The influence of mean arterial blood pressure during cardiopulmonary bypass on post-operation acute kidney injury in hypertensive patients

Introduction: Over a period of time, kidney blood vessels will be damaged in those patients suffering from hypertension. Objectives: This study aimed to investigate the effect of mean arterial pressure during cardiopulmonary bypass (CBP). Patients and Methods: The present observational prospective study was conducted on 90 high risk patients, having records of hypertension and being candidates for open heart surgery. Patients divided into three groups based on their mean arterial pressure (MAP), lower than 60 mmHg (first group), between 60 to 70 mm Hg (second group) and higher than 70 mm Hg (third group) respectively during cardiopulmonary bypass. Clinical outcomes being studied included cardiac surgery-associated acute kidney injury (CSA-AKI) (RIFLE class), serum creatinine levels, glomerular filtration rate (GFR) and urinary output up to 24 hours after the surgery. Results: Data related to 90 case-patients have been analyzed. There was no difference between the groups in terms of demographic information. Prevalence of AKI in preliminary course after cardiac surgery was different among the groups. AKI occurred in six patients (15%) of the first group, five patients (12.5%) of the second group and two patients (5%) of the third group (P = 0.03). There have been no differences in terms of serum creatinine levels, GFR and urinary output during 24 hours after cardiac surgery, among the groups. However, delta creatinine level and delta GFR were significant in those groups with MAP of lower than 60 mm Hg and also between 60-70 mm Hg. Conclusion: This study showed that MAP level during CBP directly affects occurrence of AKI in patients after open heart surgery. High risk patients such as those suffering from hypertension have to be constantly monitored during CBP regarding their MAP. We concluded that MAP drops to lower than 70 mm Hg has to be prevented in hypertensive patients.