A patient diagnosed with sepsis who is being mechanically ventilated has a combined minute ventilation of 25 L/min with a PaCO2 of 38 mm Hg. The reason for these findings is most likely which of the following?

1. Increased CO2
2. Decreased CO2
3. Increased VD/VT
4. Decreased VD/VT
a. 1 and 3 only
b. 1 and 4 only
c. 2 and 3 only
d. 2 and 4 only

ANS: A
Metabolic rate and CO2 are elevated in patients who have fever, burns, multiple trauma, sepsis, hyperthyroidism, muscle tremors or seizures, agitation, and in those patients who have undergone multiple surgical procedures. Regardless of the cause, it is clear that E will be increased and WOB will be elevated. Increasing the ventilator rate will decrease the patient's WOB, but auto-PEEP may occur. If auto-PEEP is a factor, it may be beneficial to add enough pressure support (PS) for the spontaneous breaths to reduce WOB through the ET and circuit. Other options might include switching to PC-CMV and using sedation to reduce the patient's work.