Dexmedetomidine for attenuating haemodynamic response to intubation stimuli in morbidly obese patients anaesthetised using low-opioid technique: comparison with fentanyl-based general anaesthesia.

BACKGROUND: Anaesthesiologists are facing the problem of an increasing population of morbidly obese patients. In order to minimize the risk of opioid-induced postoperative respiratory failure, the intraoperative administration of opioids should be reduced or replaced with other drugs. The purpose of this study was to compare haemodynamic response elicited by intubation in morbidly obese patients between two variants of anaesthesia induction: fentanylbased or low-opioid using dexmedetomidine.

METHODS: Forty-two morbidly obese patients scheduled for bariatric surgery were randomly assigned to two groups: low-opioid using dexmedetomidine (DEX) or fentanyl-based (FNT) anaesthesia. Patients were premedicated with 100 μg of fentanyl i.v. In the DEX group, a 10 minute infusion of a loading dose of 200 μg of dexmedetomidine was started. In the FNT group, 2 mg of intravenous midazolam was given. Thereafter, propofol was used in both groups. In the FNT group, patients received a dose of fentanyl up to 5 μg kg⁻¹ of ideal body weight. Following administration of rocuronium, laryngoscopy and tracheal intubation were performed. Haemodynamic parameters, including systolic (SBP), diastolic (DBP) and mean arterial (MAP) blood pressure, as well as heart rate (HR), were recorded before and after intubation. Patients who were not intubated at first attempt were excluded from the study.

RESULTS: Data from 33 patients were analysed. There were no statistically significant differences between the DEX and FNT groups regarding demographic data. Haemodynamic response to intubation was defined as mean change (d) in values of analysed parameters that occurred during intubation. The following differences were observed: dSBP FNT +11.6 mm Hg vs. DEX +0.4 mm Hg (P = 0.15); dDBP FNT +3.7 mm Hg vs. DEX +3.5 mm Hg (P = 0.98); dMAP FNT +8.6 mm Hg vs. DEX +1.4 mm Hg (P = 0.36); dHR FNT +2 beats min-1 vs. DEX -1 beat min⁻¹ (P = 0.30). None of these comparisons yielded significant differences.

CONCLUSIONS: The study revealed no advantage of fentanyl over low opioid dexmedetomidine-based induction of general anaesthesia in attenuating cardiovascular response to intubation in morbidly obese patients.