?
Indicator required for each gas monitored
Usually found on front of anesthesia machine
95
Why must the pipeline pressure indicator be upstream of the cylinder valve?
If both are open, and the indicator is downstream, you would get an adequate pressure reading until the cylinder is empty, meaning both the pipeline and the cylinder are empty and you have no backup
*if the indicator is appropriately upstream, then as soon as you lose pipeline pressure you would see the alarm, start gas from the cylinder, then take the appropriate steps to fix the problem*
96
How much pressure should the anesthesia machine piping be able to withstand?
4x the intended pressure
97
What is the acceptable leak rate inside the machine?
no more than 25 ml/min
98
At what PSI is the oxygen failure safety device tripped?
At PSI less than 30
99
What occurs if oxygen pressure drops below 30 PSI?
Nitrous use is decreased or stopped (if nitrous is running), 19% oxygen concentration is maintained, the alarm sounds within 5 seconds and continues until oxygen flow ceases
100
What are the basic requirements for the oxygen flush?
Operable with 1 hand
Single purpose
Self-closing
Designed to minimize accidental use
Have flow between 35-75 L/min
101
What are the risks of the oxygen flush valve?
Barotrauma and surgical awareness (the high flow rate dilutes the anesthetic)
102
What are the basic requirements for the oxygen flow knob?
It must be larger and fluted so that it looks and feels different from the other knobs
103
What regulates the flow of oxygen, air and other gases?
Flow adjustment control mechanisms - think knobs for the flowmeters
104
What components make up the low pressure system?
Everything downstream of flow control devices:
Flowmeters
Hypoxia prevention devices
Unidirectional valves
Pressure relief devices
Common gas outlet
105
What is the pressure in the low pressure system?
Variable, though should be slightly above atmospheric
*Depends on flow from flowmeters and backpressure from breathing circuit*
106
What tube is used in flowmeters?
A Thorpe tube
107
What makes up a Thorpe tube?
Smallest diameter at bottom
Free floating indicator
A stop at top of tube
A flow scale
108
What safety measures must be in place on a flow meter?
Marked with the appropriate color and chemical symbol
109
What pressure does the 2nd stage regulator maintain?
14 - 30 PSI (remember, 1st stage is about 45 PSI)
Smallest diameter at bottom
Free floating indicator
A stop at top of tube
A flow scale
110
Describe the general trend of gas movement in the anesthesia machine
It goes from bottom to top, and from left to right
*this basic setup means that flowmeters should be placed on the right side*
111
Why does flowmeter sequence matter?
Gas should flow from left to right; if a leak occurs in the gas to the far right, all gases behind it will fail/leak as well. So if oxygen is on the far left, and a leak occurs to the right, the patient may get a hypoxic gas mixture. If the oxygen is to the far right, and a leak occurs to the left, oxygen should remain unaffected
112
What is the mandatory minimum oxygen flow for the flow meter?
50 - 250 ml/min
*only when the master switch is on*
113
When does the minimum oxygen ratio activate when using oxygen and nitrous?
When the oxygen concentration drops below 25%
114
Where are the unidirectional valves located?
Between the vaporizer and the common gas outlet, upstream from the oxygen flush valve
115
In terms of unwanted pressure, what is the function of the unidirectional valves?
Lessens back pressure from flush or breathing circuit
116
Where would you find the pressure relief devices?
Near the common gas outlet.
117
What is the function of the pressure relief devices?
Opens to atmosphere and vents if preset pressure is exceeded
Limits ability of machine to provide adequate pressure for jet ventilation
118
What is the basic function of the common gas outlet?
Receives all gases from machine and delivers mixture circuit
*should not be used for supplemental oxygen and should also be made difficult to disconnect*
119
What is the definition of a ventilator?
Automatic device designed to provide/augment ventilation and oxygenation
120
What does the ventilator replace or override on anesthesia workstations?
The reservoir bag
121
What was the primary method of ventilation on older ventilators? What are its drawbacks?
Controlled mandatory ventilation (CMV)
It couldn't provide high enough inspiratory pressure, couldn't provide PEEP and offered only volume control ventilation
122
What type of ventilation has a decrease in Vt if the compliance of the breathing system decreases?
Volume control
*volume is used to expand system, and if it takes more volume to overcome a less compliant system, you would lose volume*
123
How do modern vents account for changes in volume delivered related to changes in system compliance?
By using pressure controlled ventilation
124
What is peak pressure?
maximum pressure during the inspiratory phase time
125
What is the relationship of FGF to Vt on older vents?
As FGF increases, Vt increased
*newer vents divert excess FGF during inspiration*
126
What is the time during which lungs are held inflated at a fixed volume/pressure?
The inspiratory pause time
127
What is the normal and inverse I/E ratios?
Normal = 1:2, inverse = 2:1
128
What allows excess gas to be sent to the scavenger during exhalation?
The spill valve
129
What allows the driving gas to exit the bellows housing?
Exhaust valve
130
What are the 2 primary factors that affect ventilation?
Compliance of the system and of the patient
131
Why does a leak decrease Vt?
The vent cannot compensate for a leak
132
What type of bellows is most common? Why?
Ascending; it's harder to detect problems with descending (gravity will always pull it down), whereas if there is a problem with ascending you can clearly see the fail to rise
133
Describe when the bellows ascend/descend for ascending (standing) or descending (hanging) bellows
Ascending: rise on expiration, descend on inspiration
Descending: rise on inspiration, descend on expiration
134
What physiologic problems may occur if there is a hole in the bellows?
Alveolar hyperinflation/barotrauma
135
What happens to the gas if the scavenging system is closed?
Waste gas is vented to the room
136
What system uses 2 circuits in the ventilator? Which uses 1?
2 circuits = bellows
1 circuit = piston
137
What are some of the basic characteristics of piston ventilators?
Mechanically driver motor, no driving gas, uses dramatically less gas and doesn't alter Vt based on compliance (small piston chamber, accurate Vt, hidden on machine and very quiet)
138
What are the primary problems with piston ventilators?
Refills even with disconnection and can entrain room air during leaks (which dilutes oxygen/volatiles)
139
What is the most commonly used ventilator mode?
VC or volume control
140
Describe VC ventilation
you use a set Vt, RR and I:2 ratio, and additional breaths are of the programmed Vt
141
Describe PC ventilation
You use a set PIP, RR and I:E and the Vt changes with each breath d/t changes in resistance and compliance
*can cause atelectasis and hypoventilation*
142
Describe how volume guarantee pressure control works
It's a hybrid of VC and PC; it maintains Vt by adjusting PIP over several breaths, this prevents sudden changes to Vt d/t changes in compliance
143
Describe AC ventilation
A determined negative pressure from the patient triggers each breath to a set Vt
144
Describe intermittent mandatory ventilation
A mandatory number of breaths are set, but additional native breaths at a variable Vt are permitted. This can lead to breath stacking
145
Describe SIMV
Synchronizes ventilator driven breaths with spontaneous breaths, acts as a backup to weaning the ventilator
146
Describe pressure support
PIP and inspiratory time are set, but Vt is entirely reliant on native effort, so an apnea alarm is required
147
What material are MRI compatible breathing systems generally made out of?
Aluminum
148
What are some common reasons for ventilatory failure?
Disconnection from power supply
Extremely high FGF
Fluid in electronic circuitry
Leaking bellows housing
149
2 common causes for loss of breathing system gas?
Failure to occlude spill valve or a leak in the system
150
What are some common causes for incorrect settings on the vent?
Inadvertent bumping
Not adjusted for new case
Not adjusted for position/pressure changes
Ventilator turned off for xrays
151
Pros/cons of the ventilator?
Pros: anesthesia can be lazy! In all seriousness, it allows anesthesia to focus on other tasks, decreases fatigue and produces a more regular rate/rhythm and Vt
Cons: loss of "feel", older vents may lack desired mode, components are hard to clean/fix, not user friendly, noisy or too quiet, may require driving gas (expensive)
152
What ppm would 100% oxygen be? 1%?
100% = 1,000,000 ppm
1% = 10,000 ppm
153
What areas tend to have higher levels of trace gas concentrations?
Pediatric anesthesia, dental surgery and poorly ventilated PACUs
154
What is the maximum concentration of trace nitrous oxide allowed in an OR? Dental facility?
OR = 25 ppm
Dental = 50 ppm
155
Common causes of operating room contamination?
Failure to turn off vaporizer
Poorly fitting masks
Flushing circuit into room
Filling vaporizers…spills
Use of uncuffed ETT
Scavenging system leaks
156
What are some of the health concerns related to exposure to trace anesthetic gases?
Spontaneous abortions
Spontaneous abortion in spouses
Infertility
Birth defects
Impaired performance
Cancer/mortality
Liver disease
Cardiac disease
157
Describe a passive ventilation system
Attached to room ventilation system and as air flows it filters/gets rid of anesthetic gas from disposal tubing going from the anesthesia machine to the exhaust grill. While economic, it is less common than active ventilation
158
Describe an active ventilation system
Attached to a central vacuum, it must be able to provide high volume of 30 L/min suction and needs plenty of suction outlets that are close to the anesthesia machine
159
What work practices can help minimize trace gas contamination?
Ensure proper mask fit
Turn off gas flow (not vaporizer) during intubation
100% wash out at end of case
Prevent liquid spills
Place anesthesia machine as close to exhaust grill (passive system) as possible (and if present)
160
What are some causes of hypoxic inspired gas mixture?
Incorrect gas in the pipeline
Incorrectly installed outlets
Oxygen tubing or hoses attached to incorrect flow meter
Incorrect cylinder attached to yoke
Incorrect cylinder - minimized from color standardization
Flow control malfunction
Leak in oxygen flow meter
161
What are some causes of hypoventilation?
Insufficient gas (pipeline failure or cylinder being empty)
Obstruction
Leaks
Main machine power off
Breathing system leaks (from absorbent, connectors, gas sampling or general disconnect)
162
What occurrence can block the inspiratory/expiratory paths?
Plastic from the mask or absorbent wrapping causing an occlusion
*the example from lecture, is a common method of signaling the current circuit is clean is stuff some of the plastic that wrapped the mask into the mask itself. Some of that plastic can get into the circuit and partially block it*
163
Common hypercapnia causes related to the vent?
Hypoventilation
Absorbent failure
Excessive dead space
Defect coaxial system
164
Common causes of anesthetic agent overdose?
Tipped vaporizer
Vaporizer accidentally on
Incorrect agent in vaporizer
Interlock system failure
Overfilled vaporizer
165
When can inadvertent exposure to volatiles occur?
Change breathing system hoses and bag
Change fresh gas supply hose
Change absorbent
Use very high oxygen flows to flush machine
Remove vaporizers
Use axillary flowmeter for supplemental oxygen
166
What type of vaporizer does not have a splitting ratio?
Bubble-through
167
Why does CO2 insufflation of the belly cause an increase in BP?
It stimulates the release of catecholamines and vasopressin along with compression of the arterial vasculature
168
What is the IAP goal?
Less than 20 mmHg, though ideally you want it closer to 12-15 to minimize side effects
169
What are pulmonary effects of CO2 insufflation?
Increased PaCO2, decreased compliance by 30 - 50%, increased PIP, decreased FRC and development of atelectasis
170
How does CO2 insufflation increase PaCO2?
Some of the gas gets absorbed by the body which then increases PaCO2. This increase plateaus in 10 - 15 minutes
171
What is the difference in treatment of elevated PaCO2 d/t CO2 insufflation in the early vs late stage of a case?
Early = treat, such as by increasing minute volume
Late = you may elect to not treat it because you'll be waking up soon and that elevated CO2 could help stimulate the drive to breathe
172
What position should you get the patient into if a gas embolism is suspected?
Trendelenburg with left lateral tilt
173
What steps need to be taken if subQ emphysema occurs?
In general, just monitor ventilation/oxygenation. The emphysema should be transient and resolve in 30 - 60 minutes
174
Describe the gas lock phenomena
This is when the gas in the blood stream creates a barrier in the vena cava which decreases venous return
175
What s/sx and clinical findings may support the diagnosis of gas embolism?
Tachycardia
Cardiac dysrhythmias
Hypotension with increased CVP
Millwheel murmur
Hypoxemia
Decreased ETCO2
176
Treatment of a gas embolism?
Cessation of insufflation/release of pneumoperitoneum
Trendelenburg (with left lateral tilt), fluid bolus, 100% O2
Aspiration of air (requires a central line)
Vasopressor support
177
At what IAP do hemodynamic effects begin to occur?
Greater than 10 mmHg
178
What are some hemodynamic effects of elevated IAP? Treatment?
Decreased CO proportional to the IAP, increased arterial pressure and increased SVR/PVR
Tx = increase vapor, nitro, cardene or remifentanil
*these CV effects are generally short lived and should not need drug intervention. If intervention is warranted, dose with care d/t the short lived nature of the CV effects*
179
Which of the following can affect cardiac arrhythmias: increased PaCO2, peritoneal stretch, electrocautery/stretch of the fallopian tubes
Peritoneal stretch and electrocautery/stretch of the fallopian tubes. You can treat the elevated HR with glycopyrrolate and try to limit insufflation pressure
180
What is the common cause of a brachial plexus injury?
Overextension of the arm
181
Most commonly injured nerve in lithotomy position?
Peroneal nerve
*compartment syndrome is also a concern*
182
Why has laparoscopy become the first choice rather than laparotomy?
It has more rapid recovery, better maintenance of hemostasis, less risk, less pain, less PONV and less pulmonary dysfunction
183
What is the most common injury from laparoscopy?
Intestinal injury (perforations, CBD injury). Other injuries: vascular injury, burns and infection
184
Contraindications to laparoscopy?
Increased ICP, tumor, trauma, hydrocephalus
185
Is LMA or GETA more common in laparoscopy?
GETA
186
Is an OGT or NGT more common in laparoscopy?
OGT is more common
*NGT can be warranted if needed post-op or if it is suspected it may take several days for the bowel to wake up/heal*
187
What are the SCIP goals mentioned in lecture?
Antibiotics within 1 hour of first incision, beta blockers within 24 hours (only if the patient is taking beta blockers), keep temp above 36 C and time out prior to incision
188
List the breast surgeries from least to most invasive
Biopsy, lumpectomy/partial mastectomy, simple mastectomy, modified radical and radical mastectomy
189
What type of breast surgery involves an excision of a breast lesion with margins?
Biopsy
190
What type of breast surgery involves a partial mastectomy?
Lumpectomy
191
At what lesion size is a partial mastectomy generally indicated?
2.5 - 5.0 cm
192
What type of breast surgery involves the breast/nipple?
Simple mastectomy
*generally indicated when there is no lymph node involvement or patient is a poor surgical candidate*
193
What type of breast surgery involves the breast, nipple, axillary lymph nodes and may or may not involved reconstruction?
Modified radical mastectomy
194
What type of breast surgery involves the entire breast, lymph nodes and pectoralis muscle?
Radical mastectomy
195
Why should a thorough evaluation of CV and pulm status be done prior to cancer-related breast procedures?
Because radiation/chemo can have negative impact on both systems.
*pregnancy test is generally recommended as well*
196
What dyes can be used for SLN (sentinel lymph node) mapping?
Methylene blue (avoid in renal insufficiency)
Indigo carmine (avoid in sulfa allergy patients)
Lymphazurin (the preferred agent)
197
What breast reconstruction is done below the scapula, involves muscle/skin and cut away as a pedicle graft and tunneled through the axilla?
Latissimus dorsi myocutaneous (LDM) or Lat flap
198
What breast reconstruction is done with abdominal muscle, sub-q tissue/skin, remains attached to native blood supply with a mesh prosthesis to the abdomen?
Transverse rectus abdominus myocutaneous (TRAM) or Tram flap
199
What breast reconstruction has skin and fat removed from the abdomen (without muscle) that denervates the abdomen?
Deep inferior epigastric perforators (DIEP)
200
Primary indication for Nissen fundoplication?
To increase LES pressure related to complications from GERD
201
Pre-op steps for Nissen fundoplication?
Identify which PPI they are on, whether or not they are on prokinetics and identify if there is documented history of esophageal hypderacidity
202
Position for Nissen fundoplication?
Supine, low lithotomy or R T-burg
203
Intraoperative concerns for Nissen fundoplication?
GETA via RSI, place an OGT, ensure appropriate pre-op meds given, SCIP antibiotics and ensure esophageal dilator is available
204
What structures make up the triangle of Calot?
The cystic duct, the common hepatic duct and the inferior surface of the liver
*important because the is the safest area for the surgeon to access the gallbladder*
205
What are the 5 F's of cholecystectomy?
female, forty, fair, flatulent, fat
206
Many cholecystectomy surgeries are emergent and therefore treated as what by anesthesia?
They are treated as if they are full stomach patients. Give prokinetics, Bictira can also help
207
Positions for a cholecystectomy?
Supine, R T-burg with left tilt
208
What is IOC in a cholecystectomy?
Intraoperative cholangiography
209
IOC (Intraoperative cholangiography) may cause what as a side effect?
Sphincter of Oddi spasm - treat with glucagon
210
ERCP may be required for what condition?
Choledocholithiasis
211
Common reasons for a spleenectomy?
ITP (Immune thrombocytopenic purpura)
Lymphoma
Hemolytic anemia
Trauma
212
What steps should be taken before a spleenectomy?
Ensure the patient has had pneumococcal, meningococcal, and H influenza vaccinations 1 week preop. Evaluate for the presence of LLL atelectasis (if this is present, it is a sign that the spleen is larger than anticipated)
213
Position for a spleenectomy?
45 degree right lateral decubitus
Kidney rest, table flexed
214
Common indications for a bowel resection?
Ulcerative colitis
Crohn’s disease
Diverticular disease
Cancers
Ischemic bowel
215
What mu-opioid antagonist may be helpful in bowel surgery?
Entereg (Alvimopan)
*In order to take advantage of this drug, it MUST be given before any other narcotic is administered. If appropriately given, this drug can decreased the GI related effects of narcotics*
216
What are the ERAS (early recover after surgery) goals of bowel resesction?
Pre-op warming, multi-modal pain/PONV control (Gabapentin, acetaminophen, scopolamine) and liquid carbohydrate drinks before surgery like Gatorade can help
217
Position for bowel resesction?
Supine or low lithotomy
218
What post-operative pain intervention can be helpful with bowel resection that also can avoid narcotic usage to minimize bowel "down" time?
A lumbar epidural
219
Dehydration d/t fever and or N/V in appendicitis may result in what lab value changes?
Hemoconcentration and elevated BUN with a normal creatinine
220
Position for an appendectomy ?
Supine with left arm tucked or T-Burg
221
GETA concerns for an appendectomy?
Always consider full stomach/aspiration risk
222
What bariatric surgery has slow weight loss? Fast?
Slow = Lap banding
Fast = Sleeve and bypass
223
What bariatric surgery does not affect nutrients? Which does?
Does not = Lap banding and sleeve
Does = Bypass
224
What bariatric surgery is easily removed/reversed? Not easily removed/reversed?
Easy = Lap banding
Not easy = Sleeve and bypass
225
What bariatric surgery have suture lines?
Sleeve and bypass
226
What are the indications for bariatric surgery?
BMI greater than 40, or BMI greater than 35 with comorbidities (HTN, DM, OSA, asthma among others)
227
What pre-operative intervention, per lecture, is critically important in obese patients?
Ensure appropriate VTE prophylaxis
228
Bariatric surgery position?
R T-burg with HOB elevated 30 degrees
229
What type of induction is preferred in bariatric surgery?
GETA with RSI - obese patients do not tolerate supine position well and can easily become hypoxic
230
When should the OGT be dc'd in bariatric surgery?
Before the stomach is stapled
231
Common long term problems with bariatric surgery?
Diarrhea, dysphagia, protein malabsorption and vitamin malabsorption
232
What vitamins/minerals are bariatric surgery patients at risk of being deficient in?
A, D, E, K, B12, calcium
233
What factors can convert a minimally invasive abdominal surgery to full laparotomy?
Obesity
Adhesions
Bleeding
Unclear anatomy
Staple misfire
Inability to ventilate
234
Indications for ex-lap?
Trauma
Abdominal catastrophes
Staging (staging of cancer)
235
What are some of the primary intraoperative concerns during an ex-lap?
You need profound muscle relaxation and must keep them warm. An epidural placement may be very beneficial for pain control
236
PONV risk factors in relation to gynecological surgery?
Female, Laparoscopy vs Laparotomy, opioids and volatiles
237
What is the purpose of a D&C?
To remove the endometrial lining of the uterus. It may also diagnose/treat bleeding from uterus/cervix
238
Position for D&C?
Lithotomy
239
Intra-op concerns for a D&C?
GETA, no SCIP antibiotics, may be combined with other procedures (hysteroscopy or conization), may require Pitocin and may have bradycardia
240
What is a D & E surgery?
Dilation and evacuation - aka abortion
241
What are some of the variable factors for each state that can influence whether or not a D & E can be done?
Wait time, 20 - 24 weeks, may require counseling/waiting period and may require parental involvement.
242
Where is Pitocin secreted from?
Neuro-hypophysis
243
What other compound does Pitocin mimic?
Vasopressin (ADH) - both increase water reabsorption
244
What can you use to inflate the uterus during hysteroscopy?
NS, LRS or sorbitol
*the concern with sorbitol is it can cause sugar excess and may also cause a seizure*
245
The 2 primary anesthesia modalities for hysteroscopy?
Paracervical block or GETA
246
Position for hysteroscopy?
Lithotomy
247
What patient populations are urethral slings commonly performed on?
Older women who had numerous children or college athletes
248
What is inserted during a sling procedure?
A prolene mesh
249
Sling procedure patient position?
Lithotomy
250
Patient position for condyloma?
Lithotomy
251
What safety step must be taken for a condyloma?
Laser evacuation - so laser masks and ensure appropriate smoke evacuation
252
What are the 3 types of vaginal prolapses?
Cystocele - anterior prolapse of the bladder into the vagina
Rectocele - posterior prolapse of the rectum into the vagina
*Enterocele is also on the slide. That is a small bowel prolapse*
253
Intra-op considerations for vaginal repair procedures?
Lithotomy position, GA via ET or LMA, SCIP and a foley
254
What are some of the considerations to robotic surgery?
Allows for 3-dimensional vision, improved dexterity but increased cost and longer operating time
255
What are 3 important steps/safety measures for robotic surgery?
Keep the patient in the original position, good muscle relaxation and fluid restriction
256
What are the pressures in the high, intermediate, and low pressure systems?
High = Starts at 2200 then via the 1st stage regulator PSI drops in the intermediate system
Intermediate = 1st stage regulator drops PSI to 45, or 50 - 55 PSI in the pipeline
Low = 2nd stage regulator maintains it at 14 - 30 PSI
(pressure in the low pressure system should be slightly above atmospheric and is variable)
257
What type of anesthesia machines uses this flowmeter sequence?
Drager
258
What type of anesthesia machines uses this flowmeter sequence?
Ohmeda
259
What gases can act as driving gases for the bellows?
Air, oxygen or a mix
260
What is the purpose of the pressure-limiting mechanism?
To limit inspiratory pressure, the general set-point is 10 cm H2O above peak pressure with desired Vt
261
What breast reconstruction procedures keep the native vessels intact?
Lat flap (not on slide but mentioned in lecture) and Tram flap
262
What puts you at risk for a weakened pelvic floor?
Delivery with a postponed repair, aging or prior pelvic surgery
263
What are the 3 types of hysterectomy access?
Abdominal: via midline or Pfannenstiel incision
Vaginal
LAVH - laparoscopically assisted vaginal hysterectomy
264
What is the basic difference between a Tram flap and a Diep flap?
A tram flap involves abdominal muscle, the Diep spares the abdominal muscle
265
What is the TWA maximum concentration for halogenated agents in conjunction with other gases? When it is a halogenated agent alone?
Combined = 0.5 ppm
Halogenated agent alone = 2 ppm
266
At what point does a decrease in GFR become symptomatic?
50% decrease
267
What are the s/sx of moderate vs severe renal insufficiency?
Mod = increased Bun/Creat; anemia; decreased energy
Severe = profound uremia; acidemia; volume overload
268
Normal Bun/Cr?
Bun: 8 - 18 mg/dL
Cr: 0.8 - 1.2 mg/dL
269
What factors can elevate Bun even if the kidneys are healthy? When does kidney disease elevated Bun?
Exercise, steroids, dehydration. Bun is affected when GFR is 75% of normal or a 25% decrease in function
270
What type of anemia is generally attributed to renal dysfunction?
Normochromic (normal color) normocytic (normal size) iron deficient anemia
271
What causes HTN with renal disease?
Usually d/t the RAAS in over-drive
272
What types of drugs are metabolized in the liver? Kidneys?
Lipid soluble and non-ionized = liver
Ionized and excreted unchanged = renal
273
What drugs are listed as commonly being renally excreted?
Muscle relaxants (Pancuronium), H2 blockers, Cholinesterase inhibitors, thiazides, digoxin, many anti-biotics and drugs with metabolites (morphine/meperidine/ketamine/midazolam)
274
What conditions paired with renal disease are of particular concern in regards to surgical mortality?
Cardiac/valve surgery, sepsis, crush injuries, toxins and NSAIDs
*mortality rate can reach as high as 50%*
275
What protective steps are used for renal protection in high risk cases?
Maintain adequate fluid volume status, maintain RBF. Use of Mannitol, low-dose dopamine, fenoldopam, loop diuretics, bicarbonate drips can help maintain urine flow
276
What drug can be used to help preserve renal function if exposed to a high dose of radiopaque dye?
N-acetylcysteine
277
Indications for urological surgery?
Direct visualization of urethra, bladder, ureter and kidney
*can help with biopsies/evaluate bleeding, retrograde pyelography, laser/retrieve stones, remove/treat stricture and resect masses*
278
Common position for urologic surgery?
Lithotomy position
*watch for peroneal and femoral nerve injury. Watch fingers closely as well*
279
What is the name of the procedures that use a scope to evaluate the urethra, bladder or ureteral orifice?
Through urethra (urethroscopy)
Through bladder (cystoscopy)
Through ureteral orifice (ureteroscopy)
280
Common indications for urethroscopy/cystoscopy?
Visualize the urethra and/or bladder d/t urinary symptoms (Pain, burning, hematuria, difficult urination)
Diagnosis: lesions, strictures (Dilate stricture, treat cystitis, stent placement, resect tumors)
281
What is the procedure of choice for mid/distal ureter or bilateral stones?
Ureteroscopy
*may incorporate laser technology*
282
How likely are men/women to develop kidney stones? reoccurrence rate?
Men = 10%, women = 5%. 50% chance of stones coming back
*complication rate is low, perforation occurs 5% of the time, stricture formation less than 2%*
283
What is the MET (medical expulsion therapy) for kidney stones?
NSAIDs, aggressive fluids and calcium channel/alpha blockers
284
What are the 3 choices of surgery to address kidney stones?
Stone basket/laser, SWL (shock wave lithotripsy) or percutaneous nephrolithotomy
285
What type of stones does SWL work best on?
Best suited for small/medium intranephric stones
*there is risk of kidney injury or sub-capsular hematoma*
286
What advantages does newer SWL have over the older?
Less pain and significantly less heat loss
287
What are the absolute and relative contraindications to SWL?
Once again, I'm too lazy to type it all out
288
What are some pre-op steps to consider before SWL?
Single IV, anxiolytic, SCIP antibiotics, be aware of an iodine allergy
289
Intra-op strategy for SWL?
Can be local or GA, can be LMA vs ETT, minimal narcotics with newer SWL (almost no pain), may need an anti-emetic, eye covering for lasers and lead for providers
290
When is percutaneous nephrolithotomy generally indicated?
For large intranephric stones
*generally requires initial placement of ureteral stents and uses larger amounts of fluoroscopy. TUR syndrome a concern*
291
Pre-op and intra-op considerations for percutaneous nephrolithotomy?
Pre = single IV, anxiolytic and SCIP antibiotics
Intra = GETA, short NMBDs, lateral position, lead aprons and eye protection for lasers
292
Describe an Orchiectomy
Almost always bilateral; spermatic cord is clamped, cut, and sutured (common with metastatic prostate cancer)
293
Describe a hydrocelectomy
Wall of hydrocele excised and edges sutured to prevent recurrence
294
Describe testicular torsion
Spermatic cord becomes twisted. Considered a medical emergency. Must be performed within 6 hours to prevent irreversible ischemic damage.
295
Indications for circumcision?
Phimosis (can't retract the foreskin) and to reduce penile/prostate cancer risk
296
Describe a hypospadias repair
A surgery to correct a defect in the opening of the penis that is present at birth
297
Describe a penectomy
Removal of tissue, usually cancerous in nature and may include inguinal lymph node biopsy
*commonly a squamous cell carcinoma*
298
Common disease processes that can evetually cause indications for placement of a penile prosthesis?
DM or spinal cord injury
*per lecture, take great care to be as sterile as possible with the implant*
299
Anesthesia considerations for penile operations?
Give anxiolytics, can be GETA or LMA, supine, a penile block can be used (pudendal nerve S2 - S4), SCIP - maintain sterility and manipulation of genitals can cause bradycardia
300
What must be done after a radical cystectomy?
Either place an ileal conduit or a bladder substitution
301
What would you want to know in pre-op before a cystectomy?
Know risk factors such as CAD or pulmonary disease. Get an EKG. Are they on anti-coagulants?
302
Intra-op considerations for cystectomy?
GETA/SAB/Epidural, supine, SCIP.
Complications: blood loss up to 3L, have 2 IVs and type/crossmatch. 3rd space loss common as well as hypothermia
303
Gold standard for BPH treatment?
Medical management, TURP if MM fails
304
Most common population for TURP?
Males in 50s/60s, common comorbidities include obesity, HTN, CAD, and familial history of enlarged prostate is fairly common
305
Pre-op/intra-op considerations for a TURP?
Pre-op: manage comorbidities, anti-coagulants and ensure a large bore IV
Intra-op: General/SAB, lithotomy position, be ready to transfuse blood and watch for TUR syndrome
306
What is TUR syndrome?
Hypervolemic hyponatremia from irrigation fluid during a TURP/open resection of the prostate
307
At what sodium levels do s/sx of TUR syndrome begin to develop?
308
What are the types of irrigant used in TURP?
Saline (watch for volume overload and dispersion of current d/t the sodium)
Glycine - metabolized in liver, avoid in liver patients
Water - causes intravascular hemolysis
Sorbital - metabolized to CO2 and fructose. Can elevate BG and has seizure concerns
309
At what rates does TUR syndrome become at risk to develop?
Irrigation rates of 300 ml/min
Absorption of 20 ml/min - 200 ml/min
Greater than 2L of absorption is usually required for TUR syndrome to develop
310
What steps can you use to prevent TUR?
Limit resection to 1 hour, suspend the irrigating fluid to less than 30 cm above the table and treat hypotension from SAB with vasopressors
311
Treatment of TUR syndrome?
ABCs, terminate procedure ASAP, consider invasive lines
312
At what Na level does mild vs severe symptoms occur? Treatment of each?
Mild s/sx of Na of greater than 120, Tx = fluid restriction and loop diuretics
Severe s/sx of Na less than 120, Tx = 3% IV saline
313
What are some basic steps to use for safety during a robotic prostatectomy?
Insert an arterial line, keep a neo drip on standby/ready and limit IV fluids (they are in very steep trendelenburg)
314
Nephrectomy has a complication rate of about 20%, what are the common complications?
Peritonitis, acute renal failure, hernia, visceral injury, hemorrhage, pneumothorax
315
What are the 3 types of nephrectomy?
Simple - (irreversible non-malignant disease, trauma or congenital disease)
Radical - includes the adrenal glands, common in renal cell carcinoma
Donor
316
What conditions are commonly associated with contributing to the need for a nephrectomy?
CAD, ESRD and HTN
317
Pre-op considerations for a nephrectomy?
Anxiolytics, SCIP, type/screen or cross and 2 large bore IVs
318
Intra-op considerations for a nephrectomy?
GETA, consider arterial line and/or central line (ipsilateral side), epidural or other regional anesthesia to mitigate pain and have a variety of fluid resuscitation measures and diuretics available to keep the kidney(s) making urine (colloid, blood, rapid transfusion set up, mannitol, furosemide)
319
What kidney is prefered for transplant? Where is it inserted?
The left kidney, and inferior to the native kidneys close to the iliac vasculature
*left kidney preferred because it has more/longer vasculature to work with*
320
Why is a living kidney donor so advantageous?
It avoids the physiologic alterations from DBD or DCD, less to no waiting time and decreases ischemic time
321
What does the anesthesia for the living donor encompass?
Starts a few hours prior to the recipients surgery (left kidney preferred), aggressive isotonic hydration (10 - 20 mlg/kg/hr) low level protamine reversal (you anti-coagulate prior to removing the kidney) and diuresis with lasix or mannitol to maintain 2 ml/kg/hr of urine flow
322
What is Cushing's sign?
HTN, bradycardia and widened pulse pressure
323
What are the DBD physiologic alterations?
Neurologic instability (Cushings, ICP elevation)
CV instability - massive release of catecholamine, acute MI common and CV collapse
Pulm instability - neurogenic pulmonary edema and SIRS
Metabolic instability - dysfunction of hypothalamus/pituitary systems (thermoregulation, hormones, insulin, e-lytes and DIC are all concerns)
324
In general, what type of drugs do you want to use for a cadaver donor when managing the CV system?
Drugs with a short half life
325
In a cadaver donor with refractory bradycardia not responsive to anti-cholinergics, what would be the next DOC?
Isuprel (Isoproterenol)
326
Other than hemodynamic management, what are some management strategies for anesthesia for cadaver donors?
Fluid resuscitate, avoid glucose containing solutions, PEEP/lung protective ventilation (6-8 ml/kg of IBW, 5-10 PEEP) and steroids to attenuate immune response
327
What are the donor management goals?
Short version, is try to maintain everything as close to physiologically normal as possible
328
329
What is the ischemic time for a properly stored kidney?
48 - 72 hours (try to minimize because during ischemia the kidneys lack O2, deplete ATP/glycogen, the Na/K pump fails and intracellular Na increases causing intracellular edema)
330
What conditions are very common in a patient getting a kidney transplant?
CAD and HTN (check for an EKG and/or hearth cath), DM is also very common. If they are on HD, check for their last date of HD
331
Ideal NMBD for renal transplant?
Cisatracurium (nimbex)
*ideal because its fairly short acting and metabolized by plasma cholinesterases*
332
What is the order to anastomose the renal vessels/ureters to the recipient?
Vein -> artery -> ureter
333
What is an anti-thymocyte and what is it's role in kidney transplant?
It's an infusion of rabbit-derived antibodies against human T cells to prevent/treat acute rejection
*can cause cytokine release syndrome. No treatment, just manage symptoms of fever, chills and rigors*
334
Treatment of cytokine release syndrome related to infusion of anti-thymocytes?
Steroids (usually methylprednisolone), diphenhydramine and acetaminophen
