A0424 Extra Ambulance Attendant HCPCS Reimbursement | OpenPayer

Summary & Overview

HCPCS A0424: Extra Ambulance Attendant for Ground or Air Transport

HCPCS Level II code A0424 denotes an extra ambulance attendant assigned to a transport team for ground (ALS or BLS) or air (fixed- or rotary-wing) conveyance. The code is used when an additional qualified attendant is required to deliver hands-on clinical care or monitoring during transit and typically requires medical review. Nationally, this code matters for emergency medical services billing, staffing costs, and payer medical necessity determinations for enhanced transport resources. Key payers addressed in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare.

Readers will learn what A0424 represents in clinical and billing terms, typical sites of service, and how payers approach coverage and review for extra attendant claims. The publication provides benchmarks for utilization and reimbursement where available, summarizes common payer policy themes and review triggers, and outlines the clinical contexts that commonly prompt use of the code (for example, higher-acuity patients requiring additional hands-on care during transport). Data not available in the input will be noted as such in relevant sections.

AetnaBlue Cross Blue ShieldCigna HealthUnitedHealthcareMedicareA0424HCPCS Level IIambulancemedical transportemergency medical servicesextra attendantair ambulanceground ambulance

Billing Code Overview

HCPCS Level II code A0424 describes an extra ambulance attendant provided during ground or air transport. The code applies when an additional trained attendant is required beyond the standard ambulance crew for either advanced life support (ALS) or basic life support (BLS) on ground transport, or for fixed-wing or rotary-wing air transport. The service type is emergency or non-emergency ambulance support staffing to provide hands-on clinical care or monitoring during patient transport. The typical site of service is ambulance transport (ground or air) while in transit between locations.

Clinical & Coding Specifications

Clinical Context

A ground ambulance responds to an interfacility transfer of a critically ill adult patient from a rural hospital to a tertiary care center for advanced cardiothoracic care. The patient is intubated, mechanically ventilated, and requires continuous vasoactive infusions and invasive monitoring. The sending facility requests an additional trained ambulance attendant to accompany the patient to manage the ventilator, titrate vasopressors, and assist with advanced airway or invasive line troubleshooting en route. The ambulance team documents the patient’s condition, the reason for the extra attendant, the qualifications of the attendant (paramedic or critical care flight/transport nurse), and the medical necessity for a second clinician. The billing claim for the transport includes A0424 to reflect the extra attendant service, with supporting clinical notes and transport records submitted for medical review.

Coding Specifications

Modifier	Description	When to Use
`22`	Increased procedural services	Use when the presence of an extra attendant significantly increases complexity of the transport beyond usual ambulance service, with documentation of why complexity is greater.
`23`

Related Codes

HCPCS-A0425-GROUND-MILEAGE-PER-MILE

HCPCS A0425: Ground Mileage, Per Statute Mile

HCPCS-A0380-BLS-MILEAGE-PER-MILE

HCPCS A0380: BLS Mileage (Per Mile)

HCPCS-A0130-WHEELCHAIR-VAN-NON-EMERGENCY-TRANSPORTATION

HCPCS Level II A0130: Non-Emergency Wheelchair Van Transport

HCPCS-A0436-ROTARY-WING-AIR-MILEAGE

HCPCS A0436: Rotary Wing Air Mileage, Per Statute Mile

HCPCS-A0392-ALS-DEFIBRILLATION-DISPOSABLE-SUPPLIES

HCPCS A0392: ALS Defibrillation Disposable Supplies

HCPCS-A0888-NONCOVERED-AMBULANCE-MILEAGE-PER-MILE

HCPCS Level II A0888: Noncovered Ambulance Mileage, Per Mile

HCPCS-A0140-NON-EMERGENCY-AIR-TRANSPORTATION

HCPCS A0140: Non-Emergency Air Transportation (Private or Commercial)

HCPCS-A0021-AMBULANCE-SERVICE-OUTSIDE-STATE-PER-MILE-TRANSPORT

HCPCS A0021: Ambulance Service Outside State, Per-Mile Transport

HCPCS-A0394-ALS-DISPOSABLE-SUPPLIES-IV-DRUG-THERAPY

HCPCS A0394: ALS Specialized Disposable Supplies for IV Drug Therapy

HCPCS-A0390-ALS-MILEAGE-PER-MILE

HCPCS A0390: ALS mileage (per mile)

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Taxonomy Code	Specialty	Notes
`348000000X`	Emergency Medical Services (EMS) Practitioner	Typical provider specialty for ground ambulance personnel including paramedics and EMTs.
`364S00000X`	Critical Care Transport	Specialty taxonomy used by providers specializing in interfacility critical care transport.
`1835P0207X`	Paramedic	Individual clinician taxonomy for credentialed paramedics who often serve as extra attendants.
`363A00000X`	Flight Nurse	For air transport extra attendants who are registered nurses specializing in aeromedical transport.
`207Q00000X`	Anesthesiology	Occasionally involved when airway/ventilator care requires anesthesiology-level oversight during transport.

Related Diagnoses

ICD-10 Code	Description	Clinical Relevance
`I21.9`	Acute myocardial infarction, unspecified	Patients with recent infarction may require critical care transport and an extra attendant for hemodynamic support.
`I46.9`	Cardiac arrest, cause unspecified	Post-resuscitation patients often require advanced airway and hemodynamic management during transfer.
`J96.00`	Acute respiratory failure, unspecified whether with hypoxia or hypercapnia	Mechanical ventilation management during transport commonly necessitates an extra attendant.
`R57.9`	Shock, unspecified	Hemodynamically unstable patients on vasopressors need additional clinical staff during transport.
`T81.4XXA`	Infection following a procedure, initial encounter	Complex post-procedure patients requiring monitored transfer may need an extra attendant.
`G40.909`	Epilepsy, unspecified, not intractable, without status epilepticus	Patients with uncontrolled seizures may require additional personnel for airway protection and monitoring during transport.
`S06.5X9A`	Traumatic subdural hemorrhage with loss of consciousness of unspecified duration, initial encounter	Neurocritical patients often require extra staff for intracranial pressure monitoring, ventilation, and neurologic checks during transfer.

Related CPT Codes

CPT Code	Description	Relationship to This Procedure
`36556`	Insertion of non-tunneled centrally inserted central venous catheter, older than 5 years; without subcutaneous port or pump	May have been performed prior to or during patient stabilization before transfer; presence of central access often necessitates advanced monitoring during transport.
`36561`	Insertion of tunneled central venous catheter, without subcutaneous port or pump	Relevant for patients with long-term central access requiring careful management during transport.
`31500`	Intubation, endotracheal, emergency procedure	Patients transported with an endotracheal tube often require an extra attendant to manage airway and ventilator during transfer.
`94002`	Ventilator management, initiation of pressure/volume settings (e.g., in a transport setting) — note: billers commonly use transport-specific ventilator management codes where allowed	Extra attendant may be needed to manage mechanical ventilation during transport; this CPT represents ventilator-related services in peri-transfer scenarios.
`99091`	Collection and interpretation of physiologic data (e.g., ECG, blood pressure), digitally stored and/or transmitted by the patient and/or caregiver to the physician	Monitoring and management of continuous physiologic data during transport may be part of the extra attendant’s responsibilities.