Certified Hyperbaric Technologist (CHT) Exam — Questions and Answers

Question 1: Why is hydration important before HBOT?

To avoid dizziness and hypotension during treatment (Correct answer)
It improves memory.
To lower oxygen toxicity.
To speed up decompression.

Correct answer: To avoid dizziness and hypotension during treatment

Hydration is important before HBOT to maintain adequate blood volume and prevent orthostatic hypotension and dizziness. Dehydration can lead to a drop in blood pressure, especially when patients change positions or experience the physiological effects of hyperbaric treatment. Ensuring proper hydration helps stabilize the patient's cardiovascular system, contributing to a safer and more comfortable experience during therapy.

Question 2: What is the primary reason 100% oxygen is used instead of air during hyperbaric therapy?

To prevent nitrogen narcosis as the sole benefit
Oxygen is less expensive than compressed air
100% O2 maximizes dissolved oxygen in tissues via Henry's Law for therapeutic effect (Correct answer)
To reduce fire risk inside the chamber

Correct answer: 100% O2 maximizes dissolved oxygen in tissues via Henry's Law for therapeutic effect

Breathing 100% O2 maximizes the partial pressure of oxygen, driving dissolution into plasma and ischemic tissues via Henry's Law to deliver the therapeutic hyperoxic dose.

Question 3: How does HBOT support wound healing?

By increasing tissue oxygenation and supporting angiogenesis (Correct answer)
By causing inflammation.
By reducing oxygen to the tissue.
By decreasing collagen production.

Correct answer: By increasing tissue oxygenation and supporting angiogenesis

HBOT significantly aids wound healing by dramatically increasing the oxygen supply to compromised tissues, which is vital for cellular metabolism and repair. This elevated oxygen promotes fibroblast activity, collagen synthesis, and the formation of new blood vessels (angiogenesis), all essential processes for closing wounds and restoring tissue integrity. It also enhances the body's ability to fight infection, accelerating the healing process.

Question 4: Why is stakeholder communication important in hyperbaric chamber emergency procedures?

It ensures alignment of expectations and facilitates collaborative decision-making (Correct answer)
It slows down the implementation process unnecessarily
It is only needed when major changes are being implemented
It is only relevant for management-level positions

Correct answer: It ensures alignment of expectations and facilitates collaborative decision-making

Stakeholder communication ensures everyone involved has aligned expectations and can contribute to informed, collaborative decision-making.

Question 5: At 2 ATA breathing 100% oxygen, the partial pressure of oxygen is approximately:

760 mmHg
1520 mmHg (Correct answer)
2280 mmHg
380 mmHg

Correct answer: 1520 mmHg

At 2 ATA, PO2 = 2 × 760 mmHg = 1520 mmHg, since partial pressure scales directly with absolute pressure.

Question 6: Which clinical finding would MOST strongly indicate a need to abort a hyperbaric treatment and decompress?

Patient report of mild claustrophobia
Mild sinus squeeze pain relieved by pausing compression
Tonic-clonic seizure activity in the patient (Correct answer)
Patient coughing intermittently during oxygen breathing

Correct answer: Tonic-clonic seizure activity in the patient

A generalized tonic-clonic seizure is a medical emergency requiring controlled ascent and treatment termination to prevent injury.

Question 7: When preparing a critically ill ICU patient for hyperbaric oxygen therapy, which piece of equipment requires SPECIAL consideration before chamber entry?

Cuffed endotracheal tube with air-filled cuff (Correct answer)
Standard pulse oximetry probe
Peripheral IV line
ECG monitoring leads

Correct answer: Cuffed endotracheal tube with air-filled cuff

Air-filled cuffs compress under pressure and expand during decompression, risking extubation or tracheal damage; cuffs must be filled with sterile water or saline.

Question 8: During an initial evaluation, what should be documented first?

Billing codes and insurance information
Patient demographics and chief complaint (Correct answer)
Discharge planning details
Treatment plan and expected outcomes

Correct answer: Patient demographics and chief complaint

Patient demographics and chief complaint are documented first to establish identity and the primary reason for seeking care, guiding all subsequent assessment activities.

Question 9: Gas gangrene (clostridial myonecrosis) benefits from HBOT because:

Hyperoxia is directly bacteriostatic/bactericidal to anaerobic Clostridium and inhibits alpha-toxin production (Correct answer)
Oxygen prevents further gas formation in infected tissue
HBOT replaces the need for emergent surgical debridement
High pressure physically destroys Clostridium spores

Correct answer: Hyperoxia is directly bacteriostatic/bactericidal to anaerobic Clostridium and inhibits alpha-toxin production

High tissue oxygen tensions are toxic to obligate anaerobes like Clostridium perfringens and inhibit alpha-toxin production, making HBOT a valuable adjunct to surgery and antibiotics.

Question 10: A patient with COPD and known CO2 retention (hypercapnia) presents for HBO therapy. The primary concern regarding oxygen toxicity is that hypercapnia:

Blocks oxygen from binding to hemoglobin in the lungs
Makes ear equalization impossible for the patient
Lowers the seizure threshold, increasing CNS oxygen toxicity risk (Correct answer)
Prevents adequate chamber pressurization in COPD patients

Correct answer: Lowers the seizure threshold, increasing CNS oxygen toxicity risk

Hypercapnia (elevated CO2) is a recognized risk factor that lowers the threshold for CNS oxygen toxicity seizures, making careful patient selection and heightened monitoring essential.

Question 11: State health department regulations for hyperbaric facilities most commonly mirror which national standards?

OSHA 1910 Subpart T only
NFPA 99 and Joint Commission standards (Correct answer)
US Navy Dive Manual requirements
ISO 13485 quality management requirements

Correct answer: NFPA 99 and Joint Commission standards

Most state health departments adopt NFPA 99 and, where applicable, Joint Commission or similar accreditation standards as the basis for hyperbaric facility licensure requirements.

Question 12: Which assessment tool is most commonly used to evaluate a patient's functional status?

Insurance claim forms
Standardized functional capacity scales (Correct answer)
Patient self-report without verification
Visual inspection only

Correct answer: Standardized functional capacity scales

Standardized functional capacity scales provide objective, reproducible measurements of patient functional status that can be compared over time.

Question 13: Which type of radiation injury is an approved UHMS indication for HBOT?

Acute radiation skin erythema within the first week
Delayed radiation necrosis of soft tissue and bone (osteoradionecrosis) (Correct answer)
Radiation-induced alopecia
Radiation-induced nausea and vomiting

Correct answer: Delayed radiation necrosis of soft tissue and bone (osteoradionecrosis)

Delayed radiation necrosis (soft tissue radionecrosis and osteoradionecrosis) is UHMS-approved because radiation causes progressive vascular obliteration leading to chronic tissue hypoxia.

Question 14: What should be done if an error is discovered in existing records?

Draw a single line through the error, note the correction, date, and initial (Correct answer)
Remove the page and rewrite it
Ignore the error if it seems minor
Use correction fluid to cover the error

Correct answer: Draw a single line through the error, note the correction, date, and initial

The correct method is a single line through the error with a dated and initialed correction, preserving the original entry for legal and audit purposes.

Question 15: In hyperbaric medicine, the concept of 'therapeutic privilege' — withholding information to avoid upsetting a patient — is generally considered:

Ethically problematic because it undermines patient autonomy and informed decision-making (Correct answer)
Required under HIPAA for patients with mental health diagnoses
Ethically acceptable if the physician orders it
A standard part of informed consent for anxious patients

Correct answer: Ethically problematic because it undermines patient autonomy and informed decision-making

Therapeutic privilege is widely rejected in modern medical ethics because withholding material information violates patient autonomy and the right to informed consent.

Question 16: A patient with a history of spontaneous pneumothorax presents for hyperbaric oxygen therapy. Which action is MOST appropriate before initiating treatment?

Limit treatment to 1.5 ATA only
Administer bronchodilators prior to compression
Proceed with treatment at reduced pressure
Obtain physician clearance and verify resolution of the pneumothorax (Correct answer)

Correct answer: Obtain physician clearance and verify resolution of the pneumothorax

A history of spontaneous pneumothorax is a relative contraindication; confirmed resolution and physician clearance are required before HBO therapy.

Question 17: When transcribing a physician's handwritten hyperbaric treatment order that is difficult to read, the CHT should:

Ask a colleague to interpret the handwriting
Contact the physician to clarify the order before documenting or proceeding (Correct answer)
Interpret the order based on the most likely clinical intent and proceed
Skip the unclear portion and document only what is legible

Correct answer: Contact the physician to clarify the order before documenting or proceeding

Unclear orders must be clarified directly with the ordering physician before treatment proceeds; guessing creates patient safety risks and liability.

Question 18: The 'oxygen window' in hyperbaric therapy refers to:

The viewing port on a hyperbaric chamber
The partial pressure gradient that facilitates inert gas (nitrogen) elimination from tissues (Correct answer)
The therapeutic range of oxygen concentrations
The safe time window for oxygen breathing

Correct answer: The partial pressure gradient that facilitates inert gas (nitrogen) elimination from tissues

The oxygen window is the pressure differential created when tissues consume oxygen, replacing it with a gas-free space that accelerates nitrogen elimination without bubble formation.

Question 19: Which of the following is recognized as a RELATIVE contraindication (not absolute) to HBO therapy?

History of prior spontaneous pneumothorax (now resolved) (Correct answer)
Active uncontrolled life-threatening hemorrhage
Active concurrent treatment with bleomycin chemotherapy
Untreated tension pneumothorax

Correct answer: History of prior spontaneous pneumothorax (now resolved)

A history of spontaneous pneumothorax is a relative contraindication; the risk of recurrence during HBO must be assessed and prophylactic measures considered, but treatment may still proceed.

Question 20: When transitioning between treatment phases, what is essential?

Make changes without updating records
Document the rationale for change and update goals accordingly (Correct answer)
Let the patient decide all treatment parameters
Continue the same approach indefinitely

Correct answer: Document the rationale for change and update goals accordingly

Documenting the rationale for treatment phase changes and updating goals ensures continuity of care, clear communication, and appropriate progress tracking.

Question 21: Nitrogen narcosis while breathing air in a hyperbaric environment typically becomes clinically apparent around:

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

Correct answer: 4.0 ATA

Nitrogen narcosis generally becomes clinically apparent around 4 ATA (approximately 99 fsw) when breathing air, though individual susceptibility varies.

Question 22: Carbon monoxide (CO) causes toxicity primarily by binding to hemoglobin with an affinity approximately how many times greater than oxygen?

10 times
1,000 times
50 times
240 times (Correct answer)

Correct answer: 240 times

CO binds hemoglobin with ~240 times the affinity of O₂, forming carboxyhemoglobin (COHb) and preventing O₂ transport, which is why HBOT is the definitive treatment.

Question 23: Which principle describes how gas molecules dissolve in a liquid in proportion to their partial pressure, directly underlying the physics of HBOT tissue oxygenation?

Dalton's Law
Henry's Law (Correct answer)
Charles's Law
Boyle's Law

Correct answer: Henry's Law

Henry's Law states that the amount of gas dissolved in a liquid is proportional to its partial pressure, explaining increased plasma oxygen dissolution at hyperbaric pressures.

Question 24: Henry's Law is most relevant in hyperbaric medicine because it explains:

Why body temperature affects gas behavior
Why different gases diffuse at different rates
Why more oxygen dissolves in blood at higher pressures (Correct answer)
Why gas volumes decrease under pressure

Correct answer: Why more oxygen dissolves in blood at higher pressures

Henry's Law states that the amount of gas dissolved in a liquid is proportional to its partial pressure, explaining increased plasma oxygen dissolution during HBOT.

Question 25: A gas bubble measuring 1 cm³ at 1 ATA will measure approximately what volume at 3 ATA (Boyle's Law)?

0.33 cm³ (Correct answer)
3.0 cm³
0.67 cm³
0.5 cm³

Correct answer: 0.33 cm³

Applying Boyle's Law (P₁V₁ = P₂V₂): 1 × 1 = 3 × V₂, giving V₂ = 0.33 cm³.

Question 26: What must be completed before using any specialized equipment?

Read the manual only during first use
Turn it on and begin operation immediately
Check only if the equipment looks damaged
Verify proper calibration and review safety procedures (Correct answer)

Correct answer: Verify proper calibration and review safety procedures

Verifying calibration and reviewing safety procedures before each use ensures accurate results and prevents equipment-related injuries or errors.

Question 27: A fellow hyperbaric technician confides they have been coming to work impaired by alcohol. What is the most ethical response?

Cover for the colleague to preserve workplace harmony
Advise the colleague to only perform administrative tasks while impaired
Wait to see if the impairment affects patient care before acting
Encourage the colleague to self-report and report to the supervisor if they do not (Correct answer)

Correct answer: Encourage the colleague to self-report and report to the supervisor if they do not

Impairment poses direct patient safety risk; the technician must encourage self-reporting and escalate if that does not occur to protect patients.

Question 28: A post-treatment assessment reveals that a patient experienced tinnitus and muffled hearing after their first HBO session. The technician should document this as likely:

Middle ear barotrauma (otic barotrauma) (Correct answer)
Sensorineural hearing loss from noise
Labyrinthine decompression sickness
Inner ear oxygen toxicity

Correct answer: Middle ear barotrauma (otic barotrauma)

Tinnitus and muffled hearing after a dive are hallmark symptoms of middle ear barotrauma caused by inadequate pressure equalization.

Question 29: Which medication is considered a major contraindication with HBO therapy because it inhibits superoxide dismutase, potentially worsening oxygen free radical damage?

Metformin
Warfarin (Coumadin)
Prednisone
Disulfiram (Antabuse) (Correct answer)

Correct answer: Disulfiram (Antabuse)

Disulfiram inhibits superoxide dismutase and other antioxidant enzymes, reducing the body's ability to neutralize reactive oxygen species generated during HBO, dramatically increasing toxicity risk.

Question 30: When documenting a hyperbaric treatment session, which element is MOST critical to record for medicolegal and continuity-of-care purposes?

Patient tolerance, vital signs at intervals, any adverse events, and treatment parameters (pressure, duration, oxygen percentage) (Correct answer)
The names of all staff present outside the chamber
The ambient temperature of the hyperbaric suite
The brand name of the chamber used

Correct answer: Patient tolerance, vital signs at intervals, any adverse events, and treatment parameters (pressure, duration, oxygen percentage)

Comprehensive documentation including patient response, vital signs, adverse events, and all treatment parameters is essential for patient safety and medicolegal compliance.

Question 31: A patient scheduled for HBO therapy has a serum carboxyhemoglobin (COHb) level of 35%. This finding is MOST consistent with:

Methemoglobinemia
Chronic cigarette smoking
Acute carbon monoxide poisoning (Correct answer)
Polycythemia vera

Correct answer: Acute carbon monoxide poisoning

COHb levels above 25-30% are consistent with significant acute CO poisoning requiring urgent hyperbaric oxygen treatment.

Question 32: The minimum safe distance for an oxygen storage rack from the hyperbaric chamber hull, as generally required by NFPA 99, is primarily intended to:

Comply with electrical code clearances
Limit fire spread from an oxygen-fed fire to the chamber structure (Correct answer)
Allow technician access for routine maintenance
Reduce noise from high-pressure cylinder regulators

Correct answer: Limit fire spread from an oxygen-fed fire to the chamber structure

Separation distances protect the chamber structure and occupants from fire and heat if an oxygen-fed fire originates at the storage rack.

Question 33: A patient with claustrophobia is scheduled for a monoplace HBO treatment. Which intervention is MOST effective for preventing treatment interruption?

Allow the patient to tour and practice in the chamber before treatment, using anxiolytic medication as prescribed (Correct answer)
Blindfold the patient to reduce visual stimulation
Dim chamber lights and restrict all communication during treatment
Schedule the patient for multiplace chamber treatment only

Correct answer: Allow the patient to tour and practice in the chamber before treatment, using anxiolytic medication as prescribed

Pre-treatment familiarization with the chamber environment combined with physician-prescribed anxiolytics significantly reduces claustrophobic reactions.

Question 34: Pulmonary oxygen toxicity (Lorrain Smith effect) results primarily from:

Progressive lung injury from prolonged exposure to elevated partial pressures of oxygen (Correct answer)
Excess surfactant production by type II pneumocytes
Oxygen-induced vasoconstriction of the pulmonary microvasculature
Acute bronchospasm triggered by cold dry oxygen inhalation

Correct answer: Progressive lung injury from prolonged exposure to elevated partial pressures of oxygen

The Lorrain Smith effect describes progressive pulmonary injury from prolonged high-oxygen breathing, leading to inflammation, alveolar damage, and decreased vital capacity.

Question 35: Equipment calibration records for a hyperbaric chamber oxygen analyzer should be maintained for at least:

1 year only
30 days
6 months
The life of the equipment plus applicable regulatory retention period (Correct answer)

Correct answer: The life of the equipment plus applicable regulatory retention period

Equipment calibration and maintenance records should be retained for the life of the equipment plus the facility's applicable regulatory retention period to demonstrate ongoing compliance.

Question 36: Which skin finding on pre-treatment assessment would be MOST consistent with arterial insufficiency contributing to a chronic wound?

Weeping, hyperpigmented skin with varicosities
Hairless, shiny, cool skin with dependent rubor and absent pedal pulses (Correct answer)
Dependent edema and brownish discoloration of the lower leg
Pitting edema with brawny induration

Correct answer: Hairless, shiny, cool skin with dependent rubor and absent pedal pulses

Hairless, shiny, cool skin with rubor on dependency and absent pulses are classic signs of peripheral arterial disease causing tissue ischemia.

Question 37: Which NFPA document specifically addresses hyperbaric facilities and their fire safety requirements?

NFPA 99 (Correct answer)
NFPA 25
NFPA 101
NFPA 13

Correct answer: NFPA 99

NFPA 99, Health Care Facilities Code, contains Chapter 14 which governs hyperbaric facility fire safety and construction requirements.

Question 38: At 3 ATA breathing 100% O2, approximately how much oxygen is dissolved in plasma?

4.5 mL O2/100 mL blood
0.3 mL O2/100 mL blood
2.4 mL O2/100 mL blood
6.6 mL O2/100 mL blood (Correct answer)

Correct answer: 6.6 mL O2/100 mL blood

At 3 ATA with 100% O2, PO2 ≈ 2280 mmHg; using the solubility coefficient of 0.003 mL/100 mL/mmHg, dissolved O2 ≈ 6.6 mL/100 mL — enough to sustain resting tissues without hemoglobin.

Question 39: Which patient presentation is the best indicator that a hyperbaric wound-healing treatment course is producing clinical benefit?

Measurable reduction in wound size and improved transcutaneous oxygen tension (TcPO2) (Correct answer)
Normalization of serum glucose in diabetic patients
Subjective report of reduced pain only
Complete absence of infection signs after one treatment

Correct answer: Measurable reduction in wound size and improved transcutaneous oxygen tension (TcPO2)

Objective wound size reduction and improved TcPO2 readings confirm that HBO is enhancing tissue oxygenation and driving healing.

Question 40: According to Boyle's Law, if pressure in a hyperbaric chamber doubles, the volume of a trapped gas will:

Quadruple
Double
Halve (Correct answer)
Remain unchanged

Correct answer: Halve

Boyle's Law states that at constant temperature, pressure and volume are inversely proportional, so doubling pressure halves the gas volume.

Question 41: The 'chain of custody' concept in hyperbaric documentation primarily refers to:

The sequence of physician approvals for treatment
The order in which treatments are scheduled
Tracking who has accessed and modified a medical record (Correct answer)
The handoff of patients between shifts

Correct answer: Tracking who has accessed and modified a medical record

Chain of custody in documentation refers to the traceable, unbroken record of who accessed, reviewed, or modified a document, which is critical for legal integrity.

Question 42: Which anatomical structure separates the right and left ventricles and, if defective, can cause paradoxical gas embolism in hyperbaric patients?

Interatrial septum
Interventricular septum
Tricuspid valve
Patent foramen ovale (Correct answer)

Correct answer: Patent foramen ovale

A patent foramen ovale (PFO) allows venous gas emboli to cross directly into arterial circulation, causing paradoxical arterial gas embolism.

Question 43: Why is communication equipment essential in multi-place chambers?

To allow communication between staff and patients (Correct answer)
To monitor oxygen purity.
To record sessions.
For background music.

Correct answer: To allow communication between staff and patients

Communication equipment is essential in multi-place hyperbaric chambers to facilitate continuous interaction between the chamber operator (staff) and the patients inside. This allows staff to monitor patient comfort, address concerns, provide instructions, and respond to any medical needs or emergencies promptly. Clear and constant communication is vital for patient safety and effective treatment delivery within the enclosed environment.

Question 44: Carbon monoxide poisoning is treated with HBOT because:

HBOT prevents cerebral edema by reducing intracranial pressure
High pressure physically destroys CO molecules
Oxygen at high partial pressure competitively displaces CO from hemoglobin, reducing carboxyhemoglobin half-life from ~5 hours to ~20 minutes (Correct answer)
Increased pressure forces CO out through the lungs faster

Correct answer: Oxygen at high partial pressure competitively displaces CO from hemoglobin, reducing carboxyhemoglobin half-life from ~5 hours to ~20 minutes

At 2.4–3 ATA, high PO2 competitively displaces CO from hemoglobin and myoglobin, dramatically accelerating CO elimination and reducing delayed neurological injury.

Question 45: How does understanding tissue healing phases improve practice?

It only matters for surgical wounds
It guides appropriate treatment timing and technique selection (Correct answer)
It has no effect on treatment outcomes
It is relevant only in hospital settings

Correct answer: It guides appropriate treatment timing and technique selection

Understanding healing phases allows practitioners to select appropriate timing and techniques for each stage, optimizing recovery and preventing re-injury.

Question 46: A patient requests access to their hyperbaric treatment records. Under HIPAA, the facility must provide access within:

90 days
30 days (with a possible 30-day extension) (Correct answer)
60 days
7 days

Correct answer: 30 days (with a possible 30-day extension)

HIPAA requires covered entities to provide patients access to their records within 30 days, with one permissible 30-day extension if needed.

Question 47: The partial pressure of oxygen (PO2) at which CNS oxygen toxicity risk significantly increases is above:

1.6 ATA (Correct answer)
3.0 ATA
1.0 ATA
0.5 ATA

Correct answer: 1.6 ATA

CNS oxygen toxicity risk increases significantly when PO2 exceeds 1.6 ATA, which is why most therapeutic HBOT protocols are designed to stay at or below this threshold.

Question 48: The primary mechanism by which HBOT stimulates angiogenesis in chronic wounds is:

Causing mild thermal injury that triggers a repair response
Increasing systemic blood pressure to force new vessel formation
Directly injecting oxygen molecules into capillary walls
Cyclic hyperoxygenation followed by relative hypoxia upregulates VEGF and HIF-1α between sessions (Correct answer)

Correct answer: Cyclic hyperoxygenation followed by relative hypoxia upregulates VEGF and HIF-1α between sessions

The contrast between high in-chamber PO2 and relative hypoxia between sessions creates a cycling effect that upregulates VEGF and HIF-1α, driving therapeutic angiogenesis.

Question 49: Under NFPA 99 requirements, who is responsible for approving materials and equipment brought into a Class A hyperbaric chamber?

The patient or diver themselves
The local fire marshal
A qualified hyperbaric physician or safety director (Correct answer)
The chamber manufacturer's representative

Correct answer: A qualified hyperbaric physician or safety director

NFPA 99 places responsibility on the facility's qualified hyperbaric physician or safety director to approve all materials and equipment for use inside the chamber.

Question 50: A patient with an implanted pacemaker presents for HBO therapy. The technician should FIRST:

Verify that the pacemaker model is rated as pressure-stable and consult cardiology (Correct answer)
Refuse treatment as pacemakers are an absolute contraindication
Place the patient in a multiplace chamber only
Increase chamber pressure slowly to avoid pacemaker interference

Correct answer: Verify that the pacemaker model is rated as pressure-stable and consult cardiology

Most modern pacemakers are pressure-stable, but specific model verification and cardiologist clearance are required before HBO treatment.

Question 51: Which infection control practice is specifically required by CDC guidelines when handling linens soiled with blood from hyperbaric patients?

Roll or fold linens inward and place in leak-proof bag without shaking (Correct answer)
Shake linens to remove debris before bagging
Allow linens to air dry before bagging
Sort soiled linens at point of collection by soil type

Correct answer: Roll or fold linens inward and place in leak-proof bag without shaking

CDC guidelines require soiled linens to be rolled or folded inward and placed in leak-proof bags at the point of use—shaking or sorting is prohibited to prevent aerosol generation.

Question 52: How soon after a service or session should documentation be completed?

Within one week
At the end of the month
Only when an audit is scheduled
As soon as possible, ideally within 24 hours (Correct answer)

Correct answer: As soon as possible, ideally within 24 hours

Prompt documentation, ideally within 24 hours, ensures accuracy of recorded information and meets professional and legal standards.

Question 53: Which document serves as the primary legal record of a hyperbaric treatment session?

The patient treatment record/chart (Correct answer)
The facility incident report
The equipment maintenance log
The chamber operator daily checklist

Correct answer: The patient treatment record/chart

The patient treatment record is the primary legal document capturing all clinical decisions, vital signs, and treatment parameters for each session.

Question 54: During multiplace chamber operations, the intercommunication system fails mid-treatment. Per NFPA 99 and UHMS guidelines, the operator should:

Increase monitoring frequency and continue without interruption
Continue treatment using predetermined hand signals only
Terminate the treatment immediately by performing an emergency ascent
Establish an alternative communication method before continuing and follow facility emergency protocols (Correct answer)

Correct answer: Establish an alternative communication method before continuing and follow facility emergency protocols

Facilities must have backup communication plans; an alternative means must be established and verified before continuing patient treatment.

Question 55: What precaution should be taken with diabetic patients in HBOT?

Limit oxygen intake.
Monitor blood glucose regularly (Correct answer)
Ignore sugar levels.
Discontinue insulin.

Correct answer: Monitor blood glucose regularly

Diabetic patients undergoing HBOT require careful monitoring of their blood glucose levels because hyperbaric oxygen can sometimes cause a temporary drop in blood sugar. Hypoglycemia can be dangerous, especially in a hyperbaric environment where symptoms might be masked or difficult to manage. Regular monitoring ensures patient safety and allows for prompt intervention if glucose levels become too low.

Question 56: HBO-induced seizures due to CNS oxygen toxicity are best characterized as:

Life-threatening events requiring immediate airway intubation and resuscitation
Events that must be prevented by routine antiepileptic premedication for all patients
Permanently damaging to brain tissue requiring post-treatment neurological evaluation
Self-limiting events that resolve when oxygen exposure is reduced (Correct answer)

Correct answer: Self-limiting events that resolve when oxygen exposure is reduced

HBO-induced oxygen toxicity seizures are typically self-limiting and cease when the oxygen partial pressure is reduced; they rarely cause permanent neurological injury.

Question 57: Which of the following patients would be at GREATEST risk for CNS oxygen toxicity during an HBO session?

A patient who received a normal saline IV bolus prior to treatment
A patient with a fever of 102°F (38.9°C) and elevated metabolic rate (Correct answer)
A well-hydrated patient with well-controlled hypertension
An elderly patient with stable osteoarthritis on NSAIDs

Correct answer: A patient with a fever of 102°F (38.9°C) and elevated metabolic rate

Fever increases metabolic rate and lowers the seizure threshold, significantly increasing the risk of CNS oxygen toxicity during HBO therapy.

Question 58: A fire is detected inside a multiplace hyperbaric chamber. After activating the fire suppression system, what is the next priority?

Seal all vents to prevent oxygen from feeding the fire
Begin controlled emergency decompression following established protocols (Correct answer)
Immediately bring the chamber to surface pressure as fast as possible
Continue treatment and monitor the fire

Correct answer: Begin controlled emergency decompression following established protocols

After activating fire suppression, controlled emergency decompression following established protocols balances patient safety with decompression sickness risk.

Question 59: What is the primary mechanism by which central nervous system (CNS) oxygen toxicity occurs during hyperbaric oxygen therapy?

Decreased cerebral blood flow from vasoconstriction
Nitrogen narcosis interfering with neurotransmission
Hypercapnia from CO2 retention at elevated pressures
Formation of reactive oxygen species causing neuronal damage (Correct answer)

Correct answer: Formation of reactive oxygen species causing neuronal damage

CNS oxygen toxicity is primarily caused by reactive oxygen species (free radicals) that overwhelm antioxidant defenses and damage neuronal membranes.

Question 60: The lymphatic system returns interstitial fluid to the bloodstream and plays a role in wound healing relevant to HBOT. Lymph ultimately drains into venous circulation primarily via which structure?

Thoracic duct emptying into the left subclavian vein (Correct answer)
Hepatic portal system
Superior vena cava directly
Right atrium via coronary sinus

Correct answer: Thoracic duct emptying into the left subclavian vein

The thoracic duct, the largest lymphatic vessel, drains most of the body's lymph into the venous system at the junction of the left subclavian and internal jugular veins.

Question 61: Which of the following is the MOST appropriate method for passing medication into a hyperbaric chamber during treatment?

Throw the medication through the open entry port between pressurizations
Wait until decompression is complete to administer any medication
Dissolve medication in the chamber humidification system
Use the designated chamber medical pass-through port with appropriate pressure equalization (Correct answer)

Correct answer: Use the designated chamber medical pass-through port with appropriate pressure equalization

Medical pass-through ports are designed to safely transfer medications and supplies into pressurized chambers without interrupting treatment.

Question 62: HBOT enhances antibiotic efficacy in infected hypoxic wounds primarily because:

Elevated tissue PO2 restores neutrophil oxidative (respiratory burst) bactericidal activity (Correct answer)
Pressure physically forces antibiotic molecules deeper into tissue
High oxygen concentration chemically dissolves the antibiotic for better absorption
HBOT slows antibiotic metabolism, extending its duration of action

Correct answer: Elevated tissue PO2 restores neutrophil oxidative (respiratory burst) bactericidal activity

Neutrophil oxidative killing requires adequate tissue oxygen; in hypoxic infected wounds, HBOT restores PO2, enabling effective immune-mediated bacterial destruction alongside antibiotics.

Question 63: Which of the following best describes the mechanism by which HBO reduces intracranial pressure in carbon monoxide poisoning?

HBO chemically binds CO in the blood
HBO activates complement cascade to clear CO
HBO-induced vasoconstriction reduces cerebral edema (Correct answer)
HBO increases cerebral blood flow and oxygenation

Correct answer: HBO-induced vasoconstriction reduces cerebral edema

High PO2 causes cerebral vasoconstriction, reducing edema and ICP while still delivering adequate O2 via dissolved plasma oxygen.

Question 64: One atmosphere absolute (1 ATA) is equivalent to approximately:

33 psi
29.4 psi
7.35 psi
14.7 psi (Correct answer)

Correct answer: 14.7 psi

1 ATA equals approximately 14.7 psi (pounds per square inch), which is standard sea-level atmospheric pressure.

Question 65: Which anatomical consideration is most important when performing procedures near joints?

Only the skin surface appearance
Awareness of surrounding ligaments, tendons, and neurovascular structures (Correct answer)
The color of the tissue
Joint appearance from external observation only

Correct answer: Awareness of surrounding ligaments, tendons, and neurovascular structures

Awareness of ligaments, tendons, and neurovascular structures near joints is essential to prevent damage to these critical structures during procedures.

Question 66: Hyperbaric oxygen therapy enhances angiogenesis and collagen synthesis in chronic wounds. Which growth factor is primarily responsible for stimulating new capillary formation in HBOT-treated tissue?

Epidermal growth factor (EGF)
Platelet-derived growth factor (PDGF)
Transforming growth factor-alpha (TGF-α)
Vascular endothelial growth factor (VEGF) (Correct answer)

Correct answer: Vascular endothelial growth factor (VEGF)

HBOT upregulates VEGF expression in hypoxic wound edges, driving endothelial cell proliferation and new capillary sprouting (angiogenesis).

Question 67: A patient undergoing HBO therapy for carbon monoxide poisoning is unconscious. Who provides consent for continued treatment?

The next available physician who is not treating the patient
No consent is needed since the patient is already in the facility
The hyperbaric technician on duty
The patient's legally authorized representative or next of kin under implied consent doctrine (Correct answer)

Correct answer: The patient's legally authorized representative or next of kin under implied consent doctrine

When a patient cannot consent, the surrogate decision-maker or next of kin provides consent; in emergencies, implied consent allows treatment to save life.

Question 68: Which body system is most relevant to understanding tissue response to treatment?

The endocrine system exclusively
None, as anatomy is not relevant to treatment
The musculoskeletal and integumentary systems (Correct answer)
The reproductive system

Correct answer: The musculoskeletal and integumentary systems

The musculoskeletal and integumentary systems are most directly relevant as they comprise the tissues most commonly affected by and responsive to treatment interventions.

Question 69: A patient reports a recent upper respiratory infection with nasal congestion prior to their scheduled HBO session. The technician should be MOST concerned about:

Elevated blood glucose during treatment
Inability to equalize middle ear and sinus pressure during compression (Correct answer)
Higher likelihood of claustrophobia
Increased risk of oxygen toxicity seizure

Correct answer: Inability to equalize middle ear and sinus pressure during compression

Nasal congestion impairs Eustachian tube function, making it difficult or impossible to equalize middle ear pressure, increasing barotrauma risk.

Question 70: A patient reports significant sinus pain during compression that does not resolve with slow compression rate. What condition does this MOST likely represent?

Sinus squeeze (sinus barotrauma) (Correct answer)
CNS oxygen toxicity
Arterial gas embolism
Pulmonary overinflation

Correct answer: Sinus squeeze (sinus barotrauma)

Sinus squeeze occurs when blocked sinus ostia prevent equalization of pressure, causing mucosal hemorrhage and severe pain during compression.

Question 71: What is the usual pressure used in HBOT chambers?

4.5 ATA
2.5 ATA (Correct answer)
0.5 ATA
1.0 ATA

Correct answer: 2.5 ATA

The typical therapeutic pressure used in hyperbaric oxygen therapy (HBOT) chambers for most approved indications ranges from 2.0 to 3.0 atmospheres absolute (ATA). A pressure of 2.5 ATA is a common and effective setting that allows for significant increases in dissolved oxygen in the blood. This pressure optimizes therapeutic benefits while minimizing the risk of oxygen toxicity and barotrauma.

Question 72: Which condition requires a hyperbaric chamber to be taken out of service until inspected by a qualified engineer or inspector?

Discovery of a crack, weld defect, or visible deformation in the pressure hull (Correct answer)
An expired calibration certificate on a secondary monitoring gauge
A burned-out interior light bulb
Minor surface corrosion on exterior paint only

Correct answer: Discovery of a crack, weld defect, or visible deformation in the pressure hull

Any structural defect—cracks, weld flaws, or deformation—in the pressure boundary is a critical safety finding requiring engineering evaluation before further use.

Question 73: The sinoatrial (SA) node, the heart's primary pacemaker, is located in which cardiac chamber and supplied by which coronary artery in most individuals?

Right atrium; right coronary artery (Correct answer)
Interatrial septum; posterior descending artery
Left atrium; left circumflex artery
Right ventricle; left anterior descending artery

Correct answer: Right atrium; right coronary artery

The SA node lies in the superior right atrium near the SVC junction and is supplied by the SA nodal artery, a branch of the right coronary artery in ~60% of people.

Question 74: Pulmonary surfactant, which reduces alveolar surface tension and prevents collapse, is produced by which cell type?

Type II pneumocytes (Correct answer)
Type I pneumocytes
Clara cells
Alveolar macrophages

Correct answer: Type II pneumocytes

Type II pneumocytes synthesize and secrete surfactant (primarily dipalmitoylphosphatidylcholine), maintaining alveolar stability and preventing atelectasis.

Question 75: An HBO patient inside a monoplace chamber suddenly develops facial twitching and lip tremors. The technician's FIRST action should be:

Notify the physician and continue the treatment while observing closely
Switch the patient to air breathing and prepare to decompress the chamber (Correct answer)
Increase chamber pressure to suppress the developing seizure
Administer oxygen via non-rebreather mask through the side port

Correct answer: Switch the patient to air breathing and prepare to decompress the chamber

Facial twitching and lip tremors are VENTID-C warning signs of CNS oxygen toxicity; the immediate response is to remove the oxygen stimulus and begin safe decompression.

Question 76: During a hyperbaric oxygen treatment, a patient reports vision changes and facial twitching. What is the most likely cause and correct action?

Hypoglycemia; administer oral glucose
Ear squeeze; continue treatment and monitor
CNS oxygen toxicity; remove oxygen mask immediately (Correct answer)
Nitrogen narcosis; ascend to shallower depth

Correct answer: CNS oxygen toxicity; remove oxygen mask immediately

Facial twitching with vision changes are prodromal signs of CNS oxygen toxicity, requiring immediate removal of the oxygen mask and air break.

Question 77: Charles's Law describes the relationship between gas volume and:

Pressure at constant temperature
Molecular weight and diffusion rate
Solubility and partial pressure
Temperature at constant pressure (Correct answer)

Correct answer: Temperature at constant pressure

Charles's Law states that at constant pressure, the volume of a gas is directly proportional to its absolute temperature.

Question 78: According to CMS HBO coverage policy, which condition listed below is NOT a covered indication for hyperbaric oxygen therapy?

Acute stroke (Correct answer)
Diabetic lower extremity wounds (Wagner Grade II+)
Radiation tissue damage (osteoradionecrosis)
Chronic refractory osteomyelitis

Correct answer: Acute stroke

Acute stroke is not a CMS-covered indication for HBO therapy; coverage is limited to specific conditions listed in the LCD such as chronic osteomyelitis and radiation injury.

Question 79: When faced with a conflict of interest, what is the appropriate course of action?

Discuss it only if someone complains
Proceed as normal if it benefits the client
Disclose the conflict and recuse yourself from the situation (Correct answer)
Ignore the conflict if it seems minor

Correct answer: Disclose the conflict and recuse yourself from the situation

Disclosing conflicts of interest and recusing oneself ensures objective decision-making and maintains professional integrity.

Question 80: Which federal agency has primary jurisdiction over hyperbaric chambers classified as medical devices?

OSHA
FDA (Correct answer)
CMS
EPA

Correct answer: FDA

The FDA regulates hyperbaric oxygen chambers as Class II or Class III medical devices under the Federal Food, Drug, and Cosmetic Act.

Question 81: What is the purpose of moisture separators (water traps) installed in the compressed-air supply line to a hyperbaric chamber?

To lower supply line pressure before the primary regulator
To filter biological contaminants from ambient air
To reduce the oxygen concentration in the supply air
To remove condensed water that could corrode valves, degrade air quality, and damage regulators (Correct answer)

Correct answer: To remove condensed water that could corrode valves, degrade air quality, and damage regulators

Water traps prevent liquid water condensed during compression from entering and damaging downstream valves, gauges, and the chamber interior.

Question 82: When a patient experiences an oxygen toxicity seizure inside a monoplace chamber, the technician should:

Increase oxygen flow to maintain treatment pressure
Switch the patient to air, protect from injury, and prepare for emergency decompression if seizure persists (Correct answer)
Immediately decompress at maximum rate
Open the chamber immediately to provide airway support

Correct answer: Switch the patient to air, protect from injury, and prepare for emergency decompression if seizure persists

Switching to air terminates oxygen exposure, protecting the patient from further CNS injury while the seizure is managed safely inside the chamber.

Question 83: Why is it important to monitor pressure levels in a hyperbaric chamber?

To prevent chamber overheating.
To make sessions shorter.
To ensure correct therapeutic exposure and avoid barotrauma (Correct answer)
To reduce electricity usage.

Correct answer: To ensure correct therapeutic exposure and avoid barotrauma

Monitoring pressure levels in a hyperbaric chamber is critical for two main reasons: ensuring the patient receives the prescribed therapeutic dose of oxygen and preventing barotrauma. Maintaining the correct pressure ensures optimal oxygen delivery to tissues, while careful pressure control during compression and decompression prevents injury to air-filled body cavities like the ears and sinuses. This ensures both efficacy and safety of the treatment.

Question 84: Decompression sickness (DCS) Type II (neurological) most commonly affects which region of the spinal cord, producing classic lower-extremity symptoms?

Cervical cord anterior horn
Lumbar cord dorsal horn
Thoracic cord white matter (Correct answer)
Sacral cord parasympathetic neurons

Correct answer: Thoracic cord white matter

Bubble formation preferentially occurs in the thoracic spinal cord white matter due to its lipid-rich myelin content and relatively poor blood supply, causing paraplegia/paresthesia.

Question 85: Which gas law is most directly applied when calculating the total pressure of a gas mixture in a hyperbaric chamber?

Boyle's Law
Charles's Law
Graham's Law
Dalton's Law of Partial Pressures (Correct answer)

Correct answer: Dalton's Law of Partial Pressures

Dalton's Law states total pressure equals the sum of individual partial pressures of all gases in the mixture.

Question 86: The blood-brain barrier is primarily formed by which cell type surrounding cerebral capillaries?

Schwann cells
Microglia
Astrocytes (Correct answer)
Oligodendrocytes

Correct answer: Astrocytes

Astrocyte end-feet wrap around cerebral capillaries and contribute to tight junction formation, creating the blood-brain barrier.

Question 87: What is the primary purpose of documenting the exact time a hyperbaric treatment begins and ends?

To satisfy the patient's curiosity
For scheduling future appointments
To verify actual treatment duration for billing accuracy, clinical compliance, and regulatory requirements (Correct answer)
To calculate staff overtime

Correct answer: To verify actual treatment duration for billing accuracy, clinical compliance, and regulatory requirements

Exact treatment times are required to verify that the prescribed duration was delivered, ensure accurate billing, and demonstrate regulatory compliance.

Question 88: Which of the following medications taken by a patient MOST increases the risk of oxygen-induced seizure during HBO therapy?

Disulfiram (Antabuse) (Correct answer)
Omeprazole
Atorvastatin
Metformin

Correct answer: Disulfiram (Antabuse)

Disulfiram lowers the seizure threshold and significantly increases the risk of central nervous system oxygen toxicity during HBO treatment.

Question 89: Which of the following patients would require the MOST careful monitoring for pulmonary oxygen toxicity during a prolonged HBO treatment course?

A 60-year-old receiving daily HBO for 60 consecutive days for radiation tissue damage (Correct answer)
A 30-year-old diver with decompression sickness receiving a single Table 6 treatment
A 45-year-old with a healing diabetic foot ulcer receiving 20 treatments
A 55-year-old with carbon monoxide poisoning receiving three treatments

Correct answer: A 60-year-old receiving daily HBO for 60 consecutive days for radiation tissue damage

Pulmonary oxygen toxicity (Lorraine Smith effect) is associated with cumulative oxygen exposure; patients receiving many consecutive treatments are at highest risk.

Question 90: Which vital sign change would be EXPECTED as a normal physiologic response to hyperbaric oxygenation at therapeutic pressures?

Widened pulse pressure
Elevated respiratory rate due to increased oxygen demand
Mild bradycardia and slight decrease in cardiac output (Correct answer)
Increased heart rate and blood pressure

Correct answer: Mild bradycardia and slight decrease in cardiac output

HBO causes mild bradycardia and reduced cardiac output due to oxygen-induced peripheral vasoconstriction, which is a normal physiologic response.

Question 91: Which document provides the authority for hyperbaric technicians to perform procedures within their scope in most US states?

State-specific scope of practice laws and facility policies (Correct answer)
CHT credential alone
NFPA 99 certificate
UHMS membership card

Correct answer: State-specific scope of practice laws and facility policies

Scope of practice for hyperbaric technicians is defined by state law and individual facility credentialing policies, not by certification alone.

Question 92: Which chemotherapeutic agent is considered a major contraindication to HBO therapy due to significantly increased pulmonary toxicity risk?

Doxorubicin (Adriamycin)
Bleomycin (Correct answer)
Methotrexate
Cisplatin

Correct answer: Bleomycin

Bleomycin causes pulmonary fibrosis on its own, and HBO therapy dramatically potentiates this pulmonary toxicity, making concurrent use a major contraindication.

Question 93: Which of the following is the hallmark presentation of CNS oxygen toxicity during HBO therapy?

Grand mal (tonic-clonic) convulsions (Correct answer)
Gradual onset of confusion and disorientation
Sudden loss of consciousness without any warning signs
Progressive ascending peripheral numbness and tingling

Correct answer: Grand mal (tonic-clonic) convulsions

Grand mal convulsions are the hallmark of CNS oxygen toxicity; though they may be preceded by VENTID-C warning signs, they can also occur without warning.

Question 94: Transcutaneous oxygen measurement (TcPO2) is performed before HBO treatment primarily to:

Assess tissue perfusion and predict HBO therapy benefit for wound healing (Correct answer)
Monitor for oxygen toxicity risk
Determine the patient's pulmonary function
Establish baseline CO2 levels

Correct answer: Assess tissue perfusion and predict HBO therapy benefit for wound healing

TcPO2 measures tissue oxygenation at the wound site; values below 40 mmHg (breathing air) and rising to >200 mmHg with O2 predict positive HBO response.

Question 95: Why is continuing education important for maintaining ethical practice?

It is optional for experienced practitioners
It is only needed to maintain certification status
It ensures practitioners stay current with evolving standards and best practices (Correct answer)
It replaces the need for experience

Correct answer: It ensures practitioners stay current with evolving standards and best practices

Continuing education ensures practitioners stay current with evolving standards, new research, and best practices, directly supporting ethical and competent practice.

Question 96: At 3 ATA breathing air (21% O2, 79% N2), the partial pressure of nitrogen is approximately:

2280 mmHg
1520 mmHg
760 mmHg
1800 mmHg (Correct answer)

Correct answer: 1800 mmHg

At 3 ATA, total pressure = 3 × 760 = 2280 mmHg; nitrogen partial pressure = 0.79 × 2280 ≈ 1800 mmHg.

Question 97: During patient assessment, you note a Braden Scale score of 12. This indicates the patient is at:

Low risk for pressure ulcer development
Moderate risk for pressure ulcer development
No risk for pressure ulcer development
High risk for pressure ulcer development (Correct answer)

Correct answer: High risk for pressure ulcer development

A Braden Scale score of 12 falls in the high-risk range (≤12), indicating significant susceptibility to pressure injuries relevant to wound care patients.

Question 98: A hyperbaric patient with a history of seizures is being considered for HBO therapy. Which precaution is MOST appropriate?

Limit sessions to 30 minutes regardless of the prescribed protocol
Ensure seizure medications are taken, keep a lower treatment pressure if possible, and have seizure management equipment ready (Correct answer)
Seizure history is an absolute contraindication; cancel all HBO treatments
Administer prophylactic oxygen at atmospheric pressure before the session

Correct answer: Ensure seizure medications are taken, keep a lower treatment pressure if possible, and have seizure management equipment ready

A history of seizures is a relative contraindication; risk is managed by ensuring medication compliance, using lower pressures when feasible, and having emergency equipment available.

Question 99: Fick's Law of Diffusion states that the rate of diffusion increases with:

Increasing surface area and concentration gradient (Correct answer)
Decreasing concentration gradient
Decreasing molecular weight only
Increasing membrane thickness

Correct answer: Increasing surface area and concentration gradient

Fick's Law states diffusion rate is proportional to surface area and concentration gradient, and inversely proportional to membrane thickness.

Question 100: Which of the following is an example of objective data that should be documented in a hyperbaric treatment record?

Patient states 'I feel better today'
Patient appears anxious
Wound looks improved
Blood pressure reading of 138/86 mmHg (Correct answer)

Correct answer: Blood pressure reading of 138/86 mmHg

Objective data consists of measurable, quantifiable findings such as numerical vital sign values that can be verified by another observer.

Certified Hyperbaric Technologist (CHT) Exam

Certifies individuals in the safe and effective operation of hyperbaric chambers and the care of patients undergoing hyperbaric oxygen therapy.

100

Questions

120 min

Time Limit

70%

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