Theoretical personalized optimum chest compression point can be determined using posteroanterior chest radiography

초록

Aim: Cardiopulmonary resuscitation guidelines suggest the lower sternal half be compressed. However, stroke volume has been assumed to be maximized by compressing the 'point' (P_max.LV) beneath which the left ventricle (LV) is at its maximum diameter. Identifying 'personalized' P_max.LV on computed tomography (CT), we derived and validated rules to estimate P_max.LV using posteroanterior chest radiography (chest_PA). Methods: A retrospective, cross-sectional study was performed with non-cardiac arrest (CA) adults who underwent chest_PA and CT within 1h (derivation: validation= 3: 2). On chest_PA, we defined CD (cardiac diameter), RB (distance from right cardiac border to midline) and CH (cardiac height, from carina to uppermost point of left hemi-diaphragm). Setting P_zero (0, 0) at the midpoint of xiphisternal joint and designating leftward and upward directions as positive on x and y axes, we located P_max.LV (x_max.LV, y_max.LV). Mathematically, followings were inferable: x_max.LV = alpha(0)*CD-RB; y_max.LV = beta(0)*CH + gamma(0). (alpha(0): mean of (x_max.LV + RB)/CD; beta(0), gamma(0): representative coefficient and constant of linear regression model, respectively). We investigated their feasibility by applying them to in-hospital (IHCA) and out-of-hospital CA (OHCA) adults. RESULTS: Among 266 (57.6 +/- 16.4 years, 120 females), followings were derived: x_max.LV = 0.664*CD-RB; y_max.LV = 40 - 0.356*CH. Estimated P_max.LV was closer to the reference than other candidates and thus validated: 15 +/- 9 vs 17 +/- 10 (averaged P_max.LV, p = 0.025); 76 +/- 13, 54 +/- 11 and 63 +/- 13 mm (3 equidistant points as per guidelines, all p < 0.001). Among IHCA and OHCA patients, 70.7% (106/150) and 38.0% (57/150) had previous chest_PA with measurable parameters to estimate P_max.LV. CONCLUSION: Personalized P_max.LV, which is potentially superior to the lower sternal half and feasible in CA, is estimable with chest_PA.

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