Differences in P-wave mean and Pd in ms during breathing manoeuvres in all patients (n = 57).

<p>Differences in P-wave mean and Pd in ms during breathing manoeuvres in all patients (n = 57).</p

Simulated Obstructive Sleep Apnea Increases P-Wave Duration and P-Wave Dispersion

<div><p>Background</p><p>A high P-wave duration and dispersion (Pd) have been reported to be a prognostic factor for the occurrence of paroxysmal atrial fibrillation (PAF), a condition linked to obstructive sleep apnea (OSA). We tested the hypothesis of whether a short-term increase of P-wave duration and Pd can be induced by respiratory manoeuvres simulating OSA in healthy subjects and in patients with PAF.</p><p>Methods</p><p>12-lead-electrocardiography (ECG) was recorded continuously in 24 healthy subjects and 33 patients with PAF, while simulating obstructive apnea (Mueller manoeuvre, MM), obstructive hypopnea (inspiration through a threshold load, ITH), central apnea (AP), and during normal breathing (BL) in randomized order. The P-wave duration and Pd was calculated by using dedicated software for ECG-analysis.</p><p>Results</p><p>P-wave duration and Pd significantly increased during MM and ITH compared to BL in all subjects (+13.1ms and +13.8ms during MM; +11.7ms and +12.9ms during ITH; p<0.001 for all comparisons). In MM, the increase was larger in healthy subjects when compared to patients with PAF (p<0.05).</p><p>Conclusion</p><p>Intrathoracic pressure swings through simulated obstructive sleep apnea increase P-wave duration and Pd in healthy subjects and in patients with PAF. Our findings imply that intrathoracic pressure swings prolong the intra-atrial and inter-atrial conduction time and therefore may represent an independent trigger factor for the development for PAF.</p></div

Mean P-wave duration measured in a single lead over all sectors (95% CI).

<p>The two sectors which comprise the manoeuvres are shaded grey. We observed significant differences for ITH and MM vs BL during the manoeuvre (both p<0.001). The P-wave duration did not change during the course of the BL (p = 0.99) and AP (p = 0.94) manoeuvre. All analyses were adjusted for PAF status, heart rate, age, BMI, and sex. BL = baseline (normal breathing). ITH = inspiration through a threshold load (simulating an obstructive hypopnea). MM = Mueller manoeuvre (simulating an obstructive apnea). AP = end-expiratory breath holding (simulating central apnea).</p

Clinical characteristics by study population.

<p>Clinical characteristics by study population.</p

Study profile.

<p>Study profile.</p

Scatterplots showing the relationship between <i>FEV₁ (%predicted)</i> and the total energy expenditure as assessed by accelerometry, TEE_ACC (black squares) (r = 0.32, 95% 0.09 to 0.52, p = 0.011) and by the Zutphen Physical Activity Questionnaire, TEE_ZPAQ (white dots) (r = 0.31, 95% CI 0.81 to 0.51, p = 0.012), respectively.

<p>Patients with COPD seem to underestimate their daily PA level.</p

Physical Performance.

<p>Values are presented as mean (SD). PAL: physical activity level; MET: metabolic equivalent; TEE_ACC: total energy expenditure per day as assessed by accelerometry; TSA>3METs: time spend per day in activities demanding more than 3 metabolic equivalents; steps/day: number of steps per day; TEE_ZPAQ: total energy expenditure per day as assessed by the Zutphen Physical Activity Questionnaire.</p

Anthropometrics and Pulmonary Function.

<p>Values are presented as mean (SD). BMI: body mass index; FEV₁: forced expiratory volume in one second; FEV₁/FVC ratio: forced expiratory volume in 1 sec (FEV₁) expressed as percent of FVC; DLCO: diffusion capacity for carbon monoxide; TLC: total lung capacity; RV/TLC: residual volume/total lung capacity ratio; PaO₂: partial pressure of oxygen; PaCO₂: partial pressure of carbon dioxide.</p

Multiple Regression Analysis of Predictors of Physical Activity (Steps per Day).

<p>6MWT: 6-Minute Walk Test; STST: <i>Sit-</i>to-<i>Stand Test;</i> TEE_ZPAQ: total energy expenditure per day as assessed by the Zutphen Physical Activity Questionnaire; PaO₂: partial pressure of oxygen; FEV₁: forced expiratory volume in one second; BMI: body mass index.</p

Correlations with Average Steps per Day.

<p>Correlation is expressed as Pearson’s correlation coefficient. MET: metabolic equivalent; TEE_ACC: total energy expenditure per day as assessed by accelerometry; TSA>3METs: time spend per day in activities demanding more than 3 metabolic equivalents; TEE_ZPAQ: total energy expenditure per day as assessed by the Zutphen Physical Activity Questionnaire.</p