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Background: Blood warming poses a challenge for healthcare workers in a resource-constrained setting due to financial limitations. Various blood-warming methods have been studied, but to our knowledge, none have investigated inline gravitational blood warming using a preheated water bath. We aimed to test the efficiency of an improvised blood warmer (named the Khaya-warmer) to warm cold packed red blood cells (PRBC) to a mean temperature of 35°C, utilising consumables readily available in a resource-constrained setting. The primary outcome was the outflow temperature-time profile; secondary outcomes included flow rates and cost comparisons with standard methods. Methods: This was a laboratory-based, experimental, proof-of-concept study. We ran 20 cold PRBC units through extended blood transfusion lines, each immersed in a 1 000 ml water bath preheated to 46°C. Using a 4-probe electronic thermometer, we measured the following temperatures: ambient, PRBC bag, water bath and outflow. Results: Mean outflow temperature was 35.2°C (95% CI 35.1-35.4); mean emptying time 9.0 minutes (95% CI 8.7-10.2) with a mean flow rate of 25.4 ml.min-1 (95% CI 24.1-26.6). Conclusion: The Khaya-warmer proved to be effective in safely warming cold PRBC units to a mean temperature of 35.2°C using a cost-effective method. Future studies include investigating various flow rates using a pressure bag or a flow regulating device, and to replace the preheated water bath with a thermally insulated flask. [ABSTRACT FROM AUTHOR]

Introduction: The first commercially available target-controlled infusion pump, the "Diprifusor", employed a "Marsh" pharmacokinetic-pharmacodynamic parameter set, and this model (the Diprifusor-Marsh model) is also available in several of today's pumps. However, it is unsuited for effect-site, target-controlled infusions (Ce-TCI) because it assumes slow transfer between blood and the effect-site (ke0 = 0.26 min-1). We hypothesised that a faster ke0 of 1.21 min-1 (Adjusted-Marsh model) for Ce-TCI would result in hypnotic effects equivalent to that of the Schnider parameter set (Schnider model). Methods: We replicated a previously published study that demonstrated the Diprifusor-Marsh model's unsuitability for Ce-TCI. We randomised 40 unpremedicated young adults into two groups to receive Ce-TCI, employing either the Schnider model or the Adjusted-Marsh model. We infused propofol at 3 000 mg.hour-1, while running a pharmacokinetic simulation and recording the electroencephalographic bispectral index (BIS) electronically. At loss of consciousness (LOC), indicated by a syringe-drop, we converted the infusion to Ce-TCI, targeting the effect-site concentration (Ce) observed at LOC, for 20 minutes. We regarded a difference of 10 BIS-units as clinically important. Results: There were no statistically significant differences between the group medians regarding time-to-LOC, induction-dose, BIS at LOC and Ce-target. BIS decreased monotonically in both groups from a median of 78.5 at LOC to a steady-state median (25-27) at 15 minutes. The BIS of the Adjusted-Marsh model group closely followed the BIS of the Schnider model group. At steady state, the median BIS difference (95% CI) was -0.3 (-5.7 to 5.3), which was within the predefined interval for declaring equivalence. The Schnider model group's mean BIS at steady state did not differ from that of the previous study's Schnider model group. Conclusion: Reasons for the progressive BIS decrease to lower than expected values include delayed response-times by the BIS monitor, Ce overshoot explained by front-end kinetics, neural inertia and the choice of surrogate LOC indicator. We conclude that Ce-TCI using the Adjusted-Marsh parameter set results in equivalent hypnotic effects to those of the Schnider model, with the proviso that this may apply only to young adults of normal body habitus. [ABSTRACT FROM AUTHOR]

Introduction: The first commercially available target-controlled infusion pump, the "Diprifusor", employed a "Marsh" pharmacokinetic-pharmacodynamic parameter set, and this model (the Diprifusor-Marsh model) is also available in several of today's pumps. However, it is unsuited for effect-site, target-controlled infusions (Ce-TCI) because it assumes slow transfer between blood and the effect-site (ke0 = 0.26 min-1). We hypothesised that a faster ke0 of 1.21 min-1 (Adjusted-Marsh model) for Ce-TCI would result in hypnotic effects equivalent to that of the Schnider parameter set (Schnider model). Methods: We replicated a previously published study that demonstrated the Diprifusor-Marsh model's unsuitability for Ce-TCI. We randomised 40 unpremedicated young adults into two groups to receive Ce-TCI, employing either the Schnider model or the Adjusted-Marsh model. We infused propofol at 3 000 mg.hour-1, while running a pharmacokinetic simulation and recording the electroencephalographic bispectral index (BIS) electronically. At loss of consciousness (LOC), indicated by a syringe-drop, we converted the infusion to Ce-TCI, targeting the effect-site concentration (Ce) observed at LOC, for 20 minutes. We regarded a difference of 10 BIS-units as clinically important. Results: There were no statistically significant differences between the group medians regarding time-to-LOC, induction-dose, BIS at LOC and Ce-target. BIS decreased monotonically in both groups from a median of 78.5 at LOC to a steady-state median (25-27) at 15 minutes. The BIS of the Adjusted-Marsh model group closely followed the BIS of the Schnider model group. At steady state, the median BIS difference (95% CI) was -0.3 (-5.7 to 5.3), which was within the predefined interval for declaring equivalence. The Schnider model group's mean BIS at steady state did not differ from that of the previous study's Schnider model group. Conclusion: Reasons for the progressive BIS decrease to lower than expected values include delayed response-times by the BIS monitor, Ce overshoot explained by front-end kinetics, neural inertia and the choice of surrogate LOC indicator. We conclude that Ce-TCI using the Adjusted-Marsh parameter set results in equivalent hypnotic effects to those of the Schnider model, with the proviso that this may apply only to young adults of normal body habitus. [ABSTRACT FROM AUTHOR]

Introduction: The first commercially available target-controlled infusion pump, the "Diprifusor", employed a "Marsh" pharmacokinetic-pharmacodynamic parameter set, and this model (the Diprifusor-Marsh model) is also available in several of today's pumps. However, it is unsuited for effect-site, target-controlled infusions (Ce-TCI) because it assumes slow transfer between blood and the effect-site (ke0 = 0.26 min-1). We hypothesised that a faster ke0 of 1.21 min-1 (Adjusted-Marsh model) for Ce-TCI would result in hypnotic effects equivalent to that of the Schnider parameter set (Schnider model). Methods: We replicated a previously published study that demonstrated the Diprifusor-Marsh model's unsuitability for Ce-TCI. We randomised 40 unpremedicated young adults into two groups to receive Ce-TCI, employing either the Schnider model or the Adjusted-Marsh model. We infused propofol at 3 000 mg.hour-1, while running a pharmacokinetic simulation and recording the electroencephalographic bispectral index (BIS) electronically. At loss of consciousness (LOC), indicated by a syringe-drop, we converted the infusion to Ce-TCI, targeting the effect-site concentration (Ce) observed at LOC, for 20 minutes. We regarded a difference of 10 BIS-units as clinically important. Results: There were no statistically significant differences between the group medians regarding time-to-LOC, induction-dose, BIS at LOC and Ce-target. BIS decreased monotonically in both groups from a median of 78.5 at LOC to a steady-state median (25-27) at 15 minutes. The BIS of the Adjusted-Marsh model group closely followed the BIS of the Schnider model group. At steady state, the median BIS difference (95% CI) was -0.3 (-5.7 to 5.3), which was within the predefined interval for declaring equivalence. The Schnider model group's mean BIS at steady state did not differ from that of the previous study's Schnider model group. Conclusion: Reasons for the progressive BIS decrease to lower than expected values include delayed response-times by the BIS monitor, Ce overshoot explained by front-end kinetics, neural inertia and the choice of surrogate LOC indicator. We conclude that Ce-TCI using the Adjusted-Marsh parameter set results in equivalent hypnotic effects to those of the Schnider model, with the proviso that this may apply only to young adults of normal body habitus. [ABSTRACT FROM AUTHOR]

Introduction: The purpose of this two-part study was to determine the prevalence and severity of the burnout syndrome among South African anaesthetists working in the public and private sectors, and to identify areas of work-life (AWLs) that predispose to burnout. We reported our burnout findings in Part 1.1 In this paper (Part 2) we report on the AWLs. Methods: Invitations were e-mailed to 1 852 SASA members, requesting responses to a validated questionnaire, the Areas of Worklife Survey (Mindgarden Inc. Menlo Park, USA). The questionnaire results in scores for six AWLs that impact on the development of the burnout syndrome, namely workload, control, reward, community, fairness and values. Results: 189 public sector and 309 private sector anaesthetists responded. 85% of public sector respondents worked in academic hospitals. The values AWL could not be properly assessed due to respondents' misinterpretations regarding that particular item. Compared to private sector, public sector anaesthetists had lower (i.e. more adverse) median scores for five AWLs. Greater proportions of public sector anaesthetists had low scores for the five AWLs. Correspondingly, smaller proportions of public sector anaesthetists had high (i.e. favourable) scores for workload, control, reward, and fairness. Multivariable least squares regression analysis identified the following significant explanatory variables for the following burnout dimensions: For emotional exhaustion these were workload, reward, community and control. For cynicism they were workload, reward, control, gender and years of experience. Predictors for efficacy were reward, community, control and years of experience. Logistic regression analysis included workload, reward and control AWL as explanatory variables for a clinical diagnosis of burnout with workload the dominant variable. Conclusions: Public sector anaesthetists experience more adverse AWLs than those in private practice. The most important factor appears to be excessive workload. Additionally, the reward, community and control AWLs are important determinants of anaesthetists' psychological relationships with their work. [ABSTRACT FROM AUTHOR]

Background: Burnout is a psychological syndrome that develops in response to chronic job-related stressors. Its three predominant manifestations are emotional exhaustion, cynicism, and feelings of ineffectiveness and unfulfillment (low efficacy). Our study objectives were to establish the prevalence and severity of burnout among South African anaesthetists and to compare the results with previous studies. We also identified areas of work-life that predispose to burnout and we report these results in a separate paper (Part 2).1 Methods: We e-mailed invitations to 1 852 SASA members, requesting responses to two validated questionnaires, the Maslach Burnout Inventory and the Areas of Worklife Scale. We categorised respondents according to the "Emotional Exhaustion+1" principle, whereby a person is regarded as being clinically burned-out if he/she has a a high score for emotional exhaustion, plus either a high cynicism score or a low efficacy score. High scores for all three dimensions defined "extreme burnout". Results: 189 public sector and 309 private sector anaesthetists responded. 85% of public sector respondents worked in academic hospitals. Compared to those in private practice, public sector anaesthetists exhibited a greater prevalence and severity of burnout. This was manifested by: (1) more adverse scores for all three burnout dimensions; (2) a greater prevalence of clinically diagnosable burnout (36.5% vs. 14.2%) as well as "extreme burnout" (17.5% vs. 6.5%). Public sector anaesthetists experienced more burnout than in other countries. Conclusions: The prevalence of burnout is unacceptably high among South African anaesthesia providers, particularly in public hospitals. This poses an immediate threat to both anaesthetists' mental and physical health and to patient safety. The severity and prevalence in teaching institutions jeopardises the current effectiveness and future sustainability of the South African healthcare system. [ABSTRACT FROM AUTHOR]

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). [ABSTRACT FROM AUTHOR]

Background: 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. [ABSTRACT FROM AUTHOR]

The article focuses on dose scaling in anaesthesia for the morbidly obese. Topics discussed include impact of linear dosing according to total body weight results in overdosing the obese and underdosing small children, the study "Influence of obesity on propofol pharmacokinetics: derivation of a pharmacokinetic model" by LI Cortinez and others and use of using dual-energy X-ray absorptiometry for measurement of fat-free mass. Also discusses the allometric scaling as an alternate method.