| [Objective]This study firstly conducted a diagnostic test on exploring the application efficacy of locating the catheter tip in cancer patients with indwelling peripherally inserted central catheter(PICC)with the guidance of intracavitary electrocardiogram(IC-ECG).Then,authenticity,reliability and practicability indexes [e.g.P-wave amplitude on IC-ECG(IP)and the ratio of IP to P-wave amplitude on electrocardiogram(IP/SP)],we aim to establish an overall standard for ECG-guided position of the catheter tip of PICC in cancer patients.[Methods]1.A total of 134 cases of cancer patients with indwelling PICC and requirement for imaging examinations from October 2018 to June 2019 were recruited.Prior to imaging examinations,P-wave morphology differences of surface electrocardiogram(ECG)and IC-ECG after filling with saline solution were compared.Based on the pre-predicted position of the catheter tip of PICC,three conditions(outside superior vena cava(SVC),in the region of the SVC,within the scope of the right atrium(RA)) were determined and compared with the gold standard(X-ray-guided position).Briefly,X-ray-guided location [the lower third part of SVC or the cavo-atrial junction(CAJ)(the most optimal location)] was considered as the standard.Recruited patients were divided based on the pre-predicted location by IC-ECG as follows: group 1:location outside SVC,or the upper third and the middle third part of SVC;group 2:location the lower third part of SVC or the CAJ;group 3: location the RA.SP,IP and IP/SP of each patient were respectively recorded.Receiver operating characteristic(ROC)curves were plotted for assessing the application of IP and IP/SP in predicting the location of the catheter tip of PICC in cancer patients.Cut-off value,specificity,sensitivity,Youden index,positive predictive value(PPV),negative predictive value(NPV)and area under curves(AUC)were analyzed.2.Eligible cancer patients with indwelling PICC(n = 180)were subjected.According to the gold standard of X-ray-guided location,chi-square test was conducted to assess the authenticity indexes(sensitivity,specificity,Youden index,false negative rate,false positive rate,crude agreement rate,positive likelihood ratio and negative likelihood ratio)and reliability indexes(Kappa)and practicability indexes(PPV and NPV)of ECG-guided location of the catheter of PICC.[Results]1.After filling with saline solution to obtain IC-ECG,predicted catheter tip of PICC based on P wave was acquired.Alongside ECG-guided location of the catheter tip of PICC,the accuracy of P-wave morphology on IC-ECG or surface ECG in predicting the location of PICC tip was defined by comparison to the gold standard(X-ray-guided location).Catheter tip confirmed by X-ray showed that 2(1.5%)locating outside SVC;96(71.6%)locating in the region of the SVC,of which 27(20.1%)were located in the upper third part of SVC,31(23.1%)in the middle third part of SVC,38(28.4%)in the lower third part of SVC;29(21.7%)in the CAJ region;and 7(5.2%)within the scope of the RA.There were 8(6.0%)cases with inconsistent locations,including 6 cases where PICC tip was located in RA as X-ray showed and that in SVC as P wave predicted;a total of 1 cases had the condition that PICC tip was in SVC as X-ray located,while P wave predicted that the tip was failed to be inserted in SVC;in addition,there were 1 cases with the X-ray guided location in SVC,whereas P wave predicted the location in RA.Collectively,the accuracy of P-wave morphology on IC-ECG or ECG in predicting the location of PICC tip was up to 94.0%,suggesting a well feasibility.2.By quantifying P wave,SP,IP and IP/SP were recorded.The average IP in group 2were higher than that in group 1(4.51 ± 3.09 m V > 3.51 ± 2.22 m V,P > 0.05)and lower than group 3(4.51 ± 3.09 m V < 6.25 ± 3.60 m V,P < 0.05).In addition,the average IP/SP in group 2 were higher than that in group 1(3.68 ± 2.39 > 2.81 ± 1.34,P > 0.05)and lower than group 3(3.68 ± 2.39 < 5.03 ± 2.99,P < 0.05).3.ROC curves were plotted for assessing the diagnostic potentials of IP and IP/SP.The optimal cut-off values of IP and IP/SP was 3.15 m V ~3.75 m V and 1.65 ~ 3.25,respectively.Based on these values,IP1 = 3.15 m V had a sensitivity of 66.7%,a specificity of 58.6%,a Youden index of 0.25,a PPV of 80.0%,and a NPV of 45.7%,and for the combination of IP2 = 3.75 m V were 50.7%,83.3%,0.34,83.3%,47.6%,respectively.The corresponding values for IP/SP1 = 1.65 were 94.2%,27.6%,0.22,80.0% and 76.2%,and for the combination of IP/SP2 =3.25 were 59.4%,75.0%,0.34,80.0% and 50.0%.The area under ROC curves(AUC)of IP1 was 0.62(95%confidence interval(CI)= 0.50 ~ 0.75)and of IP2 was 0.69(95% CI = 0.58 ~ 0.80).Meanwhile,the AUC of IP/SP1 was 0.62(95% CI = 0.50 ~ 0.75)and of IP/SP2 was0.69(95% CI = 0.59 ~ 0.80).It is suggested that IP and IP/SP could specifically and sensitively locate the catheter tip of PICC in cancer patients.4.Evaluating the authenticity,reliability and practicability of ECG-guided location of PICC tip.Among 180 cases of cancer patients indwelling PICC,161 cases under ECG guidance were confirmed to have the most optimal location of the catheter tip by X-ray,and 19 had non-optimal locations.Relative levels of sensitivity,specificity,Youden index,false negative rate,false positive rate,crude agreement rate,positive likelihood ratio,negative likelihood ratio,Kappa,PPV and NPV were calculated as98.76%,84.21%,0.83,1.24%,15.79%,97.22%,6.25,0.01,0.85(kappa > 0.80),98.15%,and 88.89%,respectively.It is indicated that locating the catheter tip in cancer patients indwelling PICC according to P wave on ECG and the quantified P-wave indexes are feasible and worth of applying in clinical practice.[Conclusion]After filling with saline solution to obtain IC-ECG,P wave morphology and its quantified indexes(IP and IP/SP)are conductive to accurately locate the catheter tip of PICC.The following three conditions predict the most optimal location of PICC tip(in the lower third part of SVC or in the CAJ region):(i)P-wave elevation on IC-ECG higher than surface ECG during the same period;(ii)3.15 m V ? IP ? 3.75 m V;(iii)1.65 ? IP/SP ? 3.25.IC-ECG-guided location of the catheter tip of PICC in cancer patients has massive advantages of simple procedures,no radiation injury and high safety,which is expected to be a novel method applied in clinical practice. |
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