Right cardiac border to cardiac diameter (RB:CD) ratio, a simple radiological index associated with a good neurological outcome

Choi, Himchan; Chon, Sung-Bin; Yoo, Seung Min; Kim, Hyoungouk

J Korean Soc Emerg Med > Volume 32(6); 2021 > Article

Original Article

Journal of The Korean Society of Emergency Medicine 2021;32(6): 493-508.

Right cardiac border to cardiac diameter (RB:CD) ratio, a simple radiological index associated with a good neurological outcome

¹Department of Emergency Medicine, CHA Bundang Medical Center, CHA University School of Medicine, Seongnam, Korea
²Department of Diagnostic Radiology, CHA Bundang Medical Center, CHA University School of Medicine, Seongnam, Korea

Correspondence

Sung-Bin Chon ,Tel: 031-780-1904, Fax: 031-780-6125, Email: 1tim4ezra7@gmail.com,

Received: August 5, 2020; Revised: September 21, 2020 Accepted: October 13, 2020. Published online: December 31, 2021.

ABSTRACT

Objective:
The optimum chest compression point during cardiopulmonary resuscitation (CPR) associated with a good neurological outcome is unestablished. We aimed to suggest the association between the point and a simple index measured on anteroposterior chest radiography (chest_AP).
Method:
This retrospective, cross-sectional study included all adults with available chest_AP who arrived at a university hospital from January 2014 to June 2019 for non-traumatic out-of-hospital cardiac arrest (OHCA). Distances from the vertical midsternum to the farthest right and left cardiac borders were defined as RB and LB, respectively. Their sum provided cardiac diameter (CD). Assuming the universality of cardiac anatomy, the cardiac structure immediately beneath the midsternum was compressed most forcefully during CPR. The influencing outcome of CPR was determined using the RB:CD ratio. We investigated the association of RB:CD ratio with a good neurological outcome at discharge using multiple logistic regression analysis, adjusting for the core Utstein elements and comorbidities.
Results:
Among 429 patients (63.2±14.5 years; 121 [28.2%] female), return of spontaneous circulation, survival-to-discharge and good neurological outcome at discharge were achieved in 259 (60.4%), 121 (28.2%) and 84 (19.6%) cases, respectively. The RB:CD ratio (0.279±0.072) was divided into semi-tertiles to enhance clinical usage: <0.25 (n=149, reference), 0.25-0.30 (n=119) and >0.30 (n=161). The second group was associated with good neurological outcome (odds ratio, 6.00 [95% confidence interval, 1.58-22.8], P=0.010).
Conclusion:
An RB:CD ratio of 0.25-0.30 measured on chest_AP is associated with good neurological outcomes in OHCA victims receiving CPR.

Key words: Cardiopulmonary resuscitation; Heart ventricles; Radiography, Thoracic; Treatment outcome