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Objective: To assess whether severe gastroesophageal reflux (GER) is associated with abnormalities in lung function including measures of lung volume and gas diffusion. Methods: Data from 147 patients with obesity (body mass index [BMI] range, 31.7 to 70 kg/m[sup 2]) who presented for obesity surgery was analyzed retrospectively. A questionnaire was completed preoperatively that included a history of GER, frequency and severity of symptoms, investigations, and medications used. A history of lung disease, sleep-disordered breathing, and smoking also was obtained. A physician who was blinded to lung function graded GER severity prospectively by the results of pH monitoring and/or gastroscopy, and medication use. Spirometry, lung volumes, and gas transfer were measured preoperatively. Results: Patients with severe GER had reduced levels of the diffusing capacity of the lung for carbon monoxide (DLCO) [21.1 mL/min/mm Hg; 95% confidence interval (CI), 18.9 to 23.2], as measured by CO transfer, compared with those patients without GER (26.3 mL/min/mm Hg; 95% CI, 24.4 to 28.2; p = 0.001). This remained significant after adjusting for age, gender, BMI, and smoking history. Gas transfer corrected for lung volume also was reduced in the group with severe GER (4.6 mL/min/mm Hg per L; 95% CI, 4.3 to 4.9) compared to the group without GER (5.3 mL/min/mm Hg per L; 95% CI, 5.1 to 5.5; p = 0.001). There was no significant difference in other measures of lung function. Conclusions: Severe GER is associated with an impairment of gas exchange. This may be due to microaspiration of gastric acid or fluid into the airways. [ABSTRACT FROM AUTHOR]

Background: Obstructive sleep apnea (OSA) is common in severely obese subjects (body mass index [BMI] > 35). Overnight polysomnography (OPS) is the "gold standard" method of evaluating this condition; however, it is time-consuming, inconvenient, and expensive. Selection of patients for OPS would be enhanced if we could better predict those likely to have clinically significant OSA. Study objective: To look for clinical and biochemical predictors of OSA in symptomatic patients presenting for obesity surgery. Design and patients: Symptoms suggestive of OSA were sought in a structured interview. We report OPS results of 99 consecutive subjects in whom OSA was clinically suspected. Predictors of apnea-hypopnea index (AHI) were sought from an extensive preoperative data collection. Multivariate linear and logistic analysis was used to identify independent predictors of AHI. Results: Symptoms were poor predictors of AHI, with observed sleep apnea the only positive predictor. Four clinical and two biochemical factors independently predicted AHI: observed sleep apnea, male sex, higher BMI, age, fasting insulin, and glycosylated hemoglobin A[sub Ic] (r² = 0.42). Neck circumference (the best single measure) could replace BMI and sex in the analysis (r² = 0.43). With cutoffs selected, a simple scoring system using these six factors provides a method of predicting those with moderate or severe OSA. A score ≥ 3 provides a sensitivity and specificity of 89% and 81%, and 96% and 71% for AHIs of ≥ 15 and ≥ 30, respectively. None of the 31 subjects with scores of 0 or 1 were found to have an AHI ≥ 15. Conclusion: We explore sleep disturbance and report a simple method of predicting OSA in severely obese symptomatic subjects. This should assist in limiting the use of OPS to those with greater risk and provide a method of assessing risk in those not presenting primarily with a sleep problem. [ABSTRACT FROM AUTHOR]