CHRN Training

What "CHRN Training" Actually Covers

When nurses search for CHRN training, they usually mean one of three things: the required 40-hour introductory hyperbaric course, the supervised clinical experience that follows it, or the self-directed preparation for the certification exam. All three matter, and they happen in sequence. This guide separates them so you know what each stage demands.

The credential discussed here is the Certified Hyperbaric Registered Nurse certification. The Baromedical Nurses Association Certification Board (BNACB) oversees nursing eligibility and certification, while the National Board of Diving and Hyperbaric Medicine Technology (NBDHMT) administers and grades the examination. If you are still orienting yourself, the overview articles What Is CHRN Certification? and What Does CHRN Stand For? cover the basics before you commit to a training plan.

The Training Pathway: From Entry Course to Exam Day

The route from licensed RN to certified hyperbaric nurse runs through a defined series of steps. Each one must be documented before you can sit for the exam.

1. Hold an unrestricted RN license. This is the baseline for everything that follows.
2. Accumulate qualifying nursing experience. Two years of hospital or clinic experience, or one year of critical care.
3. Complete an approved 40-hour introductory course. Applicable Category A credits (40 replacement credits) can stand in for the course.
4. Log 480 post-course patient-care hours. These must be validated by a qualified preceptor.
5. Secure an employer recommendation. Your employer confirms your role and recent hyperbaric practice.
6. Register and test. The June 2026 application advises registering 30 days before the test.

For the full eligibility checklist and documentation expectations, see CHRN Requirements 2026: Eligibility, Prerequisites & How to Qualify. Scheduling windows and deadlines are covered in CHRN Exam Dates 2026.

Eligibility Gates You Must Clear First

The eligibility structure is where many candidates lose time. The requirements are cumulative, and several depend on timing.

The practical lesson: begin tracking your hours and preceptor sign-offs from your first day in the chamber. Reconstructing 480 hours of documentation months later is far harder than logging them as you go.

The Content Map: Sixteen Preparation Categories

The June 2024 CHRN Resource Manual is the anchor document for exam preparation. Its study-guide contents list sixteen technical preparation topics. These are issuer study-guide competencies, and they are unweighted. The manual's introduction refers to twelve sections while its detailed body contains thirteen, so neither figure should be treated as an authenticated count of official exam domains. Likewise, a complete current weighted blueprint has not been verified, so avoid any study resource that claims to tell you exactly how many questions come from each area.

The sixteen categories, in the order this site uses them:

1. History of Undersea and Hyperbaric Medicine
2. The Physical Aspects of Undersea and Hyperbaric Medicine
3. The Physiological Aspects of Undersea and Hyperbaric Medicine
4. Mechanisms and Theory of Decompression
5. Therapeutic Mechanisms Associated with Hyperbaric Oxygen Exposure
6. Currently Accepted Indications for Hyperbaric Oxygen Exposure
7. Oxygen Toxicity
8. Other Potential Complications
9. The Hyperbaric Medicine Facility
10. Hyperbaric Safety I: Protecting the Environment
11. Hyperbaric Safety II: Protecting the Patient
12. Understanding of the NFPA guidelines for hyperbaric chambers
13. Transcutaneous Oxygen Monitoring
14. Nursing Management of the Patient Undergoing Hyperbaric Oxygen Therapy
15. Nursing Standards of Practice (BNA Hyperbaric Nursing Standards)
16. Understanding of basic operation of all hyperbaric chambers, including monoplace and multiplace chambers

A deeper domain-by-domain walkthrough lives in CHRN Exam Domains 2026: Complete Guide to All 16 Content Areas. Here, the focus is on how to train for each cluster.

Physics, Physiology and Decompression: The Calculation Core

The first four content areas form the quantitative foundation. If your nursing background is strong clinically but light on gas laws, this is where deliberate training pays off.

Because supplemental dive tables are provided, your preparation should emphasize reading them fluently and under time pressure instead of memorizing their values. Practice finding the right table, entering it correctly, and interpreting the result.

Therapeutic Mechanisms, Indications and Oxygen Toxicity

This cluster connects physics to bedside decision-making. It is also where outdated study material can hurt you.

Therapeutic mechanisms

The objective names six mechanisms produced by oxygen partial pressures above one atmosphere absolute: antimicrobial effects, vasoconstriction, hyperoxygenation, neovascularization, attenuation of reperfusion injury, and gas bubble reduction. The higher-order skill is classification: you should be able to sort each currently accepted indication by its proposed therapeutic mechanism.

Currently accepted indications

You are expected to list the indications the Undersea and Hyperbaric Medical Society considers appropriate for hyperbaric referral, and to know the commonly used treatment protocols in terms of absolute pressure, exposure time and frequency. Build a table for yourself that pairs each indication with its mechanism and protocol parameters, then check it against the current UHMS reference.

Oxygen toxicity and other complications

• Central nervous system toxicity (Paul Bert effect) versus pulmonary toxicity (Lorrain Smith effect): know the clinical presentation of each and how to tell them apart.
• Extending tolerance: commonly used methods to extend patient tolerance to hyperbaric exposure.
• Prevention and management: principles for both central and pulmonary toxicity.
• Barotrauma risk: recognize anatomic and equipment gas-filled spaces before compression, educate patients, vent equipment, and recognize airway compromise during decompression.
• Complicating factors: the role of CNS oxygen toxicity and reactive airway disease during decompression.

These topics reward scenario thinking. Rehearse "what do I see, what do I do first" for each complication rather than only memorizing definitions. Our CHRN Cheat Sheet 2026 condenses many of these must-know contrasts onto a single review page.

Safety, Facility and Chamber Operations

Safety content is highly practical, and nurses who work daily in a chamber often have an advantage here. Still, the exam expects textbook-level precision.

Facility, NFPA and chamber operation

The facility domain asks for fundamental knowledge of each chamber type, with its advantages, disadvantages and operating characteristics. The sixteen-topic list also explicitly includes NFPA hyperbaric-chamber guidance and the operation of monoplace and multiplace chambers. One caution: the manual does not give separate detailed chapter bodies for NFPA, BNA standards, or chamber operation, and their full current external standards are not reproduced in the manual. Plan to consult the relevant external documents directly rather than assuming the manual covers them.

Nursing Management, Standards and TcPO2

These areas are the nursing heart of the certification. They test whether you can apply hyperbaric knowledge as a nurse, not only as a technician.

Nursing management of the HBO2 patient

• Human responses to actual or potential problems related to altered health status (physiological, psychological, sociological and cognitive)
• Applying the nursing process to develop a patient care plan
• Pharmacology, including drug interactions and altered drug effects in the hyperbaric hyperoxic environment
• Wound healing and adjunctive therapies that stimulate or enhance healing
• Care of critically ill and pediatric patients

Transcutaneous oxygen monitoring

TcPO2 competencies include working knowledge of the technology, the monitor and ancillary equipment, testing consistent with current industry standards, obtaining the subject's consent, and inspecting equipment before a study. Because this is a procedural topic, practice walking through a full study from consent to equipment inspection to interpretation.

BNA nursing standards of practice

The Baromedical Nurses Association publishes hyperbaric nursing standards on its website, and the preparation list directs candidates to them. Read them as a primary source and relate each standard to your own unit's workflow.

Exam Format, Registration and Fees

Knowing the mechanics prevents avoidable surprises. The June 2024 manual and the June 2026 application establish the following.

Several details remain unverified and should not be assumed: the split between scored and unscored items, whether the exam is adaptive, and a credential-specific pass rate. The historical 74% figure circulating in some places refers to a combined program, not CHRN specifically. For a careful look at what is and is not known, see CHRN Pass Rate 2026: What the Data Shows and CHRN Passing Score 2026. For a full fee picture across application, retake and renewal, see CHRN Certification Cost 2026: Complete Pricing Breakdown.

Sequencing Your Preparation Around the Content

Since the sixteen topics are unweighted, a sensible plan front-loads the areas that other topics depend on. Calculation fluency and gas laws make later physiology, decompression and safety content far easier to absorb. Here is one way to order the work after you have logged your clinical hours.

Pacing matters: 120 items in two hours leaves roughly one minute per question, so timed practice is part of the training, not an afterthought. For a broader strategy that fits this structure, read CHRN Study Guide 2026: How to Pass on Your First Attempt, and if you are weighing your readiness, How Hard Is the CHRN Exam? offers perspective.

When you are ready to test your recall under realistic conditions, the CHRN practice tests on the main site let you drill each content area and simulate the timing of the real exam.

After Certification: Renewal and Practice Requirements

Training does not end at certification. The credential renews every four years, and the requirements reflect ongoing hyperbaric practice.

• Active RN license maintained throughout
• 40 continuing education hours over the four-year cycle, including 20 Category A hours
• Recent-practice validation: employer or medical director confirmation of at least one year of hyperbaric experience, including 480 hours within the previous 12 months

The August 2025 renewal form lists fees of US$150 for BNA members, US$200 for UHMS or ACHM members, and US$250 for nonmembers. A lapse adds US$100 and removes member discounts. Note that an older manual statement suggesting ongoing hours need not be logged does not waive the newer form's employer-validated recent-practice requirement. Always follow the current form.

If you are weighing the career side of the investment, see CHRN Jobs for where certified hyperbaric nurses practice, CHRN Salary Guide 2026 for earnings context, and Is the CHRN Certification Worth It? for a fuller ROI discussion.

Frequently Asked Questions

For a plain-language starting point on the credential itself, revisit CHRN Certification or What Is A CHRN?, then build your training plan around the content map above.