Book 00 · Page 4141 / 80

Rhythms that kill, rhythms that wait

Six labelled rhythm strips: normal sinus, sinus bradycardia, sinus tachycardia, atrial fibrillation, ventricular tachycardia and ventricular fibrillation. — Fig 1.41 · pending clinical review

The exam rarely asks the candidate to measure a PR interval. It asks what to do next, and that answer comes from the patient, not the tracing. Sort every rhythm into the pile that changes the next sixty seconds.

	ACT NOW	ASSESS AND MONITOR
Rhythm	Ventricular fibrillation, pulseless ventricular tachycardia	Sinus tachycardia
	Asystole, pulseless electrical activity	Atrial fibrillation with a controlled ventricular response
	Torsades de pointes	First-degree block, Mobitz type I
	Complete heart block with hypotension	Infrequent asymptomatic premature ventricular contractions
Pulse?	Absent, or present and unstable	Present
Stable?	No	Yes
First action	Compressions, then defibrillate the shockable ones; pace the symptomatic block	Find and treat the cause; continue monitoring
What they test	Can the candidate act without a diagnosis	Can the candidate resist over-treating

Reading the left column

Ventricular fibrillation and pulseless ventricular tachycardia have no perfusing pulse. Start compressions, defibrillate as soon as the device is ready, and resume compressions immediately afterward.
Asystole and pulseless electrical activity are not shockable. High-quality compressions continue while the reversible cause is hunted.
Torsades de pointes is a polymorphic ventricular tachycardia with a twisting axis. Magnesium is the treatment in the patient with a pulse; a pulseless patient gets defibrillation.
Complete heart block with hypotension needs transcutaneous pacing, not observation.

Reading the right column

Sinus tachycardia is a symptom. Find the fever, the pain, the hypovolemia, the hypoxia, or the anxiety driving it.
Controlled atrial fibrillation needs a rate plan and a stroke-prevention plan, both of which are decisions, not emergencies.
Mobitz type I lengthens the PR interval progressively and then drops a beat. Review contributing factors and keep watching.

The fork: No pulse sends you to compressions and the shock decision. Pulse present but unstable sends you to synchronized cardioversion. Pulse present and stable sends you to assessment.

Margin notetreat the patient; the monitor has no pulse.

Watch outnever delay compressions to interpret a rhythm.

TakeawayPulse first, stability second, rhythm name third.

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