Abstract 247: Digitization of Electrocardiogram from Telemetry Prior to In-Hospital Cardiac Arrest
Background: Telemetry is commonly used to alert clinicians to respond to in-hospital cardiac arrest (I-HCA). Analyzing electrocardiogram (ECG) over an extended period of time prior to I-HCA is often time consuming because digital records of the ECG from telemetry are not available in the majority of hospitals. The objective of this study was to develop an algorithm to digitize full disclosure ECG papers in order to perform automated measurements.
Methods: In a multi-center study, full-disclosure ECG papers (25 mm/s paper speed) within one hour of I-HCA of 42 cardiovascular patients with initial rhythms of pulseless electrical activity (PEA) and asystole were obtained from telemetry. Digital ECGs from one of the centers was also available for seven of these patients with a sampling rate of 500 Hz. The duration for each full-disclosure ECG paper was either 7.6 or 10.8 seconds as dictated by each hospital’s monitoring system. An algorithm to digitize the full-disclosure ECG papers was developed according to the shortest path method. The heart rate was measured manually (averaging R-R intervals within one minute) for ECG papers and automatically for digitized and digital ECGs using LabChart. Correlation coefficients were obtained by comparing the heart rates between the manual measurements of ECG papers and automated measurements of digitized and digital ECGs for 42 patients. Statistical methods were used to demonstrate the validity of digitization by comparing the digitized and digital signals for seven patients, including correlation coefficient, percentage root mean square difference (PRD), root mean square (rms), and signal to noise ratio (SNR).
Results: The mean of heart rate for the manual, digitized and digital ECG measurement was 87.99±16.03, 88.71±16.21 and 87.96±17.35 respectively. The mean of correlation coefficient was 95.11% (p<0.05) for comparing heart rate by the manual and automated measurements of digitized ECG for 42 patients. The average PRD, rms, and SNR between digitized and digital signals were 1.5%, 1.9%, and 36.56dB respectively.
Conclusion: Validity of digitization method was demonstrated by mathematical measures. Digitized ECG provides an efficient and accurate way of measuring heart rate over an extended period of time.
Author Disclosures: L. Wang: None. R. Soroushmehr: None. K. Najarian: None. M. Attin: None.
- © 2014 by American Heart Association, Inc.