Question 1

Which of the following lung units would be most prone to air-trapping?

Accepted Answer

Air-trapping occurs with incomplete emptying of lung units. Lung units prone to air-trapping are those with long-time constants (i.e., with high resistance or high compliance).

Question 2

Ventricular dysfunction occurs in patients receiving positive-pressure ventilation for which of the following reasons?
1) Hypovolemia
2) Excessive tidal volume
3) Receiving more than optimal positive end expiratory pressure (PEEP)
4) Hypervolemia

Accepted Answer

Ventricular dysfunction in patients receiving positive-pressure ventilation can occur due to hypovolemia, excessive tidal volume, and receiving more than the optimal positive end-expiratory pressure (PEEP). Hypovolemia can reduce preload, excessive tidal volumes can increase intrathoracic pressure and impair venous return, and excessive PEEP can also increase intrathoracic pressure, leading to decreased venous return and cardiac output.

Question 3

Which of the following gastrointestinal conditions are commonly associated with long-term positive-pressure ventilation (PPV)?
1) Bleeding
2) Ulceration
3) Diarrhea

Accepted Answer

1 and 2 (Bleeding and Ulceration) are commonly associated with long-term positive-pressure ventilation due to stress-related mucosal damage and potential for stress ulcers. Diarrhea is not directly associated with PPV.

Question 4

Types of damage associated with pulmonary barotrauma include which of the following?
1) Pneumoconiosis
2) Pneumomediastinum
3) Pneumothorax
4) Subcutaneous emphysema

Accepted Answer

Pneumomediastinum, pneumothorax, and subcutaneous emphysema are types of damage associated with pulmonary barotrauma, which occurs when a rapid change in air pressure damages the lungs. Pneumoconiosis, on the other hand, is a lung disease caused by inhaling dust particles.

Question 5

Moderate rises in pleural pressure during positive-pressure ventilation have a minimal effect on cardiac output in normal subjects. What are some reasons for this lack of effect?
1) Compensatory dilation of the large arteries
2) Compensatory increase in venomotor tone
3) Compensatory increase in the cardiac rate

Accepted Answer

Compensatory increases in venomotor tone and cardiac rate help maintain cardiac output despite moderate rises in pleural pressure during positive-pressure ventilation. Compensatory dilation of large arteries is not a primary mechanism for this effect.

Question 6

Potential effects of hyperventilation on the central nervous system include which of the following? 1) Increased O₂consumption 2) Increased cerebral vascular resistance (CVR) 3) Increased intracranial pressure (ICP)

Accepted Answer

Hyperventilation can cause a decrease in carbon dioxide levels in the blood, leading to vasoconstriction and increased cerebral vascular resistance, which can result in increased intracranial pressure. However, hyperventilation also causes an increase in oxygen consumption by the brain, which is the opposite of choice 1. Therefore, the correct answer is 2 and 3 only.

Question 7

What factors contribute to the development of auto-positive end expiratory pressure (PEEP)?
1) High expiratory Raw
2) High inspiratory flows
3) Inadequate expiratory time

Accepted Answer

Auto-PEEP occurs when there is incomplete expiration before the next breath. This can be caused by various factors, including high expiratory Raw, high inspiratory flows, and inadequate expiratory time. Choice A includes only the first two factors, which are incorrect because the third factor of inadequate expiratory time is also a contributing factor to auto-PEEP. Therefore, the correct answer is B, which includes the two correct factors of high expiratory Raw and inadequate expiratory time.

Question 8

A patient receiving long-term positive-pressure ventilation support exhibits a progressive weight gain and a reduction in the hematocrit. Which of the following is the most likely cause of this problem?

Accepted Answer

Among critically ill patients, water retention usually is evident when rapid weight gain occurs. In addition, such patients may have a reduced hematocrit, which is also consistent with hypervolemia due to water retention.

Question 9

Physical assessment indicating the presence of a tension pneumothorax includes which of the following?
1) Unequal chest excursion
2) Hyperresonance upon chest percussion
3) Absent breath sounds
4) Loud breath sounds

Accepted Answer

Unequal chest excursion (1), hyperresonance upon chest percussion (2), and absent breath sounds (3) are all signs of a tension pneumothorax. Loud breath sounds (4) are not commonly associated with this condition. Therefore, options A, C, and D are incorrect.

Question 10

Which of the following are potential effects of positive-pressure ventilation on the cardiovascular system?
1) Decreased venous return
2) Decreased cranial perfusion pressures
3) Increased pulmonary blood flow
4) Decreased ventricular stroke volume

Accepted Answer

Positive-pressure ventilation can lead to decreased venous return due to increased pressure in the thorax, which can compress the vena cava and impede blood flow back to the heart. It can also lead to decreased stroke volume due to increased intrathoracic pressure and decreased preload. However, it may increase pulmonary blood flow due to increased ventilation and oxygenation. There is no evidence that positive-pressure ventilation would lead to decreased cranial perfusion pressures.

Question 11

Which of the following mechanisms explains the impaired renal function seen in patients receiving ventilatory support with positive pressure?
1) Decreased secretion of aldosterone
2) Decreased intravascular volume
3) Increased secretion of vasopressin

Accepted Answer

Positive pressure ventilation can lead to decreased intravascular volume due to increased intrathoracic pressure, decreased venous return, and decreased cardiac output. This reduction in blood flow can impair renal function. Decreased secretion of aldosterone and increased secretion of vasopressin may play a role in fluid and electrolyte imbalance, but they are not the primary mechanisms for impaired renal function in this context.

Question 12

Positive-pressure ventilation (PPV) can reduce urinary output by how much?

Accepted Answer

In terms of direct effect, PPV can reduce urinary output as much as 30% to 50%.

Question 13

Which of the following mechanisms explains the hepatic dysfunction in patients receiving positive-pressure ventilation (PPV)?

Accepted Answer

These effects appear to be directly related to the reduction in hepatic blood flow that occurs with PPV.

Question 14

Which of the following is the best explanation for the decreased levels of atrial natriuretic hormone commonly observed among patients receiving positive-pressure ventilation?

Accepted Answer

Decreased right atrial transmural pressure is primarily responsible for the decrease in atrial natriuretic hormone, which leads to sodium retention.

Question 15

Assuming a constant rate of breathing, which of the following inspiratory-to-expiratory (I:E) ratio would tend to most greatly impair a patient's systemic diastolic pressure?

Accepted Answer

The factors of positive-pressure ventilation that may decrease the systemic diastolic pressure are high mean airway pressure, due to a high positive end expiratory pressure, high tidal volume, or long inspiratory time.

Question 16

What is traumatic injury to lung tissue caused by excessive pressure called?

Accepted Answer

High ventilation pressure has long been associated with barotrauma.

Question 17

Which of the following terms describes the lung injury associated with the release of prostanoids?

Accepted Answer

These biochemical signals cause the release of cytokines, complement, prostanoids, leukotrienes, reactive oxygen species, and proteases. The release of these substances has been called "biotrauma."

Question 18

What factor primarily determines the effect of positive-pressure ventilation (PPV) on the cardiac output?

Accepted Answer

More specifically, the decrease in left ventricular output corresponded to the increase in pleural pressure that occurred with PPV.

Question 19

Hyperventilation should generally be avoided during mechanical ventilatory support. Exceptions to this rule include:
1) Trying to calm an agitated patient.
2) Failure of other methods to reduce intracranial pressure.
3) Hypokalemia causing cardiac arrhythmias.

Accepted Answer

Hyperventilation should generally be avoided during mechanical ventilatory support. However, exceptions include (2) when other methods have failed to reduce intracranial pressure and (3) when hypokalemia has caused cardiac arrhythmias. Calming an agitated patient (1) is not a valid reason to hyperventilate as it can cause respiratory alkalosis and worsen intracranial pressure. Therefore, option C is the correct answer.

Question 20

Which of the following terms describe the lung injury associated with the use of low tidal volumes?

Accepted Answer

Lung damage may also occur when ventilating at low tidal volumes, if alveoli are allowed to deflate and reinflate repeatedly with each breath. This injury is called atelectrauma.

Quiz 46: Physiology of Ventilatory Support

Which of the following lung units would be most prone to air-trapping?

Ventricular dysfunction occurs in patients receiving positive-pressure ventilation for which of the following reasons? 1) Hypovolemia 2) Excessive tidal volume 3) Receiving more than optimal positive end expiratory pressure (PEEP) 4) Hypervolemia

Which of the following gastrointestinal conditions are commonly associated with long-term positive-pressure ventilation (PPV) ? 1) Bleeding 2) Ulceration 3) Diarrhea

Types of damage associated with pulmonary barotrauma include which of the following? 1) Pneumoconiosis 2) Pneumomediastinum 3) Pneumothorax 4) Subcutaneous emphysema

Potential effects of hyperventilation on the central nervous system include which of the following? 1) Increased O₂consumption 2) Increased cerebral vascular resistance (CVR) 3) Increased intracranial pressure (ICP)

What factors contribute to the development of auto-positive end expiratory pressure (PEEP) ? 1) High expiratory Raw 2) High inspiratory flows 3) Inadequate expiratory time

A patient receiving long-term positive-pressure ventilation support exhibits a progressive weight gain and a reduction in the hematocrit. Which of the following is the most likely cause of this problem?

Physical assessment indicating the presence of a tension pneumothorax includes which of the following? 1) Unequal chest excursion 2) Hyperresonance upon chest percussion 3) Absent breath sounds 4) Loud breath sounds

Which of the following are potential effects of positive-pressure ventilation on the cardiovascular system? 1) Decreased venous return 2) Decreased cranial perfusion pressures 3) Increased pulmonary blood flow 4) Decreased ventricular stroke volume

Which of the following mechanisms explains the impaired renal function seen in patients receiving ventilatory support with positive pressure? 1) Decreased secretion of aldosterone 2) Decreased intravascular volume 3) Increased secretion of vasopressin

Positive-pressure ventilation (PPV) can reduce urinary output by how much?

Which of the following mechanisms explains the hepatic dysfunction in patients receiving positive-pressure ventilation (PPV) ?

Which of the following is the best explanation for the decreased levels of atrial natriuretic hormone commonly observed among patients receiving positive-pressure ventilation?

Assuming a constant rate of breathing, which of the following inspiratory-to-expiratory (I:E) ratio would tend to most greatly impair a patient's systemic diastolic pressure?

What is traumatic injury to lung tissue caused by excessive pressure called?

Which of the following terms describes the lung injury associated with the release of prostanoids?

What factor primarily determines the effect of positive-pressure ventilation (PPV) on the cardiac output?

Hyperventilation should generally be avoided during mechanical ventilatory support. Exceptions to this rule include: 1) Trying to calm an agitated patient. 2) Failure of other methods to reduce intracranial pressure. 3) Hypokalemia causing cardiac arrhythmias.

Which of the following terms describe the lung injury associated with the use of low tidal volumes?

Quiz 46: Physiology of Ventilatory Support

Which of the following lung units would be most prone to air-trapping?

Ventricular dysfunction occurs in patients receiving positive-pressure ventilation for which of the following reasons? 1) Hypovolemia 2) Excessive tidal volume 3) Receiving more than optimal positive end expiratory pressure (PEEP) 4) Hypervolemia

Which of the following gastrointestinal conditions are commonly associated with long-term positive-pressure ventilation (PPV) ? 1) Bleeding 2) Ulceration 3) Diarrhea

Types of damage associated with pulmonary barotrauma include which of the following? 1) Pneumoconiosis 2) Pneumomediastinum 3) Pneumothorax 4) Subcutaneous emphysema

Potential effects of hyperventilation on the central nervous system include which of the following? 1) Increased O2 consumption 2) Increased cerebral vascular resistance (CVR) 3) Increased intracranial pressure (ICP)

What factors contribute to the development of auto-positive end expiratory pressure (PEEP) ? 1) High expiratory Raw 2) High inspiratory flows 3) Inadequate expiratory time

A patient receiving long-term positive-pressure ventilation support exhibits a progressive weight gain and a reduction in the hematocrit. Which of the following is the most likely cause of this problem?

Physical assessment indicating the presence of a tension pneumothorax includes which of the following? 1) Unequal chest excursion 2) Hyperresonance upon chest percussion 3) Absent breath sounds 4) Loud breath sounds

Which of the following are potential effects of positive-pressure ventilation on the cardiovascular system? 1) Decreased venous return 2) Decreased cranial perfusion pressures 3) Increased pulmonary blood flow 4) Decreased ventricular stroke volume

Which of the following mechanisms explains the impaired renal function seen in patients receiving ventilatory support with positive pressure? 1) Decreased secretion of aldosterone 2) Decreased intravascular volume 3) Increased secretion of vasopressin

Positive-pressure ventilation (PPV) can reduce urinary output by how much?

Which of the following mechanisms explains the hepatic dysfunction in patients receiving positive-pressure ventilation (PPV) ?

Which of the following is the best explanation for the decreased levels of atrial natriuretic hormone commonly observed among patients receiving positive-pressure ventilation?

Assuming a constant rate of breathing, which of the following inspiratory-to-expiratory (I:E) ratio would tend to most greatly impair a patient's systemic diastolic pressure?

What is traumatic injury to lung tissue caused by excessive pressure called?

Which of the following terms describes the lung injury associated with the release of prostanoids?

What factor primarily determines the effect of positive-pressure ventilation (PPV) on the cardiac output?

Hyperventilation should generally be avoided during mechanical ventilatory support. Exceptions to this rule include: 1) Trying to calm an agitated patient. 2) Failure of other methods to reduce intracranial pressure. 3) Hypokalemia causing cardiac arrhythmias.

Which of the following terms describe the lung injury associated with the use of low tidal volumes?

Potential effects of hyperventilation on the central nervous system include which of the following? 1) Increased O₂consumption 2) Increased cerebral vascular resistance (CVR) 3) Increased intracranial pressure (ICP)