Multiple Choice Questions

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Chapter 15, Question 1.

15.1 A 29-week gestation infant, intubated since birth for moderate respiratory distress syndrome, has been steadily improving and is now 12 hours old. The baby was given a loading dose of caffeine at 8 hours of age. The baby is vigorous, well perfused and passing urine. Blood pressure is within normal limits. The level of ventilatory support has been progressively weaned and is currently as follows: Mode: synchronized intermittent positive pressure ventilation (SIPPV) (assist control); fractional inspired oxygen concentration (Fio₂) 0.21; peak inspiratory pressure (PIP) 12 cmH₂O; positive end-expiratory pressure (PEEP) 5 cmH₂O; set ventilator rate 30 breaths per minute; inspiratory time (IT) 0.35 second; baby's spontaneous breathing rate 50 breaths per minute. The most recent arterial blood gas is as follows: pH 7.43 [7.34–7.43]; Paco₂ 31 mmHg [31–42]; Pao₂ 68 mmHg [45–60]; bicarbonate 23 mmol l^–1 [20–26]; base excess 1.6 [-5.0–5.0]. Which one of the following would be the most appropriate next step?