Browsing by Author "Swanevelder, Justiaan"

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    Open Access
    Magnesium recurarisation differences between no reversal, neostigmine/glycopyrrolate reversal and sugammadex reversal of neuromuscular block in an in vivo rat model
    (2016) Van den Berg, Maurits Matthew; Kellaway, Lauriston A; James, Michael F; Swanevelder, Justiaan
    The neuromuscular junction (NMJ) is a synapse with one of the highest safety margins in the human body. The use of neuromuscular blocking agents to inhibit neuromuscular transmission is sufficient to produce skeletal muscle paralysis, a mechanism used to facilitate muscle relaxation during surgery. Residual neuromuscular block postoperatively has been found to be a major risk factor for postoperative complications. Sudden reinstatement of neuromuscular block (recurarisation), through use of magnesium, has also been observed clinically. This has led to a reluctance to use magnesium postoperatively for fear of recurarisation. Recurarisation following reversal of neuromuscular blockade with neostigmine or sugammadex has not been evaluated in a formal study, and for this reason, this study investigated recurarisation after 30 mg/kg magnesium sulphate (MgSO4) following reversal of neuromuscular blockade with neostigmine, two dosages of sugammadex or when reversal was omitted. Prior to investigating recurarisation, the effects of magnesium on neuromuscular transmission in the absence of neuromuscular blocking agents was investigated, in order to determine a standard clinical dose that did not produce detectable, by Train-of-Four Ratio (TOF-R) or Twitch 1 height (%T1), neuromuscular impairment.
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    Open Access
    Penetrating cardio-thoracic injuries at a district level hospital in Cape Town South Africa : A retrospective case audit
    (2018) Hameed-Ikram, Sarwat; Nkanyiso, Hadebe; Swanevelder, Justiaan
    The Khayelitsha District Hospital (KDH) faces the difficult challenge of managing patients with high acuity penetrating cardiothoracic injuries, but without the full complement of resources to provide optimal care. At the time of this dissertation, we were unaware of the outcome of patients cared for at KDH, and of any potential modifiable risk factors that could improve their outcome. We therefore undertook a retrospective case audit to determine the outcome of patients presenting alive at our emergency unit with penetrating chest injuries (PCI). Objective: The objective of this study is to audit the KDH experience with penetrating chest injuries and to identify potential risk factors that predict outcomes in patients who sustain these injuries and require surgery at this district level hospital. The total study duration was 34 months. Methods: A retrospective review of all medical records of patients with PCI who were alive on presentation and had undergone surgery at KDH between 1st February 2012 and 31st December 2014 was undertaken .An audit was conducted on these files. During the audit, affected patient's clinical and physiological variables on admission, intra- and post-operative were collected and evaluated as potential predictors of outcome. This study also assessed a possible relationship between physiological parameters together with arterial blood gases (ABG) on presentation with immediate 48-hour mortality. The selected variables were: SBP (systolic blood pressure) <90 mmHg or >90 mmHg, palpable pulse, presence of a precordial stab wound, vascular injury, base deficit (BD) and lactate. A logistic regression analysis was performed to investigate the relationship between the selected variables and the 48-hour mortality. The relationship between fluid, BD and lactate was compared using Pearson correlation. Continuous data is presented as means ± standard deviations. Estimates for predictor variables are presented with odd's ratios (OR) and 95% confidence intervals (95% CI). Permission of this study was gained from human research ethics committee of University of Cape town. Results: Over the 34-month study period, a total of 646 patients were admitted to KDH with penetrating cardiothoracic trauma. Fifty-six patients required surgery at KDH. These results show that KDH had a PCI incidence of 5.1%, and that this was predominantly amongst males in the 15 - 24 year age group. Fifty-five patients were male and only one female. Of the 56 operated patients, 37 (66%) presented in hemorrhagic shock with SBP < 90mmHg. The mean amount of resuscitation fluid, which included both crystalloid and colloid, administered in the Emergency Room (ER) was 2481 ml per patient. Ten (17.8%) patients had a front room thoracotomy (FRT), with a mortality rate of 6 (60%). The overall mortality rate amongst operated patients was 16 (31.3%). Thirty-three patients (58.9%) had an isolated cardiac chamber injury and 23 (41.1%) had a vascular injury. Mortality amongst patients with isolated cardiac chamber injury was 5 (31.2%) and mortality among patients with isolated vascular injury was 7 (43.7%). Two patients sustained a combined cardiac and vascular injury with a mortality of 12.5%. The results of the logistic regression analysis revealed no statistically significant correlation between the selected predictors and 48-hour mortality (p-values: BP<90mmH p=0.27, palpable pulse p=0.181, precordial stab p=1.17, vascular injury p=0.38, BE p=0.98, Lactate p=0.06). Additionally, there was no statistically significant relationship between administered EC fluids and the acid base severity (Pearson correlation coefficient: BD r =0.091, Lactate r = -0.13). Conclusion: Physiological (blood pressure, pulse) and ABG parameters (lactate and base deficit) were not identified as significant risk factors for survival in the sample studied. The risk factor of isolated cardiac injury carried a better prognosis. Logistic regression analysis did not support the initial observation of higher mortality in patients with vascular injury. Additionally, there was no correlation between the severity of the acid base disturbance and the volume of fluid administered during resuscitation in ER. The outcomes of patients with PCIs presenting at KDH was within those published in the literature (range of published mortality: 17%-80%, survival 3-84%). The ideal predictor for PCI outcome in our cohort was indeterminate. Limitations of this study that include a small sample size and incomplete medical records, may have led to a type 2 error. A more comprehensive prospective study with meticulous record keeping is required to identify the factors that can influence the outcome of patients with PCI.
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    Quadruple valve replacement in a patient with severe rheumatic heart disease
    (2018-06-01) Adembesa, Isaac; Myburgh, Adriaan; Swanevelder, Justiaan
    We present a patient with rheumatic heart disease involving all the heart valves. An intraoperative transoesophageal echocardiography confirmed severe mitral stenosis, severe aortic regurgitation, severe tricuspid regurgitation and stenosis, and severe pulmonary stenosis. The patient underwent successful quadruple valve replacement during a single operation at the Groote Schuur Hospital, Cape Town, South Africa.
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    Transoesophageal echocardiography (TOE): contra-indications, complications and safety of perioperative TOE
    (2018-12-01) Hauser, Neil D; Swanevelder, Justiaan
    Transoesophageal echocardiography (TOE) has, in certain clinical situations, become an almost universal monitor and diagnostic tool. In the perioperative environment, TOE is frequently used to guide anaesthetic management and assist with surgical decision making for, but not limited to, cardiothoracic, major vascular and transplant operations. The use of TOE is not limited to the theatre environment being frequently used in outpatient clinics, emergency departments and intensive care settings. Two case reports, one of oesophageal perforation and another of TOE utilization in a patient having previously undergone an oesophagectomy, introduce the need for care while using TOE and highlight the need for vigilance. The safe use of TOE, the potential complications and the suggested contraindications are then considered together with suggestions for improving the safety of TOE in adult and paediatric patients.
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    Ultrasonographic circumferential strain pattern analysis of the cardiac septal wall in rodents with experimental pulmonary hypertension.
    (2023) Van Heyningen, Charl; Swanevelder, Justiaan
    Pulmonary arterial hypertension (PAH) remains a devastating disease. Early diagnosis remains challenging, but is associated with improved outcomes. Rodent models have been extensively used to investigate PAH. Ultrasonographic strain pattern analysis provides a novel method of assessing cardiac function, but difficulties in transthoracic imaging of the right heart are a barrier to its use in diagnosis of PAH. Segmental strain pattern analysis of the intraventricular septum circumvents this problem while still providing insight into right ventricular (RV) function. In this paper, the authors compare the septal strain pattern of rodents with chemically-induced PAH, to a known indicator of right heart pressures, pulmonary arterial acceleration time (PAAT). Method This was a secondary analysis of ultrasonographic data of rodents from a previous study with chemically-induced PAH. Strain pattern analysis was used to identify peak circumferential strain (CS) of the septal segment on short axis views via transthoracic echocardiography. PAAT was also measured. Regression analysis was performed to assess the relationship between the parameters. Results The relationship between CS and PAAT was linear (y = 7.1343 + -0.6118 x, p=0.001, R2 0.69). Rodents' predicted CS was equal to 0.59 + (-1.1 x PAATms). CS increased by 1.1% for every 1 ms decrease in PAAT. Conclusion In rodents with PAH, peak CS of the septal segment on short axis view can be used to predict PAAT, and thus be used as a measure of PAH. Peak CS can reliably and easily be measured using transthoracic echocardiography, and may be valuable in the investigation and management of PAH in humans. Further studies should be conducted.
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    Open Access
    Ultrasonographic circumferential strain pattern analysis of the cardiac septal wall in rodents with experimental pulmonary hypertension.
    (2023) Van Heyningen, Charl; Swanevelder, Justiaan
    Pulmonary arterial hypertension (PAH) remains a devastating disease. Early diagnosis remains challenging, but is associated with improved outcomes. Rodent models have been extensively used to investigate PAH. Ultrasonographic strain pattern analysis provides a novel method of assessing cardiac function, but difficulties in transthoracic imaging of the right heart are a barrier to its use in diagnosis of PAH. Segmental strain pattern analysis of the intraventricular septum circumvents this problem while still providing insight into right ventricular (RV) function. In this paper, the authors compare the septal strain pattern of rodents with chemically-induced PAH, to a known indicator of right heart pressures, pulmonary arterial acceleration time (PAAT). Method This was a secondary analysis of ultrasonographic data of rodents from a previous study with chemically-induced PAH. Strain pattern analysis was used to identify peak circumferential strain (CS) of the septal segment on short axis views via transthoracic echocardiography. PAAT was also measured. Regression analysis was performed to assess the relationship between the parameters. Results The relationship between CS and PAAT was linear (y = 7.1343 + -0.6118 x, p=0.001, R2 0.69). Rodents' predicted CS was equal to 0.59 + (-1.1 x PAATms). CS increased by 1.1% for every 1 ms decrease in PAAT. Conclusion In rodents with PAH, peak CS of the septal segment on short axis view can be used to predict PAAT, and thus be used as a measure of PAH. Peak CS can reliably and easily be measured using transthoracic echocardiography, and may be valuable in the investigation and management of PAH in humans. Further studies should be conducted.