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Heliox
Identifiers
CAS Number
PubChem CID
Chemical and physical data
FormulaHe.O2
Molar mass36.001

Heliox is a breathing gas mixture of helium (He) and oxygen (O2). It is used as a medical treatment for patients with difficulty breathing because this mixture generates less resistance than atmospheric air when passing through the airways of the lungs, and thus requires less effort by a patient to breathe in and out of the lungs. It is also used as a breathing gas for deep ambient pressure diving as it is not narcotic at high pressure, and for its low work of breathing.

Heliox has been used medically since the 1930s, and although the medical community adopted it initially to alleviate symptoms of upper airway obstruction, its range of medical uses has since expanded greatly, mostly because of the low density of the gas.[1][2] Heliox is also used in saturation diving and sometimes during the deep phase of technical dives.[3][4][5]

Medical uses

[edit]

There is also some use of heliox in conditions of the medium airways (croup, asthma and chronic obstructive pulmonary disease). A recent trial has suggested that lower fractions of helium (below 40%) – thus allowing a higher fraction of oxygen – might also have the same beneficial effect on upper airway obstruction.[6]

Patients with these conditions may develop a range of symptoms including dyspnea (breathlessness), hypoxemia (below-normal oxygen content in the arterial blood) and eventually a weakening of the respiratory muscles due to exhaustion, which can lead to respiratory failure and require intubation and mechanical ventilation. Heliox may reduce all these effects, making it easier for the patient to breathe.[7] Heliox has also found utility in the weaning of patients off mechanical ventilation, and in the nebulization of inhalable drugs, particularly for the elderly.[8] Research has also indicated advantages in using helium–oxygen mixtures in delivery of anaesthesia.[9]

Available forms

[edit]

In medicine, heliox may refer to a mixture of 21% O2 (the same as air) and 79% He, although other combinations are available (70/30 and 60/40).

Mechanism of action

[edit]

Heliox generates less airway resistance than air and thereby requires less mechanical energy to ventilate the lungs.[10] "Work of breathing" (WOB) is reduced by two mechanisms:

  1. increased tendency to laminar flow;
  2. reduced resistance in turbulent flow due to lower density.

Heliox 20/80 diffuses 1.8 times faster than oxygen, and the flow of heliox 20/80 from an oxygen flowmeter is 1.8 times the normal flow for oxygen.[11]

Heliox has a similar viscosity to air but a significantly lower density (0.5 g/L versus 1.25 g/L at STP). Flow of gas through the airway comprises laminar flow, transitional flow and turbulent flow. The tendency for each type of flow is described by the Reynolds number. Heliox's low density produces a lower Reynolds number and hence higher probability of laminar flow for any given airway. Laminar flow tends to generate less resistance than turbulent flow.

In the small airways where flow is laminar, resistance is proportional to gas viscosity and is not related to density and so heliox has little effect. The Hagen–Poiseuille equation describes laminar resistance. In the large airways where flow is turbulent, resistance is proportional to density, so heliox has a significant effect.

History

[edit]

Heliox has been used medically since the early 1930s. It was the mainstay of treatment in acute asthma before the advent of bronchodilators. Currently, heliox is mainly used in conditions of large airway narrowing (upper airway obstruction from tumors or foreign bodies and vocal cord dysfunction).

Usage in diving

[edit]
Effect of helium on a human voice
The effect of helium on a human voice
Problems playing this file? See media help.

Helium diluted breathing gases are used to eliminate or reduce the effects of inert gas narcosis, and to reduce work of breathing due to increased gas density at depth. From the 1960s saturation diving physiology studies were conducted with helium from 45 to 610 m (148 to 2,001 ft) over several decades by a Hyperbaric Experimental Centre operated by the French company COMEX specializing in engineering and deep diving operations.[12] Owing to the expense of helium,[13] heliox is most likely to be used in deep saturation diving. It is also sometimes used by technical divers, particularly those using rebreathers, which conserve the breathing gas at depth much better than open circuit scuba. Use of heliox mixtures is known as heliox diving, a subs-category of mixed gas diving, also known simply as gas diving.[14]

Heliox diving cylinder color coding: Illustration of cylinder shoulder painted in brown and white quarters
Illustration of cylinder shoulder painted in brown (lower) and white (upper) bands

The proportion of oxygen in a diving mix depends on the maximum depth of the dive plan, but it is often hypoxic and may be less than 10%. Each mix is custom made using gas blending techniques, which often involve the use of booster pumps to achieve typical diving cylinder pressures of 200 to 300 bar (2,900 to 4,400 psi) from lower pressure banks of oxygen and helium cylinders.

Because sound travels faster in heliox than in air, voice formants are raised, making divers' speech very high-pitched and hard to understand to people not used to it.[15] Surface personnel often employ a piece of communications equipment called a "helium de-scrambler", which electronically lowers the pitch of the diver's voice as it is relayed through the communications gear, making it easier to understand.

Trimix is a less expensive alternative to heliox for deep diving, which uses only enough helium to limit narcosis and gas density to tolerable levels for the planned depth.[16] Trimix is often used in technical diving, and is also sometimes used in professional diving.

In 2015, the United States Navy Experimental Diving Unit showed that decompression from bounce dives using trimix is not more efficient than dives on heliox.[17]

See also

[edit]
  • Argox – Gas mixture occasionally used by scuba divers for dry-suit inflation
  • Nitrox – Breathing gas, mixture of nitrogen and oxygen
  • Hydreliox – Breathing gas mixture of hydrogen, helium, and oxygen
  • Hydrox – Breathing gas mixture experimentally used for very deep diving
  • Trimix – Breathing gas consisting of oxygen, helium and nitrogen

References

[edit]

Further reading

[edit]
[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

Heliox

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from Grokipedia
Heliox is a mixture of (He) and oxygen (O₂). It is used medically to reduce and improve ventilation in patients with obstructive respiratory conditions, and in to prevent . Introduced clinically in by Alvan Barach for the treatment of and laryngeal obstructions, heliox leverages helium's low density—approximately one-seventh that of nitrogen—to convert turbulent airflow into more efficient laminar flow within narrowed airways, thereby decreasing the work of and enhancing . Common formulations include 70% helium and 30% oxygen (Heliox 70/30) or 80% and 20% oxygen (Heliox 80/20), with the oxygen proportion adjusted to meet the patient's needs while maintaining adequate oxygenation; higher oxygen blends, such as 50/50, may be used in cases of severe . In critical care settings, heliox is primarily indicated for acute exacerbations of and (COPD), where it reduces dynamic and respiratory effort; it is also effective for upper airway obstructions like , , and post-extubation in children and adults, as well as and . Administration requires specialized equipment, such as heated humidifiers and recalibrated ventilators, due to helium's high thermal conductivity and impact on gas measurements, ensuring safe delivery via face mask, , or .

Composition and Properties

Definition and Common Mixtures

Heliox is a binary mixture composed solely of (He) and oxygen (O₂), excluding or any other gases. This composition leverages helium's inert and low- properties to facilitate easier respiration in specific clinical and operational scenarios. In medical settings, the most common Heliox formulations are 70% helium and 30% oxygen (Heliox 70/30), utilized for general respiratory support in conditions involving airway obstruction, and 80% helium and 20% oxygen (Heliox 80/20), reserved for severe cases where supplemental oxygen demands remain low to avoid risks. These ratios balance helium's density-reducing effects with adequate oxygenation, and are commercially available as pre-mixed cylinders from suppliers adhering to pharmaceutical standards. For diving applications, Heliox mixtures are tailored to depth and requirements to mitigate issues like , with typical ratios such as 80% and 20% oxygen for deep commercial dives, or highly helium-dominant blends like 96% and 4% oxygen for extreme saturation dives below 100 meters to maintain safe oxygen partial pressures under high ambient pressures. Heliox is prepared by blending high-purity with oxygen in specialized cylinders or via inline blenders at the point of use, ensuring precise ratios through calibrated equipment. Medical-grade preparations comply with (USP) standards for purity and safety, typically using USP-grade gases to prevent contaminants that could impair respiratory function.

Physical and Chemical Properties

Heliox, a mixture primarily of helium and oxygen, is characterized by physical properties dominated by helium's low molecular weight of approximately 4 g/mol, in stark contrast to nitrogen's 28 g/mol. This results in a markedly reduced density for common Heliox mixtures compared to air; for instance, a 70/30 helium-oxygen blend has a density of about 0.55 g/L at standard temperature and pressure (STP), versus 1.29 g/L for air. Helium's contribution also imparts high thermal conductivity to Heliox, around 0.15 W/m·K for pure helium and approximately 0.13 W/m·K for an 80/20 mixture, far exceeding air's 0.026 W/m·K. Additionally, Heliox exhibits low viscosity, slightly higher than air at roughly 20 μPa·s compared to air's 18.5 μPa·s, though this difference is minor relative to the density reduction. The chemical properties of Heliox stem from helium's noble gas nature, rendering it chemically inert with no reactivity toward biological tissues or common substances under physiological conditions. The mixture is non-flammable as a whole, despite the oxidizing potential of its oxygen component. Helium's solubility in blood is notably low, with a Bunsen coefficient of about 0.0095 ml gas per ml blood per atm at 37°C, lower than nitrogen's 0.0115 under similar conditions, which minimizes inert gas accumulation in the body. Heliox's storage demands specialized cylinders due to helium's high diffusion rate through materials, necessitating enhanced seals and regular leak checks to contain the gas effectively, unlike storage for nitrogen-based mixtures. Key properties of Heliox compared to air and a typical nitrox mixture (32% oxygen, 68% nitrogen) are summarized below, highlighting differences in scale and impact:
PropertyAir (79/21 N₂/O₂)Heliox (80/20 He/O₂)Nitrox (32/68 O₂/N₂)
Density (g/L at STP)1.290.431.35
Viscosity (μPa·s at 20°C)18.520.418.6
Specific heat capacity (J/kg·K at 25°C)100523401010
Thermal conductivity (W/m·K at 25°C)0.0260.1300.027
These values are approximate for illustrative purposes, based on weighted averages for behavior; actual measurements may vary slightly with exact composition and conditions.

Mechanism of Action

Effects on Respiratory Flow

Heliox, a of and oxygen, alters respiratory flow dynamics primarily through its lower gas compared to air, which influences the nature of in the airways. The Reynolds number (Re), defined as Re=ρvdμRe = \frac{\rho v d}{\mu} where ρ\rho is gas , vv is , dd is airway , and μ\mu is , determines whether flow is laminar (low Re) or turbulent (high Re). Due to 's significantly lower (approximately 0.14 times that of in air), heliox reduces Re by about two-thirds at equivalent flow rates, shifting turbulent flow in narrowed airways toward laminar . This transition reduces , as generates higher resistance than in obstructed regions. According to Poiseuille's law for , Q∝1ηQ \propto \frac{1}{\eta} (where η\eta is ), but heliox's primary advantage stems from density reduction in segments, where resistance is density-dependent; although heliox has slightly higher , the net effect lowers overall resistance. In obstructive conditions, this can decrease the , particularly where predominates. The benefits are especially pronounced in smaller airways like the bronchioles, where high-velocity flow with air often results in during obstruction, amplifying resistance. Heliox promotes smoother, more efficient gas movement in these distal segments by minimizing . studies using airway models with simulated confirm these effects, demonstrating that heliox maintains through narrow passages where air induces , resulting in lower pressure drops and improved gas delivery efficiency. For instance, simulations of showed reduced and pressure gradients with increasing helium concentrations in heliox mixtures.

Physiological Impacts

Heliox enhances oxygenation in the lungs primarily through its lower compared to air, which facilitates faster of oxygen and better distribution to alveolar regions. This reduced promotes more uniform gas mixing and penetration into peripheral lung areas, thereby improving ventilation-perfusion (V/Q) matching and reducing areas of mismatch that can impair . In clinical settings, such as neonatal , heliox has been observed to alleviate V/Q mismatching, leading to improved oxygenation and decreased ventilatory requirements without significant alterations in overall respiratory mechanics. Despite these benefits, heliox introduces several potential side effects related to helium's physical properties. Its high thermal conductivity—approximately six times that of —accelerates heat dissipation from the and body surfaces, increasing the risk of , particularly during prolonged exposure or in cold environments. This heat loss can also manifest as a characteristic high-pitched voice change, resulting from the altered propagation in the lower-density gas mixture, which raises vocal formants without affecting the of . Cardiovascular effects of heliox are generally minimal, with little influence on gases or systemic in most applications. Breathing heliox typically does not alter pressures, , or ventricular filling pressures significantly, maintaining stable oxygenation and levels during short-term use. Overall, heliox's inert nature ensures negligible disruption to blood gas or cardiovascular function under normobaric conditions.

Medical Applications

Treatment of Obstructive Airway Diseases

Heliox serves as an adjunctive therapy in managing acute exacerbations of obstructive airway diseases, including , (COPD) with , and pediatric , by reducing and improving gas flow dynamics. In acute exacerbations, it mitigates bronchospasm-related resistance, facilitating better delivery and symptom relief when used alongside standard treatments like beta-agonists. For COPD patients experiencing during exacerbations, Heliox decreases dynamic and enhances exercise tolerance by promoting laminar airflow in narrowed airways. In pediatric , it provides temporary relief from upper airway obstruction, particularly in moderate to severe cases, by lowering the and hastening improvement in respiratory distress scores. Clinical evidence supports its efficacy in these settings, with a 2006 systematic review of 14 studies reporting an average 29.6% increase (95% CI 16.6–42.6%) in rate (PEFR) among patients breathing Heliox compared to air-oxygen mixtures. Subgroup analyses in severe have shown significant PEFR improvements of approximately 20 L/min with Heliox-driven nebulization. For , a 2021 Cochrane review of randomized trials indicated short-term benefits in moderate cases, with Heliox outperforming humidified oxygen in reducing severity scores, though evidence for mild cases remains inconclusive. The U.S. FDA has cleared Heliox delivery systems, such as the Precision Flow device, for emergency use in upper airway obstruction, including and exacerbations. Administration typically involves short-term delivery of a 70:30 or 80:20 helium-oxygen mixture via at flow rates of 8–15 L/min to maintain FiO2 above 0.21, lasting from hours to a few days until clinical stabilization. is transitioned to standard air-oxygen mixtures as decreases and oxygenation improves, avoiding prolonged use due to cost and logistical challenges. Recent developments include ongoing investigations into Heliox for chronic COPD maintenance. Earlier multicenter trials have confirmed reduced rates of mechanical ventilation and associated ICU admissions in severe exacerbations, supporting its role in averting intubation.

Other Clinical Uses

Heliox has been employed in the management of post-extubation stridor and laryngeal edema in intensive care unit (ICU) settings, where it provides effective respiratory support to alleviate upper airway obstruction and reduce the risk of reintubation. In a case involving a critically ill patient, heliox administration successfully mitigated severe stridor, avoiding immediate reintubation and associated complications such as prolonged mechanical ventilation. This benefit stems from heliox's lower density, which enhances laminar flow through narrowed airways. In pediatric care, heliox serves as an adjunct therapy for caused by viral infections, such as (RSV), by improving gas exchange and reducing the work of breathing in affected infants. Delivered via high-flow , heliox may reduce clinical respiratory distress scores in the short term (e.g., within the first hour). Clinical trials indicate that this approach decreases resistance, aiding in the stabilization of infants with moderate to severe symptoms. Emerging applications of heliox include its role as an adjunct in for (ARDS), where studies suggest potential reductions in ventilator days through decreased and improved gas distribution. Experimental models have shown heliox to enhance ventilation efficiency in ARDS, though large-scale clinical validation remains ongoing. Additionally, heliox holds promise in hyperbaric therapy for decompression illness, where its use during recompression may accelerate bubble resolution compared to air-oxygen mixtures. Key contraindications for heliox include the risk of hypoxia in patients requiring high fractional inspired oxygen (FiO2) levels, as the helium component can dilute oxygen delivery if not properly balanced. It is not recommended for long-term use due to elevated costs and global scarcity, which limits widespread availability. Treatment sessions typically cost $30 to $100 as of the early , though helium prices have surged to record highs (up to $117,660 per metric ton in 2025), influenced by ongoing supply chain disruptions that have periodically restricted medical-grade helium access.

Diving Applications

Use in Deep-Water Diving

Heliox finds primary application in commercial for underwater operations at depths exceeding 300 meters, such as maintenance on offshore , where teams of divers reside in pressurized chambers for weeks to perform extended tasks without repeated decompression. In these scenarios, divers connect via umbilicals to surface-supplied gas systems, enabling prolonged exposure to high-pressure environments while mitigating issues like . Similarly, in technical beyond 50 meters, recreational and professional divers use heliox in rebreathers or open-circuit systems for exploratory or salvage work, allowing safer penetration into deeper wrecks or caves. Mixture selection in these contexts prioritizes maintaining a of oxygen (PPO₂) equivalent to 0.21 atmospheres at the surface to ensure normoxia, with common ratios like 90% and 10% oxygen for bottom gases at extreme depths around 250 feet or more. For shallower segments above 100 meters, heliox is often blended with to form trimix, reducing usage and costs while still preventing narcosis. These adjustments are calculated based on planned depth and duration, with PPO₂ limits typically capped at 1.3-1.5 atmospheres during active work. Operational procedures begin with pre-breathing heliox in the surface chamber to wash out residual from prior air exposures, ensuring tissues saturate with during gradual compression to working depth. Once at depth, divers breathe the mixture at within saturation habitats or diving bells, transitioning seamlessly between chamber and underwater worksites via personnel transfer capsules. This setup supports multi-day excursions from the habitat, with gas supplied continuously to maintain physiological equilibrium. Specialized equipment, such as helium reclaim systems, captures and recycles over 90% of exhaled gas through scrubbing, compression, and purification processes, significantly lowering operational costs given helium's expense. These closed-loop systems, integrated into diving support vessels, filter out and before reintroducing the mixture, enabling efficient use during long-duration saturation missions at depths up to 500 meters.

Advantages and Limitations

Heliox offers several key advantages in deep-water diving environments. By replacing with , a non-narcotic , heliox eliminates the risk of , which impairs cognitive function and coordination at depths beyond approximately 30 meters when breathing air. Additionally, 's lower solubility in tissues compared to facilitates faster off-gassing during decompression, thereby minimizing overall exposure to hyperbaric conditions. When oxygen is carefully managed through appropriate mixture ratios, heliox also avoids central , a concern in high-pressure oxygen-enriched environments. Despite these benefits, heliox presents notable limitations that impact its practical use in diving. At depths exceeding 150 meters, rapid compression with helium-oxygen mixtures can induce (HPNS), characterized by tremors, myoclonic jerks, and reduced mental performance due to direct effects of inert gases under extreme pressure. Communication challenges arise from voice distortion, as the in heliox—approximately 1,000 m/s compared to 343 m/s in air—alters vocal formants, resulting in high-pitched, unintelligible speech that requires specialized unscramblers for effective diver-surface interaction. Furthermore, the high cost of , often exceeding $1,000 per dive day in commercial operations due to its scarcity and consumption rates, significantly increases logistical expenses compared to air or diving. As of 2025, ongoing global helium shortages have exacerbated these cost issues, prompting increased exploration of alternatives like trimix or other gas blends in diving operations. To mitigate these risks, established safety protocols emphasize gradual depth increases during compression to minimize HPNS onset, alongside continuous monitoring for early signs of helium-induced tremors through physiological assessments. Recent studies from 2022 highlight temporary post-dive effects on lung function, such as a decline in forced expiratory volume in one second (FEV1) following deep heliox exposure, which typically resolves within 24 hours with proper recovery. As an alternative for dives in the 50-100 meter range where HPNS is less prevalent, trimix (a blend of helium, nitrogen, and oxygen) is often preferred, as the addition of nitrogen helps suppress HPNS symptoms while still reducing narcosis compared to air.

History

Early Development

The concept of using helium-oxygen mixtures, or heliox, for deep diving originated in the early amid efforts to address the limitations of air as a . In 1919, researchers C.J. Cooke and Dr. Elihu Thompson proposed substituting for to mitigate the intoxicating effects of observed in deep dives, a problem increasingly evident during World War I-era salvage operations and development where divers experienced impaired judgment and coordination at depths beyond 100 feet. This motivation stemmed from the U.S. Navy's need for safer gases following incidents of narcosis and in compressed-air diving, prompting initial animal experiments to validate helium's inertness and low narcotic potential. The first practical tests of heliox occurred in 1924 when the U.S. Navy conducted hyperbaric chamber dives, confirming that helium-oxygen blends avoided narcosis at pressures equivalent to 300 feet. Building on this, Charles B. Momsen advanced heliox applications through the Navy's Experimental Diving Unit, established in , where key chamber experiments in 1937 pushed divers to simulated depths of 500 feet using heliox mixtures, demonstrating clear mental function without narcotic impairment and shorter decompression times compared to air. These proofs-of-concept laid the groundwork for operational use, culminating in 1939 when Momsen led the heliox-assisted rescue of 33 crew members from the sunken USS Squalus at 243 feet, marking the first large-scale application. Parallel to diving advancements, heliox entered medical practice in 1934 through trials led by Dr. Alvan L. Barach at , who tested helium-oxygen blends on patients with and upper airway obstructions. Barach's experiments showed that heliox's lower density reduced turbulent airflow resistance, easing breathing in four adult cases and two infant obstructions within minutes, with no adverse effects observed in supporting animal studies exposing mice to 79% helium-21% oxygen for extended periods. These findings, published in the Journal of the American Medical Association, highlighted heliox's therapeutic potential beyond diving. Commercial production of heliox mixtures emerged in the 1930s as helium extraction from fields scaled up, driven by post-WWI military demand; by 1937, costs had fallen to about $3 per , enabling broader availability for both diving and . Early patents, such as Max Eugene Nohl's 1937 design for a helium-compatible and , facilitated practical implementation. By the 1950s, the U.S. Navy formalized heliox protocols in its diving manuals, influencing international standards for mixed-gas , including precursors to ISO guidelines on gas purity and mixture specifications for hyperbaric environments.

Evolution in Medicine and Diving

In the 1960s, the United States Navy's SEALAB projects marked significant milestones in saturation diving using heliox mixtures, enabling aquanauts to live and work at depths up to 610 feet for extended periods. SEALAB I, deployed in 1964 off Bermuda at 192 feet, and subsequent iterations like SEALAB II in 1965 near La Jolla, California, at 203 feet, utilized helium-oxygen breathing gases to mitigate nitrogen narcosis and facilitate prolonged underwater habitation. These experiments validated saturation techniques, paving the way for deeper operations. By the 1970s, heliox saturation diving boomed in commercial offshore applications, particularly during North Sea oil platform installations starting around 1970 at sites like Ekofisk, where divers routinely used heliox to reach depths exceeding 300 meters for construction tasks. This era saw widespread adoption amid the global oil crisis, with heliox enabling efficient, multi-day dives that supported the rapid expansion of underwater infrastructure. Key advancements in diving included contributions from figures like , a oceanographer whose advocacy for in the 1960s influenced the development of manned submersibles. More recent from 2021 to 2024 has examined long-term physiological effects of single deep heliox dives, revealing temporary endothelial activation, , and damage at depths around 80 meters sea water, with recovery typically within 24 hours but potential implications for repeated exposures. These studies, including breath marker analyses post-dive, highlight ongoing concerns about vascular and pulmonary responses even in controlled saturation scenarios. In medicine, heliox saw renewed interest in the 1980s for emergency management of acute airway obstructions, with clinical resurgence in treating severe asthma exacerbations to reduce work of breathing before intubation. The 2000s expanded its pediatric applications, particularly via nebulizers delivering bronchodilators like albuterol in heliox-driven aerosols, which improved clinical outcomes in acute asthma by enhancing drug delivery and airflow in children. By the 2020s, integration with mechanical ventilators became more routine amid global helium shortages exacerbated by supply chain disruptions since 2019, prompting innovations like heated heliox delivery systems for neonates and COVID-19 patients to optimize ventilation while conserving gas. Brief references to its efficacy in COPD align with these developments, though detailed protocols remain in specialized applications. Global adoption of heliox has been informed by publications from organizations like Divers Alert Network (DAN), which discusses heliox in mixed-gas protocols for commercial dives at depths beyond 150 feet to prevent narcosis. The European Respiratory Society (ERS) supports its use in respiratory guidelines for obstructive diseases, emphasizing reduced in exercise and critical care settings. However, post-2010s helium supply volatility, including shortages from 2018-2020 and ongoing 2025 constraints, has challenged availability, raising costs for both diving operations and medical therapies while spurring research into gas conservation and alternatives.

References

  1. https://journals.physiology.org/doi/full/10.1152/japplphysiol.01365.2006
  2. https://pmc.ncbi.nlm.nih.gov/articles/PMC4093964/
  3. https://litfl.com/heliox/
  4. https://www.sciencedirect.com/topics/pharmacology-toxicology-and-pharmaceutical-science/heliox
  5. https://my.clevelandclinic.org/health/treatments/heliox
  6. https://www.sciencedirect.com/topics/nursing-and-health-professions/heliox
  7. https://www.lindedirect.com/healthcare-solutions/heliox-usp
  8. https://respiratory-therapy.com/disorders-diseases/chronic-pulmonary-disorders/helium-oxygen/
  9. https://dan.org/alert-diver/article/anatomy-of-a-commercial-mixed-gas-dive/
  10. https://homework.study.com/explanation/a-heliox-deep-sea-diving-mixture-contains-4-0-oxygen-and-96-0-helium-what-is-the-partial-pressure-of-oxygen-when-this-mixture-is-delivered-at-a-total-pressure-of-8-5-atm.html
  11. https://precisionmedical.com/wp-content/uploads/2022/06/505963_Rev10.pdf
  12. https://ca.healthcare.airliquide.com/solutions/medical-gases/heliox-helium-oxygen-7030
  13. https://www.liebertpub.com/doi/pdf/10.4187/respcare.06510608
  14. https://www.engineeringtoolbox.com/helium-d_1418.html
  15. https://go.drugbank.com/drugs/DB09155
  16. https://apps.dtic.mil/sti/tr/pdf/ADA286269.pdf
  17. https://www.airgas.com/msds/002095.pdf
  18. https://pmc.ncbi.nlm.nih.gov/articles/PMC3193060/
  19. https://pmc.ncbi.nlm.nih.gov/articles/PMC1794472/
  20. https://pmc.ncbi.nlm.nih.gov/articles/PMC10552068/
  21. https://pmc.ncbi.nlm.nih.gov/articles/PMC137275/
  22. https://www.ncbi.nlm.nih.gov/books/NBK542183/
  23. https://pmc.ncbi.nlm.nih.gov/articles/PMC2993714/
  24. https://pmc.ncbi.nlm.nih.gov/articles/PMC10092700/
  25. https://pubmed.ncbi.nlm.nih.gov/19029854/
  26. https://pmc.ncbi.nlm.nih.gov/articles/PMC7193706/
  27. https://pmc.ncbi.nlm.nih.gov/articles/PMC8960277/
  28. https://pmc.ncbi.nlm.nih.gov/articles/PMC5777660/
  29. https://pmc.ncbi.nlm.nih.gov/articles/PMC8377235/
  30. https://pmc.ncbi.nlm.nih.gov/articles/PMC9953147/
  31. https://www.researchgate.net/publication/7059872_The_history_and_physics_of_Heliox
  32. https://pubmed.ncbi.nlm.nih.gov/10966241/
  33. https://www.atsjournals.org/doi/10.1164/ajrccm.164.2.2006105
  34. https://associationofanaesthetists-publications.onlinelibrary.wiley.com/doi/10.1111/j.1365-2044.2006.04897.x
  35. https://pubmed.ncbi.nlm.nih.gov/24331390/
  36. https://pubmed.ncbi.nlm.nih.gov/34397099/
  37. https://www.prnewswire.com/news-releases/vapotherm-announces-fda-clearance-for-precision-flow-heliox-system-132691943.html
  38. https://www.aarc.org/news/thinking-outside-intubation-the-pros-and-cons-of-heliox-therapy/
  39. https://journals.lww.com/ccmjournal/fulltext/1998/01001/heliox_reduces_the_incidence_of_mechanical.312.aspx
  40. https://pmc.ncbi.nlm.nih.gov/articles/PMC11893200/
  41. https://pubmed.ncbi.nlm.nih.gov/40065892/
  42. https://pmc.ncbi.nlm.nih.gov/articles/PMC8504435/
  43. https://pubmed.ncbi.nlm.nih.gov/28506664/
  44. https://pmc.ncbi.nlm.nih.gov/articles/PMC2717432/
  45. https://pmc.ncbi.nlm.nih.gov/articles/PMC3573558/
  46. https://pubmed.ncbi.nlm.nih.gov/25662070/
  47. https://pubmed.ncbi.nlm.nih.gov/24986729/
  48. https://journal.chestnet.org/article/S0012-3692(16)34726-2/fulltext
  49. https://www.cruxinvestor.com/posts/helium-prices-surge-400-to-record-highs-as-global-supply-shortage-persist-in-the-rise-of-ai
  50. https://onlinelibrary.wiley.com/doi/10.1002/cphy.c130048
  51. https://www.dansa.org/blog/2022/12/04/how-deep-can-we-go
  52. https://pmc.ncbi.nlm.nih.gov/articles/PMC9767825/
  53. https://www.jfdglobal.com/submarine-platforms/atmosphere-monitoring-control/gas-management/electric-gasmizer-diver-gas-recovery-systems/
  54. https://pmc.ncbi.nlm.nih.gov/articles/PMC5801574/
  55. https://apps.dtic.mil/sti/tr/pdf/AD1000575.pdf
  56. https://www.ncbi.nlm.nih.gov/books/NBK470304/
  57. https://repository.si.edu/bitstream/handle/10088/2719/proceedings_asdw.pdf
  58. https://divermag.com/helium-riing/
  59. https://www.bbc.com/future/article/20250331-why-helium-shortages-are-worrying-the-world
  60. https://www.ncbi.nlm.nih.gov/books/NBK513359/
  61. https://pmc.ncbi.nlm.nih.gov/articles/PMC9731142/
  62. https://pubmed.ncbi.nlm.nih.gov/6142471/
  63. https://indepthmag.com/a-hundred-years-of-helium/
  64. https://dan.org/alert-diver/article/deep-in-the-science-of-diving/
  65. https://pubmed.ncbi.nlm.nih.gov/16723037/
  66. https://www.usni.org/magazines/proceedings/1965/february/sealab-i
  67. https://pmc.ncbi.nlm.nih.gov/articles/PMC11065503/
  68. https://www.atlasobscura.com/articles/what-is-a-saturation-diver
  69. https://www.whoi.edu/allyn-vine/
  70. https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2021.735986/full
  71. https://pmc.ncbi.nlm.nih.gov/articles/PMC10944665/
  72. https://pmc.ncbi.nlm.nih.gov/articles/PMC7003562/
  73. https://publications.aap.org/pediatrics/article/116/5/1127/68085/Helium-Oxygen-Driven-Albuterol-Nebulization-in-the
  74. https://www.frontiersin.org/journals/pediatrics/articles/10.3389/fped.2022.855050/full
  75. https://publications.ersnet.org/content/errev/19/115/30
  76. https://www.forbes.com/sites/brucelee/2019/05/24/there-is-a-helium-shortage-what-you-need-to-know/
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