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Question 1. Which component of a hyperbaric chamber prevents fire by limiting the oxygen concentration to below 25 %? A) Carbon dioxide scrubber B) Oxygen overboard discharge system C) Fire suppression system D) Atmospheric control valve Answer: B Explanation: The oxygen overboard discharge system vents excess O₂, keeping chamber O₂ levels below the 25 % threshold that significantly reduces fire risk. Question 2. In the chamber’s structural integrity hierarchy, which lock provides the primary barrier against pressure loss when the medical lock is opened? A) Inner lock B) Outer lock C) Medical lock D) Supply lock Answer: A Explanation: The inner lock is the first line of containment; opening the medical lock does not compromise the inner lock’s seal, preserving chamber pressure. Question 3. What is the primary purpose of the CO₂ scrubber in a hyperbaric chamber? A) Increase oxygen partial pressure B) Remove carbon dioxide from the breathing loop C) Provide fire suppression D) Regulate chamber temperature Answer: B Explanation: CO₂ scrubbers chemically absorb carbon dioxide from exhaled gas, preventing toxic buildup and maintaining a safe breathing environment.
Question 4. During pressurization, a patient complains of “ear squeezes.” Which physiological event is most likely occurring? A) Middle‑ear pressure equalization failure B) Carbon dioxide toxicity C] Nitrogen narcosis D) Oxygen toxicity seizure Answer: A Explanation: Ear squeezes result from an inability to equalize middle‑ear pressure with the increasing ambient pressure, causing pain and possible barotrauma. Question 5. Which of the following is NOT a standard step in a field neurological assessment for DCS? A) Testing cranial nerves B) Evaluating motor strength C) Measuring arterial blood gases D) Assessing coordination Answer: C Explanation: While arterial blood gases are important, they are not part of the rapid bedside neuro exam; the exam focuses on cranial nerves, motor, sensory, and coordination. Question 6. In Treatment Table 5, what is the prescribed depth? A) 30 fsw B) 45 fsw C) 60 fsw D) 90 fsw Answer: C Explanation: Table 5 is a 60 fsw treatment table used for moderate decompression sickness with specific oxygen breathing cycles. Question 7. A diver presents with rapid onset of neurological deficits and loss of consciousness after surfacing. Which condition is most consistent with this presentation?
B) Open outer lock, start oxygen overboard, check depth gauges C) Test communication, set ventilation rate, pressurize immediately D) Load patients, start CO₂ scrubbers, ignore fire suppression Answer: A Explanation: Safety requires confirming fire suppression, ensuring air banks are charged, and verifying CO₂ scrubbers before pressurizing. Question 11. How is the ventilation rate calculated for a chamber occupied by three divers breathing through demand‑type masks? A) 5 L/min per person B) 10 L/min per person C) 15 L/min per person D) 20 L/min per person Answer: B Explanation: Demand‑type masks typically require about 10 L/min of fresh gas per occupant to prevent CO₂ accumulation. Question 12. Which valve reduces chamber pressure to a safe level for external access? A) Manifold valve B) Pressure‑reducing valve C) Exhaust valve D) Supply valve Answer: B Explanation: The pressure‑reducing valve allows controlled depressurization, protecting personnel and equipment during entry/exit. Question 13. During a Table 6A treatment, a patient’s symptoms worsen at 30 fsw. What is the recommended immediate action? A) Continue the same table unchanged B) Switch to Table 7 without changing depth
C) Extend the O₂ breathing period and consider table upgrade D) Abort treatment and surface the patient Answer: C Explanation: Table 6A allows extensions of O₂ periods based on patient response; worsening symptoms merit a longer O₂ phase and possible upgrade. Question 14. Which of the following items is prohibited inside the chamber lock due to fire risk? A) Saline IV bag B) Battery‑powered flashlight C) Sterile gauze D) Plastic water bottle Answer: B Explanation: Battery‑powered devices can generate heat or sparks, making them “hot” items that are forbidden in the oxygen‑rich environment. Question 15. What is the primary hazard associated with “Tender Squeeze” during rapid pressurization? A) Nitrogen narcosis in the tender B) Barotrauma to the tender’s ears and sinuses C) Hyperventilation of the tender D] Oxygen toxicity seizure in the tender Answer: B Explanation: Tender squeeze refers to the rapid pressure change experienced by the tender, potentially causing ear and sinus barotrauma. Question 16. In the context of hyperbaric treatment, what does “Time of Relief” refer to? A) The moment the patient is removed from the chamber B) The instant the first symptom improves after oxygen breathing C) The time when the chamber reaches target depth D) The duration of the entire treatment session
Question 20. What is the recommended maximum O₂ concentration inside a hyperbaric chamber to minimize fire risk? A) 15 % B) 21 % C) 25 % D) 30 % Answer: C Explanation: Keeping O₂ below 25 % reduces the likelihood of combustion in the enriched‑oxygen environment. Question 21. Which symptom distinguishes Type II DCS from Type I DCS? A) Skin itching B) Joint pain C) Neurological deficits D) Ear barotrauma Answer: C Explanation: Type II DCS involves serious neurological or cardiopulmonary manifestations, whereas Type I is limited to musculoskeletal pain. Question 22. During a pressurization descent, a diver reports a “sinus block.” What immediate measure should be taken? A) Increase the rate of descent B) Administer a decongestant and pause descent C) Switch to 100 % oxygen breathing D) Decompress the chamber immediately Answer: B Explanation: Treating the sinus blockage with a decongestant and pausing allows pressure equalization, preventing barotrauma.
Question 23. Which of the following is the correct order for lock‑in/lock‑out procedures when passing an IV bag through the medical lock? A) Open outer lock → open inner lock → insert bag → close inner lock → close outer lock B) Open inner lock → open outer lock → insert bag → close outer lock → close inner lock C) Open outer lock → depressurize → insert bag → repressurize → close outer lock D) Open inner lock → depressurize → insert bag → repressurize → close inner lock Answer: A Explanation: The outer lock is opened first to maintain chamber pressure, then the inner lock, allowing the bag to pass without pressure loss. Question 24. In Table 7, what is the primary reason for its “saturation‑like” profile? A) It treats only superficial DCS symptoms B) It involves prolonged exposure at depth with repeated O₂ cycles C) It uses only air breathing throughout the treatment D) It requires immediate surface decompression after the first O₂ period Answer: B Explanation: Table 7’s design includes extended depth exposure and multiple O₂ breathing phases, mimicking saturation treatment characteristics. Question 25. Which gas is primarily removed by the chamber’s CO₂ scrubber? A) Nitrogen B) Helium C) Carbon dioxide D) Oxygen Answer: C Explanation: The scrubber’s purpose is to chemically absorb carbon dioxide, preventing toxic accumulation. Question 26. What is the purpose of the “manual tapper” system? A) To control chamber pressure automatically
C) O₂ supply manifold D) Atmospheric control valve Answer: C Explanation: The O₂ supply manifold delivers medical‑grade oxygen to the breathing circuit. Question 30. Which of the following actions is required before opening the outer lock for a tender to enter the chamber? A) Verify chamber pressure is at atmospheric (0 fsw) B) Ensure the inner lock is sealed and pressurized C) Increase O₂ concentration to 30 % D) Turn off the CO₂ scrubber Answer: B Explanation: The inner lock must remain sealed to maintain pressure integrity while the outer lock is opened for tender access. Question 31. What is the primary purpose of the internal fire hose or water deluge system? A) To cool the chamber during pressurization B) To extinguish fires that may ignite inside the chamber C) To vent excess CO₂ D) To provide a source of fresh water for patients Answer: B Explanation: The fire hose/deluge system is installed for rapid fire suppression within the oxygen‑rich environment. Question 32. Which of the following is a characteristic sign of an oxygen‑toxicity seizure? A) Bilateral calf clonus B) Visual disturbances (blurred vision) C) Generalized tonic‑clonic activity without prior warning signs D) Persistent ear pain Answer: C
Explanation: High‑partial‑pressure O₂ can precipitate a generalized seizure, often without preceding minor symptoms. Question 33. During a Table 4 treatment, the patient experiences a sudden loss of motor function. What is the most appropriate immediate response? A) Continue the current O₂ schedule B) Switch to Table 6A and increase O₂ depth C) Administer 100 % O₂ at the current depth and consider table upgrade D) Rapidly decompress to surface Answer: C Explanation: Immediate 100 % O₂ at the current depth is critical; if neurological signs persist, upgrading the treatment table is warranted. Question 34. Which parameter is NOT typically recorded in the hyperbaric chamber log? A) Depth changes with timestamps B) Gas mixture switches C) Patient’s blood glucose level D) Medical observations Answer: C Explanation: Blood glucose is not a standard entry in the chamber log unless specifically required for a diabetic patient; depth, gas, and observations are mandatory. Question 35. What is the consequence of exceeding the recommended O₂ concentration (>25 %) inside the chamber? A) Increased risk of nitrogen narcosis B) Higher probability of fire ignition C) Reduced effectiveness of CO₂ scrubbers D) Immediate decompression sickness Answer: B Explanation: Elevated O₂ levels raise the flammability of materials, dramatically increasing fire risk.
Question 39. When a patient is breathing through a full‑face mask, what is the approximate minimum fresh gas flow required to avoid CO₂ buildup? A) 5 L/min B) 10 L/min C) 15 L/min D) 20 L/min Answer: B Explanation: Full‑face masks generally need about 10 L/min of fresh gas to keep CO₂ concentrations below toxic levels. Question 40. Which lock must be opened first to allow a medical supply to be passed into the chamber without losing pressure? A) Inner lock B) Outer lock C) Medical lock D) Supply lock Answer: B Explanation: Opening the outer lock first preserves the pressure seal of the inner lock while granting access to the medical lock. Question 41. During a Table 8 treatment, a patient’s skin shows mottling and itching. What is the most likely diagnosis? A) Type I DCS (skin bends) B) Oxygen toxicity rash C) AGE skin manifestation D) Nitrogen narcosis Answer: A Explanation: Mottling and itching are classic cutaneous signs of Type I DCS, often termed “skin bends.” Question 42. Which of the following is a primary function of the manifold in a hyperbaric chamber system?
A) To regulate CO₂ scrubber temperature B) To distribute breathing gases to multiple outlets simultaneously C) To measure chamber depth D) To control the fire suppression system Answer: B Explanation: The manifold distributes supplied gases (air, O₂) to all breathing circuits within the chamber. Question 43. What is the recommended action if a patient experiences a convulsion inside the chamber? A) Increase chamber pressure by 5 fsw B) Immediately discontinue O₂ breathing C) Administer 100 % O₂ and follow seizure protocol, then consider table upgrade D) Depressurize to surface within 5 minutes Answer: C Explanation: High‑flow 100 % O₂ is the first step to mitigate oxygen toxicity and support cerebral metabolism; seizure protocol and possible table upgrade follow. Question 44. Which depth gauge reading indicates a chamber pressure of 60 fsw? A) 2 atm B) 3 atm C) 4 atm D) 5 atm Answer: C Explanation: Each 33 fsw equals approximately 1 atm; 60 fsw ≈ 2 atm gauge + 1 atm atmospheric = 3 atm absolute, but depth gauges typically read gauge pressure; thus 60 fsw corresponds to 2 atm gauge, which is indicated as “4 atm absolute” on many gauges. The correct answer reflecting gauge reading is C (4 atm absolute). Question 45. Which of the following best describes a “blown” decompression? A) A planned rapid ascent after a dive
B) The outer lock isolates the chamber from the external environment, the inner lock isolates the medical lock. C) Both locks provide identical isolation; they are redundant. D) Neither lock provides pressure isolation; they only control access. Answer: B Explanation: The outer lock separates the chamber interior from the outside, while the inner lock isolates the medical lock area. Question 49. In the context of hyperbaric medicine, what does “saturation‑like” refer to? A) A treatment that mimics the physiological conditions of saturation diving, with prolonged exposure at depth. B) A rapid decompression protocol. C) A method of saturating the breathing gas with helium. D) A fire‑safety procedure. Answer: A Explanation: “Saturation‑like” treatments involve extended depth exposure, similar to actual saturation diving profiles. Question 50. Which of the following items can be safely passed through the medical lock without pressure loss? A) Open‑air water bottle B) Capped IV bag vented to ambient pressure C) Unsealed medication vial D) Electronic device with battery Answer: B Explanation: A capped IV bag vented to ambient pressure equalizes internal pressure, preventing pressure loss when transferred. Question 51. What is the purpose of recording “Time of Relief” and “Time of Change” during treatment? A) To calculate total treatment duration only
B) To document the exact moments of symptom improvement or deterioration for clinical assessment C) To synchronize chamber clocks with surface time D) To determine the amount of O₂ used Answer: B Explanation: These timestamps provide objective data on patient response, guiding treatment adjustments. Question 52. Which depth is associated with the onset of “rapture of the deep” (severe nitrogen narcosis) in most divers? A) 30 fsw B) 60 fsw C) 100 fsw D) 165 fsw Answer: D Explanation: Severe nitrogen narcosis typically manifests beyond 150 fsw, with 165 fsw often cited as a threshold for “rapture of the deep.” Question 53. If a chamber’s CO₂ scrubber fails during treatment, what is the maximum safe duration before initiating emergency decompression? A) 5 minutes B) 10 minutes C) 15 minutes D) 30 minutes Answer: B Explanation: CO₂ levels can become hazardous within 10 minutes of scrubber failure, necessitating rapid response. Question 54. Which of the following is NOT a function of the pressure‑reducing valve? A) Controlled chamber depressurization B) Maintaining safe pressure for external equipment connections
D) To improve patient comfort Answer: B Explanation: Lowering O₂ concentration minimizes the flammability of materials inside the oxygen‑rich environment. Question 58. Which of the following is a sign of a developing ear squeeze during pressurization? A) Sudden loss of vision B) Ear pain that worsens with pressure increase C) Tingling in the fingertips D) Shortness of breath Answer: B Explanation: Ear pain that intensifies as pressure rises indicates an inability to equalize middle‑ear pressure. Question 59. In hyperbaric treatment, what does “extending the O₂ period” mean? A) Adding extra minutes of 100 % O₂ breathing beyond the scheduled time B) Switching to a higher oxygen concentration (>100 %) C) Reducing the depth while continuing O₂ breathing D) Replacing O₂ with air for a short interval Answer: A Explanation: Extension adds additional O₂ breathing time to improve symptom resolution. Question 60. Which of the following best describes the “primary intercom” function? A) To control chamber pressure automatically B) To provide voice communication between inside and outside personnel under normal conditions C) To vent excess CO₂ from the chamber D) To monitor patient vitals remotely Answer: B Explanation: The primary intercom is the main electronic voice communication system used during normal operations.
Question 61. When a patient’s neurological exam shows cranial nerve III palsy, which symptom is most likely observed? A) Loss of smell B) Double vision (diplopia) and ptosis C) Decreased hearing acuity D) Loss of sensation on the face Answer: B Explanation: Cranial nerve III (oculomotor) palsy manifests as ptosis and diplopia due to impaired eye movement. Question 62. Which of the following is a required step before initiating a Table 5 treatment? A) Verify that the chamber is at atmospheric pressure B) Ensure the patient is breathing 100 % O₂ for at least 30 minutes prior C) Conduct a full pre‑operational checklist including fire suppression verification D) Reduce chamber temperature to below 20 °C Answer: C Explanation: A complete pre‑operational checklist is mandatory before any treatment table is started. Question 63. What is the effect of a “medical lock transfer” on chamber pressure? A) It causes a rapid pressure drop equal to the volume of the lock B) It maintains pressure if performed correctly using lock‑in/lock‑out technique C) It increases chamber pressure by 1 atm D) It vents CO₂ from the chamber Answer: B Explanation: Proper lock‑in/lock‑out procedures allow items to be transferred without compromising chamber pressure. Question 64. Which symptom is most indicative of a severe oxygen toxicity seizure? A) Mild headache
