Ventilator management can be very simple or complex. As boarding continues to plague the emergency department, ventilated patients become more commonplace. The emergency physician should be well versed in ventilator settings as well as active trials regarding ventilator management.
Permissive hypercapnia was born out of ARDSnet protective lung strategies. However permissive hypercapnia does lead to respiratory academia which can scare many providers Before your run to treat the acidemia caused by your elevated CO2 consider this:
- Hypercapnia may minimize or reduce lung injury by suppressing inflammatory events
- Hypercapnia may improve lung gas exchange and increase arterial oxygenation
- Hypercapnia may inhibit the pro-inflammatory response of sepsis with studies showing lower lactates and less hypotension
There is some talk that hypercapnia may be so helpful in certain disease processes that we should be supplementing patients with CO2 through the ventilator. This is all interesting, and not ready for prime time, but perhaps you may consider ignoring the pure respiratory acidosis in your next vented patient.
Curley G. Hypercapnia and Acidosis in Sepsis: A Double-edged Sword? Anesthesiology. 2010;112:462-472
Kregenow ER. The lung and carbon dioxide: implications for permissive and therapeutic hypercapnia
Domino KB. Effect of inspired CO2 on ventilation and perfusion heterogeneity in hyperventilated dogs. J Appl Physiol 1993;95:1306-1314
Swenson ER. Effects of inspired carbon dioxide on ventilation-perfusion matching in normoxia, hypoxia and hyperoxia. Am J Respir Crit Care Med 1994;149:1563-1569.
