The Research About The Accuracy Of Continuous Cardiac Output Monitoring Through Pulse Contour Analysis

Objective: Swan-Ganz the traditional way of cardiac output monitoringwas once treated as the golden standart of hemodynamics determinations. Thismethod helps people determine norms including pulmonary and cardiacvascular pressures and pulmonary vascular by measuring the right heartsystem. Then people can determine the hemodynamics states and body'soxygenation function of critically ill patients. However, in recent years,Swan-Ganz are fading away in clinical treatment because of its complicationsand uncertainty in long-term curative effect. The pulse contour analysiscontributes to earlier awareness of ill changes because it doesn't detect theright heart function, and it can lead to less injure and less complications. Thecatheter places easily and the parameter can be measured repeatedly. It canconstantly measure and record the change of norms including cardiac output.In addition to monitoring heart function and vascular tone, pulse contouranalysis can also monitor norms related to capacity state and etrevoscular lungwater, which serve as a strong basis for clinical guide treatment. So pulsecontour analysis has of high practicality in clinical treatment. Researches haveconfirmed the consistency between the result from pulse contour analysis andthe result from Transpulmonary thermodilution andPulmonary artery catheterization. But when the hemodynamics state changes,the accuracy of pulse contour analysis is still in question.Different irregular interventions, including liquid load tests, operatingNorepinephrine rate, and changing parameters of mechanical ventilation, willaffect vascular compliance and resistance, which are closely related to thepulse contour analysis results. So this study aims to exploit the reliability ofpulse contour analysis results when interventions involved.Methods: Twenty patients who need PICCO in ICU were selected. We record their PCCO value after a regular treatment and before the calibration ofpulse contour analysis. And then we record their PCCO value after theTranspulmonary thermodilution. These interventions include: liquid load tests(300-500ml colloidal or500-1000ml crystal, infusion in30minutes), operatingNorepinephrine rate (0.2±0.1ug/kg/min), operating Dopamine rate (4±2ug/kg/min), and changing parameters of mechanical ventilation(PEEP or PS4±2mmHg). In this study, patients who received calibration within1hourbefore the interventions we won't recalibrate again. If not, we recalibrate themand then record the monitor data. After we apply the regular treatment, werecord the PCCO/CO value before and after the calibration. Then we analysethem with t-test and the limits of the associated agreement described by Blandand Altman to evaluate the reliability of pulse contour analysis.Results: In this clinical experimental study, the related data from20patients were collected, which consist of134groups of cardiac output values.The cardiac output values were collected after therapeutic intervention(including58groups of the liquid load,18groups of adjusting thenorepinephrine rate,14groups of adjusting the dopamine rate, and44groupsof the mechanical ventilation parameters change.)1Comparison between PCCO value before and after the calibration1.1Comparison between PCCO values of rehydration therapy group beforeand after the calibrationAfter the rapid rehydration therapy, the mean±standard deviation of COvalue is6.57±2.30L/min. The mean±standard deviation of PCCO valuebefore calibration is6.88±2.46L/min. And after the calibration it is6.57±2.31L/min. The P value of Comparison between PCCO value before andafter the calibration is less than0.05. So the difference was statisticallysignificant.1.2Comparison between the PCCO values of Mechanical ventilationparameters group before and after calibrationAfter the adjustment of mechanical ventilation parameters, the mean±standard deviation of CO value is6.28±1.89L/min. The mean±standard deviation of PCCO value before calibration is5.98±1.79L/min, and after thecalibration it is6.33±1.97L/min. With the comparison between PCCO valuebefore and after the calibration, we get the P value is less than0.05. So thedifference was statistically significant.1.3Comparison between PCCO value before and after the calibration afternorepinephrine infusion rate adjustment.After raising norepinephrine infusion rate, the CO mean±standarddeviation is7.30±1.38L/min. The mean±standard deviation of PCCO valuebefore calibration is5.49±1.97L/min, and after the calibration it is6.26±2.52L/min. With the comparison between PCCO value before and afterthe calibration, we get the P value is less than0.05. So the difference wasstatistically significant.After Lowering norepinephrine infusion rate, the CO mean±standarddeviation is5.52±1.57L/min. The mean±standard deviation of PCCO valuebefore calibration is5.40±0.84L/min, and after the calibration it is6.17±1.35L/min. With the comparison between PCCO value before and afterthe calibration, we get the P value is less than0.05. So the difference wasstatistically significant.1.4Comparison between PCCO value before and after the calibration afteradjusting the dopamine infusion rate.After raising the dopamine infusion rate, the mean±standard deviationof CO value is6.74±0.95L/min. The mean±standard deviation of PCCOvalue before calibration is4.96±1.07L/min, and after the calibration it is6.89±1.21L/min. We get the P value is less than0.05. So the difference wasstatistically significant.After lowering the dopamine infusion rate, the mean±standard deviationof CO value is2.51±0.42L/min. The mean±standard deviation of PCCOvalue before calibration is1.85±0.23L/min, and after the calibration it is2.52±0.44L/min. We get the P value is less than0.05. So the difference wasstatistically significant.(Fig.3, Table2)2Consistency analysis of PCCO tests and CO tests before the calibration. Consistency analysis of the data of134sets therapeutic intervention, theCO value range is2.0-12.1L/min (the mean value is6.26L/min); the PCCOvalues range before calibration is1.5-13.2L/min (the mean value is6.05L/min), the differences between two methodsis0.21L/min, and the limits ofagreement is-2.35to2.75L/min. So the two methods can be usedinterchangeably within the consistency range (±1.25L/min). The Scatter of thedifference between PCCO values and CO values is in graph4.3Consistency analysis of PCCO tests and CO tests after the calibration.Consistency analysis of the data of134sets therapeutic intervention, theCO value range is2.0-12.1L/min (the mean value is6.26L/min); the PCCOvalues range before calibration is2-11.7L/min (the mean value is6.27L/min),the differences between two methods is-0.01L/min, and the limits ofagreement is-0.39~0.36L/min. So the two methods can be usedinterchangeably within the consistency range (±1.25L/min). The Scatter of thedifference between PCCO values and CO values is in graph5. In addition, therelative error of the PCCO value after the calibration is16%.Conclusion:1The clinical study had shown that pulse contour analysis in cardiac outputmonitoring should be recalibrated if treatment interventions, including liquidload tests, adgusting norepinephrine or dopamine rate, and changingparameters of mechanical ventilation.2Determination of cardiac output by post-intervention pulse contour analysiswas in good consistency with the results from Transpulmonary thermodilutionand clinically acceptable.