2.2 Evaluate–Identify–Intervene Sequence

The continuous loop, not a single checklist

PALS is built around a systematic approach that never truly ends while the patient is critically ill. The three words to memorize are:

1. Evaluate
2. Identify
3. Intervene

Then repeat. Every intervention changes physiology, so every intervention requires reassessment. On the written exam and in megacode testing, candidates lose points when they "do something" and fail to recheck the child's response.

Evaluate: what you gather, and in what order

Evaluate means gathering the clinical data needed to classify the problem. The evaluation expands in layers:

Evaluate is dynamic. A child who looked only moderately distressed on arrival can deteriorate during history-taking. Keep eyes on appearance, effort, and color even while someone else obtains SAMPLE details.

Core evaluation questions the team should be able to answer at any moment:

• Is the airway open and maintainable?
• Is oxygenation and ventilation adequate?
• Is perfusion adequate (pulses, skin, capillary refill, blood pressure when available)?
• What is the neurologic status (AVPU/GCS, pupils, glucose)?
• Are there immediately reversible causes visible on exam?

Identify: map findings to a problem category

Identify converts raw findings into a working category that selects the correct management path. PALS organizes life-threatening problems into broad buckets:

Identification is not a final diagnosis. You do not need the organism name or the exact congenital lesion in the first minute. You need the physiology category that tells the team which interventions save the next five minutes of life.

Within respiratory problems, identification also narrows the anatomic/physiologic subtype later (upper airway, lower airway, lung tissue disease, disordered control of breathing). Within shock, you later refine hypovolemic, distributive, cardiogenic, or obstructive. Those refinements are covered in later chapters; the evaluate–identify–intervene loop is the scaffold that holds them.

Intervene: act on the category, then reassess

Intervene means performing the actions that reverse or stabilize the identified problem while evaluation continues. Principles:

1. Life threats first. Open the airway and support breathing before a detailed abdominal exam. Start CPR when arrest criteria are met—do not finish a full SAMPLE first.
2. Match the intervention to the category. Oxygen and assisted ventilation dominate respiratory failure; isotonic fluid boluses dominate most hypovolemic/distributive shock presentations; careful fluid strategy and inotropes matter in cardiogenic shock; relief of obstruction (needle decompression, pericardiocentesis) matters in obstructive shock.
3. Use closed-loop communication. The team leader states the intervention; the team member repeats it back and reports completion ("epinephrine 0.01 mg/kg IV given").
4. Reassess after every major intervention. Did SpO2 rise? Did work of breathing improve? Did capillary refill and pulses improve? Did mental status change? If not, re-identify (wrong category? wrong dose? progression to failure?).

Prioritization when multiple problems coexist

Real children rarely present with a single pure problem. Common multi-problem patterns:

• Septic shock with respiratory failure — support breathing and circulation; do not choose one and ignore the other.
• Trauma with hypovolemia and airway compromise — airway/C-spine considerations and hemorrhage control proceed in parallel with breathing support.
• Cardiogenic shock with pulmonary edema — oxygen/ventilation support plus careful fluid strategy (often smaller boluses with early reassessment) rather than large undifferentiated fluid loads.
• Bradycardia from hypoxia — oxygenation and ventilation come before atropine; many pediatric bradycardias are respiratory in origin.

Prioritization rules of thumb taught in PALS:

1. Oxygenation and ventilation almost always come first or simultaneously with circulation support, because pediatric arrest is so often hypoxic.
2. If the child meets CPR criteria, compressions and ventilation supersede nearly everything except immediate defibrillation for witnessed monitored VF/pVT in some settings.
3. Among simultaneous needs, fix what will kill the patient in the next minutes (obstructed airway, absent breathing, no pulse) before refining the differential diagnosis.
4. When unsure between categories, treat the most immediately life-threatening possibility that is reversible while gathering more data.

Linking the loop to PALS algorithms

Once you identify a category, PALS algorithms provide the structured intervention path:

The evaluate–identify–intervene loop feeds the algorithms: you do not jump into a drug dose table without first identifying the rhythm/problem. Conversely, once inside an algorithm, you continue to evaluate (rhythm check, pulse check, ETCO2, diastolic BP goals during CPR when arterial line is present) and intervene on reversible causes (Hs and Ts).

Worked example of one full loop

Scene: 9-month-old with 2 days of vomiting and diarrhea.

1. Evaluate (PAT): listless, poor interactiveness (abnormal appearance); no retractions (work of breathing relatively normal); mottled skin (abnormal circulation).
2. Identify (working): circulatory problem—likely hypovolemic shock (still need BP and full primary to say compensated vs hypotensive).
3. Intervene: high-flow oxygen as indicated, rapid primary assessment, vascular access (IV/IO), isotonic crystalloid 10–20 mL/kg bolus with reassessment; monitor glucose.
4. Re-evaluate: after the bolus, capillary refill improves from 4 s to 2 s, child becomes more interactive, SBP now above hypotensive threshold → identify improvement; continue careful fluids and cause-specific care. If the child worsens or develops crackles/hepatomegaly after fluids, re-identify (possible cardiogenic component or fluid overload) and change the plan.

Common exam traps

• Stopping after one intervene. The correct answer often includes reassessment language.
• Treating the monitor, not the child. A number on the screen does not replace the evaluate step if the PAT shows clinical failure.
• Forcing a single label too early. Identify a category first; refine the subtype as data arrive.
• Ignoring cardiopulmonary failure. When both respiratory and circulatory sides are collapsing, you are past "simple distress"—support ABCs aggressively and prepare for arrest care.

If you can narrate evaluate → identify → intervene → reassess for respiratory, shock, arrhythmia, and arrest scenarios, you have the cognitive skeleton of the entire PALS provider course.