Unconscious State Clinical Trial
Official title:
The Effect of BIS Monitorization to Intraoperative Anesthetic and Analgesic Consumption During Coronary Artery Grafting Surgery and Postoperative Mortality and Morbidity
213 patients undergoing elective on-pump coronary artery bypass grafting (CABG) were enrolled into this prospective-clinical trial.After hundred and sixty three patients were excluded due to various reasons, 50 patients were randomized to BIS (bispectral index) and MAC (minimum alveolar concentration) groups. In BIS group (Group B, n=25), desflurane was titrated within 40 to 60 BIS values and in MAC group (Group M, n=25) within 0.7 to 1.3 MAC. Primary end point of the study was to investigate the difference of desflurane consumption between groups.
This study was approved by Baskent University Institutional Review Board and Ethics
Committee (Project No: KA13/294) and supported by Baskent University Research Fund. The
study was conducted in a single university hospital (Başkent University Hospital, Ankara,
Turkey). Between January 2014 and October 2014, 213 patients undergoing CABG surgery were
assessed for eligibility. 163 patients were excluded because of not meeting inclusion
criteria. 50 patients were enrolled into this prospective-clinical trial. All patients were
informed of the nature of the study and gave their written consent during preoperative visit
performed by the investigators.Diazepam 0.1 mg/kg (Diazem®) and famotidine HCI 40 mg
(Famodin®) were given by the oral route to all patients, the day before surgery at 11 pm and
midazolam 0.1 mg/kg (Dormicum®) was given to all patients by oral route 30 min before
starting anesthesia. After routine 5 lead electrocardiography, pulse oximeter monitoring and
peripheric venous and arterial cannulations, endotracheal intubation was performed. BIS
monitoring (BIS Quatro Sensor, Aspect Medical Systems, Inc, Norwood, MA, USA) was applied to
BIS group in accordance with the manufacturer's instructions. Anesthesia was induced with
propofol 1-2 mg/kg and fentanyl 5-7 mcg/kg by intravenous route, based on the patient's
physical status. Muscle relaxation was achieved using iv rocuronium 0.6 mg/kg. Desflurane
was administered through a calibrated vaporizer (D-Vapor, Drager Medical AG&Co. KG, Lübeck,
Germany) in both groups.
In BIS group (Grup B, n=25) desflurane was titrated to maintain a BIS value of 40 to 60.
Anesthesia was maintained with remifentanil 0.1-0.4 mcg/kg/min, and desflurane as a volatile
agent. In MAC group (Grup M, n=25) desflurane was titrated within 0.7 to 1.3 MAC. During
maintenance, all patients were assessed for hypotension (systolic artery pressure (SAP) <
20% from baseline), bradycardia (heart rate (HR) < 45 bpm) or signs of inadequate
anesthesia. Inadequate anesthesia was defined as hypertension (SAP >20% from baseline),
tachycardia (HR > 100 bpm) or patient movement, eye opening, swallowing, grimacing,
lacrimation or sweating. In MAC group, if anesthesia was inadequate, the desflurane
concentration was increased in steps of 0.5 vol % as necessary. In BIS group desflurane was
titrated for BIS values between 40 and 60. If this was judged insufficient, the infusion
rate of remifentanil was increased by 0.05 g/kg/min. Hemodynamic parameters were maintained
within 20% of the basal values with dopamine and nitroglycerin, as required. Dopamine was
administered 2-20 mcg/kg/min by central venous route. Calcium and noradrenaline were used as
iv boluses if needed. All patients were given fluid infusions to maintain central venous
pressure between 10-15 mmHg. Hypotension was initially treated with 100-250 mL iv fluid
boluses; desflurane concentration was then reduced in steps of 0.5 vol % and finally, an iv
vasopressor (dopamine, adrenaline, dobutamine) was given at a dose chosen by the
practitioners. Bradycardia was treated with 0.5 mg atropine. Practitioners were reminded of
this protocol via a visual protocol in the room. Morphine 0.1 mg/kg was given all of the
patients for pain control. The amount of desflurane administered from the start of the
anesthesia to the end of surgical procedure was calculated in two groups. The amount of
desflurane administered during the procedure was calculated by using the formula below:
Consumption of anesthetic agent in ml/hr = 3 X set concentration % X fresh gas flow
L/min.Patient characteristics and surgical variables such as intraoperative blood loss,
anesthesia and surgery durations, BIS (bispectral index) and MAC (minimum alveolar
concentration) values, intraoperative hemodynamic parameters and drug requirements of
patients, amounts of fluid and blood administered, CVP, urine output, features of the
surgery were documented by research staff. All patients were transferred to the ICU.
Applying an a priory power analysis, 24 patients at least had to be enrolled in each group
to detect a reduction of 20% at least in desflurane consumption with a risk of a of 0.05 and
a statistical power of 0.8. Vanderbilt University power and sample size calculation program
had been used for power analysis.
Data are presented as medians (interquantile ranges), percentages, or number of cases.
Continuous data were compared by Mann-Whitney tests. Categorical data were compared with
ki-square test. Significance was defined by P values less than 0.05 using a two-tailed test.
Data analysis was performed using IBM-SPSS version 20.0 (IBM-SPSS Science Inc., Chicago,
IL). Demographic features, intraoperative use of propofol, intraoperative hourly and total
amounts of remifentanil, fentanyl, muscle relaxant and morphine, hourly desflurane
consumption, hemodynamic parameters, duration of surgery, aortic cross-clamp and
cardiopulmonary bypass (CPB) times, defibrillation and pacemaker requirements, maximum
positive inotropic and vasodilator drug requirements, amount of intraoperative fluids, blood
and blood products used, urine outputs at the end of the surgery and central venous pressure
(CVP) values, intraoperative arterial blood gas results were recorded.Durations of
intubation, mechanical ventilation, lengths of ICU and hospital stay, 28 days mortality and
postoperative complications were also recorded.
;
Allocation: Randomized, Intervention Model: Parallel Assignment, Masking: Open Label, Primary Purpose: Health Services Research
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