title: Correlation of blood pressure and the ratio of S1 to S2 as measured by esophageal stethoscope and wireless bluetooth transmission.
abstract: Objective : Esophageal stethoscope has the advantage of being non-invasive, easily placed and capability to monitor the heart sound. This study was designed to determine whether the ratio of S1 to S2 analyzed by esophageal stethoscope and wireless bluetooth transmission can be accurate indicator that express the correlation with blood pressure.
  
  
  METHODS
  Total 33 adult male and female without cardiac disorder and with normal heart rhythm were selected randomly as the subjects of this Study. Two microphones were used with one for acquisition of heart sound by connecting it to the esophageal stethoscope while the other was used to measure the background noise in the operating room. After having transmitted the heart sound measured with the esophageal stethoscope to the receiver by using bluetooth module, it was saved in PC and outputted, following removal of noise in the operating room and the respiratory sound. S1 and S2 were measured with computation of the ratio of S1 to S2. Correlations between the systolic blood pressure with each of the S1, S2 and ratio of S1 to S2 were examined by using correlation analysis.
  
  
  RESULTS
  The ratio of S1 to S2 displayed the highest correlation with the systolic blood pressure, with S1 and S2 also displaying positive correlation with the systolic blood pressure.
  
  
  CONCLUSIONS
  As the result of analysis of the heart sound and the systolic blood pressure measured by using the esophageal stethoscope, the radio of S1 to S2 displayed greater correlation with the systolic blood pressure in comparison to the S1.
authors.affiliation: Kyoung Hoon Lim, Department of Anesthesiology and Pain Medicine, Chungbuk National University Hospital, Republic of Korea.
authors.forename: Kyoung
authors.initials: K
authors.lastname: Hoon Lim
authors.affiliation: Young Duck Shin, Department of Anesthesiology and Pain Medicine, Chungbuk National University Hospital, Republic of Korea.
authors.forename: Young
authors.initials: Y
authors.lastname: Duck Shin
authors.affiliation: Sang Hi Park, Department of Anesthesiology and Pain Medicine, Chungbuk National University Hospital, Republic of Korea.
authors.forename: Sang
authors.initials: S
authors.lastname: Hi Park
authors.affiliation: Jin Ho Bae, Department of Anesthesiology and Pain Medicine, Chungbuk National University Hospital, Republic of Korea.
authors.forename: Jin
authors.initials: J
authors.lastname: Ho Bae
authors.affiliation: Hong Jae Lee, Department of Anesthesiology and Pain Medicine, Chungbuk National University Hospital, Republic of Korea.
authors.forename: Hong
authors.initials: H
authors.lastname: Jae Lee
authors.affiliation: Seon Jung Kim, Department of Anesthesiology and Pain Medicine, Hankook General Hospital, Republic of Korea.
authors.forename: Seon
authors.initials: S
authors.lastname: Jung Kim
authors.affiliation: Ji Yun Shin, Department of Biomedical Engineering, Chungbuk National University Hospital, Republic of Korea.
authors.forename: Ji
authors.initials: J
authors.lastname: Yun Shin
authors.affiliation: Young Jin Choi, Department of Surgery, Eulji University Hospital, Republic of Korea.
authors.forename: Young
authors.initials: Y
authors.lastname: Jin Choi
keywords: Blood pressure; Esophageal; Heart sounds; Stethoscope