Low-dose ketamine failed to spare morphine after a remifentanil-based anaesthesia for ear, nose and throat surgery.

BACKGROUND: Ketamine has been claimed to prevent acute opioid tolerance and hyperalgesia following acute exposure to opioids and its use has been proposed to decrease postoperative morphine consumption. METHODS: We conducted a randomized, double-blind, controlled study to evaluate the effect of intravenous (i.v.) ketamine on postoperative pain for 48 h after major ear, nose and throat (ENT) surgery. Thirty-one patients received i.v. ketamine 0.15 mg kg(-1) before induction and 2 microg kg(-1) min(-1) during anaesthesia, and 31 patients were administered placebo in a similar manner. Anaesthesia was standardized with remifentanil and propofol, but without nitrous oxide. Standardized postoperative analgesia included paracetamol, methylprednisolone and morphine administered via a patient controlled analgesia (PCA) device. RESULTS: Intra-operative remifentanil consumption was not different between the ketamine group (0.25 +/- 0.07 microg kg(-1) min(-1)) and the control group (0.22 +/- 0.07 microg kg(-1) min(-1)). In the postoperative period, both groups experienced an identical pain course evolution. Cumulative morphine consumption was not significantly different between groups: at 24 h it was 33.3 +/- 14.9 with ketamine and 31.9 +/- 15.3 mg in controls, at 48h it was 40.4 +/- 20.6 mg with ketamine and 42.5 +/- 25.9 mg in controls. CONCLUSION: Low-dose ketamine added to a remifentanil-based propofol anaesthesia did not reduce morphine consumption after major ENT surgery.

Myocardial effects of isoflurane in healthy infants and small children. Assessment by continuous oesophageal aortic blood flow echo-Doppler.

BACKGROUND: In paediatric healthy patients and in real peroperative conditions, the cardiovascular effects of isoflurane have been poorly described. METHODS: We have evaluated the myocardial effects of 1% end-expired concentration (EEC) of isoflurane in 25 healthy infants or small children undergoing superficial surgical therapy for small burns with a continuous aortic blood flow echo-Doppler device. Aortic blood flow (ABF) was measured with a small oesophageal probe specially designed for infants. The aortic flowmeter was connected with satellite devices to visualize the haemodynamic profile variations during the isoflurane inhalation period. RESULTS: Isoflurane significantly decreased ABF and increased pre-ejection period/left ventricular ejection time (PEP/LVET), when compared with control values previously recorded 5 min after induction with halothane-fentanyl and atracurium (respectively, 80 +/- 7%, mean +/- SD; P < 0.001 and 111 +/- 11%; P = 0.017, 5 min after EEC of isoflurane reached 1%, then respectively, 75 +/- 12%; P < 0.001 and 119 +/- 16%; P < 0.001, at the end of the isoflurane inhalation period). These variations reversed to a great extent when isoflurane was switched off (97 +/- 17% for ABF; P = 0.08 and 105 +/- 12% for PEP/LVET; P = 0.75). Among the usual parameters, 1% EEC of isoflurane caused no significant changes in heart rate, moderately decreased mean arterial pressure (successively, 88 +/- 12%; P = 0.045 and 87 +/- 19%; P = 0.049), but belatedly decreased end-tidal CO2 pressure (87 +/- 11% at the end of the inhalation period (P < 0.001) which persisted 5 min after isoflurane was turned off (90 +/- 11%; P < 0.001)). CONCLUSIONS: These findings suggest that isoflurane can transiently depress cardiac function in healthy infants.

The hemodynamic effects of pneumoperitoneum during laparoscopic surgery in healthy infants: assessment by continuous esophageal aortic blood flow echo-Doppler.

UNLABELLED: Cardiovascular changes due to pneumoperitoneum during laparoscopic surgery are established in adult patients, but not known in infants. We investigated the hemodynamic effects of laparoscopy during general anesthesia in 12 ASA physical status I infants by using noninvasive continuous esophageal aortic blood flow (ABF) echo-Doppler monitoring. During the laparoscopic procedure, intraabdominal pressure was maintained automatically at 10 mm Hg by a CO2 insufflator, and minute ventilation was adjusted to avoid hypercapnia. Hemodynamic changes were continuously recorded on soft magnetic support and assessed at three time intervals: t0 (after the initiation of anesthesia), t1 (5 min after peritoneal insufflation), and t2 (5 min after exsufflation). The induction of pneumoperitoneum resulted in a significant decrease in ABF and stroke volume, and in a significant increase in systemic vascular resistance, compared with control values: 67% +/- 9% (P < 0.001), 68% +/- 10% (P < 0.001), and 162% +/- 34% (P < 0.001), respectively. These changes were completely reversed after peritoneal exsufflation. Pneumoperitoneum caused no significant changes in mean arterial pressure or in end-tidal CO2 pressure. These findings demonstrate that laparoscopy is associated with hemodynamic changes without clinically deleterious consequences in healthy infants during a short duration of pneumoperitoneum. IMPLICATIONS: The peritoneal insufflation achieved during laparoscopic surgery is associated with cardiovascular impairments (decrease in cardiac performance and increase in vascular resistance). We found that these changes had no clinically deleterious effects in healthy infants.