Anesthesia Machine

Front 1

How do you calibrate and O2 analyzer?

Back 1

1) Galvanic sensor (plug in) - expose to room air (time to 90% response is 15-20 sec, so if it takes longer than 40-60 sec to read 21%, change the sensor.). Then expose to 100%.
2) paramagnetic - internal calibration (change every 3-6 mo)

Front 2

What can you do to fix an O2 sensor that is reading an FiO2 of 0.16 (and declining) during an general anesthetic?

Back 2

Don't attempt to fix it. You must trust your monitors until you can prove it is wrong.
(Check breath sounds - midaxillary)

1. Call for help
2. Turn on E cylinder and disconnect pipeline supply from wall
3. If inspired O2 concentration doesnt increase (with adequate FGF), manually ventilate the lungs with an ambu bag and room air
4. start CPR early

Front 3

What is the normal working pressure in the anesthesia gas machine and cylinders?

Back 3

Pipeline supply is 50 psi
Cylinder pressure 2000 psi, regulated to 45 psi after it enters the machine.
Nitrous oxide cylinder pressure 745 psi when full
Air cylinder similar to O2

Front 4

Can you give an anesthetic when there is no connection for hoses? Or if a cylinder is mising?

Back 4

The hanger yoke: orients cylinders, provides unidirectional flow, and ensures a gas-tight seal. The check valve in the cylinder yoke functions to: minimize trans-filling, allow change of cylinders during use, and minimize leaks to atmosphere if a yoke is empty

There is a check valve in each pipeline inlet as well. So you can give an anesthetic even when there is no connection to the hospital pipeline or if a tank is missing.

Front 5

What is the first device that will inform you of a crossover (non-oxygen gas in the oxygen pipeline)? Is it the fail-safe? The hypoxic guard?

Back 5

Fail-safe: guards against decreased O2 pressure and not against crossover or mislabeled contents. As long as there is any pressure in the O2 line, N2O will flow. If O2 pressure is lost, the fail safe valve shuts off flow to all the other gases.

The hypoxic guard: controlls ratio of O2 and N2O so that there is a minimum of 25% O2. It does not analyze what is in the pipeline.

The first device to inform you of a crossover likely will be the oxygen analyzer. 2nd device : pulse oximeter

Front 6

For suspected crossover, what 2 actions must be taken?

Back 6

1. Turn on E cylinder
2. Then disconnect O2 pipeline supply from wall.

Front 7

What should you do if you lose O2 pipeline pressure?

Back 7

Same as crossover

Front 8

The pipeline supply of O2 has failed. How can you make your E tank supply last as long as possible?

Back 8

Driving a vent with cylinders will cause their rapid depletion. So manually ventilate the patient, assist spontaneous ventilation if possible, use air or nitrous with O2 if possible, and use low flows

Front 9

Your pipeline supply fails, and your cylinder gauge shows 1000 psi. How long will your E tank last?

Back 9

Contents L/ Gauge P = Capacity L / Service P

Full tank 660L/ 1900 psi

Front 10

What are the only 2 circumstances when a cylinder valve should be open?

Back 10

1. checking the pressure
2. when the pipeline is unavailable

Pipeline pressure may drop to less than 45 psi with flushing or vent use and some O2 from E cylinder may leak.

Front 11

What circumstances can permit a hypoxic mixture even when the hypoxic guard system is employed?

Back 11

1. Wrong supply gas in O2 pipeline or cylinder
2. Defective pneumatics or mechanics
3. Leaks downstream of flowmeter control valves
4. Inert gas administration

It is possibel to create a hypoxic mixture with air and DES

Front 12

The patients breaths are stacking up in the chest and the circuit pressure is sustained at a high level. What can you do in the few seconds before the patient is injured?

Back 12

Obstruction of the scavenger, or failure of the ventilator relief valve, may cause transmission of excess positive pressure to the pt. If suspicious, disconnect the gas collection tubing from the back of the APL valve, or turn off vacuum at the savenger interface. A scavenger interface positive pressure relief valve can create this situation. The negative pressure relief valve can also lead to accumulation of positive pressure in the chest. If you can disconnect the gas collection tubing, ventilate manually. Of the ventilator relief valve is at fault, this should be successful. If manual ventilation fails, disconnect the pt from the breathing circuit and ventilate by ambu bag.

Front 13

What is the most common site of disconnection? What is the most important monitor for disconnection?

Back 13

The most common site is the Y piece. Monitors for disconnection (apnea alarms) can be based on gas flow, circuit pressure, chemistry, or acoustic. The most important is the precordial stethoscope. Capnography is thought to be more important by some.

Front 14

What can you do to protect the patient, the next patient, and yourself when caring for an infected or immunocompromised patient?

Back 14

Cleaning the bellows is necessary after providing anesthesia to a pt with diseases transmitted by oral secretions - so with AIDS or respiratory dz:
1. dont use the ventilator
2. use bacterial filters at the Y or on each limb, use disposable soda lime assembly or change soda lime after each case.

Front 15

Name a major barotrauma risk factor which you can control.

Back 15

Oxygen flush during tthe ventilator inspiratory phase may cause barotrauma, since excess volume cannot be vented

Front 16

What is the preferred bellows design, ascending or descending?

Back 16

Ascending.
The disadvantage of the descending bellows is unrecognized disconnection (they may fill even when disconnected from the pt) and also collection of exhaled humidity in bellows

To tell: look at bellows during expiration. (Only drager Julian has hanging or descending bellows

Front 17

What is the best way to initiate mechanical ventilation so you dont forget steps?

Back 17

1. Bag/vent switch to vent
2. Turn ventilator switch on, and review mode, volume or pressure and rate settings
3. check for chest expansion with the first breathing cycles

Front 18

You have an emergency, life-threatening situation and you have not checked the machine, nor do you have time to do so. What must be checked even when time is at a premium?

Back 18

1. High pressure test of the breathing circuit.
2. When placing the mask on the patients face to pre-oxygenate them, always observe or palpate the breathing bag for fluctuation.
3. Check your suction

Front 19

What is the best way to preoxygenate?

Back 19

FGF 4-6 L/min
APL valve open
Ensure tight mask fit
3-5 min TV or 4-8 VC breaths

Tight mask is the most significant factor

Front 20

In the middle of a case your soda lime is exhausted, should you change it?

Back 20

No. Increase FGF to 5-8 L/min. May do away with need for soda lime as this is essentially non-rebreathing

Front 21

How can you tell if your patient is in respiratory acidosis from rebreathing CO2?

Back 21

Failure of inspiratory or expiratory unidirectional valves and problems with CO2 absorbent granules are the principle causes of rebreathing. While most instances should be detected by noting the increase in inspired CO2 on the capnograph, it is still worthwhile to periodically review the clinical signs of respiratory acidosis:

Rise (and later fall) in HR and BP
Hyperpnea
SNS activation - flushed, arrythmic, sweating
Increased bleeding at surgical site

Front 22

How should a scavenging interface be set?

Back 22

Keep float between the lines, and remember that the audible suction sound is and indication that it is functioning properly.

Front 23

You can smell isoflurane during a case. What should you do?

Back 23

The threshold for smelling a gas is between 5-300 ppm (NIOSH standart <2 ppm)

poor mask fit
using unscavenged technique like insufflation
flow from breathing system into room air
anestheics exhaled into the room at the end of case
spilled liquid agent
uncuffed tracheal tube, leaks around LMA cuff
machine not checked regularly for leaks

Reasons related to scavenger:
open interface with no suction on
closed interface without enough suction
obstructed gas disposal tubing

Front 24

If your FGF is 4 L/min, what volume is passing through the scavenger each minute?

Back 24

4 L/ min are exiting, otherwise you get barotrauma

Front 25

The FGF must be decreased to not more than 2 L/min immediately after tracheal intubation when using Desflurane, because be agent requires low flows. Correct?

Back 25

Only if you have a prolonged period to induce while waiting from surgery to commence and the risk of awareness does not bother you.

Front 26

How much liquid agent does a variable-bypass vaporizer use per hour?

Back 26

3 x FGF (L/min) x volume% = mL/hour

Front 27

To properly fill a vaporizer, should hold the bottle until it stops bubbling?

Back 27

No. YOu can over fill, Fill to top etched line

Front 28

What is the checkout procedure for the Tec6 desflurane vaporizer?

Back 28

1. Press and hold the mute button until all the lights and alarms activate
2. Turn on to atleast 1% and unplug the electrical outlet. A "no output" alarm should ring within seconds.

Front 29

Why is it so important to check that the vaporizers are filled before a case? If you run out you can always refill them during the case right?

Back 29

True, if your recognize they are empty

Front 30

What are the hazards of contemporary vaporizers?

Back 30

Incorrect agent
Overfilling
Tipping

If tipped more than 45 degrees from vertical liquid agent can obstruct the outflow.

Front 31

What do you do to the machine if a patient gives a history of MH?

Back 31

1. Remove or atleast drain all vaporizers and tape over the dial.
2. Change all breathing circuit disposable and soda lime
3. Flush with high FGF for at least 10 min
4. Monitor pETCO2 and core temp
5. Avoid triggers
6. Use Roc