Left ventricular volume and ejection fraction assessment with transoesophageal echocardiography: 2D vs 3D imaging.

BACKGROUND: Developments in transducer technology have enabled the use of three-dimensional transoesophageal echocardiography (3D TOE) in the operating theatre. Transthoracic echocardiography (TTE) 3D left ventricular (LV) volumes and ejection fraction (EF) agree better with magnetic resonance imaging (MRI) measurements, with less intra- and inter-observer variability compared with 2D. This has not been validated with 3D TOE. The aim of this study was to assess the bias, limits of agreement, and reproducibility of 3D TOE and 2D TOE LV volumes and EF in cardiac surgical patients. METHODS: Sixty-three patients having cardiac surgery with TOE were evaluated. LV volumes and EF were calculated using modified Simpson's method on 2D mid-oesophageal four- and two-chamber views, xPlane, and from a 3D full-volume data set. Intra- and inter-observer variability were assessed in a subset of 17 patients. RESULTS: Real-time 3D TOE volume and EF assessment was possible in 59 of the 63 patients. Median end-diastolic volumes (EDVs) as measured by 2D, xPlane, and 3D techniques were 98.5, 94, and 97 ml. Median ESVs were 38.5, 40 and 35.6 ml. Median EFs were 58, 54 and 62.2%. There were no significant pairwise differences between these measurements. The limits of agreement for all comparisons were wide, and there were no statistically significant differences between the three methods in intra- or inter-observer variability. CONCLUSION: The intraoperative use of 3D TOE to estimate LV volumes and EF has small bias compared with 2D assessments, wide limits of agreement, and no clear advantages compared with standard 2D TOE imaging in terms of LV volume and EF assessment.

Detection of cognitive decline after coronary surgery: a comparison of computerized and conventional tests.

BACKGROUND: Postoperative cognitive decline is a common complication after coronary artery bypass graft (CABG) surgery. Postoperative cognitive decline is defined on the basis of change in cognitive function detected with repeated assessments using neuropsychological tests. Therefore improvement in neuropsychological testing instruments may increase our understanding of postoperative cognitive decline. METHODS: Fifty patients undergoing CABG surgery completed both a conventional and a computerized battery of tests before and 6 days after CABG surgery. Fifty age- and education-matched controls completed the same test batteries 6 days apart. The reliability and the sensitivity to postoperative cognitive decline were computed for each battery. RESULTS: Both test batteries detected postoperative cognitive decline 6 days after CABG surgery. For the computerized battery, the reliability of the reaction times (intraclass correlation 0.89-0.92) was greater than for any test from the conventional battery (intraclass correlation 0.56-0.71), although accuracy measures were less reliable (intraclass correlation 0.61-0.89). The computerized battery detected all the cases of POCD identified by the conventional test battery and also five cases that were classified as normal by the conventional tests. CONCLUSION: Computerized tests are suitable for measuring cognitive change after CABG surgery and may detect change in a greater proportion of patients 6 days after CABG surgery than conventional neuropsychological tests.

A comparison of 0.5% ropivacaine and 0.5% bupivacaine for axillary brachial plexus anaesthesia.

The purpose of this study was to compare the use of 0.5% ropivacaine with 0.5% bupivacaine for axillary brachial plexus anaesthesia. Sixty-six patients undergoing upper limb surgery were enrolled in a double-blind, randomized, multicentre trial. Five patients were subsequently excluded for various reasons. Of the remaining patients, 30 received 40 ml of 0.5% ropivacaine and 31 received 40 ml of 0.5% bupivacaine. Brachial plexus block was performed by the axillary approach using a standardized technique with a peripheral nerve stimulator. Parameters investigated included the frequency, onset and duration of sensory and motor block, the quality of anaesthesia and the occurrence of any adverse events. The six principal nerves of the brachial plexus were studied individually. The frequency for achieving anaesthesia per nerve ranged from 70 to 90% in the ropivacaine group and 81 to 87% in the bupivacaine group. The median onset time for anaesthesia was 10 to 20 minutes with ropivacaine and 10 to 30 minutes with bupivacaine, and the median duration was 5.3 to 8.7h with ropivacaine and 6.9 to 20.3h with bupivacaine. Motor block was evaluated at the elbow, wrist and hand, and was completely achieved at a rate of 60 to 73% in the ropivacaine group and 55 to 71% in the bupivacaine group. The median duration of motor block was 6.5 to 7.5h with ropivacaine and 6.0 to 9.0h with bupivacaine. These parameters were not statistically different. The duration of partial motor block at the wrist (6.8 v 16.4h) and hand (6.7 v 12.3h) was significantly longer with bupivacaine. Ropivacaine 0.5% and bupivacaine 0.5% appeared equally efficacious as long-acting local anaesthetics for axillary brachial plexus block.

Comparison of 0.5% ropivacaine and 0.5% bupivacaine in lumbar epidural anaesthesia for lower limb orthopaedic surgery.

The purpose of this study was to compare the epidural use of 0.5% ropivacaine and 0.5% bupivacaine in patients undergoing lower limb orthopaedic surgery. In a double-blind, randomized, multi-centre study involving 67 patients, thirty-two patients received 20 ml of 0.5% ropivacaine and 35 patients received 20 ml of 0.5% bupivacaine at the L2,3 or L3,4 interspace. Parameters measured were the onset time, duration and spread of sensory block, the onset time, duration and degree of motor block, the quality of anaesthesia and the heart rate and blood pressure profile during block onset. Four patients (3 ropivacaine, 1 bupivacaine) were excluded from the study due to technical failure of the block. The onset and duration of analgesia at the T10 dermatome (median, interquartile range) was 10 (5-15) minutes and 3.5 (2.7-4.3) hours respectively for ropivacaine, and was 10 (6-15) minutes and 3.4 (2.5-3.8) hours respectively for bupivacaine. Maximum block height (median, range) was T6 (T2-T12) for ropivacaine and T6 (C7-T10) for bupivacaine. Nine patients receiving ropivacaine and eight patients receiving bupivacaine developed no apparent motor block. The incidence of complete motor block (Bromage grade 3) was low in both groups, being 4/27 for ropivacaine and 6/34 for bupivacaine. In the ropivacaine group, motor and sensory block were judged to be satisfactory in 78% of patients. In the bupivacaine group, motor and sensory block were judged to be satisfactory in 71% and 62% of patients respectively. Cardiovascular changes were similar in both groups. No statistical differences were found between the two groups regarding any of the study parameters.

A simple technique for diagnosing oesophageal intubation.

Undiagnosed oesophageal intubation during anaesthesia is a major cause of anaesthetic-related morbidity and mortality. A test was devised and evaluated to distinguish between placing an endotracheal tube in the trachea and in the oesophagus. The test involves threading a lubricated nasogastric tube through the endotracheal tube, applying continuous suction to the nasogastric tube and then attempting to withdraw the nasogastric tube. Four aspects distinguish an endotracheal tube in the trachea from one in the oesophagus: 1. the length of nasogastric tube inserted and the feel of the final obstruction to further insertion. 2. the ability to maintain unobstructed suction through the nasogastric tube, 3. the ease of withdrawal of the nasogastric tube during continuous suction, 4. the nature of any aspirate (i.e. mucus or gastric contents). An evaluation was performed on twenty patients in whom both the trachea and oesophagus were intubated simultaneously. In all twenty cases, each of the two endotracheal tubes was correctly identified as being either tracheal or oesophageal. The ability to maintain suction and the ease of withdrawal most clearly distinguished between the two positions.

Physiological changes during liver transplantation.

Thirteen patients who received liver transplants at the National Liver Transplant Unit between January 1986 and March 1987 were studied with extensive monitoring and frequent intraoperative biochemical and haematological profiles. Anaesthetic technique was standardised for all patients. Retrospective analysis of this data confirms that patient homeostasis is most disturbed at the time of revascularisation of the donor liver. In this series, revascularisation was associated with marked changes in all measured haemodynamic parameters (arterial blood pressure, cardiac index, heart rate, and filling pressures). There was also a significant fall in pH with revascularisation, followed by a gradual rise during the final phases of the operation. Potassium levels often rose sharply with revascularisation but then decreased during the rest of the operative period. Ionised calcium levels did not change significantly at any stage; however, all patients were given calcium intraoperatively. Coagulation profiles were often abnormal preoperatively. The transplant procedure was associated with further abnormalities in both coagulation and fibrinolysis. Patient temperatures were maintained at normal levels throughout the procedure.

Liver graft revascularization by donor portal vein arterialization following "no touch" donor hepatectomy.

Unsatisfactory immediate function of the transplanted liver together with technical complications contribute to a persisting early mortality for hepatic transplantation in the 20% range. We report our initial clinical experience with methods, one not previously used clinically, that resulted in uniformly well-functioning liver grafts in 11 patients and contributed to a satisfactory success rate for the procedure. Donors were heart-beating. During the donor operation all manipulations of the liver were avoided until after cold preservation, achieved by external cooling at the same time as circulatory interruption, donor exsanguination and perfusion of the liver with cold oxygenated fluid of "extracellular" type. The organs were then gently dissected. At transplantation the livers were revascularized with arterial blood shunted from the recipient iliac artery to the graft portal vein after completion of the suprahepatic IVC anastomosis. The infrahepatic IVCs and hepatic arteries were then joined, the iliac artery shunts discontinued and the portal veins joined. Total ischaemic intervals for the allografts were 3 1/2-8 (average 5). Anhepatic intervals were 1-2 1/4 (average 2). The arterio-portal shunts were operating for 18-85 (mean 46) min. Blood loss and haemodynamic, acid-base and electrolyte abnormalities at revascularization were minimal. All grafts secreted bile immediately and all parameters reflected continuing improvement of liver function thereafter. Nine patients (82%) are alive between 4 and 18 (mean 11) months after transplantation. We conclude that these methods offer effective avoidance of serious organ damage during donor hepatectomy and preservation, reduced allograft ischaemic interval and reduced recipient anhepatic time. They result in avoidance of blood loss at the time of revascularization, together with minimal haemodynamic, acid-base or biochemical changes. In addition, they allow the surgeon to perform and test all anastomoses without time constraints, provide the capability to deal with unexpected complications, and assure good early graft function.