published_or_final_version / Medicine / Master / Doctor of Medicine

Thesis ( M. Tech. (Clinical Technology )) - Central University of Technology, Free State, 2013 / The best approach to surgical myocardil revascularization remains controversial. It is already known that an inflammatory response exists due to several factors related to the use of CPB. physiological stress response which leads to an increase in pro-inflammatory markers still remains during OPCAB surgery. surgery induces a wide haematological and hemodynamic changes. Hemodynamic and metabolic optimization is of daily importance in the hospital environment. morbidity and mortality. Lactate is also often used to predict clinical outcomes and complications but controversy remains about using this measure because of discrepancies in The aim of the study was to evaluate how metabolic and clinical changes relate to the incidence of complications and clinical outcomes in ACS patients undergoing on-pump and off-pump CABG Sixty patients diagnosed with ACS who received CABG surgery were recruited to participate in the study (30 patients on-pump and 30 patients off-pump). Patients not receiving isolated with reference to the intra-operative and post-operative metabolic data, intra-operative hemodynamic data and post-operative clinical outcomes/complications. lactate levels <5mmol/L or patients with lactate levels >5mmol/L. Comparisons between the two groups were made with reference to the intra-operative and post-operative metabolic data, Intra-operative metabolic data indicated 11 (37.0%) on-pump patients and 6 (20.0%) off-pump patients had peak lactate levels of >5mmol/L during cardiac surgery. The difference between the statistically comparison, the difference cannot be considered clinically relevant. differences (p<0.05) between the lactate < 5mmol/L group and the lactate > 5 mmol/L group. Intra-operative hemodynamic data showed statistically significant differences between the on- Post-operative metabolic data showed statistically significant differences (p<0.05) between the on-pump and off-pump groups for acid-base balance variables, pH, HCO3- and BE (B) from The metabolites, glucose and lactate, showed statistically significant differences (p<0.05) between the on-pump and off-pump groups from admission to ICU until 12 hours post- Despite the fact that elevated lactate levels have been described to be associated with adverse outcomes in paediatric- as well as general intensive care admission, no specific lactate level has surgery. Lactate values for the on-pump group were significantly higher during the immediate post- resulting in vasoconstriction and a redistribution of blood flow away from the peripheral tissue and the splanchnic circulation, creating an environment for increased lactate levels in the tissue. indication of a patient's likelihood of experiencing various complications. Both groups recovered to lactate levels of <2mmol/L by the 24th hour post-operatively. According to operatively this is associated with an increased 60-day mortality. The study did show a statistically significant difference between the on-pump and off-pump comparison, the difference cannot be considered conclusive and we can only make suggestions as to the trends seen in the data. Elevated lactate levels show that they may be poorly correlated with clinical outcomes and in order to see a more definite relationship between peak lactate levels and clinical outcomes, a larger study population will be required or perhaps a different lactate cut-off value should be considered. It may also be more useful to see if there is a positive correlation between the duration of time a patient is subjected to peak lactate levels of >5mmol/L and clinical outcomes. We recommend larger study population and change lactate cut-off value to >10mmol/L.

Thesis (M. Tech. (Biomed. Tech.)) -- Central University of Technology, Free State, 2010 / The World Health Organization (WHO) has warned in 2005 that: “Coronary heart disease is now one of the leading causes of death worldwide. It is on the rise and has become a true pandemic that respects no borders” (WHO, 2005). The Heart and Stroke Foundation of South Africa more specifically estimates that approximately 33 (thirty‐three) people per day will die of a heart attack in South Africa. Despite the already high death toll resulting from AIDS in South Africa, death from a chronic disease, also including heart disease, will increase from 565 deaths per day in the year 2000, to 666 deaths per day by 2010 (Steyn, 2007). Acute coronary syndrome (ACS) is an ‘umbrella term’ describing a heterogeneous spectrum of clinical symptoms compatible with acute myocardial ischaemia (Monaco, Mathur, Martin, 2005; ACC/AHA, 2007) and an ongoing inflammatory process resulting from atherosclerosis. ACS can either be treated medically (pharmacological treatment), by percutaneous coronary intervention (PCI), or by performing coronary artery bypass graft (CABG) surgery either through on‐pump or offpump CABG surgery. By treating the ACS patient by means of CABG surgery, an inflammatory response is further triggered on top of the already existing inflammation resulting from atherosclerosis. This leads to a systemic inflammatory response (SIR), which may eventually lead to systemic inflammatory response syndrome (SIRS). This study focuses on the inflammatory response initiated by the CABG technique applied during the revascularisation of the ACS patient. Many past studies compared on‐pump and off‐pump CABG surgery, arguing not only the advantages and disadvantages of these surgeries, but also the outcomes regarding SIRS. Both types of surgery are associated with an inflammatory response resulting from tissue trauma and the use of the extracorporeal circulation (EC) in CABG surgery (Quaniers, Leruth, Albert, Limet, Defraigne, 2006). This non‐randomised, observational study primarily aimed to assess and compare the pre‐ and the post‐operative inflammatory markers between (n=60) patients with ACS undergoing either on‐pump CABG (n=30) or off‐pump CABG surgery (n=30). A secondary objective was to ascertain whether a correlation exists between the pre‐operative risk factors, the surgical procedure and the pre‐ and post‐operative inflammatory markers. Three inflammatory markers ‐ full blood count (FBC), procalcitonin (PCT) and C‐reactive protein (CRP) ‐ were analysed employing normal routine laboratory analysis. Interleukin‐6 (IL‐6) and tumour necrosis factor alpha (TNF‐α) were analysed using an enzyme amplified sensitivity immunoassay (EASI) method. The inflammatory markers were analysed pre‐operatively (baseline) and post‐operatively and at different time intervals (24, 48, 72, 96 and 120 hours post‐operatively). Pre‐operatively, all the leucocytes were already elevated in both CABG groups, as could be expected in patients with ACS resulting from the already existing atherosclerotic process and the consequent pre‐operative existing inflammatory response. A significant pre‐operative difference was moreover detected in respect of the lymphocytes between the two CABG groups (p=0.03024). A significant post‐operative difference was also detected between the two CABG groups. The following significantly elevated levels were detected in the on‐pump CABG surgical group: for WCC at 24 hours (p=0.00761), 48 hours (p=0.01520) and 72 hours (p=0.00004); for neutrophils at 24 hours (p=0.17422), 96 hours (p=0.18611) and 120 hours (p=0.12872); for lymphocytes at 48 hours (p=0.04829) and at 96 hours (p=0.01982); and, for PCT at 24 hours (p=0.00811), 48 hours (p=0.00966) and 72 hours (p=0.01823) . However, measurable values of IL‐6 levels were found to be higher in the off‐pump CABG surgical group, with significant differences manifesting between the two CABG groups at 96 hours (p=0.05352) and 120 hours (p=0.09729). No differences between the two groups could be demonstrated for eosinophils, basophils, monocytes, CRP and TNF‐α. In conclusion: despite the demonstrable inflammatory responses in both CABG groups, no difference in clinical outcomes was observed. The inflammatory responses evoked by on‐pump and off‐pump CABG procedures will, for some time to come, remain an area of interest for future research, but they are certainly not the only factors to have a bearing on surgical outcomes. The impact of intraoperative events needs to be elucidated further ‐ and in more detail ‐ in order to attempt to determine the relationship of these events on the extent of inflammatory responses and clinical outcomes, irrespective of whether the procedure is performed with or without cardiopulmonary bypass.

Thesis (M. Tech. (Clinical technology)) - Central University of technology, Free State, 2012 / The objective of this study was to investigate whether intra-operative regional cerebral tissue oxygen saturation (NIRS) and hemodynamic monitoring in patients with Acute Coronary syndrome (ACS) during coronary bypass graft surgery (CABG on-pump vs. off-pump) can predict clinical outcomes and complications. Data from 60 CABG patients (30 on-pump and 30 off-pump) were analyzed. The regional cerebral tissue oxygen saturation was monitored by using near-infrared spectroscopy (NIRS). The sensors were positioned in the middle of the patient's forehead and the cables were connected to the sensors and to the INVOS 5100C® Oximeter. According to NIRS values obtained, patients were subdivided into two groups. Patients in Group 1 had absolute NIRS values more than 50 or less than a 20% drop from the baseline value. Patients in Group 2 had absolute NIRS values of less than 50 or a drop of more than 20% from the baseline value. The lowest value recorded during the procedure was recorded for this purpose, irrespective of the time this value was obtained. Intra-operative hemodynamic monitoring was captured by a computer software program (Supplier Datex Ohmeda, South Africa). In order to describe surgical outcomes several parameters were analysed and compared. This included a Pre- and Post-operative Mini-Mental state examination that was performed to identify neurological outcomes or impairment. The NIRS values and trends in relation to renal function (U&E and creatinine, urine output, and urine electrolytes), as well as clinical outcomes were analyzed post-operatively for the different groups. Clinical outcomes were described using the Society of Thoracic Surgeons Database (STS database) data fields, and specifically the recording of complications. The overall clinical outcomes were analysed between the on-pump and off-pump groups as well as the NIRS results between the two groups. In order to elucidate the predictive role of NIRS the patients were divided into groups with either impaired /reduced NIRS values or acceptable NIRS values according to published results where a reduction of more than 20% from baseline or absolute values of less than 50 were associated with inferior outcomes. Finally, the predictive value of NIRS was evaluated within the on- and then the off-pump groups. In this analysis the outcomes of patients with reduced NIRS values was compared to those of patients with acceptable NIRS values. The study demonstrated that by far the majority of patients with reduced cerebral flow/oxygen delivery as reflected in cerebral NIRS, had on-pump CABG procedures (84% fell in risk group 2). It also showed that a NIRS reduction of more than 20 % from baseline and values of less than 50, has an impact on post–operative renal function. Monitoring of cerebral oximetry intra-operatively by using near-infrared spectroscopy during cardiac surgery (especially in on-pump cardiac surgery patients) allows the perfusionist and anaesthesiologist to detect cerebral desaturation and to intervene as necessary. This study also showed a tendency towards less renal function impairment in patients with absolute NIRS values > 50 or where there was < 20% drop from baseline. It is probably important to consider studying the time spend below 50 or a drop of more than 20% from baseline NIRS values, or the “area under the curve” as a specific factor contributing to the increased risk for post-operative complications applied on an increased study population. The study supports the routine use of NIRS as a non-invasive trend monitor of cerebral saturation and certainly initiated interventions by both anaesthetic and perfusion staff which contributed to excellent clinical outcomes in this research study.

This project offers evidence and data to measure how progressive and sustained mobilization strategies that are implemented by nurses impact early discharge on a single stay Cardiothoracic Intensive Care Unit for patients undergoing first-time Coronary Artery Bypass Surgery (CABG) surgery.