[Immediate hypertensive flare-up after coronary bypass. A predictable complication]

An immediate post-operative rise in blood-pressure occurred in 44% of 191 patients undergoing coronary bypass. In a retrospective study of the patients' records, the authors have endeavoured to determine which of the 23 parameters characteristic of each patient was predictive of post-bypass hypertension. Using a Bayesian discriminant analysis method, they found that the only variables predictive of hypertension in 86% of the cases were an history of myocardial infarction and the urinary sodium/ potassium ratio. When combined, an urinary Na/K ratio below 1 and the absence of previous infarction constitute a good index of possible post-operative rise in blood pressure.