Department of Anaesthesia, Hull Royal Infirmary, Anlaby Road, Hull HU3 2JZ, UK
Accepted for publication: May 18, 2000
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Abstract |
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Br J Anaesth 2000; 85: 623--5
Keywords: analgesics opioid, remifentanil; anaesthetics i.v., propofol; neuromuscular block, succinylcholine; intubation tracheal
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Introduction |
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Methods and results |
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Intravenous access was established, but no fluids were given. Mean arterial pressure (MAP), heart rate (HR), oxygen saturation and end-tidal carbon dioxide (FE'CO2) were monitored during induction using the Datex Cardiocap. Patients were not preoxygenated, but received oxygen from the end of a Bain system held 510 cm caudal to the chin. In group PS, propofol 2 mg kg1 was given over 60 s followed immediately by succinylcholine 1 mg kg1. In groups PR 2 and PR 4, propofol 2 mg kg1 was followed immediately by remifentanil 2 or 4 µg kg1, with each drug administered over 30 s. After induction, mask ventilation was initiated with 2% sevoflurane in 50% nitrous oxide in oxygen at a total flow of 8 litres min1 and continued in group PS until fasciculation had ceased, and for 30 s in both remifentanil groups. At this point an experienced, blinded anaesthetist took over airway control and attempted tracheal intubation of the patient. During laryngoscopy, each patient was assessed for five variables: jaw mobility; mask ventilation; vocal cord visibility; vocal cord position; and patient movement during intubation. The criteria used for ranking these variables are shown in Table 1.
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Data were analysed using one-way analysis of variance with Tukeys multiple comparisons (age, weight, duration of apnoea and MAP changes between groups), the paired t-test (MAP and HR changes within groups) and the KruskalWallis test with Dunns multiple comparisons (intubation scores). A value of P<0.05 was considered statistically significant.
We studied 17 patients in group PS, 20 in group PR 4 and 23 in group PR 2. One patient in group PR 4 was an unexpected difficult intubation and was withdrawn from the study. Patients in all three groups were similar in age and weight. Mean (SD, range) patient age in groups PS, PR 4 and PR 2 were 44 (15, 1865) yr, 40 (13, 1861) yr and 39 (11, 1862) yr, respectively. Mean patient weight in groups PS, PR 4 and PR 2 were 75 (10, 4992) kg, 71 (12, 5094) kg and 76 (15, 55100) kg, respectively. All subjects in the study were successfully intubated except for two, both in group PR2. In one of these patients vocal cord relaxation was insufficient to allow passage of a tracheal tube, and purposeful movement continued following induction in another. Subsequently, both patients were intubated following the administration of atracurium 0.5 mg kg1. Scores in the three groups, for each of the five intubation characteristics graded in the study are shown in Fig. 1.
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Baseline preinduction values of MAP and HR were similar in all three groups (P>0.05). Postinduction MAP values decreased from baseline in groups PR 2, PR 4 and PS by 21% (P<0.0001), 28% (P<0.0001) and 8% (P>0.05), respectively. While the difference in post-induction MAP values between groups PR2 and PR4 was not significant (P>0.05), post-induction MAP values were significantly lower in both remifentanil groups compared with group PS (P<0.001). Values of post-induction HR decreased from baseline in groups PR 2 and PR 4 by 14% (P<0.01) and 19% (P<0.001), and increased in group PS by 15% (P<0.01). One patient in group PR 4, whose heart rate fell to 35 beats min1, was treated with glycopyrrolate 500 µg. The mean (SD) times, recorded from the beginning of the propofol injection until the first recognizable breath, were 6.0 (0.9) min in group PS, 9.3 (2.6) min in group PR 2 and 12.8 (2.9) min in group PR 4 (P<0.001 between all groups).
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Comment |
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For an opioid to replace succinylcholine in a rapid sequence induction it should provide optimum intubating conditions, and also allow a rapid return of spontaneous respiration and airway reflexes. Although we demonstrated that patients intubated following remifentanil 4 µg kg1 and succinylcholine 1 mg kg1 had similar intubating conditions, the mean duration of apnoea was more than twice as long in the remifentanil group (12.8 vs 6.0 min in the succinylcholine group). The period of apnoea, following a sufficient dose of remifentanil to ensure optimum intubating conditions, would be unacceptable in rapid sequence induction should intubation fail. Although the opioid antagonist, naloxone, could be administered in these circumstances, the degree to which it might lessen apnoea is as yet undetermined.
Our study indicates a role for remifentanil and propofol as an effective method of tracheal intubation. We hope our described technique will be considered an alternative to the use of neuromuscular blocking drugs for procedures requiring tracheal intubation but not muscle relaxation during surgery, and in situations where the use of neuromuscular blocking agents is contraindicated.
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References |
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