<p>Dyspnea During Night-Time and at Early Morning in Patients with Stable COPD is Associated with Supine Tidal Expiratory Flow Limitation</p>

Abstract

Patients with chronic obstructive pulmonary disorder (COPD) complain of various COPD-related symptoms with different daily frequencies. During the night-time and at early morning, dyspnea is often reported and may predict an increased risk of COPD exacerbation and hospitalization and all-cause mortality. The aim of the study was to assess the underlying mechanisms of this symptom, seeking functional biomarkers of its occurrence. Methods: Stable COPD patients with moderate-to-severe airflow obstruction and without confounding comorbidities underwent extensive baseline function respiratory tests. Spirometry, maximal flow-volume curves, lung volumes, and lung diffusion capacity parameters were obtained. Inspiratory capacity was also measured both in seated and supine positions. Forced oscillation technique (FOT) and negative expiratory pressure (NEP) method were used to establish the presence of tidal expiratory flow limitation (EFL) during recumbency. Questionnaires for recording COPD-related symptoms were administered. Sleep-related disturbances reported by the patients were also registered. Results: Forty-two consecutive COPD patients aged 65±9 completed the protocol. They were divided, according to the absence (NFL) or presence (FL) of supine EFL, in NFL group (n=17) and FL group (n=25). FL COPD patients had more severe airflow obstruction (FEV 1 = 46.4±19.4 vs 65.1±12.5% pred., p<0.01) and they showed no increase of supine IC in contrast with NFL COPD patients (ΔIC= 0.080±0.18 vs 0.390±0.28 L, p<0.01). Dyspnea either during night-time and at early morning was significantly more reported in FL COPD patients than in NFL COPD patients (p<0.05) and in those with less than 10% increase in supine IC (p<0.05). Conclusion: Supine EFL is frequently associated with both night-time and early morning dyspnea, suggesting that the development of recumbent dynamic pulmonary hyperinflation, heralded by the lack of increment of IC in supine position, is a pivotal mechanism of this symptom. No or trivial increase in supine IC may indicate the occurrence of dyspnea under these conditions.

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

“…We used the novel ExpiraFlow technology to determine dynamically the presence of EFL T and the amount of EPAP required to overcome it. Like others [ 5 , 6 , 23 ] we found that substantially more of our COPD patients developed EFL T when supine than erect. Our estimate of the presence of EFL T is more conservative than other systems as there was 3 cmH 2 O of EPAP present in our ventilator circuit to ensure its effective operation.…”

“…The main effect of postural change on EFL T is mediated by a fall in end-expiratory lung volume [ 6 , 23 ] something that also occurs in a state-dependent way during sleep [ 24 ]. Our data showed marked within night variation in the need for additional EPAP to abolish EFL T , although the reasons for this are likely to be multifactorial.…”

Network analysis of symptoms, physiological, psychological and environmental risk factors based on unpleasant symptom theory in patients with chronic heart failure

“…Fatigue is a common complaint among CHF patients and can be attributed to reduced gas exchange. Additionally, CHF affects respiratory function, and experiencing dyspnea at night can disrupt sleep quality, leading to difficulty sleeping (Uccelli et al, 2020). Identifying these core symptoms is crucial for understanding the dynamics of symptoms in CHF and has significant implications for managing and intervening in these symptoms to improve overall patient health.…”

Phenotyping OSAH patients during wakefulness

“…The obstructive sleep apnea-hypopnea (OSAH) syndrome has entered the precision medicine era [1]. Once the diagnosis is made, disease severity, biological activity, and the impact on the patient's life are all domains that may and should be evaluated in patients suffering from OSAH in order to choose the best therapeutic approach [1][2][3][4]. Recent studies have pointed out that OSAH is a heterogeneous disorder with different underlying pathophysiological mechanisms that are considered relevant in the development and maintenance of OSAH.…”