Comparison of optimal point on the sternum for chest compression between obese and normal weight individuals with respect to body mass index, using computer tomography: A retrospective study

Background: Abdominal fatty tissue deposition in obese individuals could alter the proper hand position for chest compression during cardiopulmonary resuscitation, similar to that in pregnant women. This study aimed to identify the difference in body mass index between obese and normal weight individuals by measuring the optimal point of maximal left ventricular diameter (OP^LV), using computed tomography (CT).

Methods: We performed a retrospective analysis of chest CT scans between January 2012 and August 2016 and measured the sternal length and OP^LV and estimated the ratio of OP^LV to that individual sternal length. We also investigated whether OP^LV was within the clinically relevant range of 20 mm to the position advised by the Guidelines 2015. We compared these outcomes between the two groups.

Results: We randomly selected and analysed 50 of 7229 normal weight and 50 of 394 obese individuals from a database. The mean ± standard deviation of the ratio of OP^LV was 22.0 ± 5.7% and 14.8 ± 6.6% of the sternal length, as measured from its most caudal point, respectively, for the obese and normal weight groups (p < 0.001). Both are more caudal than at the middle point of "the lower half of the sternum" as currently recommended. Notably, 96% of the OP^LV in the obese group was within ±20 mm of the guideline point versus 52% for normal weight group.

Conclusion: OP^LV on the sternum in obese individuals was more cranial than that in normal weight individuals. The optimal point for chest compression in obese individuals could be slightly more cranial than that in the others.