Studyof Intracavityelectrocardiography P Wave Ratioin Preterm Infants PICC Tip Placement

Objective To investigate the P-wave ratio of accurate ECG electrocardiogram?ECG?positioning in preterm infants,that is the ratio of P-wave amplitude to QRS-wave amplitude,and to analyze the effect of body position change on the P-wave ratio.To providea reference for the accurate positioning of PICC and providea basis for the accurate maintenance of PICC in preterm infants.Methods A total of 289 preterm infants who were admitted to the neonatal care unit of a tertiary Class A hospital from January 2018 to March 2019 and met the PICC catheterization indication were taken as the research objects.During PICC puncture,the ECG monitor is used to position the tip of the catheter.After the catheter is placed to the predicted length,the P wave ratio at position 2?natural position?is obtained during the intracardiac ECG positioning,and then the child's limb is placed in the position 1.Keep the catheter insertion length unchanged,and obtain P wave ratio at position 1.Position 1 is:the upper limb abduction and the trunk are 90 degrees when the upper limb is punctured;the lower limb is straightened when the lower limb is punctured;the head and neck are flexed on the puncture side when the head is punctured.Position 2 means that the upper limb is retracted into the trunk at an angle of less than 45 degrees when the upper limb is punctured;the lower limb abduction and the trunk centerline are about 45 degrees when the lower limb is punctured,and the limb is naturally flexed;the head is centered when the head is punctured.After the PICC was placed,a chest X-ray was taken at position 2.Calculate the proportion of P waves in the two positions and mark the level of the thoracic vertebra corresponding to the catheter tip on the chest X-ray.Investigate the difference of P wave ratio in different body positions,find the corresponding relationship between P wave ratio and thoracic spine in the same body position,find the concentration range of 95%of P wave ratio at the tip of the catheter at T₄-T₆,and determine accuracy,sensitivity and specificity of the P wave ratio for positioning the catheter tip position in preterm infants.Results289 cases were included,and 261 cases had characteristic P waves,among the261 cases with characteristic P waves,229 cases appeared in the upper limbs and 32cases appeared in the lower limbs.Transthoracic X-ray positioning catheter tip at T₄?18 cases,6.90%?,T₅?132 cases,50.50%?,T₆?77 cases,29.50%?,T₇?2 cases,0.80%?,T₈?24 cases,9.20%?,T₉?8 cases,3.10%?.229 catheter tips were in the superior vena cava,and the frequency distribution of P waves ratio was as follows:P wave ratios were 0.40 to 0.50?16 cases,6.90%?,0.51 to 0.60?49 cases,21.40%?,0.61 to 0.70?111cases,48.50%?,0.71 to 0.80?47 cases,20.60%?,>0.80?6 cases,2.60%?,the ratio of P waves is concentrated in the 0.61 to 0.70,with an average of 0.65±0.08.When the catheter tip is at the optimal position T₄to T₆,the 95%CI of the P wave is 0.64 to 0.67.When the PICC was inserted through the basilic vein,the median elbow,the axillary vein,the cephalic vein,and the superficial temporal vein,there was a statistically significant difference in the ratio of P waves between the two positions?P<0.01?.The PICC was placed through the saphenous vein of the lower limb,there was no significant difference in the raitio of P waves between the two positions?P=0.082?.The P wave ratio had a significant effect on the position of the catheter tip?P=0.018?.The sensitivity and specificity of intraluminal ECG positioning were 94.9%and 100.0%,and the AUC area is 0.937.Conclusions The intracavityelectrocardiography P wave ratio inpreterm infants PICC tip precise placement has high accuracy,sensitivity,and specificity.The AUG is greater than 0.90,which can become a new method for positioning the PICC catheter tip in preterm infants.When the characteristic P wave ratio is between 0.64 and 0.67,the tip of the PICC catheter ishigh possible to be in the optimal position T₄to T₆.Body position changes affect the P wave ratio of the ECG location in the preterm infants PICC.