OpenUCT :: Browsing by Subject "Anaesthesiology"

Browsing by Subject "Anaesthesiology"

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Open Access
A multicentre cross-sectional descriptive study evaluating the cardiovascular risk profile of preoperatively identified patients with hypertension
(2021) Govender, Sarisha; Rayner, Brian; Dyer, Robert
Background. The prevalence of hypertension in adults in South Africa (SA) is 35%. Hypertension is the most important modifiable risk factor for cardiovascular (CV) and chronic kidney disease (CKD) in subSaharan Africa. However, 49% of people are unaware of their blood pressure status. Screening for hypertension prior to surgery provides a unique opportunity to diagnose and treat affected individuals. Furthermore, assessing overall CV risk identifies patients at highest risk for complications, and improves the utilisation of scarce resources. Objective. To evaluate the CV risk profile of hypertensive patients in the adult population of the Western Cape Province presenting for elective non-cardiac, non-obstetric surgery. Methods. This report documents the CV risk profile of patients recruited to the HASS-2 study (Hypertension and Surgery Study 2), which was undertaken in seven Western Cape hospitals. Patients were screened for hypertension and pharmacological treatment was initiated or adjusted in patients with stages 1 and 2 disease. Stage 3 patients were referred to a physician. In the present substudy, patients with stages 1 and 2 hypertension were assessed for associated CV risk factors, the presence of target organ damage, and documented CV or kidney disease; they received an overall risk stratification according to the 2018 European Society of Cardiology and the European Society of Hypertension Guidelines. Results. Sixty-one patients with stage 1 and 12 with stage 2 hypertension were analysed. Established CV disease was present in 13.7% of the study population, and CKD (eGFR <60 ml/min) in 10.8%. Seventy-one percent of the study group had a raised body mass index, and 55.9% underlying metabolic syndrome. Prediabetes and diabetes were present in 16.1% and 14.5% respectively. According to the 2018 European guidelines, 34.7% were at moderate, 33.3% at high and 16.7% at very high risk for a CV event in the following 10 years. Conclusions. The perioperative period is a critical time during which surgeons, nurses and anaesthetists can influence patients' CV risk of adverse events. This involves appropriate screening, education and treatment. In this study population, nearly 9 out of 10 elective surgical patients with stage 1 or 2 hypertension had CV risk factors placing them at moderate to very high risk. The simultaneous assessment of these additional CV risk parameters, in addition to diagnosis and management of hypertension, may further decrease the health and financial burden in resource-limited facilities in SA, and improve CV outcomes.
Open Access
A prospective study of paediatric preoperative fasting times at Red Cross War Memorial Children's Hospital
(2021) Kouvarellis, Alison; Wilson, Graeme; Biccard, Bruce; van der Spuy, Karen
Background. Fasting for liquids and solids is recommended prior to procedures requiring anaesthesia, to reduce the risk of pulmonary aspiration. Children often experience excessive fasting, which is associated with negative physiological and behavioural consequences, and patient discomfort. The duration of preoperative fasting in children in South Africa is unknown. Objectives. The aim of this study was to determine the compliance with fasting guidelines and fasting times of children prior to elective procedures performed under anaesthesia at a paediatric hospital in Cape Town, South Africa. The primary focus was fasting for clear liquid. The study also intended to identify the most common reasons for prolonged clear liquid fasting. Methods. Over a seven-week period, we prospectively captured fasting times of consecutive patients undergoing elective surgical, medical and radiological procedures at Red Cross War Memorial Children's Hospital (RCWMCH). Measurement outcomes were defined as the period from the last clear liquid, milk or solid feed to the start of anaesthesia. For analysis of compliance with preoperative fasting guidelines, institutional preoperative fasting target limits were established based on the standard 6-4-2 hour guideline. Results. The study included 721 elective paediatric cases. The mean (SD) fasting time for clear liquids (n=585) was 8.0 (4.8) hours, with an adherence rate of 25.5% (95% confidence interval (CI) 22-29%) to the institutional target of 2 to 4 hours. The mean (SD) fasting times for breast milk (n=92), formula milk (n=116) and solid feeds (n=560) were 7.1 (2.8), 8.8 (2.8) and 13.9 (3.6) hours respectively. The factors associated with clear liquid fasting >4 hours were: inadequate fasting instructions, poor adherence to fasting orders, procedural delays and fasting to promote theatre flexibility. Conclusion. This study demonstrates that children in a South Africa hospital experience excessive fasting times prior to elective procedures. To reduce fasting durations and improve the quality of perioperative care, quality improvement (QI) interventions are required to create an adaptable fasting system which allows individualised fasting. Improving preoperative fasting times in children is the responsibility of all health care professionals in the multi-disciplinary management team.
Open Access
A randomised comparison of bolus phenylephrine and ephedrine for the management of spinal hypotension in patients with severe preeclampsia and a non-reassuring fetal heart rate trace
(2018) Adams, Samantha; Dyer, Robert A
Background: Studies in healthy patients undergoing elective caesarean delivery show that ephedrine used for spinal hypotension is associated with increased fetal acidosis compared with phenylephrine. This has not been investigated prospectively in severe preeclampsia. Methods: Patients with severe preeclampsia requiring caesarean delivery for a non- reassuring fetal heart tracing were randomised to receive bolus ephedrine (7.5-15 mg) or phenylephrine (50-100 μg) for spinal hypotension. The primary outcome was umbilical arterial base deficit. Secondary outcomes were umbilical arterial (UA) and venous (UV) pH and lactate level, venous base deficit, and Apgar scores. Results: A total of 133 women were included;; 64 required vasopressor treatment and were randomised to 2 groups of 32 with similar patient characteristics. Pre- delivery blood pressure changes were similar in the 2 groups. There was no difference in mean [SD] UA base deficit (-4.9 [3.7] vs -6.0 [4.6] mmol·L⁻¹ for ephedrine and phenylephrine respectively;; P = 0.29). Mean [SD] pH (UA and UV) and lactate levels were also similar between groups (7.25 [0.08] vs 7.22 [0.10], 7.28 [0.07] vs 7.27 [0.10], and 3.41 [2.18] vs 3.28 [2.44] mmol·L⁻¹ respectively). In addition, UV PO₂ was higher in the ephedrine group (2.8 [0.7] vs 2.4 [0.62]) kPa, P = 0.02). There was no difference in 1- or 5-minute Apgar scores, numbers of neonates with 1-minute Apgar scores < 7 (10/32 [31%] vs 12/32 [38%]), or with a pH < 7.2 (6/31 [19%] vs 8/29 [28%]). Conclusions: In patients with severe preeclampsia and fetal compromise, fetal acid-base status is independent of the use of bolus ephedrine vs phenylephrine to treat spinal hypotension.
Open Access
A systematic review of outcomes associated with withholding or continuing angiotensinconverting enzyme inhibitors (ACE-I) and angiotensin receptor blockers (ARB) prior to noncardiac surgery
(2019) Hollmann, Caryl; Biccard, Bruce
Introduction The global rate of major noncardiac surgical procedures is increasing annually, and of those patients presenting for surgery increasing numbers are taking either an angiotensin-converting enzyme inhibitor (ACE-I) or an angiotensin receptor blocker(ARB). The current recommendations whether to continue or withhold ACE-I and ARB in the perioperative period are conflicting. Previous metaanalyses have linked preoperative ACE-I /ARB therapy to the increased incidence of post induction hypotension, however have failed to correlate this with adverse patient outcomes. The aim of this meta-analysis was to determine whether continuation or withholding ACE-I or ARB therapy in the perioperative period is associated with mortality and major morbidity. Methods This meta-analysis was prospectively registered on PROSPERO (CRD42017055291). A comprehensive search of MEDLINE (PubMed), CINAHL (EBSCO host), ProQuest, Cochrane database, Scopus and Web of Science was conducted on 06 December 2016. We included adult patients >18years, on chronic ACE-I or ARB therapy who underwent noncardiac surgery, where ACE-I or ARB was either withheld or continued on the morning of surgery. Primary outcomes included all-cause mortality and major cardiac events (MACE). Secondary outcomes included the risk of congestive heart failure (CHF), acute kidney injury, stroke, intra/postoperative hypotension and the length of hospital stay (LOS). Results Following abstract review, the full text of 25 studies were retrieved, of which nine fulfilled the inclusion criteria; five were randomized control trials (RCTs) and four cohort studies. These studies included a total of 6022 patients on chronic ACE-I/ARB therapy prior to noncardiac surgery. 1816 patients withheld treatment the morning of surgery and 4206 continued their ACE-I/ARB. Preoperative demographics were similar between the two groups. Withholding ACE-I/ARB therapy was not associated with a difference in mortality (odds ratio [OR], 0.97; 95% confidence interval [CI], 0.62-1.52; I2 =0%) or MACE (OR 1.12; 95% CI 0.82-1.52; I2 =0%). Withholding therapy was however associated with significantly less intra-operative hypotension (OR 0.63 95% CI 0.47;0.85, I 2 =71%). No effect estimate could be pooled concerning length of hospital stay and CHF. Conclusions This meta-analysis did not demonstrate an association between perioperative administration of ACEI/ARB, and mortality or MACE. It did however confirm the current observation that perioperative continuation of ACE-I/ARBs is associated with an increased incidence of intra-operative hypotension. A large randomized control trial is necessary to determine the appropriate perioperative management of ACE-I and ARBs.
Open Access
Anaesthesia Preoperative Clinic (APOC) Audit
(2016) Dass, Deshandra; Nejthardt, Marcin B; Roodt, Francois
Background: Preoperative assessment clinics have been employed in many institutions to manage perioperative risks1. These clinics provide an opportunity to stratify patients on the basis of risk prior to surgery, to make timely multidisciplinary referrals where appropriate, and to prescribe medical therapies according to the current best evidence resulting, in fewer last-minute cancellations for medical reasons2 and a shorter inpatient pre-operative stay3. The Anaesthetic Pre-Operative Clinic (APOC-GSH) was introduced to Groote Schuur Hospital in 2009 with the aim of assessing and optimising high risk patients undergoing intermediate or high risk surgery. The vision of the clinic is to decrease perioperative morbidity and mortality, rationally and costconsciously investigate patients, as well as to reduce theatre cancellations of inappropriately assessed and managed patients. The clinic, together with relevant role players, attempts to risk stratify patients in making an informed decision whether the intended perioperative risks are acceptable. Patients referred to the clinic fall into two categories. Either the surgical date has been scheduled and patients are referred to APOC-GSH for optimization, or the referral is for assessment of suitability to undergo an anaesthetic and thus the treatment modality hinges on the fitness for surgery. Objective The intention of the audit is to create a database of the patients seen at APOC-GSH during 2014. Primary objectives are: 1 Referral pattern: - What proportion of patients are referred for improvement of medical condition? - What proportion of patients are referred for an assessment of operability? 2 What interventions were recommended? - What was the influence of interventions on operability and timing of surgery? - Does the clinic improve theatre efficiency by reducing cancellations of patients who required further interdisciplinary discussion and investigations? Methods: Data collection will be based on the review of APOC-GSH clerking notes and hospital patient records. The following information will be collected and entered into an Excel spread sheet: the surgical discipline referring the patient, the proposed surgery, patient co-morbidities, the lead-time from the first APOC-GSH assessment to surgery, number of visits to APOC-GSH by each patient, the investigations and additional interventions instituted at APOC-GSH. We shall also calculate the proportion of patients that would have likely been cancelled had they not attended APOC-GSH but rather been assessed by an anaesthetist the day before surgery. The record of the APOC-GSH consultation will be documented on a clerking sheet established for use within the clinic (Addendum A). The original form will be included in the patients' file and a duplicate will be stored within the access controlled Department Of Anaesthesia offices at GSH. The duplicate records will be used to obtain the information for the audit. Ethical approval will be sought from the UCT Human Research Ethics Committee for the establishment of the database and retrospective review of the APOC-GSH records on the understanding that patient records would be kept confidential and that the data obtained would be stored in a password protected spreadsheet. Access to the spreadsheet will be limited to the investigators involved and no identifiable patient details will be included. Patients will be counselled as to the nature of the study and will be expected to submit signed consent forms allowing their records to be reviewed. Patients will be informed that they will not be disadvantaged by refusal to sign the consent form and that the appropriate standard of care will still be applied. No remuneration will be provided for partaking either. Consent will be documented on the consent form specifically designed for use in the APOC-GSH. (Addendum B) Statistical analysis will be performed using an Excel® spreadsheet. Means, medians, rates and percentages will be used to describe the discrete categorical data. Output and future work The audit will provide an objective assessment of the population profile referred to APOC-GSH. It may guide future implementation of APOC-GSH protocol changes and assist with resource allocation depending on the surgical discipline requirements. Patient and surgeon satisfaction ratings may be embarked at a later stage juxtaposed against an adequate assessment in a cost and time conscious manner.
Open Access
Analgesia : a prospective audit on patient satisfaction with postoperative analgesia in a South African tertiary hospital
(2015) Van der Westhuizen, Christo; Montoya-Pelaez, L F; Dyer, Robert A
Background: The vast majority of patients will be admitted to general wards after their surgical procedures. Ward staff will provide the prescribed analgesia. The researchers would like to ascertain whether the patient population is satisfied with the analgesia that they receive. Methods: Fifty-two postoperative patients consented to taking part in a prospective audit that enquired about pain using a Numeric Rating Scale (NRS) on discharge from the theatre recovery room as well as on day one postoperatively. Additionally patients were asked to indicate whether the analgesia was 'good', 'fair' or 'poor' and were interviewed about their expectations regarding pain. Results: The mean age was 45 (SD 14) years and median surgical duration was 100 (IQR 75- 150) minutes. Mean NRS score was 3 (SD 3) on discharge from recovery as well as on day one postoperatively. 'Good' analgesia was reported by 69.2% of patients and 71.2% reported that they had less pain than expected. The median time from recovery room discharge to first dose of analgesia was 135 (IQR 65-400) minutes. Conclusion: Sixty seven per cent of patients indicated that they were satisfied with the analgesia provided. There are, however, still problems with long waiting times to first doses of analgesia. The relatively low overall pain scores and high levels of satisfaction are encouraging.
Open Access
Audit of acute limb ischaemia in a paediatric intensive care unit
(2016) Mumba, Jesse Musokota; Hodges, Owen; Thomas, Jenny
Objective:Iatrogenic acute limb ischaemia in paediatric patients is a well-recognised complication of vascular access. This retrospective review of a paediatric intensive care unit identified patients who developed iatrogenic acute limb ischaemia between January 2008 and July 2013. Methods: The medical records of inpatients diagnosed with acute limb ischaemia during the study period were reviewed. Patients with other causes of acute limb ischaemia were excluded. A descriptive analysis of demographics, primary diagnosis, type of vascular access used, affected anatomical region, clinical presentation, type of therapy, type of block, response to intervention used and outcomes was conducted. Results:A total of 28 patients presented with signs of acute limb ischaemia, of whom 28.6% were aged <30 days, 46.4 % were between one and 12 months and 25% were between one and five years old; 78.6% of the affected limbs were lower limbs. Four patients had resolution of ischaemia upon removal of the vascular access devices. 23 patients received various forms of pharmacological sympathectomy, in addition to conservative therapy. One patient had missing data on the type of sympathectomy that was done. The response to the sympathectomies was: 60.9% good, 8.7% moderate, 8.7% poor and in 21.7% no responses. Documented tissue loss related to the ischaemia occurred in six (21.4%) of the 28 patients. Conclusions: Iatrogenic acute limb ischaemia in children are usually managed without surgical intervention. Pharmacological sympathectomies lead to increased blood flow to the affected limb via vasodilatation of collateral vessels, with an added advantage of reducing ischemic pain. The improved blood flow is postulated to avoid and/or minimise the amount of tissue loss. Pharmacological sympathectomies may, thus, have a role to play in th e management of iatrogenic acute limb ischaemia in the paediatric population.
Open Access
Audit of transfusion practice during burns surgery at the Red Cross War Memorial Children's Hospital
(2017) Spies, Anri; Bester, Kotie
Rationale: Major burn surgery can be associated with significant blood loss, often requiring transfusion of blood products. In an effort to decrease aforementioned blood loss, various blood conservation strategies have been developed, rendering older formulae to predict intraoperative blood loss ineffective and outdated. Currently there are no clear guidelines on when to transfuse burn victims but, the trend is towards employing a more conservative transfusion practice in an attempt to reduce transfusion related complications. The predicament has become one of containing cost by not ordering blood unnecessarily and/or excessively, versus putting a patient at risk by not having blood available when he or she needs it. A guideline, based on haemoglobin and extent of surgery, was drawn up at the Red Cross War Memorial Children's Hospital in an effort to rationalise preoperative blood ordering. The aim of this audit was to assess how well the implemented guideline was adhered to, and how accurately the guideline predicted the need to have blood products available in theatre during burns surgeries of varying extent. Methods: After a guideline, based on expert opinion, had been drawn up and implemented, a prospective audit of practice was done from April 2014 to June 2015. Two hundred separate burn surgeries were audited. Data collected included haemoglobin levels, extent of surgery, pre-and intra-operative instructions to blood bank, and whether patients were transfused. Pre-operative instructions were compared to the guideline to test adherence, and to the ultimate need for blood to test accuracy. Additional data recorded were the adherence to surgical plan (extent of surgery). Results: Five of the 200 cases were excluded due to incomplete data, leaving 195 cases. Blood was ordered according to the guideline in 131 (67.2%) cases. There were two groups where adherence was particularly poor. In these patients the guideline suggested that only a group and screen was necessary - a category for which it would also be difficult to assess how accurately the guideline predicts the need for blood. After excluding these two groups, the preoperative instructions to the blood bank were appropriate in 119 (94.4%) of the 126 cases where the guideline was followed. Blood was ordered preoperatively in 83 of the 195 cases, but only used in 50 cases (60.2%). Of the 33 cases where blood was not used, 23 cases were not in keeping with the guideline. In 50 (83%) of the 60 cases where blood was ordered according to the guideline, it was appropriate. The performed surgery proceeded as planned in 162 (83.1%) cases. Discussion: Blood transfusion exposes the recipient to transfusion-related risks and is expensive. In an attempt to avoid these risks there has been a trend towards conservative transfusion practices. It has been shown to be cost effective and safe to employ a restrictive transfusion practice during major paediatric burn surgery. During our study period one unit of blood cost R1096,00 and a group and screen R172,00. Significant savings could therefore be incurred if blood is ordered according to the proposed guideline. Conclusion: This audit confirmed that the guideline is an appropriate one to use for preoperative ordering of blood products for burns surgery at the Red Cross War Memorial Children's Hospital.
Open Access
Coagulation in the HIV-positive pregnant patient: A thromboelastographic study
(2020) Mayeza, Slindile; Dyer, Robert A
Human immunodeficiency virus (HIV)infection is associated with haematological changes, including thrombocytopaenia. Pregnancy induces a hypercoagulable state. There are limited data on the coagulation status of women with term pregnancy and HIV receiving anti-retroviral medication. Regional anaesthesia is the technique of choice for caesarean section, and is contraindicated in a hypo-coagulable state. We therefore investigated the coagulation status of term pregnant women with HIV, presenting for elective caesarean section(CS). This was a single-centre cross-sectional observational study, using thromboelastography, comparing the coagulation status of HIV negative and -positive women with no other comorbidities, in pregnancy at term. A blood sample was taken immediately prior to spinal anaesthesia, and thromboelastography was performed within 4 minutes. In addition, platelet count, haemoglobin, and fibrinogen level were measured. Blood samples were obtained from 75 patients. There were no between-group differences in obstetric and demographic data, and no difference in platelet count. The mean (SD) fibrinogen level was higher in HIV positive women (3.9 [1.5] vs 3.5 [0.7] g/L) respectively, p=0.04. There were no significant differences in the r-time, alpha-angle, k-time, MA, or LY-30. The results of this thromboelastography study show that in asymptomatic HIV positive pregnant patients on anti-retroviral treatment, there are no significant differences in coagulation parameters when compared with HIV negative patients. This suggests that routine assessment of coagulation is unnecessary before spinal anaesthesia in patients without other co-morbidities. Further studies could demonstrate the incidence of abnormalities in coagulation or platelet function in patients with AIDS defining disease or HIV positive patients with other co-morbidities.
Open Access
A comparative study of ROTEM-EXTEM results obtained from EDTA-treated whole blood samples and Sodium Citrate-treated whole blood samples in healthy volunteers
(2016) Du Preez, Marlize; James, Michael Frank Mansel; Dyer, Robert A
Background: A number of anticoagulants are available in clinical use to preserve blood samples in liquid form until a suitable time for laboratory testing. Rotational thromboelastography is usually performed on a blood sample that has been anticoagulated with sodium citrate and then recalcified immediately prior to testing. In our institution we have had shortages of citrated Vacutainer® sample tubes. The use of a single in vitro anticoagulant promises to cut costs, simplify laboratory processes as well as limit the amount of blood drawn from patients. This together with the known problems with using citrate as an anticoagulant for viscoelastic testing (VET) prompted us to investigate the suitability of EDTA as anticoagulant for VET. Method: Blood samples from 20 healthy volunteers were divided into citrated and EDTA Vacutainer® tubes. A ROTEM EXTEM® assay was performed on each sample in both groups following the manufacturer's guidelines. Clotting time (CT), clot formation time (CFT), alpha angle (α-angle) and maximum clot firmness (MCF) results were compared. Ionised calcium concentrations were measured on each sample before and after recalcification with CaCl2 to determine if there was a significant difference in post - recalcification ionised calcium concentrations between the groups. Results: The results from the two groups were treated by Bland-Altman analysis. Apart from MCF values there was significant bias between all parameters measured in the two groups. The limits of agreement for all parameters apart from MCF were unacceptable. Conclusion: We found that ROTEM EXTEM® results from EDTA samples were not comparable to or interchangeable with those from citrated samples. The difference in results is not due to differences in ionised calcium concentration levels in the samples post-recalcification as the ionised calcium concentrations in both groups post-recalcification were adequate for coagulation. EDTA samples did show superior consistency in all parameters and may be a suitable alternative for sample preservation for VET if reference ranges can be established.
Open Access
A cost comparison of spontaneously ventilated patients: the universal anaesthesia machine as a possible cost effective alternative
(2015) Van Rensburg, G P; Nieuwveld, Robert; James, Michael Frank Mansel
Background: A new appreciation of relevant risks, as well as the increased availability of technologies that facilitate the use of regional techniques, have increased the number of patients that are allowed to breathe spontaneously during their procedures. The ever-growing caseload of surgical patients in resource poor environments demands an anaesthetic service and equipment capable of meeting with these demands. Methods: Patients were recruited to receive their general anaesthesia by means of either the Universal Anaesthesia Machine (UAM) or the standard plenum system available. Anaesthesia was administered according to a protocol and the consumption of electricity, carrier gases, volatile hypnotic agent and carbon dioxide absorbent was measured. The cost per minute was then calculated for each device respectively. Results: Our study recruited 50 patients (25 into each group) across several surgical specialties. We found that when calculated as a total South African Rand (ZAR) per minute cost (for our centre) the UAM was statistically significantly more expensive (R 0.974/min vs. R 0.459/min, p < 0,00001). We were able to derive equations to predict the cost consumption of the respective devices, allowing the use of this data in a wide array of clinical settings. Conclusion: Whilst our finding is by no means surprising, it allowed us to produce formulae by which individual centres can calculate the implications of each option using the specific costs of the various consumables available to them.
Open Access
Documentation of spinal anaesthesia technique and block level at caesarean section
(2021) Du Toit, Michiel Adriaan; van Dyk, Dominique; Dyer, Robert A
Background The ease of administration and relative safety of spinal anaesthesia has made this the preferred technique for elective and many emergency caesarean sections. Complications include incomplete sensory block, resulting in intraoperative breakthrough pain, which is commonly associated with a successful medicolegal claim. If documentation of spinal anaesthesia technique was found to be inadequate in the course of such medicolegal proceedings, it is likely that the decision would be against the anaesthetist. The purpose of this study was to evaluate documentation by anaesthetists relating to the establishment of surgical anaesthesia utilizing subarachnoid block. Methods A retrospective folder analysis was conducted at Mowbray Maternity Hospital in Cape Town, South Africa. One hundred consecutive spinal anaesthesia charts, each completed by a different anaesthetist, either a registrar or specialist, were analysed, starting December 31st, 2018, and proceeding retrospectively in time until the sample size was achieved. Results Of the 100 cases of spinal anaesthesia for caesarean section analysed, 68 were emergency and 32 elective operations. After literature review, 12 variables were identified requiring documentation, so that adequate information would be available in the event of medicolegal action. In 23% and 32% of patients respectively, 7 or 8/12 were recorded. Ninety percent of anaesthesia charts had inadequate documentation, defined as information on fewer than 10 of the specified variables. Conclusion The quality of documentation of procedure and block level during spinal anaesthesia for caesarean section was inadequate. National guidelines should be drafted and standardised to improve the quality of these records, both for quality of care and medicolegal purposes.
Open Access
Effect of a histidine-tryptophane-ketoglutarate solution on coagulation as measured by a thromboelastogram
(2016) Kabambi, Kasandji Freddy; Wilson, Graeme
Background: The Histidine-tryptophan-ketoglutarate (HTK) solution is cardioplegic solution that confers myocardial protection during periods of ischemia in heart surgery. It has the advantage of allowing a longer protection and it is especially the preferred cardioplegic solution in complex paediatric heart surgery like transposition of great vessels. This has also been used in organ transplant as a preservative solution. Recently concern has been raised over its safety because of the increased incidence of transplant failure due to thrombosis in individuals whose transplanted organ were preserved with HTK solution. The main purpose of this study was to establish whether the HTK solution in the dose and volume used for myocardial protection during paediatric heart surgical procedures increases the thrombotic risk of patients. Patient and methods: This study was an experimental study conducted at the coagulation laboratory of the department of anaesthesia of the University of Cape Town. The human research ethical committee of this university approved this study. Twenty healthy individual were recruited for this study and each one of them read and signed the consent form before being enrolled for the study. The exclusion criteria were any known coagulopathy, liver diseases, alcoholism, kidney disease and intake of any drugs known to impair the coagulation. Ten millilitre of blood was drawn from the volunteer at the coagulation laboratory. The blood was diluted with either HTK solution or St Thomas' cardioplegic solution at 9:1 ratio to mimic the hemodilution due to HTK solution in paediatric population. The effect on coagulation was assessed by means of thromboelastography run on the native blood and each dilution separately. Results: The difference in the magnitude of change from baseline in r-time between the HTK solution and Saint Thomas' solution (mean difference 0.49 min) (p 0.014) was statistically significant. There was no statistically significant change in MA between the HTK solution and St Thomas' solution (mean difference -2.13 mm) (p 0.165). Compared to native blood there were no significant change in r-time with the HTK solution (mean -0.215 min), the same with St Thomas' solution. Compared to native blood, there was significant change in maximum amplitude with the HTK solution (mean 1.38 mm) the same with St Thomas' solution (mean 3.51). Although the difference in the magnitude of in R time change between HTK solution and St Thomas' was statistically significant, it is clinically not relevant. The data did not show a trend that might become significant with large sample. All variables showed a slight tendency towards decreased coagulation in the diluted samples, but not of sufficient magnitude to be clinically important. Our goal was the use of a dilution that is clinically relevant in the context of paediatric cardiac surgery. Conclusion: The results of this study suggest the HTK solution at 10% dilution does not cause significant changes in coagulation parameters. In comparison to normal saline, there were a tendency toward hypocoagulation. More research in this field is needed to clarify the pathophysiologic pathways of thrombosis observed in these transplants.
Open Access
How does sevuflurane induction, followed by a ketamine maintenance infusion affect intraocular pressure? : establishment of a protocol for paediatric glaucoma examinations under anaesthesia
(2015) Van der Walt, Jessica Gwendoline; Roodt, Francois
Purpose: 1.To determine the effect of sevoflurane induction, followed by intravenous (IV) ketamine infusion on intraocular pressure (IOP) in the paediatric glaucoma population. 2. To establish the earliest time point at which IOP measurement most closely resembles awake values. Methods: A prospective, descriptive study of the IOP changes occurring in 25 children requiring IOP measurements at our institution. A standardised anaesthetic technique was employed; sevoflurane induction, intravenous cannulation, ketamine bolus (2mg/kg) and maintenance (4mg/kg/hr) for 15 minutes. IOP measurements and physiological variables were recorded after sevoflurane induction, then every 2 minutes for a period of 10 minutes, one at 15 minutes as well as 5 minutes after ketamine discontinuation. Results: IOP was measured in 25 patients (50 eyes). Twenty-six eyes (52%) had glaucoma. The mean patient age was 29 months (range 2-88 months). The mean IOP after sevoflurane induction was 3,68mmHg lower than that with ketamine maintenance (sevoflurane eliminated) (95% CI 1,35 to 6,02mmHg) (p=0,002)). Physiological variables return to baseline at 8 minutes, which correlates with the time taken for sevoflurane to be eliminated from exhaled gas. The difference in IOP between ketamine anaesthesia (time 15 minutes) and near wakefulness was only 0,28 mmHg (95% CI -2,23 to 2,79mmHg) (p=0,826). Mixed effects models showed similar trends but a higher baseline (7,85mmHg (6,19 to 9,51mmHg) (p<0,001)) in those with glaucoma when compared to those without. Conclusion: Sevoflurane lowers IOP significantly when compared to ketamine anaesthesia. While eyes with glaucoma had a higher baseline than those which did not have glaucoma, both groups follow similar trends in response to the anaesthetic agents. This standardised anaesthetic protocol allows reliable IOP measurement 15 minutes after termination of sevoflurane and commencement of ketamine infusion, with no reported adverse events.
Open Access
Incidence of intraoperative nausea and vomiting during spinal anaesthesia for caesarean section
(2016) Magni, Bridget; Van Nugteren, Janieke; Dyer, Robert A
The incidence of intraoperative nausea and vomiting during spinal anaesthesia for caesarean section. Background: Nausea and vomiting (IONV) during spinal anaesthesia (SA) for caesarean section (CS) is unpleasant and may interfere with surgery. We studied the incidence of IONV during elective CS, as well as the influence of ethnicity on this outcome. Methods: Two hundred and fifty eight healthy term patients undergoing SA for elective CS were recruited to this prospective observational study conducted at two Cape Town Level 2 hospitals. Standard practice was employed for SA for CS at UCT (University of Cape Town): 2 mL hyperbaric bupivacaine plus 10 μg fentanyl at the L3/4 interspace, and 15 mL/kg cry stalloid co - load. Spinal hypotension was managed with phenylephrine boluses according to a standard protocol. Nausea and/or vomiting were treated by restoration of blood pressure, and metoclopramide. Intraoperative complaints of nausea, and vomiting, were noted. Patients were also interviewed postoperatively as to any experience of intraoperative - or previous history of nausea. Results: Of the 258 patients enrolled in the audit, 112 (43.4%) were non - African and 146 (56.6%) were Black African patients. The overall incidence (95% CI) of nausea was 32% (0.27 - 0.38), with 20% occurring prior to - and 11% after the delivery. The overall incidence of vomiting was 7% (0.05 - 0.11), with 3.2% occurring prior to, and 3.8% after, delivery. The incidence of nausea and/or vomiting was 33% (0.28 - 0.40). Black Africans experienced significantly less nausea than non - African patients (36/145 [24.8%] vs 47/112 [42.0%] respectively, p = 0.004). There was no significant difference in the incidence of vomiting (10/14 5 [6.8%] vs. 8/112 [7.1%] respectively, p = 0.865). The odds of experiencing intraoperative nausea for patients with any blood pressure value <70% of baseline, were 2.46 (95% CI 1.40 - 4.33). Conclusions Though in keeping with international standards, the clinically significant incidence of nausea and/or vomiting of 33% requires adjustments to the management protocol for spinal hypotension. The inclusion of ethnicity as a risk factor for nausea during SA for CS should be considered.
Open Access
The influence of body mass index on sensorimotor block and vasopressor requirement during spinal anaesthesia for elective caesarean section
(2017) Ngaka, Tshebeletso Christian; Dyer, Robert A
Background: It has been suggested that the dose requirement for spinal anesthesia (SA) is lower in obese patients for cesarean delivery. In this prospective, observational, non-inferiority study we tested the hypothesis that obesity would not have a clinically important effect on vasopressor requirements or block height. Methods: Two groups of 25 parturients, Group O (BMI >40 kg/m²) and Group N (BMI <32 kg/m²) requiring elective cesarean delivery were recruited. All patients received 10 mg intrathecal hyperbaric bupivacaine co-administered with 10 μg fentanyl. Dermatomal levels were assessed at 5 and 25 minutes after SA, and at completion of surgery, using light touch and cold sensation in response to ethyl chloride. The primary outcomes were phenylephrine requirement in the first thirty minutes following spinal anesthesia, and maximum block height, measured by the sensation of touch and cold. Secondary outcomes were total phenylephrine dose required, changes in hand grip strength, and peak flow rate. Results: There were no significant between-group differences in median block height as assessed by touch at 5 or 25 minutes, or by temperature at 5 minutes. At 25 minutes, there was a two-dermatome difference in median block height for loss of temperature sensation between Group O and Group N (T2 vs. T4, 95% confidence interval (CI) of the difference in medians 0-2 dermatomes). No blocks extended to cervical dermatomes. The median (range) phenylephrine dose for the first 30 minutes was 150 μg (0-900 μg), and 100 μg (0-1250 μg) in Group N and O respectively. The 95% CI for the difference between the two median doses was -150 μg to 100 μg. There were no differences in median percentage reductions in peak flow rate or median hand grip strength after SA. Mean surgical time was longer in Group O than in Group N (49.1 vs 39.4 minutes, 95% CI difference 1.7 to 17.7 minutes). The mean time for recovery of touch sensation to T10 was longer in Group O (152 vs 132 minutes, 95% CI difference 3.8 to 36.2 minutes). No analgesic supplementation was required. Conclusion: Only a minor increase block height as assessed by temperature occurred in Group O at 25 minutes. Vasopressor requirements during the first 30 min of SA were equivalent. Time for regression of SA block level was longer in the Group O, which may be beneficial considering the longer surgical time. A dose of spinal bupivacaine 10 mg for single-shot SA should not be reduced in morbidly obese parturients.
Open Access
Perioperative comparison of the agreement between a portable fingertip pulse oximeter vs. a conventional bedside pulse oximeter in adult patients (COMFORT trial)
(2018) Smith, Reuben Nathanael; Hofmyer, Ross
Background: Low-cost, portable fingertip pulse oximeters are widely available to health professionals and the public. They are often not tested to ISO standards, or only undergo accuracy studies in healthy volunteers under ideal laboratory conditions. This study aims to pragmatically evaluate the agreement between one such device and a conventional bedside pulse oximeter in a clinical setting, in patients with varied comorbidities and skin pigmentations. Methods: A single-centre equipment comparison study was conducted. Simultaneous measurements were obtained in 220 patients with both a Contec CMS50D Fingertip Pulse Oximeter and a Nihon Kohden Life Scope MU-631 RK conventional bedside monitor. Peripheral oxygen saturations (SpO₂) and pulse rates were documented, and patient skin tone was recorded using the Fitzpatrick scale. Data was assessed using a Bland-Altman analysis with bias, precision and limits of agreement (LOA) calculated with 95% confidence intervals. A priori acceptability for LOA was determined to be 3%, in keeping with international standards. Results: Mean difference (therefore bias) between the conventional and fingertip oximeters for all data was -0,55% (95% CI -0,73 to -0,36%). Upper and lower limits of agreement (95% CI) were 2,16 (1,84 to 2,47) and -3,25 (-3,56 to -2,94) %. Regression analysis demonstrated worsening agreement with decreasing SpO₂. When samples were separated into “normal” (SpO₂ ≥ 93%) and “hypoxaemic” (SpO₂ < 93%) groups, the normal range displayed acceptable agreement between the two oximeters (bias -0,20 with LOA 2,20 to -2,27%), while the hypoxaemic group fell outside the study’s a priori limits. Heart rate measurements had mean difference (LOA) of -0,43 (-5,61 to 4,76) beats per minute. The study was not powered to detect difference among the skin tones, but demonstrated no trend for this parameter to alter the SpO₂ measurements. Conclusions: During normoxia, portable fingertip pulse oximeters are reliable indicators of SpO₂ and pulse rates in patients with various comorbidities in a pragmatic clinical context. However, they display worsening agreement with conventional pulse oximeters during hypoxaemia. Skin tones do not appear to adversely affect measurements.
Open Access
Postoperative outcomes associated with procedural sedation conducted by physician and non-physician anaesthesia providers: findings from the prospective, Observational African Surgical Outcomes Study (ASOS)
(2021) van der Merwe, Freliza; Biccard, Bruce M
Background There is an unmet need for essential surgical services in Africa. Limited anesthesia services are a contributing factor. Non-physician anesthesia providers are utilized to assist with providing anesthesia and procedural sedation in order to make essential surgeries available. There is a paucity of data on outcomes following procedural sedation for surgery in Africa. We investigated the postoperative outcomes following procedural sedation by non-physicians and physicians in Africa. We hypothesized that the level of training of the sedation provider may be associated with the incidence of severe postoperative complications and death. Methods A secondary analysis of a prospective cohort of in-hospital adult surgical patients, representing 25 African countries was performed. An inverse probability of treatment weighting model was developed to assess the association between receiving procedural sedation conducted by a non-physician (vs physician) and in-hospital outcomes. All patients who only received procedural sedation for surgery were included. The primary outcome was the incidence of the composite of severe complications and death. Results 336 patients met the inclusion criteria, of which 98 (29.2%) received sedation from a non-physician provider. The incidence of severe postoperative complications and death was 10/98 (10.2%) in the non-physician group, and 5/238 (2.1%) in the physician group. The association between procedural sedation conducted by a nonphysician provider and in-hospital outcomes showed an eight-fold increase in the odds of severe complications and death (odds ratio 7.7; 95% CI 2.5 to 23.7). Conclusions The modest number of observations in this secondary data analysis, suggests that shifting the task of procedural sedation from physicians to non-physicians in order to increase access to care may be associated with severe postoperative complications and death in Africa. Research focusing on identifying factors contributing to adverse outcomes associated with procedural sedation is necessary to make this practice safer.
Open Access
A record of research directed towards enhancement of the safety of clinical anaesthesia
(1993) Harrison, Gaisford Gerald
Clinical Anaesthesia is an indispensable adjunct to the surgical treatment of disease. It directly affects the lives of a great number of people since every year no fewer than one in every twenty-five persons in the population is required to undergo a procedure which necessitates it. Of itself non-therapeutic, clinical anaesthesia must, above all else. be safe for the patient. Any adverse outcome to clinical anaesthesia and factors relevant to its administration results, at best, in postoperative morbidity for the patient and, at worst, his demise. Identification and examination of the factors and circumstances which have a material influence on the safety of anaesthesia for the patient, provided the motivation for and is the central theme of this collection of research publications which was submitted to the University of Cape Town in fulfilment of the requirements for the award of the Degree of Doctor of Science (Medicine). The publications submitted report the results of forty years of endeavour. In terms of their subject matter, these publications may be broadly grouped into the following five fields of interest: - 1) The Epidemiology of Death Attributable to Anaesthesia. 2) Pharmacogenetic States of concern to the Anaesthetist - a) The Malignant Hyperthermia Myopathy. b) The Acute Porphyrias. 3) The Effects of Anaesthetics on the Liver - Studies of Hepatic Drug Metabolism of relevance to post-Halothane Hepatitis and the hepatotoxicity of anaesthetic agents. b) The treatment of Fulminant Liver Failure. 4) Heat Homeostasis during Anaesthesia - a) Inadvertent Hypothermia during anaesthesia. b) Induced Hypothermia during anaesthesia. 5) Miscellaneous. Within these fields of interest, papers have been grouped in terms of related aspects of the main topic they cover. Editorial comment is included where appropriate. The nature and scope of many of the above investigations was such as to require, for their satisfactory conclusion, collaborative interdisciplinary research combining the endeavours of other clinicians and paramedical scientists. Appropriate recognition of such collaboration has resulted in the multiple authorship registered for many of the publications in this collection.
Open Access
Retrospective observational study of the choice of anaesthesia for caesarean section in patients with eclampsia
(2020) Jordaan, Meandra; Reed, Anthony; Dyer, Robert A
Background Anaesthesia for ceasarean section (CS) in women with eclampsia is a major clinical challenge, and there are limited data concerning the rationale for the choice of technique, and the short-term outcomes. A retrospective audit was performed on practice at a tertiary referral centre in Cape Town. Methods The primary outcome of the audit was the proportion of patients with eclampsia receiving either spinal anaesthesia (SA) or general anaesthesia (GA) for CS, and the assessment of the rationale for the choice of method. A convenience sample of the records of one hundred consecutive patients with eclampsia admitted to the Maternity Centre at Groote Schuur Hospital from 2009- 2013, were studied. Patient demographics, clinical details and outcomes (including relevant results of special investigations), were recorded. The number and percentage of patients receiving GA or SA were documented. The presence or absence of factors influencing selection of the method of anaesthesia, including Glasgow Coma Scale (GCS), degree of urgency of CS, trauma to the oropharynx, number of seizures, control of blood pressure, and the availability of and/or platelet count prior to anaesthesia, were noted. In addition, complications of anaesthesia were described, and short-term maternal and neonatal outcomes were recorded. Results One hundred patient records were screened, and there were 11 exclusions; therefore 89 patient records were analysed. Seven/89 (7.9%) received SA and 82/89 (92.1%) GA. One patient required conversion to GA because of the occurrence of a seizure during attempted SA. All patients receiving spinal anaesthesia were stable and had no postoperative complications. Overall, 63 (70.8%) had a preoperative GCS< 14, and 26 (29.2%) patients had GCS ≥14. Seven patients in the subgroup with GCS ≥14 had SA, and the remaining 19 received GA. GA was performed because there was no platelet count available in 3, pulmonary oedema in 2, difficult airway due to a bitten tongue during a seizure in 2, fetal bradycardia in 2, HELLP syndrome in 1, renal failure in 1, and patient refusal in 1 patient. In 7 women, there was no clear reason why GA was chosen. The median [IQR] Apgar scores at 1 minute were lower in patients receiving GA [(5) (1-9) and 4 (1-9)] in patients with GCS ≥14 and < 14 respectively, versus 8 (6-9) for SA. The number (%) of neonates with Apgar scores ≥ 7 at 1 minute in patients who had SA, was 6 (85.7), compared with 3 (13.6) and 12 (17.9) in patients having GA with GCS ≥14 and < 14 respectively. There were 2 stillbirths and 2 neonatal deaths in the GA group. The median [IQR] length of stay in patients with GCS ≥ 14 was 1 day in the group receiving SA and 2 days in those who had GA; patients with GCS< 14 were ventilated for 3 days. No patients receiving SA required postoperative ventilation, whereas 5/19 (26.3%) patients with GCS ≥14 who received GA required ventilation, for 2 days. Seven patients with GCS< 14 had cerebral oedema, and 2 had cerebral infarcts. There were 2 maternal deaths. Conclusions In this audit, a small percentage of women with eclampsia received SA for CS. A review of the case records suggests that more patients could have safely received SA. A larger prospective audit is required to establish factors influencing safety of spinal anaesthesia for CS in women with eclampsia.