Hypoxemia associated with OSAHS adversely affects the cardiovascular system and intellectual function. Defining and ameliorating the factors that may increase the severity of hypoxemia may be beneficial adjunctive measures to CPAP therapy. In OSAHS, the factors affecting nocturnal oxygen desaturation (NOD) are yet to be defined.We hypothesized that active cigarette smoking or a high BMI increases the severity of NOD in patients with OSAHS.
The 366 patients referred to the sleep lab from 1/02 - 01/04 were studied. The severity of NOD was measured as the percentage of the total sleep time (TST) spent with oxygen saturation below 90%(%TST<90%). An AHI of ≥ 10 was used to diagnose OSAHS. All patients had an oxygen saturation of > 94% before Polysomnography.
Nonparametric tests showed a statistically significant difference in NOD between apneics, nonapneics (P < 0.01); Obese with a BMI >35 kg/m2(obese35), obese with a BMI < 35 kg/m2 (nonobese35) (P <0.01) and active smokers, non-active smokers (P=0.002). Patients with COPD and/or CHF didn’t differ significantly from those without these conditions (P=0.069). Age and NOD were not significantly correlated (P=0.140) ANOVA showed statistically significant difference in NOD between apneics, nonapneics; obese35, nonobese35; active smokers, non-active smokers and apneics-nonobese35 versus apneics-obese35 (P= <0.01, <0.01, 0.018 and 0.015) respectively. The mean and 95% CI of (%TST<90%) in nonapneics-obese35 argue against the effect of obesity35 on NOD being merely secondary to Obesity Hypoventilation Syndrome. The correlation between the severity of NOD and BMI > 35 kg/m2 was statistically significant (P <0.01).
Both a BMI > 35 kg/m2 and active cigarette smoking increase the severity of NOD regardless of coexisting OSAHS. When combined with OSAHS, a BMI > 35 kg/m2 has a synergistic effect on the severity of NOD. The severity of NOD increases as the BMI increases above 35 kg/m2.
Actively smoking, high BMI patients with suspicion of OSAHS are at higher risk for hypoxemia and may be considered for scheduling priority and closer monitoring of CPAP therapy thereafter.
Descriptive statisticsN.%Total population366100Males19052Females17648Active smokers11431Non-active smokers25269OSAHS22561No OSAHS14139COPD and/or CHF13437No COPD and/or CHF23263
ANOVA resultsMeanP-valueStd. Error95% CILower BoundUpper BoundOSAHS−84.01<0.013.1977.7390.29+46.532.3241.9651.10Obese35−73.83<0.012.9468.0379.63+56.712.6251.5461.877Active smoker−69.950.0182.0865.8674.05+60.583.3553.9867.18OSAHS+59.920.0153.7052.6367.21Obese35−OSAHS+33.142.8027.6238.65Obese35+OSAHS−80.274.4471.5489.02Obese35+
H.F. Ghali-Hana, None.