The value of pulmonary function testing prior to bariatric surgery.
BACKGROUND
Pulmonary function tests (PFTs) are often abnormal in the morbidly obese and improve after bariatric surgery. Our aim was to determine the utility of obtaining preoperative PFTs in assessing postoperative risk.


METHODS
146 consecutive patients undergoing open bariatric surgery were analyzed. Patients were divided into those who had postoperative complications (Group A, n=27) and those who did not (Group B, n=119). PFTs and BMI were compared between Groups A and B. PFT parameters are reported as the median percentage of age-matched controls.


RESULTS
Patients in Group A compared to Group B were heavier (BMI 58 vs 51 kg/m(2), P=.001) and older (46 vs 40 years, P=.02) than those in group B. They had reduced forced vital capacity (80% vs 97%, P<.001) and forced expiratory volume in 1 second (84% vs 99%, P=.002). They also had reduced vital capacity (VC, 85% vs 102%, P<.001) and total lung capacity (89% vs 99%, P=.01). They had decreased maximal voluntary ventilation (93% vs 106%, P=.003). They had lower arterial pO(2) (76 mmHg vs 85 mmHg, P=.001) and higher arterial-alveolar gradient (23 vs 17, P=.007). The strongest predictors of postoperative complications on multivariate analysis were reduced VC (RR 2.29 for each 10% decrease in VC, P=.0007) and age (RR 6.4 for age >40 years, P=.01).


CONCLUSIONS
PFTs help to predict complications after bariatric surgery. The greatest reduction in VC may occur in patients with central obesity, reflecting increased intrabdominal pressure and diminished chest wall compliance.
Hamoui
Nahid
N
Department of Surgery, University of Southern California, Los Angeles, CA 90033, USA.
Anthone
Gary
G
Crookes
Peter F
PF
D000328:Adult; D000367:Age Factors; D050110:Bariatric Surgery; D015992:Body Mass Index; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008168:Lung / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009767:Obesity, Morbid / Q000503:physiopathology* / Q000601:surgery*; D011183:Postoperative Complications / Q000453:epidemiology*; D011237:Predictive Value of Tests; D011300:Preoperative Care; D012129:Respiratory Function Tests; D012307:Risk Factors; D012720:Severity of Illness Index; D012737:Sex Factors; D014109:Total Lung Capacity; D014797:Vital Capacity