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

Obstructive Sleep Apnea, Obesity Hypoventilation Syndrome, and Pulmonary Hypertension: A State-of-the-Art Review

The pathophysiological interplay between sleep-disordered breathing (SDB) and pulmonary hypertension (PH) is complex and can involve a variety of mechanisms by which SDB can worsen PH. These mechanistic pathways include wide swings in intrathoracic pressure while breathing against an occluded upper airway, intermittent and/or sustained hypoxemia, acute and/or chronic hypercapnia, and obesity. In this review, we discuss how the downstream consequences of SDB can adversely impact PH, the challenges in accurately diagnosing and classifying PH in the severely obese, and review the limited literature assessing the effect of treating obesity, obstructive sleep apnea, and obesity hypoventilation syndrome on PH.

Hypoxic and Autonomic Mechanisms from Sleep-Disordered Breathing Leading to Cardiopulmonary Dysfunction

Obstructive sleep apnea (OSA) is a common sleep-related breathing disorder. Its prevalence has increased due to increasing obesity and improved screening and diagnostic strategies. OSA overlaps with cardiopulmonary diseases to promote intermittent hypoxia and autonomic dysfunction. Intermittent hypoxia increases the risk for oxidative stress and inflammation, which promotes endothelial dysfunction and predisposes to atherosclerosis and other cardiovascular complications. OSA is associated with an increased sympathetic nervous system drive resulting in autonomic dysfunction leading to worsening of cardiopulmonary diseases. Cardiovascular diseases are observed in 40% to 80% of OSA patients. Therefore, it is essential to screen and treat cardiovascular diseases.

Relationship between obstructive sleep apnea and pulmonary hypertension: past, present and future

INTRODUCTION

Obstructive sleep apnea (OSA) is a widely prevalent condition with consequent multiple organ systems complications. There is consensus that OSA is associated with negative effects on pulmonary hemodynamics but whether it contributes to development of clinical pulmonary hypertension (PH) is unclear.

AREAS COVERED

In this review, we (1) highlight previous studies looking into the possible bidirectional association of OSA and PH, focusing on those that explore clinical prognostic implications, (2) explore potential pathophysiology, (3) discuss the new metrics in OSA, (4) describe endo-phenotyping of OSA, (5) recommend possible risk assessment and screening pathways.

EXPERT OPINION

Relying only on symptoms to consider a sleep study in PH patients is a missed opportunity to detect OSA, which, if present and not treated, can worsen outcomes. The potential prognostic role of sleep study metrics such as oxygen desaturation index (ODI), hypoxic burden (HB) and ventilatory burden (VB) in OSA should be studied in prospective trials to identify patients at risk for PH. AHI alone has not provided clarity. In those with PH, we should consider replacing ambulatory overnight pulse oximetry (OPO) with home sleep studies (HST). In PH patients, mild OSA should be sufficient to consider PAP therapy.

Sleep-disordered breathing patterns and prognosis in pulmonary arterial hypertension: A cluster analysis of nocturnal cardiorespiratory signals

BACKGROUND

Sleep-disordered breathing (SDB) is common among pulmonary arterial hypertension (PAH) patients and has been associated with unfavorable outcomes. This study aims to cluster overnight cardiorespiratory signals to investigate PAH phenotypes and examining their prognostic implications.

METHODS

In this retrospective cohort study, we recruited consecutive PAH patients who underwent right heart catheterization and nocturnal cardiorespiratory polygraphy to evaluate SDB. Cluster analysis was employed to classify patients based on their SDB patterns. Cox regression analysis and Kaplan-Meier curves were utilized to assess the association between cluster membership and clinical outcomes. Logistic regression was used to identify risk factors associated with the cluster at higher risk of adverse outcomes.

RESULTS

The study comprised 386 PAH patients, with a mean age of 44.7 ± 17.0 years, of which 46.6 % were male. Three distinct clusters of PAH patients were identified: Cluster 1 (N = 182) presented with minimal SDB, Cluster 2 (N = 125) displayed obstructive sleep apnea (OSA) without significant hypoxemia, and Cluster 3 (N = 79) exhibited predominantly severe hypoxemic burden along with comorbid OSA. Notably, patients in Cluster 3 had an independent association with an increased risk of clinical worsening (hazard ratio 1.96, 95 % confidence interval [CI] 1.08-3.56, P = 0.027) compared to those in Clusters 1, even after adjusting for common confounders. The rate of clinical worsening for PAH-related events and mortality was higher in Cluster 3 than in Clusters 1 and 2 (26.6 % vs. 12.6 % and 19.2 %, respectively, log-rank P = 0.024). Moreover, the left ventricular mass index was identified as an independent risk factor for Cluster 3 (odds ratios 1.01, 95 % CI 1.00-1.02, P = 0.004).

CONCLUSIONS

Patients with PAH who have nocturnal hypoxemia and OSA had worse clinical outcomes compared to those with only minimal SDB. Tailored management strategies that address both PAH and nocturnal hypoxemia may be effective in improving clinical outcomes.

Sleep-Related Hypoxia, Right Ventricular Dysfunction, and Survival in Patients With Group 1 Pulmonary Arterial Hypertension

BACKGROUND

Group 1 pulmonary arterial hypertension (PAH) is a progressive fatal condition characterized by right ventricular (RV) failure with worse outcomes in connective tissue disease (CTD). Obstructive sleep apnea and sleep-related hypoxia may contribute to RV dysfunction, though the relationship remains unclear.

OBJECTIVES

The aim of this study was to prospectively evaluate the association of the apnea-hypopnea index (AHI) and sleep-related hypoxia with RV function and survival.

METHODS

Pulmonary Vascular Disease Phenomics (National Heart, Lung, and Blood Institute) cohort participants (patients with group 1 PAH, comparators, and healthy control participants) with sleep studies were included. Multimodal RV functional measures were examined in association with AHI and percentage of recording time with oxygen saturation <90% (T90) per 10-unit increment. Linear models, adjusted for demographics, oxygen, diffusing capacity of the lungs for carbon monoxide, pulmonary hypertension medications, assessed AHI and T90, and RV measures. Log-rank test/Cox proportional hazards models adjusted for demographics, oxygen, and positive airway pressure were constructed for transplantation-free survival analyses.

RESULTS

Analysis included 186 participants with group 1 PAH with a mean age of 52.6 ± 14.1 years; 71.5% were women, 80.8% were Caucasian, and there were 43 events (transplantation or death). AHI and T90 were associated with decreased RV ejection fraction (on magnetic resonance imaging), by 2.18% (-2.18; 95% CI: -4.00 to -0.36; P = 0.019) and 0.93% (-0.93; 95% CI: -1.47 to -0.40; P < 0.001), respectively. T90 was associated with increased RV systolic pressure (on echocardiography), by 2.52 mm Hg (2.52; 95% CI: 1.61 to 3.43; P < 0.001); increased mean pulmonary artery pressure (on right heart catheterization), by 0.27 mm Hg (0.27; 95% CI: 0.05 to 0.49; P = 0.019); and RV hypertrophy (on electrocardiography), 1.24 mm (1.24; 95% CI: 1.10 to 1.40; P < 0.001). T90, but not AHI, was associated with a 17% increased 5-year risk for transplantation or death (HR: 1.17; 95% CI: 1.07 to 1.28). In non-CTD-associated PAH, T90 was associated with a 21% increased risk for transplantation or death (HR: 1.21; 95% CI: 1.08 to 1.34). In CTD-associated PAH, T90 was associated with RV dysfunction, but not death or transplantation.

CONCLUSIONS

Sleep-related hypoxia was more strongly associated than AHI with measures of RV dysfunction, death, or transplantation overall and in group 1 non-CTD-associated PAH but only with RV dysfunction in CTD-associated PAH. (Pulmonary Vascular Disease Phenomics Program [PVDOMICS]; NCT02980887).

Intermittent Hypoxemia and Bronchopulmonary Dysplasia with Pulmonary Hypertension in Preterm Infants

Rationale: Bedside biomarkers that allow early identification of infants with bronchopulmonary dysplasia-associated pulmonary hypertension (BPD-PH) are critically important, given the higher risk of death in these infants. Objectives: We hypothesized that infants with BPD-PH have patterns of intermittent hypoxemia (IH) that differ from infants with BPD without PH. Methods: We conducted a matched case-control study of extremely preterm infants from 22 weeks 0 days to 28 weeks 6 days born between 2018 and 2020 at the University of Alabama at Birmingham. BPD-PH status was determined using echocardiographic data performed after postnatal Day 28. Physiologic data were compared between infants with BPD-PH (cases) and BPD alone (control subjects). Receiver operating characteristic (ROC) analysis estimated the predictive ability of cumulative hypoxemia, desaturation frequency, and duration of intermittent hypoxemic events in the week preceding echocardiography to discriminate between cases and control subjects. Measurements and Main Results: Forty infants with BPD-PH were compared with 40 infants with BPD alone. Infants with and without PH had a similar frequency of IH events, but infants with PH had more prolonged hypoxemic events for desaturations below 80% (7 s vs. 6 s; P = 0.03) and 70% (105 s vs. 58 s; P = 0.008). Among infants with BPD-PH, infants who died had longer hypoxemic events below 70% (145 s vs. 72 s; P = 0.01). Using the duration of hypoxemic events below 70%, the areas under the ROC curves for diagnosis of BPD-PH and death in BPD-PH infants were 0.71 and 0.77, respectively. Conclusions: Longer duration of intermittent hypoxemic events was associated both with a diagnosis of BPD-PH and with death among infants with BPD-PH.

Sensitivity to remifentanil and its predictive factor in male patients with moderate to severe obstructive sleep apnea syndrome

OBJECTIVES

Obstructive sleep apnea syndrome (OSAS) is associated with increased risk of postoperative complications, which is possibly related to increased sensitivity to opioid. However, the effect of increased sensitivity to opioids in patients with OSAS remains controversial. This study aims to investigate whether male patients with moderate to severe OSAS have increased sensitivity to opioid remifentanil and its related predictive factors, so as to provide a reference for the rational use of opioids in patients with OSAS.

METHODS

This study was a prospective study. From December 28, 2021 to October 15, 2022, a total of 61 male patients aged 22 to 60 years old, American Society of Anesthesiologists (ASA) status I and II, who underwent nasopharyngeal surgery under general anesthesia, were selected. According to STOP-BANG questionnaire score and apnea-hypopnea index (AHI), the patients were divided into an OSAS group (n=39) and a control group (n=22). The pupil diameter (PD) of the patients was measured by hand-held monocular pupillometer, and the perception threshold (PT) and pain tolerance threshold (PTT) of the patients were measured by somatosensory evoked potential stimulator. The initial PD, PT, and PTT were measured in a quiet environment and recorded as PD0, PT0, and PTT0. Changes in PD, PT, PTT, respiration, and consciousness were recorded after remifentanil infusion. Age, body mass index (BMI), smoking, AHI, minimal oxygen saturation, and percentage of sleep time spent with oxygen saturation <90% (T90) were included as independent variables in multiple linear regression equations to analyze the possible predictors of increased opioid sensitivity in patients with moderate to severe OSAS.

RESULTS

There were no significant differences in PD0, PT0 and PTT0 between the OSAS group and the control group (all P>0.05). After remifentanil infusion, there was no significant difference in the rate of PT change between the 2 groups (P>0.05). The change rate of PTT and PD in the OSAS group was significantly higher than that in the control group (P<0.05 and P<0.001, respectively), PD in the OSAS group was significantly lower than that in the control group (P<0.001). During remifentanil infusion, there were no significant differences in the incidence of respiratory depression and the distribution of observer's assessment of alertness/sedation (OAA/S) scores between the 2 groups (both P>0.05), and there were no changes in mental status and airway support in the patients of the 2 groups. Multiple linear regression showed that T90 was positively correlated with miosis rate (β=0.597, 95% CI 0.269 to 0.924, P<0.05) and the rate of PTT change (β=0.458, 95% CI 0.116 to 0.800, P<0.05). However, minimal oxygen saturation, age, BMI, smoking, and AHI were not correlated with PD change rate and PTT change rate in the OSAS patients (all P>0.05).

CONCLUSIONS

Male patients with moderate to severe OSAS have increased sensitivity to remifentanil, the duration of nocturnal desaturation may be its predictive factor. Male patients with moderate to severe OSAS with a longer duration of nocturnal hypoxia are more sensitive to remifentanil, and the use of opioids in these patients should be more cautious in clinical.

Implication of prolonged nocturnal hypoxemia and obstructive sleep apnea for pulmonary hemodynamics in patients being evaluated for pulmonary hypertension: a retrospective study

STUDY OBJECTIVES

The unique pathophysiologic contributions of obstructive sleep apnea (OSA) toward pulmonary hypertension and right ventricular (RV) dysfunction still represent an understudied area. We aimed to investigate the impacts of various respiratory parameters on pulmonary hemodynamics and RV performance in OSA.

METHODS

Data of consecutive patients with OSA who completed right heart catheterization for evaluation of pulmonary hemodynamics were retrospectively reviewed and analyzed. Univariable and multivariable regression analyses were used to determine the significant respiratory parameter associated with right heart catheterization metrics.

RESULTS

Of 205 patients with OSA (43.4% male), 134 (65.4%) had pulmonary hypertension. Among various sleep parameters, the time percentage spent with SpO2 below 90% (T90) was the sole and the strongest independent factor associated with mean pulmonary artery pressure (mPAP) (β = 0.467, P < .001), pulmonary vascular resistance (PVR) (β = 0.433, P < .001), and RV stroke work index (RVSWI) (β = 0.338, P < .001). For every 5-unit increase in T90, there was approximately 36% greater risk of mPAP ≥ 25 mmHg (odds ratio [OR] 1.36, 95% confidence interval [CI] 1.16-1.59, P < .001), and 45% greater risk of PVR > 3 Woods units (OR 1.45, 95% CI 1.21-1.74, P < .001), respectively. T90 per 5-unit increment was also related to a nearly 1.2-fold higher risk of RVSWI ≥ 12 g/m2/beat (OR 1.19, 95% CI 1.11-1.28, P < .001). These associations remained significant even after multivariable adjustment for confounding factors (all P < .05).

CONCLUSIONS

Increased mPAP, PVR, and RVSWI were associated with prolonged T90 in patients with OSA. Assessment of OSA with insights into hypoxemic duration may aid in early recognition of impaired pulmonary hemodynamics and RV dysfunction.

CITATION

Huang Z, Duan A, Hu M, et al. Implication of prolonged nocturnal hypoxemia and obstructive sleep apnea for pulmonary hemodynamics in patients being evaluated for pulmonary hypertension: a retrospective study. J Clin Sleep Med. 2023;19(2):213-223.

The comorbidity burden and disease phenotype in pre-capillary pulmonary hypertension: The contributing role of obstructive sleep apnea

BACKGROUND

Pre-capillary pulmonary hypertension (PH) with risk factors for left ventricular diastolic dysfunction, described as an atypical phenotype of "mixed" pre- and post-capillary PH, has become a research focus. However, the relationship between obstructive sleep apnea (OSA), a known risk factor for cardiometabolic conditions, and comorbidity burden and disease phenotype in PH remains unclear.

OBJECTIVE

This study aimed to investigate the effect of the presence and severity of OSA on the left ventricular function, comorbidity burden and disease phenotype in pre-capillary PH patients.

METHODS AND RESULTS

We retrospectively examined 450 consecutive pre-capillary PH patients undergoing cardiorespiratory polygraphy and right heart catheterization between May 2020 to November 2021 at Fuwai Hospital. The prevalence of OSA was 34.2%, and the presence and severity of OSA in pre-capillary PH patients was associated with increased left heart mass index (P < 0.001), pulmonary arterial wedge pressure (P = 0.06) and H₂FPEF score (P < 0.001). After adjustment for confounding factors, the severity of OSA measured as apnea-hypopnea index (AHI) was an independent risk factor associated with obesity, systemic hypertension, diabetes mellitus and an atypical phenotype (OR: 1.054, P = 0.004) in pre-capillary PH. A dose-response relationship was also identified between sleep parameters (AHI, oxygen desaturation index, the percentage of sleep time with oxygen saturation<80%) and the number of key comorbidities. Patients with ≥3 comorbidities (atypical phenotype) were older, experienced negative alterations in left ventricular structure and function, and were at a higher risk of OSA.

CONCLUSION

OSA is relatively prevalent in pre-capillary PH patients, independently associated with the presence of a variety of comorbidities and the atypical phenotype of PH. These findings highlight the importance of OSA as a modifiable target for optimal treatment in PH with comorbidities.

Sleep-Disordered Breathing in Adults with Precapillary Pulmonary Hypertension: Prevalence and Predictors of Nocturnal Hypoxemia

PURPOSE

To evaluate the frequency of sleep-disordered breathing (SDB) and predictors of the presence of nocturnal desaturation in adults with pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension.

METHODS

Outpatients with a hemodynamic diagnosis of precapillary pulmonary hypertension who underwent portable polysomnography were evaluated. Diagnosis and severity of SDB were assessed using three well-established respiratory disturbance index (RDI) thresholds: 5.0/h, 15.0/h, and 30.0/h, while nocturnal hypoxemia was defined by the average oxygen saturation (SpO₂) < 90%. Multiple linear regression analysis evaluated the potential relationships among explanatory variables with the dependent variable (average SpO₂ values), with comparisons based on the standardized regression coefficient (β). The R-squared (R²; coefficient of determination) was used to evaluate the goodness-of-fit measure for the linear regression model.

RESULTS

Thirty-six adults were evaluated (69.4% females). The majority of the participants (75.0%) had SDB (26 with obstructive sleep apnea [OSA] and one with central sleep apnea [CSA]); while 50% of them had nocturnal hypoxemia. In the linear regression model (R² = 0.391), the mean pulmonary artery pressure [mPAP] (β - 0.668; p = 0.030) emerged as the only independent parameter of the average SpO₂.

CONCLUSION

Our study found that the majority of the participants had some type of SDB with a marked predominance of OSA over CSA, while half of them had nocturnal desaturation. Neither clinical and hemodynamic parameters nor the RDI was a predictor of nocturnal desaturation, except for mPAP measured during a right heart catheterization, which emerged as the only independent and significant predictor of average SpO₂.

The Cardiovascular and Metabolic Effects of Chronic Hypoxia in Animal Models: A Mini-Review

Animal models are useful to understand the myriad physiological effects of hypoxia. Such models attempt to recapitulate the hypoxemia of human disease in various ways. In this mini-review, we consider the various animal models which have been deployed to understand the effects of chronic hypoxia on pulmonary and systemic blood pressure, glucose and lipid metabolism, atherosclerosis, and stroke. Chronic sustained hypoxia (CSH)-a model of chronic lung or heart diseases in which hypoxemia may be longstanding and persistent, or of high altitude, in which effective atmospheric oxygen concentration is low-reliably induces pulmonary hypertension in rodents, and appears to have protective effects on glucose metabolism. Chronic intermittent hypoxia (CIH) has long been used as a model of obstructive sleep apnea (OSA), in which recurrent airway occlusion results in intermittent reductions in oxyhemoglobin saturations throughout the night. CIH was first shown to increase systemic blood pressure, but has also been associated with other maladaptive physiological changes, including glucose dysregulation, atherosclerosis, progression of nonalcoholic fatty liver disease, and endothelial dysfunction. However, models of CIH have generally been implemented so as to mimic severe human OSA, with comparatively less focus on milder hypoxic regimens. Here we discuss CSH and CIH conceptually, the effects of these stimuli, and limitations of the available data.

Negative impact of the hypopnea index or duration increase after a non-frame work surgery in patients with very severe obstructive sleep apnea

A non-framework surgery could change the postoperative components of breathing disturbances and increase the frequency or duration of hypopnea in patients with very severe obstructive sleep apnea (OSA). Either an increase of hypopnea index, which increases apnea–hypopnea index (AHI), or an increase of its duration raises the concern of worsening the oxygen desaturation and so morbidity and mortality associated with OSA. It is unclear how the oxygen saturation would change in those having increased frequency or duration of hypopneas after the surgery. Here in 17 patients with AHI ≥ 60 events/h, having increased frequency or duration of hypopneas after the non-framework surgery, the results show that the surgery improved oxygen saturation by reducing obstructive-apnea index (36.1 events/h) and duration (8.6 s/event), despite it increased hypopnea index (16.8 events/h) and duration (9.8 s/event). The surgery improved the average of the mean oxyhemoglobin saturation of pulse oximetry (SpO2) by 2.8% (toward a ceiling mean of 94.3%), mean minimal SpO2 by 7.5%, and mean desaturation by 5%. The results suggest sufficient apnea reduction and shift from apnea to hypopnea may mask the negative impact of the increase of hypopnea index or duration and improve postoperative mean SpO2, minimal SpO2, and mean desaturation.

Sleep apnea and pulmonary hypertension: A riddle waiting to be solved

Obstructive sleep apnea (OSA) is an under-recognized yet highly prevalent disease that has major implications to cardiovascular health. Pulmonary hypertension (pH) is less common but none the less a fatal condition. The association of OSA and PH is a known but not well understood phenomenon. Furthermore, the relationship appears to be bi-directional with limited understanding of the mechanism(s) driving the processes. PH in OSA has real time consequences as it has been shown to increase mortality. Limited data suggests that treatment with continuous positive pressure therapy may be beneficial and reduce pulmonary pressure. In this review, we discuss current data on prevalence of PH in OSA and vice versa. We also explore the pathophysiology of this relationship and a proposed mechanism for their connection. Finally, we address the treatment of OSA with CPAP and its impact on pulmonary pressures. Gaps in knowledge and future research potential are illustrated and discoursed.

Obstructive sleep apnea and pulmonary hypertension: a bidirectional relationship

Mesarwi O, Malhotra A. Obstructive sleep apnea and pulmonary hypertension: a bidirectional relationship. J Clin Sleep Med . 2020;16(8):1223–1224.