Development of an organ procurement team in South Australia in response to COVID-19.

BACKGROUND: Due to the nature of border closures and quarantine requirements in Australia during the COVID-19 pandemic, the feasibility of interstate travel for organ retrieval created complex logistics. An organ procurement service in South Australia, to procure heart and lungs of local donors, was commenced to mitigate the impact of the travel restrictions imposed due to COVID-19. The purpose of this review was to examine the initial data and feasibility of the service. METHODS: A single unit, multi-site retrospective review from April 2020-August 2021 of all organ retrievals undertaken by the Flinders Medical Centre cardiothoracic service across Adelaide metropolitan area. Data was prospectively collected and analysed from the DonateLife South Australian centralized database. All data was de identified. RESULTS: A total of 25 organ procurements had been undertaken across 17 months since commencing the program. Total of 9 hearts and 16 bilateral lungs were procured with median age of donor of hearts 49 years (IQR 35.5-51. 5) and 60 years (IQR 44-72) for lung donation. Six organs were donated after determination of circulatory death and 19 after neurological determination of death. Median ischaemic time for heart donation was 4.4 h (IQR 3.0-5.8) and lung donation 4.4 h (IQR 3.4-6.1). All organs procured by the local South Australian team were successfully transplanted at the recipient site. Recipient sites included 8 in Victoria, 10 in New South Wales, 4 in Western Australia and 3 in Queensland. CONCLUSIONS: The necessity of flexibility within the field of cardiothoracic surgery is evident during the COVID-19 pandemic. The implementation of an organ retrieval service in South Australia has been successful with no apparent increased risk to successful transplant outcomes.

Circulating and Urinary miR-210 and miR-16 Increase during Cardiac Surgery Using Cardiopulmonary Bypass - A Pilot Study.

A pilot study to measure and compare blood and urine microRNAs miR-210 and miR-16 in patients undergoing cardiac surgery with cardiopulmonary bypass (CPB) and off-pump coronary artery bypass grafting surgery. Frequent serial blood and urine samples were taken from patients undergoing cardiac surgery with CPB (n = 10) and undergoing off-pump cardiac surgery (n = 5) before, during, and after surgery. Circulating miR-210 and miR-16 levels were determined by relative quantification real-time polymerase chain reaction. Levels of plasma-free haemoglobin (fHb), troponin-T, creatine kinase, and creatinine were measured. Perioperative serum miR-210 and miR-16 were elevated significantly compared to preoperative levels in patients undergoing cardiac surgery with CPB (CPB vs. Pre Op and Rewarm vs. Pre Op; p < .05 for both). There were increases of greater than 200% in miR-210 levels during rewarming and immediately postoperatively and a 3,000% increase in miR-16 levels immediately postoperatively in urine normalized to urinary creatinine concentration. Serum levels of miR-16 were relatively constant during off-pump surgery. miR-210 levels increased significantly in off-pump patients perioperatively (p < .05 Octopus on vs. Pre Op); however, the release was less marked when compared to cardiac surgery with CPB. A significant association was observed between both miR-16 and miR-210 and plasma fHb when CPB was used (r = -.549, p < .0001 and r = -.463, p < .0001 respectively). Serum and urine concentrations of hypoxically regulated miR-210 and hemolysis-associated miR-16 increased in cardiac surgery using CPB compared to off-pump surgery. These molecules may have utility in indicating severity of cardiac, red cell, and renal injury during cardiac surgery.

Rewarming Temperature During Cardiopulmonary Bypass and Acute Kidney Injury: A Multicenter Analysis.

BACKGROUND: Acute kidney injury (AKI) after cardiopulmonary bypass (CPB) is associated with a requirement for dialysis, a longer stay in the intensive care unit, a longer hospital length of stay, and mortality. An oxygenator arterial outlet temperature greater than 37°C has been reported to be associated with AKI; however, the influence of other rewarming temperatures is unclear. Using multicenter registry data, this study aimed to evaluate the role of CPB rewarming temperatures on AKI. METHODS: Data from 8,407 adult patients undergoing coronary artery bypass grafting (CABG) or valve repair or replacement, or a combination, were collected using the Perfusion Downunder Collaborative Database. Primary variables of interest were rewarming temperatures, defined as cumulative time the oxygenator arterial outlet temperature was greater than 36°C, greater than 36.5°C, or greater than 37°C. Propensity scores were calculated to determine the predicted probability of hyperthermic perfusion (rewarming temperature >37°C). The influence of temperature on AKI was determined using separate multivariate models adjusting for propensity score in the entire cohort (n = 6,904) and in propensity-matched patients (n = 2,044). RESULTS: Overall, 11.8% of patients acquired AKI. The duration of rewarming temperature greater than 36°C or 36.5°C was not associated with AKI. The duration of rewarming temperature greater than 37°C (hyperthermic perfusion) was independently associated with RIFLE (Risk, Injury, Failure, Loss, End-stage renal disease) risk classification or greater (odds ratio [OR], 1.42; 95% confidence interval [CI], 1.09-1.77; p = 0.012) and injury classification or greater AKI (OR, 1.52; 95% CI, 1.09-1.97; p = 0.016) in the entire cohort, and injury classification or greater AKI (OR, 1.51; 95% CI, 1.15-1.90; p = 0.006) in propensity-matched patients. CONCLUSIONS: The duration of hyperthermic perfusion-rewarming temperature greater than 37°C-was an independent predictor of AKI. Avoidance of hyperthermic perfusion may be more beneficial in reducing AKI than avoidance of rewarming.

Mending a broken heart but breaking the kidney.

The incidence of acute kidney injury (AKI) is a frequent and serious complication of cardiac surgery. In 2013, 95% of cardiac surgical procedures performed in Australia and New Zealand used cardiopulmonary bypass (CPB). AKI following CPB is well known, yet the perioperative factors contributing to its development are incompletely understood. AKI following CPB has significant implications on both short-term and long-term outcomes. The techniques for conducting CPB have evolved, moving towards evidence-based practice; however, there is still no generally accepted definition of optimal perfusion and its conduct. This review examines the current incidence of AKI following cardiac surgery and the short-term and longer-term effects of AKI on morbidity and mortality. The purpose of this review is to discuss the perioperative risk factors related to CPB and their contribution to the development of AKI. This review will also discuss outcomes in regard to off-pump cardiac surgery, the role of remote ischaemic preconditioning on AKI and outcomes in patients with chronic renal failure undergoing cardiac surgery.

Remote ischaemic preconditioning: closer to the mechanism?

Brief periods of ischaemia followed by reperfusion of one tissue such as skeletal muscle can confer subsequent protection against ischaemia-induced injury in other organs such as the heart. Substantial evidence of this effect has been accrued in experimental animal models. However, the translation of this phenomenon to its use as a therapy in ischaemic disease has been largely disappointing without clear evidence of benefit in humans. Recently, innovative experimental observations have suggested that remote ischaemic preconditioning (RIPC) may be largely mediated through hypoxic inhibition of the oxygen-sensing enzyme PHD2, leading to enhanced levels of alpha-ketoglutarate and subsequent increases in circulating kynurenic acid (KYNA). These observations provide vital insights into the likely mechanisms of RIPC and a route to manipulating this mechanism towards therapeutic benefit by direct alteration of KYNA, alpha-ketoglutarate levels, PHD inhibition, or pharmacological targeting of the incompletely understood cardioprotective mechanism activated by KYNA.

Should Air Bubble Detectors Be Used to Quantify Microbubble Activity during Cardiopulmonary Bypass?

Air bubble detectors (ABDs) are utilized during cardiopulmonary bypass (CPB) to protect against massive air embolism. Stockert (Munich, Germany) ABD quantify microbubbles >300 µm; however, their reliability has not been reported. The aim of this study was to assess the reliability of the microbubble data from the ABD with the SIII and S5 heart-lung machines. Microbubble counts from the ABD with the SIII (SIII ABD) and S5 (S5 ABD) were measured simultaneously with the emboli detection and classification (EDAC) quantifier in 12 CPB procedures using two EDAC detectors and two ABDs in series in the arterial line. Reliability was assessed by the Spearman correlation co-efficient (r) between measurements for each detector type, and between each ABD and EDAC detector for counts >300 µm. No correlation was found between the SIII ABD (r = .008, p = .793). A weak negative correlation was found with the S5 ABD (r = -.16, p < .001). A strong correlation was found between the EDAC detectors (SIII; r = .958, p < .001), (S5; r = .908, p < .001). With counts >300 µm, the SIII ABDs showed a correlation of small-medium effect size between EDAC detectors and ABD1 (r = .286, p < .001 [EDAC1], r = .347, p < .001 [EDAC2]). There was no correlation found between ABD2 and either EDAC detector (r = .003, p = .925 (EDAC1), r = .003, p = .929 [EDAC2]). A correlation between EDAC and the S5 ABD, was not able to be determined due to the low bubble count detected by the EDAC >300 µm. Both SIII ABD and S5 ABD were found to be unreliable for quantification of microbubble activity during CPB in comparison with the EDAC. These results highlight the importance of ensuring that data included in the CPB report is accurate and clinically relevant, and suggests that microbubble counts from devices such as the SIII ABD and S5 ABD should not be reported.

Minimally invasive mitral surgery: dangerous to dabble.

The introduction of any new surgical technique is fraught with dangers and difficulties, and in cardiac surgery, these potential negative outcomes are magnified by inherent small margins for error. Buxton's law states that it is always too early for rigorous evaluation (of a new technique) until, unfortunately, it is suddenly too late (1). This insightful statement was used to describe the phenomenon to often seen in the introduction of new technologies or procedures in medicine. There is a natural reluctance to subject new techniques to standardized assessment too early in the introductory phase in an attempt to avoid negatively biased results while operator learning is still occurring (2). Over the last two or three decades, this phenomenon has been described as the learning curve and has most often been applied to minimally invasive surgery of all specialties, including general surgery, gynecology, and cardiothoracic surgery. Buxton's concern was justified, because by the time the procedure has become well practiced, there is a reluctance to subject it to rigorous trials on the argument that this will deny the latest, and perhaps greatest, treatment to patients. Whereas each argument, pre-emptive assessment, or delaying access is valid in isolation, the combination is a dangerous system to follow because it prevents rigorous evaluation and denies best practice.

The future of the perfusion record: automated data collection vs. manual recording.

The perfusion record, whether manually recorded or computer generated, is a legal representation of the procedure. The handwritten perfusion record has been the most common method of recording events that occur during cardiopulmonary bypass. This record is of significant contrast to the integrated data management systems available that provide continuous collection of data automatically or by means of a few keystrokes. Additionally, an increasing number of monitoring devices are available to assist in the management of patients on bypass. These devices are becoming more complex and provide more data for the perfusionist to monitor and record. Most of the data from these can be downloaded automatically into online data management systems, allowing more time for the perfusionist to concentrate on the patient while simultaneously producing a more accurate record. In this prospective report, we compared 17 cases that were recorded using both manual and electronic data collection techniques. The perfusionist in charge of the case recorded the perfusion using the manual technique while a second perfusionist entered relevant events on the electronic record generated by the Stockert S3 Data Management System/Data Bahn (Munich, Germany). Analysis of the two types of perfusion records showed significant variations in the recorded information. Areas that showed the most inconsistency included measurement of the perfusion pressures, flow, blood temperatures, cardioplegia delivery details, and the recording of events, with the electronic record superior in the integrity of the data. In addition, the limitations of the electronic system were also shown by the lack of electronic gas flow data in our hardware. Our results confirm the importance of accurate methods of recording of perfusion events. The use of an automated system provides the opportunity to minimize transcription error and bias. This study highlights the limitation of spot recording of perfusion events in the overall record keeping for perfusion management.