- ACHRN is an advancement credential from CHRN, not a separate exam - issued by the Baromedical Nurses Association Certification Board (BNACB) through NBDHMT.
- Applicants need three-plus years as a CHRN, a valid RN license, and 480 hyperbaric hours in the preceding 12 months.
- You must submit 60 continuing education hours from the prior four years, with at least 30 Category A hours in hyperbaric oxygen therapy.
- Advancement fees run $150 (BNA members), $200 (UHMS/ACHM members), or $250 (nonmembers), with renewal every four years.
What Is an ACHRN?
ACHRN stands for Advanced Certified Hyperbaric Registered Nurse. It is the advanced-tier credential administered by the Baromedical Nurses Association Certification Board (BNACB) through the National Board of Diving and Hyperbaric Medical Technology (NBDHMT). Unlike most nursing specialty credentials, ACHRN is not earned through a standalone written examination. Instead, it is an advancement awarded to registered nurses who already hold current CHRN (Certified Hyperbaric Registered Nurse) certification and who can document additional clinical hours, continuing education, and professional contributions to the hyperbaric field.
If you searched "what is a ACHRN" hoping to find exam dates, domain breakdowns, or a scoring rubric specific to an ACHRN test, that content doesn't exist - because there is no separate ACHRN exam. This distinction matters enough that we cover it in detail on our page explaining what ACHRN means and in our broader breakdown of ACHRN's meaning within hyperbaric nursing.
CHRN vs. ACHRN: What Actually Changes
CHRN certification confirms baseline competency in hyperbaric nursing through a proctored exam. ACHRN builds on that foundation by verifying sustained, documented experience and professional contribution over time. Think of CHRN as proof you can safely practice hyperbaric nursing today, and ACHRN as proof you've been doing it well, consistently, and at a level that includes teaching, administration, or care-coordination responsibility.
| Element | CHRN | ACHRN |
|---|---|---|
| Format | 120-question timed exam | Document review, no new exam |
| Prerequisite | RN license, hyperbaric training | Current CHRN status, 3+ years certified |
| Verification | Exam score (70% to pass) | Manager/medical-director sign-off |
| Renewal cycle | Periodic recertification | Every four years |
For a full breakdown of every eligibility line item on the advanced form, see our dedicated ACHRN requirements guide. If you're still building your CHRN foundation, our ACHRN study guide walks through the prerequisite exam preparation timeline in detail.
Advancement Requirements Explained
The June 2024 CHRN resource manual update opened the advanced application to nurses who have held CHRN certification for at least three years. The August 2025 advancement/recertification form spells out exactly what must be submitted alongside that eligibility window:
Core Eligibility Checklist
Before you file an advancement application, confirm you can document all of the following:
- Current, unexpired CHRN certification
- A valid, unrestricted RN license
- At least three years of documented hyperbaric nursing experience
- At least 480 hyperbaric hours in the preceding 12 months, verified by a hyperbaric unit manager or medical director
- 60 continuing education hours from the preceding four years
- At least 30 of those CE hours classified as Category A hyperbaric oxygen therapy content
The 480-hour requirement is worth flagging separately because it's the piece candidates most often underestimate. It isn't a lifetime total - it's hours worked in the 12 months immediately preceding your application, signed off by someone in a supervisory or medical-director role at your facility. Nurses who rotate between hyperbaric and other units should track this hour count deliberately rather than assuming it will simply add up.
Key Takeaway
Start logging your hyperbaric hours and Category A continuing education credits well before your three-year CHRN anniversary - retroactive documentation is far harder to assemble than a running log.
The Four Contribution Categories
Beyond hours and continuing education, the advancement form asks applicants to document at least two of four professional contribution categories. This is the part of the ACHRN pathway that most clearly separates it from a typical recertification and rewards nurses who've taken on leadership or educational roles within hyperbaric medicine.
1. Hyperbaric Unit Administration
Responsibility for departmental operations, scheduling, policy development, or supervisory oversight within a hyperbaric program.
2. Teaching or Presenting Hyperbaric Lectures
Delivering formal instruction or presentations on hyperbaric oxygen therapy topics to staff, students, or professional audiences.
3. Nursing-Care Planning or Coordination
Holding primary responsibility for designing or coordinating the nursing care plan for hyperbaric patients, not simply delivering treatments.
4. BNA or UHMS Officer/Committee Participation
Serving in an elected, appointed, or committee role within the Baromedical Nurses Association or the Undersea and Hyperbaric Medical Society.
Applicants only need two of the four, but the documentation for each must be specific - dates, roles, and verifying signatures rather than a general description of job duties. Our ACHRN certification overview goes further into how these categories are typically evidenced on the application.
Fees and Renewal Cycle
Advancement and recertification fees vary by professional membership status rather than by application complexity:
| Applicant Category | Fee |
|---|---|
| BNA members | $150 USD |
| UHMS or ACHM members | $200 USD |
| Nonmembers | $250 USD |
Once granted, ACHRN status renews on a four-year cycle. Renewal isn't automatic - nurses must continue to satisfy the advanced requirements, keep an active RN license, and resubmit supporting documentation each cycle. For a complete line-item cost picture, including how membership status affects total spend over multiple renewal cycles, read our ACHRN certification cost breakdown.
The CHRN Exam You Must Pass First
Since ACHRN has no exam of its own, the only scored test standing between you and eventual advancement is the CHRN exam. Understanding its format matters even for nurses already years into hyperbaric practice, because CHRN status must remain current and valid throughout the advancement process.
If you're new to hyperbaric nursing or your CHRN certification has lapsed, you'll need to pass this exam before the three-year advancement clock can even start. Our team maintains clearly labeled one-page review material summarizing must-know facts, along with a full content-area guide and analysis of exam difficulty for nurses evaluating how much preparation time to budget. You can also review realistic passing score expectations and check current testing windows and deadlines before you register.
Who Hires ACHRNs
ACHRN-advanced nurses typically work in the same clinical settings as CHRNs - wound care and hyperbaric centers, hospital-based hyperbaric departments, and outpatient HBOT clinics - but the advancement itself signals something specific to employers: sustained hands-on experience combined with leadership, teaching, or care-coordination responsibility. Facilities building or expanding a hyperbaric program often look for ACHRN-advanced nurses specifically when filling charge-nurse, program-coordinator, or clinical-educator roles, since the credential's contribution categories map directly onto those responsibilities.
If you're weighing whether pursuing the advancement is worth the documentation effort, our ROI analysis looks at how the credential factors into career trajectory, and our earnings guide discusses how advanced hyperbaric credentials are typically valued in practice.
How to Prepare for the Pathway
Preparation for ACHRN advancement looks different from studying for a timed exam - it's a documentation and planning exercise spread across your three years as a CHRN. That said, if you still need to pass the CHRN prerequisite exam, a focused study block is warranted before you turn attention to hour-logging and CE tracking.
Establish Your CHRN Foundation
- Pass or confirm current CHRN status
- Begin logging hyperbaric hours from day one
Accumulate Qualifying Experience
- Track Category A CE hours toward the 30-hour minimum
- Document leadership, teaching, or care-coordination activity as it happens
Assemble the Advancement Application
- Confirm 480 recent hyperbaric hours with supervisor sign-off
- Select two contribution categories with strongest documentation
For nurses still working through the CHRN prerequisite, practicing with realistic question formats matters more than memorization drills. You can run through timed, exam-style questions on our practice test platform to get comfortable with the 120-question, two-hour format before test day, and revisit our ACHRN training resources for structured review between practice sessions.
Key Takeaway
Treat the CHRN exam and the ACHRN advancement as two separate projects on two separate timelines - one is a study sprint, the other is a multi-year documentation habit.
Frequently Asked Questions
No. ACHRN is an advancement from CHRN based on documented experience, continuing education, and professional contributions - not a standalone examination. The only scored, timed exam in this pathway is the CHRN prerequisite exam.
The June 2024 resource manual permits an advanced application after three years of CHRN certification, provided you also meet the hours, continuing education, and contribution documentation requirements.
At least 480 hyperbaric hours in the 12 months preceding your application, verified by a hyperbaric unit manager or medical director, plus at least three years of overall hyperbaric experience.
Sixty continuing education hours from the preceding four years, including a minimum of 30 Category A hours specifically in hyperbaric oxygen therapy.
Fees are $150 USD for BNA members, $200 USD for UHMS or ACHM members, and $250 USD for nonmembers, based on the current advancement/recertification form.