Browsing by Author "Dyer, Robert A"

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    A quality improvement project evaluating the perioperative implementation of a hypertension management protocol by anaesthesiologists at seven government hospitals in the Western Cape. “a multi-center, cross-sectional quality improvement project: the peri-operative implementation of a hypertension protocol by anesthesiologists”
    (2021) Pfister, Claire-Louise; Biccard, Bruce; Dyer, Robert A; Rayner, Brian
    BACKGROUND: Hypertension is a common risk factor for cardiovascular morbidity and mortality, with a high prevalence in patients presenting for elective surgery. In limited resource environments, patients have poor access to primary care physicians, limiting the efficacy of life-style modification for the initial management of hypertension in the community. In these circumstances, the perioperative period presents a unique opportunity for diagnosis and initiation and/or modification of pharmacotherapy of hypertension. Anesthesiologists are ideally placed to lead this aspect of perioperative medicine. METHODS: In collaboration with expert physicians, we designed and implemented an algorithm for the diagnosis of hypertension and subsequent initiation or modification of anti-hypertensive therapy, or referral to a physician. The study was a multi-center, cross-sectional quality improvement project in seven hospitals in the Western Cape, South Africa. On the day before scheduled elective surgery, adult inpatients had two sets of blood pressure (BP) readings taken, one by nurses and the other by anesthesiologists, using a noninvasive automated blood pressure device. These were averaged on an electronic database, to diagnose hypertension. Patients with normal BP or well-controlled hypertension required no further management. Those with borderline BP received educational pamphlets. Patients with stage 1 or 2 hypertension were managed with medication according to the algorithm, starting 1 day postoperatively, and provided with educational pamphlets. Patients with stage 3 disease were referred to a physician. The primary outcome was adherence by the anesthesiologist to the algorithm, defined as initiation of the prescribed medication. An 80% adherence rate was considered successful implementation. The secondary outcome was the issue of the antihypertensive medication at discharge. RESULTS: Two hundred and ninety-eight patients were screened for hypertension. One hundred and six patients were eligible for the quality improvement project. Thirty-seven (34.9%) had borderline blood pressure readings, 43 (40.6%) had stage 1-, 22 (20.8%) stage 2-, and 4 (3.8%) stage 3 hypertension respectively. The adherence rate by the anesthesiologist was 84.0% (95% confidence interval (CI) 77.0% to 91.0%) for initiation of anti-hypertensive therapy. It was noted that 55.5% (95% CI 46.2% to 65.1%) received their medication upon discharge. CONCLUSIONS: Anesthesiologists successfully implemented a quality improvement project for diagnosis and management of hypertension in the perioperative period. This has the potential to reduce the public health burden of hypertension in limited resource environments. Successful ongoing prescription and follow-up requires cooperation within a multi-disciplinary team involving anesthesiologists, surgeons, nurses, pharmacists and physicians.
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    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.
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    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.
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    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.
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    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.
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    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.
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    Haemodynamic consequences of Spinal Anaesthesia for non-emergency Caesarean section
    (2009) Dyer, Robert A; James, Michael Frank Mansel
    Single shot spinal anaesthesia for caesarean section is currently accepted as the favoured method in the absence of contraindications, for reasons of safety and comfort. Firstly, there is an increased risk of failed intubation associated with general anaesthesia. Secondly, spinal anaesthesia, if practiced correctly, allows for a superior experience of the delivery and improved bonding with the infant. Maternal haemodynamic stability is desirable both for maternal and neonatal safety, and to diminish maternal side-effects such as nausea and vomiting. Therefore, after an extensive literature review, clinically relevant aspects of spinal anaesthesia were studied, with a view to contributing to knowledge which could improve safety and outcome. The central themes explored in this thesis were fluid management during spinal anaesthesia for caesarean section in healthy parturients, the haemodynamic effects of the vasoactive agents ephedrine, phenylephrine and oxytocin during spinal anaesthesia for caesarean section in healthy patients and in patients with preeclampsia, and short term neonatal outcome after spinal anaesthesia in patients with severe preeclampsia. Research methodology included non-invasive measures as well as the use of a pulse wave form analysis monitor to measure maternal cardiac output. A validation study was performed comparing this method with thermodilution in patients with postpartum complications of preeclampsia. Abstract viii The results of these studies showed that: The pulse wave form monitor employed showed acceptable limits of agreement with the thermodilution method. Crystalloid coload was associated with lower vasopressor requirements than conventional preload. Spinal anaesthesia was associated with afterload reduction, which was more pronounced in healthy patients than in preeclamptics. Ephedrine maintained or increased, and phenylephrine reduced maternal cardiac output in healthy patients. Oxytocin was associated with transient haemodynamic instability in healthy and preeclamptic patients, which was obtunded by phenylephrine in the healthy population. Spinal anaesthesia for caesarean section was associated with a greater umbilical arterial base deficit than general anaesthesia in patients with preeclampsia. Overall, these studies should contribute to improved knowledge of haemodynamic responses during spinal anaesthesia for caesarean section, and ultimately to improved maternal morbidity and mortality.
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    Hypoxaemia during tracheal intubation in patients with hypertensive disorders of pregnancy: analysis of data from an obstetric airway management registry
    (2021) Smit, Maretha Isabel; Hofmeyr, Ross; du Toit, Leon; Dyer, Robert A
    Background In South Africa, hypertensive disorders of pregnancy are the leading cause of maternal mortality. More than 50% of anaesthesia-related deaths are attributed to complications of airway management. We compared the prevalence and risk factors for hypoxaemia (SpO2<90%) during induction of general anaesthesia in parturients with and without hypertensive disorders of pregnancy. We hypothesised that hypertensive disorders of pregnancy are associated with desaturation during tracheal intubation. Methods Data from 402 cases in a multicentre obstetric airway management registry were analysed. The prevalence of peri-induction hypoxaemia (SpO2<90%) was compared in patients with and without hypertensive disorders of pregnancy. Quantile regression of SpO2 nadir was performed to identify confounding variables associated with, and mediators of hypoxaemia.Results In the cohort of 402 cases, hypoxaemia occurred in 19% with and 9% without hypertension (estimated risk difference, 10%; 95% CI 2% to 17%; P=0.005). Quantile regression demonstrated a lower SpO2 nadir associated with hypertensive disorders of pregnancy as body mass index increased. Room-air oxygen saturation, Mallampati grade, and number of intubation attempts were associated with the relationship. Conclusions Clinically significant oxygen desaturation during airway management occurred twice as often in patients with hypertensive disorders of pregnancy, compounded by increasing body mass index. Intermediary factors in the pathway from hypertension to hypoxaemia were also identified.
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    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.
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    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.
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    Maternal and cardiac output response to vasopressor therapy during spinal anaesthesia for Caesarean Section in severe preeclampsia
    (2017) Daniels, Abigail Hanlise; Dyer, Robert A
    Background: The maternal haemodynamic responses to vasopressors during spinal anaesthesia for caesarean delivery in patients with severe preeclampsia, have not been accurately described. This study compared the haemodynamic effects of the vasopressors ephedrine and phenylephrine during spinal anaesthesia. Methods: Thirty nine women with treated severe preeclampsia presenting for spinal anaesthesia for caesarean section for a maternal indication, were studied. Baseline maternal haemodynamics were measured in the left lateral position, using minimal invasive cardiac output monitoring (LiDCOrapid). A 300 mL colloid preload was then administered. After standard spinal anaesthesia, 20 patients whose mean arterial pressure decreased to a predetermined target value were randomised to 2 groups of 10, to receive an initial bolus of either 7.5 mg ephedrine or 50 μg phenylephrine, and the haemodynamic responses recorded. The primary outcome was the percentage change in cardiac index. Results: Spinal hypotension in 20 patients was associated with an increase in mean cardiac output from baseline (mean difference 0.7 L/min, p<0.0001). In response to vasopressor, the mean [SD] percentage change in cardiac index was greater, and negative, in patients receiving phenylephrine versus ephedrine (-12 [7.3] vs 2.6 [6] L/min respectively, p=0.0001).] L/min respectively, p=0.0001). Post-vasopressor mean percentage change [SD] in heart rate and systemic vascular resistance (SVR) were higher in patients receiving phenylephrine (-9.1 [3.4] vs 5.3 [12.6], p=0.0027, and 22.3 [7.5] vs -1.9 [10.5] %, p<0.0001 respectively). Conclusions: Phenylephrine effectively reverses spinal anaesthesia-induced haemodynamic changes in severe preeclampsia, if left ventricular function is preserved.
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    Point-of-care ultrasound abnormalities in late onset severe preeclampsia: prevalence and association with serum albumin and brain natriuretic peptide
    (2018) Neethling, Elmari; Dyer, Robert A
    Abstract Background: Pilot studies applying point-of-care ultrasound (POCUS) in preeclampsia indicate the presence of pulmonary interstitial edema, cerebral edema, and cardiac dysfunction. Laboratory markers of oncotic pressure (albumin) and cardiac dysfunction (brain natriuretic peptide [BNP]) may be abnormal, but the clinical application remains unclear. We investigated the prevalence of pulmonary interstitial syndrome (PIS), cardiac dysfunction, and increased optic nerve sheath diameter (ONSD) in late onset preeclampsia with severe features. The primary aim was to examine the association between PIS or ONSD and maternal serum albumin level. The secondary aims were to explore the association between cardiac dysfunction and PIS, ONSD, BNP, and serum albumin level, and between POCUS-derived parameters and a suspicious or pathological cardiotocograph (CTG). Methods: Ninety-five women were enrolled in this prospective observational cohort study. A POCUS examination of lungs, heart and ONSD was performed. PIS was defined as a bilateral B-line pattern on lung US, and diastolic dysfunction according to an algorithm of the American Society of Echocardiography. ONSD > 5.8 mm was interpreted as compatible with raised intracranial pressure (> 20 mmHg). Serum BNP and albumin levels were also measured. Results: PIS, diastolic-, systolic dysfunction, and raised left ventricular end-diastolic pressure (LVEDP) were present in 23 (24%,) 31 (33%), 9 (10%), and 20 (25%) women respectively. ONSD was increased in 27 (28%) women. Concerning the primary outcome, there was no association between albumin level and PIS (p = 0.4) or ONSD (p=0.63). With respect to secondary outcomes, there was no association between albumin level and systolic dysfunction (p = 0.21) or raised LVEDP (p = 0.44). PIS was associated with diastolic dysfunction (p = 0.02), and raised LVEDP (p = 0.009, negative predictive value 85%). BNP level was associated with systolic (p < 0.001)- and diastolic dysfunction (p = 0.003) and LVEDP (p = 0.007). No association was found between POCUS abnormalities and a suspicious/pathological CTG (p = 0.07). Conclusion: PIS, diastolic dysfunction and increased ONSD were common in preeclampsia with severe features. Cardiac ultrasound abnormalities may be more useful than albumin levels in predicting PIS. The absence of PIS may exclude raised LVEDP. The further clinical relevance of PIS and raised ONSD remains to be established. BNP level was associated with cardiac ultrasound abnormalities. Although this study was not designed to directly influence clinical management, the findings suggest that POCUS may serve as a useful adjunct to clinical examination for the obstetric anesthesiologist managing these complex patients.
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    Quantification of cardiac structure and function using transthoracic echocardiography in term women with HIV
    (2017) Gibbs, Matthew Winton; Dennis, A T; Dyer, Robert A
    Introduction: In South Africa, up to 30% of pregnant women are human immunodeficiency virus (HIV) positive and morbidity and mortality is high in this group. HIV positive men and women may have multiple cardiovascular comorbidities, which include systolic dysfunction that may progress to heart failure secondary to dilated cardiomyopathy. However the concurrent effect of pregnancy and HIV infection on haemodynamics has not been extensively researched. The aims of this study were to quantify haemodynamics using transthoracic echocardiography (TTE) in term pregnant women with HIV on antiretroviral (ARV) treatment and compare the data with term healthy women in the same population. Method: After ethics approval and written consent, 30 consecutive term HIV positive women and 40 healthy term pregnant women were recruited. HIV positive women had a CD4 count greater than 200 and were either on Highly Active Anti-Retroviral Therapy (HAART) or single drug management. Results: Haemodynamic assessment was possible in all patients and women in the two groups were similar in age, and body mass index. Mean CD4 count was 452 ± 187.8 and duration of therapy was 15.9 ± 22.4 months. Compared with healthy pregnant women, women with HIV have systolic changes exhibited by reductions in left ventricle (LV) septal and right ventricle (RV) systolic myocardial velocities as well as increased LV end-diastolic (ED) areas and diastolic changes of increased RV isovolumetric (IV) relaxation and reduced RV e′ diastolic myocardial velocities. These changes occur in the presence of a reduced LV mass. Pericardial effusions occurred more frequently and are of a larger size in women with HIV. These findings suggest subclinical impairment of systolic function in the LV as well as subclinical impairment of both systolic and diastolic function in the RV. Discussion: Transthoracic echocardiography can quantify cardiac function in healthy pregnant women and in pregnant women with HIV and is acceptable to the patients. HIV positive pregnant women at term on anti-retroviral therapy have hearts that have subclinical systolic dysfunction in the presence of decreased LV mass and increased end-diastolic areas. This may represent a failure to compensate for the increased haemodynamic demands of pregnancy and may be as a result of the direct effects of HIV itself or due to anti-retroviral drugs.
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    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.
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    Spinal anaesthesia for brachytherapy for carcinoma of the cervix a comparison of two dose regimes of hypebaric bupivacaine
    (2011) Haus, Nikolas Jason; Dyer, Robert A
    The main purpose of the study was to help establish the best dose regimen of hyperbaric bupivacaine, when combined with intrathecal fentanyl, for spinal anaesthesia for brachytherapy for carcinoma of the cervix. This procedure is performed as a day case at Groote Schuur Hospital.
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    The impact of morbid obesity on cardiac structure and function in pregnancy
    (2018) Fernandes, Nicole Lucy; Dyer, Robert A
    Background: The increasing prevalence of obesity worldwide is a major threat to global health. Structural and functional changes in the heart are well documented for obesity as well as for pregnancy, but there is limited literature on the impact of obesity on cardiac function in pregnancy. We hypothesized that cardiac maladaptation to pregnancy occurs more frequently in otherwise healthy morbidly obese pregnant women than in pregnant women of normal body mass index (BMI). Methods: This prospective cohort study was performed in two referral maternity units in Cape Town, South Africa, over a 3-month period. Forty morbidly obese pregnant women (BMI ≥40 kg.m⁻²) (Group O) were compared to 40 pregnant women of BMI 30 kg.m⁻² (Group N). Cardiac structure and function were assessed by transthoracic echocardiography, according to the recommendations of the British Society of Echocardiography. Results: Acceptable echocardiographic images were obtained in all obese women. Statistical significance was defined as P< .005 after applying the Bonferroni correction for multiple comparisons. Mean [SD] mean arterial pressure was higher in Group O (91 [8.42] vs 84 [9.49] mmHg, P<0.001). There were no between-group differences in heart rate, cardiac output, or cardiac index (84 [12] vs 79 [13] beats.min⁻¹, P=0.103; 5447 [1048] vs 4740 [1183] mL.min⁻¹, P=0.006; 2551 [474] vs 2729 [623] mL.min⁻¹.m⁻², P=0.156, respectively). Stroke volume index was lower, and left ventricular mass higher in Group O (30.14 [4.51] vs 34.25 [7.00] mL.m⁻², P=0.003; 152 [24] vs 115 [29] g, P<0.001). Isovolumetric relaxation time was significantly prolonged in Group O (73 [15] vs 61 [15] milliseconds, P<0.001). The septal tissue Doppler index E' sept was lower in Group O (9.08 [1.69] vs 11.28 [3.18], P<0.001). There were no between- group differences in E' average (10.7 [2.3] vs 12.0 [2.7], P=0.018), or E/E' average (7.85 [1.77] vs 7.27 [1.68]). Conclusion: Obese pregnant women had a similar cardiac output and cardiac index to those with normal BMI. Their increased left ventricular mass and lower stroke volume index could indicate a limited adaptive reserve. Obese women had minor decreases in septal left ventricular tissue Doppler velocity, but the E/E' average values did not suggest clinically significant diastolic dysfunction.
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    The use of phenylephrine to obtund oxytocin induced hypotension and tachycardia during elective caesarean section
    (2016) Rumboll, Charles Knight; Dyer, Robert A
    Background: Oxytocin causes clinically significant hypotension and tachycardia. This study examined whether the prior administration of phenylephrine obtunds these unwanted haemodynamic effects. Methods: Forty pregnant women undergoing elective caesarean section under spinal anaesthesia were randomised to receive either a 50 μg bolus of phenylephrine (Group P) or saline (Group S) immediately prior to oxytocin (3 IU over 15 seconds). Systolic blood pressure [SBP], diastolic blood pressure [DBP], mean arterial pressure [MAP] and heart rate [HR]) were recorded using a continuous non-invasive arterial pressure device. Baseline values were averaged for 20 seconds post-delivery. Between-group comparisons were made of the mean peak changes in BP and HR, and the mean percentage changes from baseline, during the 150 seconds after oxytocin administration. Results: The mean peak percentage change (SD) in SBP was -16.9% (2%) in Group P, and -19.0% (1.9%) in Group S and the estimated mean difference was 2.1% (95% CI: -3.5 to 7.8 %) and P =0.44; corresponding changes in HR were 13.5% (2.3%) and 14.0% (1.5%) and the mean estimated difference was 0.5% (95% CI -6.0 to 5%) and P=0.87. The mean percentage change from the baseline measurements during the 150 s period of measurement was greater for Group S than Group P: SBP -5.9% vs -3.4%; P =0.149; DBP -7.2% vs -1.5%, P =0.014; MAP -6.8% vs -1.5%, P =0.007; HR 2.1% vs -2.4%, P =0.033. Conclusion: Intravenous phenylephrine 50 μg immediately before 3 U oxytocin during elective caesarean section does not prevent maternal hypotension and tachycardia.
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    The utility of occlusion of the pulse oximeter trace in the estimation of systolic blood pressure during spinal anaesthesia for caesarean section: the effect of body mass index
    (2016) Samuel, Theresa; Dyer, Robert A
    Background: We compared the accuracy and precision of estimation of the systolic blood pressure (SBP) by disappearance of the pulse oximeter trace (DOT), with noninvasive blood pressure (NIBP) measurement, across the range of body mass index (BMI), during spinal anaesthesia (SA) for caesarean section (CS). Methods: Three groups of 25 parturients were recruited, with BMI of < 30- (Group 1), 30-40- (Group 2), and > 40 kg/m2 (Group 3) respectively. SBP was measured using the DASH® 3000 monitor (GE Health Care, UK) NIBP monitor, placed on the same arm as the pulse oximeter probe. Estimations of SBP were done before- and 5 minutes after induction of SA, during cuff inflation and deflation. The times taken for the estimations and the actual NIBP measurements were noted. Bland and Altman analysis was performed and the correlation coefficient estimated. Results: Concerning the most clinically relevant estimation, namely SBP during inflation post-SA: For Groups 1, 2 and 3, r = 0.56, 0.74 and 0.91; bias = -0.4, -2.9 and 0.8 mmHg, and limits of agreement = -27.7 to 26.9, -27.7 to 21.9 and -15.9 to 17.5 mmHg respectively. The mean (SD) time required for estimation of the SBP during inflation post- SA was 7.5 (1.1) s, 11.8 (3.8) s and 16.8 (4.2) s in the Groups 1, 2 and 3 respectively. The mean (SD) time required for measurement of post-SA SBP during inflations in Groups 1, 2 and 3, was 30.3 (13.1) s, 41.3 (10.2) s and 49.8 (14.6) respectively. In the post-SA period, mean time saved by estimating SBP during inflation was approximately 28.5 seconds, compared with 9 seconds during deflation. The time saved in Groups 1, 2 and 3 was 22.8 (13.2) s, 30.0 (11.6) s and 33.0 (15.6) s respectively. In the BMI > 40 kg/m2 group, the percentage error is ±13% of the mean systolic blood pressure observed, and the absolute error is ±16 mmHg, compared to ±27 mmHg in the normal BMI group. Conclusion: Post-SA estimation of SBP during cuff inflation in morbidly obese patients is more accurate and precise than in the other BMI Groups. Time to estimation is shorter than measurement by a clinically relevant period (33 s). This should improve patient safety in morbidly obese parturients.
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    Validation of the use of short message service (SMS) as a training tool for anaesthetic nurses
    (2015) Duys, Rowan Alexander; Duma, Sinegugu; Dyer, Robert A
    Background: Anaesthetic nurses form a critical part of the team providing peri-operative care to patients, but no accredited training exists for them in South Africa. In this setting, without a formal training programme, short in-service training interventions are a pragmatic attempt at improving nurse performance and patient outcomes. Traditional didactic teaching formats have limitations, and mLearning (the use of mobile telephones to facilitate education) has proven equivalent or superior to traditional teaching methods in several settings. Despite very high levels of mobile phone ownership amongst healthcare workers in Africa, this form of educational delivery has not been tested in the hospital-based nursing population. Methods: A telephonic True/False Pre-Test was performed with 12 nurses of varying levels of training, to assess their pre-existing knowledge of anaesthesia. A pre-learning package was then delivered to them in the form of daily SMS’s for a month covering relevant anaesthesia content. A telephonic post-intervention test was performed to assess if anaesthesia theory knowledge had improved. Results: Median test scores were compared using a Wilcoxon Signed Rank test and were statistically higher in the post-intervention test: 83,3% (IQR 66,7-86,7) vs. 70% (IQR 66,7-71,7) (p=0,018). Conclusions: The results show that knowledge scores of hospital-based anaesthetic nurses can be improved using training by SMS, thus validating the use of the mobile phone as a cheap, widely accessible and effective educational vehicle.