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Paramedic Interpretation of Prehospital Lead-II ST-Segments

Published online by Cambridge University Press:  28 June 2012

Robert Hill ,
Michael Heller ,
Alexander Rosenau ,
Scott Melanson ,
David Pronchik ,
John Patterson  and
H. Gulick
Robert Hill
Affiliation:
St. Luke's Hospital, Bethlehem, Pennsylvania, USA
Michael Heller*
Affiliation:
Emergency Medicine Residency of the Lehigh Valley, Department of Emergency Medicine, St. Luke's Hospital, Bethlehem, Pennsylvania, USA
Alexander Rosenau
Affiliation:
Lehigh Valley Hospital, Allentown, Pennsylvania, USA
Scott Melanson
Affiliation:
St. Luke's Hospital, Bethlehem, Pennsylvania, USA
David Pronchik
Affiliation:
St. Luke's Hospital, Bethlehem, Pennsylvania, USA
John Patterson
Affiliation:
St. Luke's Hospital, Bethlehem, Pennsylvania, USA
H. Gulick
Affiliation:
Allentown EMS, Allentown, Pennsylvania, USA
*
Emergency Medicine Residency, 801 Ostrum Street, Bethlehem, PA 18015USA
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Abstract

Objective:

To determine the reliability of ST-segment interpretation by paramedics from lead-II rhythm strips obtained in the prehospital setting.

Design:

Prospective, blinded study of 127 patients transported by an urban/rural emergency medical services system with complaints consistent with ischemic heart disease.

Methods:

Emergency department physicians asked emergency medical technician-paramedics (EMT-P) via radio to evaluate ST-segments for elevation or depression and grade it as “mild,” “moderate,” or “severe.” Then, this rhythm strip was interpreted blindly by emergency physicians who also interpreted the lead-II obtained from a 12-lead electrocardiogram (ECG) obtained in the emergency department (ED). The field interpretation was compared with the subsequent readings and the final in-patient diagnosis using positive predictive value (PPV), negative predictive value (NPV), and the Kappa statistic. Markedly discrepant interpretations were analyzed separately.

Results:

Using physician interpretation as the reference standard, paramedic interpretation of the lead-II ST-segments obtained in the prehospital setting was correct (within ±1 gradation) in 113 out of 127 total cases (89%). Of 105 patients for whom final hospital diagnosis was available, the ST-segment on the rhythm strip obtained in the prehospital setting, had a positive predictive value of 74% and a negative predictive value of 85% for myocardial ischemia or myocardial infarction (MI) (p <0.001, Kappa = 0.59). Discordant interpretations between the paramedics and emergency physicians often were related to a basic misunderstanding of rhythm strip morphology.

Conclusion:

Field interpretation of ST-segments by paramedics is fairly accurate as judged both by emergency physicians and correlation with final patient outcome, but its clinical utility is unproved. A small but clinically significant number of outliers, consisting of markedly discrepant false positives, reflects paramedic uncertainty in identifying the deviations of the ST-segment.

Keywords

electrocariogramlead-IImyocardial ischemiaparamedicsprehospital ECGrhythm stripST-segments
Type
Original Research
Information
Prehospital and Disaster Medicine , Volume 12 , Issue 2 , June 1997 , pp. 70 - 73
Copyright
Copyright © World Association for Disaster and Emergency Medicine 1997

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