A 38-year-old, 155 cm, 50 kg, previously health female presents to the ICU with altered mental status, tachycardia, hypotension, and high fever. She is intubated for airway protection. Her laboratory test results reveal a markedly elevated T3 and T4 level with a decrease in thyroid-stimulating hormone level consistent with thyroid storm. Her arterial blood gas shows:
Her ventilator settings are volume control, tidal volume of 350 mL, respiratory rate of 14, positive end expiratory pressure (PEEP) of 5, FiO2 of 50%.
Which of the following is the next appropriate step in management?
A. Increase tidal volume to 500 mLCorrect Answer: D
Increasing the patient’s respiratory rate to increase minute ventilation is the next appropriate step in management of this patient. The patient’s ABG is shows primary respiratory acidosis with elevation in PaCO2 levels. PaCO2 is a measure of the patient’s ventilation, whereas PaO2 is a measure of oxygenation. Elevation in PaCO2 indicates inadequate ventilation, which can be improved by increasing minute ventilation: either by increasing tidal volume or respiratory rate. Increasing the patient’s tidal volumes to 500 mL would not be recommended as this is inconsistent with lung protective ventilation strategy. So, the appropriate course of action here would be to increase respiratory rate, which in turn will decrease PaCO2 levels.
PaO2 measures the patient’s oxygenation and can be adjusted by altering the level of PEEP or fraction of inspired oxygen. Because the PaO2 is within normal range, a change in this parameter is not warranted. Similarly, a change in mode of ventilation is also not indicated.
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