Masters Degrees (Anaesthesiology and Critical Care)

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The ability of the thromboelastogram (TEG® R-time difference between kaolin and heparinase) as a point of care test to predict residual heparin activity after in vitro protamine titration
(Stellenbosch : Stellenbosch University, 2017-12) Joseph, Lauren Ann; Levin, Andrew I.; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Anaesthesiology and Critical Care.
ENGLISH ABSTRACT: Background: Differentiation between surgical bleeding and coagulopathy is critical as re-exploration is associated with increases in mortality and morbidity. Adequate reversal of heparin with protamine at the end of cardiopulmonary bypass (CPB) is critical to prevent postoperative bleeding. Meticulous dosing of protamine is required as excessive dosages has deleterious side effects on clotting. Traditional methods make use of an activated clotting time (ACT) for evaluation of adequate heparin reversal. However, recent use of other point of care (POC) tests, the thromboelastogram (TEG®) has started challenging the utility and exclusive use of ACT to evaluate effective reversal. Differences between thromboelastographic Rkaolin and R-heparinase times is an indicator of residual heparin. However, the exact relationship between these parameters and the exact amount of residual heparin is unknown. The rationale for this study was to accurately determine the relationship between the magnitude of the R-kaolin and R-heparinase time difference and blood heparin concentrations. Aims: This study was performed to define the in-vitro relationship between the difference between the thromboelastographic R-kaolin and R-heparinase time difference (TEG® Delta-kh R-time) and plasma heparin concentrations. The primary outcome was to determined the relationship between the TEG® Delta-kh R-time difference and heparin concentrations. The secondary outcome was to determine the concentration of heparin at or below which R-kaolin times become measureable. Methods: This was a single centre, prospective, randomized laboratory study. Following institutional ethics approval and informed consent, sixty-two samples were taken during CPB from 20 patients meeting inclusion criteria. Samples were randomized to one of three groups which would dictate the protamine dose. The three groups were based on a protamine to heparin ratio (expressed as milligram protamine per milligram heparin administered to the patient) approximating 0.25, 0.5, and 0.75 mg/mg respectively. Each sample of blood was then administered a dose of protamine. The TEG® analysis entailed measuring the R-kaolin and R-heparinase time and noting the difference. Thereafter, each blood sample was sent for heparin concentration determination using an anti-Xa activity assay. Results: No relationship between the measurable R-kaolin time and heparin concentration could be demonstrated (p=0.80), as well as no relationship between measurable TEG® Delta-kh R- time difference and heparin activity (p=0.42). However, we did identify a high probability to be able to predict a measurable R-kaolin time (negative predictive value 90%, 95% CI 74% to 98%) when heparin concentration is less than 1.24IU/ml. Conclusions: We were unable to predict heparin concentration using TEG® in this study. It is likely that this was related to methodological problems. The protamine dose was a complex calculation and there is uncertainty with regard to the actual amounts used. There were also multiple laboratory technicians, with a possible loss of standardization. However, R-kaolin time will likely be measurable at heparin concentrations below 1.24 IU/ml, and not measurable above that value. This observation is immensely valuable for clinicians and researchers. Future studies should take this into account and attempt to determine the relationship between TEG® Delta-kh R- time differences and heparin activity only when heparin concentration are less than 1.24IU/ml.
Airway management of a massive neonatal cervical teratoma : case report and review
(Stellenbosch : Stellenbosch University, 2016-12) Von Steiger, Ilonka; Levin, A. I.; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Anaesthesiology and Critical Care.
ENGLISH ABSTRACT: Congenital cervical teratomas are rare tumours notorious for causing neonatal airway embarrassment. We report the multidisciplinary management of a foetus with an antenatally diagnosed massive cervical teratoma. Initial management with an ex-utero intrapartum treatment (EXIT) procedure failed. The neonate was delivered and airway control was then achieved using a supraglottic airway device. Tracheal intubation was eventually accomplished using fibreoptic bronchoscopy via the supraglottic airway. The discussion addresses perinatal cervical teratoma with the emphasis on airway management and the use of supraglottic airway devices.
Akute postoperatiewe pyn opname in Tygerberg Hospitaal
(Stellenbosch : Stellenbosch University, 2013-12) Murray, Albertus Adriaan; Retief, Francois Wilhelm; Stellenbosch University. Faculty of Medical and Health Sciences. Dept. of Anaesthesiology & Critical Care.
AFRIKAANSE OPSOMMING: Doelwit: Om die voorkoms en erns van postoperatiewe pyn te bepaal gedurende die eerste 24 uur periode in 'n tersiëre hospitaal met beperkte hulpbronne. Om spesifieke groepe en risiko faktore wat verband hou met 'n hoër voorkoms van pyn te identifiseer. Ontwerp: Opname met behulp van 'n vraelys. Opset: Ontwikkelende land tersiëre staatshospitaal met alle chirurgiese dissiplines. Populasie: Pasiënte van alle chirurgiese dissilpines bo 12 jaar oud en toegelaat vir 'n minimum van 24 uur postoperatief. Metodiek: Opname 24 uur na die operasie met behulp van 'n vraelys met 3 visuele analoog pyn skale (VAS) en 'n vraag. Verdere data is ingesamel vanaf die narkose en voorskrif kaarte. Resultate: Postoperatiewe pyn is gerapporteer as matig in 25% en erg in 37% van pasiënte. Onafhanklike risikofaktore vir matige of erge postoperatiewe pyn was ‘n jonger ouderdom, vroulike geslag, nood en abdominale chirurgie. Prosedures met die hoogste voorkoms van matige of erge pyn was keisersnitte (87%) en ortopediese chirurgie van die onderste ledemate (80% - 85%). Morfien toediening was baie minder gereeld as voorgeskryf. Gevolgtrekking: Voorkoms van postoperatiewe pyn in hierdie hulpbron beperkte omgewing is hoog, maar vergelyk met ander instansies. Spesiale sorg moet geneem word in die geïdentifiseerde groepe wat verband hou met 'n hoër voorkoms van pyn. Roetine sistemiese analgesie moet meer tydig toegedien word, veral wanneer die effek van regionale narkose termineer.
An audit of the time spent by patients in the post anesthetic care unit before and after the introduction of a discharge criteria scoring system at Tygerberg Academic Hospital
(Stellenbosch : Stellenbosch University, 2014-04) Dwyer, Sean; De Kock, M.; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Anaesthesiology and Critical Care.
ENGLISH ABSTRACT: BACKGROUND Post anesthesia discharge criteria scoring systems have been used successfully to aid discharge from the post anesthetic care unit (PACU) for over 40 years. They do not replace, but rather act in conjunction with good clinical judgment, and provide concise, standardized documentation of a patient’s readiness for discharge. 1,2,3,4,5 In order to improve patient safety, provide clear documentation and to aid future audit, a discharge criteria scoring system was developed for use in our PACU (Addendum A). It is a modification of the Aldrete Scoring System and the modified Post Anesthetic Discharge Scoring System (PADSS) proposed by Chung.1 There is a steadily increasing patient burden on the existing medical infrastructure in South Africa. Tygerberg Academic Hospital is no exception, and because of the high demand on our theatre services, optimal efficiency is essential. We speculated that our discharge criteria scoring system might increase the efficiency of our PACU when compared to the traditional time based system. The more healthy patients, undergoing minor procedures, could potentially spend less time in PACU, allowing the nurses to focus on problem cases. Increasing the speed of transit might also help prevent delays in theatre due to lack of bed space in PACU. Our primary endpoint was to compare the duration of time spent by patients in the PACU at Tygerberg Academic Hospital, from the moment they are admitted, to the time they are discharged to the ward, before and after the introduction of a discharge criteria scoring system. While planning the audit, one of the factors that staff identified as contributing to delayed discharge from PACU, was the time it took for the wards to collect their patients. A secondary objective, therefore, was to assess the amount of time that elapsed between calling the ward to collect the patient, and the patient leaving PACU. METHODS AND MATERIALS Prior to commencing the audit, approval was obtained from the Human Research Ethics Committee of the Faculty of Health Sciences of the University of Stellenbosch and Tygerberg Academic Hospital. The Audit, its purpose and possible benefits, was discussed with representatives of the nurses working in PACU, and written consent was obtained from those who would be involved in the data collection (Addendum B). Audit forms (Addendum C), collection boxes, and posters reminding staff to participate in the audit were prepared. Our first audit was performed over approximately a week in August 2012. During this period, the traditional time-based discharge system was still in operation. Data was captured from 327 patients. Audit forms were placed in a collection box, which was cleared daily by the primary investigator. The discharge criteria scoring system was introduced to the PACU staff in January 2013. The nurses were trained in its use, and a one month period was allowed for all involved to become accustomed to the new system. A second audit was performed in February 2013, again over a week, during which we gathered data from 313 patients. RESULTS The median value of the time spent by patients in the PACU decreased from 1 hour 25 minutes, to 1 hour 15 minutes, after introduction of the discharge criteria scoring system. This was statistically significant (p-value = 0.003). The median time between calling the ward to collect a patient, and the patient leaving recovery, was 15 minutes. CONCLUSION The main finding of the study was that the introduction of a discharge criteria scoring system decreased the median duration of time spent by patients in the post anesthetic care unit at Tygerberg Academic Hospital.
Blood pressure measurement in the obese patient: a comparison between non-invasive proximal forearm and radial arterial blood pressure measurement
(Stellenbosch : Stellenbosch University, 2017-12) Verkhovsky, Anna; Smit, Marli; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Anesthesiology and Critical Care.
ENGLISH ABSTRACT: ABSTRACT Background: South Africa has a high prevalence of obese adults. When these (obese) individuals present to a health care facility, blood pressure measurement will play an important role during routine medical evaluation. Accurate non-invasive blood pressure monitoring is a challenge in obese individuals secondary to inaccurate readings associated with inappropriate cuff size, structural differences of the upper arm as well as short upper arm length. Our aim was to identify an accurate, affordable, minimally invasive and low-risk blood pressure measurement modality in obese patients. Methods: This study included 30 patients with a body mass index of greater or equal to 30 kg/m2 presenting for surgery or staying in a High Care Unit at Tygerberg Hospital. In all of these patients, an intra-arterial line was included as part of their routine care. We compared the non-invasive (mean, systolic and diastolic) blood pressures readings from the proximal forearm, with the gold standard, being intra-arterial blood pressure readings. Results: There was poor agreement between the mean intra-arterial blood pressure measurement and the noninvasive blood pressure (NIBP) measured at the forearm. The mean NIBP measured at the forearm overestimated the intra-arterial blood pressure reading by 2% (±8.1 %. P 0.031). The computed upper and lower levels of agreement between the 2 methods ranged from -19.3 to 15.2%. Systolic NIBP measurements at the forearm over-estimated the IABP measurements by 0.9% (P 0.295). Upper and lower levels of agreement between the 2 methods ranged from -16.4 to 14.7%. Larger discrepancies between the two methods were observed for diastolic blood pressure measurements with a mean difference of -5.8% (P <0.0001). Conclusion: We cannot recommend that the forearm NIBP reading be used as an accurate, non-invasive and cost effective substitute to measure blood pressure in obese patients.
Central oxygen pipeline failure
(Stellenbosch : Stellenbosch University, 2014-04) Mostert, Lelane; Coetzee, Andre; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Anaesthesiology and Critical Care.
ENGLISH ABSTRACT: Case Report - A case is described of central oxygen pipeline failure that occurred at a large academic hospital and its subsequent implications for managing the situation. Literature review - The literature review undertaken focused on the current state of affairs with regards to anaesthetic staff's knowledge of and preparedness for the management implications of central oxygen pipeline failure. The events I describe below demonstrate a significant deficiency in the staff’s understanding of and training for the crisis, which should be remedied to improve patient safety. Specific measures are suggested in the literature to prevent such incidents and guidelines are available to manage central oxygen pipeline failure. These are reviewed in this study. Recommendations - This study attempts to bring together the most critical aspects that need to be addressed to safely manage similar future incidents. Prevention should include measures to implement clearly stated disaster management plans and increased awareness with regards to the medical gas pipeline system (MGPS), simulation training, efficient alarm systems, personally conducted routine evaluations of equipment and emergency backup systems by anaesthesiologists and effective communication between hospital staff. Careful planning and successful coordination during maintenance and modification of the medical gas pipeline system, using piston-type or air-driven, rather than oxygen-driven, ventilators and optimal design of the hospital bulk oxygen system can contribute to reduce risks. In the event of central oxygen pipeline failure a specific sequence of actions should be taken by the anaesthesiologist and a clear institutional operational policy is described.
Comparison of haemoglobin values measured at point of care with the standard laboratory value
(Stellenbosch : Stellenbosch University, 2016-12) Johnson, Marianne; Marwick, Peter; Stellenbosch University. Faculty of Health Sciences. Dept. of Anaesthesiology and Critical Care.
ENGLISH ABSTRACT: Point of care (POC) haemoglobin (Hb) concentration estimations guide acute decisions on red blood cell transfusion. We studied the accuracy of three POC devices when compared to central laboratory Hb testing and how between-method Hb disagreements could affect the decision to transfuse. The Health Research Ethics Committee of the University of Stellenbosch approved a method comparison study of perioperative Hb concentration measurement in arterial blood sampled from 58 adult cardiothoracic surgery patients. The Hb concentration was measured by using two Ilex GEM PremierTM 3500 blood gas analysers (Blood gas A and Blood gas B), a HemoCue® Hb 201+ System (HemoCue), and our central laboratory’s Siemens Advia® 2120 flow cytometry system (Laboratory haemoglobin). We regarded that a between-method Hb difference exceeding 10% (1 g/dL at an Hb value of 10 g/dL), would likely erroneously influence the transfusion decision. Furthermore, one unit of packed red blood cells will increase the Hb by ±1 g/dL and clinically represents the smallest transfusion associated risk that a patient will be exposed to. From the 58 patients included in the study, 70 central laboratory Hb concentration (Laboratory haemoglobin) measurements and 58, 72, and 71 measurements by the HemoCue, blood gas analyser A (Blood gas A) and blood gas analyser B (Blood gas B), respectively were taken. We found that the mean POC (HemoCue, Blood gas A, and Blood gas B) Hb levels underestimated the mean central laboratory Hb level by 0.79 g/dL, 0.81 g/dL, and 0.67 g/dL, respectively. The 95% confidence interval (CI) of the between-method difference revealed that unlike the Blood gas A (0.43 to 1.15 g/dL) and Blood gas B (0.46 to 1.16 g/dL) values, the HemoCue (0.47 to 0.87 g/dL) values did not breach the predetermined 1 g/dL limit. A Bland-Altman analysis revealed similar between-method mean Hb differences. However, the HemoCue upper and lower limits of agreement (LOA) were narrower, and the 95% CI of the LOAs do not overlap with those of Blood gas A and Blood gas B. Overall the HemoCue is more accurate. Also, the 95% CI of the HemoCue’s lower LOA was below 1 g/dL. This device does not give readings that clinically overestimate the Laboratory haemoglobin. Similarly, the mountain plot demonstrates the greater agreement and precision of the HemoCue device, as compared to Blood gas A and Blood gas B. An error grid analysis focused on the Hb 6 to 10 g/dL clinical decision-making range where only a 10% error was permitted. The error grid analysis revealed that the HemoCue and blood gas analysers had potential transfusion errors of less than 5% and more than 20%, respectively. However, none of the evaluated devices produced values in the major therapeutic error zone, where a decision to transfuse or not transfuse blood will be made erroneously.
Comparison of minimally and more invasive methods of determining mixed venous oxygenation
(Stellenbosch : Stellenbosch University, 2013-12) Smit, Marli; Levin, Andrew I.; Coetzee, J. F.; Stellenbosch University. Faculty of Medicine & Health Sciences. Dept. of Anesthesia and Critical Care.
ENGLISH ABSTRACT: Circulatory efficiency is the relationship between oxygen consumption and global oxygen delivery. Manipulation of circulatory efficiency has been shown to be beneficial in critically ill surgical and medical adults, and in children. Circulatory efficiency is best assessed by measuring an index of mixed venous oxygenation (content, saturation and partial pressure) and viewing this in the context of oxygen consumption. Mixed venous oxygenation has until now required intermittent sampling via a pulmonary artery catheter, or by using a pulmonary artery catheter equipped with a fibre optic bundle for continuous mixed venous oxygen saturation monitoring. However, the use of the pulmonary artery catheter is declining as it has been (correctly or incorrectly) indicted of being an “invasive” tool. Attempts have been made to estimate mixed venous oxygenation non-invasively using the “NICO” monitor[6], near infrared spectroscopy[7], skeletal muscle oxygen saturation[8], thenar muscle oxygen saturation[9] and transtracheal pulse oximetry.[4]While all of them effectively trended mixed venous oxygen saturation, their accuracy and use as a resuscitation endpoint are in doubt. Sampling central venous as a surrogate of mixed venous oxygenation is fraught with problems, particularly in sicker patients. Significant differences in oxygenation can be demonstrated between the pulmonary arterial and central venous sampling sites in shock states,[3, 10] in acutely ill post-surgical patients [11] and under varying hemodynamic conditions.[12] With the decline in the use of the pulmonary artery catheter, minimally invasive cardiac output determination is becoming increasingly popular. Apart from that their accuracy (particularly un-calibrated devices) has been questioned; they also cannot determine mixed venous oxygen saturation. To obtain a more reliable and refined, but less invasive, estimate of mixed venous oxygenation would be beneficial. The primary aim of this study was therefore to investigate whether venous oxygenation (mixed venous oxygen content, saturation and partial pressure) could be accurately predicted by minimally invasive methods of determining cardiac output and non-invasive calorimetric methods of measuring oxygen consumption. The methods compared were the current invasive gold standard represented by direct sampling of mixed venous blood and thermodilution cardiac output using a pulmonary artery catheter, with a less invasive method of calculating mixed venous saturation, the latter comprised of 4 elements: 1. Cardiac output was measured using a minimally invasive technique, namely lithium dilution (LiDCo®). 2. Oxygen consumption was measured with a non-invasive calorimetric device (M-COVX™ module manufactured by General Electric Corporation). 3. Arterial oxygen content was estimated using blood sampled via an arterial catheter. 4. These 3 variables were inputted into Fick’s equation and solved for venous oxygen content (CvO2 = CaO2 –VO2/CO). Thereafter, using the calculated venous oxygen content as well as the haemoglobin concentration, mixed venous oxygen saturation and partial pressure was estimated using an Excel® spreadsheet (Appendix G) relating oxygen saturation and partial pressure using standard oxygen dissociation curve formula, and calculating oxygen content from various haemoglobin concentrations. Analysis of the data was performed predominantly using Bland Altman analysis. LiDCo® derived cardiac output overestimated that measured using intermittent thermodilution PAC by a clinically significant average of 0.82liters/minute or 26%. The pulmonary artery catheter derived oxygen consumption underestimated that measured by the metabolic module by 52 ml/minute or 27%. Oxygen consumption was the parameter having the largest percentage error (27%) and difference between the Bland Altman upper and lower limits of agreement. The difference between oxygen consumption measured by indirect calorimetry is expected to exceed that calculated using the indirect Fick method by 20 to 30% because intra-pulmonary oxygen consumption is excluded when using this method.[ 13] However, the scatter exhibited by the calorimetry estimations of oxygen consumption was probably the major reason for the discrepancy between the calculated and measured mixed venous oxygenation variables. Despite small (12.0 to 26.3 %) differences between measurements in individual patients, venous oxygenation variables measured by the invasive and less invasive techniques were statistically different. We also considered the magnitude of these differences to be clinically significant as we were of the opinion that relying on the calculated results could adversely impact clinical decision-making. In conclusion, we could not estimate venous oxygenation accurately enough using minimally invasive methods of determining cardiac output and non-invasive methods of measuring oxygen consumption to be clinically useful.
A comparison of the potentiation by desflurane of the effects of rocoronium and cisatracurium
(Stellenbosch : Stellenbosch University, 2013-12) Scheepers, Pamela Anne; Coetzee, Johan Francois; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Anaesthesiology and Critical Care.
ENGLISH ABSTRACT: Introduction: Of the volatile anaesthetic agents, desflurane causes the greatest degree of potentiation of the neuromuscular blocking drugs (NMB). The purpose of this study was to determine whether desflurane prolongs the effects of 3xED95 doses of rocuronium and cisatracurium to the same degree. The two NMB represent potent and less potent classes respectively. Methods: Informed, written consent was obtained from 63 adult patients scheduled for routine surgery. They were randomly allocated to one of four groups to receive either desflurane-sufentanil (end-tidal partial pressure 4.0 kPa) or propofol-sufentanil anaesthesia and either rocuronium (0.9mg/kg) or cisatracurium (0.15mg/kg). All patients received a target-controlled sufentanil infusion (0.5 ng/ml). Neuromuscular blockade was recorded using accelerometry (TOFGUARD ®, Organon) while patients recovered spontaneously to a Train-of-Four ratio of 0.9 (TOFR0.9). Data were analysed using one- and two-way analysis of variance. The main effects were the types of anaesthetic and NMB on indices of recovery. Results: Compared with propofol-sufentanil anaesthesia, mean times to recovery to T125% and TOFR0.9, were prolonged by desflurane-sufentanil (p<0.01). There were no interactions. Mean prolongation of time to TOFR0.9 was 41 min (SD 36) for cisatracurium and 26.6 min (SD 39) for rocuronium. Discussion: Whereas previous studies did not reveal prolongation of the duration of action of rocuronium by desflurane, we demonstrated a statistically significant prolongation of the spontaneous recovery times of both rocuronium and cisatracurium by desflurane. From the data we could not conclude that there was a difference between the two NMB. A power study revealed that in order to detect a difference between times to recovery to TOF0.9, a sample size of 101 subjects per group would be required. Conclusion: Desflurane prolongs the mean time to spontaneous recovery from neuromuscular blockade after 3xED95 doses of both cisatracurium (a potent NMB) and rocuronium (a less potent NMB). There was wide inter-individual variation in times to spontaneous recovery. Any difference in the mean prolongations between the different types of NMB is unlikely to be of clinical importance.
Effect of a carbohydrate lollipop on the gastric volume of fasted pediatric patients
(Stellenbosch : Stellenbosch University, 2022-05) Odendaal, Pieter Schalk; Burke, Annemie; Coetzee, Johan; Burke, Annemie
ENGLISH ABSTRACT: Background: Preoperative fasting is part of routine practice. Children subjected to prolonged preoperative fasting often suffer adverse effects. Consuming a preoperative lollipop may lessen their anxiety and have clinical benefits. Aims: To assess the effect of consuming a lollipop on gastric volume and the feasibility of administering a lollipop to a child preoperatively. Methods: In this prospective, repeated measures interventional study, we measured gastric antrum volume using ultrasound in children aged 2-18 years. We measured antrum volumes after participants had fasted for a minimum of six hours for solids and two hours for clear fluids. They then consumed a standard carbohydrate lollipop, and we repeated the antrum volume measurements after one hour. Results: Of the 38 patients enrolled, 32 completed the study; four had ingested additional food or liquid, and two were diagnosed with systemic disease the day after data collection. The gastric volume data were normally distributed. The mean volume change was 0.01 ml.kg-1 (95% CI -0.02 to 0.05; p = 0.460). The mean post-lollipop volume was 0.51 ml/kg (95% CI 0.43 to 0.58). Conclusions: Consuming a standard lollipop did not affect the gastric volume of fasted pediatric patients.
The effect of high dose morphine compared to fentanyl infusion on serum levels of mast cell tryptase during cardiac surgery
(Stellenbosch : Stellenbosch University, 2016-12) Barbieri, Mia; Levin, Andrew I.; Stellenbosch University. Faculty of Health Sciences. Dept. of Anaesthesiology and Critical Care.
Background: Morphine directly activates cutaneous mast cells in a seemingly dose-dependent manner, resulting in the release of both histamine and tryptase into the bloodstream. Tryptase is almost exclusively stored in mast cells. Elevated serum tryptase concentrations serve as an indicator of mast cell activation and have become the most frequently used laboratory investigation in anaphylaxis. Following a clinical diagnostic dilemma our study was aimed at answering whether mast cell tryptase concentration remains useful in supporting the diagnosis of anaphylaxis even after administration of high dose morphine. Methods:We conducted a non-blinded, randomized controlled trial comparing the effects of fentanyl and high dose morphine, on serum mast cell tryptase concentrations. A power analysis was performed. Twenty adults undergoing cardiac surgery were randomly assigned to one of two opioid regimens. Both groups received a fentanyl bolus of 3 to 8 mcg/kg at induction. In the fentanyl group this was followed by a fentanyl infusion of 5 to 10 mcg/kg/hr until completion of surgery. Patients in the morphine group received morphine 1 mg/kg infused over thirty minutes. Baseline serum mast cell tryptase concentrations were determined directly prior to induction of anaesthesia and again 90 minutes after the start of the opioid infusion. The primary endpoint was statistical differences in tryptase concentrations between the morphine and fentanyl groups at the two time periods. Results: Ten patients of similar demographics were enrolled in each group. In the fentanyl group the second, 90-minute mast cell tryptase concentration was statistically significantly (10.1%) lower (p = 0.006) than baseline. Despite the 95% confidence interval of the difference between the means (-1.06 to -0.34 mcg/L) not including zero , this was not a clinically important difference. In the morphine group serum mast cell tryptase concentrations in the second (90 minute) sample were not statistically different from baseline values, the 95% confidence interval including zero. No between-group differences in tryptase concentration were detected. One patient in the morphine group exhibited a clinically significant 50,4% increase in tryptase concentrations, albeit from a high baseline of 11.9 mcg/L, which in this small study constitutes a prevalence of 10% (95% CI 1.8% to 40.4.) Conclusion: In this small pilot study, serum mast cell tryptase concentrations were unaffected by whether fentanyl or high dose morphine was administered. The null hypothesis, that there is no significant increase in serum mast cell concentrations after high dose morphine compared to fentanyl during cardiac anaesthesia and surgery, was therefore accepted. Larger studies are however needed to ensure a robust result, especially in the morphine group
The effect of supraclavicular brachial plexus blockade on Bispectral index (BIS): a pilot study
(Stellenbosch : Stellenbosch University, 2016-12) Naidoo, Rubendren; Firfiray, Latifa; Stellenbosch University. Faculty of Health Sciences. Dept. of Anaesthesiology and Critical Care.
Background: Many studies have demonstrated that neuraxial (spinal and epidural) anesthesia decreases level of consciousness.1-3 Plausible causal theories relate to afferent spinothalamic tracts suppression, rostral neuraxial spread of local anaesthetics, and systemic local anaesthetic effects.1-3 No study has thus far interrogated the effect of non-neuraxial loco-regional anesthesia on level of consciousness. Methods: Un-premedicated ASA 1 patients undergoing elective hand surgery (n=20) were administered ultrasound-guided supraclavicular brachial plexus blocks using 2mg/kg of 0.5% bupivacaine. A pre-block numeric pain visual analogue score was performed. No sedation was administered. Bispectral index (BIS) control readings were obtained before brachial block. For an hour after the block, the lowest BIS readings, within each subsequent 10minute interval was documented. Over the 60minute observation period, a decrease in BIS reading was considered as being any change of BIS≤80. Results: In the hour post-block, BIS values ≤80 occurred in 65% (CI95% 40.4 to 83.6%) of patients when compared to their pre-block (control) BIS values. This result did not correlate to age, gender or the nature of the illness requiring surgery (traumatic versus pre-existing, chronic illness). There was no difference in the mean pre-block pain scores between the patients who experienced a drop in BIS≤80 and BIS>80 with mean values of 2.45 (IQR; CI95) and 2.44 (IQR; CI95) respectively (two-sample Wilcoxon rank-sum test, p = 0.9022). Conclusion: Brachial plexus blockade itself, in the absence of sedative drugs, reduced BIS. This is consistent with light to moderate sedation.
Die effek van lignokaien op segmentele miokardiale funksie in die oop borskas isgemiese varkhart onder algemene narkose
(Stellenbosch : Stellenbosch University, 1991-12) Moolman, Johannes, Albertus; Coetzee, Andre; Stellenbosch University. Faculty of Medicine and Health Sciences. Department of Anaesthesiology and Critical Care.
AFRIKAANSE OPSOMMING: Die effek van lae (1 mg/kg) en hoe (4mg/kg) bolusse intraveneuse lignokaYen op regionale funksie is ondersoek in 13 varkharte. Deur middel van 'n betekenisvolle vernouing van die linker afdalende koronere (LAD) arterie is 'n isgemiese segment in die LAD voorsienings gebied veroorsaak. Miokardiale funksie is bepaal in die isgemiese LAD-gebied en die normals voorsienings gebied van die sirkumfleks (Lx) koronere arterie. Konstriksie van die LAD het miokardiale isgemie in die LAD-segment veroorsaak sender om sistoliese disfunksie te induseer. lsgemie ge'lnduseerde diastoliese disfunksie blyk uit die toename in helling van styging in linker ventrikel druktoename · (df) (p<0.05), persentasie toename in postsistoliese verkorting (PSS) (p<0.02), afname in effektiewe verkortingsarea van die LAD-segment (p<0.05), afname in Pv02 van die dreinerende vene van die LAD-gebied (p<0.05) en toename in korone,re veneuse laktaat vanaf die isgemiese gebied. Die graad van isgemie wat veroorsaak is het nie sistoliese segmentele kontraktiele funksie be'lnvloed nie - geen verandering in die persentasie verkorting van die LAD-segment se spiervesels is aangetoon nie. Lignoka'!'en het geen beduidende invloed op miokardiale funksie gehad nie, hetsy globaal of regionaal. Die geringe afname in hartspoed en slagvolume het nie 'n betekenisvolle vermindering in die kardiale omset veroorsaak nie en geen betekenisvolle styging in eind-diastoliese druk het plaasgevind nie. Beide bg. bevindings is in teenstelling met bevindings van ander outeurs (Gee 1990, Klein 1968, Nath 1986). Regionale funksie het nie hipokinese by die terapeutiese plasma . konsentrasies van die middels soos bereik in die eksperiment getoon nie - Ees het nie paradoksaal toe geneem , en D0, die snypunt van Ees met die lengte-as, het nie na regs geskuif nie. Diastoliese funksie van beide die isgemiese en normals miokardiale segments het geen disfunksie getoon na lignokaYen toediening nie. Die maksimale vesellengte by eind-diastolie, helling van diastoliese vulling en post-sistoliese verkorting het nie verander nie. Die invloed van lignoka'ien op die koronere vloei kan slegs by afleiding evalueer word, aangesien koronere vloei nie direk bepaal is nie. Die area onder die druk-lengte kurwe, wat 'n indirekte parameter van segmentele werk is, het nie verander met toenemende dosisse lignokai'en nie. Dit dui op 'n onveranderde miokardiale suurstof verbruik van die LAD- en Lx-segment. Die effektiewe verkortingsarea, wat meer sensitief as die totale area onder die • druk-lengte kurwe is vir veranderinge in koronere bloedvloei (Safwat 1991), het eweneens onveranderd gebly wat die feit ondersteun dat lignoka'ien nie die miokardiale suurstof verbruik verminder het nie. Laktaat metabolisme as indirekte parameter van miokardiale isgemie het geen betekenisvolle veranderinge na die toediening van lignoka'ien getoon nie, soos ook weerspieel word deur die afwesigheid van 'n korrelasie tu~sen koronere veneuse laktaat en serumvlakke van lignoka'ien (korrelasie koeffisient = -0.32). Die kliniese ekwivalent van die situasie wat hier ondersoek is, is die. pasient . met 'n betekenisvolle koronere stenose en meegaande miokardiale isgemie wat 'n disritmie ontwikkel wat behandel moet word. Die belang van hierdie studie is dat bewys is dat lignokaren geen betekenisvolle effek op isgemiese miokardium gehad het by terapeutiese serumvlakke lignokai'en nie. Die bekende hoe terapeutiese indeks van die middel in nie-isgemiese miokardium word weereens bevestig. Die resultate van hierdie studie sal in gedagte gehou moet word by die gebruik van nuwe anti-aritmiese middels, en die klinikus sal moet kan verantwoord of die nuwe middels hierdie bekende ou middel in veiligheid, effektiwiteit en koste-effektiwiteit oortref.
Intra-articular bupivacaine : a literature review including a pilot study investigating the safety of intra-articular bupivacaine to chondrocytes
(2015-12) Van der Merwe, Willem Jacobus; Firfiray, L.; Coetzee, Andre; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Anesthesiology and Critical Care.
ENGLISH ABSTRACT: Background: Today, intra-articular bupivacaine injections are common practice, with very good analgesic effects. This method of analgesia is utilized by general practitioners, orthopedic surgeons and anesthesiologists. Unfortunately, since 2004, more than 200 cases of chondrolysis were noted following intra-articular bupivacaine infusion. Numerous studies have investigated the safety of intra-articular bupivacaine. The aim of this thesis was to quantify the risk of chondrolysis with intra-articular bupivacaine and to guide medical practitioners in safe practice. Methods: A literature review was done of the most recently published original research, meta-analysis and review articles. Adverse outcomes were mostly associated with bupivacaine infusions, rather than with single intra-articular doses of bupivacaine. Limited data on the safety of a single dose of intra-articular bupivacaine was found. We conducted a pilot study to investigate the safety of a single dose of intra-articular bupivacaine. A paired, case-controlled, experiment was done using four merino sheep. The nul hypothesis was that a single dose of intra-articular bupivacaine did not cause chondrolysis when compared with a dose of intra-articular normal saline. Our results were added to the thesis to further quantify the risk. Results: Numerous in vitro and in vivo studies confirmed that bupivacaine is chondrotoxic. The chondrotoxic effect is time, dose and concentration dependent. Our pilot study revealed that single dose intra-articular bupivacaine may also be unsafe for chondrocytes. Conclusion: The administration of intra-articular bupivacaine is toxic to chondrocytes. The chondrotoxic effect of intra-articular bupivacaine is time, dose and concentration dependent. Infusions of intra-articular bupivacaine should be contra-indicated. From the limited data available on single dose intra-articular bupivacaine, it appears that it is also chondrotoxic. Magnesium, morphine and clonidine may be safer for intra-articular use, but this needs further investigation.
An investigation into the use of condoms as ultrasound probe covers during sterile procedures
(Stellenbosch : Stellenbosch University, 2015-03) Sooraj, Nayandra Runveer; Retief, Francois Wilhelm; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Anaesthesiology and Critical Care.
Purpose The purpose of this study was to investigate the use of condoms as an alternative to commercially available ultrasound probe covers for the maintenance of sterility during ultrasound-guided medical procedures. We hypothesised that condoms are sterile in their packaging and are effective barriers to bacterial translocation during sterile procedures. Methods Phase 1 examined whether condoms are sterile in their packaging. Ten condoms were removed from their packaging under sterile conditions and placed into nutrient broth. After 24 hours of incubation, they were checked for turbidity as a measure of contamination. The second phase of the study examined the ability of condoms to prevent translocation of bacteria from heavily contaminated probe head models to growth media. The experimental model was designed to simulate clinical conditions. Rectangular glass coplin jars were dipped into KY jelly inoculated with Klebsiella and Staphylococcus. Condoms were subsequently placed over the ends of the jars. After a brief exposure period, the condoms were removed carefully and the uncontaminated tips dipped individually into different 20ml containers of nutrient broth. The containers were then incubated for 24 hours, after which they were examined for turbidity as an indicator of bacterial translocation. The experiment was conducted using sterile precautions akin to procedures performed in operating theatres. Results In the first phase, one of the ten condoms (10%; 95% confidence intervals 0.3% - 45%) showed bacterial growth. In the second phase, 18 of the 30 samples (60%; 95% confidence intervals 41% - 77%) showed bacterial growth. Conclusion The results of the study suggest that the use of condoms, as sterile ultrasound barriers, may not prevent translocation of bacteria in clinical practice. A number of factors may influence the effectiveness of condoms, such as the probe head size, bacterial load and manufacturing quality of the condom. Further studies are needed to compare condoms to commercially available probe covers.
Lactate concentration and oxygen flux post cardiopulmonary bypass: a pilot study
(2020-06) Schoeman, Doreen; Smit, Marli; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Anesthesiology and Critical Care.
ENGLISH ABSTRACT: Objective: To identify the incidence and the main contributing factor of postoperative hyperlactataemia following cardiopulmonary bypass surgery. Design: Single-centre, prospective, non-randomized, observational pilot study. Setting: Tertiary hospital, University setting. Participants: Twenty-six patients who all underwent cardiopulmonary bypass for elective cardiac surgery and who met the inclusion criteria. We excluded patients with pre-existing conditions or medications that could possibly alter lactate metabolism or contribute to aerobic increase in lactate production. Interventions: Observational. Measurements: Arterial lactate, mixed venous oxygen saturations (SvO2), haemoglobin, arterial saturation, and mixed venous partial pressure (PvO2) were measured. Delivery of oxygen (DO2) and oxygen consumption (V𝑂𝑂̇2) were calculated for the first twelve postoperative hours. Factors potentially influencing V𝑂𝑂̇ 2 (temperature, shivering, pain, anxiety, the use of inotropic support, and the presence or absence of ventilation) were also documented. Main results: Transient hyperlactataemia (that peaked between postoperative hours two to eight) occurred in 47% of cases following cardiopulmonary bypass. Postoperative hyperlactataemia occurred as a result of an increase in oxygen consumption (V𝑂𝑂̇ 2). The use of adrenaline and an increase in temperature (as a result of passive rewarming) were identified as the contributing factors responsible for this V 𝑂𝑂̇ 2 increase. Postoperative delivery of oxygen (DO2) remained adequate; as illustrated by normal to high cardiac output, haematocrit, and arterial saturations.
Postoperative pain assessment : a review of nursing practices at Tygerberg Academic Hospital
(Stellenbosch : Stellenbosch University, 2018) Dippenaar, Petrus Johannes; Naidoo, R.; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Anaesthesiology and Critical Care.
ENGLISH ABSTRACT: Pain is a complex, subjective, physical and emotional experience with large individual variation. Murray et al has estimated a prevalence of 62% of severe postoperative pain in Tygerberg Academic Hospital Surgical Wards (TAHSW). Efficient pain management stems from accurate pain assessment. Cultural influences and level of education determines patients’ willingness and ability to disclose the pain experience, as well as the health care provider’s ability to accurately assess it. Nurses with a greater level of training and experience tend to acknowledge self-report of pain to establish the existence of pain, but use objective parameters to determine intensity. Pain rating scales should be used to grade intensity of pain, as this is the easiest dimension to delineate. Acute pain has recently been regarded as the “fifth vital sign”, and routine assessment has created greater awareness of pain. Unfortunately, the lack of proper management protocols, has resulted in an increase in the inappropriate administration of opioid analgesics with an increased incidence of postoperative respiratory depression. Level of sedation secondary to opioid administration correlates with the risk of apnoea. Respiratory depression mostly occurs at night during the first 24 hours, due to lack of proper monitoring. Nurses need to be trained to recognise the danger signs of opioid induced respiratory depression.
The Prevalence of Propofol Contamination in the Tygerberg Theatre Complex
(Stellenbosch : Stellenbosch University, 2020-12) Drude, Carmen; Johnson, Marianne; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Anaesthesiology and Critical Care.
ENGLISH ABSTRACT: Propofol is a widely used intravenous anaesthetic agent. Soon after its introduction into the market, propofol-related postoperative infections were reported. It was determined that the emulsion supports growth and manufacturers provided strict aseptic guidelines with regards to propofol usage, but it has been shown that clinicians in South Africa do not adhere to these guidelines. The primary objective of our observational study was to determine the prevalence of contamination of syringes containing propofol (Fresenius’ Propoven® 1%, Fresenius Kabi, Sweden) in the Tygerberg Hospital Theatre Complex. Samples of syringes containing propofol were collected from various randomised operating theatres over a period of 15 days and specimens cultured and tested for growth of organisms. The secondary objective was to differentiate between contamination occurring in e mergency and elective surgery operating theatres and investigate the difference in propofol contamination when used by junior versus more senior anaesthetists. We demonstrated an unacceptably high propofol contamination prevalence of 41.8% (95% CI: 32.5%, 51.6%). Coagulase negative staphylococcus (CONS) was the most prevalent organism. Overall, 58.18% of samples demonstrated no growth after 2 days. Regarding our secondary objective, there was no statistically significant difference regarding the prevalence of propofol contamination of samples taken from the emergency and elective operating theatres (p = 0.95; risk ratio 1.02; 95% CI: 0.55; 1.89). Propofol syringes handled by senior versus junior anaesthetists revealed a similar result (p = 0.65; risk ratio 0.90; 95% CI: 0.58; 1.41). CONS are often contaminants and the bulk of organisms we cultured are non-pathogenic in healthyhosts but can be lethal in immunocompromised patients. Presence of commensals is also a warning that any other pathogens (including viruses) that may be present on the anaesthetist’s hands or in the environment may also contaminate the propofol. The presence of human commensals as well as environmental organisms in the propofol syringes are avoidable and a zero-contamination rate should be aspired to in all interactions with patients.
The prevalence of thrombocytopenia at a primary care HIV clinic in South Africa - possible implications for neuraxial anaesthesia
(Stellenbosch : Stellenbosch University, 2017-12) Steadman, Carl; Smit, Marli; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Anaesthetics and Critical Care.
ENGLISH ABSTRACT: South Africa has a high incidence of Human Immunodeficiency Virus (HIV) infection, and many of these patients will require surgery during their lives. The exact prevalence of thrombocytopenia in South African, HIV-infected patients (naïve/non anti-retroviral therapy naïve) are unknown. The reported global prevalence of thrombocytopenia in HIV positive patients ranges between 5.5 to 50% 17, 18. Neuraxial anaesthesia is contraindicated in patients with platelet counts of <75 x 109/L, due to the risk of neuraxial haematoma. The large variation in practice (in South Africa) in terms of preoperative special investigations (especially platelet count) in this patient population suggests that patients are either under investigated, or that unnecessary investigations are performed; with cost and time implications. This wide range in thrombocytopenia prevalence, together with the anaesthetic implications secondary to thrombocytopenia was the motivation behind us conducting an audit to determine the prevalence of thrombocytopenia in HIV positive patients. Our primary outcome was to determine the prevalence of thrombocytopenia in HIV-positive patients attending a primary care HIV clinic in the Western Cape, South Africa. Secondary outcomes were to: 1. Determine if there is any correlation between CD4 count and platelet count. 2. Determine what the influence of ART on platelet count is. 3. To make informal proposals regarding pre-operative special investigations (specifically platelet count) in the HIV positive patients. Our study, consisting of 1,410 patients, provided the following important results: The median CD4 count was 281 +/- 199 cells / mm3. Thirty-one percent of patients had a CD4 count of < 200 cells / mm3. The median platelet count was 270 +/- 100x109/L. The platelet count was < 150 x 109/L (thrombocytopenia) in 6.5%, and < 75 x 109 /L (severe thrombocytopenia) in 0.7% of participants. Thrombocytopenia was more common in patients with a CD4 count < 200 cells/mm3 (p <0.001) and in ART naïve patients (p = 0.02). However, there was no connection between severe thrombocytopenia and a CD4 count of < 200 cells / mm3 (p = 0.36) or ARV naivety (p = 0.66) Infection and malignancy had no significant impact on thrombocytopenia (p = 0.66, Fischer's exact 0.3) nor severe thrombocytopenia (p = 0.99, Fischer's exact 0.5). Conclusion: In this descriptive study, we found that the prevalence of severe thrombocytopenia to be very low (0.7%). We cannot make statistically supported deductions regarding this result because the prevalence of thrombocytopenia in the general population is unknown, and our study did not have a control group. However, we will propose that the following be kept in mind regarding preoperative special investigation decision making in HIV positive patients: 1. The incidence of neuraxial hematomas has not increased in conjunction with the increase in HIV positive patients, 2. The costs associated with special investigations. 3. The low prevalence of severe thrombocytopenia. 4. The lack of literature to support a safe cut-off for platelet count for neuraxial anaesthesia.
Reassessment of acute postoperative pain in a resource limited burns unit after the implementation of an analgesic management plan
(Stellenbosch : Stellenbosch University, 2017-12) Greyling, Adriaan Johann; Senekal, A. C.; Murray, A. A.; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Anaesthesiology and Critical Care.
ENGLISH ABSTRACT: Background Tygerberg Academic Hospital is the referral centre for all major burn wounds in adult patients in the Western Cape. Patients who underwent surgery for burns related injuries at Tygerberg Academic Hospital were identified as having a high incidence of moderate to severe postoperative pain in an audit done in 2012 when there was no fixed protocol for postoperative analgesia.1 In an attempt to reduce the incidence of moderate to severe postoperative pain, the Department of Anaesthesiology and Critical Care at Tygerberg Academic Hospital introduced a new postoperative analgesia protocol in the burns unit in November 2016. This is, according to our knowledge, the first unit in Tygerberg Academic Hospital where pain scores were introduced as part of routine vitals. Methods A five month interval after the introduction of the new protocol was allowed before an audit of patients’ pain experience was commenced. A sample of 64 patients that underwent burns related surgery was evaluated. Patients were asked to indicate on a printed visual analogue scale (VAS) the worst pain experienced in the first 24 hours postoperatively, as well as the amount of pain experienced at the time of the interview at 24 hours postoperatively. These values were compared to the data collected during the audit of 2012 to establish whether any improvement had been made. We considered a reduction in median VAS score of at least 18mm to be significant. Results In this study we could not prove a statistically significant difference between the control group of Murray and Retief from 2012 and the post-intervention group of 2017 in terms of pain outcome.

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