| Objective:Based on the chest X-ray location as the gold standard,the relationship between the right atrial microbubble density grading of the modified microbubble test and the tip location of PICC was analyzed.By calculating the specificity and sensitivity of the modified microbubble test to identify the PICC tip,a method that can save time and cost,accurate and noninvasive PICC tip positioning is explored.Methods:This study is a diagnostic study with a convenience sampling,choosing patients which were hospitalized in PICC outpatient department and ICU in the First Affiliated Hospital of NanChang University from August 2017 to February 2018.The patients under PICC guided by ultrasound were selected as research subjects.All patients were followed up by ultrasound guided PICC catheter placement,modified microbubble test and chest X ray localization.The right atrium microbubble density was observed from the apical 4-chambers and subcostal long-axis view.It was divided into three grades: I,massive microbubbles;Ⅱ,few microbubbles,and III,no microbubbles.Chest X-ray positioning is the gold standard.It is divided into position(ideal position)and non position(non ideal location,malposition).An unclear transthoracic echocardiogr 4-chambers section,the chest X-ray,not repaired cardiac shunting,and the pregnant women were excluded.Chi square test and variance analysis were applied to compare the clinical data of three groups of patients with different PICC tip positions.Chi square test and contingency coefficient C were used to analyze the relationship between the density of microbubbles and the location of PICC tip.There may be four corresponding relationships between the chest X ray location method and the modified microbubble test.First,the two methods confirm that the catheter tip is located in position;Second,the two methods suggest that the tip of the catheter is not in position;Third,Chest X-ray showed that the tip of the catheter was not in place,and the modified microbubble test was in place.Fourth,Chest X-ray showed that the tip of the catheter was not in position,while the modified microbubble test showed no in place.Based on the above relationship,the sensitivity and specificity of PICC tip position were evaluated by the modified microbubble test.Results:1.In 120 PICC patients,2 cases refused to participate in this study,3 cases of right atrium ultrasound is not clear,2 cases of conscious intolerance,5 cases of chest X ray are not clear.Finally,108 patients were implemented the modified microbubble test and chest X-ray.2.According to the chest X-ray localization results of 108 patients,69(63.9%)were ideal locations,33(30.6%)were non ideal position,6(5.5%)were malposition.There was no significant difference in clinical data between the three groups(P > 0.05),which was comparable.3.In the modified microbubble test,there were grade I microbubble 74(68.5%),gradeⅡmicrobubble 25(23.2%)and grade Ⅲ 9(8.3%).Among grade I microbubble,2 in the right atrium could also see bright color lines in the right atrium.4.There was a correlation between microbubble density and the tip position of the catheter,showing a moderate intensity correlation,and the contingency coefficient=0.632.The patients with the ideal position of the tip position in the grade I microbubbles accounted for 90.5%,the ideal position of the second grade microbubbles was 8%,the difference was statistically significant(P < 0.0125),the heterotopic rate in the grade I microbubbles was 0%,and the difference was 60% in the stage III microbubbles(P < 0.0125);the non ideal position of the second grade microbubbles was 88%,and the third grade microbubbles were not ideal.The location was 66.7%,and the difference in tip position was not statistically significant,P=0.111.5.Of the 108 patients,69 PICC catheter tip were located in position(ideal position),non positional(non ideal position,malposition)in 39 were determined by chest X ray.In the modified microbubble test,70 cases of PICC were in position(ideal position)and 38 cases were not in position(non ideal position,malposition).The sensitivity of the PICC tip in place was 95.7%(66/69),the specificity was 89.7%(35/39),the rate of missed diagnosis was 4.4%(3/69),the misdiagnosis rate was 10.3%(4/39),the positive predictive value was 94.3%(66/70),the negative predictive value was 92.1%(35/38),and the Youden index was 0.85.The consistency between the two methods is good,and the Kappa value is 0.86.Conclusion:1.In the modified microbubble test,the right atrium should be used to obtain from apical 4-chambers and subcostal long-axis view,and it should be fully expanded in four chambers,especially the right atrium,and the tricuspid valve should be clearly shown as the best observation.2.The microbubble density in the modified microbubble test was correlated with the position of PICC tip,and it was related to the middle intensity.The specific relationship was:(1)grade I microbubbles: ideal position;(2)grade I microbubbles and white bright color lines: right atrium;(3)gradeⅡ,Ⅲ: non ideal position or the tip enters the other veins.3.Compared with the chest X-ray localization method,the modified microbubble test method has high sensitivity and specificity in identifying PICC in the position,and the operation is simple,noninvasive,less time and low cost.4.The modified microbubble test can be used as a screening test for PICC tip position.When there are technical limitations or suspicious patient,further chest X-ray is necessary. |
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