Certified Hyperbaric Specialist (CHS) Exam — Questions and Answers

Question 1: What is peer review in CHS Patient Assessment & Evaluation?

Quality evaluation by qualified colleagues for improvement (Correct answer)
Creating competition
Determining promotions
Reducing workloads

Correct answer: Quality evaluation by qualified colleagues for improvement

Peer review provides objective assessment by qualified professionals to identify improvements and ensure accountability.

Question 2: What is a milestone in CHS project management?

A physical construction marker
An optional checkpoint
A significant event marking progress at a key point in the timeline (Correct answer)
A daily required task

Correct answer: A significant event marking progress at a key point in the timeline

Milestones are significant checkpoints marking completion of major deliverables or phase transitions.

Question 3: A hyperbaric chamber's depth gauge reads 66 FSW (feet of seawater). What is the equivalent pressure in ATA?

4 ATA
3 ATA (Correct answer)
2.5 ATA
2 ATA

Correct answer: 3 ATA

Each 33 FSW equals 1 additional atmosphere, so 66 FSW equals 2 additional atmospheres plus 1 ATA surface pressure = 3 ATA total.

Question 4: How does professional liability insurance protect CHS practitioners?

Covering disaster damage
Paying health premiums
Protecting against equipment theft
Covering financial losses from claims of negligence or errors (Correct answer)

Correct answer: Covering financial losses from claims of negligence or errors

This insurance covers financial consequences of claims alleging negligence or mistakes in professional services.

Question 5: What does 'MAWP' stand for in the context of hyperbaric pressure vessels?

Mean Adjusted Working Parameter
Maximum Atmospheric Working Protocol
Maximum Allowable Working Pressure (Correct answer)
Minimum Ambient Water Pressure

Correct answer: Maximum Allowable Working Pressure

MAWP (Maximum Allowable Working Pressure) is the highest pressure at which a pressure vessel is designed and certified to operate safely.

Question 6: When a diver with suspected AGE presents for HBOT, what is the recommended immediate positioning during transport?

Sitting upright at 90 degrees
Supine with head at the same level as the body (Correct answer)
Steep Trendelenburg (head down) position
Left lateral decubitus (Durant's maneuver) for all cases

Correct answer: Supine with head at the same level as the body

Current guidelines recommend supine positioning; head-down positioning is no longer recommended as it may increase cerebral edema without proven benefit in reducing bubble migration.

Question 7: What information is typically gathered during a patient assessment?

Family background
Name and address
Medical history, conditions, contraindications, and medications (Correct answer)
Dietary habits

Correct answer: Medical history, conditions, contraindications, and medications

A comprehensive patient assessment for hyperbaric therapy involves gathering detailed information about their medical history, including past surgeries and chronic conditions. It also identifies any specific contraindications that would make the treatment unsafe, such as an untreated pneumothorax. Furthermore, a complete list of current medications is essential to check for potential interactions or adverse effects under hyperbaric conditions.

Question 8: Pulmonary (Lorrain Smith) oxygen toxicity is associated with prolonged exposure to a PO2 greater than:

2.0 ATA
0.21 ATA
0.5 ATA (Correct answer)
1.0 ATA

Correct answer: 0.5 ATA

Pulmonary oxygen toxicity occurs with prolonged exposure to PO2 greater than 0.5 ATA, causing tracheobronchitis and alveolar damage over time.

Question 9: What differentiates active from inactive records in CHS?

Active are regularly referenced; inactive are retained but rarely accessed (Correct answer)
Active are digital; inactive are paper
Inactive have no value
Active are public; inactive are private

Correct answer: Active are regularly referenced; inactive are retained but rarely accessed

Active records are frequently referenced; inactive ones are retained for legal or historical purposes but rarely needed.

Question 10: The term 'squeeze' in hyperbaric medicine refers to barotrauma affecting:

Gas-filled body spaces that cannot equalize pressure during compression (Correct answer)
Excessive cardiac output at depth
Nitrogen bubble formation in joints
Vascular compression during rapid ascent

Correct answer: Gas-filled body spaces that cannot equalize pressure during compression

Squeeze describes barotrauma in gas-filled cavities (ears, sinuses, teeth, lungs) when descent/compression occurs faster than the cavity can equalize pressure.

Question 11: What is oxygen toxicity?

A form of allergic reaction
A temporary side effect
A beneficial effect of hyperbaric therapy
A condition caused by prolonged high oxygen exposure (Correct answer)

Correct answer: A condition caused by prolonged high oxygen exposure

Oxygen toxicity is an adverse reaction that occurs when the body is exposed to high partial pressures of oxygen for extended periods, as can happen in hyperbaric therapy. This exposure leads to the generation of harmful reactive oxygen species, which can damage cells and tissues, particularly in the central nervous system and lungs. Careful management of oxygen concentration and exposure time is essential to prevent it.

Question 12: During emergency decompression of a multi-place chamber with an unconscious patient inside, the inside attendant should:

Maintain airway, prevent breath-holding, and prepare for immediate post-decompression evaluation (Correct answer)
Secure all loose equipment and exit the chamber first for their own safety
Perform CPR continuously regardless of the patient's respiratory status
Administer 100% oxygen via tight-fitting mask while monitoring ascent rate

Correct answer: Maintain airway, prevent breath-holding, and prepare for immediate post-decompression evaluation

During emergency decompression, airway management and preventing breath-holding are critical to avoid pulmonary barotrauma and arterial gas embolism.

Question 13: What is the primary reason that blood glucose control is critical in diabetic patients undergoing HBOT for wound healing?

High glucose enhances HBOT effectiveness
Hyperglycemia impairs leukocyte function and vasoregulation, undermining HBOT benefits (Correct answer)
Blood glucose has no effect on wound healing under pressure
Low glucose is dangerous only during chamber pressurization

Correct answer: Hyperglycemia impairs leukocyte function and vasoregulation, undermining HBOT benefits

Hyperglycemia directly impairs neutrophil chemotaxis and killing, compromises microvascular function, and reduces the wound healing gains from HBOT.

Question 14: When documenting the outcome of HBO treatments for a diabetic foot ulcer, which metric best quantifies wound healing progress?

Number of antibiotic courses completed during treatment
Weekly hemoglobin A1c values
Serial wound surface area measurements and depth recordings (Correct answer)
Patient-reported pain score on a numeric rating scale

Correct answer: Serial wound surface area measurements and depth recordings

Serial objective wound measurements — surface area and depth — provide the most direct evidence of healing progress and guide decisions to continue or modify therapy.

Question 15: What is evidence-based practice in CHS Patient Assessment & Evaluation?

Following intuition only
Doing whatever clients request
Using newest unproven methods
Integrating research evidence with expertise and client needs (Correct answer)

Correct answer: Integrating research evidence with expertise and client needs

Evidence-based practice combines research, expertise, and client preferences for optimal outcomes.

Question 16: What is the maximum delay between DCS symptom onset and first HBOT treatment still considered likely to provide neurological benefit?

2 hours
6 hours only
There is no absolute cutoff; treat as soon as possible even if delayed by hours or days (Correct answer)
30 minutes

Correct answer: There is no absolute cutoff; treat as soon as possible even if delayed by hours or days

While earlier treatment is always better, HBOT can still provide benefit in DCS even when delayed by 24 hours or more, particularly for neurological symptoms, and should never be withheld solely due to delay.

Question 17: A patient receiving HBO for sudden sensorineural hearing loss (SSHL) asks how many sessions are typically required. According to evidence-based protocols, what is the usual treatment course?

20–40 sessions at 2.0–2.5 ATA, typically initiated within 2 weeks of onset (Correct answer)
10 sessions at 1.5 ATA sufficient for most patients
5 sessions at 3.0 ATA for acute cases only
60 sessions at 2.4 ATA regardless of response

Correct answer: 20–40 sessions at 2.0–2.5 ATA, typically initiated within 2 weeks of onset

For SSHL, guidelines generally recommend 20–40 sessions at 2.0–2.5 ATA initiated as early as possible, ideally within 2 weeks of symptom onset.

Question 18: Which personnel certification is specifically recognized for hyperbaric chamber operators in the United States?

Certified Respiratory Therapist (CRT)
Certified Biomedical Equipment Technician (CBET)
Certified Pulmonary Function Technologist (CPFT)
Certified Hyperbaric Technologist (CHT) through NBDHMT (Correct answer)

Correct answer: Certified Hyperbaric Technologist (CHT) through NBDHMT

The National Board of Diving and Hyperbaric Medical Technology (NBDHMT) issues the CHT credential, which is the recognized certification for hyperbaric technologists in the US.

Question 19: What is informed consent in CHS professional practice?

Providing complete information about services, risks, and alternatives for voluntary decisions (Correct answer)
Having clients sign without explanation
Verbal agreement only
Third-party consent

Correct answer: Providing complete information about services, risks, and alternatives for voluntary decisions

Informed consent requires clear, complete information about proposed services, risks, outcomes, and alternatives so clients can make knowledgeable decisions.

Question 20: A fire breaks out inside a Class A multi-place hyperbaric chamber during treatment. What is the FIRST priority action?

Increase chamber pressure to suppress combustion
Activate internal fire suppression system immediately
Initiate emergency decompression and notify the fire department (Correct answer)
Flood the chamber with 100% nitrogen

Correct answer: Initiate emergency decompression and notify the fire department

Life safety is the first priority; emergency decompression removes occupants while fire suppression and emergency services are simultaneously activated.

Question 21: A hyperbaric chamber operator discovers a patient is experiencing arterial gas embolism (AGE) immediately after surfacing from a dive. The treatment protocol of choice is:

US Navy Treatment Table 5 for air embolism
Recompression to 6 ATA on air alone
Oxygen at 2.0 ATA for 60 minutes only
US Navy Treatment Table 6 with oxygen breathing (Correct answer)

Correct answer: US Navy Treatment Table 6 with oxygen breathing

USN Table 6 at 2.8 ATA with oxygen periods is the standard recompression treatment for AGE and severe decompression sickness.

Question 22: Which treatment table is specifically indicated for decompression sickness Type I (pain-only) when symptoms are mild and resolved within 10 minutes of oxygen breathing?

US Navy Treatment Table 4
US Navy Treatment Table 5 (Correct answer)
US Navy Treatment Table 6
US Navy Treatment Table 9

Correct answer: US Navy Treatment Table 5

USN Table 5 is the shorter table designed for mild Type I DCS (musculoskeletal pain only) when symptoms respond quickly to oxygen at depth.

Question 23: Barodontalgia (tooth squeeze) during HBO therapy is most commonly caused by:

Gas trapped beneath dental restorations, in caries, or under crowns (Correct answer)
Increased pulpal blood flow from vasoconstriction
Fluoride release from sealants during compression
Calcium depletion from tooth enamel under pressure

Correct answer: Gas trapped beneath dental restorations, in caries, or under crowns

Gas pockets trapped within dental defects, restorations, or beneath poorly fitting crowns undergo compression and expansion during pressure changes, causing pain or structural injury.

Question 24: What is the primary purpose of a code of ethics in CHS practice?

To determine salary structures
To define standard office hours
To set pricing for professional services
To establish professional conduct standards and guide ethical decision-making (Correct answer)

Correct answer: To establish professional conduct standards and guide ethical decision-making

A code of ethics provides a framework of professional values and behavioral standards that guides practitioners in ethical decisions while maintaining public trust.

Question 25: A patient receiving HBO for a diabetic foot ulcer suddenly reports visual changes and facial twitching after 40 minutes at 2.4 ATA. What is the immediate priority?

Increase depth to 3.0 ATA to stop bubble formation
Administer IV diazepam and continue the treatment
Decompress immediately to 1.0 ATA and terminate the session
Remove the oxygen mask and switch to air breathing (Correct answer)

Correct answer: Remove the oxygen mask and switch to air breathing

These are prodromal signs of central nervous system oxygen toxicity; immediately switching to air breathing typically aborts the progression to seizure.

Question 26: In a hyperbaric facility, the purpose of a continuous oxygen monitoring system inside the chamber is to:

Ensure nitrogen levels remain below 5% during air breaks
Confirm that the patient is breathing 100% oxygen throughout treatment
Monitor patient SpO2 levels in real time
Detect oxygen enrichment above 23.5% and trigger alarms to prevent fire hazard (Correct answer)

Correct answer: Detect oxygen enrichment above 23.5% and trigger alarms to prevent fire hazard

Continuous O2 monitoring detects leaks from patient breathing circuits that could enrich chamber atmosphere to fire-hazard levels above 23.5%.

Question 27: Which wound characteristic most strongly supports the use of HBOT as an adjunct for a diabetic lower extremity ulcer?

Full-thickness wound with exposed tendon and wound culture growing MRSA
Wound with periwound TcPO2 below 40 mmHg that rises above 200 mmHg on HBO challenge (Correct answer)
Superficial wound less than 2 cm² with good granulation tissue
Wound present for more than 30 days with adequate perfusion and no infection

Correct answer: Wound with periwound TcPO2 below 40 mmHg that rises above 200 mmHg on HBO challenge

Periwound hypoxia on room air with a robust response to the HBO oxygen challenge is the strongest evidence-based indicator for HBOT benefit in diabetic wound healing.

Question 28: What clinical sign at a wound site would suggest an anaerobic infection that may specifically benefit from HBOT?

Crepitus (gas in tissues) with foul-smelling exudate (Correct answer)
Clear serous drainage
Bright red granulation tissue
Intact surrounding skin

Correct answer: Crepitus (gas in tissues) with foul-smelling exudate

Crepitus from gas-producing anaerobes combined with malodorous exudate strongly suggests a clostridial or mixed anaerobic infection — a direct indication for adjunctive HBOT.

Question 29: What pre-treatment measure should a CHS technologist perform for a diver presenting with AGE before the patient enters the chamber?

Give the patient water to drink to rehydrate nitrogen out of tissues
Administer high-flow 100% normobaric oxygen by tight-fitting mask during pre-chamber preparation (Correct answer)
Apply compression bandages to the extremities
Restrict oxygen use to prevent further embolism

Correct answer: Administer high-flow 100% normobaric oxygen by tight-fitting mask during pre-chamber preparation

Continuous 100% normobaric oxygen before and during transport accelerates nitrogen washout, reduces bubble size, and maintains cerebral oxygenation while preparing for HBOT.

Question 30: Inner ear DCS (vestibular DCS) presents with which classic triad of symptoms?

Joint pain, skin mottling, and fatigue
Chest pain, dyspnea, and coughing
Vertigo, tinnitus, and sensorineural hearing loss (Correct answer)
Confusion, visual disturbances, and hemiparesis

Correct answer: Vertigo, tinnitus, and sensorineural hearing loss

Vestibular DCS causes bubble formation in the highly vascular inner ear, producing the classic triad of vertigo, tinnitus, and hearing loss due to disrupted cochlear and vestibular perfusion.

Question 31: What is a CHS professional's obligation regarding confidentiality?

Using as marketing material
Discussing cases with family
Protecting client information and disclosing only with authorization or legal requirement (Correct answer)
Sharing freely with other professionals

Correct answer: Protecting client information and disclosing only with authorization or legal requirement

Confidentiality requires protecting all client information from unauthorized disclosure, sharing only with consent or legal mandate.

Question 32: When a hyperbaric facility is inspected for CMS certification, the surveyor will verify compliance with which life safety code?

OSHA 29 CFR 1910 General Industry Standards exclusively
ASME PVHO-1 and the International Building Code (IBC)
NFPA 101 Life Safety Code and NFPA 99 Health Care Facilities Code (Correct answer)
Only the state health department's facility licensing regulations

Correct answer: NFPA 101 Life Safety Code and NFPA 99 Health Care Facilities Code

CMS requires compliance with NFPA 101 and NFPA 99 as conditions of participation for healthcare facilities, including hyperbaric units.

Question 33: A diver reports progressive tingling in both legs after surfacing from a deep dive. This bilateral lower extremity paresthesia most likely indicates what type of DCS?

Inner ear DCS (vestibular)
Cutaneous DCS
Spinal cord DCS (Type II), requiring urgent HBOT (Correct answer)
Type I DCS (limb pain only)

Correct answer: Spinal cord DCS (Type II), requiring urgent HBOT

Bilateral paresthesias of the lower extremities strongly suggest spinal cord bubble formation affecting the thoracic or lumbar cord, classifying this as Type II (neurological) DCS.

Question 34: The Unit Pulmonary Toxicity Dose (UPTD) is used in HBO therapy to track:

Seizure risk from CNS oxygen toxicity
Cumulative pulmonary oxygen exposure to prevent pulmonary toxicity (Correct answer)
Cumulative carbon monoxide exposure in CO poisoning patients
Nitrogen narcosis risk during treatment

Correct answer: Cumulative pulmonary oxygen exposure to prevent pulmonary toxicity

UPTD is a mathematical unit that quantifies cumulative pulmonary oxygen exposure across multiple treatments, helping clinicians schedule safe HBO therapy and prevent pulmonary oxygen toxicity.

Question 35: A CHS technologist notes that a patient's transcutaneous oxygen measurement (TCOM) at the wound site is 8 mmHg on room air. What does this finding indicate?

Patient is ready for discharge from HBOT
Normal baseline value requiring no further assessment
Severely compromised tissue perfusion unlikely to heal without intervention (Correct answer)
Excellent wound healing potential

Correct answer: Severely compromised tissue perfusion unlikely to heal without intervention

A periwound TCOM below 20 mmHg indicates critical ischemia, and values below 30 mmHg are associated with poor spontaneous healing potential.

Question 36: A patient receiving HBO therapy for a diabetic foot wound has a blood glucose of 42 mg/dL before entering the chamber. The correct action is:

Reduce treatment pressure to 1.5 ATA to minimize metabolic demand
Proceed with treatment and administer glucose via the chamber medication port
Cancel the treatment session for the day only if the patient is symptomatic
Delay treatment, correct hypoglycemia, and recheck glucose before proceeding (Correct answer)

Correct answer: Delay treatment, correct hypoglycemia, and recheck glucose before proceeding

HBO accelerates glucose metabolism and can worsen hypoglycemia; treatment must be deferred until glucose is normalized and stable.

Question 37: What is a needs assessment in CHS Patient Assessment & Evaluation practice?

Benefits survey
Property appraisal
Office supply list
Identifying gaps between current conditions and desired outcomes (Correct answer)

Correct answer: Identifying gaps between current conditions and desired outcomes

A needs assessment identifies gaps between current performance and desired outcomes to justify improvements.

Question 38: How does high-pressure oxygen therapy affect the immune system?

Stimulates the immune system and promotes healing (Correct answer)
Inhibits infection
Reduces blood flow
Decreases immune response

Correct answer: Stimulates the immune system and promotes healing

High-pressure oxygen stimulates the immune system, helping to fight infections and promote healing.

Question 39: When a patient experiences middle ear barotrauma and is unable to equalize at 0.5 ATA overpressure, the appropriate action is:

Immediately abort treatment and surface at maximum rate
Switch the patient to air breathing to reduce oxygen toxicity risk
Continue pressurization and administer nasal decongestant via the chamber port
Halt compression, ascend slightly, and assist the patient with equalization techniques (Correct answer)

Correct answer: Halt compression, ascend slightly, and assist the patient with equalization techniques

Standard protocol is to pause or slightly reduce pressure to allow equalization attempts before continuing or aborting treatment.

Question 40: Which condition is treated with US Navy Treatment Table 5 rather than Table 6?

Arterial gas embolism
Carbon monoxide poisoning
Mild Type I DCS (pain only) that resolves completely with initial oxygen breathing at 60 fsw (Correct answer)
Type II DCS with neurological symptoms

Correct answer: Mild Type I DCS (pain only) that resolves completely with initial oxygen breathing at 60 fsw

USN TT5 is appropriate for mild Type I DCS (musculoskeletal pain, skin symptoms) that fully resolves during the initial oxygen-breathing period at 60 fsw, indicating a favorable response.

Question 41: Necrotizing fasciitis is a UHMS-approved indication for HBOT. What is the primary rationale for using HBOT as an adjunct in this condition?

HBOT seals the fascial planes to stop spread
Elevated tissue pO2 enhances leukocyte bactericidal activity against anaerobic organisms (Correct answer)
HBOT replaces surgical debridement as the primary treatment
HBOT reduces the need for antibiotic therapy

Correct answer: Elevated tissue pO2 enhances leukocyte bactericidal activity against anaerobic organisms

HBOT raises local tissue oxygen levels, restoring the oxidative killing capacity of neutrophils against anaerobic and mixed-flora bacteria involved in necrotizing fasciitis.

Question 42: What is the correct fluid resuscitation approach for a diver presenting with DCS?

Give only hypotonic fluids to dilute nitrogen concentration
Administer isotonic oral or intravenous fluids to maintain adequate hydration and promote nitrogen off-gassing (Correct answer)
Restrict all fluids to prevent cerebral edema
Fluid resuscitation is contraindicated in all DCS cases

Correct answer: Administer isotonic oral or intravenous fluids to maintain adequate hydration and promote nitrogen off-gassing

Adequate hydration with isotonic fluids supports tissue perfusion, reduces blood viscosity, and optimizes the gradient for nitrogen diffusion from tissues into circulation for pulmonary excretion.

Question 43: What is a common protocol for hyperbaric therapy treatment duration?

15 minutes
30 minutes
60 to 120 minutes (Correct answer)
4 hours

Correct answer: 60 to 120 minutes

The typical duration for a single hyperbaric oxygen therapy session generally ranges from 60 to 120 minutes. This timeframe is established to allow sufficient exposure to hyperbaric oxygen for therapeutic effects to occur, while also balancing the risk of oxygen toxicity and patient comfort. Specific durations can vary based on the treated condition and physician's protocol.

Question 44: According to UHMS accreditation standards, the hyperbaric physician director must hold:

Board certification in pulmonary medicine or critical care
Physician training in hyperbaric medicine approved by UHMS or an equivalent credentialing body (Correct answer)
A CHT credential in addition to their medical license
At minimum 500 hours of supervised multi-place chamber time

Correct answer: Physician training in hyperbaric medicine approved by UHMS or an equivalent credentialing body

UHMS accreditation requires the medical director to complete UHMS-approved hyperbaric medicine training; no specific specialty board is mandated.

Question 45: What is the term for the pressure at which nitrogen narcosis first becomes noticeable in most divers breathing air?

3.0 ATA (Correct answer)
2.0 ATA
1.5 ATA
4.0 ATA

Correct answer: 3.0 ATA

Nitrogen narcosis typically begins to impair cognitive function at approximately 3.0 ATA (equivalent to about 66 feet of seawater) when breathing compressed air.

Question 46: A patient with DCS is being treated with USN TT6 and reports symptom recurrence after initial improvement. What is the appropriate response?

Switch immediately to TT5
Ascend the chamber to surface pressure
End the treatment immediately
Extend the table by adding oxygen breathing periods or repeat TT6 as directed by the physician (Correct answer)

Correct answer: Extend the table by adding oxygen breathing periods or repeat TT6 as directed by the physician

Symptom recurrence or inadequate resolution during TT6 warrants table extension with additional 20-minute oxygen-breathing periods or repeat treatments under physician direction.

Question 47: What should a CHS professional do upon discovering a colleague's unethical conduct?

Confront publicly at a meeting
Report through appropriate channels with proper documentation (Correct answer)
Post anonymously online
Ignore it to maintain harmony

Correct answer: Report through appropriate channels with proper documentation

Professionals have an obligation to report misconduct through proper channels while documenting observations to support investigation.

Question 48: Which biofilm characteristic makes chronic wounds particularly resistant to standard antibiotic therapy?

Biofilms are only found in acute wounds
Biofilms increase tissue perfusion making bacteria more active
Biofilms release oxygen to sustain bacteria
Biofilm matrix protects bacteria from antibiotics and immune cells (Correct answer)

Correct answer: Biofilm matrix protects bacteria from antibiotics and immune cells

The extracellular polysaccharide matrix of biofilms creates a physical and chemical barrier that shields embedded bacteria from both antibiotic penetration and phagocytic attack.

Question 49: What is the significance of the 'unit pulmonary toxicity dose' (UPTD) in planning a patient's HBOT course?

It calculates the total dose of oxygen absorbed across all tissues during a session
It quantifies the total number of sessions a patient can safely receive in a lifetime
It provides a cumulative measure of pulmonary oxygen exposure to guide safe scheduling of treatments (Correct answer)
It determines the maximum depth achievable without pulmonary damage

Correct answer: It provides a cumulative measure of pulmonary oxygen exposure to guide safe scheduling of treatments

UPTD is a cumulative index of pulmonary oxygen exposure that helps clinicians monitor and limit pulmonary toxicity risk over a treatment course.

Question 50: The ASME PVHO-1 standard governs the design and construction of pressure vessels intended for:

Human occupancy under pressure (Correct answer)
Medical oxygen cylinders
Industrial gas storage only
Submarine hull construction

Correct answer: Human occupancy under pressure

ASME PVHO-1 specifically applies to pressure vessels for human occupancy (PVHO), establishing design, materials, and testing requirements for hyperbaric chambers.

Question 51: A diver ascending too rapidly may develop pulmonary barotrauma. Which of the following is NOT a recognized manifestation of this injury?

Arterial gas embolism (AGE)
Subcutaneous emphysema
Mediastinal emphysema
Decompression sickness Type I joint pain (Correct answer)

Correct answer: Decompression sickness Type I joint pain

Pulmonary barotrauma causes AGE, pneumothorax, mediastinal emphysema, and subcutaneous emphysema; Type I joint pain DCS is caused by bubble formation in tissues, not lung rupture.

Question 52: What is a near-miss report in CHS practice?

A near break-even report
A project near deadline
Documentation of an event that could have caused harm but did not (Correct answer)
An employee near target

Correct answer: Documentation of an event that could have caused harm but did not

Near-miss reports document events where harm almost occurred, providing data to prevent future incidents.

Question 53: The minimum safe distance (standoff distance) required between a hyperbaric facility and ignition sources, per NFPA 99, is primarily intended to:

Meet OSHA confined-space entry separation requirements
Allow emergency vehicles unrestricted access to all chamber entrances
Comply with CMS site-inspection building code requirements
Protect against fire spread if oxygen-enriched exhaust gases ignite outside the facility (Correct answer)

Correct answer: Protect against fire spread if oxygen-enriched exhaust gases ignite outside the facility

Oxygen exhaust venting from hyperbaric chambers creates an oxygen-enriched zone; standoff distances prevent this enriched atmosphere from reaching ignition sources.

Question 54: A patient with chronic carbon monoxide poisoning presents 36 hours after exposure. Which statement best describes the rationale for still offering HBOT?

HBO at this stage focuses on eliminating carboxyhemoglobin remaining in blood
HBO has no benefit beyond 6 hours post-exposure
HBO beyond 24 hours is only indicated for pregnant patients
Delayed HBO may still reduce the risk of delayed neurological sequelae (Correct answer)

Correct answer: Delayed HBO may still reduce the risk of delayed neurological sequelae

Even with delayed presentation, HBOT may reduce the incidence of delayed neurological syndrome by addressing CO bound to cytochrome oxidase and lipid peroxidation.

Question 55: Which clinical finding is most consistent with arterial gas embolism (AGE) in a SCUBA diver?

Fatigue developing 24 hours after a dive
Mild skin rash appearing 6 hours post-dive
Joint pain appearing 12 hours after surfacing
Sudden loss of consciousness immediately upon or within minutes of surfacing (Correct answer)

Correct answer: Sudden loss of consciousness immediately upon or within minutes of surfacing

AGE causes immediate neurological catastrophe on surfacing as air bubbles enter the pulmonary veins and travel to the cerebral circulation, producing rapid loss of consciousness or stroke-like symptoms.

Question 56: What does residual risk mean in CHS practice?

Risk remaining after all controls are implemented (Correct answer)
Initial risk before assessment
Risk affecting waste materials
Budget overrun risk

Correct answer: Risk remaining after all controls are implemented

Residual risk is the level remaining after practical controls are applied. Some is usually accepted as eliminating all risk is rarely feasible.

Question 57: In the context of hyperbaric medicine, what does the term 'on-gassing' refer to?

Spontaneous decompression of gas bubbles in a hyperbaric chamber
Oxygen delivery to hypoxic wound tissue
Carbon dioxide production during exertion at depth
Inert gas uptake by tissues during pressurization or bottom time (Correct answer)

Correct answer: Inert gas uptake by tissues during pressurization or bottom time

On-gassing describes the uptake of inert gases (nitrogen or helium) into body tissues as partial pressure increases during descent or bottom time.

Question 58: What is the primary reason hyperbaric oxygen is effective in carbon monoxide poisoning beyond simply displacing CO from hemoglobin?

It causes therapeutic hypothermia
It accelerates CO dissociation from intracellular myoglobin and cytochrome oxidase (Correct answer)
It increases 2,3-DPG levels
It stimulates the Haldane effect to increase CO binding

Correct answer: It accelerates CO dissociation from intracellular myoglobin and cytochrome oxidase

HBO2 accelerates CO dissociation from mitochondrial cytochrome oxidase and myoglobin, restoring cellular respiration beyond what normobaric oxygen achieves.

Question 59: What is the Fick principle as applied to oxygen delivery in hyperbaric physiology?

Oxygen consumption equals cardiac output multiplied by the arteriovenous oxygen difference (Correct answer)
Total oxygen content equals hemoglobin-bound plus dissolved oxygen
Dissolved oxygen in plasma equals PO2 multiplied by the solubility coefficient
Pressure at depth equals surface pressure plus hydrostatic pressure

Correct answer: Oxygen consumption equals cardiac output multiplied by the arteriovenous oxygen difference

The Fick principle states that VO2 = CO × (CaO2 − CvO2), linking oxygen consumption to cardiac output and the arteriovenous oxygen content difference.

Question 60: What is a work breakdown structure in CHS practice?

Hierarchical decomposition of deliverables into manageable work packages (Correct answer)
Team member roster
Organizational reporting diagram
Employee schedule report

Correct answer: Hierarchical decomposition of deliverables into manageable work packages

A WBS breaks total scope into progressively smaller components for easier estimation, scheduling, and tracking.

Question 61: Which physiological condition is a known predisposing factor that significantly increases the risk of CNS oxygen toxicity?

Well-controlled type 2 diabetes
Mild controlled hypothyroidism
Mild normocytic anemia
Hypercapnia (elevated CO2) (Correct answer)

Correct answer: Hypercapnia (elevated CO2)

Hypercapnia causes cerebral vasodilation, increasing cerebral blood flow and oxygen delivery to the brain, which lowers the seizure threshold for CNS oxygen toxicity.

Question 62: Middle ear squeeze (barotitis media) during HBO therapy is caused by:

Failure of the Eustachian tube to equalize pressure across the tympanic membrane (Correct answer)
Excessive oxygen delivery to cochlear tissues
Air bubble formation in the semicircular canals
Eustachian tube hypertension from rapid ascent

Correct answer: Failure of the Eustachian tube to equalize pressure across the tympanic membrane

Middle ear squeeze results when the Eustachian tube fails to open and allow pressure equalization, causing the tympanic membrane to deform under increasing chamber pressure.

Question 63: Which OSHA standard most directly applies to hyperbaric workers regarding compressed air work environments?

29 CFR 1910.146 — Permit-Required Confined Spaces
29 CFR 1910.134 — Respiratory Protection
29 CFR 1926.803 — Compressed Air (Correct answer)
29 CFR 1910.1030 — Bloodborne Pathogens

Correct answer: 29 CFR 1926.803 — Compressed Air

OSHA 29 CFR 1926.803 governs workers in compressed air environments, including hyperbaric tunneling and construction, establishing decompression requirements.

Question 64: What role do standard operating procedures play in CHS Patient Assessment & Evaluation?

Restricting creativity
Satisfying management only
Creating unnecessary paperwork
Ensuring consistency and quality through documented instructions (Correct answer)

Correct answer: Ensuring consistency and quality through documented instructions

SOPs provide standardized instructions ensuring consistent quality regardless of which qualified person performs the work.

Question 65: Type II (serious) DCS most commonly affects which body system, making early treatment with HBOT critical?

Hepatic system
Renal system
Spinal cord and central nervous system (Correct answer)
Gastrointestinal system

Correct answer: Spinal cord and central nervous system

Type II DCS frequently causes spinal cord and CNS injury from venous infarction and bubble emboli, presenting with paralysis, sensory deficits, or altered consciousness.

Question 66: What is the importance of continuing education for CHS professionals in Patient Assessment & Evaluation?

Filling time between engagements
Justifying higher fees
Only for new professionals
Maintaining current knowledge and adapting to industry changes (Correct answer)

Correct answer: Maintaining current knowledge and adapting to industry changes

Continuing education keeps professionals current with developments and best practices while meeting certification requirements.

Question 67: In CHS practice, what constitutes a conflict of interest?

A difference in project opinions
A disagreement between colleagues about procedures
When personal interests could compromise professional judgment (Correct answer)
A scheduling conflict between meetings

Correct answer: When personal interests could compromise professional judgment

A conflict of interest occurs when personal, financial, or other interests could potentially influence professional judgment and decisions.

Question 68: What does residual risk mean in CHS practice?

Risk remaining after all controls are implemented (Correct answer)
Budget overrun risk
Risk affecting waste materials
Initial risk before assessment

Correct answer: Risk remaining after all controls are implemented

Residual risk is the level remaining after practical controls are applied. Some is usually accepted as eliminating all risk is rarely feasible.

Question 69: What is the first step in CHS risk assessment?

Assigning blame
Purchasing insurance
Identifying potential hazards and threats (Correct answer)
Ignoring minor risks

Correct answer: Identifying potential hazards and threats

Risk assessment begins with systematic identification of all potential hazards, forming the foundation for all subsequent analysis.

Question 70: A patient undergoing HBOT for a chronic non-healing wound is also receiving radiation therapy. Why might the irradiated tissue respond poorly to conventional wound care?

Radiation accelerates wound healing by stimulating stem cells
Radiation causes obliterative endarteritis resulting in chronic tissue hypoxia and impaired healing (Correct answer)
Radiation directly kills all bacteria preventing infection
Radiation increases collagen overproduction causing fibrosis only

Correct answer: Radiation causes obliterative endarteritis resulting in chronic tissue hypoxia and impaired healing

Ionizing radiation damages small blood vessels (obliterative endarteritis), creating a hypoxic-hypovascular-hypocellular wound environment that impairs healing.

Question 71: How does professional liability insurance protect CHS practitioners?

Covering financial losses from claims of negligence or errors (Correct answer)
Paying health premiums
Protecting against equipment theft
Covering disaster damage

Correct answer: Covering financial losses from claims of negligence or errors

This insurance covers financial consequences of claims alleging negligence or mistakes in professional services.

Question 72: When evaluating a wound for HBO eligibility using TcPO2, measurements should ideally be taken with the probe placed:

At the dorsum of the foot regardless of wound location
On the contralateral limb as a control value
On periwound skin 1–3 cm from the wound edge (Correct answer)
Directly over the wound bed to measure tissue perfusion at the center

Correct answer: On periwound skin 1–3 cm from the wound edge

Periwound TcPO2 measured 1–3 cm from the wound margin provides the most clinically relevant oxygen tension data for predicting healing potential.

Question 73: Which wound measurement tool uses light reflection to provide a three-dimensional assessment of wound volume and surface area?

Standard wound ruler
Structured light or stereophotogrammetry imaging system (Correct answer)
Visual analog scale
Transparent acetate tracing

Correct answer: Structured light or stereophotogrammetry imaging system

Structured light and stereophotogrammetry systems capture 3D wound geometry non-contact, providing accurate volume and area measurements for tracking HBOT response.

Question 74: Which document must be completed before every hyperbaric treatment session to verify equipment readiness?

Patient insurance verification form
Pre-treatment equipment checklist (Correct answer)
Decompression sickness incident report
Annual maintenance log

Correct answer: Pre-treatment equipment checklist

A pre-treatment equipment checklist confirms that all chamber systems, safety devices, and emergency equipment are functional before each session.

Question 75: What is the primary purpose of air breaks during a hyperbaric oxygen treatment table?

To prevent CNS and pulmonary oxygen toxicity by reducing cumulative oxygen exposure (Correct answer)
To flush carbon dioxide buildup from the chamber atmosphere
To decompress the patient safely between oxygen breathing periods
To allow the patient time to equalize middle ear pressure

Correct answer: To prevent CNS and pulmonary oxygen toxicity by reducing cumulative oxygen exposure

Air breaks reduce the total oxygen dose and cumulative unit pulmonary toxicity dose (UPTD), protecting against both CNS seizures and pulmonary oxygen toxicity.

Question 76: After a hyperbaric facility experiences a patient loss of consciousness event inside the chamber, regulatory requirements typically mandate:

Immediate closure of the facility pending a state inspection
Filing a report with the FDA within 24 hours of the event
Completing an incident report, notifying the medical director, and conducting a root cause analysis (Correct answer)
Rescheduling all remaining patients to a different facility that day

Correct answer: Completing an incident report, notifying the medical director, and conducting a root cause analysis

Adverse events require incident reporting, medical director notification, and systematic root cause analysis per accreditation and facility policy.

Question 77: What is the role of oxygen concentration monitoring in hyperbaric therapy?

To regulate room temperature
To ensure patients are exposed to the correct oxygen levels (Correct answer)
To increase the speed of the therapy
To monitor heart rate

Correct answer: To ensure patients are exposed to the correct oxygen levels

Oxygen concentration monitoring is vital in hyperbaric therapy to ensure the patient receives the precise therapeutic dose of oxygen. Too low a concentration would render the treatment ineffective, while too high a concentration or prolonged exposure could lead to dangerous oxygen toxicity. Accurate monitoring allows for adjustments to maintain optimal and safe treatment parameters.

Question 78: What role do standard operating procedures play in CHS Pharmacology & Medication Management?

Ensuring consistency and quality through documented instructions (Correct answer)
Restricting creativity
Satisfying management only
Creating unnecessary paperwork

Correct answer: Ensuring consistency and quality through documented instructions

SOPs provide standardized instructions ensuring consistent quality regardless of which qualified person performs the work.

Question 79: Which laboratory or imaging finding most directly confirms the diagnosis of pulmonary barotrauma with pneumothorax in a diver?

Elevated troponin indicating cardiac injury
Chest radiograph showing air in the pleural space and mediastinum (Correct answer)
Elevated serum nitrogen level
Brain MRI showing diffusion restriction

Correct answer: Chest radiograph showing air in the pleural space and mediastinum

Chest X-ray demonstrating pleural air (pneumothorax) or mediastinal air (pneumomediastinum) confirms pulmonary overinflation injury, a critical finding before HBOT as tension pneumothorax must be addressed first.

Question 80: What is a records management audit in CHS?

Computer usage review
Reviewing practices to ensure compliance with policies (Correct answer)
Counting filing cabinets
Supplies inventory

Correct answer: Reviewing practices to ensure compliance with policies

This audit examines how records are created, stored, accessed, retained, and destroyed for compliance.

Question 81: A hyperbaric technologist notices that a patient's transcutaneous oxygen monitor (TCOM) reading drops significantly during a 2.4 ATA oxygen session. The MOST likely clinical explanation is:

Local tissue ischemia or vascular compromise reducing oxygen delivery to that region
CNS oxygen toxicity diverting blood flow away from peripheral tissues
Equipment malfunction caused by high ambient pressure affecting sensor accuracy
Hyperoxic vasoconstriction increasing oxygen delivery so the sensor saturates and under-reads (Correct answer)

Correct answer: Hyperoxic vasoconstriction increasing oxygen delivery so the sensor saturates and under-reads

Hyperoxia causes peripheral vasoconstriction; the resulting decreased blood flow to the area being monitored can reduce the TCOM reading despite high systemic PO2.

Question 82: What is a near-miss report in CHS practice?

An employee near target
Documentation of an event that could have caused harm but did not (Correct answer)
A project near deadline
A near break-even report

Correct answer: Documentation of an event that could have caused harm but did not

Near-miss reports document events where harm almost occurred, providing data to prevent future incidents.

Question 83: What is the significance of emergency training for hyperbaric specialists?

To handle emergencies and ensure safety (Correct answer)
To increase therapy time
To ensure equipment malfunctions
To reduce the number of patients

Correct answer: To handle emergencies and ensure safety

Emergency training is vital for hyperbaric specialists because it equips them with the knowledge and skills to respond effectively to critical situations that may arise during therapy. This preparedness is essential for mitigating risks, ensuring patient safety, and managing potential complications in a high-pressure environment.

Question 84: A CHS is treating a diver with Type II DCS who is also taking aspirin. What is the rationale for using aspirin as an adjunct in DCS management?

Aspirin increases nitrogen off-gassing from tissues
Aspirin's antiplatelet effect reduces platelet aggregation on bubble surfaces, mitigating secondary thrombosis (Correct answer)
Aspirin prevents oxygen toxicity during HBOT
Aspirin directly dissolves nitrogen bubbles

Correct answer: Aspirin's antiplatelet effect reduces platelet aggregation on bubble surfaces, mitigating secondary thrombosis

Gas bubbles trigger platelet aggregation and complement activation; aspirin inhibits platelet function to reduce the secondary thrombotic and inflammatory injury superimposed on bubble-mediated damage.

Question 85: What is the term for the HBOT-approved condition characterized by bone death due to radiation damage?

Osteomyelitis
Stress fracture
Osteoradionecrosis (Correct answer)
Avascular necrosis

Correct answer: Osteoradionecrosis

Osteoradionecrosis is the death of bone resulting from radiation-induced vascular insufficiency, and it is a UHMS-approved indication for HBOT.

Question 86: A patient receiving HBOT for osteomyelitis has a serum glucose of 380 mg/dL prior to a scheduled session. What is the correct course of action?

Delay treatment until glucose is below 250 mg/dL and optimize glycemic control (Correct answer)
Administer insulin inside the chamber and monitor during the dive
Cancel all future HBO sessions until diabetes is controlled
Proceed with treatment as hyperglycemia is not a contraindication

Correct answer: Delay treatment until glucose is below 250 mg/dL and optimize glycemic control

Severe hyperglycemia impairs leukocyte function and wound healing; delaying treatment until glucose is better controlled maximizes therapeutic benefit and patient safety.

Question 87: Central nervous system oxygen toxicity in hyperbaric therapy is most likely to occur when oxygen partial pressure (PO2) exceeds:

0.6 ATA
2.0 ATA
1.6 ATA (Correct answer)
1.0 ATA

Correct answer: 1.6 ATA

CNS oxygen toxicity risk rises sharply above a PO2 of 1.6 ATA, which is why most HBO protocols use 2.0–2.4 ATA with air breaks.

Question 88: A patient with necrotizing fasciitis is brought to the hyperbaric facility postoperatively. Under what condition should HBOT NOT delay operative management?

When the patient's WBC is above 20,000
When the patient is hemodynamically unstable on vasopressors
When surgical debridement has not yet been performed (Correct answer)
When gas is visible on imaging beyond the initial wound site

Correct answer: When surgical debridement has not yet been performed

HBOT is an adjunct to — never a substitute for — surgical debridement; definitive operative treatment must always take priority over scheduling a hyperbaric session.

Question 89: A hyperbaric facility must conduct fire drills at minimum every:

6 months per UHMS guidelines
24 months if no incidents have occurred
3 months per OSHA 1926.803
12 months per NFPA 99 and accreditation standards (Correct answer)

Correct answer: 12 months per NFPA 99 and accreditation standards

NFPA 99 and major accreditation bodies (TJC, ACHC) require hyperbaric facilities to conduct emergency response drills at least annually.

Question 90: What are principles of good documentation in CHS?

Only document positives
Accuracy, completeness, timeliness, objectivity, and legibility (Correct answer)
Include personal opinions
Speed is the only factor

Correct answer: Accuracy, completeness, timeliness, objectivity, and legibility

Good documentation must be accurate, complete, timely, objective, and legible.

Question 91: Why must static electricity be controlled inside a hyperbaric chamber?

Patient clothing becomes permanently magnetized at pressure
Static electricity disrupts the oxygen analyzer calibration
Static discharge can ignite oxygen-enriched atmospheres or combustible materials inside the chamber (Correct answer)
Static buildup damages the acrylic viewport material

Correct answer: Static discharge can ignite oxygen-enriched atmospheres or combustible materials inside the chamber

In oxygen-enriched environments, even a small electrostatic discharge can provide sufficient ignition energy to start a fire with materials that would not normally be flammable.

Question 92: What is a critical safety measure when using hyperbaric oxygen therapy?

Ensuring non-flammable materials are used (Correct answer)
Using flammable materials
Increasing chamber pressure
Allowing smoking

Correct answer: Ensuring non-flammable materials are used

Hyperbaric chambers operate with high concentrations of oxygen, which significantly increases the risk of fire. Oxygen is a powerful oxidizer, making flammable materials ignite much more easily and burn more intensely. Therefore, strictly ensuring that only non-flammable or oxygen-compatible materials are present in and around the chamber is a critical safety measure to prevent catastrophic fires.

Question 93: According to UHMS guidelines, which staff credential is required to supervise inside a multi-place hyperbaric chamber during patient treatment?

An EMT-Basic with chamber orientation
A certified SCUBA diver with first-aid certification
A Certified Hyperbaric Technologist (CHT) or Registered Nurse trained in hyperbaric medicine (Correct answer)
Any licensed physician regardless of hyperbaric training

Correct answer: A Certified Hyperbaric Technologist (CHT) or Registered Nurse trained in hyperbaric medicine

UHMS and accreditation standards require that an inside attendant be a trained CHT or equivalently credentialed clinical professional.

Question 94: What are record retention policies in CHS practice?

Paper storage only
Rules defining how long records must be kept and when destroyed (Correct answer)
Destroying records yearly
Keeping everything forever

Correct answer: Rules defining how long records must be kept and when destroyed

Retention policies establish consistent guidelines based on legal requirements and business needs.

Question 95: Which treatment table is most commonly used for treating arterial gas embolism (AGE) in the United States?

US Navy Treatment Table 6 (Correct answer)
US Navy Treatment Table 9
Comex Table 30
US Navy Treatment Table 5

Correct answer: US Navy Treatment Table 6

US Navy Treatment Table 6 is the standard first-line treatment for arterial gas embolism and serious decompression sickness, involving oxygen breathing at 2.8 ATA.

Question 96: What is the primary pathophysiological mechanism of decompression sickness (DCS)?

Formation of nitrogen gas bubbles in tissues and blood during rapid ascent (Correct answer)
Nitrogen narcosis progressing to tissue injury
Carbon dioxide retention from inadequate ventilation underwater
Oxygen toxicity from excessive O2 partial pressure during ascent

Correct answer: Formation of nitrogen gas bubbles in tissues and blood during rapid ascent

Rapid ascent causes dissolved nitrogen in tissues to come out of solution and form bubbles, which physically obstruct vessels, compress nerves, and trigger inflammatory cascades.

Question 97: What is the Wagner Classification Grade that typically represents a full-thickness wound with exposed tendon or joint capsule in a diabetic patient?

Grade 2
Grade 4
Grade 3 (Correct answer)
Grade 1

Correct answer: Grade 3

Wagner Grade 3 denotes a deep ulcer with abscess, osteomyelitis, or joint sepsis, including wounds exposing tendon, capsule, or bone.

Question 98: Which paranasal sinus is most commonly affected by sinus squeeze (sinus barotrauma)?

Maxillary sinus (Correct answer)
Frontal sinus
Ethmoid sinus
Sphenoid sinus

Correct answer: Maxillary sinus

The maxillary sinuses are most frequently affected by sinus squeeze because of their size and the high prevalence of ostial obstruction from nasal congestion or polyps.

Question 99: What does professional competency require of a CHS practitioner?

Maintaining current knowledge through continuing education (Correct answer)
Relying solely on original training
Learning only during initial schooling
Accepting all work regardless of qualifications

Correct answer: Maintaining current knowledge through continuing education

Professional competency requires ongoing education, staying current with developments, and practicing only within qualified areas.

Question 100: What is the primary mechanism by which HBOT promotes wound healing?

Reduces wound temperature to prevent bacterial growth
Directly kills bacteria by high pressure alone
Increases tissue oxygen tension to stimulate angiogenesis and collagen synthesis (Correct answer)
Removes necrotic tissue through osmotic pressure

Correct answer: Increases tissue oxygen tension to stimulate angiogenesis and collagen synthesis

HBOT raises tissue pO2 levels, which drives fibroblast proliferation, collagen synthesis, and new blood vessel formation (angiogenesis) essential for wound repair.

Certified Hyperbaric Specialist (CHS) Exam

This certification recognizes individuals with advanced knowledge and skills in hyperbaric oxygen therapy (HBOT) operations, patient care, and safety protocols.

100

Questions

120 min

Time Limit

70%

To Pass

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