Quantitative Analysis of Hypercarbia and Ventilator Settings During a Robot Assisted Laparoscopy

Subcutaneous emphysema is a common surgical complication during laparoscopic surgeries, which can cause severe respiratory acidosis if unrecognized and untreated. In this paper, we will review respiratory physiology and propose a diagnostic criterion for subcutaneous emphysema. We present a case of progressive respiratory acidosis complicated by hyperkalemia and delayed emergence during robotic surgery secondary to subcutaneous emphysema in the setting of carbon dioxide insufflation. Normally respiratory acidosis due to carbon dioxide insufflation increases carbon dioxide production by about 30%, this can be countered intraoperatively with an increase in minute ventilation. In our case, despite increases in minute ventilation, the end-tidal carbon dioxide remained elevated. The respiratory acidosis caused mild hyperkalemia which was treated intraoperatively. Post-operative chest radiograph confirmed the etiology of subcutaneous emphysema. In this case, we show that the product of the partial pressure of carbon dioxide and respiratory rate is proportional to the carbon dioxide production, and when the respiratory rate is more than twice that of the patients baseline to maintain a normal end-tidal carbon dioxide, then subcutaneous emphysema should be highly suspected.