大鼠严重烧伤后早期心功能和脏器血流量的变化及关系

目的 了解大鼠严重烧伤后早期迅即发生的心功能和脏器血流量变化规律及关系.方法 将36只SD大鼠按随机数字表法分为假伤组(6只)和烧伤组(30只).烧伤组大鼠制成30%TBSA Ⅲ度烧伤模型,并设伤后10、30 min及1、3、6 h共5个时相点(每时相点6只);假伤组用37℃温水致假伤.检测2组大鼠心率、平均动脉压(MAP)、左心室收缩压(LVSP)、左心室舒张末期压(LVEDP)、左心室压力最大上升/下降速率(LV±dp/dt max),并以荧光微球法检测大鼠心脏、大脑、肾、脾、胃、回肠血流量.对LV±dp/dt max与心肌血流量进行相关性分析. 结果 (1)与假伤组比较,烧伤组大鼠伤后心率逐渐下降;伤后10 min,MAP、LVSP、LV+dp/dt max、LV-dp/dt max及心肌血流量均明显降低(F值分别为12.062、12.629、11.066、18.374、9.468,P值均小于0.01),其中心肌血流量由(6.8±0.8)mL·min~(-1)·g~(-1)降至(2.6±0.5)mL·min~(-1)·g~(-1).而后随着时间的推移,上述各指标逐渐回升,伤后1 h达最高值(LV-dp/dt max除外),此后再次降低,伤后3、6 h均显著低于假伤组(各指标F值同前,P值均小于0.01).烧伤组各时相点LVEDP与假伤组接近(F=1.205,P值均大于0.05).(2)与假伤组比较,烧伤组大鼠伤后10 min肾、脾、胃、回肠血流量亦明显下降(F值分别为22.694、20.856、12.653、7.293,P<0.05或P<0.01),但下降幅度不如心脏;伤后1 h或3 h达到最低值.烧伤组大鼠各时相点的大脑血流量与假伤组接近(F=1.812,P值均大于0.05).(3)Lv+dp/dt max和LV-dp/dt max与心肌血流量均呈显著正相关(r值分别为0.651和0.617,t值分别为4.456、4.222,P值均小于0.01). 结论 严重烧伤后极短时间内(伤后10 min)即可发生心肌缺血和心功能下降,心脏血流量迅即减少是心功能变化的重要原因,心肌损害和心功能下降可能是导致其他脏器血流量降低的重要因素之一.

Changes and relations between heart function and organ blood flow in rats at early stage of severe burn

Objective To investigate the instant changes in heart function and organ blood flow,and their relations in rata at early stage of severe burn. Methods Thirty-six SD rats were divided into sham injury group (S, n=6) and burn group (B, n=30) according to the random number table. Rats in B group were subjected to 30% TBSA full-thickness burn. Five time points for observation: 10 and 30 minutes, and 1, 3, and 6 hour (s) post injury (PIM/H) were set up, with 6 rats at each time point. Rats in S group were sham scalded with 37 ℃ warm water. Hemodynamics indexes including heart rate (HR),mean artery pressure (MAP), left ventricular systolic pressure (LVSP), left ventricular end-diastolic pressure (LVEDP), LV ± dp/dt max were determined. Blood flow of heart, brain, kidney, spleen, stomach,and ileum was determined respectively with fluorescent micraspheres method. The correlation between LV ± dp/dt max and myocardial blood flow was analyzed. Results (1) Compared with those of S group,HR in B group decreased gradually after iniury; MAP, LVSP, LV + dp/dt max, LV-dp/dt max and myocardial blood flow in B group decreased obviously at PIM 10 (with F value respectively 12.062, 12.629,11.066, 18.374, 9.468, and P values all below 0.01). Among them, myocardial blood flow decreased from (6.8±0.8) mL·min~(-1)·g~(-1) to (2.6±0.5) mL·min~(-1)·g~(-1). Above-mentioned indexes increased gradually as the time after injury went on, with the highest values (except for LV + dp/dt max) observed at PIH 1, which decreased again later, with values at PIH 3 and 6 significantly lower than those in S group (the same F values as above, P values all below 0.01). There was no obvious difference in LVEDP between S group and B group at each time point (F=1.205, with P values all above 0.05). (2)Compared with those of S group, blood flow of kidney, spleen, stomach, and ileum of rats in B group at P1M 10 declined obviously (with F value respectively 22.694, 20.856, 12.653, 7. 293, P < 0.05 or P < 0.01), but the decline range was smaller than that in heart. The lowest values of above-mentioned indexes were observed at PIH 1 or PIH 3. Brain blood flow of rats in B group at each time point was close to that in S group (F=1.812,with Pvalues all above 0.05). (3) The correlation coefficient r between LV + dp/dt max, LV-dp/dt max and myocardial blood flow was respectively 0.651 and 0.617, showing significant positive correlation (with t value respectively 4.456 and 4.222, and P values all below 0.01). Conclusions The myocardial ischemia and decrease in cardiac function may occur in a very short time after severe burn (PIM 10). The rapid decrease of heart blood flow plays an important role in the change in cardiac function. Myocardial damage and decrease of cardiac function may be one of the important factors result in the decline of blood flow in other organs.