Sleep should be a time for rest, but for patients with COPD, moving into the supine position often causes more severe breathlessness.
Most of us assume that patients with COPD don’t suffer from breathlessness (orthopnoea) when they are resting in bed or sleeping. Unfortunately for many of our patients, orthopnoea in the absence of heart failure is a prominent symptom, particularly in those with more severe airflow limitation.
One study found that the prevalence of orthopnoea was as high as 79% in a cohort of ambulatory COPD patients.1 Despite this, it is a widely under-recognised symptom in clinical practice. There is emerging evidence of a strong correlation between orthopnoea and sleep disturbance in COPD patients. Recently published research on understanding the pathophysiological mechanism between airflow limitation and orthopnoea provides avenues for new therapeutic interventions.2
Sleep disturbance is commonly reported in COPD patients. Patients report difficulties in initiating and maintaining sleep as well as waking feeling poorly refreshed.3 As with orthopnoea, sleep disturbance is an under-recognised symptom, with the majority of physician consultations focusing on more visible symptoms such as daytime breathlessness, cough, exercise limitation and exacerbation frequency. Patients who report disturbed sleep are more likely to have more severe daytime symptoms and poorer quality of life and are at increased risk of exacerbations, even when researchers account for other variables including baseline dypsnoea and severity of airflow limitation. 3, 4
The mechanism of orthopnoea and sleep disturbance in COPD is thought to relate to an increase in intrinsic positive end expiratory pressure (iPEEP) in the supine position, due to increased airway narrowing and closure.2, 6 The higher iPEEP means the lungs are stiffer, resulting in a greater work of breathing and the sensation of dyspnoea occurs due to neuromechanical dissociation – basically meaning that not only is the drive to breathe high, but also that the resulting ventilation is “disappointing”.
The development of iPEEP seems to occur despite appropriate bronchodilator therapy, leaving limited therapeutic options. Nevertheless, increased recognition of the role of sleep on the quality of life of COPD patients remains important to allow clinicians to identify a potentially vulnerable cohort and ensure contributing comorbidities are screened for and appropriately managed.
These include sleep-disordered breathing, anxiety, insomnia, gastro-oesophageal reflux disease and heart failure. The importance of pulmonary rehabilitation is also highlighted as it can improve functional capacity and teach strategies to reduce dynamic hyperinflation. Patients with severe airflow limitation and sleep disturbance may also benefit from early palliative care involvement and referral to a dedicated breathlessness service, where multidisciplinary care providers can focus on symptom management.
The recognition of the role of iPEEP in the pathophysiology of sleep disturbance also raises the possibility of continuous positive airway pressure (CPAP) therapy being used as a treatment option in patients, even in the absence of sleep-disordered breathing. The theory is that the provision of CPAP may counterbalance iPEEP and reduce work of breathing in the supine position.
Orthopnoea and sleep disturbance are important symptoms to recognise in COPD patients as they are common, and are associated with more severe disease and reduced patient quality of life. Recent advances in the understanding of the pathophysiological mechanisms that underpin these symptoms allow the development of more targeted therapeutic options to be developed. Our team is conducting further research into the relationship between iPEEP in the supine position and the symptoms of orthopnoea and sleep disturbance in COPD. Once this is better established, we hope to determine whether overcoming iPEEP with CPAP therapy improves orthopnoea and sleep quality in these patients.
Dr Meera Srinivasan is a respiratory and sleep physician at Royal North Shore Hospital and a PhD candidate at the University of Sydney and the Woolcock Institute of Medical Research.
References
Eltayara, L., H. Ghezzo, and J. Milic-Emili, Orthopnea and tidal expiratory flow limitation in patients with stable COPD. Chest, 2001. 119(1): p. 99-104.
Elbehairy, A.F., et al., Mechanisms of orthopnoea in patients with advanced COPD. European Respiratory Journal, 2021. 57(3).
Ding, B., et al., A cross-sectional survey of night-time symptoms and impact of sleep disturbance on symptoms and health status in patients with COPD. Int J Chron Obstruct Pulmon Dis, 2017. 12: p. 589-599.
Stephenson, J.J., et al., Impact and factors associated with nighttime and early morning symptoms among patients with chronic obstructive pulmonary disease. Int J Chron Obstruct Pulmon Dis, 2015. 10: p. 577-86.
Shorofsky, M., et al., Impaired sleep quality in COPD is associated with exacerbations: the CanCOLD cohort study. Chest, 2019. 156(5): p. 852-863.
Uccelli, S., et al., Dyspnea During Night-Time and at Early Morning in Patients with Stable COPD is Associated with Supine Tidal Expiratory Flow Limitation. Int J Chron Obstruct Pulmon Dis, 2020. 15: p. 2549-2558.
