Question

A patient is weaning from mechanical ventilation on the following ventilator settings: Mode SIMV, Mandatory rate 6/min, Total rate 30/min, VT (set) 500 mL, VT (exhaled) 220 mL, FIO2 0.40, PEEP 5 cmH₂O,

Pressure support 6 cmH₂O. Arterial blood gas results show:
pH 7.34, PaCO₂ 46 torr, PaO2 80 torr, HCO₃⁻ 24 mEq/L, BE -2 mEq/L.
The respiratory therapist should recommend
1) Increasing pressure support
2) Switching to assist/control mode of ventilation
3) Increasing the set tidal volume
4) Increasing PEEP to 10 cm H₂O

Answer 1

A patient weaning from ventilation with mild respiratory acidosis and reduced oxygenation should have their pressure support increased to aid in breathing and improve arterial blood gas results.

Step-by-step explanation:

Upon examining the patient's arterial blood gas results showing a pH of 7.34, a PaCO2 of 46 torr, and PaO2 of 80 torr with current ventilator settings, it is clear that the patient's respiratory status requires adjustment to improve ventilation and oxygenation. With the SIMV mode having a total rate significantly higher than the mandatory rate, and the exhaled tidal volume (VT) being less than the set VT, this suggests the patient is working hard to breathe. The ABG results indicate a mild respiratory acidosis and mildly reduced oxygenation.

Given the pressure support of 6 cmH2O is relatively low, increasing the pressure support can help reduce the patient's work of breathing by providing more assistance during spontaneous breaths. This would likely improve the exhaled tidal volume, reduce the carbon dioxide levels, and subsequently raise the pH, moving it closer to the normal range. Changing to assist/control mode, increasing the set tidal volume, or increasing PEEP are not appropriate actions given the current ABG results and the risk of volutrauma or cardiovascular compromise associated with higher PEEP levels.