Evaluation of transesophageal atrial pacing in the prone and lateral position
© Current Science Ltd 2000
Published: 21 March 2000
Transesophageal atrial pacing (TEAP) is used for temporary treatment of hypotension and/or low cardiac output caused by sinus bradycardia or atrioventricular junctional rhythm. It can also be used for temporary overdrive pacing of reentrant tachycardias. A pacing esophageal stethoscope (PES) is easy to place in supine intubated patients. However, no guidelines exist for PES placement in the prone or laterally positioned intubated patient.
After IRB approval and written informed consent, an 18 Fr PES with 1 cm depth markings (Model 550 CardioCommand, Inc) was inserted to a depth of insertion (DOI) of 44 cm from the edge of the maxillary alveolar ridge into the esophagus of 30 adult intubated patients in the supine position. With the pacing rate set 10–20 beats per min faster than the patient's intrinsic heart rate and the current output on the pulse generator (Model 2A) set at its lowest current setting (5.5 mA), the current was gradually increased until atrial capture was achieved. The minimum current producing continuous atrial capture throughout the respiratory cycle was recorded as the pacing threshold. The PES was then withdrawn 1 cm at a time and pacing thresholds were re-determined for each DOI from 44 to 25 cm inclusive. After data collection in the supine position, each patient was then positioned into either the prone (P), right (RLD) or left lateral decubitus (LLD) position. Data were collected in the same manner after the patients' position was changed. The width of the "Region of Capture" (ROC) represents the number of DOI locations where TEAP could be achieved with thresholds 40 mA. The "Optimal" DOI represents where the minimum TEAP current threshold (THmin) occurred. Data is presented as mean ± standard deviation.
TEAP was accomplished in all 30 patients both in the supine and prone or lateral positions. The Optimal DOI increased on average only 1.2 cm (from 34.0 to 35.2 cm) after positioning. Similarly, the average width of ROC increased only by 0.5 cm (from 12.4 to 12.9 cm). The THmin (mean 14.4± 2.7 mA) never decreased after placement of a supine patient into the prone position. It either remained unchanged or increased (minimum to maximum individual difference 0–8 mA). However, there was considerable variability in how the THmin, Optimal DOI, and ROC changed with the lateral position. Neither phrenic nerve pacing, brachial plexus stimulation, nor induction of arrhythmias was observed in any patient.
This study demonstrates that TEAP with a PES can be successful in patients who are subsequently turned into the prone or lateral positions with minimal adjustments. TEAP may be initiated in the prone or lateral positions with the same insertion recommendations as those for patients in the supine position.