Principles of the Anesthesia Machine Part 2 Flashcards Preview

PMI > Principles of the Anesthesia Machine Part 2 > Flashcards

Flashcards in Principles of the Anesthesia Machine Part 2 Deck (57)
Loading flashcards...
1
Q

An anesthetist is running 6L/min Air, 3L/min N2O, and 1L/min O2. What is the FiO2?

A

22.6%

2
Q

An anesthetist is running 3L/min of air and 0.5L/min of oxygen. What is the patient’s FiO2?

A

32.3%

3
Q

What is vapor pressure?

A

the pressure a vapor exerts above the liquid in a closed container

4
Q

What is latent heat of vaporization?

A

when the liquid evaporates it loses heat (gets cold)

5
Q

What is the vaporizer dial?

A

It determines the concentration of the agent that is delivered to patient

6
Q

An anesthetist is delivering straight Air and 6% Desflurane to a patient. What is the patient’s FiO2?

A

19.74%

7
Q

An anesthetist is delivering 1L/min O2, 1L/min N2O, and 2% Sevoflurane. What is the FiO2?

A

49%

8
Q

What is variable bypass?

A

some of the FGF gases bypass the vaporizer

9
Q

What volatile agents have variable bypass?

A

Isoflurane and Sevoflurane

10
Q

What volatile agent doesn’t have variable bypass? What happens instead?

A

Desflurane; a percentage of Des joins the FGF gases

11
Q

What is special about Desfluranes vaporizer?

A

It is pressurized and heated; Des has a high vapor pressure and would lose heat and it’s ability to vaporize without this special vaporizer

12
Q

What are the volatile agent safety features?

A

1-color
2-safety interlock system (one on at a time)
3- keyed filler adapter (only can put it in correct vaporizer)

13
Q

How does the machine control pressure in vent mode?

A

The ventilator has its own APL valve, relieves pressure at the end of expiration

14
Q

What could a leak in the bellows of the ventilator lead to (2)?

A

1- higher than expected PIP

2- Higher than expected FiO2

15
Q

Would you prefer your ventilator to have descending (hanging) bellows or ascending (standing) bellows? Why?

A

Ascending bellows because you can better diagnose a leak in the bellow. (No gravity to help open it up)

16
Q

What is compliance?

A

The ability of a container to expand when pressure is added to it. (old balloon [high] vs. new balloon[low])

17
Q

What are the units of pulmonary compliance?

A

mL/cmH2O

18
Q

What is the equation for pulmonary compliance?

A

change in volume (mL)/change in pressure (cmH2O)

19
Q

What is pulmonary elastic recoil (elasticity)?

A

the ability of a container to return to the original volume after the pressure has been released

20
Q

Fill in the blank:

High compliance means _____ elasticity.

A

low

21
Q

What type of patients would have high compliance?

A

COPD patients, smokers (easy inhale, hard exhale)

22
Q

What type of patients would have low compliance?

A

acute respiratory distress syndrome (hard inhale, easy exhale)

23
Q

A patient’s pulmonary compliance is 20mL/cmH2O. They are being ventilated with positive pressure ventilation (PPV) on a ventilator with 30cm/H2O pressure. What is the patient’s tidal volume?

A

600mL

24
Q

A patient on a ventilator is receiving a tidal volume of 600 mL. The inspiratory pressure waveform is shown. What is the patient’s dynamic lung compliance in mL/cmH2O?

A

30mL/cmH2O

25
Q

What are the 5 common ventilator settings?

A
1- Tidal volume (Vt)
2- Respiratory Rate (RR)
3- Inspiratory:Expiratory Ratio (I:E)
4- Peak Inspiratory Pressure (PIP)
5- Positive End Expiratory Pressure (PEEP)
26
Q

What is a normal Vt?

A

5-10L/min

27
Q

What is a normal RR?

A

8-12

28
Q

What is a normal I:E?

A

1:2 (smokers/COPD= 1:2.5)

29
Q

What is a normal PIP?

A

35-40cm/H2O for ETT

30
Q

What is a normal PEEP?

A

~5cm/H2O (if used)

31
Q

Why use PEEP?

A

To keep a small volume in the lungs after expiration to keep alveoli open and prevent atelectasis.

32
Q

What is CPAP?

A

Continuous positive airway pressure; constant PEEP

33
Q

When do you (anesthesia) use CPAP?

A

preoxygenation for obese patients

34
Q

What are the common uses for CPAP?

A

1-sleep apnea
2-patients intubated for long periods of time
3-intubated patients getting lung surgery
4-preoxygenation for obese patients

35
Q

A patient is being ventilated with a ventilator in the operating room. The respiratory rate is 10, and the I:E ratio is 1:2. How long is each inspiration/expiration for this patient?

A

2sec inspiration; 4sec expiration

36
Q

A patient is being ventilated with a ventilator in the operating room. The respiratory rate is 6, and the I:E ratio is 1:4. How long is each inspiration/expiration for this patient?

A

Each breath is 10. 2, 8 respectively

37
Q

A patient is being ventilated with a ventilator in the operating room. The respiratory rate is 3, and the I:E ratio is 1:3. How long is each inspiration/expiration for this patient?

A

Each breath is 20. 5, 15 respectively

38
Q

A patient is being ventilated with positive pressure ventilation on the ventilator. Their respiratory rate is 8 and their minute ventilation reads 3.2L. What is their tidal volume?

A

400mL

39
Q

A 35 year old, 85kg male patient is undergoing a laparoscopic hiatal hernia repair in the operating room. They are being mechanically ventilated. The fresh gas flow and ventilator settings are as follows:
RR= 10, I:E Ratio= 1:2, FGF= 2L/min air and 1L/min O2
How much FGF is entering the circuit during each inspiration?

A

100mL

40
Q

A patient is receiving mechanical ventilation with the following parameters:
RR= 10, Vt= 300mL, I:E Ratio= 1:2
What is the inspiratory flow rate in L/min?

A

9L/min

41
Q

A patient is receiving mechanical ventilation with the following parameters:
RR: 4, Vt= 600mL, I:E Ratio= 1:2
What is the expiratory flow rate in L/min?

A

3.6 L/min

42
Q

What is the Valsalva Maneuver?

A

forced exhalation against a closed glottis

43
Q

What are the three results of a Valsalva Maneuver?

A
  • increased intrathoracic pressure
  • decreased venous return
  • decreased arterial blood pressure
44
Q

How can a patient do their own valsalva maneuver?

A

bearing down or blowing through a straw

45
Q

What is a valsalva maneuver for?

A

it is a vagal response to terminate a tachyarrhythmia known as supraventricular tachycardia (SVT)

46
Q

Under general anesthesia we can deliver a valsalva maneuver by?

A
  • close APL valve
  • deliver positive pressure via bag
  • hold pressure for several seconds at 30-40cm/H2O
47
Q

Why would we do a valsalva maneuver (3)?

A

1- treat atelectasis
2- lung leak (lung surgery)
3- dura leak (neurosurgery)

48
Q

What is volume control ventilation?

A

We set the Vt that the machine will deliver no matter what pressure (assuming no Pressure limit is set)

49
Q

Let’s say that an anesthetist sets a tidal volume of 900mL for me, and it generated a peak inspiratory pressure (PIP) of 28cm/H2O. What would you expect to happen to the peak inspiratory pressure if I were 300lbs heavier, had my abdomen insufflated with CO2 for a laparoscopic surgery, and/or was placed in the Trendelenburg position?

A

It would still deliver 900mL, but the PIP would INCREASE

50
Q

Suppose an anesthetist ventilated their previous patient with 700mL tidal volumes. The next patient is 2-years old. On this 2 year old, the anesthetist turns on the ventilator without remembering to lower the tidal volume. What’s gonna happen?

A

It would still deliver 700mL, and the kids lungs would “blow up”

51
Q

What is pressure control ventilation?

A

we set the Pinspired (pressure inspired)

52
Q

What is the advantage of pressure control ventilation?

A

You will never exceed the pressure set

53
Q

What are the disadvantages of pressure control ventilation?

A

1- don’t know immediately the Vt that will be given

2- Vt will change as things in surgery change (trendelenburg; laparoscopic)

54
Q

An anesthetist is using volume control when ventilating a patient. Vent settings are as follows:
RR= 8, Vt= 700mL, PIP= 30cm/H2O
If the anesthetist increases the respiratory rate to 12, what will happen to the patients Vt and PIP?

A

Tidal volume (Vt)? Unchanged

Peak Inspiratory Pressure (PIP)? Increase, same volume must go in over a shorter period of time; vent must push faster/harder

55
Q

An anesthetist is using pressure control when ventilating a patient. Vent settings are as follows:
RR= 8, Vt= 550mL, PIP= 25cm/H2O
If the anesthetist increases the respiratory rate to 12, what will happen to the patients Vt and PIP?

A

Tidal volume (Vt)?
Decrease, bc the ventilator has to push it in faster/harder, the PIP is reached sooner; the lungs have less time to expand
Peak Inspiratory Pressure (PIP)?
Unchanged

56
Q

An anesthetist is using volume control when ventilating a patient. Vent settings are as follows:
PIP= 25cm/H2O ,Vt= 550,I:E= 1:2
If the I:E ratio is changed to 1:3, what will happen to the patient’s Vt and PIP?

A
Tidal volume (Vt)?
Unchanged 
Peak Inspiratory Pressure (PIP)?
Increase, shorter time to deliver the Vt
57
Q

An anesthetist is using pressure control when ventilating a patient. Vent settings are as follows:
PIP= 25cm/H2O ,Vt= 550,I:E= 1:2
If the I:E ratio is changed to 1:1, what will happen to the patient’s Vt and PIP?

A
Tidal volume (Vt)?
Increase; inspiratory time is longer and more volume is able to get in 
Peak Inspiratory Pressure (PIP)?
Unchanged