Prone and Supine 12-Lead ECG Comparisons: Implications for Cardiac Assessment During Prone Ventilation for COVID-19

Performing Accurate Standard 12 Lead ECGs on patients with Burns to the Chest

The use of the electrocardiogram (ECG) in critical care settings is a long-established cardiovascular monitoring tool. The effectiveness of the routine 12-lead ECG relies on accurate lead placement that is consistent and replicable. Improper lead placement may display erroneous ECG patterns and affect patient management decisions.1,2 In the setting of an acute injury, such as a torso burn to the ventral surface, accurate lead placement may be compromised or impossible. The regional burn center, which is part of our organization, sees approximately 500 patients per year. Of those patients, burns to the chest accounted for 21% of admissions during 2020 and 2021. This significant fraction of burn injury patients requires modification of our standard approach to provide an accurate ECG. Baseline ECGs are routinely acquired on the burn unit per protocol and for monitoring of patient response to numerous pharmaceutical therapies.

Easily Neglected Manifestations in Electrocardiogram in the Prone Position

This case report describes a patient in their 70s with chronic obstructive pulmonary disease and hypertension who presented with a 2-day history of cough, expectoration, and shortness of breath.

Anatomical considerations and clinical interpretation of the 12-lead ECG in the prone position: a prospective multicentre study

AIMS

The aim of this study is to provide guidance for the clinical interpretation of electrocardiograms (ECGs) in prone position and to establish the electroanatomic explanations for the possible differences to supine position ECGs that may be observed. Additionally, to determine if prone back ECG can be used as an alternative to standard ECG in patients who may benefit from prone position.

METHODS AND RESULTS

The ECG in supine (standard ECG), prone back (precordial leads placed on the patient's back), and prone anterior position (precordial leads placed in the standard position with the subjects in prone position) were prospectively examined on 85 subjects. Comparisons of ECG parameters between these positions were performed. Computed tomography (CT) scans were performed in both positions to determine possible electroanatomic aetiologies for prone-associated ECG changes. There were significant differences in QRS amplitude in Leads V1-V5 between supine and prone positions. Q waves were more frequently observed in prone back position vs. supine position (V1: 74.1 vs. 10.6%, P < 0.0001; V2: 23.5 vs. 0%, P < 0.0001, respectively). Flat and inverted T waves were more common in prone back leads (V1: 98 vs. 66%, P < 0.0001; V2: 96 vs. 8%, P < 0.0001; V3: 45 vs. 7%, P < 0.0001). The 3D-CT reconstructions measurements corroborated the significant inverse correlation between QRS amplitude and the distance from the centre of the heart to the estimated lead positions.

CONCLUSION

In prone back position ECG, low QRS amplitude should not be misinterpreted as low voltage conditions, neither should Q waves and abnormal T waves are considered anteroseptal myocardial infarction. These changes can be explained by an increased impedance (due to interposing lung tissue) and by the increased distance between the electrodes to the centre of the heart.