Bb Machines 1

Front 1

What's unique about using sevoflurane with CO2 absorbers?

Back 1

Sevo used with dessicated CO2 absorbents (especially baralyme) can lead to spontaneous fires in the cannister

Front 2

What is the main benefit of using CaOH absorbent compared to soda lime or baralyme?

Back 2

lack of NaOH and KOH which eliminates the production of both carbon monoxide and compound A

Front 3

What is the maximum absorbent capacity of soda lime and calcium hydroxide?

Back 3

soda lime - 26L CO2/100g absorbent
CaOH -10L CO2 /100g absorbent

Front 4

What inhaled anesthetics have the greatest risk of generation of carbon monoxide from CO2 absorbent?

Back 4

Des > iso > halo = sevo

Front 5

What CO2 absorbent has the highest risk of developing carbon monoxitde?

Back 5

baralyme > sodalime

Front 6

What are the 4 types of disconnect alarms?

Back 6

1. pressure alarms - triggered if set pressure is not reached
2. volume alarms - triggered if preset volume, rate, or direction is not reached
3. CO2 alarm - most important
4. other disconnect alarms - SaO2, esophageal stethescope, and TcO2

Front 7

What is the first machine alarms to detect a circuit disconnect?

Back 7

Low pressure alarm,
-mass spectrometer is a close second

Front 8

If you're given the pressure in psi of Nitrous or oxygen e cylinder how do you determine the volume left in the cylinder?

Back 8

"Ranger Rule of 0.3"
multiple the pressure in psi by 0.3
-divide that by flow in L/min to give you amount of time left

Front 9

What is the Fail Safe system?

Back 9

- if O2 supply pressure (not flow) decreases below a preset critical value the supply of other gases are shut off and an alarm sounds;
-this does not prevent delivery of hypoxic gas mixture.
-if the machine does not have a proportioning system, a hypoxic gas mixture can be delivered

Front 10

What can cause inaccuracies in flowmeters?

Back 10

1. large temperature fluctuations;
2. barometric pressure decreases result in inaccuracies at high flows (density of gas decreases and delivered flow is greater than the flowmeter reports);
3. the greater the flow the more error in actual flow delivered;
4. float must be properly aligned, the tube needs to be straight up and down
(length of tube does not affect accuracy)

Front 11

What is the best monitor to detect a flowmeter leak?

Back 11

oxygen analyzer in inspiratory limb

Front 12

What should you do if the reverse flow indicator alarms?

Back 12

-consider spontaneous respiration;
-is it at the right location (should be on expiratory limb);
-check for nonfunctional inspiratory or expiratory valve

Front 13

What is the high pressure system and how is it checked?

Back 13

Extends from the wall to the flowmeters;
-opening and checking the pressure of O2 and N20 tanks;
-this checks from the tanks to the regulator and indirectly from the wall to the flow meters

Front 14

What is the low pressure system and how is it checked?

Back 14

Extends from the flowmeters to the patient;
- checked by occluding the circuit and beginning low gas flow
-pressure should be allowed to rise to 30 mmHg and held briefly
-small leak at about 200cc is acceptable
-detects leaks in the low pressure system = flow meters, vaporizers, common gas hose, absorbent, bag, and circuit

Front 15

What is the negative pressure check test?

Back 15

-checks for leaks between common gas outlet and regulators,
-detects smaller leaks than the low pressure check test
-machine should be turned off, flow meters should be closed, bulb placed on common gas outlet and negative pressure created by collapsing the bulb
-bulb should remain collapsed for 20 seconds
-if it does remain collapsed - no leak between the regulator, flowmeters, vaporizers, and common gas outlet
-does not test the absorbent, bag, or circuit

Front 16

When do you use high frequency ventilation?

Back 16

1. bronchopleural fistula,
2. TE fistula,
3. barotrauma,
4. bronchoscopy,
5. laryngoscopy

Front 17

How can you improve oxygenation in the setting of ARDS?

Back 17

1. increase FiO2,
2. institute PEEP,
3. institute HFV,
4. diuretics, digitalis, and afterload reduction if heart failure is present

Front 18

If a patient becomes hypotensive with institution of PEEP what should you consider?

Back 18

has the patient been adequately volume loaded

Front 19

What are physiological effects of hypoventilation/hypercarbia?

Back 19

A RIPE;
Acidosis, arrhythmias,
Right shift of oxyhemoblobin curve,
Intracerebral steal,
PA pressure increase,
Epi-norepi release

Front 20

What are the physiological effects of hyperventilation/hypocarbia?

Back 20

AVCO;
Apnea, alkalosis, airway constriction;
V/Q mismatch,
decrease CO, cerebral blood flow, coronary blood flow, ca,
oxy hgb curve shift to left

Front 21

What are the effects of oxygen toxicity?

Back 21

atelectasis, pulmonary edema, alveolar hemorrhage, thickened alveolar capillary membranes

Front 22

What is the cause of oxygen toxicity?

Back 22

1. oxygen partial pressure (>0.5atm),
2, duration of exposure (can tolerate 1atm for 24hr),
3. and inherent susceptibility

Front 23

How do Ohmeda machines regulate gas pressure?

Back 23

-1st stage pressure regulator - 2200 to 45psi for oxygen, 750 to around 26psi for nitrous
-2nd stage regulator - line pressure from 50 to 14psi
-pressure relief valve opens if pressure downstream from 2nd stage regulator > 120mm Hg

Front 24

How do Drager machines regulate gas pressure?

Back 24

-1st stage pressure regulator but not a second stage pressure regulator,
-pressure relief valve set to open if pressure downstream from 1st stream regulator exceeds 15psi

Front 25

What do you need to do when a pipeline supply source crossover has occured? Why?

Back 25

disconnect pipeline supply and then turn on backup O2 source
-Bc gas will flow from whichever source is at a higher pressure
-Pipeline is at 50 psi and tank is at 45 psi so you must disconnect completely
-manual ventilation is further recommended when pipeline oxygen is unavailable if it uses it as a driving gas to compress the bellows (exception is if piston vent)

Front 26

How does vapor pressure influence how much anesthetic gas is delivered?

Back 26

the percent of anesthetic delivered increases with increased vapor pressure

Front 27

If the machine is calibrated at sea level and we take it to higher elevation what happens to VP/BP?

Back 27

-VP remains the same,
-barometric pressure decreases so the ratio increases
-therefore, the delivered concentration is higher than indicated on the dial

Front 28

How are bellows named?

Back 28

By the direction of bellows during exhalation
-ascending bellows - go up during exhalation
-descending bellows - go down during exhalation

Front 29

Explain what happens in an ascending bellows system during inspiration.

Back 29

-Bellows are compressed during inspiration - caused by delivery of a driving gas (usually oxygen) between the bellows and housing
-the spill valve (vents excess gas to scavenging system) and exhaust valve (vents driving gas) are closed

Front 30

Explain what happens in an ascending bellows system during exhalation.

Back 30

Beginning exhalation
-both exhaled and fresh gas from the breathing circuit fill the bellows and they begin to expand
-driving gas is now displaced from the area between the housing and bellows into the atmosphere
-spill valve remains closed
End exhalation
-following full expansion, continued entry of gas into the bellows causes a pressure rise which results in the opening of the spill valve at the base of the bellows
-this enables anesthetics to be vented into the scavenging system

Front 31

What happens in the case of a major leak with ascending and descending bellows?

Back 31

-ascending bellows - usually collapse, safer
-descending bellows - will continue upward and downward movement, low pressure alarm may not be activated

Front 32

What can a hole in the bellows system result in?

Back 32

Can lead to alveolar hyperventilation and barotrauma as ventilator driving gas is forced into the circuit
-if driving gas is 100% oxygen (ohmeda), O2 analyzer value will increase
-if it is an air-oxygen mix (drager), the value will decrease

Front 33

What are the 2 formulations of carbon dioxide absorbents that are commonly available?

Back 33

1. soda lime
2. calcium hydroxide
(Baralyme is no longer made)

Front 34

Which asorbent is used more commonly?

Back 34

Soda lime bc it has a greater absorptive capacity

Front 35

What is the content of soda lime?

Back 35

80% calcium hydroxide
15% water
4% sodium hydroxide
1% potassium hydroxide
small amount of silica

Front 36

What is the content of baralyme?

Back 36

20% barium hydroxide
80% calcium hydroxide
small amount of water
small amount of potassium hydroxide
no silica

Front 37

What is the newest commercially available? What is the content?

Back 37

Calcium hydroxide
-Calcium hydroxide
-calcium chloride
-calcium sulfate
-polyvinylpyrrolidine

Front 38

What factors lead to the production of compound A?

Back 38

1. use with soda lime
2. low flow or closed circuits
3. high concentrations of sevo
4. high absorbent temp
5. fresh absorbent

Front 39

What are the disadvantages of CaOH?

Back 39

1. less absorptive capacity
2. higher cost
3. less efficient

Front 40

Describe the soda lime equation.

Back 40

CO2 + water = H2CO3
H2CO3 + 2NaOH = Na2CO3 + 2 water + heat
Na2CO3 + Ca(OH)2 = CaCO3 + 2NaOH

-CO2 enters sodia ime and reacts with water to form carbonic acid
-carbonic acid then reacts with hydroxides of barium, Ca, K,, or Na to form water, heat, and carbonate of barium, Ca, K, or Na
-If heat in the cannister does not form, neutralization of CO2 may not be occurring and perhaps rebreathing is taking place
-carbonates of Ba, Ca, K, or Na react with CaOH to form Ca carbonate and hydroxides of Ba, ca, K, or Na

Front 41

Why is water necessary in absorbent?

Back 41

To dissipate heat and humidify gases

Front 42

How big must the absent cannister be?

Back 42

Greater than or equal to pt tidal volume to prevent rebreathing, irrespective of granule size

Front 43

What are the factors influencing the magnitude of carbon monoxide production from volatile anesthetics?

Back 43

1. inhaled anesthetic used
2. dryness of absorbent- completely dry > hydrated absorbent
3. high temp of absorbent - occurs during low flows
4. type of absorbent
5. higher anesthetic concentrations

Front 44

What steps can be taken to decrease carbon monoxide exposure in pts undergoing GA?

Back 44

1. turn off anesthesia machines following the last case of the day to eliminate drying of absorbents from fresh gas flow
2. add water to CO2 absorbents to rehydrate dessicated absorbent
3. use CaOH lime that is free of Na and K hydroxides

Front 45

If a circuit disconnect is proximal to the mass spectrometer sampling port what will happen? What if it is distal?

Back 45

-proximal - gases may be detected in the expiratory phase after the disconnect, with failure of the alarm to detect the problem for 15-30 seconds
-distal - inspiratory gases may be detected

Front 46

What does the oxygen fail safe detect?

Back 46

Decreased oxygen pressure into the maching and shuts off the inflow of other gases until O2 supply is reestablished

Front 47

What is the pressure and capacity of a full oxygen E cylinder?

Back 47

capacity - 625 L
pressure - 2200 psi

Front 48

What is the pressure and capacity of a full nitrous oxide E cylinder?

Back 48

capacity - 1590 L
pressure - 745 psi

Front 49

What is the pressure and capacity of a full CO2 E cylinder?

Back 49

capacity - 1590 L
pressure - 845 psi

Front 50

What is the pressure and capacity of a full air E cylinder?

Back 50

capacity - 625 L
pressure - 1800 psi

Front 51

1 atm = ____ torr = _____ psi

Back 51

760 torr = 14.7 psi

Front 52

What is the critical temp? What is it for the following: O2, N2O, CO2, and air?

Back 52

The temp above which a substance cannot be liquified regardless of the pressure placed upon it.
O2 - -120
N2O - 36 (liquid at room temp)
CO2 - 31 (liquid at room temp)
Air - -140