Ischemic heart disease, the leading cause of death worldwide, may result in devastating perioperative ischemia and infarction. The underlying pathophysiology, precipitating factors, and approach to prevention differ between patients presenting for noncardiac surgery, developing acute coronary syndrome versus stable angina. The first half of this article reviews the pathophysiology of acute coronary syndrome and stable angina. Acute coronary syndrome, otherwise known as Type 1 myocardial infarction, includes unstable angina, non-ST segment elevated myocardial infarction and ST segment elevated myocardial infarction. Acute coronary syndrome occurs as a result of vulnerable plaque rupture with subsequent varying degrees of thrombus formation, arterial spasm, and thus coronary occlusion. Stable angina, on the other hand, results from a myocardial oxygen delivery and demand mismatch in the setting of fixed coronary stenosis. After this discussion, the review article considers how both apply to perioperative myocardial infarctions and myocardial injury after noncardiac surgery. This article furthermore argues why myocardial oxygen delivery demand mismatch (Type 2) myocardial infarction is the most likely underlying pathophysiology responsible for perioperative myocardial infarctions. Being aware of this and knowledgeable about Type 2 infarctions may enable anesthetic providers to better predict the majority of triggers contributing to, and thus decreasing the incidence of, perioperative myocardial infarctions.

Objective: To assess the pressure flow relationship of the internal mammary artery (IMA) in situ, after skeletonisation and after anastomosis to the left anterior descending (LAD) coronary artery, using either halothane, sevoflurane or propofol as an anaesthetic agent. Methods: 15 Pigs were used in total, five received halothane, five sevoflurane and five propofol as an anaesthetic agent. The flow in the internal mammary artery in each of the pigs, was measured at various arterial pressures. This was done with the IMA in situ, then after dissecting the artery off the chest wall using the skeletonisation technique and finally after offpump grafting to the left anterior descending coronary artery. Results: The pressure flow relationship of the internal mammary artery after skeletonisation was found to be linear (r=0.8650). The pressure flow correlation after grafting the skeletonised internal mammary artery to the left anterior descending coronary artery was found to be similarly linear (r=0.8766). In the sevoflurane subgroup, with the IMA still in situ, a degree of autoregulation was found to be present, but after skeletonisation this was subsequently lost (p=0.011). Conclusions: The pressure flow relationship in the internal mammary artery after skeletonising the vessel and after OPCAB anastomosis to the LAD was found to be linear. In the subgroup of pigs receiving sevoflurane, some degree of autoregulation was demonstrated in the in situ IMA. This remnant of autoregulation was lost after skeletonisation and after grafting of the vessel to the left anterior descending coronary artery. SAHeart 2009; 6:222-228

Background: Neuraxial analgesia is currently considered to be the most effective method of intrapartum analgesia, causing little maternal and foetal sedation. While epidural analgesia has been well studied in developed countries, it is uncertain whether or not the results, particularly regarding complication rates, can be extrapolated to the South African public hospital context. Method: The available records for indications, complications and patient satisfaction of parturients receiving labour epidural analgesia at Tygerberg Hospital from 1 January to 31 December 2012 were reviewed in a retrospective one-year audit. Results: During the audited period, 157 (2.2%) of 7 005 parturients managed for labour and delivery at our hospital received epidural analgesia. One hundred and forty-nine records could be retrieved for analysis. Epidural analgesia was only used for medical indications and not patient demand. 73.2% of indications were cardiovascular disease and morbid obesity. Excluding a 13.4% incidence of hypotension, a 15.4% incidence of early complications [the majority (91.3%) being minor in nature] was observed. One (0.7%) potentially fatal incident of accidental systemic local anaesthetic administration and toxicity with cardiac arrest occurred. Parturients reported being “happy” or “very happy” (50% and 36%, respectively) with the epidural analgesia. Conclusion: Only 2.2% of parturients received labour epidural analgesia at a tertiary “developing world” hospital, primarily because of personnel constraints. Indications were predominantly cardiovascular disease and morbid obesity. Analgesia on demand was not provided. However, the incidence of complications from labour epidural analgesia was in keeping with that observed in developed countries. Most women were “happy” with their labour epidural analgesia.

Background: Neuraxial analgesia is currently considered the most effective method of labour analgesia. While well studied in developed countries, it is uncertain whether the results, particularly regarding epidural analgesia complication rates, can be extrapolated to the context of the South African public hospital.Method: A retrospective one-year audit reviewed available records for indications for-, complications of-, and patient satisfaction with labour epidural analgesia at Tygerberg Hospital, Western Cape.Results: During the period audited, 157 (2.2%) of 7 005 parturients received labour epidural analgesia. One hundred and forty nine records were retrieved for analysis. Epidural analgesia was not provided on patient request. Rather, specific indications for epidural analgesia in 73.2% of these cases were preeclampsia, cardiovascular disease and morbid obesity. The incidence of complications was 32.3%, comprising hypotension (13.4%) and all other complications (18.9%). Most complications were minor and self-limiting (97.9%). One serious adverse event (cardiac arrest) due to accidental intravenous infusion of bupivacaine was recorded. Resuscitation with lipid emulsion was successful. Parturients reported being " happy" or " very happy" (50% and 36% respectively) with epidural analgesia.Conclusions: At this tertiary referral hospital in the Western Cape, only 2.2% of parturients received labour epidural analgesia, possibly because of personnel time constraints. Indications comprised predominantly preeclampsia, cardiovascular disease and morbid obesity. The incidence of complications from labour epidural analgesia was in line with that observed in developed countries. Most patients were happy with their analgesia. This audit identifies an urgent need for improvement of the labour epidural service at this institution.

Anaesthetic and critical care staff play a governing role in the comprehension of a hospital's oxygen delivery system and associated contingency plans for internal disaster management. Therefore, staff must be thoroughly prepared and properly trained to support an institution-wide emergency response in the event of central oxygen pipeline failure.

Patients in critical care with lung injuries require oxygenation, but current methods are not applicable for all situations. The most common method, Extracorporeal Membrane Oxygenation is an expensive procedure and requires highly trained staff. Respiratory Assist Catheters (RACs) could be used as an alternative because they do not place extra stress on the lungs, are easy to implement, cost-effective and are available for immediate use in clinical settings or in first aid situations. This paper describes experiments and simulations to evaluate the feasibility of intravenously oxygenating the blood using microbubbles. The tests included in vivo and ex vivo tests using animal models to investigate both the dissolution times of the microbubbles as well as the physiological effects of an intravenously placed device. Numerical simulations based on the dissolution rate of oxygen in venous blood were also completed. The results indicate that the dissolution times for the micro bubbles are too slow for the device to be successful in clinical practice.

Under certain circumstances, the placement of arterial catheters can be difficult. In these instances, a form of guidance is preferred to avoid repeated insertions of the arterial catheter. Ultrasonic guidance is generally used in these instances, but the equipment required is expensive and cumbersome. This study produced an arterial catheter that is guided by the impedance of biological tissue encountered between the patient's skin and the lumen of the artery, with the aim of producing a cheaper and manageable alternative to ultrasonic guidance. Additionally, this study has inspected the impedance of human tissue in order to determine whether or not a sufficient and discernable difference between the impedance of the different tissue types could be identified and thus be used to guide an arterial catheter based on said impedance differences. The results indicate that the difference between subcutaneous tissue, fat tissue and skeletal muscle tissue are not clear enough to make accurate discrimination between tissue types. However, the study shows a clear difference between the impedance of arterial blood and the aforementioned tissue, allowing for the device to determine when accurate placement has been achieved. From the results obtained in the studies, the discrimination between blood and other intermediary tissue can be made with 99,4% confidence.

The Department of Anaesthesiology and Critical Care at Stellenbosch University lost a valued colleague and dear friend when Dr Pieter le Roux passed away on Wednesday, 27 March 2013.

OBJECTIVES:To compare the physiotherapy service provided when therapists' decisions are guided by an evidence-based protocol with usual care (i.e. patient management based on therapists' clinical decisions).DESIGN:Exploratory, controlled, pragmatic sequential time block clinical trial.SETTING:Level 3 surgical unit in a tertiary hospital in South Africa.PARTICIPANTS:All patients admitted consecutively to the surgical unit over a 3-month period were allocated to usual or protocol care based on date of admission.INTERVENTIONS:Usual care was provided by clinicians from the hospital department, and non-specialised physiotherapists were appointed as locum tenens to provide evidence-based protocol care.MAIN OUTCOME MEASURES:Patient waiting time, frequency of treatment sessions, tasks performed and adverse events.RESULTS:During protocol-care periods, treatment sessions were provided more frequently (P<0.001) and with a shorter waiting period (P<0.001). It was more likely for a rehabilitation management option to be included in a treatment session during protocol-care periods (odds ratio 2.34, 95% confidence interval 1.66 to 3.43; P<0.001). No difference in the risk of an adverse event was found between protocol-care and usual-care periods (P=0.34).CONCLUSIONS:Physiotherapy services provided in intensive care units (ICUs) when the decisions of non-specialised therapists are guided by an evidence-based protocol are safe, differ from usual care, and reflect international consensus on current best evidence for physiotherapy in ICUs. Non-specialised therapists can use this protocol to provide evidence-based physiotherapy services to their patients. Future trials are needed to establish whether or not this will improve patient outcome.

"Obituary: Prof Patrick Anthony Foster." Southern African Journal of Anaesthesia and Analgesia, 18(6), pp. 355–356

The authors report and discuss the anaesthetic management of a transvenous transcatheter tricuspid valve replacement. The conduct of anaesthesia, the challenges encountered and the specific risks associated with the procedure will be discussed. Percutaneous tricuspid valve replacement may be safely performed under general anaesthesia, provided that the procedure is understood and all possible eventualities considered. As the quality of percutaneous prostheses improves, and if longterm follow-up confirms this as a safe option, anaesthesiologists will be expected to provide perioperative care for a growing number of these cases.

Accidental intravascular administration of bupivacaine during performance of a brachial block precipitated convulsions followed by asystole. The patient was rapidly resuscitated using cardiopulmonary resuscitation, supplemented by 150 mL of 20% lipid emulsion. Nonetheless, cardiac toxicity reappeared 40 min after completion of the lipid emulsion. In the absence of further lipid emulsion, amiodarone and inotropic support were used to treat cardiotoxicity. This case suggests that local anesthetic systemic toxicity may recur after initial lipid rescue. Since recurrence of toxicity may necessitate administration of additional doses of lipid emulsion, a sufficient quantity of lipid emulsion should be available when regional anesthesia is performed.

To the Editor: Regarding the recent report by Marwick et al. describing a recurrence of local anesthetic cardiotoxicity after administration of intralipid, we suggest that the second episode of arrhythmias might be attributable to hypokalemia, rather than the cessation of the intralipid infusion. Sinus tachycardia accompanied by short bursts of ventricular tachycardia was noted 40 min after the conclusion of the intralipid infusion (approximately 70 min after the return of spontaneous circulation). The first and second blood gas analysis (5 and 110 min after the return of spontaneous circulation, respectively) showed potassium concentrations of 3.2 mEq/L (when the pH was 6.8), and 2.5 mEq/L (when the pH was 7.30). Hypokalemia could have resulted from the epinephrine infusion and the insulin and bicarbonate therapy instituted after the return of spontaneous circulation. Hypokalemia could also have been a preexisting condition contributing to the initial cardiac event. If hypokalemia preexisted, we wonder about the patient’s serum magnesium blood concentration and whether pancreatitis and/or liver dysfunction also was preexistent. Insulin-glucose-potassium infusion has been described as a potential treatment for local anesthetic toxicity in dogs. With the advent of intralipid as first line therapy for local anesthetic toxicity, insulin-glucose infusion is more likely to cause harm than benefit as seen in this case report. Furthermore, glucose infusion can worsen neurologic outcome after cerebral ischemia. In conclusion, we suggest that hypokalemia contributed to the second episode of cardiac arrhythmias noted by Marwick et al.