Is it time to rethink about protocols for managing intraoperative serum potassium and blood glucose levels during off-pump coronary artery bypass surgery?
Kapil Gupta1, Pankaj Devi Dayal2, Shyam Bhandari3, Amitabh Kumar4, Carla Todaro5, Anoop R Gogia1, Poonam Malhotra6
1 Department of Anesthesia, Vardhman Mahavir Medical College and Safdarjung Hospital, New Delhi, India
2 Department of Anesthesia, Neuroscience Clinical and Research Center, Patliputra, Patna, Bihar, India
3 Department of Anesthesia, Dr Rajendra Prasad Medical College, Kangra, Himachal Pradesh, India
4 Department of Anesthesia, Orchid Hospital, Janakpuri, New Delhi, India
5 Department of Anesthesia, London Health Science Center, Schulich Western University, London, ON, Canada
6 Department of Cardiac Anesthesia, All India Institute of Medical Sciences, New Delhi, India
Dr. Kapil Gupta
Department of Anesthesia, Vardhman Mahavir Medical College and Safdarjung Hospital, New Delhi, 110029
Source of Support: None, Conflict of Interest: None
Background A low perioperative serum potassium level (<4 mEq/l) and high blood glucose level (>200 mg/dl) during cardiac surgery is a preventable cause of high morbidity and mortality. In this study, we measured the changes in intraoperative levels of serum potassium and blood glucose in adult patients undergoing elective off-pump coronary artery bypass (OPCAB) surgery, while administering insulin intraoperatively as per the present guidelines.
Patients and methods Thirty-six adults, aged 18–65 years, undergoing elective OPCAB surgery were enrolled in this study. Arterial blood gas analysis was performed at predetermined intraoperative time points to measure serum potassium and blood glucose levels as primary variables. Base excess, pH, and HCO3− were recorded as secondary variables. Insulin infusion was started according to the sliding scale, whenever blood glucose was more than 180 mg/dl. Intravenous potassium was supplemented, when serum potassium was less than 4 mEq/l. Quantitative variables were compared with baseline using paired t test and repeated measure analysis of variance was used for comparison across follow up.
Results Potassium chloride had to be continuously administered intravenous to maintain serum potassium levels more than 4 mEq/l throughout OPCAB surgery. There was a highly significant (P<0.001) increase in the intraoperative blood glucose level compared with the baseline throughout the OPCAB surgery.
Conclusion Patients are prone to hypokalemia and hyperglycemia during OPCAB surgery, despite following the current guidelines. More studies are needed to formulate a better insulin infusion protocol for maintaining normoglycemia and guidelines need to be formulated for continuous intraoperative potassium infusion during OPCAB surgery.