# PECARN Pediatric Head CT Decision Rule (Kuppermann 2009) > PECARN Pediatric Head CT Decision Rule (Kuppermann 2009) is a paid API for AI agents from api.magentlab.com, paid per call via x402, $0.005/call, status unknown (last checked 2026-09-15). Applies the PECARN pediatric head CT decision rule to classify children (age 0-17) as high, intermediate, or low risk for clinically important traumatic brain injury, recommending CT only for high-risk cases. ## Facts - Endpoint: GET https://api.magentlab.com/api/calc/pecarn_head - Price: $0.005/call - Payment: x402 - Status: unknown - Last checked: 2026-09-15 - Activations on Zero: 0 - Tags: x402 - Canonical page: https://www.zero.xyz/c/pecarn-pediatric-head-ct-decision-rule-kuppermann-2009-ccc9ff27 - Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_pzFWiXfjQ-Ak8GqWC0MEA Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently. ## How to call it through Zero Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`): ```sh zero fetch --capability pecarn-pediatric-head-ct-decision-rule-kuppermann-2009-ccc9ff27 ``` Example prompt: Run the PECARN head CT rule for a 6-year-old who fell more than 5 feet: GCS is 15 so gcs_le_14 is false, no altered mental status, no basilar skull fracture signs, no history of vomiting, no severe headache, no loss of consciousness, but severe mechanism is true and history of LOC is false. ## When to prefer this Use this endpoint when you need to apply the validated PECARN Kuppermann 2009 pediatric head CT rule specifically — for patients aged 0-17 with blunt head trauma where you need age-stratified (under 2 vs 2-17) CT decision support. Prefer this over generic clinical calculators when the decision rule must be traceable to a specific published algorithm. Do not use for adults, for Canadian CT Head / CATCH / CHALICE / NEXUS rules, or for PECARN intra-abdominal injury, febrile illness, or cervical spine variants. ## Known failure modes - Age 18 or above is rejected with a validation error — only ages 0-17 are accepted - Missing required boolean query parameters return a schema validation error - Ambiguous or non-boolean values for clinical flags cause parameter rejection - Conflicting clinical inputs (e.g. GCS <=14 flagged false but altered mental status true) are accepted as-is since magent does not validate clinical coherence - Network or payment failure (402 if x402 payment not attached) returns an HTTP 402 error ## How this service works PECARN pediatric head CT (Kuppermann 2009). Two age trees (under 2 vs 2-17). High if any age-applicable high-risk factor (GCS <=14 or altered mental status in both; palpable skull fracture if under 2; signs of basilar skull fracture if 2 or older), else intermediate if any age-applicable intermediate factor, else low. CT recommended only when high. Not a diagnosis. Not Canadian CT Head, CATCH, CHALICE, NEXUS, or PECARN IAI/febrile/c-spine. magent does not examine the patient. ## Output Returns a risk stratum (high, intermediate, or low), a CT recommendation (CT recommended only if high risk), the age-appropriate decision tree applied (lt_2 for ages 0-1, ge_2 for ages 2-17), and the specific risk factors that drove the classification. Not a clinical diagnosis; intended as decision support only. ## Request schema (JSON Schema) ```json { "type": "object", "$schema": "https://json-schema.org/draft/2020-12/schema", "required": [ "input" ], "properties": { "input": { "type": "object", "required": [ "type", "method" ], "properties": { "type": { "type": "string", "const": "http" }, "method": { "enum": [ "GET", "HEAD", "DELETE" ], "type": "string" }, "headers": { "type": "object", "additionalProperties": { "type": "string" } }, "queryParams": { "type": "object", "required": [ "age", "gcs_le_14", "altered_mental_status", "palpable_skull_fracture", "signs_basilar_skull_fracture", "nonfrontal_scalp_hematoma", "loc_ge_5_seconds", "not_acting_normally", "history_of_loc", "history_of_vomiting", "severe_headache", "severe_mechanism" ], "properties": { "age": { "type": "integer", "description": "Age in years (0-17). Age 0 and 1 use the lt_2 tree; age 2 through 17 use the ge_2 tree. Age 18 is rejected." }, "gcs_le_14": { "type": "boolean", "description": "GCS <=14 as assigned by the caller. true or false. High-risk in both trees. GCS 15 is not <=14. magent does not take a GCS integer." }, "history_of_loc": { "type": "boolean", "description": "History of loss of consciousness as assigned by the caller. true or false. Intermediate only on the ge_2 tree; parsed but not scored when age < 2." }, "severe_headache": { "type": "boolean", "description": "Severe headache as assigned by the caller. true or false. Intermediate only on the ge_2 tree; parsed but not scored when age < 2." }, "loc_ge_5_seconds": { "type": "boolean", "description": "Loss of consciousness >=5 seconds as assigned by the caller. true or false. Intermediate only on the lt_2 tree; parsed but not scored when age >= 2." }, "severe_mechanism": { "type": "boolean", "description": "Severe mechanism as assigned by the caller. true or false. Intermediate in both trees. Paper list: MVC ejection/rollover/death of another passenger; unhelmeted pedestrian or bicyclist struck by a motorized vehicle; fall >3 ft if <2 years or >5 ft if >=2 years; head struck by a high-impact object. magent does not classify mechanism or take fall height." }, "history_of_vomiting": { "type": "bool … (truncated) ``` ## Response schema (JSON Schema) ```json { "type": "json", "example": { "path": "/api/calc/pecarn_head", "count": 2, "items": [ { "formula": "pecarn_head", "age_band": "ge_2", "citation": { "id": "kuppermann-2009", "doi": "10.1016/S0140-6736(09)61558-0", "title": "Identification of children at very low risk of clinically-important brain injuries after head trauma: a prospective cohort study", "source": "Lancet. 2009;374(9696):1160-1170", "authors": "Kuppermann N, Holmes JF, Dayan PS, et al." }, "criteria": [ { "met": false, "factor": "gcs_le_14" }, { "met": false, "factor": "altered_mental_status" }, { "met": false, "factor": "signs_basilar_skull_fracture" }, { "met": false, "factor": "history_of_loc" }, { "met": false, "factor": "history_of_vomiting" }, { "met": false, "factor": "severe_headache" }, { "met": false, "factor": "severe_mechanism" } ], "age_years": 10, "risk_tier": "low", "disclaimer": "Not a medical device. Deterministic published-formula or published-code output for autonomous agents. A licensed clinician remains responsible for patient care and billing submissions.", "ct_recommended": false, "observation_vs_ct": false, "ct_not_recommended": true, "formula_expression": "high if any age-applicable high-risk factor, else intermediate if any age-applicable intermediate factor, else low; lt_2 tree if age < 2, ge_2 tree if age 2-17" }, { "formula": "pecarn_head", "age_band": "ge_2", "citation": { "id": "kuppermann-2009", "doi": "10.1016/S0140-6736(09)61558-0", "title": "Identification of children at very low risk of clinically-important brain injuries after head trauma: a prospective cohort study", "source": "Lancet. 2009;374(9696):1160-1170", "authors": "Kuppermann N, Holmes JF, Dayan PS, et al." }, "criteria": [ { "met": false, "factor": "gcs_le_14" }, { "met": false, "factor": "altered_mental_status" }, { "met": false, "factor": "signs_basilar_skull_fracture" }, { "met": false, "factor": "history_of_loc" }, { "met": false, "factor": "history_of_vomiting" }, { "met": false, "factor": "severe_headache" }, { "met": false, "factor": "severe_mechanism" … (truncated) ``` ## More - Live health (JSON, refreshed every minute): https://www.zero.xyz/c/pecarn-pediatric-head-ct-decision-rule-kuppermann-2009-ccc9ff27/health.json - [Zero catalog index](https://www.zero.xyz/llms.txt) - [Other services from api.magentlab.com](https://www.zero.xyz/host/api.magentlab.com/llms.txt)