Severity of nocturnal hypoxia and daytime hypercapnia predicts CPAP failure in patients with COPD and obstructive sleep apnea overlap syndrome

International Consensus Statement on Obstructive Sleep Apnea

BACKGROUND

Evaluation and interpretation of the literature on obstructive sleep apnea (OSA) allows for consolidation and determination of the key factors important for clinical management of the adult OSA patient. Toward this goal, an international collaborative of multidisciplinary experts in sleep apnea evaluation and treatment have produced the International Consensus statement on Obstructive Sleep Apnea (ICS:OSA).

METHODS

Using previously defined methodology, focal topics in OSA were assigned as literature review (LR), evidence-based review (EBR), or evidence-based review with recommendations (EBR-R) formats. Each topic incorporated the available and relevant evidence which was summarized and graded on study quality. Each topic and section underwent iterative review and the ICS:OSA was created and reviewed by all authors for consensus.

RESULTS

The ICS:OSA addresses OSA syndrome definitions, pathophysiology, epidemiology, risk factors for disease, screening methods, diagnostic testing types, multiple treatment modalities, and effects of OSA treatment on multiple OSA-associated comorbidities. Specific focus on outcomes with positive airway pressure (PAP) and surgical treatments were evaluated.

CONCLUSION

This review of the literature consolidates the available knowledge and identifies the limitations of the current evidence on OSA. This effort aims to create a resource for OSA evidence-based practice and identify future research needs. Knowledge gaps and research opportunities include improving the metrics of OSA disease, determining the optimal OSA screening paradigms, developing strategies for PAP adherence and longitudinal care, enhancing selection of PAP alternatives and surgery, understanding health risk outcomes, and translating evidence into individualized approaches to therapy.

A retrospective study of the role of hypercapnia in patients with acromegaly

BACKGROUND

Acromegaly is a multisystemic disease characterized by an excessive release of growth hormone (GH) and insulin-like growth factor-1. Obstructive sleep apnea (OSA) is a common consequence of acromegaly, and hypercapnia is frequently observed in patients with acromegaly, OSA, and obesity. However, the effects of hypercapnia on acromegaly remain unknown. This study was designed to investigate whether there are differences in clinical symptoms, sleep variables, and biochemical remission after surgery for acromegaly in patients with OSA with or without hypercapnia.

METHODS

A retrospective analysis was conducted involving patients with acromegaly and OSA. The pharmacotherapy history for acromegaly before surgery, anthropometric measures, blood gas, sleep monitoring data, and biochemical assays of hypercapnic and eucapnic individuals were collected 1-2 weeks before surgery. Univariate and multivariate logistic regression analyses were performed to determine the risk factors for failed postoperative biochemical remission.

RESULTS

In this study, 94 patients with OSA and acromegaly were included. Among them, 25 (26.6%) had hypercapnia. The hypercapnic group had higher body mass index (92% vs. 62.3%; p = 0.005) and poorer nocturnal hypoxemia index. No serological differences were found between the two groups. According to the post-surgery GH level, 52 patients (55.3%) reached biochemical remission. Univariate logistic regression analysis revealed that diabetes mellitus (odds ratio [OR], 2.59; 95% confidence interval [CI], 1.02-6.55), instead of hypercapnia (OR, 0.61; 95% CI, 0.24-1.58), was associated with lower remission rates. Patients who received pharmacotherapy for acromegaly before surgery (OR, 0.21; 95% CI, 0.06-0.79) and had higher thyroid-stimulating hormone levels (OR, 0.53; 95% CI, 0.32-0.88) were more likely to have biochemical remission after surgery. Multivariate analysis further showed that only diabetes mellitus (OR, 3.29; 95% CI, 1.15-9.46) and preoperative pharmacotherapy (OR, 0.21; 95% CI, 0.06-0.83) remained significant. Hypercapnia, hormone levels, and sleep indicators had no effect on biochemical remission after surgery.

CONCLUSIONS

Single-center evidence shows that hypercapnia alone may not be a risk factor for lower biochemical remission rates. Correcting hypercapnia does not appear to be required before surgery. More evidence is needed to further support this conclusion.

High-Density Lipoproteins: A Role in Inflammation in COPD

Chronic obstructive pulmonary disease (COPD) is a widespread disease associated with high rates of disability and mortality. COPD is characterized by chronic inflammation in the bronchi as well as systemic inflammation, which contributes significantly to the clinically heterogeneous course of the disease. Lipid metabolism disorders are common in COPD, being a part of its pathogenesis. High-density lipoproteins (HDLs) are not only involved in lipid metabolism, but are also part of the organism’s immune and antioxidant defense. In addition, HDL is a versatile transport system for endogenous regulatory agents and is also involved in the removal of exogenous substances such as lipopolysaccharide. These functions, as well as information about lipoprotein metabolism disorders in COPD, allow a broader assessment of their role in the pathogenesis of heterogeneous and comorbid course of the disease.

Review of the prevalence, pathogenesis and management of OSA-COPD overlap

PURPOSE

OSA-COPD overlap is an important and prevalent condition yet remains under-recognised among the vast majority of respiratory health professionals. Patients with OSA-COPD overlap experience more severe respiratory symptoms and worse quality of life, and the relative risk of exacerbations, hospitalisations, and mortality is higher than in either disease state alone.

METHODS

Electronic databases PUBMED and Google Scholar were searched for studies and academic papers that discussed OSA-COPD overlap. Relevant papers that discussed prevalence, pathophysiology, microbiome studies, treatment regimens and outcomes were included in this paper.

RESULTS

High-risk patients with either COPD or OSA should be screened for overlap syndrome as part of routine clinical practice. Screening questionnaires can identify high-risk patients with COPD who may benefit from formal polysomnography. Patients with OSA who are aged over 40 with a significant smoking history or environmental exposures have an increased pre-test probability of obstructive airway disease. The potential roles of gastro-oesophageal reflux disease and lung-gut microbiome are evolving and merit further investigation. A tailored approach to reach a timely diagnosis and thus optimisation of both conditions are key to management. CPAP is the primary therapy for OSA; however, patients with more advanced COPD, with daytime hypercapnia or severe nocturnal desaturations, may benefit from bilevel positive airway pressure.

CONCLUSION

Increased awareness, access to timely investigations and initiation of therapy will improve overall outcomes in OSA-COPD overlap by reducing hospitalisations for exacerbations of COPD and improve mortality rates.

Management of Chronic Respiratory Failure in Chronic Obstructive Pulmonary Disease: High-Intensity and Low-Intensity Ventilation

A significant body of literature supports the benefit of noninvasive ventilation (NIV) for acute hypercapnia in the setting of exacerbations of chronic obstructive pulmonary disease (COPD). In those with severe COPD with chronic hypercapnic respiratory failure, however, the role of NIV has been more controversial. This article reviews the physiologic basis for considering NIV in patients with COPD, summarizes existing evidence supporting the role of NIV in COPD, highlights the patient population and ventilatory approach most likely to offer benefit, and suggests a potential clinical pathway for managing patients.

A novel parameter is better than the AHI to assess nocturnal hypoxaemia and excessive daytime sleepiness in obstructive sleep apnoea

To evaluate whether the percentage of total sleep time spent with apnoea and hypopnoea duration time (AHT%) is better than the apnoea-hypopnoea index (AHI) for the assessment of nocturnal hypoxaemia and excessive daytime sleepiness (EDS) in patients with obstructive sleep apnoea (OSA). Patients with suspected OSA were enrolled. Polysomnography, Epworth Sleepiness Scale, self-administered surveys and anthropometric measures were performed. The efficiency of AHT% and the AHI was evaluated for nocturnal hypoxaemia and EDS. A total of 160 eligible participants were analysed. The median AHT% in normal, mild, moderate and severe OSA patients was significantly different in the four-group patients with OSA. Spearman rank correlations analysis found that the associations were stronger between AHT% with percentage of total sleep time and O₂ saturation of < 90% and minimum nocturnal oxygen saturation than these parameters with the AHI. AHT% had a greater area under the curve than the AHI for predicting EDS in patients with OSA. AHT% was significantly higher in the EDS group. We present a novel parameter, AHT%, to evaluate nocturnal hypoxaemia and EDS in OSA patients. AHT% partially compensates for the shortcomings of the AHI. AHT% is better than the AHI for assessing nocturnal hypoxaemia and EDS. AHT% reflects different clinical characteristics associated with OSA from a new perspective.

Predicting CPAP failure in patients with suspected sleep hypoventilation identified on ambulatory testing

STUDY OBJECTIVES

Home sleep apnea testing (HSAT) is commonly used to diagnose obstructive sleep apnea, but its role in identifying patients with suspected hypoventilation or predicting their response to continuous positive airway pressure (CPAP) therapy has not been assessed. The primary objective was to determine if HSAT, combined with clinical variables, could predict the failure of CPAP to correct nocturnal hypoxemia during polysomnography in a population with suspected hypoventilation. Secondary objectives were to determine if HSAT and clinical parameters could predict awake or sleep hypoventilation.

METHODS

A retrospective review was performed of 142 consecutive patients who underwent split-night polysomnography for suspected hypoventilation after clinical assessment by a sleep physician and review of HSAT. We collected quantitative indices of nocturnal hypoxemia, patient demographics, medications, pulmonary function tests, as well as arterial blood gas data from the night of the polysomnography . CPAP failure was defined as persistent obstructive sleep apnea, hypoxemia (oxygen saturation measured by pulse oximetry < 85%), or hypercapnia despite maximal CPAP.

RESULTS

Failure of CPAP was predicted by awake oxygen saturation and arterial blood gas results but not by HSAT indices of nocturnal hypoxemia. Awake oxygen saturation ≥ 94% ruled out CPAP failure, and partial pressure of oxygen measured by arterial blood gas ≥ 68 mmHg decreased the likelihood of CPAP failure significantly.

CONCLUSIONS

In patients with suspected hypoventilation based on clinical review and HSAT interpretation by a sleep physician, awake oxygen saturation measured by pulse oximetry and partial pressure of oxygen measured by arterial blood gas can reliably identify patients in whom CPAP is likely to fail. Additional research is required to determine the role of HSAT in the identification and treatment of patients with hypoventilation.

Pathogenesis of obstructive sleep apnea in individuals with the COPD + OSA Overlap syndrome versus OSA alone

Overlap syndrome (OVS) is the concurrence of chronic obstructive pulmonary disease (COPD) and obstructive sleep apnea (OSA), and is associated with poor outcomes. We hypothesized that physiological changes in COPD may affect the pathogenesis of OSA in important ways. We therefore sought to measure the anatomical and nonanatomical OSA traits in individuals with OVS and compare to those with OSA alone. Patients with established OVS were recruited, along with age, gender, and BMI matched OSA only controls. Smoking and relevant comorbidities or medications were excluded. Subjects underwent baseline polysomnography followed by an overnight physiological research study to measure the OSA traits (Veupnea , Varousal , Vpassive , Vactive , and loop gain). Fifteen subjects with OVS and 15 matched controls with OSA alone were studied (overall 66 ± 8 years, 20% women, BMI 31 ± 4 kg/m2 , apnea-hypopnea index 49 ± 36/hr). Mixed-modeling was used to incorporate each measurement (range 52-270 measures/trait), and account for age, gender, and BMI. There were no significant differences in the traits between OVS and OSA subjects, although OVS subjects potentially tolerated a lower ventilation before arousal (i.e., harder to wake; p = .06). Worsened lung function was significantly associated with worsened upper airway response and more unstable breathing (p < .05 for all). Consistent differences in key OSA traits were not observed between OVS and OSA alone. However, worse lung function does appear to exert an influence on several OSA traits. These findings indicate that a diagnosis of OVS should not generally influence the approach to OSA, but that lung function might be considered if utilizing OSA trait-specific treatment.

Home mechanical ventilation for chronic obstructive pulmonary disease: What next after the HOT-HMV trial?

The benefits of acute non-invasive ventilation to treat acidotic exacerbations of chronic obstructive pulmonary disease (COPD) are well-established. Until recently, the evidence for home mechanical ventilation (HMV) to treat patients with stable COPD had been lacking. This has subsequently been addressed by the application of higher levels of pressure support combined with targeted management of chronic respiratory failure, which demonstrated a reduction in all-cause mortality. Similarly, the previous trial of home oxygen therapy (HOT) and HMV delivered following an acute exacerbation failed to demonstrate an improvement in outcome. With the focus on patients with persistent hypercapnic respiratory failure in the recovery phase following a life-threatening exacerbation combined with targeted reduction in carbon dioxide, HOT and HMV (HOT-HMV) was shown to be clinically effective in reducing the time to readmission or death and cost effective in both the United Kingdom and United States healthcare systems. Future work will need to focus on promoting adherence to home ventilation and novel auto-titrating ventilator modes to facilitate and optimize the set-up of overnight ventilatory support in different target population such as COPD patients with obstructive sleep apnoea and COPD patients with episodic nocturnal hypoventilation.

Peri-operative treatment of sleep-disordered breathing and outcomes in bariatric patients

Background

Obstructive sleep apnoea (OSA) is increasingly common in bariatric patients undergoing sedation during elective surgery. However, it has not been established how significant a contributor it is to peri-operative respiratory complications and mortality. We sought to pre-operatively identify OSA in bariatric patients and record peri-operative complications during and after bariatric surgery.

Methods

Data were collected and analysed from June 2014 to March 2017 for 410 bariatric surgery patients referred to the sleep laboratory for pre-operative screening and treatment of OSA. The STOP-Bang questionnaire, Epworth Sleepiness Scale (ESS) and nocturnal pulse oximetry were recorded and treatment was allocated with continuous positive airway pressure (CPAP). Peri-operative complications and mortality were the primary outcome measures for patients receiving CPAP treatment for OSA, with patients who did not require CPAP used as control. The mean follow-up time for all patients was 433 and 732 days for the patients who had undergone bariatric surgery. The two groups were compared with Chi square test and unpaired two-tailed t-test.

Results

OSA was present in any form in 70% of the screened patients; 40% of patients involved in the study received CPAP treatment. Patients receiving CPAP treatment [49.5 (11.3) years old, 61% female, 50.3 (8.5) kg/m²] were older, had a lower percentage of females and had a higher body mass index (BMI) than those not receiving CPAP [44.9 (12.0), 81% female, 46.6 (7.7)]. No significant differences were observed between patients on CPAP and those not on CPAP, there was no significant difference in hospital stay or rate of respiratory complications. Out of 53 patients who had undergone bariatric surgery at the cut-off date, only 1 had suffered a respiratory complication.

Conclusions

Bariatric patients who are screened pre-operatively for OSA and treated according to guidelines have no increased risk of respiratory complications compared to patients without OSA.

Practical Recommendations of the Obesity Management Task Force of the European Association for the Study of Obesity for the Post-Bariatric Surgery Medical Management

Bariatric surgery is today the most effective long-term therapy for the management of patients with severe obesity, and its use is recommended by the relevant guidelines of the management of obesity in adults. Bariatric surgery is in general safe and effective, but it can cause new clinical problems and is associated with specific diagnostic, preventive and therapeutic needs. For clinicians, the acquisition of special knowledge and skills is required in order to deliver appropriate and effective care to the post-bariatric patient. In the present recommendations, the basic notions needed to provide first-level adequate medical care to post-bariatric patients are summarised. Basic information about nutrition, management of co-morbidities, pregnancy, psychological issues as well as weight regain prevention and management is derived from current evidences and existing guidelines. A short list of clinical practical recommendations is included for each item. It remains clear that referral to a bariatric multidisciplinary centre, preferably the one performing the original procedure, should be considered in case of more complex clinical situations.