1 Department of Anaesthesiology and Intensive Care and 2 The Institute of Clinical Pharmacology, The Chaim Sheba Medical Centre, Tel Hashomer, Israel 52621 *Corresponding author
Accepted for publication: April 22, 2002
![]() |
Abstract |
---|
![]() ![]() ![]() ![]() ![]() ![]() |
---|
Methods. We gave esmolol 80 mg to 30 healthy male patients after induction of anaesthesia using propofol, with either fentanyl (group 1) or placebo (group 2). Patients were ventilated mechanically through a laryngeal mask airway and anaesthesia was maintained using propofol to keep the BIS value between 55 and 60.
Results. Esmolol did not affect the BIS index value in either group. In group 1, the areas (mean (SD)) under the BIS vs time curve 3 min before and 3 min after esmolol administration were 145 (9) and 146 (8) respectively (P=0.116). In group 2 values were 147 (8) and 146 (7) respectively (P=0.344). In contrast, in group 1 the area under the systolic arterial pressure (SAP) curve was 299 (31) before and 270 (29) after esmolol (P<0.001), and 156 (17) and 141 (17) respectively for heart rate (P<0.001). In group 2 values were 326 (36) and 302 (41) for SAP (P<0.001) and 182 (25) and 155 (22) for heart rate (P<0.001).
Conclusions. The results suggest that a single dose of esmolol affects the SAP and heart rate but does not affect BIS values.
B J Anaesth 2002; 89: 50911
Keywords: anaesthesia, depth of anaesthesia; anaesthetics i.v., propofol; analgesics opioid, fentanyl; antagonists, esmolol; monitoring, bispectral index
![]() |
Introduction |
---|
![]() ![]() ![]() ![]() ![]() ![]() |
---|
Because esmolol appears to affect EEG activity, we studied its effects by using the bispectral index scale (BIS; Aspect Medical Systems, Natick, MA, USA), which is a processed EEG recently introduced to monitor the depth of anaesthesia.7
![]() |
Methods and results |
---|
![]() ![]() ![]() ![]() ![]() ![]() |
---|
Patients were monitored during the study using ECG, a pulse oximeter and a capnograph. Systolic arterial pressure (SAP) was measured at 1-min intervals and heart rate (HR) was monitored continuously. The BIS (version 3.12; Aspect Medical Systems, Natick, MA, USA) was measured continuously.
On arrival in the operating room, patients were randomly assigned to one of two groups by an independent observer. Group 1 received fentanyl 2 µg i.v. and group 2 patients received placebo, in a double-blind fashion. In both groups a dose of propofol 2.5 mg kg1 was followed by a continuous infusion of 5 mg kg1 h1. Additional propofol was given in doses of 0.5 mg kg1 to keep the BIS between 55 and 60. After insertion of a laryngeal mask airway, patients were ventilated using pressure-controlled mode with an initial pressure of 16 cm H2O, a respiratory rate of 10, an inspiratory to expiratory ratio of 1:2 and 50% oxygen with 50% nitrous oxide. The ventilator was adjusted to keep end-tidal carbon dioxide at 2832 mm Hg.
When SAP, HR and BIS values had been stable for 5 min, esmolol 80 mg was given in both groups and recordings were made for 3 min. During this period surgery was not allowed to progress.
The patients age was 29 (18-49) yr in group 1 and 30 (19-50) yr in group 2 and weight was 80 (12) kg in group 1 and 81 (9) kg in group 2.
In group 1, esmolol reduced SAP from 119 (13) mm Hg to a minimum value of 105 (10) mm Hg after 2 min. In group 2 the values were 130 (16) and 120 (17) mm Hg respectively. HR decreased from 62 (7) to 55 (7) beats min1 in group 1 and from 72 (10) to 61 (9) beats min1 in group 2. BIS values before esmolol administration were 58 (5) in group 1 and 59 (3) in group 2. Values had not changed 3 min after esmolol administration.
Using SigmaStat software (Jadel Corporation, Access Softeck Inc., Chicago, IL, USA), the values of each variable (SAP, HR and BIS) 3 min before and 3 min after esmolol were plotted against time. The areas under the curves (AUC) before and after esmolol were then compared using a paired t-test.
Esmolol reduced SAP in both groups (Table 1). In group 1 the AUC for SAP vs time was 299 (31) before and 270 (29) after esmolol (P<0.001). In group 2, values were 326 (36) and 302 (41) respectively (P<0.001). Esmolol changed the HR. In group 1 the AUC of the HR over time was 156 (17) before esmolol, and 141 (17) after esmolol (P<0.001). In group 2, values were 182 (25) and 155 (22) respectively (P<0.001). In contrast, esmolol did not affect the BIS index. The AUC for BIS over time were 145 (9) before esmolol and 146 (8) after esmolol in group 1 (P=0.116), and 147 (8) and 146 (7) respectively in group 2 (P=0.344).
|
![]() |
Comments |
---|
![]() ![]() ![]() ![]() ![]() ![]() |
---|
How esmolol affects the depth of anaesthesia and EEG activity is unclear as the drug does not cross the bloodbrain barrier. In some studies, opiates were necessary in order to achieve its effects,4 suggesting that esmolol may affect opiate kinetics by altering cardiac function and hepatic blood flow rather than by an independent pharmacodynamic effect. In a similar way, esmolol (0.5 mg kg1) increased the onset time of rocuronium-induced muscle relaxation. The onset time was shorter after ephedrine, and the effect was attributed to the effect on cardiac output.10 In the present study the lack of effect of esmolol on the BIS might be attributed to the dose of fentanyl (only 2 µg kg1) or to the timing of opiate administration (a few minutes before esmolol). A direct effect of esmolol, an effect of a metabolite or a secondary process are possible explanations for the change in BIS found in other studies.9
In conclusion, our study does not show that a single dose of esmolol affects the BIS index, even though cardiovascular effects were seen.
![]() |
References |
---|
![]() ![]() ![]() ![]() ![]() ![]() |
---|
2 Urban MK, Markowitz SM, Gordon MA, Urquhart BL, Kligfield P. Postoperative prophylactic administration of beta-adrenergic blockers in patients at risk for myocardial ischemia. Anesth Analg 2000; 90: 125761
3 Johansen JW, Flaishon R, Sebel PS. Esmolol reduces anaesthetic requirement for skin incision during propofol/nitrous oxide/morphine anesthesia. Anesthesiology 1997; 86: 36471[ISI][Medline]
4 Johansen JW, Schneider G, Windsor AM, Sebel PS. Esmolol potentiates reduction of minimum alveolar isoflurane concentration by alfentanil. Anesth Analg 1998; 87: 6716[Abstract]
5 Orme R, Leslie K, Umranikar A, Ugoni A. Esmolol and anesthetic requirement for loss of responsiveness during propofol anesthesia. Anesth Analg 2002; 94: 1126
6 Van den Broek WW, Leentjens AF, Mulder PG, Kusuma A, Bruijn JA. Low-dose esmolol bolus reduces seizure duration during electroconvulsive therapy: a double blind, placebo-controlled study. Br J Anaesth 1999; 83: 2714
7 Andrzejowski J, Sleigh JW, Johnson IA, Sikiotis L. The effect of intravenous epinephrine on the bispectral index and sedation. Anaesthesia 2000; 55: 7613[ISI][Medline]
8 Johansen JW, Sebel PS. Development and clinical application of electroencephalographic bispectrum monitoring. Anesthesiology 2000; 93: 133644[ISI][Medline]
9 Johansen JW. Esmolol promotes electroencephalographic burst suppression during propofol/alfentanil anesthesia. Anesth Analg 2001; 93: 152631
10 Szmuk P, Ezri T, Chelly JE, Katz J. The onset time of rocuronium is slower by esmolol and accelerated by ephedrine. Anesth Analg 2000; 90: 12179