Abstract: Objective: To investigate P-wave ratio of the ECG-aided tip accurate localization and the effect of body position change on P-wave ratio of PICC cavity electrograph in premature infants. Methods: 289 premature infants who were admitted to the neonatal intensive care unit of a hospital in Bengbu from January 2018 to March 2019 and met the indications of PICC catheterization were selected as the research subjects. After placement the catheter, the child’s limb was placed in position 1 and position 2 (natural position) respectively to receive ECG-aided tip localization. Chest X-ray was taken at the position 2 after fix the PICC. The ratio of P-wave in the ECG at the two positions was compared, and the relationship between the P-wave ratio and the tip position was studied at position 2. Results: When the PICC was placed in the basilica vein, elbow median vein, iliac vein, cephalic vein, and superficial vein, the difference in the P-wave ratio of the ECG in the two positions was statistically significant (P<0.01). The 95% confidence interval for P-wave ratio was 0.64-0.67 when the tip of PICC catheter was at T4-T6. The sensitivity and specificity of the ECG-aided tip localization were 94.9% and 100.0%. Conclusion: The ECG-aided tip localization in premature infants has high sensitivity and specificity. When the P-wave ratio is between 0.64-0.67, the tip of PICC catheter is 95% likely to be in the best position. The position change is the influence factor of the inner electrogram positioning of PICC cavity in premature infants.

Key words: electrocardiography; P-wave ratio; Peripherally Inserted Central Catheter; premature infants