| Objective:To analyze the correlation of descending aortal blood pressure(BP*)which could be figured out of the feature parameters of the signal waves extracted from transesophageal descending aortal pulse signal by using a regression equation obtained by previous research and invasive femoral arterial blood pressure(BP) in the progress of acute blood loss in dogs. The signal and invasive blood pressure were measured simultaneously. In the research, credibility of application of reflective photoelectric sensor invented by previous research in the dynamic progress of hemodynamics was demonstrated.Methods:1 Transducers were inserted into the midpiece esophagus after thoracotomy, and the emission site of light source was towards the descending aorta recording the optical signal. Arterial ducts were placed respectively into left femoral artery for bloodletting and right femoral artery for measuring blood pressure. The optical signal and invasive blood pressure were recorded simultaneously by four-channel electrophysiolograph.2 To establish an acute hemorrhage model by bloodletting with the speed of 2.0-2.5ml/Kg-min.3 From the feature parameters(k,s,h/H,H,h,g,At,g/H) obtained from 40 segments of arterial pulse waves selected randomly during acute hemorrhage, blood pressure can be figured out by using a regression equation.4 To verify the accuracy of the descending aortal blood pressure, BP and BP* were compared calculating (?)±s of the absolute value of the difference. And after simple regression analysis, the correlation between them was found by calculating correlation coefficient.5 The level of agreement between BP* and BP were calculated using the between-mathod differerces analysis outlined by Bland&Altman.Results:1 Transesophageal descending aortal pulse wave can be obtained when the blood loss was less than 30% total blood volume.2 The 82.27% waves (26880/32690) were stable, and the pulse waves could be seen rising and falling with respiration.3 When the blood loss was more than 30% total blood volume, only regular respiratory wave rather than pulse wave could be obtained.4 When the blood loss was less than 30% total blood volume, feature parameters were analyzed entered into a regression equation to calculate descending aortic systolic pressure (SBP*), diastolic blood pressure (DBP*) and mean blood pressure (MAP*).5The difference between BP* and BP was fluctuating, The maximum deviation between SBP and SBP, DBP与DBP*, MAP与MAP* were respectively 1.022±0.598mmHg,0.924±0.790mmHg,0.925±0.668mmHg.6 BP* and BP are in good correlation, The correlation coefficients of SBP* with SBP is 0.799 (0.662-0.899), DBP* with DBP is 0.795 (0.702-0.892), MAP* with MAP is 0.814 (0.720-0.897).6 Bland&Altman plot for the difference between BP and BP* values against their mean. Conclusion1 The pulse wave in descending aorta can be obtained transesophageally with reflective photoelectric sensor in the progress of acute blood loss.2 Character parameters can be extracted from the pulse wave, and these parameters attribute to calculate the blood pressure when the blood loss was less than 30% total blood volume by a regression equation established by previous research to support the test of monitoring noninvasive blood pressure through esophagus.3 BP* (calculated from transesophageal descending aortal pulse waves recorded by a reflective photoelectric sensor correlated well with BP(invasive femoral arterial blood pressure) (r≈0.8).4 The blood pressure obtained from the optical signal is fairly accuracy when the blood loss is less than 30% total blood volume. When the blood loss is more than 30% total blood volume, the sensitivity of the sensor is not good enough, and more and further research needed to overcome the situation.5 New monitoring site is found to develop new monitoring equipments for blood pressure. |
PDF Full Text Request