Summary & Overview

CPT 94645: Prolonged Inhalation Aerosol Therapy for Acute Airway Obstruction

CPT code 94645 represents each additional hour of continued inhalation aerosol therapy with medication used to treat acute airway obstruction. This code captures prolonged respiratory treatment time beyond the initial administration period and is used in settings where continuous aerosolized medication is required to address severe bronchospasm or other obstructive airway emergencies. Nationally, accurate use of this code affects resource tracking, billing clarity, and payment for extended respiratory care.

Key payers addressed in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find an overview of clinical context for prolonged inhalation aerosol therapy, typical sites of service where the code applies, and the billing considerations tied to reporting additional hours of treatment. The report outlines common modifiers and administrative elements associated with extended procedures, summarizes typical documentation expectations, and highlights how this code integrates with respiratory service lines.

This publication provides benchmarks and policy-relevant context for healthcare administrators, coding professionals, and clinicians responsible for respiratory care billing, helping them understand where CPT code 94645 fits within prolonged airway management workflows and payer interactions.

AetnaBlue Cross Blue ShieldCigna HealthUnitedHealthcareMedicareCPT 94645inhalation aerosol therapyacute airway obstructionprolonged respiratory careemergency respiratory treatmentprocedure codingbilling guidance

Billing Code Overview

CPT code 94645 describes continued administration of an inhalation aerosol treatment with medication for greater than an hour to treat acute airway obstruction. The code is reported for each additional hour of treatment beyond the initial administration period.

Service type: Prolonged inhalation aerosol therapy for acute airway obstruction
Typical site of service: Emergency department or inpatient setting where continuous inhalation therapy for acute airway obstruction is provided

Data not available in the input.

Clinical & Coding Specifications

Clinical Context

A typical patient is an adult with acute bronchospasm from asthma or chronic obstructive pulmonary disease (COPD) presenting to the emergency department or inpatient unit with progressive respiratory distress despite initial nebulized therapy. The patient arrives tachypneic with audible wheeze, increased work of breathing, and oxygen saturation trending downward on room air. Initial management includes assessment, supplemental oxygen, continuous monitoring, and administration of inhaled bronchodilator therapy (eg, nebulized albuterol with or without ipratropium). When improvement is incomplete and the treating clinician determines that prolonged continuous aerosolized bronchodilator therapy is required to reverse acute airway obstruction, the provider initiates or continues inhalation aerosol treatment beyond the first hour and documents ongoing medication delivery and clinical response.

Workflow steps:

Triage and initial assessment, vital signs, pulse oximetry, and focused respiratory exam.
Initiation of standard nebulized bronchodilator(s) with documentation of response over the first 30–60 minutes.
Decision to continue continuous nebulization for an additional hour due to persistent bronchospasm or worsening airflow obstruction; initiation of continuous aerosol delivery and documentation of medication, rate, and monitoring.
Ongoing reassessment during the additional hour(s) including respiratory status, oxygenation, heart rate, and response to therapy; documentation supports use of 94645 for each additional hour of continuous inhalation aerosol therapy for acute airway obstruction.
Transition to intermittent therapy, escalation to noninvasive ventilation, or admission to an observation or inpatient bed depending on response.

Typical site of service: Emergency department, observation unit, hospital inpatient unit, or intensive care unit.

Coding Specifications

Modifier	Description	When to Use
`25`	Significant, separately identifiable evaluation and management service by the same physician on the same day of the procedure	Use when a distinct E/M visit is provided on the same day as `94645` and properly documented (eg, initial ED evaluation leading to decision for continuous nebulization).
`52`	Reduced services	Use when a continuous inhalation session is partially reduced or discontinued and documentation supports billing at a reduced level.
`53`	Discontinued procedure	Use when continuous aerosol therapy is started but discontinued due to patient condition (eg, intolerance) before the intended hour is completed.
`59`	Distinct procedural service	Use when another procedure on the same day is unrelated anatomically or by session to the continuous inhalation therapy and requires separation.
`76`	Repeat procedure or service by same provider	Use when the same provider repeats continuous inhalation aerosol treatment after an earlier session on the same day.
`78`	Unplanned return to the operating/procedure room by the same physician following initial procedure	Rare for `94645` but used if an unplanned return to a monitored procedure area for additional continuous aerosol therapy is required after initial completion.
`22`	Increased procedural services	Use when the continuous therapy requires substantially greater resources or time beyond typical expectations and documentation supports the increased work.
`23`	Unusual anesthesia	Use if unusual anesthesia/analgesia is required during the aerosol therapy, documented separately.
`24`	Unrelated E/M by same physician during postoperative period	Not common but applicable when an unrelated E/M occurs during a postoperative period for another surgery and continuous aerosol is provided—documentation must support unrelatedness.
`25`	Significant, separately identifiable E/M service by the same physician (listed twice intentionally above as highly applicable)	See first entry—used for distinct E/M on same day.

Taxonomy Code	Specialty	Notes
`207RC0000X`	Pulmonology	Pulmonologists commonly oversee severe airway obstruction and continuous aerosol therapies in inpatient settings.
`2084P0800X`	Emergency Medicine	Emergency physicians frequently initiate and manage continuous nebulization in the ED.
`208D00000X`	Critical Care Medicine	Intensivists manage continuous aerosol therapy in the ICU for severe exacerbations.
`207L00000X`	Allergy & Immunology	Allergy specialists may manage severe asthma exacerbations requiring prolonged inhalation therapy.
`207K00000X`	Family Medicine	Hospitalist or family medicine physicians may provide and bill for this therapy when caring for admitted patients.

ICD-10 Code	Description	Clinical Relevance
`J45.901`	Unspecified asthma, uncomplicated	Acute asthma exacerbations often cause bronchospasm requiring continuous nebulized bronchodilator therapy.
`J44.1`	Chronic obstructive pulmonary disease with (acute) exacerbation	COPD exacerbations with significant airflow obstruction may require prolonged inhalation aerosol treatment.
`J96.00`	Acute respiratory failure, unspecified whether with hypoxia or hypercapnia	Severe airway obstruction refractory to initial therapy can progress to respiratory failure needing ongoing aerosol management and advanced support.
`R06.2`	Wheezing	Symptom code commonly documented when bronchospasm prompts continuous inhalation therapy.
`J98.01`	Acute bronchospasm	Direct indication for continuous aerosolized bronchodilator therapy to relieve bronchospasm.

CPT Code	Description	Relationship to This Procedure
`94640`	Pressurized or non-pressurized inhalation treatment for acute airway obstruction; initial nebulizer treatment	Often billed for the initial nebulized treatment session prior to continuing to additional hours billed with `94645`.
`94644`	Continuous inhalation treatment for acute airway obstruction; first hour	Represents the first hour of continuous inhalation aerosol therapy; `94645` is used for each additional hour beyond the first.
`94664`	Demonstration and/or evaluation of patient utilization of an aerosol generator, nebulizer, metered dose inhaler or IPPB device	May be provided for patient education on device use during or after acute therapy.
`99281`–`99285`	Emergency department evaluation and management services, levels 1–5	An ED E/M code is reported for the initial evaluation that led to initiation of continuous inhalation therapy; use of `25` modifier may be required if billed same day as `94644`/`94645`.
`31500`	Intubation, endotracheal, emergency procedure	Performed if airway compromise progresses and invasive airway management is required after or during attempted continuous aerosol therapy.

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