DETERMINANTS OF THE LENGTH OF STAY IN INTENSIVE-CARE AND IN-HOSPITAL AFTER CORONARY-ARTERY SURGERY

Background-Patients who have coronary artery surgery normally occupy i ntensive care beds for less than 24 hours. Longer stays may result in under use of cardiac surgical capacity. One approach to optimise surgi cal throughput is prospectively to identify fast track patients-that i s, those who occupy an intensive care bed for less than 24 hours. A pr ospective audit of patients was performed to identify fast track patie nts by simple clinical criteria. Total length of hospital stay was als o assessed in an attempt to predict which patients were likely to have a short postoperative stay, defined as less than or equal to 7 days. Methods-Baseline demographic details, cardiovascular risk factors, ang iographic and operative details were recorded for 431 consecutive pati ents who underwent coronary surgery at a regional centre over a nine m onth period. Outcome measures were the duration of the stay in the int ensive care unit in hours and total duration of the postoperative stay in hospital in days. In addition, two groups of patients who were tho ught to be fast track were identified prospectively. Fast track 1 pati ents were identified by criteria selected by cardiovascular physicians . These were age less than 60 years, stable angina, good left ventricu lar function (ejection fraction > 50%), good renal function (serum cre atinine < 120 mu mol/l), and no obesity, diabetes, or other serious di sease. Fast track 2 patients were identified by criteria defined by ca rdiovascular surgeons. These were male sex, age less than 65 years, go od left ventricular function and no peripheral vascular disease, diabe tes, or other serious disease. The efficacy of both sets of criteria i n predicting outcome was tested. Results-344 (79.8%) patients were fas t track. Significant factors for the prediction of fast track patients by univariate analysis (with positive predictive accuracy and sensiti vity) were left ventricular ejection fraction > 50% (83%, 80%), left v entricular end diastolic pressure < 13 mm Hg (90%, 59%), creatinine le ss than 120 mu mol/l (83%, 87%), and one or two vessel coronary diseas e (89%, 34%). Of the patients categorised as fast track 1 89% proved t o be fast track (sensitivity 24%), however, the fast track 2 character istics were not significant. Age, sex, obesity, diabetes, hypertension , a history of obstructive pulmonary disease and unstable angina were not predictive of the duration of intensive care stay. Multivariate an alysis indicated that only left ventricular end diastolic and the numb er of diseased arteries predicted fast track patients. These criteria separated patients into three groups. Those who were good risk had one or two vessel disease and left ventricular end diastolic pressure < 1 3 nun Hg. They comprised 19% of the total and 93% of them were fast tr ack. Those who were intermediate risk had either three vessel disease or left ventricular end diastolic pressure > 13 mm Hg but not both. Th ey comprised 49% of the total and 85% of them were fast track. Those w ho were poor risk had both three vessel disease and left ventricular e nd diastolic pressure > 13 mm Hg. They comprised 32% of the total and 62% of them were fast track. The 106 (24%) patients who spent less tha n or equal to 7 days in hospital after surgery were significantly youn ger (mean (SD) 55(8) v 58(8) years; P < 0.001) with a lower incidence of previous myocardial infarction (positive predictive accuracy 30%, s ensitivity 53%), were less likely to have a history of obstructive pul monary disease (25%, 98%), and more likely to have one or two vessel c oronary disease (33%, 41%). They were more likely to have an internal mammary artery as a bypass conduit (27%, 89%) and more likely to need fewer than three distal anastomoses of the vein graft (29%, 63%). By m ultivariate analysis only age was significantly predictive of hospital stay. Total hospital stay could not be satisfactorily modelled on the basis of the criteria tested here. Sex, obesity, diabetes, hypertensi on, unstable angina, renal function, and left ventricular function wer e not associated with hospital stay. Conclusions-Most patients who had coronary artery surgery spent less than or equal to 24 hours in inten sive care, but most spent > 7 days in hospital. The chance of a patien t spending less than or equal to 24 hours in intensive care could be p redicted by the number of coronary arteries diseased and the left vent ricular end diastolic pressure. Poor risk patients (32%) had only a 62 % chance of an intensive care unit stay of less than or equal to 24 ho urs. A policy of scheduling no more than one such patient for surgery per day would be simple to institute and would maximise the use of sur gical capacity.