Apnoea and unconsciousness after apparent recovery from alfentanil-supplemented anaesthesia

Several cases of recurrent respiratory depression progressing to apnoea and unconsciousness after apparent recovery from sufentanil have been reported recently. Alfentanil has the shortest elimination half-time of the narcotics used in anaesthesia, suggesting that it should be the least likely to cause postoperative respiratory depression. A case of recurrent unconsciousness and respiratory arrest after apparent recovery from alfentanil-isoflurane-nitrous oxide anaesthesia is reported. A total dose of 137 micrograms.kg-1 alfentanil was given over a 3.25-hr period to a 45-year-old female undergoing partial gastrectomy. Naloxone, 0.16 mg IV, rapidly restored spontaneous ventilation and consciousness. This case demonstrates that apnoea and unconsciousness can also recur after apparent recovery from alfentanil. Recovery room personnel should be aware of this phenomenon. Earlier detection may permit treatment before apnoea occurs. Patients given narcotic-supplemented anaesthesia should be monitored by capnography and/or pulse oximetry in the early postoperative period.

Comparison of non-invasive respiratory and arterial blood gas analysis. A recovery room study on acute respiratory depression

The effect on invasive and non-invasive oxygen, carbon dioxide and haemoglobin saturation measures of two repeated doses of alfentanil 0.5 microgram/kg were tested in 16 patients scheduled for elective cataract surgery under periocular anaesthesia. Alfentanil caused an acute respiratory depression, which was demonstrated as increased levels of arterial and end-tidal carbon dioxide and concomitant decrease in arterial and end-tidal oxygen levels as well as decreased arterial blood saturation and pulse oximeter readings. There was a good correlation between the non-invasive respiratory parameters and blood gas levels, as well as between pulse oximetry numbers and oxygen saturation of arterial blood. Therefore, hypoventilation and concurrent hypoxaemia can be predicted by monitoring end-tidal CO2.

Seizures during opioid anesthetic induction--are they opioid-induced rigidity?

The tape recorded EEGs of 127 patients anesthetized with large doses of opioids were retrospectively analyzed for evidence of opioid-induced seizures, and in particular, correlated with movements that occurred during induction and could be clinically interpreted as seizures. Bilateral EEG leads in patients receiving fentanyl (20), sufentanil (20), or alfentanil (87) were recorded. Forty-six of these patients from all opioid groups manifested intense rigidity, as assessed both clinically and by EMGs recorded from eight muscles in 69 of the patients receiving alfentanil. This intense rigidity often resembled seizures, in that the phenomenon entailed severe stiffness of both limbs and trunk, with an explosive onset of myoclonic limb movements, and associated vertical nystagmus. Electroencephalographic observations were extensive, entailing 69 h of paper recordings played back from the tapes, at paper speeds of 30 or 60 mm/s, with detailed annotations from the voice track. These paper recordings were examined in detail independently by three of the investigators, who were unaware of the clinical phenomena that had occurred. The only observed EEG activity that could have been interpreted as epileptiform consisted of small sharp waves related to muscle activity or other artifact. The EEG never indicated seizure activity during these drug-induced movements and rigidity. Reports of opioid-induced seizures are reviewed and a set of criteria is offered to help achieve future consistency and credibility in evaluating this phenomenon. The available evidence does not support the existence of opioid-induced seizures in the clinical setting.

Alcohol consumption alters the pharmacodynamics of alfentanil

Two groups of women, ASA physical status 1, undergoing surgery for primary breast cancer, were studied to assess the effect of alcohol intake on alfentanil pharmacodynamics. Patients in group 1 (n = 6) had an average daily consumption of 20-40 g alcohol. Patients in group 2 (n = 8) were life-long abstainers or drank only occasionally (less than 60 g per year). Anesthesia was induced and maintained with 66% N2O in O2 and alfentanil. Alfentanil was administered by a computer-controlled infusion pump. If during surgery the patient exhibited somatic, hemodynamic, or other autonomic signs of inadequate anesthesia (response), the target alfentanil plasma concentration was increased by 50-100 ng/ml. If there was no response during a 15-min period, the target concentration was decreased by 50-100 ng/ml. Arterial blood samples were taken before any change of the target concentration, 4 min after a new predicted target concentration was achieved, and at extubation. Plasma concentrations were determined by capillary gas chromatography. Alfentanil protein binding was measured by equilibrium dialysis. Plasma alfentanil concentration-effect data were analyzed by nonlinear regression, where effect was either response or no response to surgical stimuli. The average total alfentanil requirement was significantly (P less than 0.005) higher in group 1 (3.7 +/- 1.2 micrograms.kg-1.min-1) than in group 2 (1.9 +/- 0.4 micrograms.kg-1.min-1). The average Cp50 (the plasma concentration for which the probability of no response during surgery is 50%) was significantly (P less than 0.001) higher in group 1 (522 +/- 104 ng/ml) than in group 2 (208 +/- 26 ng/ml).(ABSTRACT TRUNCATED AT 250 WORDS)

Alfentanil for general anesthesia in oral and maxillofacial surgery

This study evaluated alfentanil (Alfenta, Janssen Pharmaceutica, Piscataway, NJ) as an analgesic supplement to oxygen/nitrous oxide anesthesia for outpatient oral and maxillofacial surgical procedures. Fifty American Society of Anesthesiology (ASA) class I and II patients were induced and maintained with an established regimen. Parameters measured included anesthetic properties, orientation time, recovery time, and presence of side effects. The results indicated that alfentanil provides acceptable anesthesia with minimal recovery time, but occasional side effects such as nausea and vomiting occurred postoperatively. This drug, when properly used, is a welcome addition to other established general anesthetic agents in oral and maxillofacial surgery.

[Muscular rigidity caused by alfentanil: prevention]

We studied three groups of 30 patients each, undergoing minor orthopaedic surgery, anaesthetized with alfentanil (30 micrograms/kg bolus followed by an infusion of 0.3 micrograms/kg/min), thiopental 3 mg/kg and 70% N2O via facial mask. Patients in group I were treated, three minutes before induction, with vecuronium 0.02 mg/kg i.v., while those in group II were premedicated with diazepam 0.15 mg/kg i.m. 30-45 minutes before induction. Group III served as control. Muscular rigidity was evaluated clinically with a subjective score based on a scale of 0 (no rigidity) to 3 (severe rigidity). Diazepam did not give significant protection from muscular rigidity. Vecuronium administration did not significantly reduced the number of patients who became rigid, but significantly decreased the incidence of severe rigidity (p less than 0.005), the mean rigidity score (p less than 0.05) and the incidence of rigidity at the induction of anaesthesia (p less than 0.0005). We also observed a progressively increasing incidence of rigidity with increasing age (not significantly) and body weight (p less than 0.05 total rigidity, p less than 0.01 severe rigidity).

Sufentanil and alfentanil pattern of consumption during patient-controlled analgesia: a comparison with morphine

Pattern of drug consumption and side effects of sufentanil and alfentanil were compared to morphine, using "on-demand" patient-controlled analgesia (PCA). After a non-narcotic general anesthetic, a bolus dose of the narcotic was given intravenously towards the end of surgery. PCA was started in the recovery room. Data were retrieved postoperatively for a total of 24 h. Results showed a wide range of pattern of drug consumption and uniform acceptance of therapy by the nurses and the patients in all the groups. The frequency of use of incremental doses was greater than 2-2.5-fold for the sufentanil and alfentanil groups, respectively, compared with morphine. The bolus dose of the narcotics failed to achieve adequate analgesia for 2 h for morphine and sufentanil and for 6 h for alfentanil. Overall patients were most sedated with morphine and least sedated with sufentanil. At the time intervals sampled, there was a higher incidence of oxygen desaturation--less less than 95% with morphine and alfentanil, compared with sufentanil. There was a similar incidence of nausea in all the groups. Further study is needed to determine precisely the best dose regimens for sufentanil and alfentanil, especially in reference to optimum loading doses. Sufentanil appears to be a promising drug for PCA use.