Jun 12, 2021
Traditionally transcutaneous pacing involves a paramedic placing pads anterior/posterior (preferred), and turning up the milliamps until electrical capture is obtained. Electrical capture is obtained when a pacing spike is followed by a wide complex. The clinician will then try to palpate a pulse to confirm mechanical capture. Because the contractions of the pectoral muscles can tug on the muscles of the neck as well, AHA recommends palpating a femoral pulse versus a carotid (3) to avoid thinking you feel a pulse (false mechanical capture). Not only are events of false capture common, but there are even situations in which the paramedic swears they feel a pulse and observes the patient becoming more alert, and they never had mechanical capture.
I believe most of us are using SPO2 pleth wave to confirm mechanical capture versus the subjectivity of palpating a pulse, but even patients with a pulse can have poor pleth wave readings. I believe ultrasound-guided pacing is ideal and should become mainstream. I typically find I can get a parasternal long view on ultrasound with the pads placed as illustrated below. However, there are other views if your pad sweet spot is obstructing where you wanna put the probe.
This is nothing profound and is definitely not a new concept in emergency medicine. It is however a new concept for paramedics and another feather in the cap of prehospital ultrasound. This is a conversation between myself and Dr. Eydelman discussing this topic. Enjoy!