Effect of Sleep Deprivation on Breathlessness and Exercise Capacity in COPD

Background:

Chronic Obstructive Pulmonary Disease (COPD) is a major cause of morbidity and mortality in the world. Breathlessness and exercise limitation are cardinal symptoms in COPD with grave consequences for the patient. Even with optimal COPD treatment a large number of these patients experience a breathlessness which limits their everyday life. Physical activity is the main trigger of breathlessness in daily life, but knowledge is limited on how other factors may affect exercise performance, breathing and exertional breathlessness in patients with COPD.

Sleep deprivation is common in the population in patients with COPD, and especially in patients with worsening health status and during hospitalizations. As many as 40-45% of patients older than 70 experience sleep deprivation during hospitalization. As many as 21 % of patients with COPD have a disturbed sleep. A recent study on healthy young males who breathed against an inspiratory resistance showed that one night's sleep deprivation significantly reduced their respiratory endurance and induced worse and more disturbing breathlessness.

Little is known how sleep loss affects patients with COPD in an outpatient setting. Several studies have evaluated the effect of sleep deprivation on exercise capacity in young healthy adults. However, very few studies have examined the effect of sleep deprivation on the exercise capacity or exertional breathlessness in patients with COPD; most data pertain to observational studies where no intervention took place and data from a randomized controlled trial (RCT) is needed. The presence of disturbed sleep in patients with COPD - and especially in relation to worsenings and hospitalizations, could have a marked detrimental effect on their breathing, increase suffering from distressing breathlessness and potentially increase the risk of adverse health outcomes and worse prognosis. Directed actions to improve sleeping in these settings could in that case improve the patients' outcomes.

Aim:

To test the effect of one sleepless night on breathlessness, exercise endurance and ventilation in patients with COPD.

Method:

This is a randomized (ratio 1:1), controlled, crossover trial of the effect of one night's sleep deprivation vs. normal sleep on exercise endurance, ventilation and breathlessness in outpatients with COPD. The study will not be blinded for participants and staff (due to the nature of the intervention) but will be blinded for the analyst.

The intervention is one night without sleep, and the control is one night with normal sleep. The test is a bicycle test (exercise test on a bike with continuous analysis of ventilation and gaseous exchange) carried out as a sub-max test at 75% of maximum capacity until the test person cannot go on.

The study consists of three visits. At the first visit, informed consent is collected, and inclusion and exclusion criteria are evaluated. Also, information is collected regarding the person's COPD-diagnosis, medication, and other illnesses. Specific surveys are Pittsburgh Sleep Quality Index (PSQI), COPD Assessment Test (CAT), modified Medical Research Council (mMRC) scale, 7-point Global Impression of Change (GIC) scale, Experienced sleep quality (Likert scale), Multidimensional Dyspnea Profile (MDP) to assess the person's sleep and respiration. Baseline values for dynamic spirometry, saturation, and blood pressure are also measured during the first visit. Afterwards, a bicycle test is carried out according to normal clinical standards. This involves increasing the resistance (in Watts) according to a set protocol until the test person is unable to continue. This takes roughly 6-10 minutes and provides a maximum performance value for the individual. This maximum value is used for visit number two and three. After this first visit the order of the sleepless night is randomized for either visit two or three.

At the second and third visit spirometry, saturation and blood pressure are once more measured. The person is evaluated for contraindications. Then a new bicycle test is carried out at 75% of the maximum W achieved at the first visit. The test takes around 10 minutes, and continues until the person is unable to continue. During this test, ventilation is measured as respiratory rate (RR), minute ventilation (MV), oxygen consumption (VO2), carbon dioxide consumption (VCO2), the respiratory quotient (VCO2/VO2), inspiratory capacity manoeuvre (IC), dynamic hyperinflation, ventilatory reserve capacity, ventilation efficiency (MV/VCO2-curve) and the anaerobic threshold. During the test the person is also assessed for how difficult the breathing feels (0-19 Borg CR10), how tired the legs feels (Borg CR10), how uncomfortable the breathing feels (mBorg 0-10) every two minutes and at the end of the test. At the end of the test the test person is asked about the reason for ending the test, how the breathing was experienced (Multidimensional Dyspnea Profile, MDP), and how motivated they were to carry out the test (0-10 NRS). The person is also monitored with EKG during the test, and the blood pressure is measured every two minutes. The results are then compared between the test where the person had a normal night's sleep, and the test where the person was awake the whole night before.

The normal night's sleep is assessed using some simple questions, such as: "How did you sleep tonight" and "How satisfied are you with the night's sleep?". It is also evaluated using an Actigraph bracelet that measures movement when worn. The bracelet is worn for 48 hours preceding both tests.

The night when the person is going to be awake is spent at the test lab, after eating a normal dinner at home. They then spend an entire night in a room where they can watch TV, use a phone or tablet or read books and magazines. They will be monitored by staff to help them stay awake during the night. They cannot eat, drink or smoke anything not usually consumed during the night (other than water). They then eat a normal breakfast of their choosing, and the test is carried out just like the one where they slept normally.