Research Articles (Anaesthesiology and Critical Care)
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- ItemAnaesthetic induction with propofol: How much? How fast? How slow? What determines anesthetic induction dose? It’s the Front-End Kinetics, Doctor!(Medpharm Publications, 2019) Coetzee, J. F.ENGLISH ABSTRACT: It has long been realised that linear dosing according to total body weight (TBW) results in overdosing obese patients and under-dosing small children. Injected drug doses calculated on a mg.kg-1 body weight basis work well only for patients of normal habitus. As long ago as 1969, in a study of induction doses of thiopentone, ulfsohn and Joshi2 concluded that thiopentone was better administered according to lean body mass (LBM) than to TBW. They reasoned that endomorphic somatotypes required less thiopentone than mesomorphs and ectomorphs of the same TBW, because they had less LBM. They pointed out that there is a strong association between LBM, cardiac output and basal metabolic rate, and suggested that the LBM contained the “pharmacologically active mass”. Obese patients can perhaps be loosely regarded as ordinary individuals entrapped in a cocoon of fat into which hardly any injected drug is distributed. However the LBM of obese persons also increases as they accumulate fat, mainly due to increased muscle mass, as well as enlargement of other organs and blood volume. The dilemma is that LBM does not increase at the same rate as the increase in fat. Thus, although we know that they need more drug than normal-weight patients, how much more is often uncertain.
- ItemAnaesthetic management of a three-month-old baby for cervical limited dorsal myeloschisis repair using propofol and alfentanil infusions guided by pharmacokinetic simulation software : case report(Medpharm Publications, 2019) Coetzee, E.; Gray, R.; Hollmann, C.; Enslin, N. J. M.; Coetzee, J. F.ENGLISH ABSTRACT: We present an uncommon case of limited dorsal myeloschisis in a 3-month-old infant requiring repair guided by intraoperative neuromonitoring (IONM) and therefore avoidance of volatile anaesthetic agents. The case presented challenges in positioning, airway management, a lack of age appropriate pharmacokinetic models in target-controlled infusion (TCI) syringe pumps and unavailability of remifentanil, considered to be an essential drug in this setting. We overcame these challenges using manually controlled infusions of propofol and alfentanil guided by pharmacokinetic simulation software (Stelsim).
- ItemSkin disinfection practice before skin anaesthesia, prior to neuraxial blockade : a survey of government hospital practices in South Africa(Medpharm Publications, 2019) Coetzee, D. F.; Senekal, A.; Scheepers, P. A.ENGLISH ABSTRACT: Infectious complications following neuraxial block, although being of low incidence, may lead to morbidity and mortality. Two common methods utilised for skin disinfection before skin anaesthesia prior to a neuraxial block are the isopropanol only method (isopropanol method) and the full aseptic technique (classic method). The objective of this study was to survey government-employed South African anaesthesiologists’ preference regarding the disinfection practices before the administration of local anaesthetic agents to the skin prior to the performance of a neuraxial block. Methods: Ethics approval was obtained prior to commencing the study. An electronic, web-based questionnaire in the form of a survey was distributed to various anaesthetic departments in various government teaching hospitals in South Africa. Descriptive statistics were used on the raw data using the Fisher exact test to measure associations between the different categorical variables. Results: A significant response rate of 60.3% was achieved. Regarding subarachnoid blocks, more than half of the participants (52.0%) that participated in the survey utilise the isopropanol method whereas less than half of the participants utilise the isopropanol method when performing an epidural block. Close to 75% of participants with zero to five years anaesthetic experience prefer the isopropanol method whilst only 20.9% of anaesthetists with more than ten years’ experience prefer the isopropanol method when performing a subarachnoid block (p < 0.01). Conclusion: Both methods described in this study (classic and isopropanol methods) are practised commonly by the participants in the survey and neither the classic nor the isopropanol method dominates. Local guidelines need to address the technique used to disinfect the skin before the administration of the local anaesthetic agent to the skin prior to performing a neuraxial block.
- ItemInduction of anaesthesia with propofol according to the adjusted ideal body mass in obese and nonobese patients : an observational study(Taylor & Francis Group, 2019) Smith, F. J.; Jurgens, F. X.; Coetzee, J. F.; Becker, P. J.ENGLISH ABSTRACT: Obesity changes body composition including fat free mass (FFM), regarded as the “pharmacologically active mass”. Scaling drug doses to obese patients by total body mass (TBM) results in overdose. We aimed to determine the success rate of inducing anaesthesia in normal, overweight and obese patients with propofol, using an adjusted body mass scalar (ABM), which embodies the increased FFM of obese patients. Methods: Ninety-six patients were divided into three groups according to body mass index (BMI): normal, overweight and obese. Propofol 2 mg/kg ABM was administered according to the equation: ABM = IBM + 0.4(TBM – IBM), where IBM = ideal body mass. Induction success was assessed clinically and by electroencephalographic spectral entropy. Results: The groups were similar regarding gender, age, height and IBM. One patient was morbidly obese (BMI = 44). State entropy (SE) decreased to < 60 in 33/33, 28/29 and 33/34 patients in the normal-weight, overweight and obese groups respectively, an overall success rate of 97.5% (95% confidence interval 92.7% to 99.4%). Median lowest achieved SE values and median times that SE remained < 60 did not differ between groups, however the individual values ranged widely in all three groups. Induction failed in the two patients whose SE did not decrease to < 60 (one overweight and one obese). Conclusions: The ABM-based propofol induction dose has a high success rate in normal, overweight and obese patients. Further studies are required to determine the feasibility among morbidly obese patients.
- ItemAn audit of the labour epidural analgesia service at a regional hospital in Gauteng Province, South Africa(Health and Medical Publishing Group, 2018) Leonard, T. G. A.; Perrie, H.; Scribante, J.; Chetty, S.Background. Neuraxial analgesia in the form of a labour epidural has been shown to be the most effective analgesic strategy for the labouring mother. In developed countries, data are readily available as to the number of women receiving labour epidural analgesia, as well as the complication rates of labour epidurals. However, data for South Africa (SA) on labour epidural analgesia services are limited, and there were no published data for Rahima Moosa Mother and Child Hospital (RMMCH), Johannesburg, SA. Objective. To describe the labour epidural analgesia service at RMMCH over the period of 1 year. Methods. A retrospective audit using consecutive convenience sampling was done reviewing all epidural records at RMMCH from 1 January to 31 December 2014. Results. During the study period, labour epidural analgesia was administered for 187 (1.6%) of 11 853 deliveries. Epidural records were collected for all administered labour epidurals. The most common indications documented were labour analgesia (41.7%) and primigravida (28.9%). Labour epidurals were not administered for specific medical conditions. The incidence of complications was 22.6%, and these were minor and self-limiting. Hypotension was the most common complication (12.3%). Patient satisfaction with labour epidural analgesia, where documented, was high (98.4%). Conclusion. This audit revealed a low incidence of labour epidural analgesia at RMMCH during the study period. The incidence of complications was in keeping with that seen in developed countries. Poor documentation was noted to be a problem.