Pulmonary artery hemodynamics are associated with duration of nocturnal desaturation but not apnea-hypopnea index.

STUDY OBJECTIVES: Sleep-disordered breathing (SDB) and nocturnal hypoxia are prevalent among patients with precapillary pulmonary hypertension (PAH). The rationale for these associations remains unclear and these relationships have not been well studied in other forms of pulmonary hypertension (PH). We hypothesized that severity of SDB and nocturnal hypoxia are associated with worsening pulmonary hemodynamics, regardless of hemodynamic profile. METHODS: 493 Patients were divided into 4 groups: 1) no PH, 2) postcapillary pulmonary hypertension (PVH), 3) PAH, and 4) mixed PAH/PVH. The relationship between RHC measurements and apnea-hypopnea index (AHI) or the percentage of sleep time spent with oxygen saturation <90% (T90) was calculated using multiple linear regression. ANOVA was used for between-group comparisons. Statistical models were adjusted for known confounders. RESULTS: AHI did not differ between hemodynamic subgroups (p=0.27) and was not associated with right atrial pressure (RAP) (0.11 +/- 0.19, p=0.55), Cardiac index (CI) (0.25 +/- 1.64, p=0.88)), mean pulmonary artery pressure (mPAP) (-0.004 +/- 0.09, p=0.97) or pulmonary artery occlusion pressure (PAOP) (0.16 +/- 0.14, p=0.26). While patients with PH had a higher T90 than those without (mean 24.2% vs. 11.7%, p<0.001), there was no difference in T90 between individual PH subgroups (p=0.70). T90 was associated with mPAP (0.55 +/- 0.10, p<0.0001), PVR (1.61 +/- 0.49, p=0.001) and RAP (0.50 +/- 0.20, p=0.01), but not CI (-0.76 +/- 1.73, p=0.66) or PAOP (0.23 +/- 0.15, p=0.13). CONCLUSIONS: Increased PH severity was associated with longer duration of nocturnal hypoxia regardless of hemodynamic subgroup.