Measurement of cardiac output using Physio Flow with different positions of electrode placement.

INTRODUCTION: Physio Flow is a non-invasive impedance cardiograph device that measures cardiac output. Recommended electrode placements involve six electrodes, including two near the xiphisternum (Z3 and Z4/ ECG3/neutral). This study aims to evaluate if changing the positions of these two leads to the left fourth and fifth intercostal spaces along the mid-axillary line results in a change in the cardiac output measurement. METHODS: This was a prospective, controlled, crossover, paired study of 30 patients where electrodes were placed in the recommended positions and cardiac output (CO1) obtained after two minutes. The second cardiac output (CO2) was then obtained with the electrodes Z3 and Z4/ECG3/neutral repositioned at the left mid-axillary line at the fourth and fifth intercostal spaces. The final step involved switching the Z3 and Z4/ECG3/neutral leads back to the recommended position and the cardiac output (CO3) was measured. RESULTS: The average of the initial and third readings (COave) was compared with the measured CO2 and analysed. The regression equation was: CO at the proposed site (CO2) = COave at the recommended site + 0.058. The paired samples correlation was 0.995. Within the 95 percent limits of agreement, the bias with CO measured at the proposed site of electrode placement was 0.046 L/min with the limits at -0.24 L/min and 0.34 L/min. The mean difference was 0.86% of the average CO. CONCLUSION: A small positive bias was demonstrated when Physio Flow measurements were taken with the leads Z3 and Z4/ECG3/neutral placed in the mid-axillary line fourth and fifth intercostal spaces.

Intraoperative anaesthetic management of the liver transplant patient.

Orthotopic liver transplantation has become an established method of treating end-stage liver disease. Anaesthesia for patients undergoing this procedure can be complicated because end-stage liver disease is often associated with dysfunction of other physiological systems. Rapid haemodynamic, metabolic and coagulation changes can occur intraoperatively requiring aggressive haemodynamic monitoring backed by on-line laboratory facilities. The increased understanding of the pathophysiology of the procedure and the use of dedicated rapid infusion systems and intraoperative blood salvage have helped to improve the intraoperative management of the liver transplant patient. Co-operation and communication between the blood bank, haematology, biochemistry, surgical and anaesthesia services are vital.

Extraoperative management of the liver transplant patient.

Advances in liver transplantation have made the procedure an accepted therapeutic measure for patients with end-stage liver disease. This report is based on the authors experience on the first adult liver transplant in Singapore. The anaesthetic management is a challenge as patients are in long-standing hepatic failure with derangements of cardiovascular, renal, pulmonary, central nervous, and haematological systems. Therefore, individual preoperative assessment must incorporate a thorough understanding of these pathophysiologic phenomena and their interactions with anaesthetic drugs. Similarly, the postoperative care of the recipient will require intensive critical monitoring of all vital organ, systems and aggressive intervention to support failing organ systems. The important early concerns in the immediate postoperative period (less than 72 hours) include bleeding and graft function. After the first 72 hours, if the liver is functioning and the patient is not bleeding, it is a period of repair for the organ systems which were damaged prior to or during the transplant procedure. Intravenous nutrition is begun, and the immunosuppression maintenance dose is established. During the first three weeks, most of the technical causes of graft dysfunction, sepsis, and acute rejection become apparent. The distinction between rejection and infection continues to be an enigma, and requires rapid differentiation as the modes of therapy are totally different. The role of anaesthesiologists in the extraoperative care of the liver transplant recipient involves awareness and interdisplinary communication.

Single-blind comparative analgesic and safety study of single doses of intramuscularly administered ketorolac tromethamine and pethidine hydrochloride in patients with pain following orthopaedic surgery.

Ketorolac tromethamine, a potent non-narcotic prostaglandin synthetase inhibiting analgesic was compared with pethidine for relief of moderate to severe postoperative pain. Forty-eight patients received Ketorolac 0.5 mg/kg and 52 received pethidine 1.25 mg/kg. The degree of pain prior to the administration of the drug and pain relief that followed were quantified using a vertical visual analogue scale (VAS) and monitored at hourly intervals. The safety profile was also studied by recording all adverse events noted. The mean pain (VAS) score at medication for Ketorolac was 7.04 and for pethidine 7.09. The pain relief obtained in the first four hours following administration of the drugs was similar for pethidine and Ketorolac. Although Ketorolac showed a longer sustained pain relief, time to peak analgesia after administration of this drug was slower than that after pethidine. It took 30 to 50 min for pethidine compared to 75 to 150 min for Ketorolac to achieve peak analgesia. The latter is therefore inappropriate if rapid pain relief is required. The incidence of side effects was significantly greater with pethidine (40.4%) as compared to Ketorolac (10.4%). The similar analgesic efficacy to pethidine makes Ketorolac an appropriate drug for the relief of postoperative pain especially in day surgery settings where observation following administration of the drug as in the case of pethidine can be dispensed with and patients sent home earlier because of the minimal side effects associated with its use. Caution must be exercised with the use of large doses of Ketorolac especially if the drug is used for more than 5 days to avoid serious complications like renal failure and gastrointestinal bleeding.

Combined heart-liver transplantation with extended cardiopulmonary bypass.

We report a case of combined heart and liver transplantation for familial amyloid polyneuropathy. This is the first such combined transplant performed in Asia, and differs from previously described cases, in that cardiopulmonary bypass was continued at partial flow during liver transplantation in our case. This was done in order to provide haemodynamic support to the cardiac graft and to protect it from the impending reperfusion insult that frequently accompanies liver transplantation. The utility of this management course is discussed, along with its actual and potential complications. We also describe the impact of a lung-protective ventilation strategy employed during cardiac transplantation.

Comparison of propofol and thiopentone as anaesthetic agents for electroconvulsive therapy.

Propofol and thiopentone were compared as anaesthetic agents for electroconvulsive therapy in 31 patients on four occasions in a repeated measure crossover study. Discomfort on injection was significantly more common with propofol (51.6% of anaesthetics) compared to thiopentone (1.6% of anaesthetics). The duration of seizure was shorter with propofol in both treatments but there was significant drug-time interaction. Propofol gave a milder tonus and clonus during seizure when both treatments were considered together. The increase in systolic and diastolic arterial pressures and heart rate after treatment were significantly higher with thiopentone. Apnoea was significantly longer with propofol. The times to sitting up unaided and opening the eyes on command were the same for both drugs. The ability to walk 10 m 20 minutes after anaesthesia was significantly better with propofol (p less than 0.0001).