Depth Of a central venous catheter tiplength of insertionguidelinefor pediatric patients

MethodsThe Ethics Committee of Seoul National University Hospital approved the study protocol,and informed parental consent was obtained in all cases.Over a 6-month period,pediatric patients scheduled for congenital heart surgery were enrolled.Patients with any extra cardiac vascular or rotational abnormality were excluded.In this study,an anterior approach to the right internal jugular vein was used.The puncture site was located medial to the sternal head of the sterno-cleidomastiod muscle,between the apex of the tri-angle and the cricoid cartilage and lateral to the carotid artery.The CVC insertion technique and the manner in which we verified catheter tips are described in our previous study (12).After advan-cing the tip of a CVC to the SVC—RA junction,under TEE monitoring,a nurse blinded to the experiment measured the length of the CVC beneath the skin using the depth indicator on the CVC.Information on patient height,age,and weight were also collected.Scatter plots of distance from skin to the SVC/RA junction and age,height and weight were made,and the linearities of these rela-tionships were examined using correlation analysis.Multiple linear regression analysis was also per-formed to identify factors capable of predicting the distance from the skin to the SVC/RA junction.Statistical significance was accepted for P -values <0.05.Statistical analyzes were performed using Sigma plot 2000and SPSS version 10.0(SPSS Inc.,Chicago,IL).ResultsA total of 60CVC cannulations were studied.Patient’s demographic characteristics are listed in Table 1.Age,height,and weight are presented as median (minimum Àmaximum)because these dis-tributions were skewed to the right.On the first post-operative chest radiograph,none of the cathe-ter tips were in the right atrium.The distance from the skin puncture site to the SVC—RA junction was more correlated with patient height (r ¼0.81)than weight (r ¼0.76)or age (r ¼0.60).Using multiple regression analysis,after adjusting for the other two variables,only patient height was significantly correlated with the distance from the skin puncture site to the SVC—RA ing a simple regression model,the lower 95%prediction interval with each patient height was obtained.A straight line was then constructed using the minimum and maximum values of the lower pre-diction limit (Fig.1).The prediction interval provides a method of predicting individual values for distance to the SVC—RA junction,whereas the confidence interval of the mean provides those of the predicted mean value.The resulting equation was:Initial length of insertion ðcm Þ¼1:7þ½0:07Âheight ðcm Þ :This formula predicts a CVC tip positioning above the RA junction at least 97.5%of the ing this equation,58CVC tips in 60patients were above the SVC—RA junction.The other two were within 1cm of the SVC—RA junction (Fig.1).DiscussionTo our knowledge,this is the second report concern-ing the depth of CVC insertion in pediatric patients.Before Andropoulos et al.(7)proposed the formula—Table 1Demographic characteristics of the study subjects Variables Median (minimum,maximum)Age (month)13.5(1.0,173.0)Height (cm)80.8(56.0,160.0)Weight (kg)10.6(4.2,46.2)Values represented are median (minimum,maximum).16141210864406080100120140160180Height (cm)D i s t a n c e f r o m s k i n t o S V C –R A J u n c t i o n (c m )Fig.1.Scatter plot of patient heights vs.distance from the catheter insertion site to the junction of the superior vena cava (SVC)and the right atrium (RA)for a right internal jugular vein (IJV)ing a simple regression model,the lower 95%predic-tion interval with each patient height was obtained.A straight line was then constructed using minimum and maximum values of the prediction lower limits.S.Z.Yoon et al.356(height in cm/10)À1for patients100cm in height,and(height in cm/10)À2for patients !100cm for correct positioning of an inserted CVC tip in pediatric patients—the length of inser-tion was decided based on personal experience for most anesthesiologists(13).For a90-cm tall patient, the length of insertion is8cm using the formula of Andropoulos et al.,which compares to8.9cm using our formula.For a110-cm tall patient,the length of insertion is9cm using Andropoulos’et al.formula, but9.4cm using our formula.These differences may be explained by the fact that they used chest radiography to identify the SVC—RA junction.With regard to the study by Aslamy et al.(9),a consider-able portion of CVC tips which were in the cardiac silhouette on the chest radiograph may have actu-ally been positioned in the SVC.Thus,the guide-lines proposed by Andropoulos et al.(7)for CVC placement can lead to an unintentional placement of a catheter tip in the mid-SVC away from the SVC —RA junction,which may cause suboptimal catheter performance.Our study has some limitations.Our formula for initial CVC insertion only applies to an anterior approach to the internal jugular vein(IJV)not to a lower approach to the IJV or subclavian vein,and our formula has not been validated for children below40or above140cm.In conclusion,our proposed formula can be used to position the catheter tip close to the right atrium and prevent unintentional placement of the cathe-ter tip into the atrium in the studied patient population.AcknowledgementsThis article was supported from departmental sources and the study was performed at Seoul National University Hospital. 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