Exam 1 Flashcards
What is the purpose of the fail-safe valve? What triggers the fail-safe valve on the anesthesia machine?
To ensure that whenever oxygen pressure is reduced and until flow ceases the set oxygen concentration will not decrease in the common gas outlet. The loss of oxygen pressure triggers the high-priority alarm audible and visible (around 30 psi)
Can a hypoxic mixture be delivered from the anesthesia machine with an intact fail-safe valve? Explain.
Yes as long as there is pressure in the oxygen line nothing in the fail-safe system prevents you from turning on a mixture of 100% nitrous oxide.
Someone could have mixed up the tanks that supply the hospital lines
How are oxygen, nitrous oxide, and air gases that are used in anesthesia typically delivered to the anesthesia machine? At what pressure must these gases be delivered for proper function of the anesthesia machine?
Typically delivered via pipeline system or gas cylinders. Oxygen at 45 psi, nitrous oxide at 45 psi
How is the delivery of erroneous gases to the anesthesia machine minimized?
Diameter Index Safety System (DISS). Safety system on pipeline systems to prevent improper connection of supply hoses. (does not prevent hypoxic gas mixture to patient)
What is the purpose of the cylinders of oxygen and nitrous oxide that are found on the back of the anesthesia machine?
In case of a pipeline failure
How is an erroneous hookup of a gas cylinder to the anesthesia machine minimized?
Pin index safety system PISS
What are the PISS numbers for Oxygen?
2,5
What are the PISS numbers for Nitrous?
3,5
How many liters are in a full oxygen tank?
660 L
What is the PSI of a full oxygen tank?
1900 psi
How many liters are in a full nitrous tank?
1590 L
What is the PSI of a full nitrous tank?
745 psi
How is the pressure of oxygen related to the volume of oxygen in an oxygen gas cylinder?
Pressure drops as oxygen volume drops
How is the pressure of nitrous oxide related to the volume of nitrous oxide in a nitrous oxide gas cylinder?
Pressure is 745 psig until about 400 L remaining, nitrous oxide is a liquified gas so pressure depends on the liquid’s vapor pressure and does not indicate the amount of gas remaining ONCE PRESSURE DROPS UNDER 745 psi REPLACE THE TANK
Why does atmospheric water vapor accumulate as frost on the outside surface of oxygen tanks and nitrous oxide tanks in use?
The can gets cold when sudden release of gas as pressure decreases. It tries to gain energy back from the environment to heat back up. Potential to cause frostbite. (more likely to occur in humid locations) Joule Thomson Effect
What is the purpose of flowmeters on an anesthesia machine?
To show the flow rate of gas being administered; precisely controls and measures gas flow to common gas outlet
Are flowmeters for various gases interchangeable?
No. specifically designed and calibrated for each gas
Why is the oxygen flowmeter the last flowmeter in a series on the anesthesia machine with respect to the direction in which the gas flows?
To prevent a hypoxic mixture, oxygen is the last gas to leave the machine and is closest to the common gas outlet. All gasses flow to the right; oxygen is furthest on the right.
What is the purpose of the oxygen flush valve?
A straight shot of oxygen from the common gas outlet bypassing vaporizers and flowmeters
What is the flow of oxygen delivered to the patient when the oxygen flush valve is depressed?
35 – 75 L/min
What is the risk of activating the oxygen flush valve during a mechanically delivered inspiration?
Barotrauma/ pneumothorax
Why do volatile anesthetics require placement in a vaporizer for their inhaled delivery to patients via the anesthesia machine?
To convert them from liquid to vapor.
What is the heat of vaporization?
The number of calories required at a specific temperature to convert 1 Gram of liquid to a vapor
What influence does temperature have on vapor pressure?
As temperature increases, more molecules enter vapor phase and vapor pressure increases
Why are contemporary vaporizers unsuitable for use with desflurane?
Desflurane has a high vapor pressure
Describe how contemporary vaporizers for volatile anesthetics are classified.
Based on their vapor pressure (high vapor pressure or lower vapor pressure)
What does the term agent-specific refer to?
Agent = Volatile anesthetic gas. Each vaporizer is pressure/temperature calibrated for that specific agent.
How does tipping of a vaporizer affect vaporizer output?
Excessive tipping can cause the liquid agent to enter the bypass chamber and can cause an output with extremely high agent vapor concentration
How is the delivery of two different volatile anesthetics to the same patient via the same anesthesia machine prevented?
Vaporizer Interlock Mechanism
What is the function of anesthetic breathing systems?
Deliver oxygen and anesthetic mixture to the patient and eliminate CO2 from the breathing circuit
How do anesthetic breathing systems impart resistance to the spontaneously ventilating patient?
Small diameter or long circuits, small ET tubes, LMAs, HMEs, unidirectional valves can all create resistance. Controlled vent modes when pt is trying to breathe can also increase resistance
What classifies an anesthesia breathing system as open?
No reservoir, no rebreathing
What classifies an anesthesia breathing system as semi-open?
Reservoir, no rebreathing
What classifies an anesthesia breathing system as semi-closed?
Reservoir, partial rebreathing
What classifies an anesthesia breathing system as closed?
Reservoir, complete rebreathing
What are the most commonly used anesthetic breathing systems?
Circle breathing systems
How does the circle system prevent rebreathing of carbon dioxide?
Unidirectional valves and CO2 absorbents
What is the most commonly used circle breathing system used in the United States?
Semiclosed system
What are some advantages of the semi-closed and closed circle systems?
They conserve heat and moisture efficiently. Economic use of anesthetic gases. Minimizes release of anesthetic gases into environment.
What are some disadvantages of the circle anesthetic breathing system?
Complex design (10+ different connections). Malfunction of unidirectional valves can result in life-threatening problems. Rebreathing, total occlusion of circuit if stuck shut.
What is the impact of the rebreathing of anesthetic gases in a semi-closed circle system?
Minimizes environmental impact of anesthetic gases on environment
What does dead space mean? Where is the dead space in the circle system?
Ventilation of structures that do not participate in gas exchange.
From the y piece to the patients lungs, including ETT, connectors, and valves.
What is advantageous about the corrugated tubing in the circle system?
Prevents kinking of the tube. Is sturdy but flexible
What are other names for the adjustable pressure-limiting (APL) valve?
Pop-off valve or adjustable pressure relief valve
What are the advantages of the reservoir bag on the circle system?
Prevents retrograde flow through the system
what is the vulnerable area of the anesthesia workstation and why?
the low-pressure circuit, it is most subject to breaks and leaks
where is the low pressure circuit located?
downstream from all anesthesia machine safety features except the oxygen analyzer (or, in some cases, the ratio controller), and it is the portion of the machine where a leak is most likely to go unrecognized if an inappropriate LPC leak test is performed
what should be checked for leaks before administering an anesthetic
the circle breathing system
when can internal vaporizer leaks be detected?
when the vaporizer is turned to the “on” position
what are the oxygen failure cutoff valves?
they help minimize the likelihood of delivery of a hypoxic gas mizture
when can Compound A be formed and why?
during sevoflurane anesthesia; inhaled anesthetics can interact with CO2 absorbents
what is the most common cylinder used in anesthesia?
E-cylinder
what are examples of non-liquefied gases?
oxygen, nitrogen, air, helium
what does a 3AA tank marking indicate?
steel
what does a 3AL tank marking indicate?
aluminum, MRI compatible
what temperature could cause a cylinder to explode?
> 57º C (~134º F)
what gas law applies to the function of the pressure relief valve?
Gay-Lussac’s law
increasing temperature = increasing pressure
what is the only true way to know how much N2O is in a tank?
weighing the tank
how should N2O be stored?
critical temp= 36º C (right above room temp)
what kind of thermal injury may arise from a N2O tank?
cold burn
what is the Joule Thomson effect?
cooling or freezing on the surface of a cylinder
what is the only monitor to detect low O2 concentrations?
the oxygen monitor on the machine; it is a high alert alarm
what part of the anesthesia machine drops the pressure to an operable level? what does it drop the PSI to?
the second-stage pressure regulator; 16 PSI
when does the oxygen failure safety valve shut off the flow of all other gases?
when the oxygen falls below the set limit, usually 20-25 PSI
how is the oxygen flow valve different from the others?
it is fluted, larger than other, protrudes further out
where does the low-pressure system begin?
at the second stage regulator
what is the PSI reduced to at the second stage regulator?
~16 PSI
how are the changes of a hypoxic mixture of gas minimized in the event of a gas leak?
oxygen is the furthest to the right so it is always delivered
what is a volatile agent?
an anesthetic agent which exists as a liquid at room temperature and evaporates easily for administration by inhalation
what does the bag/vent switch do?
it allows the user to either manually ventilate the patient, or utilize the mechanical ventilator
what happens if the APL valve is open too wide?
too much volume is allowed to escape and not enough is delivered to the patient
what are the final products of CO2 neutralization?
carbonates, water, and heat
when should the carbon dioxide absorbent canister be replaced?
when 50-70% of the granules have turned purple
define tidal volume
volume of gas entering or leaving the patient during the inspiratory or expiratory phase time
define minute volume
sum of the tidal volumes in one minute
define ventilatory frequency
number of respiratory cycles per minute
define I:E ratio
the ratio of inspiratory phase time to expiratory phase time
what is a typical I:E?
1:2
what tidal volume is usually used to ventilate patients?
5-8 mL/kg of ideal body weight
goal ETCO2?
35-45 mmHg
what % FiO2 is generally used through the case?
50-60%
what % FiO2 should be used during induction and emergence?
100%
what kind of airway is generally used in pressure-cycled mode?
LMAs
when should a complete anesthesia machine checkout be completed?
every morning prior to the first case
At what temperature is the operating room usually maintained?
Usually between 68 to 73º F
What are the risks of hypothermia in the patient?
Wound infection, increased intraoperative blood loss, impaired coagulation
What occurs if the humidity in the OR is kept too low or high?
-If humidity is too high; damp or moist supplies, and therefore an increased risk of contamination
-If humidity is too low it facilitates airborne motility of particulate matter, vector for infection, increases incidence of static changes
How many air exchanges occur per hour in the operating room?
25
What is the maximum published criteria for anesthetic waste exposure? (parts per million)
25 ppm N2O
2ppm for halogenated agents
0.5ppm for halogenated agents/25ppm N2O when used in combination
What effects do the anesthetic gases have on the health care worker?
Can cause headaches, nausea and vomiting, and congenital defects in the provider
How does methyl methacrylate affect the patient?
Known cardiovascular complications of methyl methacrylate in surgical patients include hypotension, bradycardia, and cardiac arrest.
Reported risks from repeated occupational exposure to methyl methacrylate include skin irritation and burns, systemic allergic reactions, eye irritation, headache, neurologic signs, adverse reproductive outcomes, and organ damage.
What is the surgical care improvement project?
Preop antibiotic within one hour before incision (2 hours for Vancomycin and Fluoroquinolones)
Proper hair removal method with the use of clippers
Blood glucose < 200 mg/dL
Maintain normothermia > 36C
What are the OSHA occupational limits on radiation exposure?
The annual limit is 5 rem
Pregnant: 0.5mrem per month for a total exposure of 5mrem
Describe the fire triad?
Heat, fuel, and oxygen are required to keep the fire burning
How can you prevent an OF fire?
Wet gauze around the area
Turn down the O2 for 2-3 min before the surgeon needs cautery
Let alcohol-based solutions dry first
FiO2 less than 30%
What should you do if there is an airway fire?
Remove the tracheal tube, stop the flow of all airway gases, remove flammable material from the airway, and pour saline into the airway. Inspect the airway and reintubate
What kind of fire extinguisher for a fire in the OR?
CO2 extinguisher
What should you do if there is fire on the patient?
Extinguish the fire with a basin or saline of the most rapid and effective method.
Remove burning drapes and place them on the floor.
Paper drapes are impermeable to water
Extinguish the fire with a fire extinguisher.
How do you treat opioid-induced biliary spasms?
Naloxone or glucagon to relax the sphincter muscle
Which opioid should not be used in patients taking MAOI?
Meperidine (demerol) because it can lead to serotonin syndrome
How is morphine metabolized?
Rapid metabolism by UGT2B7 in the liver.
Within minutes after admin, hydrophilic metabolites are present in plasma. 60% converts to morphine-3-glucuronide (MG3) and 5-10% to morphine-6-glucuronide (M6G)(active). Slow limited crossover to bbb.
How remifentanil metabolized?
Rapidly metabolized by non-specific blood and tissue esterases. Half life is about 3-10 mins.
What are the most prominent CNS effects of opioids?
Analgesia, sedation, respiratory depression, hypotension, bradycardia
How do opioids affect the CO2 response curve?
Decrease in slope and shift to the right
What are the side effects of naloxone administration?
Pain and catecholamine-associated hypertension and cardiac ischemia if not monitored properly.
The incidence of “re-narcotization” is high with opioids with a longer plasma half-life because the rate of decay in the plasma of naloxone is short
Which morphine metabolite is active?
morphine-6-glucuronide
How do opioids affect cerebral blood flow?
Reduce CBF, usually proportional to the decrease in CMRO2. (brain blood flow is based on metabolic needs)
Which opioid releases histamine?
morphine
What are the cardiovascular effects of opioids?
bradycardia, hypotension
What are the respiratory effects of opioids?
it can cause life-threatening respiratory depression
What are the mechanisms of opioid-induced hypotension?
Depression of vasomotor centers in the brainstem, causing vasodilation
Which opioid is cardiac depressant and increases heart rate?
morphine
What are the effects of opioids on cerebral metabolic rate?
Decreased cerebral metabolic rate, reducing the brains consumption of oxygen.
Which opioid is effective in treating shivering?
meperidine (demerol)
do opioids cross the placenta?
yes drugs with low MW diffuse freely
which drugs do not cross the placenta
Heparin, Insulin, Glycopyrrolate, NDNMB, Succinylcholine
How do opioids affect the respiratory pattern?
they decrease RR and increase TV
What is the mechanism of opioid-induced bradycardia?
Activation of the vagal nuclei in the brain stem
Extrinsic muscles of the larynx
move the larynx as a whole
intrinsic muscles of the larynx
move the various cartilages in relation to one another
which branches of the larynx innervate the hypopharynx?
Superior laryngeal nerve & Recurrent laryngeal nerve.
Recurrent laryngeal nerve supplies all of intrinsic muscles of the larynx (except the cricothyroid)
What does the superior laryngeal nerve innervate in the larynx?
Provides sensory innervation from the level of the vocal cords to the underside of the epiglottis
What does the recurrent laryngeal nerve innervate in the larynx?
Recurrent laryngeal nerve innervates the supply of all the intrinsic muscles of the larynx except the cricothyroid
Trauma to the RLN can result in Vocal Cord Dysfunction
What is the sensory innervation in the gag reflex?
cranial nerve IX; the glossopharyngeal nerve
What are the characteristics associated with a difficult intubation?
Small mouth opening, long incisors, prominent overbite, high arched palate, Mallampati 3 or 4, retrognathic jaw, inability to sublux jaw, short-thick neck, short thyro-mental distance, and reduced cervical mobility
What is the sniffing position?
Sniffing position includes cervical flexion, atlanto-occipital extension, It brings the oral, pharyngeal, and laryngeal axes into alignment during laryngoscopy.
Class 1 Mallampati
pillars, uvula, soft and hard palate
Class 2 Mallampati
pillars,
uvula and soft palate
Class 3 Mallampati
Soft palate and hard palate visible
Class 4 Mallampati
Only hard palate visible
is a higher or lower mallampati score associated with a more difficult intubation?
higher score (3-4)
what is the Sellicks maneuver?
cricoid pressure
how much pressure is used to ventilate the patient?
no more than 20-25 cm H2O
how do you measure an appropriately sized oral airway?
Measure the corner of the mouth to the earlobe or the angle of the mandible
The flange should protrude outside of the lips and the pharyngeal end should rest at the base of the tongue
complications of OPA
vomiting, dental injury, oropharyngeal trauma, ischemia
how do you measure an appropriately sized nasal airway?
Measure from the nare to the earlobe or angle of mandible
what is the appropriate sized ETT for a female?
6.0-7.0
what is the appropriate sized ETT for a male?
7.0-8.0
what is the appropriate depth of insertion for an ETT?
21 to 23 cm
how do you confirm ETT placement in the trachea?
- Visualization of placement through cords
- End tidal CO2 with capnography
- Bilateral breath sounds on auscultation
- Visualization of chest excursion
- Condensation in the endotracheal tube
what is the maximum pressure that you can ventilate with while using an LMA?
20 cm of H2O pressure
what are the criteria for extubating in a patient after general anesthesia?
- Return of consciousness
- Spontaneous respirations
- Resolution of neuromuscular blockade (sustained tetany at least 5 seconds
- Ability to follow commands
- Sustained head life for 5 seconds
- Sustained hand grasp
- Spontaneous tidal volume >6 cc/kg
- Negative inspiratory pressure >20 cm H2O
what is a normal inter-incisor gap?
2-3 fingers, or 4 cm
To expose the glottic opening during laryngoscopy, you must displace the tongue into
the
submandibular space
a TMD less than ______ cm or greater than ______ cm correlated with an increased risk of difficult intubation
6 cm; 9 cm
the mandibular protrusion test (MPT) assesses the function of?
the TMJ
the ability to place the patient into the sniffing position is highly dependent on the mobility of what joint?
the atlanto-occipital
what grading system helps ups measure the laryngoscopic view we obtain during direct laryngoscopy?
the Cormack & Lehane Score
list some risk factors for mask ventilation
B.O.N.E.S
beard
obese
no teeth
elderly
snoring
what are some risk factors for a difficult supraglottic airway?
RODS
Restricted mouth opening
obstruction
distorted airway
stiff lungs & c-spine
2 hour fasting recommendation for healthy patients
clear liquids
4 hour fasting recommendation for healthy patients
breast milk
6 hour fasting recommendation for healthy patients
non human milk, infant formula, solid food
8 hour fasting recommendation for healthy patients
fried or fatty foods
ingestion of clear liquids ______ hours before surgery reduces __________ and increases ________
ingestion of clear liquids 2 hours before surgery reduces gastric volume and increases gastric pH
risk factors for Medelson syndrom
gastric pH less than 2.5; gastric volume greater than 25 mL
how do you apply cricoid pressure?
pressure is applied to the cricoid ring against the C5 vertebra before the patient loses consciousness & maintained until tracheal intubation is confirmed
upper airway obstruction is the chief concern in the patient with
angioedema
angioedema caused by anaphylaxis is best treated with:
epi, antihistamines, & steroids
Ludwig’s angina is
a bacterial infection characterized by rapidly progressing cellulitis in the floor of the mouth
what is the most significant concern in a patient with Ludwig’s angina?
posterior placement of the tongue resulting in complete supraglottic airway obstructiont
the best method of securing the airway in a patient with Ludwig’s angina
is awake nasal intubation and awake tracheostomy
list congenital conditions that manifest with a large tongue
Big Tongue
Beckwith Syndrome & Trisomy 21
list congenital conditions that manifest with small/underdeveloped mandible
Please Get That Chin
Pierre Robin
Goldenhar
Treacher Collins
Cri du Chat
list congenital conditions that manifest with cervical spine anomalies
Kids Try Gold
Klippel-Feil
Trisomy 21
Goldenhar
the sniffing position includes
cervical flexion & atlanto-occipital extension
what does nose to chest position do the to ETT?
pushes the tip of the ETT towards the carina ~2cm
what does nose away from chest position do the to ETT?
pulls the tip of the ETT away from the carina ~2cm
what does lateral rotation of the head do to the ETT?
moves the tip of the ETT away from the carina ~0.7cm
which nerve is most likely to be injured by an aggressive jaw thrust?
the facial nerve
Which nerve is most likely to be injured by a face mask strap that is too tight? How will the patient present?
the buccal branch of the facial nerve (CNVII)
pt will have difficulty opening and closing lips
what are complications of an OPA?
vomiting, dental injury, oropharyngeal trauma, ischemia
what are complications of an NPA?
bleeding
what is a contraindications to an NPA?
cribriform plate injury –> risk of brain injury
when using an ETT, the cuff pressure should be less than _____ cm H2O?
25 cm H2O
what is the purpose of Murphy’s Eye?
a small hole on the opposite side of the bevel to provide an alternate passage for air movement in case the tip of the ETT becomes occluded or up against the tracheal wall
ETT size without a cuff formula
(age/4) + 4
ETT size with a cuff formula
(age/4) + 3.5
if you can’t get a good seal w the LMA consider…
adding air to the cuff
two other names for the intubating stylet are:
Eschman & Bougie
retrograde intubation
a blind procedure where tracheal intubation is accomplished by passing the ETT over a wire
extubation should be performed when the patient is
deep or awake, not in between
puncturing the cricothyroid membrane during retrograde intubation should be done with what size needle?
14 to 18 gauge
what PSI does transtracheal jet ventilation require?
~ 50 psi
