Medical Gas Therapy
Expert-defined terms from the Certificate in Hyperbaric Medicine (United Kingdom) course at LearnUNI. Free to read, free to share, paired with a professional course.
Acetylene – A combustible gas occasionally encountered in industrial sett… #
Related terms: flammable gases, safety protocols The presence of acetylene in a chamber can cause fire hazards; therefore, strict cleaning and monitoring procedures are required.
Air – The natural mixture of gases (≈78% nitrogen, 21% oxygen) that serve… #
Related terms: ambient air, fractional inspired oxygen (FiO₂) In hyperbaric medicine, air may be used as a control gas during research protocols to compare outcomes against enriched oxygen environments.
Alveolar Gas Equation – A formula that calculates the partial pressure of… #
Related terms: PAO₂, PaO₂, FiO₂ Understanding this equation helps clinicians predict oxygenation improvements during hyperbaric treatment and adjust prescriptions accordingly.
Atmospheric Pressure – The pressure exerted by the weight of the atmosphe… #
3 kPa (1 ATA). Related terms: absolute pressure, gauge pressure Hyperbaric chambers are calibrated in multiples of atmospheric pressure; for example, 2 ATA equals twice the sea‑level pressure.
Barotrauma – Tissue injury caused by rapid changes in pressure, commonly… #
Related terms: middle‑ear squeeze, pulmonary barotrauma Proper equalisation techniques and patient screening are essential to minimise barotrauma risk during compression and decompression phases.
Barometric Chamber – A sealed enclosure capable of altering internal pres… #
Related terms: monoplace chamber, multiplace chamber Chambers can be classified by size and design, influencing patient capacity, gas delivery systems, and safety features.
Boyle’s Law – The principle that, at constant temperature, the volume of… #
Related terms: gas laws, Charles’s law This law explains why gas‑filled cavities (e.g., middle ear) expand or contract during pressure changes, guiding equalisation strategies.
Carbon Dioxide (CO₂) – A colourless gas produced by cellular metabolism;… #
Related terms: hypercapnia, CO₂ retention Elevated CO₂ levels can stimulate breathing, but excessive accumulation may lead to respiratory acidosis, requiring careful monitoring.
Carbon Monoxide (CO) – A toxic gas formed by incomplete combustion; expos… #
Related terms: CO poisoning, carboxyhemoglobin Hyperbaric oxygen therapy is a definitive treatment for CO poisoning, accelerating the dissociation of CO from haemoglobin.
Closed‑Circuit Rebreather – A respiratory system that recirculates exhale… #
Related terms: open‑circuit system, CO₂ scrubber In multiplace chambers, closed‑circuit systems allow precise control of FiO₂ and reduce waste gas, enhancing cost‑effectiveness.
Compression Phase – The period during which chamber pressure is increased… #
Related terms: ramp rate, compression schedule A controlled compression rate (typically 1 ATA per minute) reduces discomfort and mitigates barotrauma risk.
Decompression Phase – The gradual reduction of chamber pressure back to a… #
Related terms: decompression schedule, stop Proper decompression is critical to avoid decompression sickness, especially in patients with underlying pulmonary pathology.
Decompression Sickness (DCS) – A condition caused by inert gas bubbles fo… #
Related terms: “the bends”, arterial gas embolism Although rare in therapeutic hyperbaric settings, vigilance is required for patients with recent scuba exposure or air‑containing wounds.
Diffusion Gradient – The difference in partial pressure of a gas between… #
Related terms: Fick’s law, oxygen diffusion Hyperbaric oxygen therapy increases the diffusion gradient for oxygen, facilitating delivery to hypoxic tissues.
Double‑Wall Chamber – A hyperbaric enclosure consisting of an inner press… #
Related terms: single‑wall chamber, composite chamber Double‑wall designs enhance safety by providing a secondary barrier against leaks and structural failure.
Duration of Exposure – The total time a patient spends at the therapeutic… #
Related terms: treatment run time, total session time Standard protocols range from 60 to 120 minutes, with adjustments based on indication and patient tolerance.
Effective Oxygen Delivery (EOD) – The quantity of oxygen that reaches via… #
Related terms: tissue oxygen tension, oxygen utilisation EOD is a key metric for evaluating treatment efficacy in conditions such as chronic wounds or ischemic injuries.
Enriched Air Nitrox (EAN) – A breathing gas mixture containing a higher p… #
Related terms: trimix, diving gases EAN is occasionally employed in hyperbaric therapy to achieve moderate oxygen enrichment while limiting fire risk.
Equilibration – The process by which gas concentrations become uniform th… #
Related terms: steady state, gas exchange During hyperbaric exposure, equilibration of oxygen occurs within minutes, allowing rapid therapeutic effects.
Exhalation Valve – A device that permits controlled release of exhaled ga… #
Related terms: pressure regulator, venturi Proper valve function prevents over‑pressurisation and contributes to patient comfort.
Fractional Inspired Oxygen (FiO₂) – The proportion of oxygen in the gas m… #
Related terms: oxygen concentration, oxygen fraction FiO₂ can be adjusted from 0.21 (ambient air) up to 1.0 (100% oxygen) depending on therapeutic goals.
Gas‑Filled Cavity – Any anatomical space containing gas, such as the midd… #
Related terms: pneumatic cavity, barometric compliance These cavities must be equalised before and during hyperbaric exposure to avoid pressure‑related injury.
Hyperbaric Oxygen Therapy (HBOT) – The clinical use of 100% oxygen at pre… #
Related terms: monoplace HBOT, multiplace HBOT Indications include decompression illness, carbon‑monoxide poisoning, chronic refractory wounds, and certain infections.
Hypercapnia – Elevated arterial CO₂ levels, often resulting from hypovent… #
Related terms: respiratory acidosis, CO₂ retention In hyperbaric settings, hypercapnia can be induced intentionally to stimulate ventilation, but must be monitored to avoid adverse effects.
Hypobaric Therapy – The deliberate reduction of ambient pressure to treat… #
Related terms: altitude training, hypobaric chamber While not a primary focus of the Certificate in Hyperbaric Medicine, understanding hypobaric principles aids comprehensive training.
Inert Gas – A gas that does not readily react chemically under physiologi… #
Related terms: nitrogen narcosis, inert gas loading In hyperbaric therapy, inert gases are reduced to minimise bubble formation and optimise oxygen delivery.
Isobaric Oxygen – Administration of oxygen at ambient pressure without in… #
Related terms: normobaric oxygen therapy, high‑flow nasal cannula Isobaric oxygen may be used as an adjunct or alternative when hyperbaric treatment is contraindicated.
Jugular Venous Oxygen Saturation (SjvO₂) – A measurement of oxygen satura… #
Related terms: cerebral oximetry, brain tissue oxygenation SjvO₂ monitoring can provide insight into the adequacy of cerebral oxygenation during HBOT.
Laser #
Assisted Wound Healing – A technique that uses low‑level laser therapy to stimulate cellular repair; often combined with HBOT for synergistic effect. Related terms: photobiomodulation, adjunct therapy Clinical studies suggest enhanced granulation tissue formation when both modalities are applied sequentially.
Leak Test – A safety procedure to verify the integrity of a hyperbaric ch… #
Related terms: pressure testing, chamber certification Regular leak testing prevents uncontrolled depressurisation and ensures compliance with regulatory standards.
Monoplace Chamber – A single‑patient hyperbaric chamber typically constru… #
Related terms: multiplace chamber, single‑occupancy chamber Monoplace chambers are widely used for routine HBOT due to their simplicity and lower operating costs.
Multiplace Chamber – A larger chamber capable of treating multiple patien… #
Related terms: group HBOT, chamber capacity Multiplace chambers allow for complex treatment protocols, including those requiring concurrent medical monitoring.
Normobaric Oxygen Therapy (NBOT) – Delivery of oxygen at ambient pressure… #
Related terms: high‑flow oxygen, oxygen concentrator NBOT is less invasive but provides lower tissue oxygen tensions compared with HBOT, limiting its therapeutic range.
O₂ Toxicity – Cellular injury caused by excessive exposure to high partia… #
Related terms: pulmonary oxygen toxicity, CNS oxygen toxicity Treatment protocols limit exposure time and pressure to mitigate toxicity while achieving therapeutic benefit.
Oxygen Concentrator – A device that extracts and concentrates oxygen from… #
Related terms: medical grade oxygen, oxygen generator Concentrators are commonly used in NBOT settings and as backup sources for HBOT facilities.
Oxygen Cockpit – The internal environment of a hyperbaric chamber where o… #
Related terms: chamber atmosphere, oxygen monitoring Maintaining appropriate oxygen levels in the cockpit is critical to prevent fire hazards and ensure patient safety.
Oxygen Partial Pressure (pO₂) – The pressure exerted by oxygen within a g… #
Related terms: alveolar pO₂, arterial pO₂ In HBOT, pO₂ can exceed 2,000 mmHg, dramatically increasing dissolved oxygen in plasma.
Oxygen Toxicity Threshold – The maximum safe exposure duration at a given… #
Related terms: UPTD (units per tissue dose), OTU (oxygen toxicity units) Clinicians calculate cumulative exposure using OTU tables to stay within safe limits.
Oxygen Therapy – The administration of oxygen to patients to correct hypo… #
Related terms: supplemental oxygen, therapeutic oxygen HBOT represents a high‑pressure form of oxygen therapy, distinguished from conventional low‑pressure methods.
Oxygen Uptake Ratio (OUR) – The proportion of delivered oxygen that is ac… #
Related terms: oxygen consumption, VO₂ OUR helps assess the efficiency of hyperbaric treatments and may guide adjustments in pressure or duration.
Partial Pressure – The pressure contributed by an individual gas within a… #
Related terms: Dalton’s law, total pressure Understanding partial pressures is fundamental for calculating FiO₂ and predicting physiological responses.
Patient Monitoring – Continuous observation of vital signs, oxygen satura… #
Related terms: telemetry, bedside monitoring Effective monitoring enables early detection of adverse events such as barotrauma or oxygen toxicity.
Pressure Regulator – A device that controls the flow and pressure of gas… #
Related terms: flow controller, pressure relief valve Accurate regulation ensures the prescribed therapeutic pressure is maintained throughout the session.
Pressure‑Controlled Ventilation (PCV) – A mechanical ventilation mode whe… #
Related terms: volume‑controlled ventilation, mechanical ventilation PCV may be employed for patients requiring assisted breathing during hyperbaric treatment.
Pressure‑Relief Valve – A safety component that automatically releases ex… #
Related terms: safety valve, burst disc Regular testing of the valve is mandatory for compliance with UK hyperbaric safety standards.
Pulmonary Barotrauma (PBT) – Lung injury caused by over‑expansion of alve… #
Related terms: air embolism, lung over‑inflation Screening for pre‑existing lung disease and using appropriate compression rates reduces PBT incidence.
Radiation‑Induced Tissue Damage – Cellular injury resulting from ionising… #
Related terms: osteoradionecrosis, radiotherapy side effects HBOT promotes angiogenesis and fibroblast activity, improving healing in irradiated tissues.
Rebreather System – A closed‑circuit apparatus that recirculates exhaled… #
Related terms: scrubber, open‑circuit system In multiplace chambers, rebreathers allow precise FiO₂ control and reduce oxygen consumption.
Regulatory Compliance – Adherence to national and international standards… #
Related terms: certification, quality assurance Compliance ensures legal operation, patient safety, and eligibility for NHS reimbursement.
Respiratory Acidosis – A decrease in blood pH due to elevated CO₂ levels,… #
Related terms: hypercapnia, ventilation–perfusion mismatch During HBOT, careful monitoring of CO₂ is required to avoid exacerbating acidosis, especially in patients with compromised lung function.
Return‑to‑Service (RTS) Protocol – A structured plan for resuming normal… #
Related terms: post‑treatment assessment, clearance RTS protocols are essential for divers, pilots, and occupational groups exposed to pressure changes.
Safety Officer – The designated individual responsible for overseeing cha… #
Related terms: chamber supervisor, emergency coordinator The safety officer must hold appropriate training and certification, as mandated by UK regulations.
Sealed‑Valve System – A breathing apparatus where the valve closes on exh… #
Related terms: demand valve, non‑rebreather Sealed‑valve systems reduce oxygen wastage and are commonly used in monoplace chambers.
Seizure Risk – The potential for convulsive events during HBOT, particula… #
Related terms: CNS oxygen toxicity, prophylactic antiepileptic Protocols limit exposure to pressures above 3 ATA and include pre‑treatment neurological assessment.
Shallow Water Blackout – A loss of consciousness caused by rapid reductio… #
Related terms: hypoxic blackout, dive safety Education on this phenomenon is part of the broader hyperbaric safety curriculum.
Side‑Stream Monitoring – Sampling of gas from the breathing circuit to an… #
Related terms: gas analyser, capnography Side‑stream monitors provide immediate feedback, enabling rapid adjustments to maintain therapeutic targets.
Skin Graft Incorporation – The process by which a transplanted skin layer… #
Related terms: graft take, neovascularisation Adjunctive HBOT enhances graft survival by increasing oxygen delivery and stimulating angiogenesis.
Standard Operating Procedure (SOP) – A documented set of step‑by‑step ins… #
Related terms: protocol, workflow SOPs ensure consistency, safety, and compliance across all staff members.
Steam Sterilisation – A method of decontaminating equipment using saturat… #
Related terms: autoclave, aseptic processing Proper sterilisation prevents nosocomial infections, especially when treating immunocompromised patients.
Stenosis – Narrowing of a lumen, such as a blood vessel or airway, which… #
Related terms: vascular stenosis, airway obstruction HBOT may be employed to promote healing of post‑surgical stenoses by delivering high oxygen concentrations to the affected tissue.
Supplemental Oxygen – Additional oxygen provided beyond ambient levels, d… #
Related terms: oxygen therapy, high‑flow oxygen In HBOT, supplemental oxygen is 100% and administered at elevated pressures to achieve therapeutic plasma‑dissolved oxygen levels.
Surface Tension – The cohesive force at the interface between liquid and… #
Related terms: surfactant, alveolar collapse Hyperbaric pressure reduces surface tension effects, aiding in the recruitment of collapsed alveoli during treatment.
Sustained Release – A pharmacological concept where a drug is released gr… #
Related terms: drug delivery system, controlled release Research explores synergistic effects of sustained‑release antibiotics and hyperbaric oxygen in chronic infections.
Sympathetic Nervous System – Part of the autonomic nervous system that me… #
Related terms: parasympathetic system, autonomic regulation Hyperbaric exposure can modulate sympathetic activity, affecting blood pressure and heart rate during treatment.
Systemic Inflammatory Response Syndrome (SIRS) – A widespread inflammator… #
Related terms: sepsis, cytokine storm Monitoring inflammatory markers during HBOT helps differentiate therapeutic benefits from potential hyperoxic stress.
Thermal Conductivity – The ability of a material to transfer heat; releva… #
Related terms: insulation, heat loss Acrylic chambers have lower thermal conductivity than steel, reducing heat loss at higher pressures.
Thermal Stress – Physiological strain caused by temperature extremes; hyp… #
Related terms: heat dissipation, patient comfort Ventilation systems and cooling jackets are employed to mitigate thermal stress during long sessions.
Time‑Weighted Average (TWA) – A statistical measure of exposure to a gas… #
Related terms: exposure limit, TLV In hyperbaric facilities, TWA calculations ensure staff are not over‑exposed to elevated oxygen levels.
Totally‑Occluded Airway – A complete blockage of the airway, a contraindi… #
Related terms: airway obstruction, emergency airway Prior to HBOT, airway patency must be confirmed to prevent barotrauma from trapped gas.
Transcutaneous Oxygen Monitoring (TcPO₂) – Non‑invasive measurement of ox… #
Related terms: skin oximetry, peripheral oxygenation TcPO₂ values rise significantly during HBOT, providing objective data on treatment efficacy for chronic wounds.
Trapped Gas – Air or other gases confined within body cavities, such as s… #
Related terms: pneumatic cavity, barometric equilibration Prior to compression, clinicians must ensure adequate venting of trapped gas to avoid pressure‑related injury.
Turn‑Down Ratio – The proportion by which the pressure is reduced during… #
Related terms: decompression schedule, pressure gradient A typical turn‑down ratio of 1:1.5 to 1:2 balances treatment efficacy with safety.
Two‑Stage Compression – A compression protocol that involves an initial r… #
Related terms: ramp compression, staged compression This approach can improve patient tolerance while maintaining therapeutic benefits.
Uptake Kinetics – The rate at which oxygen is absorbed into blood plasma… #
Related terms: diffusion rate, oxygen transport Faster uptake kinetics are observed at higher pressures, explaining the rapid clinical improvement seen in certain acute conditions.
Ventilation‑Perfusion (V/Q) Mismatch – An imbalance between air flow and… #
Related terms: shunt, dead space ventilation HBOT can partially overcome V/Q mismatch by increasing dissolved oxygen independent of hemoglobin transport.
Venturi Mask – A device that delivers a precise FiO₂ by mixing oxygen wit… #
Related terms: oxygen mask, flow regulator In monoplace chambers, venturi masks are rarely used because the entire chamber is filled with oxygen, but they are relevant for pre‑treatment assessment.
Vibration Therapy – The application of mechanical oscillations to stimula… #
Related terms: mechanotherapy, adjunctive therapy Early studies suggest enhanced granulation when vibration is applied after hyperbaric sessions.
Wound Healing Phases – The sequential stages of tissue repair #
haemostasis, inflammation, proliferation, and remodeling. Related terms: granulation tissue, epithelialisation HBOT primarily augments the proliferative phase by delivering high oxygen levels that support fibroblast activity and collagen synthesis.
Wound Oxygen Tension – The partial pressure of oxygen within wound tissue… #
Related terms: tissue pO₂, oxygen diffusion Measurements taken before and after HBOT provide quantitative evidence of therapeutic impact.
Yield Strength – The stress at which a material begins to deform plastica… #
Related terms: material fatigue, safety factor Engineering specifications for hyperbaric chambers require yield strengths well above operational pressures to ensure long‑term durability.
Z‑Score – A statistical measure indicating how many standard deviations a… #
Related terms: statistical significance, confidence interval In hyperbaric studies, Z‑scores help determine whether observed improvements exceed random variation.