Comparison of the Baska(®) mask with the single-use laryngeal mask airway in low-risk female patients undergoing ambulatory surgery.

We compared the Baska(®) mask with the single-use classic laryngeal mask airway (cLMA) in 150 females at low risk for difficult tracheal intubation in a randomised, controlled clinical trial. We found that median (IQR [range]) seal pressure was significantly higher with the Baska mask compared with the cLMA (40 (34-40 [16-40]) vs 22 (18-25 [14-40]) cmH2O, respectively, p < 0.001), indicating a better seal. In contrast, the first time success rate for insertion of the Baska mask was lower than that seen with the cLMA (52/71 (73%) vs 77/99 (98%), respectively, p < 0.001). There were no differences in overall device insertion success rates (78/79 (99%) vs 68/71 (96%), respectively, p = 0.54). The Baska mask proved more difficult to insert, requiring more insertion attempts, taking longer to insert and had higher median (IQR [range]) insertion difficulty scores (1.6 (0.8-2.2 [0.1-5.6]) vs 0.5 (0.3-1.4 [0.1-4.0]), respectively, p < 0.001). There was also an increased rate of minor blood staining of the Baska mask after removal, but there were no differences in other complication rates, such as laryngospasm, or in the severity of throat discomfort. In conclusion, in clinical situations where the seal with the glottic aperture takes priority over ease of insertion, the Baska mask may provide a useful alternative to the cLMA.

Effects of preoperative methoxamine on blood loss and haemodynamic variables during transurethral prostatic resection under spinal anaesthesia.

Thirty-six patients who presented for transurethral prostatic resection were allocated randomly to one of two groups. Patients in group A were given methoxamine 10 mg i.m., 15 min before spinal anaesthesia. Patients in group B acted as a control group. All patients received spinal anaesthesia. Preoperative administration of methoxamine 10 mg i.m. decreased blood loss significantly and improved haemodynamic stability compared with the control group.

Regional anesthesia for major vascular surgery.

The relative merits of general vs regional anesthesia for patients undergoing major vascular surgery has been the subject of debate over the past decade. Previous studies of regional vs general anesthesia often were deficient in experimental design and, therefore, did not produce definitive answers. Some of these deficiencies related to non-standardized, poorly conducted, and/or described general anesthetic techniques, nonstandardized methods of postoperative analgesia in the general anesthesia groups, and variations in preoperative cardiac status in the study groups. Furthermore, most studies did not conclusively demonstrate a cause and effect relationship between the proposed mechanisms of the beneficial effect of regional anesthesia and outcome. Recent studies, however, have claimed improvements in outcome following regional anesthesia in patients undergoing peripheral vascular procedures. The reported beneficial effects have included amelioration of the neuroendocrine stress response to surgery, improvement in pulmonary function, cardiovascular stability, enhancement of lower limb blood flow, reduction in the incidence of graft thrombosis, and a reduction in the thrombic response to surgery. Skeptics still question whether recent studies have the power to determine whether regional anesthesia decreases the incidence of cardiac and pulmonary complications following major vascular surgery. Furthermore, the issue of whether the beneficial effects of regional anesthesia on the incidence of graft thrombosis and the thrombotic response to surgery relating to intraoperative or postoperative regional anesthesia/analgesia, to regional anesthesia per se, or to the systemic effects of absorbed local anesthetics remains unresolved.

The influence of naloxone infusion on the action of intrathecal diamorphine: low-dose naloxone and neuroendocrine responses.

The influence of an intravenous infusion of naloxone 1 microgram kg-1 h-1, in combination with intrathecal diamorphine, on analgesia and hormonal stress responses after laminectomy was assessed in a blinded, randomized, placebo-controlled study. Twenty-seven patients undergoing laminectomy with postoperative analgesia provided by intrathecal diamorphine were investigated. Analgesia was reduced by naloxone (P less than 0.05), and the duration of analgesia was shortened by 180 min. The postoperative concentrations of both blood glucose and serum cortisol were reduced in the naloxone group compared to the control group (P less than 0.05). These results may indicate an excitatory role for the hypothalamic mu receptor in hypothalamo-pituitary-adrenocortical axis regulation.

HELLP syndrome: a case report with guidelines for diagnosis and management.

A 25-yr-old patient with a twin pregnancy of 34 weeks gestation developed HELLP syndrome and required urgent delivery by Caesarean section. Before operation, a central venous catheter and urinary catheter were inserted, and fresh frozen plasma and platelets were administered to correct hypovolaemia and severe thrombocytopenia. This case demonstrates the critical condition of these patients before operation and that extensive preoperative preparation and invasive monitoring are necessary for successful management. The choice of anaesthetic is governed by the presence of liver and renal dysfunction and severe thrombocytopenia.

Post-cannulation radial artery aneurysm--a rare complication.

The following case report describes an expanding aneurysmal dilatation of the radial artery which developed 17 days following cannulation. Possible causes of this complication are: abnormal state of the vessel wall, multiple attempts at cannulation, and haematoma or infection at cannulation site. Other major and minor sequelae following arterial cannulation are reviewed.

The effect of local anaesthetics on epinephrine absorption following rectal mucosal infiltration.

This study was undertaken to investigate the effects of lidocaine and bupivacaine on epinephrine absorption following rectal mucosal infiltration, to assess the cardiovascular and metabolic effects of the absorbed epinephrine and to compare the systemic absorption of the local anaesthetics employed. Three groups of five greyhounds received 1.5 micrograms.kg-1 of epinephrine 1:200,000 in lidocaine 0.5 per cent, bupivacaine 0.5 per cent or 0.9 per cent saline. Plasma epinephrine, lidocaine, bupivacaine, lactate, glucose and potassium concentrations were measured at 1, 2, 5, 10, 15 and 30 minutes following infiltration. Plasma epinephrine concentrations were significantly higher in the lidocaine group at one and two minutes following infiltration. Plasma bupivacaine concentrations were significantly higher than plasma lidocaine concentrations throughout the study period. There were no significant differences in metabolic or biochemical indices within or between the three groups. A local vasodilatory action of lidocaine may enhance epinephrine absorption. Differences in hepatic uptake and rate of metabolism may explain the increased plasma bupivacaine measured. Lidocaine may be the local anaesthetic of choice for ano-rectal procedures, especially when large volumes of local anaesthetic are being infiltrated.

The influence of collateral vascularisation on haemodynamic performance during abdominal aortic surgery.

The extent of periaortic collateral vascularisation has been proposed as a possible mechanism of an altered haemodynamic response to infra-renal aortic cross-clamp in patients undergoing by-pass grafting for aorto-iliac occlusive disease (AOD) compared with patients undergoing abdominal aortic aneurysm (AAA) resection. The haemodynamic responses following clamping, during the clamp time and following clamp release were studied in 18 patients undergoing AAA resection and 12 patients undergoing bypass grafting for AOD. The role of preoperative aortography in predicting cardiovascular performance during aortic vascular surgery was assessed. During the cross-clamp period LVSWI and CI decreased while SVR increased in the AAA group while the AOD group showed an improved CI, stable LVSWI and reduced SVR, which correlated with the extent of periaortic vascularisation on preoperative aortography. Chronic collateral circulation associated with AOD may permit continuous lower extremity perfusion during aortic cross-clamp. The extent of periaortic collateralisation may influence the choice of monitoring techniques and anaesthetic management.

Radionuclide ventriculography and two dimensional echocardiography as predictors of left ventricular performance during aortic vascular surgery.

Sixteen consecutive patients scheduled for elective aortic vascular surgery underwent preoperative LVEF determination employing two dimensional echocardiography (2DE) and radionuclide ventriculography (RNV). Measured and derived indices of cardiac function were recorded before and after induction of anaesthesia, aortic cross-clamping and aortic unclamping. Induction of anaesthesia was associated with significant decreases in mean arterial pressure (MAP), pulmonary capillary wedge pressure (PCWP), cardiac index (CI) and with a highly significant decrease in left ventricular stroke work index (LVSWI). Aortic cross-clamping was associated with significant increases in MAP and systemic vascular resistance (SVR) whereas aortic unclamping was associated with a significant decrease in SVR. Preoperative LVEF, as measured by RNV and 2DE, were similar. Resting ejection fractions correlated poorly with both preoperative cardiac indices and with changes in indices of left ventricular performance seen intraoperatively. Preoperative ejection fraction determination did not predict intraoperative left ventricular performance. Preoperative exercise scanning may prove more informative.

Mood evaluation and outpatient anaesthesia. A comparison between propofol and thiopentone.

Mood state was evaluated in 40 unpremedicated patients who underwent minor gynaecological surgery, before and up to 4 hours after, anaesthesia induced with either propofol 2.5 mg/kg or thiopentone 5 mg/kg. Assessments were made by a self-report technique, the profile of mood states method. The results indicate that mood state was less affected postoperatively in patients induced with propofol than with thiopentone. The overall impression of the investigators was that propofol patients had a definite sense of well-being after anaesthesia.

Recovery from outpatient anaesthesia: a comparison of incremental propofol and propofol-isoflurane.

Propofol was used to induce anaesthesia in 60 patients undergoing minor outpatient gynaecological procedures. Maintenance was with 66% nitrous oxide in oxygen, plus either isoflurane or 10-mg increments of propofol. Recovery was assessed using both clinical and psychomotor criteria and the results compared with those obtained in a non-anaesthetized control group. As far as the two test groups were concerned, initial recovery was more rapid in the incremental propofol group but, by 1 h after surgery, there were no differences between all three groups.

A comparison of propofol and methohexitone as induction agents for day case isoflurane anaesthesia.

The induction and recovery characteristics of equivalent doses of propofol and methohexitone were compared in 50 patients undergoing day case isoflurane anaesthesia. Propofol induction was smoother but was associated with greater cardiorespiratory depression. Both the speed and quality of recovery were superior with propofol compared with methohexitone.