The Feedback Device Says Everything Is Wrong
A 74-year-old man in a telemetry bed is found unresponsive and pulseless with agonal gasps. A five-person code team arrives within 40 seconds and compressions begin. The compressor is using a CPR feedback device that reads: rate 138/min, depth 3.6 cm (1.4 in), with "leaning" alerts on most compressions. A second rescuer is bagging with a bag-valve mask at roughly 20 breaths/min and 700 mL per breath. The team pauses compressions for 14 seconds at each rhythm check and swaps compressors during the same pause. There is no advanced airway yet. An arterial line placed earlier in the day is still functioning, and the capnograph reads ETCO2 12 mmHg. The first rhythm check shows asystole.
1. Rank the three highest-yield corrections and explain how you would fix each with the equipment already in the room.
Read the worked answer
1. Depth and rate (highest yield). 3.6 cm is well short of the 5–6 cm target, and 138/min is above the 100–120/min range - fast, shallow compressions produce poor stroke volume and poor coronary perfusion. Fix: use the device's real-time display as biofeedback, coach out loud ("push to the line, let it click"), have the compressor kneel closer or use a step if the bed height is wrong, and if two corrections are not achieved within ~30 seconds, switch compressors early rather than waiting for the 2-minute mark.
2. Leaning / incomplete recoil. Leaning raises intrathoracic pressure between compressions and drops coronary perfusion pressure. Cue the rescuer to lift the heel of the hand 1–2 cm off the chest while keeping contact, and watch the arterial line for a rising diastolic pressure as recoil improves.
3. Hyperventilation. 20 breaths/min at 700 mL is both too fast and too large: 2 breaths per 30 compressions, each over 1 second, just enough to see the chest rise. Excess ventilation raises intrathoracic pressure, reduces venous return, and causes gastric insufflation. Consider a two-person BVM technique with an oral airway and continuous waveform capnography.
2. What compression fraction is this team likely achieving, and what structural changes would raise it?
Read the worked answer
A 2-minute cycle is 120 seconds of compression time plus a 14-second rhythm-check pause, plus several seconds lost to the compressor swap, bagging gaps, and any pulse checks - so roughly 120/140–145 seconds, about 82–86%, and likely lower in practice because the swap is unrehearsed.
The floor is 60%; the practical target is 80–90%, with every pause under 10 seconds.
Structural changes:
- Combine tasks into one pause: rhythm check, compressor swap, and any monitor adjustment done in parallel, not sequentially.
- Announce a countdown: "5 seconds, 4, 3…" and have the relief compressor with hands hovering above the chest before the pause begins.
- Pre-charge the defibrillator during compressions when the rhythm is shockable (not applicable now) so the pause is shock-only.
- Limit pulse checks to 10 seconds and only when a rhythm is organized.
- Assign a designated timekeeper/coach whose only job is to call rate, depth, recoil, and pause length.
3. The resident wants to intubate now. Argue for or against, using the arterial line and capnograph data.
Read the worked answer
Against, at this moment. ETCO2 of 12 mmHg and a low arterial diastolic pressure indicate that forward flow and coronary perfusion are marginal - the limiting factor is compression quality, not airway. In asystole with a functioning bag-valve mask and a five-person team, intubation is not time-critical, and the attempt would almost certainly cost a prolonged compression interruption.
Reasonable options:
- Improve compressions first (depth/rate/recoil) and re-check ETCO2; a rise toward 20+ suggests you are fixing the right problem.
- If an airway is needed, place an extraglottic device - faster, higher first-pass success, less interruption.
- If intubation is attempted, do it without stopping compressions by having the laryngoscopist work at the head of the bed during ongoing compressions, with a brief (<10 s) pause only for tube passage, and confirm with waveform capnography.
ETCO2 <10 mmHg persisting despite good technique is a poor prognostic sign but should prompt a search for reversible causes and better CPR, not immediate airway heroics.