# Reassessing chest compression sites in pediatric cardiopulmonary resuscitation without ventilatory support using echocardiographic assessment: a prospective observational study

## TL;DR

This study uses echocardiography to show that heart position in children changes with breathing, suggesting current CPR guidelines may need updating.

## Contribution

The study provides new evidence that heart position shifts upward during expiration in children, challenging traditional CPR compression site recommendations.

## Key findings

- At end-expiration, the left ventricle was commonly located at the first upper intercostal space in children.
- Heart position shifted upward significantly during expiration compared to inspiration, independent of age, sex, or weight.
- Only a small percentage of children had the left ventricle located at or below the first lower intercostal space during expiration.

## Abstract

The recommended chest compression site during pediatric cardiopulmonary resuscitation (CPR) is based on studies that did not account for dynamic respiratory changes in cardiac position. Since cardiac position changes with respiratory phase, the optimal site during CPR without respiratory support, which physiologically corresponds to the end-expiration state, may differ. We assessed heart position at end-expiration using echocardiography. A prospective observational study was conducted in 18 children under 7 years of age. Transthoracic echocardiography was performed to identify the position of the left ventricle during both inspiration and expiration. Each subject underwent five measurements in each respiratory phase. The position of the left ventricle was recorded relative to the inter-nipple line and categorized by intercostal space (ICS). At end-expiration, the left ventricle was commonly located at the first upper ICS (53.3%) and nipple line (27.8%), with only 4.4% located at the first lower ICS and none below that level. During inspiration, the left ventricle was located at the first lower ICS (50.0%) and nipple line (35.6%). Linear mixed-effects regression demonstrated a significant upward shift in heart position during expiration compared to inspiration (β = -1.46; 95% CI, -1.91 to -1.00; p < 0.001), independent of age, sex, and weight. These findings confirm that respiratory phase affects heart position in young children, with expiration associated with consistent cephalad shift. Therefore, the optimal chest compression site during pediatric CPR without respiratory support may be more cephalad than current guideline recommendations, suggesting the need to re-evaluate traditional landmarks in light of physiologic cardiac motion.

The online version contains supplementary material available at 10.1038/s41598-025-22823-4.