Parker J D, Brooks D, Kozar L F, Render-Teixeira C L, Horner R L, Douglas Bradley T, Phillipson E A
The Department of Medicine, University of Toronto, Mount Sinai Hospital, Toronto, Ontario, Canada.
Am J Respir Crit Care Med. 1999 Dec;160(6):1888-96. doi: 10.1164/ajrccm.160.6.9807074.
We used a canine model of chronic obstructive sleep apnea (OSA) to examine the effects of intermittent airway occlusion during sleep on left ventricular (LV) performance. Studies were performed in four dogs. The effects of acute airway occlusion on LV pressure and volume (on a background of chronic OSA) were determined with an impedance catheter and a high fidelity manometer. In conscious animals (n = 3), experiencing spontaneous episodes of sleep, acute airway occlusion caused significant increases in LV transmural systolic pressure that were associated with increased end-systolic volume and reduced stroke volume. To determine the effects of chronic OSA on baseline LV function, two-dimensional echocardiograms were performed in conscious animals (n = 4) during unobstructed breathing before and after a 1- to 3-mo period of OSA. During chronic OSA, there was a significant decrease in LV ejection fraction as a result of increases in end-systolic volume. We conclude that in chronic OSA acute airway occlusion during sleep is associated with increases in LV afterload and decreases in fractional shortening. Chronic OSA also leads to sustained decreases in LV systolic performance that could be caused by the development of systemic hypertension and/or transient increases in LV afterload during episodes of airway obstruction.
我们使用慢性阻塞性睡眠呼吸暂停（OSA）犬模型来研究睡眠期间间歇性气道阻塞对左心室（LV）功能的影响。对四只犬进行了研究。使用阻抗导管和高保真压力计测定急性气道阻塞对LV压力和容积（在慢性OSA背景下）的影响。在清醒动物（n = 3）中，经历自发睡眠发作时，急性气道阻塞导致LV跨壁收缩压显著升高，这与收缩末期容积增加和每搏输出量减少有关。为了确定慢性OSA对基线LV功能的影响，在1至3个月的OSA前后，对清醒动物（n = 4）在通畅呼吸期间进行二维超声心动图检查。在慢性OSA期间，由于收缩末期容积增加，LV射血分数显著降低。我们得出结论，在慢性OSA中，睡眠期间的急性气道阻塞与LV后负荷增加和缩短分数降低有关。慢性OSA还导致LV收缩功能持续下降，这可能是由系统性高血压的发展和/或气道阻塞发作期间LV后负荷的短暂增加引起的。
