Study On Methods Of Measuring The Length Of PICC To Be Inserted

[Obectives]To analysis the accuracy of the length of PICC placement by 21 measurement methods and explore the related factors which influence the measurement accuracy of the length of PICC placement, in order to make out a more accurate measurement method of the length of PICC placement.[Methods]According to a large number of domestic and abroad literatures, the human anatomical knowledge and the clinical experiences, then we consulted the specialists, and made sure nine suspicious factors those influence the measurement accuracy of length of PICC placement, including height, weight, subcutaneous fat thickness, arm circumference, foot length, the distance from sternoclavicular joint to the right superior heart border, the width of second costal rib, and the width of third costal rib. And we made a set of (21) measurement methods of the length of PICC placement according to the body surface marks. A epidemiology quasi-experiment design was conducted among the convenient sample of 212 tumor patients placed PICC enrolled from Tianjin medical university cancer institute and hospital during October 2009 to August 2010. We analyzed the collected data by SPSS 16.0 statistic software, described all variables'distribution by x±S, analyzed the relationship between 21 measurement differences and 8 suspicious factors by linear regression analysis if all measurement difference'variances are larger than 1.0cm, and then got 21 regression equations. At last, we made some compares among 21 measurements and 21 regression equations, and then made sure a more accurate and simpler measurement.[Results]1. Among 212 cases,29.0% of the left PICC tips and 31.1% of right ones were positioned literally in the lower third of the SVC.2. The variances of differences between the length measured by 21 measurements and the best length are 2.00cm to 2.23cm of the left and 2.17cm to 2.45cm of the right.3. The distance from sternoclavicular joint to the right superior heart border is very related to the differences between the length measured by 21 measurements and the best placement length, which can explain the variances by 46.7%-62.2% of the left and 57.3%-78.9% of the right.4. Some in the other suspicious factors are related to the differences between the length measured by 21 measurements and the best placement length, but the Correlation Coefficient is low, and none of them was enrolled in regression equations.5. If the forecasted length by regression equations including L were the placed length, there were 46.2%-55.9% of the left and 55.5%-73.9% of the right sample'PICC tip position veritably in the atriocaval junction when the allowable error is 1.Ocm, and the variances of forecasted differences were 1.30 cm tol.62 cm of the left and 0.95 cm to 1.37cm of the right.6. Comparing among 21 measurements, the fifth measurement is the simplest method in all.7. If the equations of B1=V+0.7L-1.0cm and Br=V+0.7L+1.5cm were the measured strategies of the length of PICC placement, there were 48(51.6%, left) and 81(68.1%, ringt) cases'PICC tip position respectively in the atriocaval junction when the allowable error is 1.0cm.[Conclusion]1. The measurement accuracies of 21 methods measuring the length of PICC placement all are low,2. The measurement accuracies are mainly related to the distance between sternoclavicular joint and the right superior heart border.3. The best measurement methods are B1=V+0.7L-1.0cm of the left and Br=V+0.7L+1.5cm of the right.