MECHANICAL VENTILATION 8TH
EDITION BY J.M. CAIRO LATEST
UPDATED VERSION, GRADED
A+
, Chapter 1: Basic Terms and Concepts of Mechanical
Ventilation
Complete Chapter | 65 Questions with Answers and Rationales
1. Which of the following best defines mechanical ventilation?
A) The use of a machine to deliver oxygen to a patient without any positive pressure
B) The use of a machine to assist or replace spontaneous breathing by delivering gas
under positive pressure
C) The manual delivery of breaths using a bag-valve-mask device
D) The administration of oxygen via nasal cannula for respiratory support
Answer: B
Rationale: Mechanical ventilation is defined as the use of a machine (ventilator) to assist
or replace spontaneous breathing by delivering gas under positive pressure to the
airways and lungs. This distinguishes it from supplemental oxygen delivery (nasal
cannula, mask) which does not provide positive pressure support. Mechanical ventilation
is indicated when a patient cannot maintain adequate gas exchange or airway
protection on their own. Positive pressure ventilation can be delivered invasively (via
endotracheal tube or tracheostomy) or noninvasively (via mask).
2. Positive pressure ventilation differs from negative pressure ventilation in that:
A) Positive pressure pushes air into the lungs during inspiration
B) Negative pressure pushes air into the lungs during inspiration
, C) Positive pressure creates a vacuum to draw air into the lungs
D) Negative pressure requires an endotracheal tube
Answer: A
Rationale: Positive pressure ventilation pushes air into the lungs during inspiration,
increasing intrathoracic pressure. Negative pressure ventilation (e.g., iron lung) creates a
vacuum around the chest, drawing air into the lungs by expanding the thoracic cavity.
Understanding this distinction is fundamental to comprehending the physiological
effects of mechanical ventilation, particularly the hemodynamic consequences of
increased intrathoracic pressure. Positive pressure is the standard for modern
mechanical ventilation.
3. Transrespiratory pressure (Ptrans) is defined as:
A) The pressure difference between the alveoli and the body surface
B) The pressure difference between the airway opening and the alveoli
C) The pressure difference between the pleural space and the body surface
D) The pressure difference between the airway opening and the body surface
Answer: D
Rationale: Transrespiratory pressure (Ptrans) is the pressure difference between the
airway opening (Pao) and the body surface (Pbs). This is the total pressure required to
move gas into the respiratory system. Transairway pressure (Pta) is the difference
between the airway opening and the alveoli, while transthoracic pressure (Ptt) is the
difference between the alveoli and the body surface. Understanding these pressure
gradients is essential for analyzing the work of breathing and the effects of mechanical
ventilation.
, 4. A patient receiving mechanical ventilation has a plateau pressure (Pplat) of 28
cm H₂O and a peak inspiratory pressure (PIP) of 38 cm H₂O. The difference
between these pressures represents:
A) Transrespiratory pressure
B) Airway resistance
C) Lung compliance
D) Auto-PEEP
Answer: B
Rationale: The difference between peak inspiratory pressure (PIP) and plateau pressure
(Pplat) represents the pressure required to overcome airway resistance. PIP is measured
at the end of inspiration during volume-controlled ventilation and reflects both resistive
and elastic pressures. Pplat is measured during an inspiratory hold and reflects only
elastic pressure (lung and chest wall compliance). An increased PIP-Pplat gradient (>5-
10 cm H₂O) indicates increased airway resistance from conditions such as
bronchospasm, secretions, or endotracheal tube obstruction.
5. Plateau pressure (Pplat) measured during volume-controlled ventilation reflects:
A) Airway resistance
B) Lung and chest wall compliance (elastic recoil)
C) Auto-PEEP
D) Peak inspiratory flow rate
Answer: B
Rationale: Plateau pressure (Pplat) is measured during an inspiratory hold maneuver
when flow is zero, eliminating resistive pressure. Pplat reflects the elastic recoil pressure
of the respiratory system (lung and chest wall compliance). Clinically, Pplat should be
maintained ≤ 30 cm H₂O to reduce the risk of ventilator-induced lung injury (VILI).