The 50% and 95% effective doses of desflurane for removal of the classic laryngeal mask airway after suction of the upper airway, in anaesthetised spontaneously breathing adult patients, are not known. To determine these, we studied 38 healthy patients, aged between 18 and 44 years. The target desflurane concentration in each individual patient was determined by the Dixon up-and-down method. When the predetermined target end-tidal desflurane concentration reached steady state, we kept a constant end-expiratory partial pressure between the alveolus and the brain for 10 min before attempting to remove the classic laryngeal mask airway after suctioning the upper airway. The initial desflurane target concentration was set at 6% and up-down desflurane increments were 0.1%. This continued until there were at least six crossover pairs. From the probit analysis, the 50% effective dose of desflurane was 5.29% (95% CI 5.132-5.379%) and the 95% effective dose was 5.55% (95% CI 5.429-6.394%).
We compared the performance of the Ambu AuraOnce Laryngeal Mask with that of the LMA Classic laryngeal mask airway during controlled anaesthesia. Forty patients requiring intermittent positive pressure ventilation were studied using a randomised crossover design. The mean (SD) oropharyngeal leak pressure for the Ambu device (19 (7.5) cmH2O) was significantly greater than for the LMA Classic (15 (5.2) cmH2O; p = 0.004), and the number of attempts for successful insertions was significantly less (39 (50%) vs 45 (56%), respectively; p = 0.02). There was one failure to obtain a patent airway with the Ambu Laryngeal Mask and none with the LMA Classic. Insertion of the Ambu Laryngeal Mask required more manipulations to achieve a patent airway than did the LMA Classic (6 (15%) vs 1 (2.5%), respectively; p = 0.045), but the time taken for insertion was similar between the two groups. The incidence of trauma, grade of fibreoptic view, peak airway pressure and quality of ventilation during maintenance of anaesthesia were similar in both groups.
Obesity is becoming a major public health problem throughout the world. It is now the second leading cause of death in the United States and is associated with significant, potentially life-threatening co-morbidities. Significant advances in the understanding of the physiology of body weight regulation and the pathogenesis of obesity have been achieved. A better understanding of the physiology of appetite control has enabled advances in the medical and surgical treatment of obesity. Visceral or abdominal obesity is associated with an increased risk of cardiovascular disease and type 2 diabetes. Various drugs are used in the treatment of mild obesity but they are associated with adverse effects. Surgery has become an essential part of the treatment of morbid obesity, notwithstanding the potential adverse events that accompany it. An appreciation of these problems is essential to the anaesthetist and intensivist involved in the management of this group of patients.
Surgical drapes used during eye surgery are impermeable to air and hence risk trapping air underneath them. We investigated the effect of a forced-air warming blanket on carbon dioxide accumulation under the drapes in patients undergoing eye surgery under local anaesthesia without sedation. Forty patients of ASA physical status 1 and 2 were randomly assigned to either the forced-air warmer (n = 20) or a control heated overblanket (n = 20). All patients were given 1 l.min(-1) oxygen. We measured transcutaneous and end-tidal carbon dioxide partial pressures, heart rate, arterial pressure, respiratory rate, temperature and oxygen saturation before and after draping, then every 5 min thereafter for 30 min. The mean (SD) transcutaneous carbon dioxide partial pressure in the forced-air warming group stayed constant after draping at 5.7 (0.2) kPa but rose to a maximum of 6.4 (0.4) kPa in the heated overblanket group (p = 0.0001 for the difference at time points 15 min and later). We conclude that forced-air warming reduces carbon dioxide accumulation under the drapes in patients undergoing eye surgery under local anaesthesia.
In Study A, the incidence of arterial oxygen desaturation was studied using pulse oximetry (SaO2) in 100 sedated and 100 nonsedated patients breathing room air who underwent diagnostic upper gastrointestinal endoscopy. Hypoxia (SaO2 92% or less of at least 15 s duration) occurred in 17% and 6% of sedated patients and nonsedated patients, respectively (p < 0.03). Mild desaturation (SaO2 94% or less and less than 15 s duration) occurred in 47% of sedated patients compared with 12% of nonsedated patients (p < 0.001). In Study B, the effects of supplementary oxygen therapy and the effects of different pre-oxygenation times on arterial oxygen saturation (SaO2) in sedated patients were studied using pulse oximetry. One hundred and twenty patients who underwent diagnostic upper gastrointestinal endoscopy with intravenous sedation were studied. Patients were randomly allocated to one of four groups: Group A (n = 30) received no supplementary oxygen while Groups B-D received supplementary oxygen at 4 1 x min(-1) via nasal cannulae. The pre-oxygenation time in Group B (n = 30) was zero minutes, Group C (n = 30) was 2 min and Group D (n = 30) was 5 min before sedation and introduction of the endoscope. Hypoxia occurred in seven of the 30 patients in Group A and none in groups B, C and D (p < 0.001). We conclude that desaturation and hypoxia is common in patients undergoing upper gastrointestinal endoscopy with and without sedation. Sedation significantly increases the incidence of desaturation and hypoxia. Supplementary nasal oxygen at 4 1 x min(-1) in sedated patients abolishes desaturation and hypoxia. Pre-oxygenation confers no additional benefit.
We conducted a double-blind, randomised, placebo-controlled study evaluating the efficacy of prophylactic metaraminol for preventing propofol-induced hypotension. Thirty patients aged 55-75 years undergoing general anaesthesia were randomly allocated to receive either metaraminol 0.5 mg or saline before administration of fentanyl 1 microg.kg(-1) and propofol 2 mg.kg(-1). Induction of anaesthesia was associated with a decrease in mean and systolic arterial pressure in both groups (p = 0.0001). However, there was no significant difference between the two groups. These results show that prophylactic use of metaraminol 0.5 mg does not prevent the decrease in blood pressure following fentanyl and propofol induction in older patients.
The efficacy of epidurally administered tramadol hydrochloride, a weak centrally acting analgesic, was studied for the relief of postoperative pain. Sixty patients undergoing abdominal surgery were randomly allocated to three treatment groups to be given the following agents by the epidural route: group 1 tramadol 50 mg; group 2 tramadol 100 mg; group 3 10 ml of bupivacaine 0.25%. The drugs were administered at the patients' request with each patient being allowed four doses in the first 24 h following surgery. Blood pressure, pulse rate, respiratory rate, arterial blood gas analyses, pain scores, the interval between doses and the occurrence of any side effects were recorded. Pain scores (assessed using a visual analogue scale) were significantly less (p < 0.05) at 3, 12, and 24 h in patients receiving tramadol 100 mg than in those receiving tramadol 50 mg or bupivacaine. The mean interval between doses for groups 1, 2 and 3 was 7.40 h, 9.36 h and 5.98 h respectively. The mean interval in group 2 was significantly longer than in group 3 (p < 0.05). The incidence of nausea and vomiting in group 2 was significantly higher than in group 3 (p < 0.05).
Forty patients without eye disease, undergoing elective nonophthalmic surgery, were studied in a double-blind, randomised, placebo-controlled study evaluating the efficacy of mivacurium pretreatment in attenuating the rise in intra-ocular pressure in response to suxamethonium administration, laryngoscopy and intubation. The patients were randomly allocated to receive either mivacurium 0.02 mg.kg-1 or normal saline as pretreatment 3 min before a rapid sequence induction technique using alfentanil, propofol and suxamethonium. Suxamethonium induced a significant increase in intra-ocular pressure in the control group but not in the mivacurium pretreatment group (mean (SEM) increase = 3.5 (1.2) mmHg vs. 0.4 (0.8) mmHg, p < 0.05). There was a decrease in intra-ocular pressure in both groups after laryngoscopy and intubation with no significant difference between the two groups. These results show that mivacurium pretreatment is effective in preventing the increase in intra-ocular pressure after suxamethonium administration.
A case of severe bronchospasm occurring during epidural anaesthesia in a patient undergoing Caesarean section is described. The aetiology of the bronchospasm may have been related to sympathetic nervous blockade allowing unopposed parasympathetically mediated bronchoconstriction.
A 62-year-old male underwent off-pump coronary artery grafting surgery while cerebral function was monitored with bispectral index (BIS). The BIS monitoring was continued into the immediate postoperative period, during which time the patient experienced a cardiopulmonary arrest. The changes in the BIS values helped the resuscitating team in assessing the cerebral response to the cardiopulmonary resuscitation.
Delirium is common in intensive care patients. Dexmedetomidine is increasingly used for sedation in this setting, but its effect on delirium remains unclear. The primary aim of this review was to examine whether dexmedetomidine reduces the incidence of delirium and agitation in intensive care patients. We sought randomised clinical trials in MEDLINE, EMBASE, PubMed and CENTRAL from their inception until June 2018. Observational studies, case reports, case series and non-systematic reviews were excluded. Twenty-five trials including 3240 patients were eligible for inclusion in the data synthesis. In the patients who received dexmedetomidine (eight trials, 1425 patients), delirium was reduced, odds ratio (95%CI) 0.36 (0.26-0.51), p
Loop diuretics remain a fundamental pharmacological therapy to remove excess fluid and improve symptom control in acute decompensated heart failure. Several recent randomised controlled trials have examined the clinical benefit of continuous vs. bolus furosemide in acute decompensated heart failure, but have reported conflicting findings. The aim of this review was to compare the effects of continuous and bolus furosemide with regard to mortality, length of hospital stay and its efficacy profile in acute decompensated heart failure. All parallel-arm randomised controlled trials from MEDLINE, EMBASE, PubMed and the Cochrane Database of Systematic Reviews from inception until May 2017 were included. Cross-over randomised controlled trials, observational studies, case reports, case series and non-systematic reviews that involved children were excluded. Eight trials (n = 669) were eligible for inclusion. There was no difference between furosemide continuous infusion and bolus administration for all-cause mortality (four studies; n = 491; I2 = 0%; OR 1.65; 95%CI 0.93-2.91; p = 0.08) or duration of hospitalisation (six studies; n = 576; I2 = 71%; mean difference 0.27; 95%CI -1.35 to 1.89 days; p = 0.74). Continuous infusion of intravenous furosemide was associated with increased weight reduction (five studies; n = 516; I2 = 0%; mean difference 0.70; 95%CI 0.12-1.28 kg; p = 0.02); increased total urine output in 24 h (four studies; n = 390; I2 = 33%; mean difference 461.5; 95%CI 133.7-789.4 ml; p < 0.01); and reduced brain natriuretic peptide (two studies; n = 390; I2 = 0%; mean difference 399.5; 95%CI 152.7-646.3 ng.l-1 ; p < 0.01), compared with the bolus group. There was no difference in the incidence of raised creatinine and hypokalaemia between the two groups. In summary, there was no difference between continuous infusion and bolus of furosemide for all-cause mortality, length of hospital stay and electrolyte disturbance, but continuous infusion was superior to bolus administration with regard to diuretic effect and reduction in brain natriuretic peptide.