Tuyển tập các báo cáo nghiên cứu về y học được đăng trên tạp chí y học Critical Care giúp cho các bạn có thêm kiến thức về ngành y học đề tài: Pulse pressure variation, stroke volume variation and dynamic arterial elastance. | Giraud et al. Critical Care 2011 15 414 http content 15 2 414 CRITICAL CARE LETTER L_ Pulse pressure variation stroke volume variation and dynamic arterial elastance Raphael Giraud Nils Siegenthaler and Karim Bendjelid See related research by Monge Garcia etal. http content 15 1 R15 We read with interest the recent article by Monge Garcia and colleagues 1 . We have two comments regarding this interesting physiological study. First although we support their observation 2 their explanations may lead to some confusion. Indeed the Edwards VigileoTM system-FloTracTM sensor calculates stroke volume SV using the equation SV Khi X ƠÀP where ƠÀP is the standard deviation of the arterial pressure ÀP curve and Khi a constant quantifying arterial elastance and vascular resistance 3 . Às stroke volume variation SVV SVV in SVmax - SVmin SV mean SVV Khi X ơÀPmax - Khi X ơÀPmin Khi X ơÀPmean SVV Khi X ơÀPmax - ơÀPmin Khi X ơÀPmean SVV ơÀPmax - ơÀPmin ơÀPmean SVV PPmax - PPmin PPmean Which means that SVV pulse pressure variation PPV for FloTrac . With the present mathematical equation it can be demonstrated that the SVV calculated by FloTracTM SVVFT is not influenced by Khi which means that SVVFT calculation does not include effective arterial elastance Ea . The originality of Garcia and colleagues finding is that they realized that when measuring PPV conventionally 4 the ratio PPV SVVFT becomes a mirror of a dynamic Ea as the conventional PPV selected integrates Khi Figure 1 . However when the present innovative method is used PPV and SVV should be sampled during the same period of time. In conclusion we believe that dynamic Ea predicting arterial pressure response to volume loading in preloaddependent patients is an interesting physiological concept. However this demonstration cannot be achieved without taking into consideration the impact of PPV SVV sampling. Abbreviations APZ arterial pressure Ea arterial elastance PP pulse pressure PPV pulse .
