Analysis of oxygen desaturation variables and correlations with apnea –hypopnea index and systemic hypertension (SH).
817 consecutive patients with suspected obstructive sleep apnea were evaluated with sleep questionnaires, anthropometric measurements, polisomnography for AHI (apnea-hypopnea index normal 0–4, mild 5–14, and moderate 15–29, severe over 30). We measured the Odds Ratio (OR) together with 95% confidence interval (CI) in a univariate analysis and the independent variables were used in order to identify the most important predictors. Multiple linear regression analysis was performed.
748 (91,55%) patients had OSA, 541 males (72,47%), 208 females (27,53%), age 52 ±11,89 years (16–84), AHI 34,10/h ± 27,41, 65,61% with systemic hypertension (SHT), 16,18% with COPD, lowest desaturation (LD) 70,49 ± 16,39 % (23–93), desaturation index (DI) 30,64 ± 24,30/h (6–128), medium desaturation (MD) 91,98 ±4,01%. The DI is not linear correlated with AHI and in multivariate analysis is an independent factor for OSA (OR 3, 11, p< 0,001, 95% confidence interval 2, 67–4, 59). In multiple linear regression analysis the relationship between AHI and the DI is direct proportional and the correlation is powerful, r = 0, 7465, p <0,001. DI was significantly higher with SHT (31, 12/h vs. 20, 21/h, p < 0,001) and COPD (36, 24/h vs. 24, 6/h, p = 0,004). The relationship between the AHI and MD is inversely proportional, r = 0, 30, p<0,001 and values are significantly different in SHT (90, 6% vs. 92, 93%, p < 0.001) and COPD (89, 87% vs. 91, 89%, p < 0.001). LD is an independent factor for SHT (OR 3,78, p < 0,001, 95% confidence interval 2,89–4,87).
The desaturation index, medium desaturation and lowest desaturation are significantly lower at patients with OSA and co morbidities (systemic hypertension, COPD). The lowest desaturation is an independent predictor for systemic hypertension.
The patho-physiological hallmark of obstructive sleep apnea is nocturnal intermittent hypoxia, with cardiovascular consequences, the most frequent systemic hypertension.
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