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Billing 101 for Hyperbaric Providers

Billing 101 for Hyperbaric Providers

Billing 101 for Hyperbaric Providers


Understanding the ins and outs of hyperbaric coding, billing and reimbursement are challenging at best. The potential for financial loss is a game-changer and can no longer be viewed by providers as "That's not my concern" or "That's not my responsibility." Simple mistakes such as reversing the order of the diagnosis codes, using an unspecified diagnosis code or omitting the required second diagnosis code can lead to substantial financial losses. Many of the elective hyperbaric protocols recommend 20-40 hyperbaric treatments. An incorrect diagnosis code could translate into a loss averaging $11,000-$22,000 for a Medicare patient. 

The following information is a snapshot of hyperbaric coding and billing essentials that every provider should know and access regularly to ensure that expedient and maximum reimbursement is achieved. 


Unique Specialty Code for Physicians who specialize in Undersea and Hyperbaric Medicine

  • Physicians who specialize in Undersea and Hyperbaric Medicine have been assigned a unique specialty code by the Centers for Medicare and Medicaid Services (CMS). That specialty code is D4. The code went into effect on January 1, 2019.[1]

HCPCS/ CPT® Guidance

CPT code 99183 and HCPCS code G0277 are commonly utilized in hyperbaric oxygen therapy (HBOT). CPT code 99183 refers to providers' HBOT services and HCPCS code G0277 represents the facility component of the hyperbaric treatment. Table 1 below summarizes important details of these two codes, including:  

  • Payment Status Indicator: An OPPS payment status indicator is assigned to every HCPCS code. The status indicator identifies whether the service described by the HCPCS code is paid under the OPPS and if so, whether payment is made separately or packaged. The status indicator may also provide additional information about how the code is paid under the OPPS or under another payment system or fee schedule. [2][3]        
  • Global days: indicates if the global concept is applicable to the service. See topic "Global Surgical Transfer of Care to the Wound Clinic"

Table 1. CPT/ HCPCS Codes used in Hyperbaric Oxygen Therapy (HBOT). OPPS: Outpatient Prospective Payment System, MAC: Medicare Administrative Contractor, APC: Ambulatory Payment Classification

CodesDescriptionPayment Status IndicatorOPPS Payment StatusGlobal Days

Physician or other qualified health care professional attendance and supervision of hyperbaric oxygen therapy, per session. For the supervision of hyperbaric oxygen therapy, providers will bill one (1) increment of 99183 for each HBOT treatment. 

(B) This code is not recognized by OPPS when submitted on an outpatient hospital Part B bill type (12x and 13x).
  • Not paid under OPPS.
  • May be paid by fiscal intermediaries/MACs when submitted on a different bill type
The global concept does not apply

Hyperbaric oxygen under pressure, full body chamber, per 30-minute interval

(S) Significant Procedure, Not Discounted when Multiple

Paid under OPPS; separate APC payment.

The global concept does not apply

HCPCS Code G0277: Units of HBOT

  • In calculating how many 30-minute intervals to report, hospitals should take into consideration the time spent under pressure during descent, air-breaks, and ascent. 
  • Additional units may be billed for sessions requiring at least 16 minutes of the next 30-minute interval. For example, two units of HCPCS code G0277 should be billed for a session in duration of between 46 and 75 minutes, while three units should be billed for a session in duration of between 76 and 105 minutes. Further, four units of HCPCS code G0277 should be billed for a session in duration of between 106 and 135 minutes. 
  • HBO is typically prescribed for an average of 90 minutes, which hospitals should report using appropriate units of HCPCS code G0277 in order to properly bill for full body HBO therapy. In general, the Centers for Medicare and Medicaid Services (CMS) does not expect that a physician order for 90 minutes of HBO therapy would exceed four billed units of HCPCS code G0277. 
46 - 75
76 - 105
106 - 135
136 -165
166 - 195
196 - 225
226 - 255
256 - 285
286 - 315 *
316 - 345 *
346 - 375 *
376 - 405 *
406 - 435 *

* Navy Table IV with extensions 

Clarification on "Incident To" and "Direct Supervision" (CPT Code 99183)

  • HBOT is considered “incident to physician service” and requires Direct Supervision. The physicians or Qualified health providers will be billing 99183, and this requires Direct Supervision.  Direct Supervision per CMS definition "the physician is physically present on-site and is immediately available to furnish assistance and direction throughout the performance of the procedure. However, it does not mean the physician must be present in the same room when the procedure is being performed." [4]
  • In the Provider based department (PBD) or hospital outpatient department (HOPD), if a provider bills 99183, for the supervision of HBOT, there must also be facility fee G0277 billed. 

HBOT Diagnoses and ICD-10 Coding

The Centers for Medicare and Medicaid (CMS) Program reimbursement for HBOT will be limited to that which is administered in a chamber (including the one man unit) and is limited to the following conditions [5]:

  • Acute carbon monoxide intoxication,
  • Decompression illness,
  • Gas embolism,
  • Gas gangrene,
  • Acute traumatic peripheral ischemia. HBO therapy is a valuable adjunctive treatment to be used in combination with accepted standard therapeutic measures when loss of function, limb, or life is threatened.
  • Crush injuries and suturing of severed limbs. As in the previous conditions, HBO therapy would be an adjunctive treatment when loss of function, limb, or life is threatened.
  • Progressive necrotizing infections (necrotizing fasciitis),
  • Acute peripheral arterial insufficiency,
  • Preparation and preservation of compromised skin grafts (not for primary management of wounds),
  • Chronic refractory osteomyelitis, unresponsive to conventional medical and surgical management,
  • Osteoradionecrosis as an adjunct to conventional treatment,
  • Soft tissue radionecrosis as an adjunct to conventional treatment,
  • Cyanide poisoning,
  • Actinomycosis, only as an adjunct to conventional therapy when the disease process is refractory to antibiotics and surgical treatment,
  • Diabetic wounds of the lower extremities in patients who meet the following three criteria:
    • Patient has type I or type II diabetes and has a lower extremity wound that is due to diabetes;
    • Patient has a wound classified as Wagner grade III or higher; and
    •  Patient has failed an adequate course of standard wound therapy. 

The Undersea and Hyperbaric Medical Society (UHMS) recognizes the additional indications: 

  • Acute Thermal Burn Injury
  • Central Retinal Artery Occlusion
  • Idiopathic Sudden Sensorineural Hearing Loss

See topic "HBO Treatment Indications With Protocols" for more information. 

Single and Dual Diagnosis codes 

Single Diagnosis codes mean that one ICD-10 code from the accepted CMS list from National Coverage Determination (NCD) 20.29 will meet medical necessity for hyperbaric payment. 

Example, Chronic Refractory Osteomyelitis of the right foot. One code from the following list would meet medical necessity billing requirements. 

  • M86.371 Chronic Multifocal Osteomyelitis right ankle and foot 
  • M86.471 Chronic osteomyelitis with draining sinus, right ankle and foot
  • M86.571 Other chronic hematogenous osteomyelitis, right ankle and foot
  • M86.671 Other chronic osteomyelitis, right ankle and foot

Dual Diagnosis codes mean that two ICD-10 codes from the accepted CMS list from National Coverage Determination (NCD) 20.29 will meet medical necessity for hyperbaric payment IF used in the appropriate order.

Example, Wagner Grade 3 Type 2 Diabetic ulcer of the right heel involving necrosis of bone would be coded as follows:

  • E11.621-Type 2 Diabetes Mellitus with foot ulcer
  • L97.414 Non-pressure chronic ulcer of right heel and midfoot with necrosis of bone
  • For the DFU, always code the Diabetic code (E code) first followed by the ulcer code

Example, Soft tissue radiation injury to the bladder with hematuria

  • L59.8 Other disorder of the skin and subcutaneous tissue related to radiation (STRN)
  • N30.41 Radiation Cystitis with hematuria (STRN)
  • For Soft Tissue Radiation Injury, code the radiation first (L59.8) followed by the anatomical location of the radiation.

Additional Tips

  • Unspecified ICD-10 codes will not meet medical necessity for HBOT. For example, Chronic Refractory Osteomyelitis of the right foot would not meet medical necessity if billed as M86.579 - Other chronic hematogenous osteomyelitis, unspecified ankle and foot 
  • Ensure that every HBO treatment progress note contains the correct diagnosis established at the consultation. See topic "Documentation: HBO Progress Note".
  • Refer to the topic  "HBOT ICD-10" for the Undersea and Hyperbaric Medical Society (UHMS) Accepted indications. Keep the crosswalk accessible on your desk top and refer to it before completing your documentation
  • Communicate with other HBOT providers to ensure continuity of the diagnosis. Often times, the diagnosis is changed or altered when a different provider supervises HBOT leading to insurance denials.

Evaluation and Management Billed with HBOT

When is it Ok to bill an e/m with a procedure? Under both the Center for Medicare & Medicaid Services (CMS) and CPT® guidelines, an Evaluation and Management (E/M) service may be separately billed with a minor procedure as long as the E/M service was clearly documented and substantiated and modifier 25 - "Significant, separately identifiable evaluation and management service by the same physician on the same day of the procedure or other service" - is properly appended to the appropriate E/M service code. [6]

  • Seldom should there be a situation in which providers charge an E/M with HBOT. The CPT® code 99183 includes the evaluation and management necessary for daily HBOT supervision which would include the patient's pre-treatment evaluation, response to treatment and post-treatment evaluation. When CPT® 99183 is billed, CMS includes within the payment, the evaluation and management of the patient.
  • Occasionally, a situation may arise when an E/M code may be billed with HBOT. For instance, the patient arrives for HBOT and has developed new cellulitis of the foot or has a new wound due bumping his/her leg on a table prior to the appointment. The provider now has a separately identifiable problem to evaluate and treat. The provider may bill and e/m with the 99183. A 25 modifier must be appended to the E/M code to receive additional payment for the work provided. 

Other Procedures Billed with HBOT 

  • No payment adjustment rules for multiple procedures apply. Providers may charge for the procedures they perform in combination with HBOT. For example, the provider performs sharp wound debridement involving the skin and subcutaneous tissue 18 sq cm on the day of HBOT. The provider may bill 99183 and 11042 together and receive full payment for each.


HBOT coding and billing are two of the most critical components in any medical practice. Accuracy in both of these areas is essential to the revenue cycle and efficient operations. Providers should be directly involved and commit to learning the billing process. A center that fails to code and bill correctly, may see its doors close.  

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NOTE: This is a controlled document. This document is not a substitute for proper training, experience, and exercising of professional judgment. While every effort has been made to ensure the accuracy of the contents, neither the authors nor the Wound Reference, Inc. give any guarantee as to the accuracy of the information contained in them nor accept any liability, with respect to loss, damage, injury or expense arising from any such errors or omissions in the contents of the work.


  1. UHMS. Undersea and Hyperbaric Medical Society .;.
  2. . CMS Addendum D1 Proposed Payment Status Indicators .;.
  3. Centers for Medicare and Medicaid Services . Medicare Claims Processing Manual. Chapter 4 - Part B Hospital (Including Inpatient Hospital Part B and OPPS) . 2019;.
  4. . Today’s Wound Clinic, May 2017, Direct Supervision in the Provider-Based Department: What’s Required? Page 6 by Kathleen Schaum, MS .;.
  5. CMS. National Coverage Determination (NCD) for Hyperbaric Oxygen Therapy (20.29) . 2017;.
  6. DEPARTMENT OF HEALTH AND HUMAN SERVICES Centers for Medicare & Medicaid Services . Evaluation and Management Services . 2017;.
Topic 1426 Version 1.0