Seesawing end-tidal carbon dioxide: portent of critical carbon dioxide embolism in retroperitoneoscopy

Abstract

An abrupt increase in end-tidal CO₂ (EtCO₂; from 35 to 58 mm Hg) followed by a sudden fall (to 18 mm Hg) was noted during retroperitoneoscopic adrenalectomy under general anaesthesia in a 23-year-old patient with adrenal hyperplasia. This was accompanied by hypotension (systolic blood pressure of 60 mm Hg), desaturation (88% SpO2) and ST depression (3.5 mm). The patient was resuscitated with fluids and vasopressor drugs and about 4 mL of air was aspirated through the central venous catheter, confirming the diagnosis of an intraoperative gas embolism. Later, a rent in the adrenal vein extending into the inferior vena cava was discovered and sutured. The blood pressure, EtCO₂, ST segment and pulse oximetry returned to normal after 15 min. This case demonstrates that gas embolism may transpire during retroperitoneoscopic adrenalectomy and an acute rise followed by a sharp fall in EtCO₂ should alert the anaesthesiologist to this rare but potentially fatal complication.

Keywords: anaesthesia; pituitary disorders.

Figure 1

Positioning in retroperitoneoscopic surgery: patient was placed in the prone position with hips flexed, anterior abdomen free from pressure and upper limbs flexed at the shoulders and elbows to optimise surgeon’s access to the adrenal gland below the 12th rib.

Figure 2

Capnogram depicting the sudden rise in end-tidal CO₂ followed by an abrupt fall well below normal, characteristic of clinically significant carbon dioxide embolism.

Figure 3

Endoscopic image of the right adrenal vein, just prior to dissection of the tumour off the adjacent segment of the inferior vena cava.