Simulation, human factors and defence anaesthesia.

Simulation in healthcare has come a long way since it's beginnings in the 1960s. Not only has the sophistication of simulator design increased, but the educational concepts of simulation have become much clearer. One particularly important area is that of non-technical skills (NTS) which has been developed from similar concepts in the aviation and nuclear industries. NTS models have been developed for anaesthetists and more recently for surgeons too. This has clear value for surgical team working and the recently developed Military Operational Surgical Training (MOST) course uses simulation and NTS to improve such team working. The scope for simulation in Defence medicine and anaesthesia does not stop here. Uses of simulation include pre-deployment training of hospital teams as well as Medical Emergency Response Team (MERT) and Critical Care Air Support Team (CCAST) staff. Future projects include developing Role 1 pre-deployment training. There is enormous scope for development in this important growth area of education and training.

The Triservice Anaesthetic Apparatus: a review.

The Triservice Anaesthetic Apparatus was designed around 30 years ago as a robust and highly portable anaesthesia delivery system for medical support to airborne operations and it has been the core anaesthesia system for the Defence Medical Services since then. Over this period there have been a number of equipment changes but issues remain which are in part mitigated by recent training developments. This article reviews these changes and developments and considers the future of this equipment.

Comparison of the haemodynamic effects of dobutamine with enoximone after open heart surgery in small children.

We have studied 28 children (mean age 13.6 months) undergoing elective cardiac surgery involving a myocardial ischaemic time greater than 60 min. Thirteen received phenoxybenzamine 1 mg kg-1 before cardiopulmonary bypass (CPB) and dobutamine 10 micrograms kg-1 min-1 before discontinuation of CPB; 15 received enoximone 0.5 mg kg-1 followed by an infusion of 10 micrograms kg-1 min-1 before discontinuation of CPB. Haemodynamic variables were measured at intervals for 6 h after CPB. Two patients in each group required additional inotropic support with adrenaline. Heart rates, right and left atrial pressures, mean pulmonary artery pressures and systemic and pulmonary vascular resistance indices were similar in the two groups. Mean arterial pressure was significantly greater in those receiving dobutamine (61.3 (SD 7.6) mm Hg) compared with enoximone (56.2 (5.3) mm Hg) (P < 0.05). Differences in cardiac index (thermodilution) (dobutamine group 2.92 (0.62) litre min-1 m-2; enoximone group 2.55 (0.55) litre min-1 m-2) and left ventricular stroke work index (dobutamine group 13.1 (4.7) g m beat-1 m-2; enoximone group 10.4 (2.7) g m beat-1 m-2) were not statistically significant. Enoximone may be used successfully in these patients to assist discontinuation of CPB and maintain an acceptable haemodynamic state in the early postoperative period but, when used alone, conferred no advantage compared with the combination of dobutamine and phenoxybenzamine.

Haemodynamic effects and comparison of enoximone, dobutamine and dopamine following mitral valve surgery.

Mitral valve surgery may be complicated by a post-operative low output state requiring inotropic support, and a wide variety of factors may influence the choice of agents used to treat this condition. The authors have examined and compared the haemodynamic effects of the highly specific phosphodiesterase inhibitor enoximone, and the adrenergic agents dobutamine and dopamine in patients undergoing mitral valve surgery. Enoximone, 0.5 mg kg-1 bolus, followed by a continuous infusion of 5 micrograms kg-1 min-1, was compared against dobutamine, 7 micrograms kg-1 min-1, and dopamine, 5 micrograms kg-1 min-1, with the protocol allowing for an increase in the infusion rate by a factor of two if clinical and haemodynamic measurements indicated. All 25 patients receiving enoximone were successfully weaned from cardiopulmonary bypass at the first attempt, with significant increases in cardiac index and stroke index, combined with little or no change in heart rate or pulmonary artery pressures and a highly significant reduction in systemic vascular resistance, and a reduction in mean arterial pressure. Three of the 25 patients receiving dobutamine were withdrawn from the study because of inadequate haemodynamic response, while the remaining 22 patients demonstrated significant increases in heart rate, cardiac index and stroke index, with a reduction in systemic vascular resistance. Nine of the 25 patients receiving dopamine failed to respond adequately, while the remaining 16 demonstrated an increase in heart rate and cardiac index but with little change in stroke index and a modest reduction in systemic vascular resistance. Enoximone has been shown to be a highly effective first-line inotrope in patients following mitral valve surgery with significant advantages over dobutamine and dopamine.

Metabolic effects of dobutamine in normal man.

1. Dobutamine in 5% (w/v) D-glucose was infused at sequential doses of 2, 5 and 10 micrograms min-1 kg-1, 45 min at each dose, into eight healthy male subjects, and the effects were compared with those produced by infusion of the corresponding volumes of 5% (w/v) D-glucose alone. 2. The energy expenditure increased and was 33% higher than control (P less than 0.001) at 10 micrograms of dobutamine min-1 kg-1. The respiratory exchange ratio decreased from 0.85 (SEM 0.02) before infusion to 0.80 (SEM 0.01) at 10 micrograms of dobutamine min-1 kg-1, but did not alter during the placebo infusion (P less than 0.001). 3. Plasma noradrenaline concentrations were lower during the dobutamine infusion compared with during the infusion of D-glucose alone (P less than 0.025). Plasma dopamine concentrations remained below 0.1 nmol/l throughout both infusions. 4. Compared with during the placebo infusion, the blood glucose concentration decreased (P less than 0.001), the plasma glycerol and free fatty acid concentrations increased by 150 and 225%, respectively (both P less than 0.001), and the plasma potassium concentration decreased from 3.8 (SEM 0.07) to 3.6 (SEM 0.04) mmol/l (P less than 0.01) during dobutamine infusion. The plasma insulin concentration increased at 2 and 5 micrograms of dobutamine min-1 kg-1 (P less than 0.001) with no further rise at 10 micrograms of dobutamine min-1 kg-1. 5. Compared with during the placebo infusion, the systolic and diastolic blood pressures and the heart rate increased during dobutamine infusion (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)