No abstract

Objective There is a traditional assumption that to maximize stroke volume, the point beneath which the left ventricle (LV) is at its maximum diameter (P_max.LV) should be compressed. Thus, we aimed to derive and validate rules to estimate P_max.LV using anteroposterior chest radiography (chest_AP), which is performed for critically ill patients urgently needing determination of their personalized P_max.LV. Methods A retrospective, cross-sectional study was performed with non-cardiac arrest adults who underwent chest_AP within 1 hour of computed tomography (derivation:validation = 3:2). On chest_AP, we defined cardiac diameter (CD), distance from right cardiac border to midline (RB), and cardiac height (CH) from the carina to the uppermost point of left hemi-diaphragm. Setting point zero (0, 0) at the midpoint of the 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). The coefficients of the following mathematically inferred rules were sought: x_max.LV = α0*CD-RB; y_max.LV = β0*CH+γ0 (α0: mean of [x_max.LV+RB]/CD; β0, γ0: representative coefficient and constant of linear regression model, respectively). Results Among 360 cases (52.0 ± 18.3 years, 102 females), we derived: x_max.LV = 0.643*CD-RB and y_max.LV = 55-0.390*CH. This estimated P_max.LV (19 ± 11 mm) was as close as the averaged P_max.LV (19 ± 11 mm, P = 0.13) and closer than the three equidistant points representing the current guidelines (67± 13, 56± 10, and 77± 17 mm; all P < 0.001) to the reference identified on computed tomography. Thus, our findings were validated. Conclusion Personalized P_max.LV can be estimated using chest_AP. Further studies with actual cardiac arrest victims are needed to verify the safety and effectiveness of the rule.

No abstract