Prevalence of sleep apnea and electrocardiographic disturbances in morbidly obese patients

Objective: To determine the prevalence of sleep apnea in morbidly obese pat ients and its relationship with cardiac arrhythmias. Research Methods and Procedures: Fifty-two consecutive morbidly obese (body mass index greater than or equal to 40 kg/m(2)) outpatients from the Obesi ty Clinic of the National Institute of Nutrition Salvador Zubiran underwent two nights of polysomnography with standard laboratory techniques. Electro cardiographic polysomnography signals (Lead II) were evaluated by two exper ienced cardiologists, and sleep complaints were measured with a standard sl eep questionnaire (Sleep Disorders Questionnaire). In order to make compari sons between groups with different severities of sleep-disordered breathing , we classified the patients in four groups using the apnea-hypopnea index (AHI): Group 1, AHI 5 < 15 (n = 10); Group 2, AHI 15 < 30 (n = 10); Group 3 , AHI 30 < 65 (n = 14); Group 4, AHI greater than or equal to 65 (n = 17). Results: A wide range of sleep-disordered breathing, ranging from AHI of 2. 5 to 128.9 was found. Ninety-eight percent of the sample (n = 51) had an AH I greater than or equal to 5 (mean = 51 +/- 37), and 33% had severe sleep a pnea with AHI greater than or equal to 65 with a mean nocturnal desaturatio n time of <65% over 135 minutes. Electrocardiographic abnormalities were pr esent in 31% of the patients. Cardiac rhythm alterations showed an associat ion with the level of sleep-disordered breathing and oxygen desaturation. Discussion: We conclude that there is a high prevalence of sleep apnea in m orbidly obese patients and that the risk for cardiac arrhythmias increases in this population in the presence of a severe sleep apnea (AHI greater tha n or equal to 65) with severe oxygen desaturation (Sao(2) less than or equa l to 65%).