Comparison of Heart Proportions Compressed by Chest Compressions Between Geriatric and Nongeriatric Patients Using Mathematical Methods and Chest Computed Tomography: A Retrospective Study.

Background: Current guidelines recommended that chest compression depths during cardiopulmonary resuscitation (CPR) should be at least one-fifth of the external chest anteriorposterior (AP) diameter. The chest AP diameter increases because of dorsal kyphosis, senile emphysema, and poor lung compliance associated with aging. This study aimed to compare the proportion of the heart compressed by chest compression (based on the ejection fraction [EF]) in geriatric and nongeriatric patients. Methods: We performed a retrospective analysis of the chest computed tomography findings obtained between January 2010 and August 2016 and measured the chest anatomical parameters such as the perpendicular external and internal chest AP diameters with the heart AP diameter. Based on values of these parameters, EFs with 50- and 60-mm depths were obtained. In addition, we investigated and compared the proportion of 50- and 60-mm depths and heart AP to external chest AP diameter between the 2 groups. Results: We randomly selected and analyzed 100 of 1,921 geriatric and 100 of 22,090 nongeriatric populations from a database. The means +/- standard deviations of EFs with 50- and 60-mm depths for geriatric and nongeriatric people were 37.1%+/- 12.1% vs. 43.2%+/- 13.8% and 47.5%+/- 12.8% vs. 54.6%+/- 14.8%, respectively (all p<0.001). The proportion of 50- and 60-mm depths and heart AP to external chest AP diameter were significantly different between the 2 groups (all p<0.05). Conclusion: Chest compression depths based on current guidelines are not sufficient for geriatric patients during CPR, hence, deeper chest compressions would be considered.