Ch 323: Mechanical Ventilatory Support Flashcards Preview

Part 11 & Part 12 of Harrison's: Disorders of the Respiratory System, and Critical Care Medicine > Ch 323: Mechanical Ventilatory Support > Flashcards

Flashcards in Ch 323: Mechanical Ventilatory Support Deck (13)
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1
Q

What is the definition of hypoxemic respiratory failure?

A

Hypoxemic respiratory failure is present when arterial O2 saturation (SaO2) is < 90%, occurs despite an increased inspired O2 fraction, and usually results from ventilation-perfusion mismatch or shunt.

(p. 1740)

2
Q

What is the definition of hypercarbic respiratory failure?

A

Hypercarbic respiratory failure is present when arterial carbon dioxide (PCO2) is elevated, usually >50 mmHg, and results from conditions that decrease minute ventilation or increase physiologic dead space such that alveolar ventilation is inadequate to meet metabolic demands.

3
Q

Morphine can promote _________ release from tissue mast cells and may worsen bronchospasm in patients with asthma.

A

histamine

(p. 1741)

4
Q

Depolarizing agents such as succinylcholine should not be used in patients with…

A

…renal failure, tumor lysis syndrome, crush injuries, muscular dystrophy syndromes, and any condition associated with elevated K+ levels.

(p. 1741)

5
Q

What is the most widely used mode of ventilation?

A

assist-control ventilation (ACMV)

(p. 1741)

6
Q

What is the ventilatory rate determined by in ACMV mode?

A

the programmed backup rate or the patient’s intrinsic respiratory rate, whichever is higher

(p. 1741)

7
Q

Respiratory alkalemia can lead to…

A

…myoclonus or seizures.

(p. 1741)

8
Q

The concept of dynamic hyperinflation leading to increased intrathoracic pressures is called…

A

…auto PEEP.

(p. 1741)

9
Q

Auto PEEP may occur if the patient’s respiratory mechanics are such that…

A

…there is inadequate time for complete exhalation between inspiratory cycles.

(p. 1741)

10
Q

SIMV differs from ACMV in that only a…

A

…present number of breaths are ventilator-assisted.

(p. 1741)

11
Q

Explain how SIMV works.

A

Mandatory breaths are delivered in synchrony with the patient’s inspiratory efforts at a frequency determined by the operator. If the patient fails to initiate a breath, the ventilator delivers a fixed-tidal-volume breath and resets the internal timer for the next inspiratory cycle.

(p. 1741)

12
Q

What are the 4 core principles of protective ventilatory strategy?

A

(1) Set a target tidal volume close to 6 mL/kg of ideal body weight.
(2) Prevent plateau pressure (static pressure in the airway at the end of inspiration) exceeding 30 cm H2O.
(3) Use the lowest possible fraction of inspired oxygen (Fio2) to keep the Sao2 at ≥90%.
(4) Adjust the PEEP to maintain alveolar patency while preventing overdistention and closure/reopening.

13
Q
A