Ch. 6 Test, Initial Vent Settings

Question 1

Calculate the average tidal volume for a patient who has a minute ventilation of 10 L/min with a respiratory rate (RR) of 12 bpm.

a. 120 mL
b. 833 mL
c. 1000 mL
d. 1200 mL

Answer 1

ANS: B
Minute ventilation equals respiratory rate multiplied by tidal volume (VT). Therefore, tidal volume equals minute ventilation divided by respiratory rate.

DIF: 2 REF: pg. 87

Question 2

Calculate the inspiratory time (TI) when a ventilator is set at a tidal volume (VT) of 800 mL and a constant flow rate of 40 L/min.

a. 0.02 second
b. 0.5 second
c. 1.2 seconds
d. 3.2 seconds

Answer 2

ANS:	C
Inspiratory Time (TI) = Tidal Volume (VT)/Minute Ventilation (VE) (convert L/min to L/sec first)

DIF: 2 REF: pgs. 89. 90

Question 3

Calculate the inspiratory time (TI) when a ventilator is set at a tidal volume (VT) of 500 mL and a constant flow rate of 30 L/min.

a. 0.6 second
b. 1 second
c. 1.5 seconds
d. 1.7 seconds

Answer 3

ANS:	B
Inspiratory Time (TI) = Tidal Volume (VT)/Minute Ventilation (VE) (convert L/min to L/sec first)

DIF: 2 REF: pgs. 89, 90

Question 4

Calculate the inspiratory to expiratory (I:E) ratio for a ventilator that is set to deliver 850 mL at a frequency of 15 bpm with a flow rate of 45 L/min.

a. 1:1.1
b. 1:2.5
c. 1:3.5
d. 1:4

Answer 4

ANS: B
Minute ventilation equals respiratory rate multiplied by tidal volume.

DIF: 2 REF: pg. 91

Question 5

Calculate the inspiratory to expiratory (I:E) ratio when the inspiratory time is 0.5 seconds and the respiratory rate is 30 bpm.

a. 1:3
b. 1:4
c. 4:1
d. 3:1

Answer 5

ANS: A
Total Cycle Time (TCT) = 60 sec/f; TCT – Inspiratory Time (TI) = Expiratory Time (TE); TI:TE = 1:X

DIF: 2 REF: pg. 91

Question 6

Calculate the expiratory time (TE) when the ventilator frequency is set to 25 bpm and the inspiratory time (TI) is 0.75 second.

a. 0.75 second
b. 1.16 seconds
c. 1.65 seconds
d. 2.4 seconds

Answer 6

ANS: C
Total Cycle Time (TCT) = 60 sec/f; TCT – Inspiratory Time (TI) = Expiratory Time (TE)

DIF: 2 REF: pg. 91

Question 7

What is the flow rate necessary to deliver a tidal volume (VT) of 600 mL, with a constant waveform, at a respiratory rate of 15 breaths/min with an I:E of 1:4?

a. 36 L/min
b. 40 L/min
c. 45 L/min
d. 60 L/min

Answer 7

ANS: C
Total Cycle Time (TCT) = 60 sec/f; Inspiratory Time (TI) = TCT/Inspired (I) + Expired (E); Flow rate = Tidal Volume (VT)/Inspiratory Time (TI)

DIF: 2 REF: pgs. 91, 92

Question 8

Setting flow rates high will cause which of the following to occur?

a. Improve gas exchange
b. Lengthen inspiratory time
c. Increase air trapping
d. Increase peak pressures

Answer 8

ANS: D
The flow setting on a mechanical ventilator determines how fast the inspired gas will be delivered to the patient. During continuous mandatory ventilation (CMV), high flows shorten inspiratory time (TI) and may result in higher peak pressures and poor gas distribution.

DIF: 1 REF: pg. 92

Question 9

Slow flow rates will cause which of the following to occur?

a. Poor gas exchange
b. Increase peak pressures
c. Shorten expiratory time
d. Decrease mean airway pressure

Answer 9

ANS: C
Slower flows may reduce peak pressures, improve gas distribution, and increase at the expense of increasing inspiratory time (TI). Unfortunately, shorter expiratory time (TE) can lead to air trapping, while using a longer TI may cause cardiovascular side effects.

DIF: 1 REF: pg. 92

Question 10

The flow wave form pattern that provides the shortest inspiratory time (TI) of all the available flow patterns with an equivalent peak flow rate setting is which of the following?

a. Sine
b. Constant
c. Ascending Ramp
d. Descending Ramp

Answer 10

ANS: B
Generally, a constant flow pattern provides the shortest inspiratory time (TI) of all the available flow patterns with an equivalent peak flow rate setting.

DIF: 1 REF: pg. 92

Question 11

The flow wave form pattern that is created during pressure targeted ventilation is which of the following?

a. Sine
b. Rectangular
c. Ascending Ramp
d. Descending Ramp

Answer 11

ANS: D
The descending wave form occurs naturally in pressure ventilation.

DIF: 2 REF: pg. 92

Question 12

The flow wave form pattern that will decrease peak pressure but at the same time may increase mean airway pressure is which of the following?

a. Sine
b. Rectangular
c. Ascending Ramp
d. Descending Ramp

Answer 12

ANS: D
In situations where plateau pressure (PPlateau) is critical, changing to a descending ramp in order to reduce peak pressures may increase the mean airway pressure.

DIF: 1 REF: pg. 93

Question 13

A patient having an acute, severe asthma exacerbation is intubated and set up on volume-controlled continuous mandatory ventilation (VC-CMV). To ensure volume delivery at the lowest peak pressure while providing for better air distribution, which flow wave form should be used?

a. Sine
b. Rectangular
c. Ascending Ramp
d. Descending Ramp

Answer 13

ANS: D
In patients with high airway resistance (Raw), the descending pattern is more likely to deliver a set tidal volume (VT) at a lower pressure and provide for better distribution of air through the lung than a constant or an accelerating flow.

DIF: 2 REF: pg. 92

Question 14

The most appropriate tidal volume setting for a 6’3” male ventilator patient with normal lungs is which of the following?

a. 300 mL
b. 500 mL
c. 700 mL
d. 900 mL

Answer 14

ANS: B
First calculate ideal body weight (IBW) = 106 + 6(ht – 60). Then using the range of 5 to 7 mL/kg IBW the tidal volume range for this patient is 445 mL to 623 mL.

DIF: 2 REF: pgs. 92, 93

Question 15

A 5’10” male patient with normal lungs has been intubated and requires mechanical ventilation with volume-controlled continuous mandatory ventilation (VC-CMV). The tidal volume and ventilator rate settings that should be recommended for this patient are which of the following?

a. VT = 525 mL, rate = 14 bpm
b. VT = 750 mL, rate = 12 bpm
c. VT = 825 mL, rate = 10 bpm
d. VT = 950 mL, rate = 8 bpm

Answer 15

ANS: A
First calculate ideal body weight (IBW) for a male, which is 106 + 6(ht – 60) = 75 kg. Then using the range of 5 to 7 mL/kg IBW, the tidal volume range for this patient is 375 mL to 525 mL. Minute ventilation is about 100 mL/kg IBW. Therefore, minute ventilation should be approximately 7.5 L/min. Dividing the calculated minute ventilation by the tidal volume range for this patient provides a range of rates for the tidal volumes: 14 to 20 bpm depending on the set volumes. The most appropriate volume and rate combination for this patient is 525 mL × 14 bpm = 7.35 L/min.

DIF: 2 REF: pgs. 90, 91

Question 16

A 5’2” female patient with normal lungs has been intubated and requires mechanical ventilation with volume-controlled continuous mandatory ventilation (VC-CMV). The tidal volume (VT) and ventilator rate settings that should be recommended for this patient are which of the following?

a. VT = 315 mL, rate = 20 bpm
b. VT = 364 mL, rate = 14 bpm
c. VT = 468 mL, rate = 12 bpm
d. VT = 563 mL, rate = 10 bpm

Answer 16

ANS: B
First calculate ideal body weight (IBW) for a female, which is 105 + 5(ht – 60) = 52 kg. Then using the range of 5 to 7 mL/kg IBW the tidal volume range for this patient is 260 mL to 364 mL. Minute ventilation is about 100 mL/kg IBW. Therefore, minute ventilation should be approximately 5.2 L/min. Then dividing the calculated minute ventilation by the tidal volume range for this patient provides a range of rates for the tidal volumes: 14 to 20 bpm depending on the set volumes. The most appropriate volume and rate combination for this patient is 364 mL × 14 bpm = 5.1 L/min.

DIF: 2 REF: pg. 91

Question 17

A 47-year-old, 5’6”, 112 lb female patient, is still under the effects of anesthesia following a hysterectomy. Her body temperature is 37° C. She has no history of lung disease. The appropriate initial minute ventilation for this patient is which of the following?

a. 5.1 L/min
b. 6.1 L/min
c. 11.2 L/min
d. 13.5 L/min

Answer 17

ANS: B
First calculate ideal body weight (IBW) for a female, using the formula 105 + 5(ht – 60). This patient’s IBW is 61 kg. Minute ventilation is about 100 mL/kg IBW, which would be 61,000 mL/min or 6.1 L/min.

DIF: 2 REF: pg. 90

Question 18

A 26-year-old, 6’6”, 250 lb male patient, is still under the effects of anesthesia following knee surgery. His body temperature is 37° C. He has no history of lung disease. The appropriate initial minute ventilation for this patient is which of the following?

a. 8.9 L/min
b. 9.7 L/min
c. 11.4 L/min
d. 13.6 L/min

Answer 18

ANS: B
First calculate ideal body weight (IBW) for a male, using the formula 106 + 6(ht – 60). This patient’s IBW is 97 kg. Minute ventilation is about 100 mL/kg IBW, which would be 97,000 mL/min or 9.7 L/min.

DIF: 2 REF: pgs. 90, 91

Question 19

A 39-year-old, 5’4”, 138 lb female patient requires intubation and mechanical ventilation. Her body temperature is 39° C. She has no history of lung disease. The appropriate initial minute ventilation for this patient is which of the following?

a. 5.7 L/min
b. 6.8 L/min
c. 7.6 L/min
d. 13.8 L/min

Answer 19

ANS: B
First calculate ideal body weight (IBW) for a female, using the formula 105 + 5(ht – 60). This patient’s IBW is 57 kg. Minute ventilation is about 100 mL/kg IBW, which would be 57,000 mL/min or 5.7 L/min. VE would have to be increased by 10% for each degree above 37° C: a total increase of 20% of 5.7 = 1.14; therefore, the new minute ventilation (VE) would be 5.7 + 1.14 = 6.8 L/min.

DIF: 2 REF: pg. 88

Question 20

A patient has a body temperature of 40° C. How should the initial minute ventilation setting be adjusted?

a. Increase it by 15%
b. Decrease it by 18%
c. Decrease it by 25%
d. Increase it by 30%

Answer 20

ANS:	D
Minute ventilation (VE) would have to be increased by 10% for each degree above 37° C.

DIF: 1 REF: pg. 88

Question 21

The pattern that has been shown to improve the distribution of gas in the lungs for an intubated patient on volume-controlled continuous mandatory ventilation (VC-CMV) is which of the following?

a. Sine waveform
b. Ascending ramp
c. Descending ramp
d. Square waveform

Answer 21

ANS: C
Studies comparing the descending flow pattern with the constant flow pattern suggest that the descending flow pattern improves the distribution of gas in the lungs.

DIF: 1 REF: pg. 93

Question 22

A 47-year-old, 6’1” male patient is admitted to the hospital due to trauma from a motor vehicle accident. Forty-eight hours post admission, the patient is suffering from respiratory distress with severe hypoxemia and is intubated. A chest x-ray, done prior to intubation , reveals a ground glass appearance bilaterally. The physician requests the volume-controlled continuous mandatory ventilation (VC-CMV) mode for this patient. The initial settings for the ventilator should be which of the following?

a. VT = 450 mL, rate = 18 bpm, PEEP = 8 cm H2O
b. VT = 600 mL, rate = 10 bpm, PEEP = 5 cm H2O
c. VT = 750 mL, rate = 15 bpm, PEEP = 10 cm H2O
d. VT = 900 mL, rate = 12 bpm, PEEP = 5 cm H2O

Answer 22

ANS: A
First calculate ideal body weight (IBW) for a male, using the formula 106 + 6(ht – 60). This patient’s IBW is 84 kg. Minute ventilation is about 100 mL/kg IBW, which would be 8.4 L/min. Since the patient appears to have Acute Respiratory Distress Syndrome (ARDS) the tidal volume should be set to between 4 and 6 mL/kg. This would make the appropriate tidal volume range 336 mL to 504 mL. This eliminates all of the choices except “A.” Dividing the tidal volume range into 8.4 L/min gives the set rate range at 17 to 25 bpm. This also eliminates all but choice “A.”

DIF: 3 REF: pgs. 90, 91

Question 23

A 65-year-old, 73-inch-tall, 195 lb male patient was admitted 2 days ago for renal failure. The patient has a history of Chronic Obstructive Pulmonary Disease (COPD) and has a pulse of 122 bpm, BP 153/88, and temperature 37° C. The patient is intubated for acute-on-chronic respiratory failure with hypoxemia. The physician requests volume-controlled continuous mandatory ventilation (VC-CMV). The initial settings for the ventilator should be which of the following?

a. VT = 700 mL, rate = 12 bpm, PEEP = 3 cm H2O
b. VT = 900 mL, rate = 10 bpm, PEEP = 5 cm H2O
c. VT = 450 mL, rate = 20 bpm, PEEP = 8 cm H2O
d. VT = 800 mL, rate = 15 bpm, PEEP = 10 cm H2O

Answer 23

ANS: A
First calculate ideal body weight (IBW) for a male, using the formula 106 + 6(ht – 60). This patient’s IBW is 84 kg. Minute ventilation is about 100 mL/kg IBW, which would be 8.4 L/min. Since the patient has a history of Chronic Obstructive Pulmonary Disease (COPD), the tidal volume should be set to between 8 and 10 mL/kg with rates of between 8 and 12 bpm.. This would make the appropriate tidal volume range 672 mL to 840 mL. This eliminates the two choices where the volume is outside of this range, leaving choices “A” and “D.” Choice “D” can be eliminated because the rate of 15 is outside the suggested rates for COPD patients. Rapid rates will lead to air trapping in patients with high airway resistance.

DIF: 3 REF: pgs. 90, 91

Question 24

With which flow waveform pattern will the mean airway pressure be the highest?

a. Sine
b. Square
c. Ascending ramp
d. Descending ramp

Answer 24

ANS: D
The descending ramp flow pattern keeps mean airway pressure high and may improve gas distribution.

DIF: 1 REF: pg. 93