RRT Respiratory Therapy 3

Question 1

A patient with myasthenia gravis crisis has a vital capacity of 12 mL/kg. The appropriate action is:

Accepted Answer

Initiate intubation and mechanical ventilation

Answer

The 20-30-40 rule recommends intubation when VC falls below 20 mL/kg in neuromuscular patients; 12 mL/kg is critical.

Question 2

Auto-PEEP (intrinsic PEEP) is MOST commonly caused by:

Accepted Answer

Insufficient expiratory time leading to air trapping

Answer

Auto-PEEP results from incomplete exhalation due to insufficient expiratory time, causing air trapping and dynamic hyperinflation.

Question 3

Which condition is associated with a decreased DLCO (diffusing capacity) with normal spirometry?

Accepted Answer

Pulmonary hypertension

Answer

Pulmonary hypertension reduces the pulmonary capillary blood volume available for gas exchange, lowering DLCO despite normal airflow.

Question 4

The recommended initial tidal volume for lung-protective ventilation in ARDS is:

Accepted Answer

6–8 mL/kg IBW

Answer

The ARDSNet protocol recommends 6 mL/kg ideal body weight (IBW) with a goal plateau pressure ≤ 30 cmH2O.

Question 5

A flow-volume loop shows a fixed flattening of both inspiratory and expiratory limbs. This pattern suggests:

Accepted Answer

Fixed upper airway obstruction

Answer

Fixed obstruction (e.g., tracheal stenosis) flattens both limbs equally because the lesion does not change size with pressure changes.

RRT Exam Practice Test