Question

An 84-kg (185-lb) 6-ft 1-in (185-cm) male is receiving mechanical ventilation by a volume-controlled ventilator in the assist/control mode on the following settings:

Mandatory rate 18/min
VT 650 mL FIO2 0.4 PEEP 5 cm H₂O ABGs: pH 7.28 PaCO₂ 56 mm Hg PO2 71 mm Hg HCO₃⁻ 27 mEq/L BE +3 mEq/L
Which of the following represents the most appropriate action?
1) increase FIO2 to 0.5
2) increase rate to 20
3) increase PEEP to 8 cmH₂O
4) increase VT to 550

Answer 1

The patient exhibits signs of respiratory acidosis. The appropriate action to address this condition is to increase the elimination of CO2. Increasing the respiratory rate to 20 breaths per minute is the most suitable choice from the given options.

Step-by-step explanation:

The patient's arterial blood gases (ABGs) show a pH of 7.28 and a PaCO₂ of 56 mm Hg, indicating a state of respiratory acidosis. The partial pressure of oxygen (PO₂) is 71 mm Hg, which is on the lower end of normal but does not indicate severe hypoxemia. The patient is currently on a ventilator with a mandatory rate of 18 breaths per minute, a tidal volume (VT) of 650 mL, a fractional inspired oxygen (FIO₂) of 0.4, and positive end-expiratory pressure (PEEP) of 5 cm H₂O.

To correct respiratory acidosis, we should aim to increase the removal of CO₂ by the lungs, which can be achieved by increasing the rate or tidal volume. Since the current tidal volume is within the normal range, it is more appropriate to increase the respiratory rate rather than further increasing the tidal volume which might risk lung injury with high volumes. Therefore, the most appropriate action from the given options would be to increase the rate to 20 breaths per minute (option 2).