急性高容量血液稀释对OLV犬血管外肺水的影响—温度稀释法与重量分析法的比较

Effects of acute hypervolemic hemodilution on extravascular lung water during one-lung ventilation: evaluation of accuracy of the transthoracic thermodilution system(PiCCO)

目的 采用温度稀释法(PiCCO系统)单肺通气(OLV)下急性高容量血液稀释(AHHD)对犬血管外肺水(EVLW)的影响,并应用重量分析法验证其结果的准确性。方法 16只健康成年杂种犬,随机分为双肺通气(DLV)组和OLV组,每组8只。肌肉注射氯胺酮8mg·kg^(-1)麻醉后,注射硫喷妥钠、维库溴铵快速诱导插管后,行间歇正压通气(吸入氧浓度为100％)。置入颈外静脉导管及股动脉热稀释导管,与PiCCO监测仪连接,用低于8℃的生理盐水5ml快速推入颈外静脉导管,进行数据监测。OLV组右开胸行左肺单侧通气,操作完成后稳定15min,经犬外周静脉以80ml·kg^(-1)·h^(-1)的速率输入6％中分子羟乙基淀粉,分别将红细胞压积(Hct)降至25％(H_1)、20％(H_2)、15％(H_3)水平。达到H_3水平后立即静脉注射大剂量硫喷妥钠将实验犬处死,摘取左右侧肺。分别在麻醉后即刻(C_1)、开胸OLV后(C_2)、用闭胸器将胸腔闭合后(C_3)、Hct稀释至H_1、H_2、H_3时监测心率(HR)、平均动脉压(MAP)、中心静脉压(CVP)、心输出量(CO)、胸内血容量(ITBV)、全心舒张末容积(GEDV)、EVLW;以重量分析法检测EVLW。结果 与C_1比较,DLV组CVP、CO、GEDV、ITBV在H_(1-3)时、EVLW在H_(2-3)时升高(P<0.05或0.01),OLV组各时点差异无显著性(P>0.05)。与C_2比较,OLV组在C_3、H_(1-3)时CVP?

Objective To evaluate the effects of different degrees of acute hypervolemic hemodilution (AHHD)on extravascular lung water(EVLW) during one-lung ventilation(OLV) using PiCCO and compare the results with those obtained by gravimetric method. Methods Sixteen healthy adult mongrel dogs weighing 12-21kg were randomly divided into 2 groups: OLV group(A, n=8)and two-lung ventilation(TLV) group(B, n=8). The animals were premedieated with intramuscular ketamine 8 mg·kg^(-1) and anesthetized with thiopental and vecuronium and were mechanically ventilated with 100% O_2 after tracheal intubation. A CVP line was established via external jugular vein and a 4F thermodilution catheter was inserted via femoral artery and connected to a transthoraeic thermodilution system(PiCCO, Pulsion). Cold normal saline(<8℃) 5ml was injected rapidly through CVP line 3 times and the mean value was obtained. In OLV group the endotracheal tube was first inserted into the right main bronchus. The left lung was deflated after thoracotomy, then the left main bronchus was clamped and the endobronehial tube was withdrown back to trachea. 15 min after instrumentation, 6% HES was infused at a rate of 80 ml·kg^(-1)·h^(-1) and Hct was reduced step by step to 25%(H_1), 20%(H_2)and 15%(H_3). MAP, HR, CVP, cardiac output(CO) intrathoracic blood volume(ITBV), global end-diastolic volume(GEDV) and EVLW were measured and recorded after induction of anesthesia(C_1)after OLV was established(C_2), when the chest was closed(C_3) and at H_1, H_2 and H_3. The animals were sacrificed after H_3. The wet lung weight and dry lung weight were measured and EVLW was calculated. Results CVP increased significantly after OLV was started at C_2 and C_3 and increased further during AHHD at H_1, H_2 and H_3 in both groups(P<0.01). CO, GEDV and ITBV increased significantly at all levels of AHHD(H_1, H_2, H_3)compared with baseline values in both groups (P<0.01). In OLV group EVLW increased significantly at all levels of AHHD(H_1, H_2, H_3) while in TLV group only at H_2 and H_3 compared with the baseline value at C_1(P<0.05 or 0.01). EVLW was significantly greater in OLV group than that in TLV group at H_2 and H_3(P<0.05 or 0.01). Three animals in OLV group showed clinical signs of pulmonary edema at H_2 and H_3. The EVLW measured by PiCCO was significantly greater than that by gravimetric method but they were closely correlated. Conclusion EVLW is overestimated by PiCCO compared with that calculated by gravimetric method, but they are closely correlated. ITBV can reflect the changes in preload during OLV. The increase in EVLW induced by AHHD with 6% HES is significantly larger during OLV than that during TLV. Pulmonary edema should be avoided.