Determination of optimal tip position of peripherally inserted central catheters using electrocardiography – a retrospective study

Background: Accurate tip positioning of a peripherally inserted central catheter (PICC) is crucial to ensuring optimal drug delivery and avoiding potential complications. The main objective of this study was to evaluate the amplitude ratios of intravascular ECG (ivECG) and body surface ECG (exECG) when the correct tip position was confirmed by chest X-ray (CXR). Methods: This retrospective study analyzed ivECG, exECG, and CXR of 278 patients who underwent a PICC placement procedure. The tip-to-carina distance (TCD) was measured using vertebral body units (VBU) on CXR, and tip locations were categorized as follows: Zone 1, malposition as TCD <0.8 VBU; Zone 2, suboptimal as 0.8 VBU ≤ TCD < 1.5 VBU; Zone 3, optimal as 1.5 VBU ≤ TCD ≤2.4 VBU; Zone 4, deep as TCD > 2.4 VBU. The amplitude ratios between ivECG and exECG and within ivECG of the corresponding waves were calculated and compared in each Zone. Results: The ivECG/exECG amplitude ratios of P-wave (P iv /P ex ) and QRS-complex (QR iv /QR ex and RS iv /RS ex ) in Zone 3 were significantly higher than in Zones 1 and 2 (adjusted P<0.05). The amplitude ratios of the P-wave and QRS-complex of the ivECG (P iv /QR iv and P iv /RS iv ) were significantly lower in Zone 3 than in Zones 1 and 2 (adjusted P<0.001). The calculated TCD using stepwise multiple regression analysis was estimated to be 1.121 + 0.078 × P iv /P ex – 0.172 × P iv /QR iv . Conclusions: The amplitude ratios between ivECG and exECG and within ivECG (P iv /P ex and P iv /QR iv ) can help determine catheter tip positioning during the PICC catheterization procedure. However, caution is required for accurate positioning of the PICC tip.