Previous articleTable of Contents Next article

ARTICLE
Year : 2007  |  Volume : 1  |  Issue : 1  |  Page : 8

Effect of Bispectral index (BIS) monitoring on postoperative recovery and Sevoflurane consumption among morbidly obese patients undergoing laparoscopic gastric banding


1 Department of Anesthesia, King Khalid University Hospital, King Saud University, Riyadh, Saudi Arabia
2 Department of Surgery, King Khalid University Hospital, King Saud University, Riyadh, Saudi Arabia

Correspondence Address:
O Ibraheim
Consultant in Department of Anesthesia &ICU, College of Medicine, King Saud University, P.O.Box 7805, Riyadh 11472
Saudi Arabia
Login to access the Email id

Source of Support: None, Conflict of Interest: None


Rights and PermissionsRights and Permissions
Date of Web Publication5-Oct-2009
 

   Abstract 

Early and uneventful postoperative recovery of morbidly obese patients remains a challenge for anesthesiologists.However, it could be even more valuable to titrate the administration of inhaled anesthetic such as sevoflurane in morbid obese patients, to shorten emergence using bispectral index (BIS) monitoring. It would be a great advantage if BIS permitted a more rapid recovery and less consumption in morbidly obese patients with a high cost inhaled agent. The aim of the study is to show whether the titration of sevoflurane based on the BIS monitoring would allow shortening of recovery time in morbidly obese patients and to evaluate whether BIS monitoring would contribute to reduce the amount of sevoflurane administered while providing an adequate anesthesia.
Patients and Methods . Thirty morbidly obese ASA I&II patients undergoing laparoscopic gastric banding (LAGB) procedures were studied. In the first group (15 patients), patients were anaesthetized without the use of BIS (non BIS) group, and sevoflurane being administered according to standard clinical practice (control group). Second group, sevoflurane was titrated to maintain a BIS value between 40 and 60 during surgery, and then 60-70 during 15 min prior to the end of surgery (BIS group). Recovery times were recorded. Time to extubation was also noted, as well as the time to achieve a modified Aldrete score of 9 were evaluated subsequently at 10-min intervals until 3 h after surgery by nurses who had no knowledge of the study. Sevoflurane consumption was calculated using the vaporizer weighing method.
Results. Awakening and extubation times were significantly shorter in the BIS group (P<0.05). In the BIS (vs. non BIS) group, there were no significant differences observed in the time to obtain an Aldrete score of 9. The Sevoflurane consumption and cost in the BIS group were lower than in the non BIS group (P < 0.05).
Conclusion. Bispectral index monitoring during anesthesia for morbidly obese patients provides statistically significant reduction in recovery times. It also added advantage in decreasing sevoflurane consumption.

Keywords: Bispectral index, Morbid Obesity, Sevoflurane consumption


How to cite this article:
Ibraheim O, AlShaer A, Mazen K, Eldawlatly A, Turkistani A, Alkathery K, Al-Zahrani T, Al-Dohayan A, Bukhari A. Effect of Bispectral index (BIS) monitoring on postoperative recovery and Sevoflurane consumption among morbidly obese patients undergoing laparoscopic gastric banding. Saudi J Anaesth 2007;1:8

How to cite this URL:
Ibraheim O, AlShaer A, Mazen K, Eldawlatly A, Turkistani A, Alkathery K, Al-Zahrani T, Al-Dohayan A, Bukhari A. Effect of Bispectral index (BIS) monitoring on postoperative recovery and Sevoflurane consumption among morbidly obese patients undergoing laparoscopic gastric banding. Saudi J Anaesth [serial online] 2007 [cited 2020 May 27];1:8. Available from: http://www.saudija.org/text.asp?2007/1/1/8/56266

Obesity is a leading cause of preventable death in the United States, resulting in >100,000 excess deaths per year [1] and an estimated annual cost of $70 billion, accounting for nearly 10% of national health care expenditures [2] . The numerical growth of the obese population has been matched by an increase in the number of obese patients requiring hospitalization, bariatric procedures and intensive care unit (ICU) care [3],[4] this, in part, reflects the increasing prevalence of obesity in the world [5] . Morbid obesity has been identified as a risk factor for difficult mask ventilation, difficult laryngoscopy [6],[7] , and more frequent perioperative respiratory events [8],[9] . Traditionally, obesity has been seen as a physiologic state that magnifies the importance of the fat-blood solubility coefficient of the anesthetic in its relation to emergence and recovery; so early and uneventful postoperative recovery of morbidly obese patients remains a challenge for anesthesiologists. Bispectral index monitoring allows reduction in the total amount of anesthetic that patients are exposed to and appears to decrease time for emergence and recovery [11],[12]. However, it could be even more valuable to titrate the administration of some inhaled anesthetic such as sevoflurane in morbid obese patients, the hypothesis being to shorten emergence from sevoflurane anesthesia by using BIS monitoring. It would be a great advantage if BIS permitted a more rapid recovery and less consumption in morbidly obese patients with a high cost inhaled agent. No studies have investigated the potential usefulness of BIS monitoring to guide the administration of sevoflurane in morbid obese patient. In a randomized prospective controlled design, the present study evaluated and compared a BIS-monitored and a non-BIS-monitored anesthesia among morbidly obese patients undergoing laparoscopic gastric banding , to show whether the titration of sevoflurane based on the BIS monitoring would allow shortening of recovery time. The secondary objective to show whether BIS monitoring would contribute to reduce the amount of sevoflurane administered while providing an adequate anesthesia.


   Patients & Methods Top


After institutional review board approval, thirty morbidly obese (BMI >35 kg/m2), ASA I&II patients undergoing gastric banding procedures were studied Exclusion criteria were renal, hepatic or neurological dysfunction or use of benzodiazepines, anticonvulsants, alcohol, opioids or other psychotropic drugs. Patients randomly assigned to two groups; in the first group, patients were anaesthetized without the use of BIS (non BIS) group, and sevoflurane being administered according to standard clinical practice (control group). In a second group, sevoflurane was titrated to maintain a BIS value between 40 and 60 during surgery, and then 60-70 during 15 min prior to the end of surgery (BIS group). Recovery times were defined from the end of surgery: Time to awakening (i.e., medications were dosed to ideal body weight; no sedative premedication was administered prior to surgery. opening eyes on verbal command) was assessed at 1-min intervals in the operative room by the anesthetist. Time to extubation was also noted, as well as the time to achieve a modified Aldrete score of 9 were evaluated subsequently at 10-min intervals until 3 h after surgery by nurses who had no knowledge of the study. Sevoflurane consumption will be calculated using the vaporizer weighing method. Intravenous and included induction with fentanyl 2 ug/kg, propofol 1.5 to 2.0 mg/kg, and succinylcholine 1.00 to 1.5 mg/kg. Bispectral index monitoring (BIS A-2000 software 2.21, Aspect Medical Systems, Newton, and Mass) was initiated at induction, and smoothing time was 30 seconds. Standard monitoring (oxygen saturation [SpO2], electrocardiogram, end-tidal carbon dioxide [ETCO2], indirect or direct blood pressure (BP), and esophageal temperature probe) was used in all patients. Sevoflurane (2%) in 2 L/min fresh gas flow, mixed in air and oxygen, was administered to all patients for 5 min after endotracheal intubation and until skin incision the concentrations were then changed every 5 min as follows. Group BIS: the anesthesiologist had access to the monitor and adjusted the concentration of sevoflurane to achieve a target BIS in the range 40-60. However, in the control group, the anesthesiologist adjusted the sevoflurane concentration purely according to the clinical signs. During operation, the patients in both groups were observed for signs of inadequate anesthesia [Table 1]. Significant hypotension or bradycardia was defined as 20% reduction of the baseline figures. Any instances of inadequate anesthesia were managed by increasing the concentration of sevoflurane. Atracurium neuromuscular blockade was maintained to a single twitch of the train of four, During the last 15 minutes of the case, the BIS value was gradually titrated to 60 -70 by decreasing the inhaled anesthetic concentration. Intravenous fentanyl 100 ug was used approximately 15 minutes before the end of surgery to control early postoperative pain. Just before skin closure and before application of surgical dressing, neuromuscular blockade was reversed with neostigmine (0.07 mg/kg) and glycopyrolate (0.015 mg/kg). Fresh gas flows were increased to 10 L/min and the anesthetic was discontinued after dressing application. Mechanical ventilation (10 mL/kg ideal body weight) was continued until the first spontaneous respiration began, followed by assisted manual ventilation. A verbal command to open your eyes was given every 10 seconds. After a train-of-four ratio higher than 0.9, a 5-second head lift was performed and patients were extubated. Blinded study personnel recorded the time from discontinuation of the anesthetic gas to eye opening and extubation. After extubation, patients were transferred to the post-anesthetic care unit (PACU). In the PACU the time to achieve a modified Aldrete score of 9 was evaluated subsequently at 10-min intervals until 3 h after surgery by nurses who had no knowledge of the study. Postoperative pain was evaluated at 5-min intervals using a 5-point verbal rating scale (0: no pain; 1: light pain; 2: moderate pain; 3: intense pain; 4: severe pain). Pain scores were treated with Ketoprofen 100 mg IM. At the time of discharge from the recovery room and 24 hours after surgery patients were asked whether they dreaming or recalled any intraoperative events.

Sevoflurane consumption

For anesthetic consumption determination, we filled and weighed the sevoflurane vaporizer before induction. When anesthesia was complete, we disconnected and reweighed the vaporizer. This method has already been described by other authors [13],[14] . Inhaled anesthetic consumption was expressed in g/min and assessed for each patient, Conversion from grams to milliliters was performed by using the specific weights of the volatile anesthetic (sevoflurane1.52g/mL), then we calculated the mean value of each group and the difference between the two means in ml /h. Results were statistically evaluated using Student's t-test (significance P<0.05).

Statistics

Data will be collected a statistically analyzed using SPSS package (version 11.0, Washington) will be used. One-way repeated-measures analysis of variance (ANOVA) with post hoc Bonferroni correction was used to assess differences in mean between groups in respect of specific intraoperative events. The two-sample unpaired Student's t-tests were used to compare continuous variables: HR, MAP, duration of anesthesia, recovery times, and sevoflurane consumption. Data are expressed as mean values± SD. P values < 0.05 were considered statistically significant.


   Results Top


Thirty morbidly obese patients were enrolled in this study (n ∇ 15 in each group). The two groups were similar regarding age height weight; BMI and duration of anesthesia as shown in [Table 2].There were no statistical differences in intraoperative mean heart rate, mean blood pressure in either group. The time to awakening and extubation were shorter in the BIS group; time from the end of the operation to the time of response to verbal command ; nonBIS group: 8.66 ± 2.69 min; BIS group: 6.80 ± 2.14 min (P<0.05), and extubation time : non BIS group: 11.80 ± 2.9 min ; BIS: 9.26 ± 2.01 min (P<0.05). In the BIS (vs. non BIS) group, there were no significant differences observed in the time to obtain an Aldrete score of 9. The sevoflurane consumption and cost in the BIS group were lower than in the non BIS group (P < 0.05). The mean ± SD for the consumption per hour of sevoflurane in non BIS was 19.60 ± 3.94 ml liquid and 15.66 ± 4.04 ml liquid in BIS group [Table 2]. There was no recall or dreaming reported by any patient in recovery room or 24 hours after surgery in both groups. All patients were completely awake during the three postoperative hours without complications


   Discussion Top


The hypothesis of the present study was that sevoflurane titration guided by BIS monitoring could be particularly useful at the end of surgery to adapt sevoflurane delivery to a higher BIS level in order to ensure a faster recovery. We demonstrated that the addition of BIS to standard monitoring was associated with a slight but significant decrease in sevoflurane consumption. Also; there was a significant difference in recovery times when comparing BIS guided and standard monitoring anesthesia. These results are comparable to those reported in other studies that assessed titration of propofol [15] , desflurane or sevoflurane [16],[17] by using BIS monitoring but not in morbidly obese patients. Bispectral index monitoring allows reduction in the total amount of anesthetic that patients are exposed to and appears to decrease time for emergence and recovery [11],[12],[13],[14],[15],[16],[17],[18] . In the present study, the protocol designed as a single blinded comparison of the anesthetic administration; as sevoflurane was titrated intraoperatively against objective measures such as BIS, HR, MAP, and patient movements. Early recovery in the operative room (time to awakening and to extubation) was assessed by another anesthesia provider, which may not constitute an investigator associated bias. In addition, in the PACU, the nursing staff had no knowledge of the study. Furthermore, all anesthesia providers were anesthetists in our department and had experience of more than 5 years in anesthesiology. Bispectral index monitoring has been incorporated into studies comparing emergence and recovery profiles of desflurane and sevoflurane, mixed with nitrous, in elderly patients [19] and was incorporated into the study of De Baerdemaeker et al [20] . These studies all demonstrate that the time to recovery is shortened compared with previous non-BIS-guided studies where the dosage of desflurane or sevoflurane was based on MAC and hemodynamic response, whether mixed with nitrous oxide [21] or not. [22]

We agree with the contention that a rapid emergence from anesthesia with minimal respiratory and cardiovascular adverse effects is important in MO patients who have a high prevalence of cardiovascular disease and are at risk for respiratory complications.

White et al. [23] found that AEP and bispectral index (BIS) monitoring can decrease the end-tidal desflurane concentration during maintenance of anesthesia and discharge times after the end of anesthesia. During laparoscopic surgery, Recart et al. [24] found that AEP monitoring can reduce the desflurane requirement by 26%.

It has been shown that excessive costs can be minimized without compromising clinical outcome and patient satisfaction. Comparing anesthesia costs is not a trivial matter: two studies published in 1999 investigated outpatients anaesthetized with propofol and/or sevoflurane [25] : Tang and colleagues [26] focussed on the total costs required to achieve complete patient satisfaction and found that propofol/propofol-N2O were the cheapest kind of anesthesia, followed by propofol/sevoflurane-N2O and sevoflurane /sevoflurane-N2O. The present study showed that the use of BIS guided sevoflurane for the maintenance of anesthesia in morbidly obese patients was less expensive than maintenance of sevoflurane without BIS.

We have demonstrated that the addition of BIS to standard monitoring was associated with a slight, significant, decrease in sevoflurane consumption. Yll-Hankala and colleagues found that the sevoflurane saving was 40% in gynaecological surgery patients who also received opioids [27] . Subsequently, other authors [28] using isoflurane found similar findings to those reported here; in that study, there was a 12% saving in isoflurane consumption when using BIS which was explained as a result of the use of sufentanil and nitrous oxide [28] Pavlin and colleagues found, in a study of junior residents who had differing durations of training, that a modest reduction of anesthetic use was associated with greater experience (13%) [29] . for junior residents, the difference in the concentrations of volatile anesthetic administered to the BIS and control groups was quite remarkable. There was not much difference in the case of residents whose experience was >1 yr. In our study, our anesthetist had at least 5 or more years experience; in evaluating the values of BIS and control groups, experience of anesthesia is an important factor.

Anesthesia costs during surgery constituted only 5.6% of the total hospital costs. Many opportunities may be found to reduce costs in operating suites [30],[31] . A fast recovery is important after surgery. In our study, patient assessment in recovery was conducted by a 'blinded' PACU nurses. There were significant differences in the 'time to open eyes on verbal command', the 'time to motor responds on verbal command' between BIS and control group while no difference in Aldrete's score. This in accordance with Song and colleagues who found that the duration of stay in the recovery unit did not differ [11] ; Guignard and colleagues also reported that the Aldrete's scores were also similar [28] . Pavlin and colleagues also reported that BIS monitoring did not influence the duration of recovery [29] .

In conclusion, the recovery variables were shorter with BIS monitoring. Also we found that BIS monitoring made a significant savings in sevoflurane consumption and influenced the speed of recovery after laparoscopic gastric banding in morbidly obese patients.[31]

 
   References Top

1.Flegal KM, Graubard BI, Williamson DF, et al: Excess deaths associated with underweight, overweight, and obesity. JAMA 2005; 293:1861-1867   Back to cited text no. 1      
2. Colditz GA: Economic costs of obesity and inactivity. Med Sci Sports Exerc 1999; 31: S663-S667  Back to cited text no. 2      
3.Schirmer B, Watts SH: Laparoscopic bariatric surgery. Surg Endosc 2004; 18:1875-1878  Back to cited text no. 3      
4.Trus TL, Pope GD, Finlayson SR: National trends in utilization and outcomes of bariatric surgery. Surg Endosc 2005; 19: 616 - 620  Back to cited text no. 4      
5.Bjfrntorp P. Obesity. Lancet 1997; 350:423 - 6.  Back to cited text no. 5      
6.Juvin P, Lavaut E, Dupont H, et al. Difficult tracheal intubation is more common in obese than in lean patients. Anesth Analg 2003; 97: 595- 600.  Back to cited text no. 6      
7.Rose DK, Cohen MM. The airway: problems and predictions in 18,500 patients. Can J Anaesth 1994; 41:372 - 83.  Back to cited text no. 7      
8.Chung F, Mezei G. Adverse outcomes in ambulatory anesthesia. Can J Anaesth 1999; 46:R18-R34.  Back to cited text no. 8      
9.Pelosi P, Croci M, Ravagnan I, et al. The effects of body mass on lung volumes, respiratory mechanics, and gas exchange during general anesthesia. Anesth Analg 1998; 87:654 - 60.  Back to cited text no. 9      
10.Fisher A, Waterhouse TD, Adams AP. Obesity: its relation to anaesthesia. Anaesthesia 1975; 30:633- 47.  Back to cited text no. 10      
11.Song D, Joshi GP, White PF. Titration of volatile anesthetics using bispectral index facilitates recovery after ambulatory anesthesia. Anesthesiology 1997; 87:842- 8.  Back to cited text no. 11      
12.Guignard B, Coste C, Menigaux C, Chauvin M. Reduced isoflurane consumption with bispectral index monitoring Acta Anaesthesiol Scand 2001;45:308- 14.  Back to cited text no. 12      
13.Ma͸a͸tta͸nen H, Anderson R, Uusijarvi J, Jakobsson J. Auditory evoked potential monitoring with the AAITM-index during spinal surgery: decreased desflurane consumption. Acta Anaesthesiol Scand 2002; 46: 882-6.  Back to cited text no. 13      
14.Assareh H, Anderson RE, Uusijarvi J, Jakobsson J. Sevoflurane requirements during ambulatory surgery: a clinical study with and without AEP-index guidance. Acta Anaesthesiol Scand 2002; 46: 495-9  Back to cited text no. 14      
15.Gan TJ, Glass PS, Windsor A, Payne F, Rosow C, Sebel P et al. and the BIS utility Study Group. Bispectral index monitoring allows faster emergence and improved recovery from propofol, alfentanil, and nitrous oxide anesthesia. Anesthesiology 1997; 87: 808-815.  Back to cited text no. 15      
16.Song D, Joshi GP, White PF. Titration of volatile anesthetics using bispectral index facilitates recovery after ambulatory anesthesia. Anesthesiology 1997 ; 87: 842-848.  Back to cited text no. 16      
17.Yli-Hankala A, Vakkuri A, Annila P, Korttila K. EEG bispectral index monitoring in sevoflurane or propofol anaesthesia: analysis of direct costs and immediate recovery. Acta Anaesthesiol Scand 1999;43: 543-549.  Back to cited text no. 17      
18.Guignard B, Coste C, Menigaux C, Chauvin M. Reduced isoflurane consumption with bispectral index monitoring. Acta Anaesthesiol Scand 2001;45:308- 14  Back to cited text no. 18      
19.Heavner JE, Kaye AD, Lin BK, King T. Recovery of elderly patients from two or more hours of desflurane or sevoflurane anaesthesia. Br J Anaesth 2003; 91:502- 6.  Back to cited text no. 19      
20.De Baerdemaeker LE, Struys MM, Jacobs S, et al. Optimization of desflurane administration in morbidly obese patients: a comparison with sevoflurane using and inhalation bolus technique. Br J Anaesth 2003; 91:638- 50.  Back to cited text no. 20      
21.Nathanson MH, Fredman B, Smith I, White PF. Sevoflurane versus desflurane for outpatient anesthesia: a comparison of maintenance and recovery profiles. Anesth Analg 1995; 81:1186- 90.  Back to cited text no. 21      
22.Naidu-Sjfsv7rd K, Sjfberg F, Gupta A. Anaesthesia for videoarthroscopy of the knee. A comparison between desflurane and sevoflurane. Acta Anaesthesiol Scand 1998; 42:464-71.  Back to cited text no. 22      
23.White PF, Ma H, Tang J, Wender RH, Sloninsky A, Kariger R et al. Does the use of electroencephalographic bispectral index or auditory evoked potential index monitoring facilitate recovery after desflurane anesthesia in the ambulatory setting? Anesthesiology 2004; 100: 811-7.  Back to cited text no. 23      
24.Recart A, White PF, Wang A, Gasanova I, Byerky S, Jones SB et al. Effect of auditory evoked potential index monitoring on anesthetic drug requirements and recovery profile after laparoscopic surgery. Anesthesiology 2003; 99: 813-8.  Back to cited text no. 24      
25.Smith I, Terhoeve PA, Hennart D, et al. A multicentre comparison of the costs of anaesthesia with sevoflurane or propofol. Br J Anaesth 1999; 83: 564-570  Back to cited text no. 25      
26.Tang J, Chen L, White PF, et al. Recovery profile, costs, and patient satisfaction with propofol and sevoflurane for fast-track office-based anesthesia. Anesthesiology 1999; 91: 253-261.  Back to cited text no. 26      
27.Yll-Hankala A, Vakkuri A, Annila P, Kortilla K. EEG bispectral index monitoring sevoflurane or propofol anaesthesia: analysis of direct costs and immediate recovery. Acta Anaesthesiol Scand 1999; 43: 545-549.  Back to cited text no. 27      
28.Guignard B, Coste C, Menigaux C, Chouvin M. Reduced isoflurane consumption with bispectral index monitoring. Acta Anaesthesiol Scand 2001; 45: 308-314.  Back to cited text no. 28      
29.Pavlin DJ, Hong Y, Freund PR, Koerschgen ME, Bower JO, Bowdle TA. The effect of bispectral index monitoring on end-tidal gas concentration and recovery duration after outpatient anesthesia. Anesth Analg 2001; 93: 613-619.  Back to cited text no. 29      
30.Watcha MF, White PF. Economics of anesthetic practice. Anesthesiology 1997; 86:1170-1196.  Back to cited text no. 30      
31.Johnstone RE, Martinec CC. Cost of anesthesia. Anesth Analg 1993; 76: 840-848.  Back to cited text no. 31      



 
 
    Tables

  [Table 1], [Table 2]



 

Top
 
Previous article Next article
 
  Search
 
    Similar in PUBMED
   Search Pubmed for
   Search in Google Scholar for
 Related articles
    Access Statistics
    Email Alert *
    Add to My List *
* Registration required (free)  

 
  IN THIS Article
    Abstract
    Patients & Methods
    Results
    Discussion
    References
    Article Tables

 Article Access Statistics
    Viewed1916    
    Printed183    
    Emailed7    
    PDF Downloaded0    
    Comments [Add]    

Recommend this journal