21天头低位卧床状态下心功能的变化及套带的作用

Cardiac dynam icsduring 21 d head-down bedrestwith and withoutcuffs JIANGChanglin, JIANG Shizhong,

目的 研究模拟失重状态下心功能的变化及套带的防护作用。 方法 １２ 名受试者，随机分为对照组和套带组，进行了２１ 天头低位卧床试验。套带组卧床第１～１０、１８～２１ 天每天８：３０～２０：３０ 四肢戴加压套带，压力维持在（５．３±０．７） ｋＰａ，第１１～１７ 天不使用套带；对照组卧床中不用任何对抗措施。在卧床前１ 天、卧床第２、３、４、６、９、１３、１７、２１ 天和卧床后第３ 天，用科飞ＳＦ－ＩＶ心肺功能检查仪检测ＳＶ、ＣＯ和ＳＴＩ。 结果 对照组卧床中ＳＶ、ＣＯ较卧床前明显下降，卧床后第３ 天回升，反高于卧床前，对照组卧床中ＬＶＥＴ 缩短，ＰＥＰ、ＩＣＴ、ＰＥＰ／ＬＶＥＴ、ＩＣＴ／ＬＶＥＴ 延长，卧床后第３天恢复至卧床前水平；套带组卧床中ＳＶ、ＣＯ 也较卧床前下降，但下降幅度轻于对照组，卧床后第３天回升，幅度也轻于对照组，套带组卧床中ＬＶＥＴ 缩短，ＰＥＰ、ＩＣＴ、ＰＥＰ／ＬＶＥＴ、ＩＣＴ／ＬＶＥＴ延长，使用套带时比不使用套带时变化更明显，卧床后第３ 天恢复至卧床前水平。 结论 ２１ 天头低位卧床使心泵血功能下降，这可能与体液丢失、前负荷减少有关。使用四肢持续加压套带通过对抗体液头向转移，维持有效血容量和前负荷，一定程?

Objective To investigate cardiac dynam ics during 21 d head dow n - 6°tilt w ith and w ithout cuffs. Methods The - 6°head dow n bed rest 21 d w as used to sim ulate w eightless- ness. Tw elve volunteers w ere divided into 2 groups: cuffs group and controlgroup. In cuffs group, cuffs on the upperpartofthighs and arm s w ere inflated 12 h/d during 1-10 d,18-21 d ofbed restand cuffs w ere rem oved during 11-17 d ofbed rest. No counterm easure w as used in controlgroup. SV, CO and STIw erem easured before, during and afterhead-dow n bedrest(HDBR). Results In con- trolgroup, SV, CO w eresignificantly low erthan initialvalue during bed restand gone up to the lev- elhigher than the initialvalues 3 daysafterbed rest; LVET w asless w hile PEP, ICT, PEP/LVET, ICT/LVET w ere higherthan those beforebed rest, and return to initialvalues 3 days afterbed rest. In cuffs group the decrem ent of SV, CO w as less significant than control group w hen cuffs w ere used, and the gone up value 3 days afterbed restw as less prom inent, w hile the changes ofSTIw ere sim ilar to those of controlgroup. Conclusions It is suggested that the low ering of cardiac pum p function during HDBR m ay be related w ith the loss ofbody fluid and decrem ent of cardiac preload. The sustained pressure exerted on the extrem ities by the cuffs m ay inhibitthe shiftofbody fluid to- w ards the head, so that the decrem ent of effective blood volum e and preload as w ellas the cardiac pum p function can be alleviated.