Mateika Jason H, Demeersman Ronald E, Kim Jaehee
John D. Dingell Veterans Affairs Medical Center, Detroit, MI 48201, USA.
Clin Auton Res. 2002 Feb;12(1):24-34. doi: 10.1007/s102860200007.
The purpose of the present investigation was to examine the effect of lung volume and inspiration of 100% oxygen on blood pressure and R-R interval responses during the Valsalva maneuver.
Fourteen healthy subjects completed eight Valsalva maneuvers. Four of the maneuvers were completed after inspiring to total lung capacity while the remaining maneuvers were completed at end-expiratory lung volume. Two maneuvers completed at a given lung volume were performed under hyperoxic conditions while the remaining maneuvers were completed under normoxic conditions.
Overall, a significant increase in blood pressure and decrease in R-R interval occurred throughout phases I-IV of the Valsalva maneuvers that were initiated from end-expiratory lung volume as compared to total lung capacity. These changes were accompanied by a concomitant increase in baroreflex sensitivity during phase IV. Furthermore, independent of lung volume the baroreflex response was attenuated under hyperoxic conditions.
We conclude that the lung volume that exists prior to the onset of the maneuver alters the blood pressure and R-R interval response during phases I-IV of the Valsalva maneuver. Furthermore, we suggest that these responses are mediated in part by changes in chemoreceptor activity since the baroreflex was reset and the sensitivity was reduced under hyperoxic conditions. Given these findings, we recommend that lung volume be controlled when patients are completing a Valsalva maneuver to obtain reliable and reproducible measures of blood pressure, R-R interval duration and baroreflex sensitivity.
本研究旨在探讨肺容积及吸入100%氧气对瓦尔萨尔瓦动作期间血压和R-R间期反应的影响。
14名健康受试者完成了8次瓦尔萨尔瓦动作。其中4次动作是在吸气至肺总量后完成的，其余动作是在呼气末肺容积时完成的。在给定肺容积下完成的2次动作是在高氧条件下进行的，其余动作是在常氧条件下完成的。
总体而言，与肺总量相比，从呼气末肺容积开始的瓦尔萨尔瓦动作的I-IV期，血压显著升高，R-R间期缩短。这些变化伴随着IV期压力反射敏感性的相应增加。此外，与肺容积无关，在高氧条件下压力反射反应减弱。
我们得出结论，动作开始前存在的肺容积会改变瓦尔萨尔瓦动作I-IV期的血压和R-R间期反应。此外，我们认为这些反应部分是由化学感受器活动的变化介导的，因为在高氧条件下压力反射被重置且敏感性降低。鉴于这些发现，我们建议在患者进行瓦尔萨尔瓦动作以获得可靠且可重复的血压、R-R间期持续时间和压力反射敏感性测量值时，应控制肺容积。
