Effects of remifentanil infusion bis-titrated on early recovery for obese outpatients undergoing laparoscopic cholecystectomy.

BACKGROUND: In obese patients functional residual capacity comes down with a possible hypoxemia in postoperative period. In fact many studies has been begun to determine optimum ventilation regulation and the best position for these patients, but the question has not been solved. As remifentanil can reduce of 50% the inhalatory anaesthetic request and reverse Trendelemburg position is extremely useful for these patients, we hypothesized that use of a continuous remifentanil infusion during balanced anaesthesia with sevoflurane, BIS-titrated, associated to reverse Trendelem-burg position could facilitate emergence from anaesthesia in obese patients undergoing laparascopic cholecystectomy. METHODS: We studied 40 patients, ASA II class, with higher than 30 kg/m2 body mass index, undergoing to laparoscopic cholecystectomy. All the patients, in operating room, received standard monitoring and BIS sensor application. All the data were continuously collected. Induction of anaesthesia has been with a refracted bolus in 120 sec of remifentanil 1 mg/kg, followed by propofol 1.5 mg/kg and cisatracurium 0.15 mg/kg. Maintenance of anaesthesia has been by balanced anaesthesia with continuous remifentanil infusion, ventilating patients with sevoflurane in oxygen and air. Patients were randomized into two homogenous groups. Into the control group has been varied sevoflurane inspiratory concentration on the ground of BIS value (from 0.3% to 3%), while into remifentanil group remifentanil infusion has been varied (from 0.25 to 2 mg/kg/min) to maintain medium pressure values which don't stray more than 25% from basal values, on the ground of BIS values. On pre-established times of operation, respiratory mechanics and blood gases were examined. RESULTS: As it was to expect, sevoflurane concentration variations resulted very high in control group compared to remifentanil group. Awakening time, extubation, orientation and transfer to PACU (postanaesthesia care unit) resulted significantly lower than remifentanil group. CONCLUSIONS: Concluding, remifentanil infusion, BIS-titrated, facilitates awakening times from balanced anaesthesia with Sevoflurane in obese patients, submitted to laparoscopic cholecystectomy.

Effects of sevoflurane versus propofol on QT interval.

BACKGROUND: Prolongation of the QT interval is an alteration of the electrocardiogram (ECG) that may result in a potentially dangerous polymorphic ventricular tachycardia known as torsade de pointes. Michaloudis et al. investigated the effect of isoflurane and halothane on the QT interval in premedicated and non premedicated children, and in premedicated adults. Isoflurane significantly prolonged the QTc interval, in contrast to halothane, which shortened the QTc interval. The aim of the study was to evaluate the effect of sevoflurane on the QT interval in patients undergoing non-cardiac surgery. METHODS: One hundred and eighty patients classified as ASA physical status I-III were enrolled and 102 were excluded. Patients had been scheduled for elective non cardiac surgery. Exclusions criteria were: cardiovascular impairment or chronic obstructive lung disease, medication affecting QT interval, and an abnormal prolongation of the QTc interval (440 ms). The patients were then randomly allocated to one of two groups, one receiving sevoflurane anesthesia and the other receiving propofol anesthesia. In all patients, a 12 lead ECG was recorded before surgery, after intubation, after extubation. The investigators reading the ECG were blinded to the type of induction and anesthesia used. The following variables were recorded or calculated: heart rate, P-R interval, QRS interval, QT interval, QTc interval according to Bazett's formula, systolic, diastolic and mean blood pressure. RESULTS: The sevoflurane significantly prolongs the QT and the QTc interval, whereas the induction and total intravenous anesthesia with propofol significantly shortens the QT but not the QTc interval. CONCLUSIONS: The amount the sevoflurane-associated QT prolongation may possibly be of clinical significance in some patients presenting long QT syndrome, hypokalemia, or in presence of other agents or factors that lengthen QT.

Airway management with the Combitube during anaesthesia and in an emergency.

The oesophageal-tracheal Combitube (Kendall-Sheridan Catheter Corp., Argyle, NY) is a device designed for difficult airways and emergency intubation. The manufacturer recommends that the Combitube size 37F SA be used in patients with a height of between 122 and 152 cm. The aim of this study was to evaluate whether ventilation is effective and reliable in anaesthetized patients taller than 152 cm using the size 37F SA in the oesophageal position. We also evaluated whether airway protection is adequate and whether direct intubation of the trachea with the Combitube inserted in the oesophagus is possible. We studied 15 adult patients undergoing routine general anaesthesia and 20 patients who required emergency intubation following trauma. They were between 150 and 180 cm in height. Under direct vision, a size 37F SA Combitube was inserted into the oesophagus of all the patients undergoing routine general anaesthesia (control group). Blind insertion was performed in the emergency patients (emergency group). The pharyngeal balloon was inflated with a volume titrated to air leak and cuff pressures were measured. During surgery, a laryngoscope was inserted into the pharynx with the pharyngeal balloon deflated and the laryngoscopic view was evaluated using the Cormack-Lehane scale. Ventilation was effective and reliable in all 35 patients who were between 150 and 180 cm in height. In addition, a direct relationship between the pharyngeal balloon volume and patient height was established (P<0.05), using linear regression models. The laryngoscopic view of the glottis was adequate to allow direct tracheal intubation in patients in the control group, so that the Combitube size 37F SA may be used in patients from 122 to 185 cm in height. The trachea could be directly intubated with the Combitube in the oesophageal position in patients with normal airways and in patients involved in trauma. In all patients in the emergency group, blind insertion of the Combitube resulted in the device being placed in the oesophagus. The airway protection appears to be adequate.

Bispectral index monitoring in sevoflurane and remifentanil anesthesia. Analysis of drugs management and immediate recovery.

BACKGROUND: Recent studies have suggested that electroencephalogram bispectral index (BIS) monitoring can improve recovery after anaesthesia and save money by shortening patients postoperative stay. The aim of the study is to evaluate the management of drugs and to measure immediate recovery after anaesthesia with or without BIS monitoring. METHODS: We studied 90 patients undergoing abdominal surgery randomly allocated to one of two groups of 45 each with or without BIS monitoring. Standard monitoring (EKG, arterial oxygen saturation and non-invasive blood pressure) was applied. All groups were monitored with BIS, using electrodes (Zipprep, Aspect Medical Systems) applied to the forehead. In the group 2 the BIS value was blinded to the anaesthesiologist. The BIS value was displayed using Spacelabs Medical BIS Ultraview Monitor. After obtaining baseline values for the BIS index (group 1) and haemodynamic data (all groups) anaesthesia was induced with a bolus dose of remifentanil and TPS, and vecuronium. The anaesthesia was maintained with Remifentanil and Sevoflurane. At standard times BIS, haemodynamic and respiratory parameters were recorded. Recovery times were measured by a study coordinator. Drug consumption was calculated. RESULTS: In group 1 the consumption of Sevoflurane decreased by 40 % while the consumption of remifentanil decreased by 10 % as compared to group 2. The use of vecuronium did not change in the 2 groups. In group 1 the time elapsed from cessation of anaesthetics to orientation decreased significantly. The difference was 5 min, from 11 to 6 min. CONCLUSIONS: BIS monitoring decrease both sevoflurane and remifentanil consumption, when compared to anaesthesia without BIS, with an immediate recovery after sevoflurane and remifentanil anaesthesia.

Control of haemodynamic response to tracheal intubation in cigarette smokers compared with non-smokers.

Some authors have demonstrated that a bolus dose of 1 microg/kg followed by an infusion rate of 0.5 microg/kg/min is adequate to attenuate the haemodynamic response to laringoscopy and tracheal intubation. In this study we have evaluated the efficacy of Remifentanil in controlling haemodynamic and some neuroendocrine responses to tracheal intubation in smokers compared with non-smokers. We studied 126 patients, ASA I-II, aged 20-49 yr, submitted laparoscopic cholecystectomy (66 male, 60 female); sixty-three patients were non-smokers and 63 patients smoked 10 or more cigarettes per day. Anaesthesia was induced with thiopental 3-5 mg/kg and remifentanil 1 microg/kg. Vecuronium 0.1 mg/kg was administrated to facilitate tracheal intubation. Immediately after intubation heart rate of smokers (mean 101.2 +/- 17 beat/min) was significantly higher (p < 0.001) than non-smokers (mean 90.2 +/- 14 beat/min) and also the neuroendocrine responses of smokers (epinephrine value 155 +/- 173 pcg/ml; norepinephrine value 276 +/- 164 pcg/ml) was significantly higher (p < 0.01) than non-smokers (epinephrine 95 +/- 75, norepinephrine 154 +/- 76). These findings may be clinically important to evaluate the risk of ischaemic heart diseases.

Efficacy of a single-dose ondansetron for preventing post-operative nausea and vomiting after laparoscopic cholecystectomy with sevoflurane and remifentanil infusion anaesthesia.

In this randomized study we compared the efficacy of ondansetron 4 mg with ondansetron 8 mg for the prevention of postoperative nausea and vomiting (PONV) after laparoscopic cholecystectomy with sevoflurane and remifentanil infusion anaesthesia. Sixty patients were randomized to receive ondansetron 8 mg (30 pts) or ondansetron 4 mg (30 pts) before the induction of anaesthesia with thiopental and remifentanil. Anaesthesia was maintained with sevoflurane (0.5 MAC), oxygen and remifentanil infusion (0.25, 0.35, 0.5 microg/kg/min). Postoperative analgesia was provided by intravenous ketorolac 60 mg. The incidence of PONV, the pain score, and the analgesic requirement were recorded for 24 hours. There was no difference among groups in patient characteristics, risk factors for PONV, or side effects. During the first 6 h postoperatively, the incidence of PONV after ondansetron 4 mg and 8 mg were similar (p < 0.001). After 6 h the incidence of PONV increased significantly in patients who had received ondansetron 4 mg (p = 0.01) and was greater than that in patients who had received ondansetron 8 mg (p = 0.001). We conclude that single-dose ondansetron 8 mg is more effective than ondansetron 4 mg in the prevention of PONV after laparoscopic cholecystectomy. This surgery is associated with a high incidence of postoperative nausea and vomiting. A single dose of IV ondansetron 8 mg is well tolerated and decrease the number of nausea and vomiting episodes after surgery.