8.3 Asystole & PEA
Key Takeaways
- Asystole and PEA are nonshockable rhythms—do not defibrillate them.
- Management pillars: continuous high-quality CPR, epinephrine as soon as possible, airway/ventilation support, and aggressive treatment of reversible causes (H’s and T’s).
- Early epinephrine in initial nonshockable rhythms is associated with better outcomes—do not wait multiple cycles if access can be obtained.
- Confirm asystole carefully: check leads/connections, consider gain, and verify in at least one additional lead (or more) so fine VF is not missed.
- Hypoxia is a dominant reversible cause in pediatric PEA/asystole—optimize oxygenation and ventilation while you treat other H’s/T’s.
Nonshockable Arrest: Asystole and PEA
When the rhythm is asystole or pulseless electrical activity (PEA), electricity will not restart effective output. Defibrillation of true asystole/PEA wastes time, interrupts CPR, and does not improve outcome. The nonshockable pathway is built on CPR + early epinephrine + airway/ventilation + reversible causes.
Definitions
| Rhythm | What it is | Shock? |
|---|---|---|
| Asystole | No ventricular electrical activity (“flatline”) | No |
| PEA | Organized (or semi-organized) electrical activity without a palpable pulse / effective perfusion | No |
| Fine VF | Very low-amplitude VF that can look almost flat | Yes — treat as VF |
PEA is a clinical diagnosis: the monitor shows electrical activity that might even resemble a “normal” rate/complexes, but the child has no pulse. Common PEA-associated contexts in pediatrics include severe hypoxia, hypovolemia, tension pneumothorax, tamponade, toxin effects, and severe metabolic derangements.
Confirming asystole (do not miss fine VF)
Before locking into a pure asystole mindset:
- Confirm pad/lead connections and power.
- Check that the gain/amplitude is adequate so fine VF is not hidden.
- Confirm the flatline in at least one other lead (preferably more) when multi-lead monitoring is available.
If the rhythm is actually fine VF, the correct path is defibrillation—not endless epinephrine-only asystole care. Conversely, do not “try a shock just in case” for clearly confirmed asystole/PEA as a routine.
Management Priorities for Asystole/PEA
1. High-quality CPR without unnecessary pauses
Compressions are the only artificial cardiac output. Keep rate, depth, recoil, and compression fraction high. Pause only briefly (~2-minute cycles) for rhythm/pulse checks. If still nonshockable and pulseless, resume CPR immediately.
2. Epinephrine as soon as possible
For initial nonshockable rhythms, give epinephrine early—as soon as IV/IO access is available during CPR. Early epinephrine in nonshockable arrest is associated with better outcomes (higher ROSC/survival signals in resuscitation science teaching). Dose and interval are detailed in Section 8.4: 0.01 mg/kg IV/IO every 3–5 minutes.
Do not withhold epinephrine until after multiple fruitless cycles if access can be obtained now. Do not prioritize endotracheal drug delivery over getting IV/IO.
3. Airway and ventilation—especially hypoxia
Because pediatric arrest is so often secondary to respiratory failure, the nonshockable pathway is inseparable from airway management:
- Open the airway; provide effective bag-mask ventilation with oxygen
- Ensure chest rise; rule out obstruction
- Avoid hyperventilation
- Advance the airway if needed without prolonged CPR interruptions
- Treat the underlying respiratory disease process when identified
Hypoxia sits at the top of the reversible-cause list in many pediatric PEA/asystole cases. Fixing oxygenation/ventilation is not optional “extra credit”—it is core therapy.
4. Search and treat H’s and T’s aggressively
While CPR and epinephrine run, the team leader assigns someone to hunt reversible causes:
H’s (high-yield pediatric framing)
| Cause | Pediatric clues | Immediate actions |
|---|---|---|
| Hypovolemia | Fluid losses, sepsis capillary leak, hemorrhage | Isotonic fluid boluses; blood if hemorrhage |
| Hypoxia | Respiratory failure, drowning, obstruction | Airway, O₂, ventilation |
| Hydrogen ion (acidosis) | Prolonged arrest, toxic alcohols, metabolic disease | Support ventilation/perfusion; specific therapy per cause |
| Hypo-/hyperkalemia | Renal disease, DKA shifts, suctioned/ileostomy losses | Electrolyte-directed therapy |
| Hypothermia | Environmental exposure, drowning | Rewarming per protocol |
| Hypoglycemia | Infants, liver failure, sepsis | Check glucose; treat documented hypoglycemia |
T’s
| Cause | Pediatric clues | Immediate actions |
|---|---|---|
| Tension pneumothorax | Trauma, positive-pressure ventilation, unequal BS | Needle decompression |
| Tamponade | Trauma, post-op cardiac | Fluids bridge; drainage when indicated |
| Toxins | Overdose, medication error | Antidotes/supportive care |
| Thrombosis (pulmonary/coronary) | Selected high-risk settings | Expert reperfusion pathways |
| Trauma | Multisystem injury | Hemorrhage control + cause-specific obstruction relief |
(Chapter 11 expands reversible causes and special circumstances.)
Rhythm Changes and Common Exam Traps
Arrest rhythms can change. A child may start in PEA, convert to VF after CPR/epinephrine, or develop organized rhythm with ROSC. Reassess every cycle and switch pathways when the rhythm branch changes.
Trap list
| Trap | Why it is wrong |
|---|---|
| Defibrillating confirmed asystole “just in case” | Not indicated; delays CPR/cause treatment |
| Treating PEA with synchronized cardioversion | PEA is pulseless arrest, not unstable tachycardia with a pulse |
| Delaying epinephrine for prolonged intubation attempts | Early epi matters on the nonshockable path; airway support can start with bag-mask |
| Ignoring hypoxia while cycling drugs | Respiratory failure is a leading pediatric driver |
| Declaring asystole from a single unconfirmed flat lead | May miss fine VF or loose leads |
Clinical scenario
A 9-month-old with bronchiolitis becomes apneic and pulseless. Monitor: asystole after lead confirmation. Actions: CPR, bag-mask with oxygen, IO access within seconds, epinephrine 0.01 mg/kg, suction/airway positioning, prepare for advanced airway if bag-mask fails—no shock. If later rhythm is VF, immediately pivot to defibrillation at 2 J/kg.
Bottom line for 8.3: Asystole/PEA → do not defibrillate → CPR + early epinephrine + airway/ventilation + H’s/T’s, with hypoxia front-of-mind, and confirm asystole so fine VF is not missed.
A child in cardiac arrest has confirmed asystole after leads and gain are checked. Which action is appropriate?
Why must providers confirm asystole with lead/gain checks and more than a single casual glance at one tracing?
In pediatric PEA after progressive respiratory failure, which reversible-cause emphasis is most characteristic of PALS teaching?