Predictors of obstructive sleep apnea in lung transplant recipients

The Association between Idiopathic Pulmonary Fibrosis and Obstructive Sleep Apnea: A Systematic Review and Meta-Analysis

The prevalence of obstructive sleep apnea (OSA) has greatly increased in recent years. Recent data suggest that severe and moderate forms of OSA affect between 6 and 17% of adults in the general population. Many papers are reporting the significantly increased prevalence of OSA in patients suffering from fibrotic diseases, including idiopathic pulmonary fibrosis (IPF). Therefore, we performed a systematic review and meta-analysis regarding the dependency between IPF and OSA. Due to the lack of papers focusing on IPF among OSA patients, we focused on the prevalence of OSA among IPF patients. In the search strategy, a total of 684 abstracts were identified, 496 after the removal of duplicates. After the screening of titles and abstracts, 31 studies were qualified for further full-text analysis for eligibility criteria. The final analysis was performed on 614 IPF patients from 18 studies, which met inclusion criteria. There were 469 (76.38%) IPF patients with OSA and 145 (23.62%) without. The mean age varied from 60.9 ± 8.1 up to 70.3 ± 7.9. The obtained prevalence was 76.4 (95% CI: 72.9–79.7) and 75.7 (95% CI: 70.1–80.9) for fixed and random effects, respectively. The median prevalence of OSA among non-IPF patients for all the ethnics groups included in this study was 16,4% (IQR: 3.4%–26.8%). The study provides strong evidence for the increased prevalence of OSA in IPF patients when comparing with the general OSA prevalence.

A Scoping Review of the Literature on Sleep Quality in Adult Lung Transplant Recipients

Introduction: Lung transplant recipients face challenging postoperative complications and are at risk for poor sleep quality. Sleep quality, as a complex clinical phenomenon, has multiple subjective and objective connotations. Measures and definitions of sleep quality are not standardized. Objective: A scoping review methodology was used to systematically map the relevant literature, provide an overview of available sleep quality measures, and to identify knowledge gaps. Methods: A systematic search of published and gray literature enabled knowledge synthesis of the last 10 years of evidence documenting sleep quality in lung transplant recipients. The search revealed 246 articles with only 12 sources meeting the eligibility criteria. Results: Sources varied in terms of definitions and measures of sleep quality. Subjective, objective, or a combination of both measures were used across the relevant literature with findings confirming that poor sleep quality was common in lung transplant recipients. Significant associations with poor sleep quality included younger age, female gender, exposure to tacrolimus, anxiety, and depression. Discussion: Systematic literature assessing sleep quality in lung transplant recipients is sparse and lacks conceptual and operational definitions. Future research can focus on designing prospective observational studies. Subjective and objective measures for sleep quality need to be validated in lung transplant recipients. Further rigorous research is needed to standardize measures of sleep quality and to further examine potential risk factors that affect sleep after lung transplantation.

Sleep-disordered breathing after lung transplantation: An observational cohort study

Data concerning sleep-disordered breathing (SDB) after lung transplantation (LTX) are scarce. This study aims to analyze prevalence, associated factors, and impact on survival of moderate to severe SDB in a large cohort of consecutive LTX patients (n = 219). Patients underwent a diagnostic polysomnography 1 year after LTX. Moderate to severe SDB was present in 57.5% of patients, with the highest prevalence in chronic obstructive pulmonary disease/emphysema (71.1%) and pulmonary fibrosis (65.1%). SDB patients were older, mostly male, and had higher body mass index and neck circumference. Nocturnal diastolic and 24-hour blood pressures were higher in SDB patients. In 45 patients, polysomnography was also performed pre-LTX. Compared to pre-LTX, mean apnea/hypopnea index (AHI) increased significantly after LTX. A significant correlation was seen between lung function parameters and AHI, suggesting a role of decreased caudal traction on the pharynx. Presence of SDB had no impact on mortality or prevalence of chronic lung allograft dysfunction. However, survival was better in continuous positive airway pressure (CPAP) compliant SDB patients compared to SDB patients without CPAP treatment. These findings may be pertinent for systematic screening of SDB after LTX.

Sleep quality and its association with health-related quality of life of patients on lung transplantation waitlist in Japan

PURPOSE

Poor quality of sleep is a common feature in patients with various lung diseases and affects their health-related quality of life (HRQL). We evaluated sleep quality and HRQL in patients on the waitlist for lung transplantation in Japan.

METHODS

In this prospective study, patient-reported and physiological data were collected from patients newly registered on the waitlist for lung transplantation in Japan. Sleep quality was evaluated using the Pittsburgh Sleep Quality Index (PSQI) and HRQL using the St. George's Respiratory Questionnaire (SGRQ). The frequency of poor sleep quality, correlations between sleep quality and various clinical parameters, and predictive factors of sleep quality were examined.

RESULTS

Of 193 patients, the three most-frequent indications for lung transplantation were interstitial pneumonia (n = 96), pulmonary complications of hematopoietic stem cell transplantation (n = 25), and pulmonary hypertension (n = 17). Poor sleep quality (PSQI > 5) was observed in 102 patients (53%) and was significantly associated with worse Hospital Anxiety and Depression Score (HADS), worse SGRQ score, worse modified Medical Research Council Dyspnea score, and shorter 6-min walk distance. However, it was not associated with sex, pulmonary function, interstitial pneumonia, or arterial blood gas. Stepwise multiple regression analysis indicated that poor sleep quality was explained significantly by HADS anxiety (23%) and SGRQ Symptoms (10%).

CONCLUSION

Poor sleep quality was found to be common among patients on the lung transplantation waitlist in Japan. The two most significant factors responsible for impaired sleep quality were anxiety and respiratory symptoms. Additional care should be taken to ensuring a better quality of sleep for such patients.

Obstructive Sleep Apnea in Patients With Fibrotic Interstitial Lung Disease and COPD

STUDY OBJECTIVES

Despite the clinical and prognostic significance of obstructive sleep apnea (OSA) in chronic respiratory diseases (CRDs), there have been few studies about the possible predictors of OSA and the effect of OSA on quality of life in patients with CRDs. The objectives were to identify physiological and clinical parameters that predict the occurrence and severity of OSA and to investigate the effect of OSA on quality of life in patients with CRDs.

METHODS

Seventy-three patients with chronic obstructive pulmonary disease (COPD) and 77 patients with fibrotic interstitial lung disease (ILD) underwent overnight polysomnography (PSG) and pulmonary function testing and completed clinical questionnaires. The oximetry tracing was interpreted blindly with respect to the PSG results.

RESULTS

The prevalence of OSA was 44% and 62% in COPD and ILD, respectively. The COPD assessment test item scores related to sleep quality and daily vitality were worse among patients with OSA than among patients without OSA. The STOP-BANG questionnaire (cutoff point ≥ 3) and oxygen desaturation index from the oximetry recording (oxygen desaturation index (ODI) were associated with OSA in CRDs. The STOP-BANG questionnaire with a cutoff point ≥ 3 or 6 had the highest sensitivity and specificity, respectively, in detecting OSA in CRDs. ODI had the best accuracy in identifying OSA and was independently associated with the apnea-hypopnea index in CRDs.

CONCLUSIONS

We found OSA to be common and associated with worse sleep quality and less daily vitality in patients with advanced CRDs. The STOP-BANG questionnaire with different cutoff points may help rule in or rule out OSA. Overnight oximetry can be used as a screening tool for OSA and can assist the clinical evaluation of OSA in patients with CRDs.

Non-respiratory complaints are main reasons for disturbed sleep post lung transplant

BACKGROUND

Poor sleep is prevalent in lung transplant recipients and affects quality of life negatively. To improve quality of sleep, it's important to identify the causes of poor sleep. We conducted a survey to identify the reasons for poor sleep quality in the recipients.

METHODS

We surveyed lung transplant recipients (2003-2010) at Baylor College of Medicine/The Methodist Hospital lung transplant center. We used a compilation of questionnaires, including the Pittsburgh Sleep Quality Index (PSQI), Berlin Questionnaire, Epworth Sleepiness Scale (ESS) and Short Form 36 (SF36). Descriptive analysis was performed on the responses.

RESULTS

Of the 167 participants, 54 responded (32.3%) with mean age 60.6 years (SD 9.8), 48% male, and a mean post-transplant body mass index (BMI) of 27 (SD 4.7). The responders reported a long mean sleep latency of 33.2 min (SD 32.5), poor sleep quality (74% with PSQI score > 5), excessive daytime sleepiness (ESS > 9 in 29%), poor physical QOL with SF36 mean score of 41.3 (SD 9.4), and high risk for OSA (48.2%). About 30% and 72% reported sleep initiation and maintenance insomnia, respectively. The poor sleep quality was due to "getup to go to bathroom" (85%), "cough or snore loudly" (33%), "have pain" (27.8%), and "feel too cold" (27.8%). Furthermore, 5% reported "Can't breathe comfortably" as reason for poor sleep.

CONCLUSIONS

The recipients reported poor sleep and quality of life. The non-respiratory complaints were important factors for poor sleep. Attention to these factors may help to outline better management strategies to improve sleep in lung transplant recipients.

Decreased Hypercapnic Ventilatory Response in Long-Term Lung Transplant Recipients is Associated with Exercise Impairment

PURPOSE

Bilateral lung transplantation results in complete denervation of the lung and might impair hypercapnic ventilatory response (HCVR). However, experimental and clinical findings are scarce and conflicting. Therefore, this study investigated the relationship between HCVR and exercise capacity after long-term bilateral lung transplantation.

METHODS

This cross-sectional analysis enrolled 46 bilateral lung transplant recipients between October 2011 and July 2012 who underwent cardiopulmonary exercise testing to evaluate maximum workload, and carbon dioxide (CO2) rebreathing. CO2 rebreathing was also evaluated in 35 control subjects.

RESULTS

In lung transplant recipients age was 54 ± 11 years, body mass index (BMI) 25.4 ± 4.1 kg/m(2), and time after transplantation 4.5 ± 2.5 years (range 9 months to 10 years). Controls were aged 41 ± 12 years and had a BMI of 24.9 ± 4.0 kg/m(2). There were significant differences between lung transplant recipients and controls in forced expiratory volume in 1 s (76 ± 22 vs. 94 ± 12 % predicted, p < 0.001) and inspiratory vital capacity (91 ± 20 vs. 105 ± 14 % predicted, p = 0.001). Blood gases did not differ significantly in patients versus controls. HCVR in lung transplant recipients was 1.44 ± 1.07 L/min/mmHg compared with 2.09 ± 1.14 L/min/mmHg in controls (p = 0.001). Exercise capacity in lung transplant recipients (73 ± 24 W) was 49 % predicted. Linear regression analysis showed that exercise capacity was significantly associated with HCVR. A 1 L/min/mmHg decrease in HCVR decreased exercise capacity by 50 W.

CONCLUSION

HCVR is reduced in long-term bilateral lung transplant recipients and this might explain the observed impairment of exercise capacity.