- Who Governs and Who Tests: BNACB and NBDHMT
- The Eligibility Checklist, Requirement by Requirement
- The 40-Hour Course vs. the 480 Practice Hours
- Preceptor Approval and Employer Recommendation
- Application Mechanics and Fees
- Exam Format Once You Qualify
- What the Exam Expects You to Know
- Matching Your Prep to the Requirements Timeline
- Keeping the Credential: Renewal Requirements
- Frequently Asked Questions
- You need an unrestricted RN license plus two years of hospital or clinic experience, or one year of critical care.
- Eligibility requires an approved 40-hour introductory course, then 480 post-course direct patient care hours with preceptor approval.
- The June 2026 application fee is US$250 for BNA members, US$300 for UHMS or ACHM members, US$400 for nonmembers.
- The exam has 120 multiple-choice and true/false items, a two-hour limit, and a 70% passing threshold.
Who Governs and Who Tests: BNACB and NBDHMT
Before you map out your path, it helps to know which organizations hold which responsibilities. The Certified Hyperbaric Registered Nurse credential involves two bodies, and candidates often confuse them. The Baromedical Nurses Association Certification Board (BNACB) oversees nursing eligibility and certification. The National Board of Diving and Hyperbaric Medical Technology (NBDHMT) administers and grades the examination at approved testing centers.
This split matters because your eligibility questions and your exam-day logistics go to different places in practice, even though the application packet brings them together. If you are still orienting yourself to the credential itself, our overview pages on what CHRN certification is and what CHRN stands for cover the basics. This article focuses on the practical question: do you qualify, and what exactly do you need to document?
The Eligibility Checklist, Requirement by Requirement
The published requirements stack in layers. You must satisfy every layer; there is no substitution of one for another except where a specific alternative is stated. Here is the full list as it appears across the current application and the June 2024 Resource Manual:
- An unrestricted registered nurse license. The word "unrestricted" is deliberate. A license under disciplinary restriction does not meet the standard.
- Clinical experience foundation. Two years of hospital or clinic experience, or one year of critical care experience.
- Recent active hyperbaric experience. A recent year of active involvement in hyperbaric practice.
- Approved introductory training. An approved 40-hour introductory course, or applicable 40 Category A replacement credits.
- 480 post-course patient-care hours. These hours must come after the course, not before.
- Qualified preceptor approval. Someone qualified must validate your hands-on competence.
- Employer recommendation. Your employer must support the application.
Why the experience pathway has two options
The clinical foundation can be met either through two years of general hospital or clinic experience or through a shorter one year of critical care. The shorter critical care route reflects how closely hyperbaric patient management resembles critical care nursing: continuous monitoring, vascular access lines, ventilated or unstable patients, and rapid recognition of deterioration. If you come from an ICU, ED, or similar high-acuity background, you may reach eligibility sooner than a nurse on a general floor.
"Recent active hyperbaric year" is not the same as the 480 hours
These are separate requirements and candidates regularly blur them. The recent active hyperbaric year speaks to currency: you have been working in the field lately. The 480 hours is a quantified block of direct patient care that must follow your introductory course. You will need documentation for both.
The 40-Hour Course vs. the 480 Practice Hours
Two numbers dominate the prerequisites, and neither is the exam timer. The 40-hour entry course and the 480 experience hours are prerequisites to sit for the exam, not part of the two-hour test itself. Mixing these up is a common source of confusion in online forums.
| Requirement | What It Is | Sequencing |
|---|---|---|
| 40-hour introductory course | Approved training (or applicable 40 Category A replacement credits) | Completed first |
| 480 patient-care hours | Direct patient care in hyperbaric practice | Accrued after the course |
| Preceptor approval | Validation of your competence by a qualified preceptor | Tied to the 480 hours |
| Employer recommendation | Employer support for your candidacy | Submitted with application |
Because the 480 hours must be post-course, the timing of your course matters. Nurses who take the introductory course early and begin logging supervised hours right away shorten their path. Those who take the course long after starting hyperbaric work may find that earlier hours do not count toward the 480. Confirm how your specific hours will be credited before assuming a timeline. For more on the educational component, see our page on CHRN training.
Preceptor Approval and Employer Recommendation
Two items on the checklist cannot be completed by you alone, so start them early.
Preceptor approval
A qualified preceptor must approve your hands-on practice. This is your evidence that the 480 hours were real, supervised, direct patient care and that you demonstrated competence, not merely time on the unit. Identify your preceptor at the start of your 480-hour period rather than at the end. A preceptor who has observed your work throughout can validate it far more credibly than one asked to sign off retroactively.
Employer recommendation
The employer recommendation ties your candidacy to your workplace. For nurses in hospital-based wound care and hyperbaric programs, this is usually a straightforward request. Nurses who float, work agency, or split time across facilities should clarify early who can speak to their hyperbaric work specifically.
Documentation Folder to Build as You Go
Gather these before you open the application:
- Copy of your active, unrestricted RN license
- Proof of qualifying clinical experience (two years hospital/clinic, or one year critical care)
- Certificate or credit record for the 40-hour introductory course or Category A replacement credits
- A running log of post-course patient-care hours toward the 480
- Preceptor approval
- Employer recommendation
- Membership evidence, if claiming a member fee
Application Mechanics and Fees
The current-linked June 2026 initial application confirms the fee schedule and the registration timing. Fees depend on your membership status, and the application requires membership evidence if you claim a discounted rate.
| Applicant Category | Initial Application Fee |
|---|---|
| BNA member | US$250 |
| UHMS or ACHM member | US$300 |
| Nonmember | US$400 |
The application instructs you to register 30 days before the test, so treat that as a hard planning constraint when you choose a testing date. For the current windows, see CHRN exam dates and scheduling.
On retakes: the June 2024 manual lists US$100 for a repeat examination. The retrieved initial application does not state a newer retake-fee override, so confirm the current repeat fee with NBDHMT before you budget for it. A full picture of what the credential costs across application, retake, and renewal is in our CHRN certification cost breakdown.
Exam Format Once You Qualify
Meeting the requirements gets you to the test. Here is what you will face, based on the June 2024 Resource Manual:
- 120 questions, multiple-choice and true/false only
- Two-hour time limit
- 70% passing threshold
- No essay or short-answer questions
- Supplemental dive tables are provided
- A pocket calculator is allowed
- Testing occurs at a designated testing site; any in-house proctorship requires NBDHMT approval
This is not default unproctored home testing. The exam is administered by NBDHMT at approved centers. The scored versus unscored item split, whether the test is adaptive, and the credential-specific pass rate have not been established in the public materials reviewed, so be wary of any source that states them with confidence. For the scoring standard itself, see CHRN passing score, and for what is and is not known about results, CHRN pass rate.
Because dive tables are supplied and a calculator is permitted, the exam expects applied reasoning, not memorization of table values. You should be fluent in using the tables, not in reciting them.
What the Exam Expects You to Know
Eligibility is only the first gate. The Resource Manual's study guide lists sixteen preparation topics, which are unweighted issuer study-guide competencies. The official weighted blueprint and the largest weighted domain have not been verified, so this article does not claim to know the percentage emphasis of any topic. The sixteen areas are:
- History of Undersea and Hyperbaric Medicine
- The Physical Aspects of Undersea and Hyperbaric Medicine
- The Physiological Aspects of Undersea and Hyperbaric Medicine
- Mechanisms and Theory of Decompression
- Therapeutic Mechanisms Associated with Hyperbaric Oxygen Exposure
- Currently Accepted Indications for Hyperbaric Oxygen Exposure
- Oxygen Toxicity
- Other Potential Complications
- The Hyperbaric Medicine Facility
- Hyperbaric Safety I: Protecting the Environment
- Hyperbaric Safety II: Protecting the Patient
- Understanding of the NFPA guidelines for hyperbaric chambers
- Transcutaneous Oxygen Monitoring
- Nursing Management of the Patient Undergoing Hyperbaric Oxygen Therapy
- Nursing Standards of Practice (BNA Hyperbaric Nursing Standards)
- Understanding of basic operation of all hyperbaric chambers, including monoplace and multiplace chambers
The full domain-by-domain treatment is in our complete guide to all 16 content areas. Here, the point is how your prerequisites connect to that scope.
Where Your 480 Hours Help Most
Hands-on hyperbaric work naturally reinforces several areas:
- Hyperbaric Safety II (Protecting the Patient): pre-treatment assessment, restricted-item removal, pressure equalization teaching, and gas-filled spaces in lines and monitoring equipment
- Nursing Management: care planning, medication interactions in the hyperoxic environment, and wound-healing adjuncts
- The Hyperbaric Medicine Facility and chamber operation: advantages and limitations of each chamber type
- Transcutaneous Oxygen Monitoring: TcPO2 equipment inspection, consent, and testing consistent with industry standards
Where Practice Alone Will Not Be Enough
Some areas rarely arise at the bedside but still appear in the published scope:
- The Physical Aspects: converting among ATA, FSW, PSI, MSW, and mmHg; applying Dalton's, Henry's, Boyle's, and Charles' Laws; converting among Fahrenheit, Celsius, Rankine, and Kelvin
- Mechanisms and Theory of Decompression: the U.S. Navy Standard Air Decompression Table, the No-Decompression Limits and Repetitive Group Designation Table, and the Residual Nitrogen Timetable
- History: the contributions of Behnke, Bert, Boerma, Bond, Boyle, Brummelkamp, Fontaine, Haldane, Henshaw, and Yarborough
- Currently Accepted Indications: the full UHMS list with commonly used pressure, exposure time, and frequency
One caution on sources: the manual contains legacy clinical narrative, including a reference to a 1992 indications report as the most recent. That statement is outdated. The public UHMS 15th-edition front matter is dated 2023 and lists later indications and updated references. Use the manual to establish scope, then verify clinical answers, accepted indications, and safety and nursing standards against current authoritative sources. Our CHRN study guide shows how to build that verification into your routine.
Matching Your Prep to the Requirements Timeline
The prerequisite structure gives you a natural study sequence, which is the one place generic scheduling advice earns its keep here. Use your eligibility milestones to decide what to study when:
Build the physical science foundation
- Pressure terminology and unit conversions
- Gas laws applied to hyperbaric scenarios
- Temperature conversions
Pair bedside work with safety and patient assessment
- Pre-exposure assessment and restricted items
- Barotrauma recognition and equalization teaching
- Oxygen toxicity presentations, central nervous system and pulmonary
Cover what bedside work skips
- Decompression tables and repetitive-dive logic
- History figures and contributions
- NFPA fire-safety guidance and compressed gas color codes
Verify and simulate
- Confirm accepted indications and protocols against current UHMS sources
- Timed practice sets mirroring 120 items in two hours
If you want to test your readiness while you are still logging hours, the CHRN practice test site lets you drill by topic, and you can find a quick last-pass review in our CHRN cheat sheet. To gauge the effort ahead, see how hard the CHRN exam is.
Key Takeaway
Do not wait until you qualify to start studying. The 480 post-course hours are your best study window, because supervised practice reinforces safety, patient assessment, and nursing management while you can still schedule dedicated time for the physics and decompression topics that practice does not cover.
Keeping the Credential: Renewal Requirements
Qualifying is one milestone; maintaining the credential is another. Renewal runs on a four-year cycle, and the August 2025 renewal form lays out these requirements:
- An active RN license
- Employer or medical director confirmation of at least one year of hyperbaric experience, including 480 hours within the last 12 months
- 40 continuing education hours over the four years, including 20 Category A hours
| Applicant Category | Renewal Fee (August 2025 form) |
|---|---|
| BNA member | US$150 |
| UHMS or ACHM member | US$200 |
| Nonmember | US$250 |
A lapse adds US$100 and removes member discounts. Note that the older manual's statement that ongoing hours need not be logged does not waive the newer form's employer-validated recent-practice requirement, so follow the newer form. Start tracking CE hours from day one and keep Category A hours distinct from the rest, since 20 of your 40 must be Category A.
For the career side of the equation, including who hires nurses with this credential, see CHRN jobs, our salary analysis, and the ROI discussion. If you are comparing paths, the central CHRN certification page ties these topics together.
Frequently Asked Questions
Yes. The requirements include a recent active hyperbaric year, an approved 40-hour introductory course (or applicable 40 Category A replacement credits), and 480 post-course patient-care hours validated by a preceptor, plus an employer recommendation.
Yes. The clinical foundation is met by either two years of hospital or clinic experience or one year of critical care experience. You still need the hyperbaric-specific requirements on top of that foundation.
The June 2026 initial application lists US$250 for BNA members, US$300 for UHMS or ACHM members, and US$400 for nonmembers, with membership evidence required. Register 30 days before your test. Retake and renewal fees are covered above.
No, not by default. Testing takes place at a designated testing site, and any in-house proctorship requires NBDHMT approval. The exam is 120 multiple-choice and true/false items in two hours, with a 70% passing threshold.
Renewal is every four years. You need an active RN license, employer or medical director confirmation of recent hyperbaric practice including 480 hours in the previous 12 months, and 40 CE hours with 20 in Category A. A lapse adds US$100 and removes member discounts.