The association of acute hypercarbia and plasma potassium concentration during laparoscopic surgery: a retrospective observational study.

BACKGROUND

It is uncertain whether increases in PaCO during surgery lead to an increase in plasma potassium concentration and, if so, by how much. Hyperkalaemia may result in cardiac arrhythmias, muscle weakness or paralysis. The key objectives were to determine whether increases in PaCO during laparoscopic surgery induce increases in plasma potassium concentrations and, if so, to determine the magnitude of such changes.

METHODS

A retrospective observational study of adult patients undergoing laparoscopic abdominal surgery was perfomed. The independent association between increases in PaCO and changes in plasma potassium concentration was assessed by performing arterial blood gases within 15 min of induction of anaesthesia and within 15 min of completion of surgery.

RESULTS

289 patients were studied (mean age of 63.2 years; 176 [60.9%] male, and mean body mass index of 29.3 kg/m). At the completion of the surgery, PaCO had increased by 5.18 mmHg (95% CI 4.27 mmHg to 6.09 mmHg) compared to baseline values (P < 0.001) with an associated increase in potassium concentration of 0.25 mmol/L (95% CI 0.20 mmol/L to 0.31 mmol/L, P < 0.001). On multiple regression analysis, PaCO changes significantly predicted immediate changes in plasma potassium concentration and could account for 33.1% of the variance (r = 0.331, f(3,259) = 38.915, P < 0.001). For each 10 mmHg increment of PaCO the plasma potassium concentration increased by 0.18 mmol/L.

CONCLUSION

In patients receiving laparoscopic abdominal surgery, there is an increase in PaCO at the end of surgery, which is independently associated with an increase in plasma potassium concentration. However, this effect is small and is mostly influenced by intravenous fluid therapy (Plasma-Lyte 148 solution) and the presence of diabetes. Trial registration Retrospectively registered in the Australian New Zealand Clinical Trials Registry (Trial Number: ACTRN12619000716167).