RRT Knowledge Flashcards

A patient with ARDS on mechanical ventilation has a PaO2/FiO2 ratio of 85. According to the Berlin Definition, this classifies as which severity?

Answer: Severe ARDS

A PaO2/FiO2 ratio less than 100 mmHg with PEEP ≥5 cm H2O classifies as severe ARDS per the Berlin Definition.

Which ventilator waveform pattern indicates auto-PEEP (intrinsic PEEP) is present?

Answer: Flow fails to return to zero before next breath

Auto-PEEP occurs when expiratory flow does not return to zero baseline before the next breath begins, indicating gas trapping.

A patient receiving BiPAP at IPAP 14 / EPAP 6 cm H2O has an effective pressure support of:

Answer: 8 cm H2O

Effective pressure support on BiPAP equals IPAP minus EPAP, so 14 − 6 = 8 cm H2O.

When performing a slow vital capacity (SVC) maneuver, the patient is instructed to:

Answer: Inhale maximally then exhale slowly and completely

SVC requires a maximal inhalation followed by a slow, complete exhalation without forced effort, minimizing dynamic airway compression.

Which blood gas result is consistent with acute respiratory alkalosis?

Answer: pH 7.52, PaCO2 28, HCO3 22

A pH above 7.45 with a low PaCO2 and near-normal HCO3 indicates acute respiratory alkalosis (hyperventilation without renal compensation).

A size 8.0 endotracheal tube has an internal diameter of 8 mm. What is its approximate resistance compared to a 7.0 tube?

Answer: Resistance is lower in the 8.0 tube

Airway resistance is inversely proportional to the fourth power of the radius (Poiseuille's Law), so the larger 8.0 mm tube has significantly lower resistance.

During a spontaneous breathing trial (SBT), which finding is the MOST reliable predictor of successful extubation?

Answer: Rapid Shallow Breathing Index (RSBI) below 105

An RSBI (f/VT) below 105 breaths/min/L is the best validated predictor of successful extubation following an SBT.