Isobolographic analysis of the hypnotic interaction between propofol and thiopental

Introduction: Giving two intravenous anaesthetic agents simultaneously generally results in an additive effect. The aim of this study was to investigate the interaction between propofol and thiopental when given to patients who have had sedative premedication. Methods: Fifty patients were admitted into the study. All patients received oral midazolam 3.75 mg and intravenous fentanyl 100 mg before induction of anaesthesia. Twenty patients received an infusion of either propofol or thiopental while 30 patients received an infusion of an admixture of both drugs. Isobolographic analysis was used to determine the interaction between the two drugs. Results: The interaction between propofol and thiopental was additive. The average dose at loss of the eyelash reflex for propofol and thiopental was 0.71 mg kg-1 and 1.54 mg kg-1 respectively. Premedication decreased the induction dose by 38.2%. Conclusion: Propofol and thiopental interact in an additive fashion when given at induction of anaesthesia

Peri-operative blood pressure changes in normotensive and hypertensive patients

Controversy surrounds the acceptance of hypertension as an independent risk factor for anaesthesia. In an attempt to identify variables that are associated with increased haemodynamic instability during surgery, the blood pressure profiles of 128 patients were analysed. The two variables that contributed most to the instability were pre-operative control of blood pressure and anaesthetic technique. To reduce the fluctuation in blood pressure, it is advisable for patients to be given a regional anaesthetic. Current therapy for hypertension appears to exaggerate the depressant effects of anaesthetic drugs. Care must be taken not only to prevent hypertensive episodes during surgery, but also hypotensio

Automation of anaesthesia: a review on multivariable control

Anaesthesia is a multivariable problem where a combination of drugs are used to induce desired hypnotic, analgesia and immobility states. The automation of anaesthesia may improve the safety and cost-effectiveness of anaesthesia. However, the realization of a safe and reliable multivariable closed-loop control of anaesthesia is yet to be achieved due to a manifold of challenges. In this paper, several significant challenges in automation of anaesthesia are discussed, namely model uncertainty, controlled variables, closed-loop application and dependability. The increasingly reliable measurement device, robust and adaptive controller, and better fault tolerance strategy are paving the way for automation of anaesthesia

Enteral nutrition in 6 Malaysian intensive care units: a point prevalence study of prescription practices

Introduction: Enteral nutrition (EN) is the first line of nutrition therapy for critically ill patients with an intact gastrointestinal tract. Even though intensive care units (ICUs) generally have established feeding protocols, prescribing practices to achieve nutrition goal is still widely variable among intensive care practitioners. The aim of this study was mainly to investigate commonly prescribed types and energy concentration in EN formulations including protein prescription. Materials and methods: This was an observational, point prevalence study, involving six level 3 ICUs in Malaysia. All patients aged type of EN formulation and protein prescription recorded. RESULTS: A total of 109 patients were included in the analysis out of which 78% of them were mechanically ventilated. At the point of the study, more than 16 years of age in the participating ICUs on the 11th of October 2016 were enrolled in this study and 71.5% (78/109) received EN. Among the EN group, 68% (53/78) received standard formulation feeds (1kcal/ml) while the rest received energy dense formulation (>1kcal/ml). Fluid restriction was the main indication for energy dense formulation prescription, occurring in almost all (24/25) of the patients. There was no report of feeding intolerance. Only 2/109 received parenteral nutrition (PN) giving the EN to PN ratio of 30:1. The mean protein prescription was 0.9g/kg (SD± 0.4). Conclusion: Prescription of EN was 30 times more frequent than PN in these ICUs. In those receiving EN, standard formulation feed was 3 times more commonly prescribed than energy dense feeds with fluid restriction being the main indication of the latter. Protein prescription was less than the guideline recommendation