The correlation between the first heart sound and cardiac output as measured by using digital esophageal stethoscope under anaesthesia.
OBJECTIVE
The use of an esophageal stethoscope is a basic heart sounds monitoring procedure performed in patients under general anesthesia. As the size of the first heart sound can express the left ventricle function, its correlation with cardiac output should be investigated. The aim of this study was to investigate the effects of cardiac output (CO) on the first heart sound (S1) amplitude. Methods : Six male beagles were chosen. The S1 was obtained with the newly developed esophageal stethoscope system. CO was measured using NICOM, a non-invasive CO measuring device. Ephedrine and beta blockers were administered to the subjects to compare changes in figures, and the change from using an inhalation anesthetic was also compared.


RESULTS
The S1 amplitude displayed positive correlation with the change rate of CO (r = 0.935, p < 0.001). The heart rate measured using the esophageal stethoscope and ECG showed considerably close figures through the Bland-Altman plot and showed a high positive correlation (r = 0.988, p < 0,001).


CONCLUSIONS
In beagles, the amplitude of S1 had a significant correlation with changes in CO in a variety of situations.
Young Duck Shin, Department of Anesthesiology and Pain Medicine, Chungbuk National University Hospital, Korea.
Young
Y
Duck Shin
Kyoung Hoon Yim, Department of Anesthesiology and Pain Medicine, Chungbuk National University Hospital, Korea.
Kyoung
K
Hoon Yim
Sang Hi Park, Department of Anesthesiology and Pain Medicine, Chungbuk National University Hospital, Korea.
Sang
S
Hi Park
Yong Wook Jeon, Department of Anesthesiology and Pain Medicine, Chungbuk National University Hospital, Korea.
Yong
Y
Wook Jeon
Jin Ho Bae, Dept. of Anesthesiology and Pain Medicine, College of Medicine, Chungbuk National University, Korea.
Jin
J
Ho Bae
Tae Soo Lee, Dept. of Biomedical Engineering, College of Medicine, Chungbuk National University, Korea.
Tae
T
Soo Lee
Myoung Hwan Kim, Laboratory Animal Research Center, Chungbuk National University, Korea.
Myoung
M
Hwan Kim
Young Jin Choi, Department of Surgery, College of Medicine, Eulji University, Korea.
Young
Y
Jin Choi
Cardiac output; First heart sound; Heart rate; Stethoscope