Temporary Pacemaker: Sensing, Capture and Perfusion
How do sensing, output and capture differ in temporary pacing?
Temporary pacemaker assessment distinguishes sensed native activity, delivered stimuli, electrical capture and the patient’s mechanical response. In demand pacing, an appropriately sensed native beat can inhibit a stimulus, so absent spikes are not always a failure. A paced QRS still does not establish adequate forward flow or tissue perfusion.
Key takeaways
- Normal demand inhibition can explain a period without pacing spikes.
- Output and sensitivity are different controls with different units.
- Electrical capture does not replace assessment of perfusion.
In this video
- Temporary pacemaker troubleshooting
- Four links
- Sensing and the timer
- Output and sensitivity
- Undersensing and oversensing
- Electrical capture
- Capture and your patient
- One patient, one strip
- Reading the strip second by second
- Back to the bedside
- If the pulse is gone
- Two thresholds
- The pacemaker with no spikes
- Interview question
- Quick check
Can no pacing spikes be normal?
A demand mode responds to sensed cardiac activity. In VVI, an appropriately detected ventricular event can inhibit a scheduled ventricular stimulus. The absence of a spike after a qualifying native beat can therefore represent intended behavior.
A strip with unwanted pauses raises a different question, including possible sensing or output problems. The tracing alone cannot establish a hardware cause or determine the correct setting change.
How do output and sensitivity differ?
Output describes the delivered stimulus and is commonly expressed as current in milliamperes. Sensitivity describes the signal threshold for detecting native activity and is expressed in millivolts. A lower sensitivity number permits detection of a smaller signal; it does not mean a larger pacing stimulus.
These are conceptual distinctions, not instructions for turning a control. Device-specific instructions, lead configuration and the patient’s clinical condition remain necessary for any operational decision.
What counts as effective pacing?
A pacing artifact is evidence of stimulus delivery. The expected electrical response provides evidence of capture, while a pulse and perfusion assessment address the mechanical result. These steps cannot be collapsed into one observation.
A paced electrical pattern with poor perfusion is still a clinical problem. This lesson does not prescribe output margins, wire manipulation or troubleshooting button sequences, and it does not substitute a hardware checklist for patient assessment.
