Effect of sufentanil on bispectral index in the elderly.

We examined the impact of adding sufentanil during anaesthesia induction with propofol on bispectral index values in elderly patients (≥ 65 years). Patients were randomly assigned to receive a target-controlled sufentanil infusion (effect-site concentration of 0.3 ng.ml-1 ) or matching placebo, followed by a target-controlled propofol induction (initial effect-site concentration of 0.5 µg.ml-1 ; step-wise increase of 0.5 µg.ml-1 ) until loss of consciousness defined as an Observer's Assessment of Alertness/Sedation score < 2. Seventy-one patients (sufentanil 35, placebo 36) completed the study. Mean (SD) age was 72.3 (5.8) years; 41% were women. At loss of consciousness, mean (SD) bispectral index value was 75.0 (8.6) with sufentanil and 70.0 (8.0) with placebo; mean difference -5.0 (95% confidence interval -8.9 to -1.1), p = 0.013. Post-hoc analyses suggest that the difference was significant in men only (mean difference -7.3 (-11.8 to -2.6), p = 0.003). Sufentanil co-induction with propofol results in higher bispectral index values at loss of consciousness in elderly patients.

Ventilation strategies in obese patients undergoing surgery: a quantitative systematic review and meta-analysis.

BACKGROUND: Pathophysiological changes due to obesity may complicate mechanical ventilation during general anaesthesia. The ideal ventilation strategy is expected to optimize gas exchange and pulmonary mechanics and to reduce the risk of respiratory complications. METHODS: Systematic search (databases, bibliographies, to March 2012, all languages) was performed for randomized trials testing intraoperative ventilation strategies in obese patients (BMI ≥ 30 kg m(-2)), and reporting on gas exchange, pulmonary mechanics, or pulmonary complications. Meta-analyses were performed when data from at least three studies or 100 patients could be combined. RESULTS: Thirteen studies (505 obese surgical patients) reported on a variety of ventilation strategies: pressure- or volume-controlled ventilation (PCV, VCV), various tidal volumes, and different PEEP or recruitment manoeuvres (RM), and combinations thereof. Definitions and reporting of endpoints were inconsistent. In five trials (182 patients), RM added to PEEP compared with PEEP alone improved intraoperative PaO2/FIO2 ratio [weighted mean difference (WMD), 16.2 kPa; 95% confidence interval (CI), 8.0-24.4] and increased respiratory system compliance (WMD, 14 ml cm H(2)O(-1); 95% CI, 8-20). Arterial pressure remained unchanged. In four trials (100 patients) comparing PCV with VCV, there was no difference in PaO2/FIO2 ratio, tidal volume, or arterial pressure. Comparison of further ventilation strategies or combination of other outcomes was not feasible. Data on postoperative complications were seldom reported. CONCLUSIONS: The ideal intraoperative ventilation strategy in obese patients remains obscure. There is some evidence that RM added to PEEP compared with PEEP alone improves intraoperative oxygenation and compliance without adverse effects. There is no evidence of any difference between PCV and VCV.

Intravenous lidocaine has no impact on rocuronium-induced neuromuscular block. Randomised study.

BACKGROUND: Intravenous lidocaine is increasingly used in surgical patients. As it has neuromuscular blocking effects, we tested the impact of an intravenous lidocaine infusion on the time course of a rocuronium-induced neuromuscular block. METHODS: Fifty-two adults undergoing surgery were randomly allocated to intravenous lidocaine 1.5 mg/kg followed by a continuous infusion of 2 mg/kg/h or physiological saline (control) throughout surgery. Anaesthesia was induced and maintained with a target-controlled propofol infusion and sufentanil. After loss of consciousness, rocuronium 0.6 mg/kg was given. Neuromuscular transmission was measured using train-of-four (TOF)-watch SX (Organon, Swords Co., Dublin, Ireland) acceleromyography. RESULTS: Onset time (to 95% depression of first twitch) was on average 113.9 s (standard deviation 35.3) with lidocaine and 119.5 s (44.9) with saline (P = 0.618). Total recovery time (TOF ratio 0.9) was on average 58.1 min (15.1) with lidocaine and 54.3 min (16.9) with saline (P = 0.394). Clinical duration (until first twitch has recovered to 25%) was on average 33.3 min (7.2) with lidocaine and 30.6 min (8.1) with saline (P = 0.21). Recovery index (time between 25% and 75% recovery of the first twitch) was on average 11.5 min (5.0) with lidocaine and 10.6 min (4.1) with saline (P = 0.458). Recovery time (between 25% recovery of the first twitch and TOF ratio 0.9) was on average 24.8 min (9.3) with lidocaine and 23.2 min (9.2) with saline (P = 0.541). CONCLUSION: A continuous intravenous infusion of lidocaine has no impact on the time course of the neuromuscular blockade induced by a standard intubation dose of rocuronium.

Time course of rocuronium-induced neuromuscular block after pre-treatment with magnesium sulphate: a randomised study.

BACKGROUND: A previously published study suggested that pre-treatment with magnesium sulphate (MgSO(4)) had no impact on the speed of onset of rocuronium-induced neuromuscular block. We set out to verify this assumption. METHODS: Eighty patients (18-60 years) were randomly allocated to MgSO(4) 60 mg/kg or placebo (saline). Study drugs were given intravenously for 15 min before induction of anaesthesia with propofol, sufentanil and rocuronium 0.6 mg/kg. Anaesthesia was maintained with a target-controlled propofol infusion. Neuromuscular transmission was measured using train-of-four (TOF)-Watch SX acceleromyography. RESULTS: Onset was analysed in 37 MgSO(4) and 38 saline patients, and recovery in 35 MgSO(4) and 37 saline patients. Onset time (to 95% depression of T1) was on average 77 [SD=18] s with MgSO(4) and 120 [48] s with saline (P<0.001). The total recovery time (DurTOF0.9) was on average 73.2 [22] min with MgSO(4) and 57.8 [14.2] min with saline (P<0.003). The clinical duration (Dur25%) was on average 44.7 [14] min with MgSO(4) and 33.2 [8.1] min with saline (P<0.0002). The recovery index (Dur25-75%) was on average 14.0 [6] min with MgSO(4) and 11.2 [5.2] min with saline (P<0.02). The recovery time (Dur25%TOF0.9) was on average 28.5 [11.7] min with MgSO(4) and 24.7 [8.4] min with saline (P=0.28). CONCLUSION: Magnesium sulphate given 15 min before propofol anaesthesia reduces the onset time of rocuronium by about 35% and prolongs the total recovery time by about 25%.

Bispectral and spectral entropy indices at propofol-induced loss of consciousness in young and elderly patients.

BACKGROUND: Bispectral (BIS) and state/response entropy (SE/RE) indices have been widely used to estimate depth of anaesthesia and sedation. In adults, independent of age, adequate and safe depth of anaesthesia for surgery is usually assumed when these indices are between 40 and 60. Since the EEG is changing with increasing age, we investigated the impact of advanced age on BIS, SE, and RE indices during induction. METHODS: BIS and SE/RE indices were recorded continuously in elderly (> or =65 yr) and young (< or =40 yr) surgical patients who received propofol until loss of consciousness (LOC) using stepwise increasing effect-site concentrations. LOC was defined as an observer assessment of alertness/sedation score <2, corresponding to the absence of response to mild prodding or shaking. RESULTS: We analysed 35 elderly [average age, 78 yr (range, 67-96)] and 34 young [35 (19-40)] patients. At LOC, all indices were significantly higher in elderly compared with young patients: BIS(LOC), median 70 (range, 58-91) vs 58 (40-70); SE(LOC), 71 (31-88) vs 55.5 (23-79); and RE(LOC), 79 (35-96) vs 59 (25-80) (P<0.001 for all comparisons). With all three monitors, only a minority of elderly patients lost consciousness within a 40-60 index range: two (5.7%) with BIS and RE each, and seven (20%) with SE. In young patients, the respective numbers were 20 (58.8%) for BIS, 13 (38.2%) for SE, and nine (26.5%) for RE. CONCLUSIONS: In adults undergoing propofol induction, BIS, SE, and RE indices at LOC are significantly affected by age.

Benefit and risk of intrathecal morphine without local anaesthetic in patients undergoing major surgery: meta-analysis of randomized trials.

Intrathecal morphine without local anaesthetic is often added to a general anaesthetic to prevent pain after major surgery. Quantification of benefit and harm and assessment of dose-response are needed. We performed a meta-analysis of randomized trials testing intrathecal morphine alone (without local anaesthetic) in adults undergoing major surgery under general anaesthesia. Twenty-seven studies (15 cardiac-thoracic, nine abdominal, and three spine surgery) were included; 645 patients received intrathecal morphine (dose-range, 100-4000 microg). Pain intensity at rest was decreased by 2 cm on the 10 cm visual analogue scale up to 4 h after operation and by about 1 cm at 12 and 24 h. Pain intensity on movement was decreased by 2 cm at 12 and 24 h. Opioid requirement was decreased intraoperatively, and up to 48 h after operation. Morphine-sparing at 24 h was significantly greater after abdominal surgery {weighted mean difference, -24.2 mg [95% confidence interval (CI) -29.5 to -19.0]}, compared with cardiac-thoracic surgery [-9.7 mg (95% CI -17.6 to -1.80)]. The incidence of respiratory depression was increased with intrathecal morphine [odds ratio (OR) 7.86 (95% CI 1.54-40.3)], as was the incidence of pruritus [OR 3.85 (95% CI 2.40-6.15)]. There was no evidence of linear dose-responsiveness for any of the beneficial or harmful outcomes. In conclusion, intrathecal morphine decreases pain intensity at rest and on movement up to 24 h after major surgery. Morphine-sparing is more pronounced after abdominal than after cardiac-thoracic surgery. Respiratory depression remains a major safety concern.

Nefopam for the prevention of postoperative pain: quantitative systematic review.

Nefopam, a centrally acting analgesic, has been used in the surgical setting in many countries since the mid-1970s. However, clinical trials provide contflicting results for its analgesic potency. We performed a systematic search (multiple databases, bibliographies, any language, to January 2008) for randomized, placebo-controlled trials of nefopam for the prevention of postoperative pain. Data were combined using classic methods of meta-analyses and were expressed as weighted mean difference (WMD), relative risk (RR), and number needed to treat/harm (NNT/H) with 95% confidence interval (CI). Nine trials (847 adult patients, 359 received nefopam) were included. Nefopam (cumulative doses, 20-160 mg) was given orally or i.v., as single or multiple doses, or as a continuous infusion. Compared with placebo, cumulative 24 h morphine consumption was decreased with nefopam: WMD -13 mg (95% CI -17.9 to -8.15). Pain intensity at 24 h was also decreased: on a 100 mm visual analogue scale, WMD -11.5 mm (95% CI -15.1 to -7.85). The incidence of tachycardia was increased with nefopam (RR 3.12, 95% CI 1.11-8.79; NNH 7), as was the incidence of sweating (RR 4.92, 95% CI 2.0-12.1; NNH 13). There is limited evidence from the published literature that nefopam may be a useful non-opioid analgesic in surgical patients. The analgesic potency seems to be similar to non-steroidal anti-inflammatory drugs. However, dose responsiveness and adverse effect profile remain unclear, and the role of nefopam as part of multimodal analgesia needs to be established. Data in children are lacking.

Impact of the intubation model on the efficacy of rocuronium during rapid sequence intubation: systematic review of randomized trials.

BACKGROUND: Propofol-rocuronium is thought to be superior to thiopental-rocuronium for rapid sequence intubation (RSI). The role of the intubation model per se has never been investigated. METHODS: Randomized comparisons of rocuronium with succinylcholine for true RSI (administration of muscle relaxant immediately after the hypnotic, intubation within 60 s) or modified RSI (delay between administration of the hypnotic and the muscle relaxant, intubation within 60 s) were sought. Good or excellent intubation conditions were expressed as relative risks (RR) with 95% confidence intervals (CI). RESULTS: Twelve trials (1,471 patients) used a true RSI. With propofol for induction, RR for good or excellent intubation conditions with conventional rocuronium doses (0.6-0.7 mg/kg) was 0.95 (95%CI, 0.90-1.00), with high doses (0.9-1.2 mg/kg) was 0.96 (0.92-1.01) compared with succinylcholine. With thiopental for induction, RR with conventional rocuronium doses was 0.69 (0.61-0.78) and with high doses was 0.99 (0.95-1.03). Nine trials (340 patients) used a modified RSI. With propofol for induction, RR with conventional rocuronium doses was 0.98 (0.91-1.06); data on high rocuronium doses were lacking. With thiopental for induction, RR with conventional rocuronium doses was 0.97 (0.92-1.02) and with high doses was 1.0. There was no evidence that concomitantly used opioids or the dose of the induction agent had an impact on intubation conditions, independent of the intubation model. CONCLUSION: The efficacy of rocuronium for RSI is influenced by both, the induction agent and the intubation model. To test the clinical usefulness of alternatives to succinylcholine for RSI, a true RSI model should be used.

The effect of cigarette smoking on the hypnotic efficacy of propofol.

The bispectral index (BIS) was used to examine the hypnotic efficacy of propofol in 25 smokers (20 cigarettes/day for 2 years) and 24 matched non-smokers (same gender, age, height, weight). BIS was recorded at baseline, at four incremental effect-site concentrations of propofol and at loss of consciousness. Compared with non-smokers, smokers were found to have higher BIS values at baseline (mean (SD)) (97 (1) vs 98 (1)), at 0.7 microg x ml(-1) (95 (3) vs 97 (1)) and at 1.1 microg x ml(-1) (89 (6) vs 94 (4)), p = 0.0099, and they lost consciousness at higher propofol concentrations (2.0 (0.4) vs 2.4 (0.8) microg x ml(-1)), p = 0.03, and at lower BIS values (66 (10) vs 60 (10)), p = 0.04. The hypnotic efficacy of propofol is reduced when used at low effect-site concentrations in smokers. This phenomenon may have some impact on the management of smokers undergoing sedation using target controlled infusion systems.

[High altitude cerebral oedema]. / Oedème cérébral de haute altitude.

Acute mountain sickness and high altitude cerebral edema are specific pathologies of high altitude exposure. The usual symptoms of acute mountain sickness are headache, nausea, vomiting, insomnia, lassitude, dizziness and ataxia. High altitude cerebral oedema is a severe state of acute mountain sickness with, in addition, alteration of mental status and consciousness. The pathophysiology of these 2 diseases are essentially due to an increase of intracranial pressure directly dependent of an increase of cerebral volume. Molecular and cellular mechanisms underlying acute mountain sickness and high altitude cerebral oedema are still poorly understood. The regulation of cerebral blood flow by nitric oxide seems to play a major role.

Propofol 1% versus propofol 2% in children undergoing minor ENT surgery.

BACKGROUND: The induction characteristics of propofol 1% and 2% were compared in children undergoing ENT surgery, in a prospective, randomized, double-blind study. METHODS: One hundred and eight children received propofol 1% (n=55) or 2% (n=53) for induction and maintenance of anaesthesia. For induction, propofol 4 mg kg(-1) was injected at a constant rate (1200 ml h(-1)), supplemented with alfentanil. Intubating conditions without the use of a neuromuscular blocking agent were scored. RESULTS: Pain on injection occurred in 9% and 21% of patients after propofol 1% and 2%, respectively (P=0.09). Loss of consciousness was more rapid with propofol 2% compared with propofol 1% (47 s vs 54 s; P=0.02). Spontaneous movements during induction occurred in 22% and 34% (P=0.18), and intubating conditions were satisfactory in 87% and 96% (P=0.19) of children receiving propofol 1% or 2%, respectively. There were no differences between the two groups in respect of haemodynamic changes or adverse events. CONCLUSIONS: For the end-points tested, propofol 1% and propofol 2% are similar for induction of anaesthesia in children undergoing minor ENT surgery.

Transcranial Doppler versus angiography in patients with vasospasm due to a ruptured cerebral aneurysm: A systematic review.

BACKGROUND AND PURPOSE: Transcranial Doppler (TCD) is used for diagnosis of vasospasm in patients with subarachnoid hemorrhage due to a ruptured aneurysm. Our aim was to evaluate both the accuracy of TCD compared with angiography and its usefulness as a screening method in this setting. METHODS: A search (MEDLINE, EMBASE, Cochrane Library, bibliographies, hand searching, any language, through January 31, 2001) was performed for studies comparing TCD with angiography. Data were critically appraised using a modified published 10-point score and were combined using a random-effects model. RESULTS: Twenty-six reports compared TCD with angiography. Median validity score was 4.5 (range 1 to 8). Meta-analyses could be performed with data from 7 trials. For the middle cerebral artery (5 trials, 317 tests), sensitivity was 67% (95% CI 48% to 87%), specificity was 99% (98% to 100%), positive predictive value (PPV) was 97% (95% to 98%), and negative predictive value (NPV) was 78% (65% to 91%). For the anterior cerebral artery (3 trials, 171 tests), sensitivity was 42% (11% to 72%), specificity was 76% (53% to 100%), PPV was 56% (27% to 84%), and NPV was 69% (43% to 95%). Three of these 7 studies reported on the same patients, each on another artery, and for 4, data recycling could not be disproved. Other arteries were tested in only 1 trial each. CONCLUSIONS: For the middle cerebral artery, TCD is not likely to indicate a spasm when angiography does not show one (high specificity), and TCD may be used to identify patients with a spasm (high PPV). For all other situations and arteries, there is either lack of evidence of accuracy or of any usefulness of TCD. Most of these data are of low methodological quality, bias cannot not be ruled out, and data reporting is often uncritical.

Effects of fentanyl, alfentanil, remifentanil and sufentanil on loss of consciousness and bispectral index during propofol induction of anaesthesia.

The bispectral index (BIS) and a sedation score were used to determine and compare the effect of propofol in the presence of fentanyl, alfentanil, remifentanil and sufentanil. Seventy-five non-premedicated patients were assigned randomly into five groups (15 in each) to receive fentanyl, alfentanil, remifentanil, sufentanil or placebo. Opioids were administered using a target-con-trolled infusion device, to obtain the following predicted effect-site concentrations: fentanyl, 1.5 ng ml(-1); alfentanil, 100 ng ml(-1); remifentanil, 6 ng ml(-1); and sufentanil, 0.2 ng ml(-1). After this, a target-controlled infusion of propofol (Diprifusor) was started to increase concentration gradually, to achieve predicted effect-site concentrations of 1, 2, and 4 microg ml(-1). At baseline and at each successive target effect-site concentration of propofol, the BIS, sedation score and haemodynamic variables were recorded. At the moment of loss of consciousness (LOC), the BIS and the effect-site concentration of propofol were noted. The relationship between propofol effect-site concentration and BIS was preserved with or without opioids. In the presence of an opioid, LOC occurred at a lower effect-site concentration of propofol and at a higher BIS50 (i.e. the BIS value associated with 50% probability of LOC), compared with placebo. Although clinically the hypnotic effect of propofol is enhanced by analgesic concentrations of mu-agonist opioids, the BIS does not show this increased hypnotic effect.

Mivacurium or vecuronium for paediatric ENT surgery. Clinical experience and cost analysis.

BACKGROUND: The present study compared the quality of neuromuscular block and costs after equipotent doses of mivacurium and vecuronium in the context of paediatric ENT surgery. METHODS: A total of 30 children undergoing elective tonsillectomy were included and randomised in two groups (n = 15 for each) according to the neuromuscular blocking agent (NMBA) used. Anaesthesia was induced with alfentanil (15 micrograms/kg), propofol (3 mg/kg) and either 0.2 mg/kg mivacurium or 0.14 mg/kg vecuronium. For maintenance of anaesthesia propofol (8-12 mg/kg/h) was given. Neuromuscular block was assessed by electromyography using train-of four stimulation and the following parameters were quantified: Twitch height (T1) 2 min after the initial bolus of the myorelaxant; duration until recovery to 10% T1, number and duration of bolus injections of the myorelaxant needed to maintain neuromuscular block to a T1 < 10%. In addition, the intubating conditions, number of patients needing pharmacological reversal at the end of surgery, adverse reactions and the costs for neuromuscular block and pharmacological antagonization were assessed. RESULTS: Intubation conditions were comparable between both study groups: mivacurium--excellent: 7, good: 5, not acceptable: 1; vecuronium--excellent: 11, good: 4 (n.s.). T1 at 2 min was 16 (15)% for mivacurium and 6 (9)% for vecuronium (P < 0.05). Time to 10% T1 recovery was 6.1 (1.7) min for mivacurium and 21.8 (3.7) min for vecuronium (P < 0.01). In the mivacurium group 7 repetitive doses (range: 4-18) were needed to maintain T1 < 10% during surgery, whereas children treated with vecuronium needed only 1 maintenance dose (range: 0-2) (P < 0.01). Two children in the mivacurium group and 11 in the vecuronium group required pharmacological reversal of the NMB at the end of surgery (P < 0.01). The overall costs of NMB were significantly higher in the mivacurium group as compared to vecuronium 12.88 (4.5) Euro vs 9.96 (2.4) Euro; P < 0.05. CONCLUSIONS: In conclusion, mivacurium-induced NMB is of very short duration in paediatric patients, and therefore repetitive doses are required to maintain a deep neuromuscular block. Nevertheless, residual paralysis is less frequent after mivacurium. The neuromuscular block after mivacurium was more expensive and residual paralysis less frequent compared to vecuronium.