Anaesthesia
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Randomized Controlled Trial
The cardiovascular effects of normobaric hyperoxia in patients with heart rate fixed by permanent pacemaker.
To investigate whether the established reductions in heart rate and cardiac output with hyperoxia in humans are primary effects or secondary to increases in systemic vascular resistance, we paced the hearts of nine patients with permanent pacemakers at a fixed rate when breathing either medical air (inspired O(2) fraction 0.21) or oxygen (inspired O(2) fraction 0.80) in a randomised, double-blind fashion. A thoracic bio-impedance machine was used to measure heart rate, stroke volume and blood pressure and calculate cardiac index and systemic vascular resistance index. Oxygen caused no change in cardiac index (p = 0.18), stroke index (p = 0.44) or blood pressure (p = 0.52) but caused a small (5.5%) increase in systemic vascular resistance index (p = 0.03). This suggests that hyperoxia has no direct myocardial depressant effects, but that the changes in cardiac output reported in previous studies are secondary to changes in systemic vascular resistance.
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One hundred and seventy-four Chinese gynaecology patients were studied for the impact of A118G polymorphism in the micro-opioid receptor gene (OPRM1) on pain sensitivity and postoperative fentanyl consumption. Pre-operatively, the pain threshold and pain tolerance threshold were measured using electrical stimulation. A118G polymorphism was genotyped using the polymerase chain reaction-restriction fragment length polymorphism method. ⋯ Fentanyl consumption was also significantly different in patients with different OPRM1 genotypes (homozygotes for 118G consumed more than did heterozygotes or homozygotes for 118A). Fentanyl consumption increased in accordance with the number of 118G alleles. We conclude that OPRM1 gene analysis may help predict individual opioid sensitivity and so optimise postoperative pain control.
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Randomized Controlled Trial Comparative Study
Effect of intra-operative pressure support vs pressure controlled ventilation on oxygenation and lung function in moderately obese adults.
Obesity impairs peri-operative lung function. To evaluate the impact of pressure support ventilation vs pressure controlled ventilation in moderately obese adults upon early postoperative lung function, we randomly assigned 68 moderately obese patients (body mass index 25-35 kg x m(-2)) undergoing minor surgery to receive intra-operative ventilation either with pressure support or pressure controlled ventilation. ⋯ Postoperatively, the pressure support ventilation group also had better lung function and oxygenation values than did the pressure controlled ventilation group (p < 0.005). We conclude that pressure support ventilation better maintains lung function than pressure controlled ventilation in moderately overweight patients scheduled for minor surgery.
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Goal-directed coagulation therapy is essential in the management of trauma patients with severe bleeding. Due to the complex nature of coagulation disorders in trauma, a quick and reliable diagnostic tool is essential. We report a severely injured multiple trauma patient who received haemostatic therapy with coagulation factor concentrates, guided by rotational thromboelastometry (ROTEM). ⋯ This approach enabled extended emergency hemihepatectomy to be performed without using fresh frozen plasma. As the EXTEM maximum clot firmness showed good clot quality, no platelets were transfused despite low platelet counts. This case shows the potential success of treatment using both fibrinogen concentrate and prothrombin complex concentrate, not only in restoring haemostasis but also in minimising requirement for transfusion of allogeneic blood products.