Bolus dose remifentanil for control of haemodynamic response to tracheal intubation during rapid sequence induction of anaesthesia.

The effect of three bolus doses of remifentanil on the pressor response to laryngoscopy and tracheal intubation during rapid sequence induction of anaesthesia was assessed in a randomized, double-blind, placebo-controlled study in four groups of 20 patients each. After preoxygenation, anaesthesia was induced with thiopental 5-7 mg kg-1 followed immediately by saline (placebo) or remifentanil 0.5, 1.0 or 1.25 micrograms kg-1 given as a bolus over 30 s. Cricoid pressure was applied just after loss of consciousness. Succinylcholine 1 mg kg-1 was given for neuromuscular block. Laryngoscopy and tracheal intubation were performed 1 min later. Arterial pressure and heart rate were recorded at intervals until 5 min after intubation. Remifentanil 0.5 microgram kg-1 was ineffective in controlling the increase in heart rate and arterial pressure after intubation but the 1.0 and 1.25 micrograms kg-1 doses were effective in controlling the response. The use of the 1.25 micrograms kg-1 dose was however, associated with a decrease in systolic arterial pressure to less than 90 mm Hg in seven of 20 patients.

Peribulbar anaesthesia: a double-blind comparison of three local anaesthetic solutions.

A prospective, randomised, double-blinded study comparing three agents for peribulbar anaesthesia is reported. Sixty patients undergoing extracapsular cataract extraction under local anaesthesia were randomly allocated to receive peribulbar anaesthesia with lignocaine 2% with adrenaline; prilocaine 3% with felypressin 0.03 IU.ml-1 or 2% lignocaine and 0.5% bupivacaine in a ratio of 1:1, using a standardised two-injection technique. The pain of injection, time of onset of the block and the operating conditions at the start and finish of surgery were assessed. Peribulbar anaesthesia using lignocaine 2% was significantly more painful than the other solutions. The onset of anaesthesia adequate for surgery was similar in all three groups. Prilocaine 3% with felypressin was associated with the greatest number of blocks providing total akinesia of the eye. Inadequate duration of anaesthesia was seen in only one case; the solution used for this block was 2% lignocaine.

Intrathecal diamorphine for analgesia after caesarean section. A dose finding study and assessment of side-effects.

Eighty women undergoing elective Caesarean section under spinal anaesthesia using hyperbaric bupivacaine 0.5% were randomly allocated to receive, in addition, intrathecal diamorphine 0.125, 0.25 or 0.375 mg or saline. Postoperative morphine requirements, measured using a patient-controlled analgesia system, were reduced in a dose-dependent manner by diamorphine. Pain scores were significantly lower at 2 and 6 h following the two larger doses of diamorphine. Less supplemental analgesia was required intra-operatively if intrathecal diamorphine had been given. The incidences of vomiting and pruritus were also dose-related. No respiratory rates of less than 14 breath.min-1 were recorded and the incidence of oxygen saturation readings less than 95% and 90% did not differ between groups. There were no adverse neonatal effects. Intrathecal diamorphine in the present study was found to be safe in doses of up to 0.375 mg following Caesarean section. However, minor side-effects were frequently observed.

Evaluation of remifentanil for control of haemodynamic response to tracheal intubation.

We have studied the effect of three bolus doses of remifentanil on the haemodynamic response to laryngoscopy and tracheal intubation. Using a double-blind design, 80 ASA 1 or 2 patients presenting for elective surgery received saline placebo or remifentanil 0.25, 0.5 or 1.0 microgram.kg-1 by random allocation. Anaesthesia was induced with thiopentone 5-7 mg.kg-1 and followed immediately by the study medication given as a bolus over 30s. Muscle relaxation was provided with rocuronium 0.75 mg.kg-1. The patients' tracheas were intubated under direct laryngoscopy 1 min later. Noninvasive arterial blood pressure and heart rate were recorded immediately before induction of anaesthesia and then at intervals until 5 min after tracheal intubation. There was a significant increase in heart rate (p < 0.01) and systolic arterial pressure (p < 0.01) in all groups after tracheal intubation. However, this was short-lived and of a smaller magnitude in the remifentanil 1 microgram.kg-1 group in which the increase was significantly lower than in the control group (p < 0.01).

The choice of anesthetic maintenance technique influences the antiinflammatory cytokine response to abdominal surgery.

UNLABELLED: Outcome in some diseases is determined by the relationship between pro- and antiinflammatory cytokines. Surgery may also provoke a cytokine response, which has both pro- and antiinflammatory components. The aim of this study was to ascertain whether anesthetic technique can modify the balance of cytokines associated with abdominal surgery. Twenty patients scheduled to undergo elective abdominal hysterectomy were randomly allocated to receive maintenance of anesthesia with isoflurane (IH group) or propofol (IV group). Venous blood samples for measurement of tumor necrosis factor alpha (TNF-alpha), interleukin-6 (IL-6), interleukin-10 (IL-10), and interleukin-1 receptor antagonist (IL-1ra) were taken before the induction of anesthesia and at set intervals until 24 h postoperatively. TNF-alpha levels remained low throughout the study; however, all patients showed a significant postoperative increase in IL-6, IL-10, and IL-1ra (P < 0.05). Levels of the proinflammatory cytokine IL-6 were similar in both groups, whereas the antiinflammatory cytokine IL-10 was higher in the IV group at 4 h postoperatively (P < 0.02). The difference between groups in terms of IL-1ra production just failed to reach significance (P < 0.06). We conclude that the cytokine response to abdominal surgery has both pro- and antiinflammatory components and that the choice of anesthetic may modify the balance of these cytokines. IMPLICATIONS: This study demonstrates that in addition to the widely reported proinflammatory cytokine response, elective abdominal surgery provokes an antiinflammatory response, which may be enhanced by total intravenous anesthesia. The ability of anesthetics to modify the cytokine response to surgery may have therapeutic potential.

A comparison of the effect of intrathecal and extradural fentanyl on gastric emptying in laboring women.

UNLABELLED: We studied gastric emptying, using acetaminophen absorption, in 105 women in labor divided into three equal groups of 35 each, after intrathecal (i.t.) (25 micrograms, Group S) or extradural (50 micrograms, Group E) fentanyl in combination with bupivacaine and compared with a control group (Group C) receiving extradural bupivacaine only. The time to maximal acetaminophen concentration (tCamax), maximal acetaminophen concentration (Camax), and areas under the acetaminophen concentration-time curve at 90 and 120 min (AUC90 and AUC120, respectively) were determined. Median (range) tCamax values were 120 (15-180), 82.5 (15-180), and 90 (15-180) min in Groups S, E, and C, respectively (P < 0.05). Mean +/- SD Camax was 13.4 +/- 8.82, 17.9 +/- 8.06, and 15.0 +/- 6.22 micrograms/mL in Groups S, E, and C, respectively (P < 0.05). Mean +/- SD AUC90 and AUC120 were also significantly smaller in Group S than in the other two groups (430 +/- 616, 736 +/- 504, and 672 +/- 453; and 649 +/- 592, 1063 +/- 627, and 1053 +/- 616 micrograms.mL-1.min-1 in Groups S, E, and C, respectively). We conclude that the administration of fentanyl 25 micrograms i.t. delays gastric emptying in labor compared with both extradural fentanyl 50 micrograms with bupivacaine and extradural bupivacaine alone. IMPLICATIONS: We examined emptying of the stomach in women in labor after administration of analgesics by the spinal or the epidural route. We observed that the analgesic, fentanyl, administered by the spinal route, although relieving pain rapidly, may delay emptying of the stomach. In theory, delayed gastric emptying may increase the chance of vomiting and aspiration of gastric contents.

Pain relief for thoracotomy. Comparison of morphine requirements using an extrapleural infusion of bupivacaine.

BACKGROUND AND OBJECTIVES: The effectiveness of a continuous infusion of extrapleural bupivacaine for relief of postoperative pain was assessed in patients undergoing posterolateral thoracotomy under general anesthesia by comparing morphine requirements. METHODS: Bupivacaine 0.25% was infused at a rate of 5 mL/h through an unkinkable extrapleural catheter that was sited under direct vision at operation. RESULTS: Mean (+/- SD) 24-hour requirements for morphine from a patient-controlled analgesia device were 39 +/- 15 mg for the treated group and 69 +/- 26 mg in the control group (P < .006). Patients in the treated group recorded significantly smaller visual analog scores for pain both at rest (P < .005) and on movement (P < .03) compared to the control group. There were no adverse effects associated with the use of extrapleural bupivacaine in this study. CONCLUSIONS: Continuous extrapleural infusion of bupivacaine through unkinkable catheters sited during thoracotomy resulted in decreased intravenous patient-controlled analgesia use and decreased verbal categoric pain scores at rest and during movement.

Comparison of the analgesic effects of intrathecal clonidine and intrathecal morphine after spinal anaesthesia in patients undergoing total hip replacement.

We have studied the anaesthetic and analgesic properties of intrathecal clonidine and intrathecal morphine in patients undergoing total hip replacement under spinal anaesthesia. After routine spinal anaesthesia with 0.5% plain bupivacaine 2.75 ml, patients were allocated randomly to receive intrathecal clonidine, morphine or saline (control) as adjuvant to the bupivacaine. Postoperative analgesic effects were measured by consumption of morphine via patient-controlled analgesia and visual analogue pain scores. Both intrathecal clonidine and intrathecal morphine prolonged the time to first analgesia compared with saline (mean 278 (SD 93.2) min, 498 (282.4) min and 54 (61.9) min, respectively) (P < 0.001). Total morphine consumption on the first night after operation was significantly less in the intrathecal morphine group. There were no differences between the clonidine and the control group. Intrathecal clonidine prolonged the duration of spinal analgesia, but was markedly inferior to the intrathecal morphine in providing subsequent postoperative analgesia.

Partial attenuation of the pressor response to endotracheal intubation. A comparison of the effects of intravenous clonidine and fentanyl.

In a randomized, double-blind placebo controlled study, intravenous clonidine, fentanyl and saline were compared for both their effect on the cardiovascular response to intubation, and early post-operative pain. The patients treated with fentanyl and clonidine were more sedated and the requirements for induction agents were lower compared to the control group. On intubation, both the active treatments resulted in a smaller increase in both heart rate and mean arterial pressure compared to the control group. There was no significant difference in recovery times in the three groups. Although the time to first request for analgesia was longer in the clonidine group compared to both the fentanyl and saline groups, the difference in morphine requirements between the groups was not significant. The differences between the two active treatments were not significant, and clonidine offered no additional benefits over fentanyl for this purpose.

Extradural clonidine infusions for analgesia after total hip replacement.

We have examined the effectiveness of extradural clonidine infusions for postoperative analgesia and the effect of clonidine on extradural morphine. In a double-blind, controlled study, patients, undergoing total hip replacement were allocated randomly to receive one of two doses of extradural clonidine (25 micrograms h-1 or 50 micrograms h-1), low dose extradural morphine or a combination of morphine and clonidine. Pain scores in the morphine group were significantly greater than in the clonidine groups (P less than 0.01) and the combination group (P less than 0.05) during the first 1 h after surgery. The requirements for systemic analgesia were least in the combination and larger dose clonidine group, and the duration of effect of the initial bolus dose was significantly longer compared with the morphine and low dose clonidine groups (P less than 0.05). Arterial pressure was reduced in the clonidine groups, although the incidence of clinical hypotension was low. There were no significant differences between the groups in emetic symptoms or urinary retention.

Extradural clonidine and bupivacaine for postoperative analgesia.

We have assessed the use of clonidine and bupivacaine for postoperative analgesia. Both drugs were administered via the extradural route, and were given both alone and in combination. The analgesia produced by clonidine was superior to that of bupivacaine; a combination of the drugs resulted in significantly better and longer duration of analgesia than each drug administered alone. Cardiovascular changes and the incidence of side effects were similar in all three groups. The sedative effects of clonidine were not marked.

The effect of intravenous clonidine on the forearm circulation.

The effect of two doses of clonidine on forearm blood flow was compared with an inert treatment using mercury strain gauge venous occlusive plethysmography. In the clonidine treated groups, forearm blood flow was unaffected in the resting state, but decreased sharply with tracheal intubation. In the saline group, blood flow increased with intubation. Forearm vascular resistance increased in the clonidine treated groups, but decreased in the saline group. These results suggest that clonidine has a peripheral action in anaesthetised normotensive individuals, and is not a purely centrally acting drug.

Adrenergic modulation of preoperative anxiety: a comparison of temazepam, clonidine, and timolol.

To assess the influence of adrenergic modulation on preoperative anxiety, we used a randomized, double-blind, placebo-controlled trial to compare temazepam, clonidine, and timolol as preanesthetic medications in patients undergoing minor orthopedic surgery. All the active treatments resulted in less preoperative anxiety than the placebo (control) did. Induction of anesthesia was smoother in all the treated patients compared with the control group. Recovery was slowest in the temazepam and clonidine groups, but there were no significant differences between the groups after 90 min. Cardiovascular changes were most marked in the timolol group. Pain scores were lower in the temazepam and clonidine series in the early postoperative period. Neither clonidine nor timolol offers any major advantage over temazepam for premedication in these patients.

Cardiovascular effects of intravenous clonidine. Partial attenuation of the pressor response to intubation by clonidine.

The effect of clonidine on the pressor and heart rate response to tracheal intubation was studied in a placebo-controlled, randomised, double-blind trial. Thirty patients were pretreated with either clonidine 1.25 micrograms/kg, or clonidine 0.625 microgram/kg or an equivalent volume of normal saline, given intravenously 15 minutes before induction of anaesthesia. The attenuation of the pressor response to intubation of both clonidine groups was statistically significant compared to the saline group. Neither dose of clonidine completely abolished the increase in either heart rate or blood pressure. There was no difference in attenuation between the clonidine treatments; this indicated that the lower dose may be the more appropriate.

Preanaesthetic medication with clonidine: a dose-response study.

Eighty normotensive female patients were studied in a randomized, double-blind investigation, in which orally administered clonidine 0.1 mg, 0.2 mg and 0.3 mg were compared with a standard benzodiazepine premedicant. Clonidine 0.2 mg produced a significant reduction in anxiety (P less than 0.05) compared with all the other groups, and a better quality of induction of anaesthesia when compared with temazepam 20 mg and clonidine 0.1 mg. The decreases in arterial pressure and heart rate with clonidine 0.3 mg were significant compared with the other treatment groups. Hypotension persisted into the postoperative period after premedication with clonidine 0.3 mg, and this dose is not recommended as a routine premedicant.

Preanaesthetic medication with clonidine.

The purpose of this study was to evaluate oral clonidine in a dose of 0.3 mg as a routine premedicant. Sixty-nine normotensive female patients were studied in a randomized double-blind investigation in which clonidine was compared with an inert treatment. Clonidine produced a significant reduction in anxiety (P less than 0.05) and sedation and a reduction in the sleep dose of methohexitone (P less than 0.05). Tachycardia in response to intubation was attenuated by clonidine (P less than 0.05). However, the magnitude of the increase in arterial pressure after intubation was not affected. Intraoperative and postoperative hypotension were common after premedication with clonidine 0.3 mg and caution is urged in its use as a premedicant.