Abnormal Activity of Neck Inspiratory Muscles during Sleep as a Prognostic Indicator in Chronic Obstructive Pulmonary Disease

Paradoxical breathing during sleep is associated with increased sleep apnea and reduced ventilatory capacities in high-level spinal cord injury

Sleep-disordered breathing is highly prevalent in individuals with high-level spinal cord injury. In addition, chest mechanics are known to be altered, leading to paradoxical breathing. Here we investigated the interaction between paradoxical breathing and sleep quality in these patients, and its association with measurements of respiratory function, hypercapnic ventilatory response and peak exercise ventilation. Home-based polysomnography was performed in 13 patients with spinal cord injury (C4 to T4) untreated for sleep-disordered breathing. We defined paradoxical breathing as counterphase between thoracic and abdominal movements during slow-wave and rapid eye movement sleep. Sleep quality, pulmonary function, hypercapnic ventilatory responses and peak exercise ventilation were compared between those with and without paradoxical breathing. Half of individuals presented with nocturnal paradoxical breathing. Despite similar age, body mass index, injury level, time since injury, and respiratory function, those with paradoxical breathing had higher apnea-hypopnea index (13 ± 8 versus 5 ± 3 events per hr) and average sleep heart rate (67 ± 12 versus 54 ± 4 bpm; p < 0.05). Moreover, paradoxical breathing was associated with lower hypercapnic ventilatory response (slope: 0.35 ± 0.17 versus 0.96 ± 0.38) and lower peak exercise ventilation (33 ± 4 versus 48 ± 12 L min-1; p < 0.05). Nocturnal respiratory muscle desynchronization could play a role in the pathophysiology of sleep apnea, and could relate to low ventilatory responses to both hypercapnia and exercise in high-level spinal cord injury. Polysomnography may be an important diagnostic tool for these patients for whom therapeutic approaches should be considered to treat this abnormality.

Dietary Beetroot Juice - Effects in Patients with COPD: A Review

Chronic Obstructive Pulmonary Disease (COPD) exerts a severe toll on human health and the economy, with high prevalence and mortality rates. The search for bioactive components effective in the treatment of COPD has become a focal point of research. Beetroot juice, readily accessible and cost-effective, is noted for its ability to enhance athletic performance and for its preventive and therapeutic impact on hypertension. Beetroot juice is a rich source of dietary nitrates and modulates physiological processes via the nitrate-nitrite- nitric oxide pathway, exerting multiple beneficial effects such as antihypertensive, bronchodilatory, anti-inflammatory, antioxidant, hypoglycemic, and lipid-lowering actions. This paper provides a review of the existing research on the effects of beetroot juice on COPD, summarizing its potential in enhancing exercise capacity, lowering blood pressure, improving vascular function, and ameliorating sleep quality among patients with COPD. The review serves as a reference for the prospective use of beetroot juice in the symptomatic improvement of COPD, as well as in the prevention of exacerbations and associated comorbidities.

Clinical correlates of respiratory disorders in patients with severe multiple sclerosis: A cross-sectional cohort

BACKGROUND

Respiratory disorders remain incompletely described in multiple sclerosis (MS), even though they are a frequent cause of death.

METHODS

The objective was to describe respiratory disorders in MS patients with Expanded Disability Status Score (EDSS) ⩾ 6.5. Diaphragm dysfunction was defined by at least two of the seven criteria: clinical signs, inspiratory recruitment of neck muscles during wakefulness, reduced upright vital capacity (VC) < 80%, upright-to-supine VC ⩾ 15% of upright VC, decrease in Maximal Inspiratory Pressure < 60%, phasic activation of inspiratory neck muscles during sleep, and opposition of thoracic and abdominal movements during sleep. Cough weakness was defined by a peak cough flow < 270 L/min and/or need for cough assist. Sleep apnea syndrome was defined by an apnea-hypopnea index ⩾ 15.

RESULTS

Notably, 71 MS patients were included: median age 54 [48, 61] years; median disease duration 21.4 [16.0, 31.4] years. Of these, 52 patients had one or more respiratory disorders; diaphragm dysfunction was the most frequent (n = 34). Patients with diaphragm dysfunction and cough weakness were more disabled. The fatigue score and the cognitive evaluations did not differ between the groups. Five patients required non-invasive ventilation.

CONCLUSION

Respiratory disorders are frequent in severe MS, mostly diaphragm dysfunction. Of interest, instrumental interventions are available to address these disorders.

[Take-home messages from the 2nd COPD 2023 Biennial of the French Society of Respiratory Diseases. Placing the patient at the center of the care pathway]

INTRODUCTION

The second COPD Biennial organized by the COPD working group of the French Society of Respiratory Diseases took place in Paris (Cochin) on 13th December 2023.

STATE OF THE ART

Major trends in 2023 were discussed; they encompassed concepts, definitions, biologics, care pathways, pulmonary rehabilitation and complex situations entailed by respiratory infections, cardiovascular comorbidities and pulmonary hypertension, and modalities of oxygen therapy and ventilation.

PERSPECTIVES

The different talks underlined major changes in COPD including the concepts of pre-COPD, etiotypes, health trajectories and new definitions of exacerbation. Recent results in biologics for COPD open the door to new pharmacological options. Assessment of current care pathways in France highlighted some causes for concern. For example, pulmonary rehabilitation is a key but insufficiently practiced element. Respiratory infections require careful assessment and treatments. Diagnosis and treatment of cardiovascular comorbidities and pulmonary hypertension are of paramount importance. As of late, oxygen therapy and ventilation modalities have evolved, and are beginning to afford more personalized options.

CONCLUSIONS

As regards COPD, a personalized approach is crucial, placing the patient at the center of the care pathway and facilitating coordination between healthcare providers.

Diagnosing sleep disordered breathing in patients with chronic pulmonary disease: which test for which patient?

Overnight polysomnography should be the first-line diagnostic test in patients with severe respiratory disease. However, if access to polysomnography is limited, overnight polygraphy can be used as an alternative first-line diagnostic. https://bit.ly/3KlmFED.

Ventilatory neural drive in chronically hypercapnic patients with COPD: effects of sleep and nocturnal noninvasive ventilation

Sleep brings major challenges for the control of ventilation in humans, particularly the regulation of arterial carbon dioxide pressure (P _aCO2 ). In patients with COPD, chronic hypercapnia is associated with increased mortality. Therefore, nocturnal high-level noninvasive positive-pressure ventilation (NIV) is recommended with the intention to reduce P _aCO2 down to normocapnia. However, the long-term physiological consequences of P _aCO2 "correction" on the mechanics of breathing, gas exchange efficiency and resulting symptoms (i.e. dyspnoea) remain poorly understood. Investigating the influence of sleep on the neural drive to breathe and its translation to the mechanical act of breathing is of foremost relevance to create a solid rationale for the use of nocturnal NIV. In this review, we critically discuss the mechanisms by which sleep influences ventilatory neural drive and mechanical consequences in healthy subjects and hypercapnic patients with advanced COPD. We then discuss the available literature on the effects of nocturnal NIV on ventilatory neural drive and respiratory mechanics, highlighting open avenues for further investigation.

Factors Associated with and Prognosis Impact of Perceived Sleep Quality and Estimated Quantity in Patients Receiving Non-Invasive Ventilation for Acute Respiratory Failure

Background. The objectives of this study were (1) to determine factors associated with impaired sleep and (2) to evaluate the relationship between impaired sleep and the outcome. Methods. Secondary analysis of a prospective observational cohort study in 54 intensive care units in France and Belgium. Sleep quality was quantified by the patients with a semi-quantitative scale. Results. Among the 389 patients included, 40% reported poor sleep during the first night in the ICU and the median (interquartile) total sleep time was 4 h (2−5). Factors independently associated with poor sleep quality were the SOFA score (odds ratio [OR] 0.90, p = 0.037), anxiety (OR 0.43, p = 0.001) and the presence of air leaks (OR 0.52, p = 0.013). Factors independently associated with short-estimated sleep duration (<4 h) were the SOFA score (1.13, p = 0.005), dyspnea on admission (1.13, p = 0.031) and the presence of air leaks (1.92, p = 0.008). Non-invasive ventilation failure was independently associated with poor sleep quality (OR 3.02, p = 0.021) and short sleep duration (OR 0.77, p = 0.001). Sleep quality and duration were not associated with an increase in mortality or length of stay. Conclusions. The sleep of patients with ARF requiring NIV is impaired and is associated with a high rate of NIV failure.

Compensatory responses to increased mechanical abnormalities in COPD during sleep

PURPOSE

To assess whether night-time increases in mechanical loading negatively impact respiratory muscle function in COPD and whether compensatory increases in inspiratory neural drive (IND) are adequate to stabilize ventilatory output and arterial oxygen saturation, especially during sleep when wakefulness drive is withdrawn.

METHODS

21 patients with moderate-to-severe COPD and 20 age-/sex-matched healthy controls (CTRL) participated in a prospective, cross-sectional, one-night study to assess the impact of COPD on serial awake, supine inspiratory capacity (IC) measurements and continuous dynamic respiratory muscle function (esophageal manometry) and IND (diaphragm electromyography, EMGdi) in supine sleep.

RESULTS

Supine inspiratory effort and EMGdi were consistently twice as high in COPD versus CTRL (p < 0.05). Despite overnight increases in awake total airways resistance and dynamic lung hyperinflation in COPD (p < 0.05; not in CTRL), elevated awake EMGdi and respiratory effort were unaltered in COPD overnight. At sleep onset (non-rapid eye movement sleep, N2), EMGdi was decreased versus wakefulness in COPD (- 43 ± 36%; p < 0.05) while unaffected in CTRL (p = 0.11); however, respiratory effort and arterial oxygen saturation (SpO₂) were unchanged. Similarly, in rapid eye movement (stage R), sleep EMGdi was decreased (- 38 ± 32%, p < 0.05) versus wakefulness in COPD, with preserved respiratory effort and minor (2%) reduction in SpO₂.

CONCLUSIONS

Despite progressive mechanical loading overnight and marked decreases in wakefulness drive, inspiratory effort and SpO₂ were well maintained during sleep in COPD. Preserved high inspiratory effort during sleep, despite reduced EMGdi, suggests continued (or increased) efferent activation of extra-diaphragmatic muscles, even in stage R sleep.

CLINICAL TRIAL INFORMATION

The COPD data reported herein were secondary data (Placebo arm only) obtained through the following Clinical Trial: "Effect of Aclidinium/Formoterol on Nighttime Lung Function and Morning Symptoms in Chronic Obstructive Pulmonary Disease" ( https://clinicaltrials.gov/ct2/show/NCT02429765 ; NCT02429765).

Overnight variation in tidal expiratory flow limitation in COPD patients and its correction: an observational study

Background

Tidal expiratory flow limitation (EFL_T) is common among COPD patients. Whether EFL_T changes during sleep and can be abolished during home ventilation is not known.

Methods

COPD patients considered for noninvasive ventilation used a ventilator which measured within-breath reactance change at 5 Hz (∆Xrs) and adjusted EPAP settings to abolish EFL_T. Participants flow limited (∆Xrs > 2.8) when supine underwent polysomnography (PSG) and were offered home ventilation for 2 weeks. The EPAP pressure that abolished EFL_T was measured and compared to that during supine wakefulness. Ventilator adherence and subjective patient perceptions were obtained after home use.

Results

Of 26 patients with supine EFL_T, 15 completed overnight PSG and 10 the home study. In single night and 2-week home studies, EFL_T within and between participants was highly variable. This was unrelated to sleep stage or body position with only 14.6% of sleep time spent within 1 cmH₂O of the awake screening pressure. Over 2 weeks, mean EPAP was almost half the mean maximum EPAP (11.7 vs 6.4 cmH₂O respectively). Group mean ∆Xrs was ≤ 2.8 for 77.3% of their home use with a mean time to abolish new EFL_T of 5.91 min. Adherence to the ventilator varied between 71 and 100% in prior NIV users and 36–100% for naïve users with most users rating therapy as comfortable.

Conclusions

Tidal expiratory flow limitation varies significant during sleep in COPD patients. This can be controlled by auto-titrating the amount of EPAP delivered. This approach appears to be practical and well tolerated by patients.

Trial registration: The trial was retrospectively registered at CT.gov NCT04725500.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12931-021-01913-7.

Effect of Dietary Nitrate Supplementation on Sleep in Chronic Obstructive Pulmonary Disease Patients

PURPOSE

Poor sleep quality in chronic obstructive pulmonary disease (COPD) is a result of oxygen desaturation secondary to compromised lung function. Nitrate supplementation with dietary beetroot juice is known to elevate plasma nitrate and to increase the efficiency of oxygen utilization in non-COPD individuals; whether it is of therapeutic benefit for sleep quality in COPD has not been reported.

PATIENTS AND METHODS

In a counterbalanced within-subjects design involving 15 COPD patients as subjects, the subjects consumed either beetroot juice containing nitrate (BJ; ∼6.2 mmol NO₃ ^-) or placebo (NO₃ ^- -depleted juice) immediately before a night of polysomnographic monitoring. Nitrate was measured in plasma collected immediately after waking.

RESULTS

While BJ consumption had no effect on the amount of time spent in any sleep stages, wake-to-N2 transitions and direct wake-to-rapid eye movement sleep (REMS) transitions, hallmarks of disordered sleep, were less frequent on the BJ night than on the placebo night. In the last two hours of the BJ night, percent time in REMS increased and delta power during deep (N3) non-REMS decreased, relative to the placebo night. Collectively, the reduced frequency of atypical transitions and the normalization of non-REMS/REMS dynamics after BJ are indicative of an improvement of sleep quality. BJ also resulted in sustained elevation of peripheral oxygen saturation (SpO₂), during episodes of wake after sleep onset. Plasma nitrate was elevated nearly tenfold on the morning after BJ relative to placebo.

CONCLUSION

BJ has a normalizing effect on disordered sleep in COPD, which may be related to improved oxygen delivery.

CLINICAL TRIAL REGISTRATION

The activities of the Regional Committees for Medical and Health Research Ethics (REC) are founded on the Norwegian law on research ethics and medical research. This study was approved by NTNU/REK midt, Det medisinske fakultet, Postboks 8905, 7491 Trondheim (REK midt 2016/1360).

Tailoring the Sleep Laboratory for Chronic Respiratory Failure

"Many seemingly mundane aspects of the sleep laboratory can have outsized effects on the quality of polysomnographic data obtained from, and care provided to, patients. This is particularly true when performing polysomnography on patients with chronic respiratory failure due to various causes. This article uses a disease-based approach to review physical and protocol-based accommodations that should be considered when performing polysomnography on this patient population."