A patient receiving control-mode continuous mandatory ventilation has the following ABGs on an FiO₂ of 0.5: pH = 7.23; PCO₂ = 61 mm Hg; HCO₃^- = 26 mm Hg. The current minute ventilation (V_E) is 9.2 L/min. What new V_E would you recommend? A) 10.6 L/min B) 14.0 L/min C) 12.4 L/min D) 5.8 L/min

Question

Quizplus · Accepted Answer

The patient has respiratory acidosis, indicated by low pH and high PCO2 levels. To correct this, we need to increase minute ventilation to decrease PCO2 levels. Using the formula: 
Δ VS = 0.008 × ideal body weight × (PaCO2 - 40) / PaCO2, 
where ideal body weight is given as 70 kg, we get:

Δ VS = 0.008 × 70 × (61 - 40) / 61 = 3.60 L/min

To find the new minute ventilation, we add the delta to the current minute ventilation:

New VS = 9.2 + 3.6 = 12.8 L/min

The closest choice is C) 12.4 L/min, but this is not quite as high as the calculated value. The next closest choice is B) 14.0 L/min, which is a reasonable increase from the initial value and would help correct the acidosis more quickly.

A Patient Receiving Control-Mode Continuous Mandatory Ventilation Has the Following