Left Ventricular-arterial Coupling In Septic Shock

Objectives:(1) To investigate the variations of left ventricular-arterial coupling in the resuscitation of refractory septic shock, and its prognostic value.(2) To investigate the variations of left ventricular-arterial coupling and its compensatory potentiality in septic shock, and to explore the mechanisms of these variations. To attempt the way to control ventricular-arterial coupling.(3) To investigate the optimal left ventricular-arterial coupling in septic shock.Methods:(1)58patients with refractory septic shock continuously admitted to our department from January2010to July2011were retrospectively studied. Hemodynamic data, arterial lactate concentration and APACHE II (acute physiology&chronic health evaluation Ⅱ)score at the beginning of and24hours after cardiac output monitoring, as well as the outcome of Day28post-diagnosis were recorded. Stroke volume index(SVI),cardiac index(CI) and global end-diastolic volume index(GEDVI) were obtained through transpulmonary thermodilution technique by using pulse induced continuous cardiac output (PiCCO) system. Left ventricular end-systolic volume index (LVESVI) was approximated to (GEDVI/4-SVI),and effective arterial elastance index/ventricular end-systolic elastance index(Eal/EesI) was approximated to LVESVI/SVI.(2) Septic shock rabbits were constructed by intravenous injection of endocrine(LPS).12rabbits were divided into two groups randomly,S group(sham operation group,n=6) and E group(endocrine injection group,n=6).Norepinephrine tests were carried out at0h(30min after operation),2h(1h after endocrine or normal sodium injection) and4h(3h after endocrine or normal sodium injection).Echocardiogram examination and hemodynamic monitor were performed and the relative parameters were recorded before and after each norepinephrine test.(3)18rabbits with septic shock induced by intravenous endocrine injection were divided into3groups randomly, C group(septic shock control group, n=6), F group(maximal work efficiency group,n=6), W group(maximal stroke work group,n=6).Ea/Ees of F group was regulated and maintained at around0.57from the beginning of1h after endocrine injection, while Ea/Ees of W group was regulated and maintained at around0.80from the beginning of1h after endocrine injection. Hemodynamic parameters were recorded at0h(30min after operation),1h (1h after endocrine injection),3h (3h after endocrine injection) and5h(5h after endocrine injection) in all the three groups,and additionally, in F and W groups, patameters of1NE time point(the time point right after targeted Ea/Ees regulated by norepinephrine)were also recorded.Oxygen pressure of artery(PaO2), oxygen saturation of central vein(ScvO2),concentrations of lactate (Lac),troponin I(cTnI),B-type natriuretic peptide(BNP) and creatinine(Cr) in artery, and transcutaneous oxygen pressure(PtcO2)of Oh,1h,3h and5h were examined. All the rabbits were executed and tissues of heart,ascending aorta and kidney were cut for HE dyeing after5h examination.Results:[1](1) Binary Logistic regression analysis showed that AEa/Ees and APACHE II score at the24th hour were the independent risk factors of death for refractory septic shock, and the OR value of AEa/Ees was higher than that of APACHE II score(2.04vs1.63).(2) APACHE II score at the24th hour,24hs Ea/Ees variation(AEa/Ees) and24hALac were higher in non-survivors than those in survivors,24hs lactate clearance rate (rLac) was lower in non-survivors, p<0.05.(3) All the hemodynamic parameters at the beginning had no difference betweenAEa/Ees>0group and AEa/Ees≤0group. CI, SVI, EGDT(early goal-directed therapy) compliance rate at the24th hour in AEa/Ees>0group were lower than those in AEa/Ees<0group. The effective arterial elastance index(EaI) and Ea/Ees at the24th hour and the mortality rate of Day28in AEa/Ees>0group were higher than those in AEa/Ees<0group.(4) During the24hs treatment,AEa/Ees correlated negatively to the variations of CI, SVI, EesI and rLac, and positively to the variations of heart rate, GEDVI, systolic vascular resistance index(SVRI) and EaI.[2](1)In E group, ventricular end-systolic elastance (Ees) of2h and4h were both lower than that of Oh significantly,p<0.05.There was no significant difference between effective arterial elastance/ventricular end-systolic elastance (Ea/Ees)of2h and that of Oh, p>0.05.Ea/Ees of4h was higher than that of Oh significantly,p<0.05.(2)In E group, systemic vascular resistance (SVR) and aortic augmentation index (AAIX) of2h and4h were lower than those of Oh significantly,and aorta-femoral pulse wave velocity (PWV) was higher than that of Oh significantly,p<0.05.(3)Ees,stroke volume (SV),cardiac output(CO),left ventricular end-diastolic compliance (Ced),central vein pressure(CVP),left ventricular end-diastolic pressure (LVQP),left ventricular end-diastolic volume (LVDV),stroke work(SW),pressur-volume area(PVA),work efficiency (Ef),SV/LVDV,SW/LVDV and Ef/LVDV moved with Ea/Ees coincidently at each examining point.(4) In E group,the maximums of Ees,SV,CO,Ced,SW,Ef, SV/LVDV,SW/LVDV and Ef/LVDV of Oh,2h and4h declined gradually. The maximums of SV,SW and SW/LVDV of Oh and2h all directed Ea/Ees at around0.80,and the maximums of Ced,Ef, Ef/LVDV and SV/LVDV of Oh and2h all directed Ea/Ees at around0.57.(5)In E group, at each examining point, Ea/Ees rised with ASP increasing.[3](1)Aortic systolic pressure(ASP),CVP,SV,LVDV,LVQP,Ea,Ea/Ees,SW and PVA at1NE in W group were higher than those in F group significantly, and Ced,Ees and Ef at1NE in W group were lower than those in F group significantly, p<0.05.(2)In F group,there were no significant differences of ASP,CVP,SV, CO,LVDV,LVQP,Ced,Ea,Ees,Ea/Ees,SW,PVA and Ef among all the examining time point.In W group, CVP,LVDV and LVQP at5h were higher than those at1NE significantly, and ASP,Ea,Ees,SW and PVA at5h were lower than those at1NE significantly,p<0.05,and there were no significant differences of SV,CC,Ea/Ees and Ef among all the examining point.(3)There were no significant differences of oxygen delivery(DO2),oxygen consumption(V02) and ScvO2between F and W group,p>0.05. Lac and PtcO2/PaO2at5h in W group were higher than those in F group significantly, and BNPs at3h and5h in W group were higher than those in F group significantly,p<0.05.(4) Pathological damages of heart,ascending aorta and kidney in W group were severer than those in F group.Conclusions:[1](1)AEa/Ees can be used as a good marker to predict the outcome of refractory septic shock;(2)Lowing Ea/Ees in the resuscitation has beneficial effects on EGDT compliance, lactate clearance and outcome;(3)Helpful effects of lowing Ea/Ees on tissue perfusion maybe caused by the variations of SVI and EaI;(4)The effect of lowing Ea/Ees on SVI increase maybe contributed to lowing EaI.[2](1) There was no significant variation of left ventricular-arterial coupling in the early phase of septic shock,but significant uncoupling occurred in the late phase because of much lowing of myocardial contractility compared with ventricular afterload.(2) The elastance variations of elements in arterial system were not coincidental in septic shock.(3)The compensatory potentialities of ventricular systole and diastole,ventricular work,SV/LVDV,SW/LVDV and Ef/LVDV were all influenced by left ventricular-arterial coupling,and some of them were decidedly. Circulatory compensatory potentialities were decreased in septic shock, including compensatory potentiality of left ventricular-arterial coupling.(4)The way to regulate left ventricular-arterial coupling by adjusting aortic blood pressure was practical.(5)States of maximal SV,SW and work efficiency could be accomplished by controlling left ventricular-arterial coupling.[3](1)Optimal left ventricular-arterial coupling achieves the maximal work efficiency.(2)Much more damages of cardiac functions,vascular structure,systemic tissue perfusion,skin perfusion and renal function occurred in the state of maximal stroke work and maximal stroke volume compared with the state of maximal work efficiency.