1 Department of Anaesthesia and Intensive Care, City of Vienna Hospital Lainz, A-1130 Vienna, Austria. 2 Department of Anaesthesiology and Intensive Care B, General Hospital, Vienna, Austria. 3 Ludwig Boltzmann Institute for Economics of Medicine in Anaesthesia and Intensive Care, Vienna, Austria*Corresponding author
Accepted for publication: June 10, 2002
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Abstract |
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Methods. Sixty patients were included in a prospective, randomized, single blinded study. All patients received a deep cervical plexus block with 30 ml ropivacaine 0.75% and were randomized to receive either remifentanil 3 µg kg1 h1 or propofol 1 mg kg1 h1. The infusions were started after performing the regional block and were stopped at the end of surgery. Arterial pressure, ECG, ventilatory rate, and PaCO2 were measured continuously and recorded at predetermined times. Twenty-four hours after surgery, patient comfort, and satisfaction were also evaluated.
Results. In three patients, the infusion of remifentanil had to be stopped because of severe respiratory depression or bradycardia. No significant differences were found between the two groups in haemodynamic variables or sedative effects, but there was a significantly greater decrease in ventilatory frequency and increase in PaCO2 in the remifentanil group. The patients subjective impressions and pain control were excellent in both groups.
Conclusion. As a result of the higher incidence of adverse respiratory effects with remifentanil and similar sedative effects, propofol is preferable for sedation during cervical plexus block in elderly patients with comorbid disease at the dosage used.
Br J Anaesth 2002; 89: 63740
Keywords: anaesthetic techniques, regional, cervical plexus; anaesthetics i.v., propofol; analgesics opioid, remifentanil; surgery, carotid endarterectomy; sedation
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Introduction |
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We hypothesized that remifentanil 3 µg kg1 h1 and propofol 1 mg kg1 h1 would be equal in sedative, haemodynamic and respiratory effects, and improved patient acceptability of the technique. In a prospective, randomized, single blinded, and controlled study, we compared these drugs in patients undergoing carotid endarterectomy using deep cervical plexus block.
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Methods and results |
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Before the placement of the cervical plexus block, patients were monitored by five-lead electrocardiography, invasive arterial pressure, ventilatory frequency, and pulse oximetry. Deep cervical plexus block was performed using the single bolus-technique described by Winnie and colleagues2 and a dose of 20 ml of ropivacaine 0.75%. Three millilitres of ropivacaine 0.75% were also injected below the inferior border of the mandible, and 7 ml were used to infiltrate the area of the skin incision. This was followed immediately by the start of an infusion of propofol 1 mg kg1 h1 or remifentanil 3 µg kg1 h1. Preoperatively, and at fixed points (P1=skin incision; P2=1 min after; P3=cross-clamp the carotid; P4=10 min later; P5=open the cross-clamp of the carotid; and P6=end of surgery), mean arterial pressure, heart rate, ventilatory frequency, PaCO2, and sedative effect were noted. Only episodes of bradycardia not related to surgical stimulation were recorded. The effect of sedation was measured on a 5-point scale: (1) awake, (2) tired, (3) very tired, (4) asleep, but wakes up when called by name, or (5) only wakes up when the shoulder is shaken. At the end of surgery, the infusion was stopped and all patients were transferred to the post-anaesthesia care unit. On the first postoperative day, the patients subjective impression of their pain control was recorded using a 10-point visual analogue scale (1=very good, 10=very bad).
Groups were compared using the MannWhitney U test. A P value of 0.05 was considered to be significant. Calculations were performed on a personal computer, using a standard software package (WinstatTM 3.0, Kalmia, US).
Sixty patients (median age 74 yr, range 5483 yr) were investigated. In three patients in the remifentanil group, complications were encountered. In two cases, a bradycardia (heart rate between 30 and 35 beats min1) was detected a few minutes after starting the infusion. In one patient, sedation was excessive and respiratory depression (less than 6 bpm) occurred. The infusion of remifentanil was stopped in each instance and all patients recovered quickly, but were excluded from further evaluation.
After cross clamping of the carotid artery, one patient in the propofol group stopped breathing and lost consciousness. The patients trachea was intubated and general anaesthesia was instituted. Postoperatively, a cerebrovascular accident was diagnosed and the patient was excluded from further evaluation. Four patients in the propofol group (13.8%) and three patients in the remifentanil group (11.1%) required additional local anaesthetic (lidocaine 0.5 %) around and within the carotid sheath.
Nitroglycerin 15 mg h1 to treat hypertension was used in eight patients (26.6%) in the propofol group and seven patients (25.9%) in the remifentanil group. Nausea and vomiting occurred in five patients (16.7%) in the propofol group and seven patients (25.9%) in the remifentanil group. At no point were any differences found between groups in the mean arterial pressure, heart rate, or SpO2. There was no difference in sedative effects between groups. Mean scores ranged between 1.67 and 1.97 in the remifentanil group and between 1.36 and 1.88 in the propofol group.
Mean (range) PaCO2 levels were almost the same preoperatively (remifentanil group 4.78 (4.275.35) kPa vs propofol group 4.85 (3.775.89) kPa). At points 1 and 2, PaCO2 increased significantly (P<0.05) in the remifentanil compared with the propofol group (5.5 (4.127.01) vs 4.92 (3.966.01) kPa and 5.67 (4.86.68) vs 5.18 (4.276.78) kPa). From point 3 to 6, this difference was even more pronounced (P<0.01) (P3: 5.66 (4.796.74) vs 5.19 (4.196.63) kPa; P4: 5.7 (4.86.7) vs 4.94 (4.036.7) kPa; P5: 5.66 (4.876.7) vs 5.03 (4.156.37) kPa; P6: 5.74 (4.536.76) vs 5.05 (4.116.12) kPa). Ventilatory frequency was found to be significantly different between the groups at every time point (P<0.01) (Fig. 1).
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Comment |
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The requirement for additional sedation during carotid endarterectomy results from: inability of the patient to move his head during surgery, causing pain in the cervical spine; or surgical manipulation in the area of the carotid sheath or under the mandible. Additionally, some patients are anxious. Such discomfort can result in adverse cardiovascular events, which are undesirable, as haemodynamic and respiratory instability are associated with a poor outcome after such surgery.4
Propofol is well established for sedation, as is remifentanil during regional anaesthesia.1 5 6 However, there is no concordance about the optimal doses of these drugs in such circumstances and no data are available concerning patients of ASA class IIIIV, the predominant group of patients undergoing this type of surgery. Lauwers and colleagues1 used propofol 3 mg kg1 h1 or remifentanil 6 µg kg1 h1 for sedation during regional anaesthesia, and reported considerable side effects in both groups. Respiratory depression was reported to be more frequent in the remifentanil group. In another study, Lauwers and colleagues6 compared three different doses of remifentanil (2.4 vs 4.2 vs 6 µg kg1 h1) and found significant rates of respiratory depression, nausea, and sweating in all three groups. Using either propofol 4.5 mg kg1 min1 or remifentanil 6 µg kg1 h1, Smith and colleagues7 noted a greater degree of sedation in patients receiving propofol, whereas patients from the remifentanil group had more marked respiratory depression.
Mingus and colleagues8 used higher doses of remifentanil 12 µg kg1 h1 and propofol 6 mg1 kg h1 in patients undergoing orthopaedic and urological surgery. These doses were increased by 50% when patients expressed discomfort, or decreased by 50% in the case of hypoventilation or haemodynamic instability. Remifentanil proved to be more effective than propofol in minimizing pain, but was associated with more respiratory depression and short-term nausea. In our study, 26% of patients in the remifentanil group suffered from nausea and vomiting compared with 17% in the propofol group.
The results reported by Mingus,8 indicate that the remifentanil dose should be reduced to 6 µg kg1 h1 and to 3 µg kg1 h1 in elderly patients. However, our data suggest that in patients over 70 yr of age and classified as ASA III or IV, even a dose of 3 µg kg1 h1 can induce side effects. Thus, we believe that a further reduction in dosage is required. With a dose of propofol 1 mg kg1 h1, we found stable haemodynamics, mild sedation, and no respiratory depression. Using the lowest remifentanil dose (3 µg kg1 h1) recommended by Mingus and colleagues,8 resulted in stable haemodynamics and mild sedation, but respiratory depression was significantly higher than in the propofol group.
We suggest that when using remifentanil for sedation in ASA IIIIV patients undergoing carotid endarterectomy, the initial dose should be decreased to 1.52 µg kg1 h1 to minimize cardiovascular and respiratory complications in these elderly patients with significant comorbidity. A stepwise adaptation of the remifentanil dosage as proposed by Servin and colleagues9 appears to be a promising alternative to a fixed dose regime. However, it remains to be determined whether a reduction in remifentanil dosage to avoid side effects leads to a loss of sedative and analgesic effects.
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References |
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2 Winnie AP, Ramamurthy S, Durrani Z, Radonjic R. Interscalene cervical plexus block: a single-injection technic. Anesth Analg 1975; 54: 3705[Abstract]
3 Davies MJ, Silbert BS, Scott DA, Cook RJ, Mooney PH. Superficial and deep cervical plexus block for carotid artery surgery: a prospective study of 1000 blocks. Reg Anesth 1997; 22: 4426[ISI][Medline]
4 Asiddao CB, Donegan JH, Whitesell RC, Kalbfleisch JH. Factors associated with perioperative complications during carotid endarterectomy. Anesth Analg 1982; 62: 6317
5 White PF, Negus JB. Sedative infusions during local and regional anesthesia: a comparison of midazolam and propofol. J Clin Anesth 1991; 3: 329[Medline]
6 Lauwers M, Camu F, Breivik H, et al. The safety and effectiveness of remifentanil as an adjunct sedative for regional anesthesia. Anesth Analg 1999; 88: 12440
7 Smith I, Avramov MN, White PF. A comparison of propofol and remifentanil during monitored anesthesia care. J Clin Anesth 1997; 9: 14854[ISI][Medline]
8 Mingus ML, Monk TG, Gold MI, Jenkins W, Roland C. Remifentanil versus propofol as adjuncts to regional anesthesia in patients undergoing orthopedic or urogenital surgery. J Clin Anesth 1998; 10: 4653[ISI][Medline]
9 Servin F, Desmonts JM, Watkins WD. Remifentanil as an analgesic adjunct in local/regional anesthesia and in monitored anesthesia care. Anesth Analg 1999; 89: 2832