Methodological Study On The Measurement Of Intra-abdominal Pressure

Objectives:1.To investigate the effect of different reference transducer positions on intra-abdominal pressure(IAP)measurement in critically ill patients.2.To explore the effect of different head of bed elevation(HOB)on IAP measurement.Methods:1.A total of 31 patients in ICU from a tertiary referral center in Shandong Province in need of measuring IAP were studied.The period was from October 1,2015 to January 1,2016.We used indirect and direct methods to measure IAP.In each patient,three sets of IAP measurements were measured in the supine position,using the different reference levels and kept as IAPmidax?IAPpubis?IAPphlebostatic.SPSS 19.0 and MedCalc were performed to analysis the data,including descriptive analysis,Pearson correlation analysis,paired t test and Bland-Altman statistics.2.In this study,48 patients were selected as the research objects who were admitted to the ICU form a tertiary referral center in Shandong Province between March 1,2016 and July 1,2016.Each patient was performed IAP measurement every six hours apart in three different positions(supine,15°,30°),and the measurement order was random.Explore the effect of different HOB on IAP measurement and establish the predictive relationship between HOB and supine position.SPSS 19.0 was performed to analysis the data,including descriptive analysis,Repeated measures analysis of variance and Least significant difference for post hoc analysis.Results:1.A total of 612 measurements were made in the study,of which 306 were measured directly and 306 were measured indirectly.Performing the symphysis pubis position,the correction between direct method(9.82±4.01 mmHg)and indirect method(8.77±4.48 mmHg)is 0.967(P<0.05),the difference is statistically significant(P<0.05).Performing the midaxillary level position,the correction between direct method(11.74±4.71 mmHg)and indirect method(11.65±4.63 mmHg)is 0.972(P>0.05),the difference is not statistically significant(P<0.05).Performing the phlebostatic position,the correction between direct method(10.98±4.65 mmHg)and indirect method(10.38±4.75 mmHg)is 0.970(P<0.05),the difference is statistically significant(P>0.05).The calculated bias between lAPmidax and IAPpubis is 2.9mmHg,95%agreement of limits is(-0.8?6.5)mmHg,upper limit of-0.8,low limit of 6.5.The calculated bias between IAPmidax and IAPphlebostatic is 1.3mmHg,95%agreement of limits is(-1.4?4.0)mmHg,upper limit of-1.4,,low limit of4.0.2.A total of 48 ICU patients eligible for admission were enrolled in the study.Repeated measurements were performed.Time had a significant effect on the results(F = 9.634,P<0.05),and the HOB also had a significant effect on the results(F=5.766,P<0.05).But there was no interaction between time and HOB(F= 0.306,P>0.05).HOB of 15°showed slight difference(P>0.05),whereas that of 30°showed clinically significant difference at four measurement points(P<0.05).The difference of IAP between HOB of 15°,30° and supine position is(1.15?2.10 mmHg)and(3.69?3.88 mmHg).Conclusions:1.We should use midaxillary level as the reference transducer position.2.The symphysis pubis or phlebostatic axis reference lines are not interchangeable with the midaxillary level through the intra-abdominal pressure measurement.3.HOB of 15° showed slight difference,whereas that of 300° showed clinically significant difference at four measurement points.There is a positive correlation between the HOB and the elevation of the IAP.4.when the patients is raised form supine to HOB 30°,the IAP is increased 1 level,approximately 4 mmHg,the difference between supine and HOB of 30° is about 2 mmHg.5.Nurses should put the patients in the actual position in the IAP measurement.