Factors associated with acute kidney injury and mortality during cardiac surgery.

BACKGROUND: Cardiac surgery with cardiopulmonary bypass (CPB) is known to contribute towards the incidence of acute kidney injury (AKI) and peri-operative morbidity and mortality. There are several patient, anaesthetic and surgical factors that contribute to its occurrence. It is imperative to know the profile of a patient who is likely to develop this complication to mitigate for modifiable risks. This study aimed at describing a profile of AKI in an adult patient (over the age of 18 years) following cardiac surgery on CPB. Factors associated with the development of cardiac surgery-associated acute kidney injury (CSA-AKI) are described, as well as the relationship between CSA-AKI and in-hospital mortality. METHODS: This was a contextual, descriptive and retrospective single-centre study with data of 476 adult patients admitted post cardiac surgery between January 2016 and December 2017. Data were collected from Charlotte Maxeke Johannesburg Academic Hospital (CMJAH) in South Africa. All adult patients who presented for elective cardiac surgery (coronary artery bypass graft), valvular, aortic and other cardiac surgery on CPB were included. Peri-operative factors such as patient demographics, baseline renal function, co-morbid factors, length of CPB and aortic cross-clamp time, degree of hypothermia, use of assist devices, and post-operative serum creatinine (SCr) levels were collected. Incomplete essential peri-operative data and data for patients who presented on renal replacement therapy (RRT) already were excluded. AKI was defined by Kidney Disease Improving Global Outcomes (KDIGO) criteria. RESULTS: One hundred and thirty-five (28%) patients developed CSA-AKI and 20, 5 and 3% were in KDIGO 1, 2 and 3, respectively. Older age (p = 0.024), female gender (p = 0.015), higher serum creatinine level (p = 0.025), and lower estimated glomerular filtration rate (eGFR) (p = 0.025) were associated with the development of CSA-AKI, while a history of hypertension was predictive. Forty-six of the 476 patients died. Mortality rates were significantly higher in those with AKI compared to those without [28 (21%) vs 18 (5%), respectively (p = 0.001)]. The incidence was significantly worse in those with severe kidney injury, as evidenced by mortality rates of 44 versus 5% between KDIGO 3 and KDIGO 1 (p < 0.001). Pre-operative eGFR and CSA-AKI requiring RRT were significantly associated with mortality, while pre-operative eGFR was an independent predictor of mortality (hazard ratio 0.99, 95% confidence interval: 0.97-0.99, p = 0.019). CONCLUSIONS: A history of hypertension was predictive of the development of CSA-AKI, and pre-operative eGFR was an independent predictor of mortality in this cohort. Both factors are modifiable.

Audit of transfusion of blood products in paediatric congenital heart surgery on cardiopulmonary bypass.

BACKGROUND: Cardiac surgery is associated with peri-operative bleeding, which may result in the need for blood transfusion, particularly in paediatric congenital cardiac surgery on cardiopulmonary bypass (CPB). There is a necessity for regular auditing in order to improve practices. METHODS: Retrospective, contextual, descriptive data of 105 patients were collected for the period January to December 2014. RESULTS: The median age of patients was four (1-6) years, weight was 13 (8.4-20) kg, and mean lowest CPB haemoglobin level was 8.3 (1.5) g/dl. There was a statistically significant difference in median red packed cell (RPC), platelet and cryoprecipitate units per patient transfused across four RACHS (risk-adjusted classification for congenital heart surgery) categories (p = 0.03, p = 0.0013, p = 0.0001, respectively). There was a statistically significant correlation between transfused fresh frozen plasma units with CPB time (r = 0.2634, p = 0.0199) and RPC units (r = -0.4654, p < 0.001). CONCLUSIONS: Although no standardised transfusion guidelines were available, overall transfusion of blood products was comparable to reported practices.