Journal: Eur J Anaesthesiol 24(10):826-831, 2007. 23 References
Reprint: Dept of Anesthesiology, Faculty of Medical, Trakya University, Edirne 22030, Turkey (A Colak, MD)
Faculty Disclosure: Abstracted by T. Tilton, who has nothing to disclose.
Both esmolol and magnesium are known to attenuate hemodynamic responses to intubation. This study compared the effects of esmolol and magnesium on the hemodynamic response during the pre-extubation period in the intensive care unit (ICU) following coronary artery bypass grafting (CABG). Esmolol is a beta-adrenergic receptor antagonist with a very short duration of action and high cardio-selectivity. Esmolol was preferred in this study because it prevents postoperative myocardial ischemia and its short action depending on infusion speed. It has also been used to decrease cardiovascular responses during extubation. Magnesium inhibits catecholamine responses and causes dilatation in the coronary circulation.
A total of 120 consecutive patients undergoing CABG were included in a double-blind study. Patients were medicated preoperatively with diazepam and morphine; anesthesia consisted of fentanyl, pancuronium, and sevoflurane. At the conclusion of the CABG, patients were transferred to the ICU and mechanically ventilated. Exclusion criteria for the study included a preoperative ejection fraction < 40%, history of asthma, receiving vasodilatator and inotropic therapy by infusion, or drug allergy. All patients had received beta-blocker until 8 hours preoperatively.
When patients were determined ready for extubation, they were randomly divided into 3 groups (n=40, each): group I received esmolol 1 mg/kg; group II received magnesium 30 mg/kg; and group III received 0.9% saline. Each drug was diluted to 20 mL administered over 5 minutes.
Demographics were similar between groups. Heart rate (HR) was significantly lower in group I than in groups II and III, and in Group II versus group III during extubation. HR was also lower in group I than in group III at 1 min after extubation. A significant increase was seen at extubation and 1 minute after extubation compared to HR before the study drug in group I. HR increased significantly at and after extubation compared to pre-infusion in group III. Systolic arterial pressure (SAP) was significantly less in group I versus groups II and III at extubation, and increased significantly in groups II and III both at and after extubation. Diastolic arterial pressure (DAP) was significantly higher in group III than in the other groups both at and after extubation.
Mean arterial pressure (MAP) was significantly lower in group I than in groups II and III during extubation, lower in group II than in group III during extubation, and lower in group I than in group III after extubation. Central venous pressure was lower in group I than IN group III after extubation. Nitroglycerin (used for >20% increase in HR, SAP, DAP or MAP) was required in 2 patients in group I, 13 in group II, and 27 patients in group III.
In conclusion, hemodynamic responses were decreased with magnesium and inhibited by esmolol during extubation following CABG. A higher dose of magnesium is recommended to inhibit hemodynamic responses. |
