Om Prakash Sanjeev1, Deepak Malviya1, Manoj Tripathi1, Prakash Kumar Dubey2. 1. Department of Anaesthesiology, Dr. RML Institute of Medical Sciences, Lucknow, Uttar Pradesh, India. 2. Department of Anaesthesiology, Indira Gandhi Institute of Medical Sciences, Patna, Bihar, India.
Sir,We read the article titled “Cardiac and renal protective effects of dexmedetomidine in cardiac surgeries: A randomized controlled trial” with great interest.[1] The authors extended further the spectrum of action and use of dexmedetomidine.Authors have studied both the cardiac and renal protective effects of dexmedetomidine in patients undergoing cardiac surgeries with cardiopulmonary bypass (CPB). We have certain queries regarding the design and method of study and with cardiac protective effects.In patient recruitment, the lower age limit is not mentioned so we could not know whether this study included pediatric population or not. Second, cardiac surgery includes a wide range of surgeries with different hemodynamics. Hence, author must specifically mention different type of surgeries included in this study. We are also confused about the use of propofol as induction agent in dose of 1.5–2 mg/kg for all cardiac surgeries because different cardiac diseases have different goals of anesthesia induction. Moreover, propofol must not have been used for induction of anesthesia in all patients irrespective of cardiac pathology.Weaning from CPB often requires some inotropic and/or vasopressor infusion. Furthermore, temporary pacemaker needs to be applied in many cases. Dexmedetomidine has central sympatholytic action. Hence, it can interfere with weaning from bypass and make weaning difficult. This study did not compare the requirement of inotropic/vasopressor infusion or requirement of temporary pacemaker between two groups. Hence, safety of dexmedetomidine cannot be ascertained from this study.About cardiac protection, dexmedetomidine infusion was started only 5 min before going on bypass. Furthermore, CPB time 65–67 min and cross-clamp time 53–55 min show that cross clamp must have been applied soon after going on bypass. It implies that only after 5–10 min of starting of infusion, cross clamp was applied and heart was isolated from the circulation. So any circulation of dexmedetomidine must not have reached the heart till cross clamp was taken off. Hence, we wish to get rationalization of starting dexmedetomidine just 5 min before going on bypass.