ModifiedArizona Complete HealthPolicy CP.MP.190

Outpatient Oxygen Use

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Governs medical necessity criteria, reauthorization, exclusions, and coding for outpatient/home oxygen therapy and related oxygen delivery systems for pediatric and adult members/enrollees of the health plans affiliated with Centene Corporation (applies to Arizona Complete Health members as part of Centene policies).

Policy Summary

PayerArizona Complete Health

PolicyOutpatient Oxygen Use

Policy CodePolicy CP.MP.190

Change TypeCriteria revisions, coding addition, and administrative timing update

Effective Date

Next Review Date

Key ActionSubmit prior authorization with qualifying blood gas or pulse oximetry documentation and a physician evaluation within 90 days of recertification.

SourceLink

POLICY UPDATE CHANGES

Updated all criteria instances of 'blood gas study' to include 'or pulse oximetry measurement' and changed age thresholds from ≥21 to ≥18 for adults and <21 to <18 for pediatrics.

Edited portable oxygen criteria to include option for 'mobile within community' in addition to 'within the home' and reorganized portable oxygen criteria; added pediatric portable oxygen system criteria.

Added CPT/HCPCS code E0447 to the coding table (portable liquid oxygen contents).

Updated recertification timing in Criteria IV.A. from 30 days to 90 days prior to the date of recertification.

E0430–E0447HCPCS code examples

PaO2 ≤55 / SpO2 ≤88%Adult LTOT threshold

90Recert window (days)

18Age cutoff

E0447New code added

Coverage and Medical Necessity Criteria

Initial therapy — Adults (≥ 18 years)

Covered when ALL of the following are met

Adult initial approval: Physician-documented severe lung disease or hypoxemia-related symptoms that might be expected to improve with oxygen therapy

(Section I.A)

Adult qualifying blood gas or oximetry (Group I): Member qualifies for Group I by meeting at least one of: (a) an arterial PO2 ≤ 55 mm Hg or arterial oxygen saturation (or pulse oximetry) ≤ 88% at rest (awake) on room air; (b) an arterial PO2 ≤ 55 mm Hg or arterial oxygen saturation (or pulse oximetry) ≤ 88% taken during sleep for a beneficiary who demonstrates PO2 ≥ 56 mm Hg or oxygen saturation (or pulse oximetry) ≥ 89% while awake; (c) a decrease in arterial PO2 > 10 mm Hg or decrease in arterial oxygen saturation (or pulse oximetry) > 5% from baseline during sleep associated with symptoms/signs attributable to hypoxemia; (d) an arterial PO2 ≤ 55 mm Hg or arterial oxygen saturation (or pulse oximetry) ≤ 88% during exercise for a beneficiary who demonstrates PO2 ≥ 56 mm Hg or arterial oxygen saturation (or pulse oximetry) ≥ 89% at rest, with documentation that supplemental oxygen improves the exercise hypoxemiaGroup I thresholds

(Section I.B.1)

Adult Group II qualifying criteria: Member qualifies for Group II by meeting BOTH: (a) an arterial PO2 56–59 mm Hg or arterial oxygen saturation (or pulse oximetry) ≤ 89%; AND (b) one of dependent edema suggestive of congestive heart failure, pulmonary hypertension/cor pulmonale, or erythrocythemia with hematocrit > 56%Group II thresholds

(Section I.B.2)

Timing/setting of qualifying test: Qualifying blood gas study or pulse oximetry must be either: (1) performed during an inpatient stay and closest to but no earlier than 2 days before discharge; OR (2) performed when the treating practitioner noted signs/symptoms that can be relieved by home oxygen

(Section I.C)

Portable oxygen specific: If the request is for a portable oxygen system, the member must be mobile within the home or community, and the qualifying blood gas study or pulse oximetry measurement must have been performed while at rest (awake) or during exercise (measurements obtained only during sleep do not qualify for portable oxygen)

(Section I.D)

Initial therapy — Pediatrics (< 18 years)

Covered when ALL of the following are met

Pediatric clinical diagnosis: Physician-documented severe lung disease or hypoxemia-related symptoms that might be expected to improve with oxygen therapy; examples include chronic lung disease of prematurity, cystic fibrosis with severe chronic hypoxemia, acute pulmonary/respiratory disease with persistent hypoxic respiratory failure to facilitate safe earlier discharge, bronchopulmonary dysplasia with chronic hypoxemia, agenesis/hypoplasia/dysplasia of the lung, chronic cardiopulmonary disease (cor pulmonale), P pulmonale on EKG, pulmonary hypertension without congenital heart disease complicated by chronic hypoxemia, interstitial lung disease with severe chronic hypoxemia, and other causes of chronic hypoxemia

(Section II.A)

Pediatric oximetry/ABG thresholds: For children <1 year: one of (a) SpO2 ≤ 90% during 5% of the recording time; OR (b) three independent SpO2 measurements ≤ 90% if taken intermittently. For children ≥1 year: one of (a) SpO2 ≤ 93% during 5% of the recording time; OR (b) three independent SpO2 measurements ≤ 93% if taken intermittentlyPediatric thresholds

(Section II.B)

Portable oxygen pediatric mobility: If the request is for a portable oxygen system, the pediatric member must be mobile within the home or community

(Section II.C)

Reauthorization — Adults (≥ 18 years)

Reauthorization is covered when meeting the following

Physician evaluation: Evaluation by the treating physician within 90 days prior to the date of recertification90 days

(Section III.A)

Rationale for continued therapy: One of: (1) chronic hypoxemia is not expected to improve or is expected to worsen, documented in an explanatory letter of medical necessity; (2) treatment is for nocturnal hypoxemia in a member who qualifies for Group I and two oxygen requests have already been authorized; (3) a new arterial blood gas (ABG) or pulse oximetry documents continued fulfillment of initial criteria, obtained within required timeframes and by acceptable sources (for Group I measurement obtained within 90 days of recertification by physician/designee or IDTF; for Group II repeat ABG/oximetry obtained within 30 days of recertification)

(Section III.A.1-3)

Portable oxygen reauthorization: If the request is for a portable oxygen system, member must be mobile within the home or community AND the qualifying blood gas study or pulse oximetry measurement must have been performed while at rest (awake) or during exercise; measurements performed only during sleep do not qualify for portable oxygen

(Section III.B)

Reauthorization — Pediatrics (< 18 years)

Covered when ALL of the following are met

Physician evaluation pediatric: Evaluation by the treating physician within 90 days prior to the date of recertification90 days

(Section IV.A)

Pediatric reauth criteria: One of: (1) chronic hypoxemia is not expected to resolve or is expected to worsen, documented in an explanatory letter of medical necessity; OR (2) a new recorded pulse oximetry (overnight recommended), sleep study report, or blood gas result documents continued fulfillment of initial authorization criteria, with the measurement obtained within 30 days of the recertification date and obtained by the physician or designee or by an independent diagnostic testing facility (IDTF); O2 levels obtained by DME providers do not qualify30 days for tests

(Section IV.B)

Portable oxygen pediatric reauth mobility: If the request is for a portable oxygen system, the pediatric member must be mobile within the home or community

(Section IV.C)

Not medically necessary / Exclusions

Not medically necessary indications: Oxygen concentrators are not medically necessary for: angina pectoris in the absence of hypoxemia; breathlessness without cor pulmonale or evidence of hypoxemia; severe peripheral vascular disease causing local desaturation without systemic hypoxemia; shortness of breath or dyspnea in a pediatric patient without evidence of hypoxemia; and terminal illnesses that do not affect the ability to breathe.

(Section V)

Stationary oxygen for cluster headache

Covered when ALL of the following are met

Cluster headache diagnosis: Diagnosis of cluster headache evidenced by ALL of: (1) at least five severe unilateral headache attacks lasting 15–180 minutes when untreated; (2) headaches accompanied by at least one ipsilateral autonomic feature or a sense of restlessness/agitation (examples: conjunctival injection/lacrimation; nasal congestion/rhinorrhea; eyelid edema; forehead/facial sweating; miosis/ptosis; restlessness or agitation); and (3) attack frequency between one every other day and eight per day

(Section VI.A)

High-level coverage criteria and administrative rules

Covered when ALL of the following are met as specified in the detailed criteria sections:

Measurement methods and terminology: All references to 'blood gas study' in qualifying criteria have been updated to include 'or pulse oximetry measurement'; references to arterial oxygen saturation have been updated to include '(or pulse oximetry)'.

Applies to initial and recertification criteria.

Age definitions: Age thresholds revised: adult criteria apply to members ≥ 18 years; pediatric criteria apply to members < 18 years.

Replaces prior ≥21 / <21 cutoffs.

Portable oxygen mobility: Portable oxygen criteria expanded to require member mobility and now include 'mobile within the community' in addition to 'within the home'; pediatric portable oxygen system criteria were added.

See detailed portable oxygen sections for specifics.

Recertification timing: Recertification documentation (including physician evaluation) must be submitted within 90 days prior to the date of recertification.90 days

Updated from 30 days.

Cost-preference: If a medically necessary, lower-cost item exists and will meet the member's needs, a higher-cost item will be denied.

Applies to equipment selection decisions.

Oxygen concentrators are considered not medically necessary for conditions in which systemic hypoxemia is not documented. Examples explicitly listed in the policy include: angina pectoris in the absence of hypoxemia; breathlessness without cor pulmonale or evidence of hypoxemia; severe peripheral vascular disease with local desaturation but without systemic hypoxemia; shortness of breath or dyspnea in pediatric patients without evidence of hypoxemia; and terminal illnesses that do not affect the ability to breathe.

The policy text that previously referenced an alternative treatments clause (I.E.) has been removed and is no longer present in this document; there is no retained requirement or exception for alternative therapies in the current criteria language.

Refer to the exclusions list for explicit noncoverage: oxygen concentrators are not medically necessary for the non‑hypoxemic conditions enumerated in Section V, including angina without hypoxemia, breathlessness without cor pulmonale or evidence of hypoxemia, localized desaturation from peripheral vascular disease without systemic hypoxemia, pediatric dyspnea without hypoxemia, and terminal illnesses that do not impair breathing.

When selecting oxygen equipment, the policy applies a cost‑preference rule: if a medically necessary, lower‑cost item exists and will meet the member's clinical needs, a request for a higher‑cost device may be denied. This cost‑preference principle is used to determine equipment authorizations and denials.

HCPCS / CPT Codes and Clinical Thresholds

Oxygen system and contents HCPCS codesHCPCS

E0424	Stationary compressed gaseous oxygen system, rental; includes container, contents, regulator, flowmeter, humidifier, nebulizer, cannula or mask, and tubing.
E0425	Stationary compressed gas system, purchase; includes regulator, flowmeter, humidifier, nebulizer, cannula or mask, and tubing.
E0430	Portable gaseous oxygen system, purchase; includes regulator, flowmeter, humidifier, cannula or mask, and tubing.
E0431	Portable gaseous oxygen system, rental; includes portable container, regulator, flowmeter, humidifier, cannula or mask, and tubing.
E0433	Portable liquid oxygen system, rental; home liquefier used to fill portable liquid oxygen containers, includes portable containers, regulator, flowmeter, humidifier, cannula or mask and tubing, with or without supply reservoir and contents gauge.
E0434	Portable liquid oxygen system, rental; includes portable container, supply reservoir, humidifier, flowmeter, refill adaptor, contents gauge, cannula or mask, and tubing.
E0435	Portable liquid oxygen system, purchase; includes portable container, supply reservoir, flowmeter, humidifier, contents gauge, cannula or mask, tubing and refill adaptor.
E0439	Stationary liquid oxygen system, rental; includes container, contents, regulator, flowmeter, humidifier, nebulizer, cannula or mask, & tubing.
E0440	Stationary liquid oxygen system, purchase; includes use of reservoir, contents indicator, regulator, flowmeter, humidifier, nebulizer, cannula or mask, and tubing.
E0441	Stationary oxygen contents, gaseous, 1 month ' s supply = 1 unit.

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Oxygen concentrator and enrichment system codesHCPCS

E1390	Oxygen concentrator, single delivery port, capable of delivering 85 percent or greater oxygen concentration at the prescribed flow rate.
E1391	Oxygen concentrator, dual delivery port, capable of delivering 85 percent or greater oxygen concentration at the prescribed flow rate, each.
E1392	Portable oxygen concentrator, rental.
E1405	Oxygen and water vapor enriching system with heated delivery.
E1406	Oxygen and water vapor enriching system without heated delivery.

Additional oxygen system/rental and supplies codesHCPCS

K0738	Portable gaseous oxygen system, rental; home compressor used to fill portable oxygen cylinders; includes portable containers, regulator, flowmeter, humidifier, cannula or mask, and tubing.
S8120	Oxygen contents, gaseous, 1 unit equals 1 cubic foot.
S8121	Oxygen contents, liquid, 1 unit equals 1 pound.

Covered HCPCS codes (concentrators and contents)HCPCSCovered

E0447	Portable oxygen contents, liquid, 1 month's supply = 1 unit, prescribed amount at rest or nighttime exceeds 4 liters per minute (LPM).
E1390	Oxygen concentrator, single delivery port, capable of delivering 85 percent or greater oxygen concentration at the prescribed flow rate.
E1391	Oxygen concentrator, dual delivery port, capable of delivering 85 percent or greater oxygen concentration at the prescribed flow rate, each.
E1392	Portable oxygen concentrator, rental.
E1405	Oxygen and water vapor enriching system with heated delivery.

Other HCPCS/S codes (portable systems and contents)HCPCSCovered

E1406	Oxygen and water vapor enriching system without heated delivery.
K0738	Portable gaseous oxygen system, rental; home compressor used to fill portable oxygen cylinders; includes portable containers, regulator, flowmeter, humidifier, cannula or mask, and tubing.
S8120	Oxygen contents, gaseous, 1 unit equals 1 cubic foot.
S8121	Oxygen contents, liquid, 1 unit equals 1 pound.

Adult Group I thresholds — qualifying measurements

Resting threshold (Group I)PaO2 ≤ 55 mmHg or SpO2 ≤ 88% measured at rest (awake) breathing room air.

Sleep-based criteria (Group I)PaO2 ≤ 55 mmHg or SpO2 ≤ 88% during sleep for beneficiaries who demonstrate PaO2 ≥ 56 mmHg or SpO2 ≥ 89% while awake.

Exercise-based criteria (Group I)PaO2 ≤ 55 mmHg or SpO2 ≤ 88% during exercise for beneficiaries with daytime rest values ≥56 mmHg or SpO2 ≥89%; supplemental oxygen must improve the exercise hypoxemia.

Nocturnal desaturation delta (Group I)A decrease in PaO2 > 10 mmHg or a decrease in SpO2 > 5% from baseline during sleep when associated with attributable symptoms (e.g., cognitive impairment, nocturnal restlessness/insomnia).

Adult Group II thresholds — qualifying measurements and required findings

Numeric threshold (Group II)PaO2 56–59 mmHg or SpO2 ≤ 89% measured at rest, during sleep, or during exercise.

Required accompanying finding (one of) Dependent edema suggesting congestive heart failure.

Required accompanying finding (one of) Pulmonary hypertension or cor pulmonale confirmed by pulmonary artery pressure measurement, gated blood pool scan, echocardiogram, or P pulmonale on EKG.

Required accompanying finding (one of)Erythrocythemia with hematocrit > 56%.

Pediatric thresholds — recording-based and measurement criteria

Infants (< 1 year)SpO2 ≤ 90% during 5% of the recording time.

Infants alternative (intermittent)Three independent SpO2 measurements ≤ 90% if measurements are taken intermittently.

Children (≥ 1 year)SpO2 ≤ 93% during 5% of the recording time.

Children (≥ 1 year) alternative (intermittent)Three independent SpO2 measurements ≤ 93% if measurements are taken intermittently.

Prescribed flow rate threshold — coding implication for E0447

E0447 coding conditionE0447 applies when portable oxygen contents (liquid), 1 month's supply = 1 unit, and the prescribed amount at rest or nighttime exceeds 4 liters per minute (LPM).

ApplicabilityThreshold specifically identifies prescribed flow rate exceeding 4 LPM as the criterion for E0447 coding.

Documentation implicationPrescriptions or orders must indicate the prescribed flow rate at rest or nighttime to justify E0447.

Prior Authorization, Documentation, and Billing Guidance

Denial Risk

Portable oxygen denial rule

If the only qualifying blood gas study or pulse oximetry measurement was performed during sleep, portable oxygen will be denied as not reasonable and necessary.

Portable oxygen requests require the qualifying measurement to be obtained while the member is awake (rest) or during exercise; sleep-only qualifying measurements are not acceptable.

Denial Risk

Cost-effective alternative denial risk

If a medically necessary, lower-cost item exists and will suit the member's medical needs, a higher-cost item will be denied.

Cost-preference enforcement applies when a less expensive medically appropriate alternative is available.
Providers should document why a higher-cost item is required if no suitable lower-cost alternative exists.

Clinical Background and Definitions

Oxygen therapy is the administration of oxygen at concentrations greater than ambient air to treat or prevent manifestations of hypoxemia. Hypoxemia can result from hypoventilation, ventilation–perfusion mismatch, shunt, diffusion limitation, or low inspired oxygen and is documented using arterial blood gas measurements (PaO2) or pulse oximetry (SpO2). Continuous home oxygen therapy, or long‑term oxygen therapy (LTOT), is intended for patients with chronic lung disease who meet specified laboratory thresholds (for example, PaO2 ≤ 55 mmHg or SpO2 ≤ 88% at rest) and has demonstrated benefit for appropriately selected hypoxemic patients.

Oxygen therapy — definition

Basic definitionAdministration of oxygen at concentrations greater than ambient air (20.9%) to treat or prevent symptoms and manifestations of hypoxemia.

IntentDelivered with the intent to treat or prevent hypoxemia-related symptoms and manifestations.

ScopeIncludes any therapy that increases inspired oxygen fraction above ambient levels for clinical benefit.

Long-term oxygen therapy (LTOT) — definition and qualifying thresholds

Definition (LTOT)Continuous home oxygen therapy for chronic lung disease patients who meet laboratory thresholds such as PaO2 ≤ 55 mmHg or SpO2 ≤ 88% (Group I) or PaO2 ≤59 mmHg/SpO2 ≤89% with cor pulmonale/erythrocythemia (Group II).

Examples of qualifying lab thresholdsResting PaO2 ≤ 55 mmHg or SpO2 ≤ 88%; PaO2 56–59 mmHg or SpO2 ≤ 89% with cor pulmonale, right heart failure, or hematocrit/erythrocythemia.

Other qualifying contextsLTOT may also be indicated for PaO2 ≤ 55 mmHg or SpO2 ≤ 88% during exercise or sleep when documented.

Hypoxemia — terminology and acceptable measurements

Terminology updatePolicy replaces earlier uses of 'hypoxia' with 'hypoxemia' throughout the document.

Acceptable measurementsQualifying measurements may be arterial blood gas (PaO2) or pulse oximetry (SpO2); the policy updated 'blood gas study' references to include 'or pulse oximetry measurement'.

Measurement contextsMeasurements used for qualification can be obtained at rest (awake), during sleep, or during exercise as specified in the Group I/II and pediatric criteria.

Policy Summary

PayerArizona Complete Health

PolicyOutpatient Oxygen Use

Policy CodePolicy CP.MP.190

Change TypeCriteria revisions, coding addition, and administrative timing update

Effective Date

Next Review Date

Key ActionSubmit prior authorization with qualifying blood gas or pulse oximetry documentation and a physician evaluation within 90 days of recertification.

SourceLink

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Outpatient Oxygen Use

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Sign up for Arizona Complete Health Policy CP.MP.190 alerts

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Coverage and Medical Necessity Criteria

Initial therapy — Adults (≥ 18 years)

Covered when ALL of the following are met

Adult initial approval: Physician-documented severe lung disease or hypoxemia-related symptoms that might be expected to improve with oxygen therapy

(Section I.A)

(Section I.B.1)

(Section I.B.2)

(Section I.C)

(Section I.D)

Initial therapy — Pediatrics (< 18 years)

Covered when ALL of the following are met

(Section II.A)

(Section II.B)

Portable oxygen pediatric mobility: If the request is for a portable oxygen system, the pediatric member must be mobile within the home or community

(Section II.C)

Reauthorization — Adults (≥ 18 years)

Reauthorization is covered when meeting the following

Physician evaluation: Evaluation by the treating physician within 90 days prior to the date of recertification90 days

(Section III.A)

(Section III.A.1-3)

(Section III.B)

Reauthorization — Pediatrics (< 18 years)

Covered when ALL of the following are met

Physician evaluation pediatric: Evaluation by the treating physician within 90 days prior to the date of recertification90 days

(Section IV.A)

(Section IV.B)

Portable oxygen pediatric reauth mobility: If the request is for a portable oxygen system, the pediatric member must be mobile within the home or community

(Section IV.C)

Not medically necessary / Exclusions

(Section V)

Stationary oxygen for cluster headache

Covered when ALL of the following are met

(Section VI.A)

High-level coverage criteria and administrative rules

Covered when ALL of the following are met as specified in the detailed criteria sections:

Applies to initial and recertification criteria.

Age definitions: Age thresholds revised: adult criteria apply to members ≥ 18 years; pediatric criteria apply to members < 18 years.

Replaces prior ≥21 / <21 cutoffs.

See detailed portable oxygen sections for specifics.

Recertification timing: Recertification documentation (including physician evaluation) must be submitted within 90 days prior to the date of recertification.90 days

Updated from 30 days.

Cost-preference: If a medically necessary, lower-cost item exists and will meet the member's needs, a higher-cost item will be denied.

Applies to equipment selection decisions.

HCPCS / CPT Codes and Clinical Thresholds

Oxygen system and contents HCPCS codesHCPCS

E0424	Stationary compressed gaseous oxygen system, rental; includes container, contents, regulator, flowmeter, humidifier, nebulizer, cannula or mask, and tubing.
E0425	Stationary compressed gas system, purchase; includes regulator, flowmeter, humidifier, nebulizer, cannula or mask, and tubing.
E0430	Portable gaseous oxygen system, purchase; includes regulator, flowmeter, humidifier, cannula or mask, and tubing.
E0431	Portable gaseous oxygen system, rental; includes portable container, regulator, flowmeter, humidifier, cannula or mask, and tubing.
E0433	Portable liquid oxygen system, rental; home liquefier used to fill portable liquid oxygen containers, includes portable containers, regulator, flowmeter, humidifier, cannula or mask and tubing, with or without supply reservoir and contents gauge.
E0434	Portable liquid oxygen system, rental; includes portable container, supply reservoir, humidifier, flowmeter, refill adaptor, contents gauge, cannula or mask, and tubing.
E0435	Portable liquid oxygen system, purchase; includes portable container, supply reservoir, flowmeter, humidifier, contents gauge, cannula or mask, tubing and refill adaptor.
E0439	Stationary liquid oxygen system, rental; includes container, contents, regulator, flowmeter, humidifier, nebulizer, cannula or mask, & tubing.
E0440	Stationary liquid oxygen system, purchase; includes use of reservoir, contents indicator, regulator, flowmeter, humidifier, nebulizer, cannula or mask, and tubing.
E0441	Stationary oxygen contents, gaseous, 1 month ' s supply = 1 unit.

1–10 of 15

1/2

Oxygen concentrator and enrichment system codesHCPCS

E1390	Oxygen concentrator, single delivery port, capable of delivering 85 percent or greater oxygen concentration at the prescribed flow rate.
E1391	Oxygen concentrator, dual delivery port, capable of delivering 85 percent or greater oxygen concentration at the prescribed flow rate, each.
E1392	Portable oxygen concentrator, rental.
E1405	Oxygen and water vapor enriching system with heated delivery.
E1406	Oxygen and water vapor enriching system without heated delivery.

Additional oxygen system/rental and supplies codesHCPCS

K0738	Portable gaseous oxygen system, rental; home compressor used to fill portable oxygen cylinders; includes portable containers, regulator, flowmeter, humidifier, cannula or mask, and tubing.
S8120	Oxygen contents, gaseous, 1 unit equals 1 cubic foot.
S8121	Oxygen contents, liquid, 1 unit equals 1 pound.

Covered HCPCS codes (concentrators and contents)HCPCSCovered

E0447	Portable oxygen contents, liquid, 1 month's supply = 1 unit, prescribed amount at rest or nighttime exceeds 4 liters per minute (LPM).
E1390	Oxygen concentrator, single delivery port, capable of delivering 85 percent or greater oxygen concentration at the prescribed flow rate.
E1391	Oxygen concentrator, dual delivery port, capable of delivering 85 percent or greater oxygen concentration at the prescribed flow rate, each.
E1392	Portable oxygen concentrator, rental.
E1405	Oxygen and water vapor enriching system with heated delivery.

Other HCPCS/S codes (portable systems and contents)HCPCSCovered

E1406	Oxygen and water vapor enriching system without heated delivery.
K0738	Portable gaseous oxygen system, rental; home compressor used to fill portable oxygen cylinders; includes portable containers, regulator, flowmeter, humidifier, cannula or mask, and tubing.
S8120	Oxygen contents, gaseous, 1 unit equals 1 cubic foot.
S8121	Oxygen contents, liquid, 1 unit equals 1 pound.