Question 1

Which of the following patients exhibits an acceptable ventilatory demand? V_E PaCO₂

Accepted Answer

A normal PaCO2 (partial pressure of carbon dioxide in arterial blood) range is generally considered to be between 35 and 45 mmHg. Option C, with a PaCO2 of 45, falls within this normal range, indicating an acceptable ventilatory demand.

Question 2

Which of the following oxygenation measures support a patient's readiness to wean? 1) PaO₂/PAO₂ (a/A) = 0.45 2) PaO₂/FiO₂ (P/F) = 110 3) PAO₂ - PaO₂ = 240 mm Hg 4) Physiologic shunt (Q_s/Q_t) = 12%

Accepted Answer

The correct choices are 1) a/A ratio ≥ 0.45, 3) PAO2 - PaO2 difference ≤ 300 mm Hg, and 4) Physiologic shunt (Qs/Qt) ≤ 20%, as these values indicate better oxygenation and lung function, supporting readiness for weaning from mechanical ventilation. Choice 2) P/F ratio = 110 is too low, indicating poor oxygenation.

Question 3

You measure the spontaneous rate of breathing and V_T on four patients receiving ventilator support. For which one is successful weaning most likely? Breathing frequency V_T

Accepted Answer

The successful weaning from mechanical ventilation is based on the ability of the patient to breathe spontaneously. A lower spontaneous breathing frequency indicates better recovery of respiratory muscles and normal ventilation. Patient B has a lower breathing frequency of 22, indicating a better chance of successful weaning from ventilation. The tidal volume (volume of air breathed in per breath) also plays a role, and patient B has a reasonable tidal volume of 400 ml. The other patients have higher breathing frequencies, which may indicate a weaker respiratory muscle function and less successful weaning outcomes.

Question 4

Which of the following signs observed on a mechanically ventilated patient indicate that successful weaning is unlikely?
1) Palpable scalene muscle use during inspiration
2) Palpable abdominal tensing during expiration
3) Presence of an irregular breathing pattern
4) Patient unable to alter breathing pattern on command

Accepted Answer

All of the signs listed indicate that the patient may have difficulty weaning from mechanical ventilation. Palpable scalene muscle use during inspiration suggests an increased effort to breathe. Palpable abdominal tensing during expiration suggests increased work of breathing and may be a sign of respiratory muscle fatigue. An irregular breathing pattern may be a sign of difficulty coordinating breaths or maintaining a stable respiratory rhythm. If the patient is unable to alter their breathing pattern on command, it suggests an impaired ability to initiate or sustain spontaneous breathing efforts, which would make weaning more difficult.

Question 5

When is ventilator dependence likely to occur?
1) When ventilatory capacity exceeds demand
2) When arterial hypoxemia is present
3) When the patient is malnourished
4) When the cardiovascular system is unstable

Accepted Answer

Ventilator dependence is more likely to occur when there is arterial hypoxemia (2), malnutrition (3), and cardiovascular instability (4), as these conditions impair the body's ability to maintain adequate oxygenation and perfusion, and to recover from respiratory failure, necessitating prolonged mechanical ventilation support.

Question 6

Which of the following is false about the P_0.1 measure?

Accepted Answer

Airway occlusion pressure (P_0.1) is the inspiratory pressure measured 100 msec after airway occlusion. The P_0.1 is effort independent and correlates well with central respiratory drive. Ventilator-dependent patients with COPD who have a P_0.1 greater than 6 cm H₂O tend to be difficult to wean.

Question 7

Which of the following indicate that an adult patient is ready to be weaned from ventilatory support? 1) PAO₂ - PaO₂ = 430 on 100% O₂ 2) V_D/V_T = 0.55 3) MIP = -33 cm H₂O 4) PO₂ = 76 mm Hg on 40% O₂

Accepted Answer

2) A ventilatory support weaning indicator is a low ventilatory support/tidal volume ratio (VS/VT), suggesting less effort needed to maintain adequate ventilation. 3) A maximal inspiratory pressure (MIP) more negative than -20 cm H2O indicates good respiratory muscle strength, important for weaning. 4) A partial pressure of oxygen (PaO2) greater than 60 mm Hg on less than or equal to 40% oxygen suggests adequate oxygenation, another weaning criterion.

Question 8

A patient has an adequate ventilatory reserve if which of the following is true?

Accepted Answer

Adequate ventilatory reserve means the ability of the patient to increase their minute ventilation to meet the increasing metabolic demands during exercise or physical activity. A patient has adequate ventilatory reserve if they can double their resting minute ventilation. So, option A is the correct answer. Option B refers to normal PaCO2 and minute ventilation which can be a sign of respiratory stability but not necessarily an indicator of ventilatory reserve. Option C refers to maximal inspiratory pressure and Option D refers to the ratio of dead space to tidal volume, which are not directly related to ventilatory reserve.

Question 9

Which of the following metabolic factors can hinder weaning?
1) Excessive carbohydrate feeding
2) Amino acid-based parenteral nutrition
3) Calorie intake = 1.5 . resting energy expenditure (REE)

Accepted Answer

Excessive carbohydrate feeding can lead to an increase in carbon dioxide production, which can cause respiratory distress and hinder weaning. Amino acid-based parenteral nutrition can lead to muscle wasting and weakness, which can also hinder weaning. However, calorie intake being equal to 1.5 times the resting energy expenditure (REE) is actually beneficial for weaning as it provides adequate energy for the patient's needs.

Question 10

Which of the following indicate that a patient's renal function is adequate for weaning?
1) Urine output = 20 ml/hr
2) No major weight gain
3) No edema present
4) Normal electrolytes

Accepted Answer

Adequate renal function for weaning from renal support or indicating recovery includes no major weight gain (indicating fluid balance), no edema (indicating proper fluid distribution and management), and normal electrolytes (indicating proper kidney function in regulating electrolyte balance). Urine output of 20 ml/hr is generally considered low and may indicate inadequate renal function, depending on the context and patient condition.

Question 11

Which of the following four adult patients receiving ventilatory support is the best candidate for weaning? VC V_E MVV MIF V_D/V_T

Accepted Answer

The patient has a VC of 12 mL/kg, a V_E of 8 mL/kg/min, a MVV of 22 L/min, a MIF of -22 cmH₂O, and a V_D/V_T of 0.58. This patient has a normal VC, a low V_E, a normal MVV, a normal MIF, and a normal V_D/V_T. This patient is the best candidate for weaning because they have no signs of respiratory distress.

Question 12

Successful weaning is less likely when a patient's work of breathing exceeds what level?

Accepted Answer

Successful weaning has been found to be less likely among patients with spontaneous work levels greater than 1.6 kg/m/min (16 J/min) or 0.14 kg/m/L (1.4 J/L).

Question 13

Which of the following indicate that an adult patient is ready to be weaned from ventilatory support? 1) VC = 1.9 L 2) Spontaneous rate of 32/min 3) Q_s/Q_t = 8% 4) MIP = -45 cm H₂O

Accepted Answer

1) A vital capacity (VC) of 1.9 L is generally considered adequate for weaning, as it suggests sufficient respiratory muscle strength. 3) A low QS/QT (shunt fraction) of 8% indicates good lung function, suggesting the patient may not need as much support. 4) A maximal inspiratory pressure (MIP) of -45 cm H2O is strong, indicating good respiratory muscle strength, important for weaning.

Question 14

Which of the following factors can reduce a patient's ventilatory drive?
1) Respiratory alkalosis
2) Metabolic acidosis
3) Depressant drugs
4) Decreased metabolism

Accepted Answer

Respiratory alkalosis and depressant drugs can reduce ventilatory drive by affecting the central nervous system. Decreased metabolism can also reduce the need for ventilation.

Question 15

Ventilatory capacity is determined by which of the following?
1) Central nervous system (CNS) drive
2) Trigger level
3) Muscle strength
4) Muscle endurance

Accepted Answer

Ventilatory capacity is influenced by the central nervous system (CNS) drive, which regulates the respiratory rate and volume, muscle strength, which determines the ability to generate the pressure necessary for ventilation, and muscle endurance, which affects the ability to sustain ventilation over time. Trigger level is not directly related to ventilatory capacity but rather to the sensitivity of the respiratory control system to initiate breaths.

Question 16

What is the most important prerequisite for weaning a patient from ventilatory support?

Accepted Answer

The single most important criterion to consider when evaluating a patient for ventilator discontinuation or weaning is whether there has been significant alleviation or reversal of the disease state or condition that necessitated use of the ventilator in the first place.

Question 17

Above what pressure-time index (PTI) will most patients be unable to sustain spontaneous breathing?

Accepted Answer

A PTI greater than 0.15 to 0.18 has been associated with diaphragmatic fatigue, and a PTI greater than 0.15 cannot be sustained indefinitely.

Question 18

A patient receiving ventilator support has a spontaneous rate of breathing of 26/min and an average V_T of 300 ml. What is this patient's rapid-shallow breathing index?

Accepted Answer

The rapid-shallow breathing index (RSBI) is calculated by dividing the respiratory rate by the tidal volume in liters. For this patient, the RSBI = 26 breaths/min / 0.3 L = 86.67, which rounds to 87.

Question 19

What is the least reliable weaning index?

Accepted Answer

With respect to the more traditional weaning indices, vital capacity can be highly variable, whereas MIP, minute ventilation, respiratory rate (f), and f/V_T tend to be more reliable.

Question 20

Which method of weaning may be useful to minimize auto-PEEP?

Accepted Answer

The answer of Which method of weaning may be useful...

Quiz 52: Discontinuing Ventilatory Support

Which of the following patients exhibits an acceptable ventilatory demand? VE PaCO2

Which of the following oxygenation measures support a patient's readiness to wean? 1) PaO2/PAO2 (a/A) = 0.45 2) PaO2/FiO2 (P/F) = 110 3) PAO2 - PaO2 = 240 mm Hg 4) Physiologic shunt (Qs/Qt) = 12%

You measure the spontaneous rate of breathing and VT on four patients receiving ventilator support. For which one is successful weaning most likely? Breathing frequency VT

When is ventilator dependence likely to occur? 1) When ventilatory capacity exceeds demand 2) When arterial hypoxemia is present 3) When the patient is malnourished 4) When the cardiovascular system is unstable

Which of the following is false about the P0.1 measure?

Which of the following indicate that an adult patient is ready to be weaned from ventilatory support? 1) PAO2 - PaO2 = 430 on 100% O2 2) VD/VT = 0.55 3) MIP = -33 cm H2O 4) PO2 = 76 mm Hg on 40% O2

A patient has an adequate ventilatory reserve if which of the following is true?

Which of the following metabolic factors can hinder weaning? 1) Excessive carbohydrate feeding 2) Amino acid-based parenteral nutrition 3) Calorie intake = 1.5 . resting energy expenditure (REE)

Which of the following indicate that a patient's renal function is adequate for weaning? 1) Urine output = 20 ml/hr 2) No major weight gain 3) No edema present 4) Normal electrolytes

Which of the following four adult patients receiving ventilatory support is the best candidate for weaning? VC VE MVV MIF VD/VT