Tuyển tập các báo cáo nghiên cứu về y học được đăng trên tạp chí y học Critical Care cung cấp cho các bạn kiến thức về ngành y đề tài: Saline volume expansion and cardiovascular physiology: novel observations, old explanations, and new questions. | Available online http content 8 5 315 Commentary Saline volume expansion and cardiovascular physiology novel observations old explanations and new questions James L Robotham Professor and Chairman Department of Anesthesiology University of Rochester Rochester New York USA Corresponding author James L Robotham james_robotham@ Published online 1 September 2004 This article is online at http content 8 5 315 2004 BioMed Central Ltd Related to Research by Kumar et al. see issue page 201 Critical Care 2004 8 315-318 DOI cc2944 Abstract In a clinical investigation Kumar and coworkers reported the hemodynamic events that accompany plasma volume expansion over 3 hours in healthy adult volunteers and found that increases in stroke volume SV may be related to increases in left ventricular LV right ventricular RV end-diastolic volume as they expected but also to decreases in LV RV end-systolic volume. The latter finding suggests increased contractility and or decreased afterload which do not fit with their perception that clinicians ascribe increases in SV to increases in end-diastolic volume based on Starling s work. Increased ejection fraction and decreased vascular resistances were also observed. The same authors recently reported novel data suggesting that reduced blood viscosity may account for the observed reduction in vascular resistances with saline volume expansion. However the variances in preload and afterload along with uncertainty in estimates of contractility substantially limit their ability to define a primary mechanism to explain decreases in LV end-systolic volume. A focus on using ejection fraction to evaluate the integrated performance of the cardiovascular system is provided to broaden this analytic perspective. Sagawa and colleagues described an approach to estimate the relationship under clinical conditions between ventricular and arterial bed elastances . maximal ventricular systolic elastance .
