Nonneurologic morbidity and profound hypothermia in aortic surgery.
BACKGROUND
Use of profoundly hypothermic cardiopulmonary bypass may increase the risk of postoperative bleeding and lung and renal dysfunction. The aim of this study was to analyze postoperative blood loss and indices of pulmonary and renal dysfunction in patients undergoing proximal aortic surgery with and without the use of profound hypothermia to determine risk factors for nonneurologic morbidity.


METHODS
Risk factors for blood loss, transfusion requirement, and pulmonary and renal dysfunction were studied in 116 patients undergoing thoracic aortic surgery with profoundly or moderately hypothermic cardiopulmonary bypass.


RESULTS
Overall mortality was 8.6%. Mean (+/- standard deviation) cardiopulmonary bypass times were 191 +/- 53 minutes (profoundly hypothermic group) and 131 +/- 48 minutes (moderately hypothermic group; p < 0.0001). The incidence of blood loss more than 1 L or resternotomy for bleeding was 25% (29 patients). Fifteen patients (12.9%) experienced postoperative pulmonary dysfunction, and 25 patients (21.6%) had postoperative renal dysfunction. Forty-one patients (35.3%) had a prolonged intensive therapy unit length of stay. Multivariate analysis demonstrated that prolonged cardiopulmonary bypass time was the only predictor of postoperative hemorrhage and resternotomy for bleeding (p = 0.03). Increased intensive therapy unit length of stay was predicted by total arch replacement (p = 0.01) and low 6-hour ratio of partial pressure of arterial oxygen to inspired fraction of oxygen (p = 0.05). Increased preoperative creatinine (p = 0.002) and emergency status (p = 0.015) predicted postoperative renal dysfunction. Low 6-hour ratio of partial pressure of arterial oxygen to inspired fraction of oxygen was predicted by increased preoperative creatinine (p = 0.03) and prolonged cardiopulmonary bypass time (p = 0.03).


CONCLUSIONS
Profound hypothermia may cause a coagulopathy, but procedure extent is the primary determinant of postoperative bleeding. Profoundly hypothermic cardiopulmonary bypass does not appear to be a risk factor for renal or early pulmonary dysfunction or intensive therapy unit length of stay.
Cardiothoracic Surgical Unit, University Hospital Birmingham, Queen Elizabeth Medical Centre, Birmingham B15 2TH, United Kingdom.
Deborah K
DK
Harrington
Jean P
JP
Lilley
Stephen J
SJ
Rooney
Robert S
RS
Bonser
D058186:Acute Kidney Injury / Q000453:epidemiology / Q000209:etiology; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000768:Anesthesia, General; D001013:Aorta, Thoracic / Q000601:surgery*; D016063:Blood Loss, Surgical; D001803:Blood Transfusion; D002305:Cardiac Tamponade / Q000453:epidemiology / Q000209:etiology; D002315:Cardiopulmonary Bypass / Q000009:adverse effects*; D003422:Critical Care / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D007036:Hypothermia, Induced / Q000009:adverse effects* / Q000379:methods; D000860:Hypoxia / Q000097:blood / Q000453:epidemiology / Q000209:etiology; D007902:Length of Stay; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D010313:Partial Pressure; D011183:Postoperative Complications / Q000453:epidemiology* / Q000209:etiology; D019106:Postoperative Hemorrhage / Q000453:epidemiology / Q000209:etiology; D012120:Respiration Disorders / Q000453:epidemiology / Q000209:etiology; D012189:Retrospective Studies; D012307:Risk Factors
D010100:Oxygen