Left of sternum compressions are associated with higher systolic blood pressure than lower half of sternum compressions in cardiac arrest

Introduction: Limited evidence supports guidelines to perform chest compressions at the lower half of the sternum. Imaging studies suggest this location may obstruct blood flow. Our primary aim was to compare the highest arterial line systolic blood pressure (SBP) during lower-half-of-sternum chest compressions (CC) versus those left-of-sternum, where the left ventricle is more likely located. Secondarily, we compared the highest end-tidal CO₂ (ETCO₂).

Methods: We conducted a retrospective cohort study of video-recorded, adult Emergency Department (ED) cardiac arrest resuscitations where changes in CC location were attempted to improve physiologic parameters (SBP, ETCO₂). We excluded epigastric and right-of-sternum compressions. Four CC zones were analyzed: recommended lower-half-of-sternum; left of lower-half-of-sternum; high left lateral; low left lateral. We combined all left-of-sternum compressions for analysis using linear mixed-effects models and multivariable mixed-effects controlling for manual vs. mechanical CCs.

Results: Among 24 patients analyzed, 20 (83.3 %) had initial compressions at the lower-half-of-sternum. 11 patients had 28 lower-half-of-sternum and 32 left-of-sternum CC intervals with available SBPs. In the mixed-effects model, least squares mean (LSMean) SBP was higher with left-of-sternum CCs (108.5 mmHg [95 % CI 88.3-128.8 mmHg]) versus lower-half-of-sternum CCs (66.7 mmHg [95 % CI 46.5-86.9 mmHg], p < 0.001). 18 patients had 44 lower-half-of-sternum and 32 left-of-sternum CC intervals with available ETCO₂. In the mixed-effects model, LSMean ETCO₂ was similar at the lower-half-of-sternum (20.4 mmHg [95 % CI 16.0-24.9 mmHg]) and left-of-sternum (22.6 mmHg [95 % CI 17.6-27.6 mmHg], p = 0.300). Results were similar when controlling for manual vs. mechanical CCs.

Conclusions: In our pilot, retrospective, observational study of select ED cardiac arrest patients, left-of-sternum chest compressions are associated with higher SBP than lower-half-of-sternum compressions, while ETCO₂ was similar.