PALS (Pediatric Advanced Life Support) uses a structured sequence of diagnostic assessments to evaluate critically ill or injured children. These assessments move from a rapid visual scan to hands-on examination to lab tests and imaging, each layer adding detail. Understanding what each phase involves is essential for anyone preparing for PALS certification or working in pediatric emergency care.
The Pediatric Assessment Triangle
The very first diagnostic tool in PALS is the Pediatric Assessment Triangle, or PAT. This is a quick, hands-off evaluation you can complete in under 30 seconds from across the room. It has three components: appearance, work of breathing, and circulation.
Appearance covers the child’s level of consciousness, facial expression, complexion, and motor activity or gait. A child who is alert, interactive, and moving normally looks very different from one who is limp, staring blankly, or unresponsive. Work of breathing is assessed by watching respiratory rate, chest movement, airway sounds, and visible effort. Circulation is evaluated by looking at skin color, moisture, and any visible bleeding. Together, these three observations form an immediate impression of how sick the child is and which body system needs attention first.
The Primary Assessment: ABCDE
Once the PAT gives an initial picture, the primary assessment follows a structured ABCDE sequence. This is the hands-on phase.
Airway
If a child responds in a normal voice, the airway is open. A changed voice, noisy breathing (like stridor), or increased breathing effort suggests a partial obstruction. A completely blocked airway produces no air movement despite visible effort, sometimes called the “see-saw” sign, where the chest and abdomen move in opposite directions.
Breathing
Breathing assessment includes respiratory rate, chest wall symmetry, and oxygen saturation measured by pulse oximetry. Normal respiratory rates vary widely by age: infants breathe 30 to 60 times per minute, toddlers 24 to 40, school-age children 18 to 30, and adolescents 12 to 16. Signs of trouble include use of extra muscles to breathe, bluish skin color (cyanosis), distended neck veins, or a windpipe shifted to one side.
Circulation
Circulatory assessment looks at skin color and temperature, capillary refill time (normally under 2 seconds), pulse rate, and blood pressure. Normal heart rates also shift with age. Newborns to 3 months range from 85 to 205 beats per minute when awake, while children over 10 fall between 60 and 100. Blood pressure thresholds for hypotension are age-specific: below 60 mmHg for newborns, below 70 mmHg for infants up to 12 months, and for children 1 to 10 years, the formula is 70 plus twice the child’s age in years. Children over 10 are considered hypotensive below 90 mmHg.
One critical point: blood pressure can remain normal even when a child is in early shock. This is called compensated shock, and its warning signs are subtler. The child may be irritable or inconsolable, may stare into space, or may not interact with a parent. Pulses may feel weak or unusually strong, capillary refill may take about 3 seconds, and urine output drops. By the time blood pressure actually falls (hypotensive or uncompensated shock), the child shows cool, mottled skin, very weak pulses, capillary refill over 4 seconds, and decreased consciousness. This late stage is considered a pre-arrest state.
Disability
The neurological check uses two main tools. The AVPU scale is a rapid screen: is the child Alert, responsive to Voice, responsive to Pain, or Unresponsive? For a more detailed score, PALS uses the Glasgow Coma Scale, which has a modified version for children under 2. It rates eye opening, verbal response, and motor response. In preverbal children, verbal scoring ranges from no response up to normal cooing and babbling, while motor scoring ranges from no movement up to spontaneous purposeful movement. For older children, verbal responses range from no sound to fully oriented speech, and motor responses range from no movement to following commands. Pupil reactions and blood glucose are also checked during this step.
Exposure
The final step in the primary assessment involves removing clothing to inspect the child’s entire body for signs of trauma, bleeding, rashes, or needle marks, while also checking body temperature. This step is kept as brief as possible to prevent heat loss.
The Secondary Assessment: SAMPLE History
After the primary assessment stabilizes immediate threats, the secondary assessment gathers a focused medical history using the SAMPLE mnemonic. This information typically comes from parents or caregivers.
- S (Signs and Symptoms): What the child is experiencing right now, including what prompted the call for help.
- A (Allergies): Not just prescription drug allergies, but reactions to over-the-counter medications and foods as well.
- M (Medications): Everything the child takes, including prescriptions, over-the-counter drugs, herbal supplements, and nutritional supplements.
- P (Past Medical History): Prior respiratory problems like asthma, cardiovascular history, whether the child was born premature or full-term, recent illnesses, and any recent surgeries.
- L (Last Meal): When the child last ate or drank anything, which matters for procedures that may require sedation or anesthesia.
- E (Events): What happened leading up to the illness or injury, when it started, and how long it has been going on.
Tertiary Assessment: Labs and Imaging
The tertiary assessment is where formal diagnostic tests enter the picture. These are not performed in the first 5 to 10 minutes of stabilization, especially in a child with severe respiratory distress, because the stimulation of drawing blood or moving a child for imaging can worsen the situation. Once the child is more stable, tests are ordered based on the suspected problem.
Laboratory Tests
Blood glucose is checked as soon as reasonably possible in all critically ill children, with special urgency for neonates and infants who burn through glucose reserves quickly. Beyond that, common labs include blood gases (arterial, venous, or capillary) to assess how well the lungs and circulation are delivering oxygen, electrolytes and kidney function markers, complete blood counts, clotting studies, and lactate levels. Lactate rises when tissues are not getting enough oxygen, making it a useful marker of shock severity. Blood and urine cultures help identify infections, and toxicology screens are ordered when poisoning or drug exposure is suspected.
Imaging Studies
Chest X-rays are among the most frequently used imaging tools, helping evaluate heart size, lung fields, and fluid around the lungs. An electrocardiogram (ECG) records the heart’s electrical activity and is used in cases of abnormal heart rhythms or cardiac arrest. An echocardiogram, which uses ultrasound to visualize the heart’s structure and pumping ability, is ordered when cardiogenic shock is suspected. Neck X-rays for suspected upper airway obstruction are noted in PALS materials but are generally considered unnecessary in most cases.
How the Assessments Work Together
The layered design of PALS assessments is intentional. The PAT takes seconds and tells you whether a child looks sick. The ABCDE primary assessment takes minutes and identifies which body system is failing. The SAMPLE history fills in context that changes treatment decisions. And the tertiary assessment confirms or refines the diagnosis with objective data. Each layer builds on the one before it, and the sequence repeats: after any intervention, you cycle back through the assessments to see whether the child is improving or deteriorating.
This “assess, intervene, reassess” loop is one of the defining features of PALS. The diagnostic assessments are not a one-time checklist but a continuous process that adapts as the child’s condition evolves.