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

STUDY OBJECTIVES: Sleep-disordered breathing 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 sleep-disordered breathing and nocturnal hypoxia are associated with worsening pulmonary hemodynamics, regardless of hemodynamic profile. METHODS: Four hundred ninety-three patients were divided into 4 groups: 1) no PH, 2) postcapillary pulmonary hypertension, 3) PAH, and 4) mixed PAH/postcapillary pulmonary hypertension. The relationship between right heart catheterization measurements and apnea-hypopnea index or the percentage of sleep time spent with oxygen saturation < 90% (T90) was calculated using multiple linear regression. Analysis of variance was used for between-group comparisons. Statistical models were adjusted for known confounders. RESULTS: Apnea-hypopnea index did not differ between hemodynamic subgroups (P = .27) and was not associated with right atrial pressure (.11 ± .19, P = .55), cardiac index (.25 ± 1.64, P = .88), mean pulmonary artery pressure (-.004 ± .09, P = .97), or pulmonary artery occlusion pressure (.16 ± .14, P = .26). While patients with PH had a higher T90 than those without (mean 24.2% vs 11.7%, P < .001), there was no difference in T90 between individual PH subgroups (P = .70). T90 was associated with mean pulmonary artery pressure (.55 ± .10, P < .0001), PVR (1.61 ± .49, P = .001), and right atrial pressure (.50 ± .20, P = .01), but not cardiac index (-.76 ± 1.73, P = .66), or pulmonary artery occlusion pressure (.23 ± .15, P = .13). CONCLUSIONS: Increased PH severity was associated with longer duration of nocturnal hypoxia regardless of hemodynamic subgroup.

Effect of Continuous Positive Airway Pressure on Cardiovascular Biomarkers: The Sleep Apnea Stress Randomized Controlled Trial.

BACKGROUND: Although existing research highlights the relationship of OSA and cardiovascular disease, the effect of OSA treatment on cardiovascular biomarkers remains unclear. We evaluated the effect of OSA treatment on oxidative stress/inflammation measures. METHODS: We conducted a parallel, randomized controlled trial in moderate to severe OSA (apnea-hypopnea index ≥ 15) patients to examine effects of 2-month CPAP vs sham-CPAP on the primary outcome of oxidative stress/inflammation (F2-isoprostanes: ng/mg) and myeloperoxidase: pmol/L) and secondary oxidative stress measures. Exploratory secondary analyses included vascular and systemic inflammation markers. Linear models adjusted for baseline values examined effect of CPAP on biomarker change (least squares means, 95% CI) including secondary stratified analyses examining CPAP adherence and degree of hypoxia. RESULTS: Of 153 participants, 76 were randomized to CPAP and 77 to sham-CPAP. In an intent-to-treat analyses, no significant change was observed in the sham and CPAP groups respectively: F2-isoprostanes (-0.02 [-0.12 to 0.10] vs -0.08 [-0.18 to 0.03]) or myeloperoxidase (-3.33 [-17.02 to 10.37] vs -5.15 [-18.65 to 8.35]), nor other oxidative markers; findings that persisted in analyses stratified by adherence and hypoxia. Exploratory analyses revealed percentage reduction of soluble IL-6 receptor (ng/mL) levels (-0.04 [-0.08 to -0.01] vs 0.02 [-0.02 to 0.06], P = .019) and augmentation index (%) (-6.49 [-9.32 to -3.65] vs 0.44 [-2.22 to 3.10], P < .001) with CPAP compared with sham, respectively. CONCLUSIONS: In moderate to severe OSA, 2-month CPAP vs sham did not reduce oxidative stress despite consideration of a broad range of measures, positive airway pressure adherence, and hypoxia burden. These findings suggest that nonoxidative stress pathways primarily modulate OSA-related cardiovascular consequences. TRIAL REGISTRATION: ClinicalTrials.govNCT00607893.

Postoperative Complications in Patients With Unrecognized Obesity Hypoventilation Syndrome Undergoing Elective Noncardiac Surgery.

BACKGROUND: Among patients with OSA, a higher number of medical morbidities are known to be associated with those who have obesity hypoventilation syndrome (OHS) compared with OSA alone. OHS can pose a higher risk of postoperative complications after elective noncardiac surgery (NCS) and often is unrecognized at the time of surgery. The objective of this study was to retrospectively identify patients with OHS and compare their postoperative outcomes with those of patients with OSA alone. METHODS: Patients meeting criteria for OHS were identified within a large cohort with OSA who underwent elective NCS at a major tertiary care center. We identified postoperative outcomes associated with OSA and OHS as well as the clinical determinants of OHS (BMI, apnea-hypopnea index [AHI]). Multivariable logistic and linear regression models were used for dichotomous and continuous outcomes, respectively. RESULTS: Patients with hypercapnia from definite or possible OHS and overlap syndrome are more likely to experience postoperative respiratory failure (OR, 10.9; 95% CI, 3.7-32.3; P < .0001), postoperative heart failure (OR, 5.4; 95% CI, 1.9-15.7; P = .002), prolonged intubation (OR, 3.1; 95% CI, 0.6-15.3; P = .2), postoperative ICU transfer (OR, 10.9; 95% CI, 3.7-32.3; P < .0001), and longer ICU (?-coefficient, 0.86; SE, 0.32; P = .009) and hospital (?-coefficient, 2.94; SE, 0.87; P = .0008) lengths of stay compared with patients with OSA. Among the clinical determinants of OHS, neither BMI nor AHI showed associations with any postoperative outcomes in univariable or multivariable regression. CONCLUSIONS: Better emphasis is needed on preoperative recognition of hypercapnia among patients with OSA or overlap syndrome undergoing elective NCS.