Oxygenation Performance of Different Non-Invasive Devices for Treatment of Decompression Illness and Carbon Monoxide Poisoning.

Study Objective: Application of high concentrations of oxygen to increase oxygen partial pressure (pO2) is the most important treatment for patients with carbon monoxide intoxication or divers with suspected decompression illness. The aim of this study was to evaluate the oxygenation performance of various non-invasive oxygen systems. Methods: The effect of different oxygen systems on arterial pO2, pCO2 and pH and their subjective comfort was evaluated in 30 healthy participants. Eight devices were included: nasal cannula, non-rebreather mask, AirLife Open mask, Flow-Safe II CPAP device, SuperNO2VA nasal PAP device, all operated with 15 L/min constant flow oxygen; nasal high-flow (50 L/min flow, 1.0 FiO2), non-invasive positive pressure ventilation (NPPV, 12 PEEP, 4 ASB, 1.0 FiO2) and a standard diving regulator (operated with pure oxygen). Results: Diving regulator, SuperNO2VA, nasal high-flow and NPPV achieved mean arterial pO2 concentrations between 538 and 556 mm Hg within 5 minutes. The AirLife Open mask, the nasal cannula and the non-rebreather mask achieved concentrations of 348-451 mm Hg and the Flow-Safe II device 270 mm Hg. Except for the AirLife open mask, pCO2 decreased and pH increased with all devices. The highest pH values were observed with NPPV, diving regulator, Flow-Safe II and nasal high-flow but apparent hyperventilation was uncommon. The AirLife Open and the non-rebreather mask were the most comfortable, the SuperNO2VA and the nasal cannula the most uncomfortable devices. Conclusion: A standard diving regulator and the SuperNO2VA device were equally effective in providing highest physiologically possible pO2 as compared to nasal high-flow and NPPV.

Low-Flow Nasal Cannula Hydrogen Therapy.

BACKGROUND: Molecular hydrogen (H2) is a biologically active gas that is widely used in the healthcare sector. In recent years, on-site H2 gas generators, which produce high-purity H2 by water electrolysis, have begun to be introduced in hospitals, clinics, beauty salons, and fitness clubs because of their ease of use. In general, these generators produce H2 at a low-flow rate, so physicians are concerned that an effective blood concentration of H2 may not be ensured when the gas is delivered through a nasal cannula. Therefore, this study aimed to evaluate blood concentrations of H2 delivered from an H2 gas generator via a nasal cannula. METHODS: We administered 100% H2, produced by an H2 gas generator, at a low-flow rate of 250 mL/min via a nasal cannula to three spontaneously breathing micro miniature pigs. An oxygen mask was placed over the nasal cannula to administer oxygen while minimizing H2 leakage, and a catheter was inserted into the carotid artery to monitor the arterial blood H2 concentration. RESULTS: During the first hour of H2 inhalation, the mean (standard error (SE)) H2 concentrations and saturations in the arterial blood of the three pigs were 1,560 (413) nL/mL and 8.85% (2.34%); 1,190 (102) nL/mL and 6.74% (0.58%); and 1,740 (181) nL/mL and 9.88% (1.03%), respectively. These values are comparable to the concentration one would expect if 100% of the H2 released from the H2 gas generator is taken up by the body. CONCLUSIONS: Inhalation of 100% H2 produced by an H2 gas generator, even at low-flow rates, can increase blood H2 concentrations to levels that previous non-clinical and clinical studies demonstrated to be therapeutically effective. The combination of a nasal cannula and an oxygen mask is a convenient way to reduce H2 leakage while maintaining oxygenation.

Neuroergonomic and psychometric evaluation of full-face crew oxygen masks respiratory tolerance: a proof-of-concept study.

INTRODUCTION: Preventing in-flight hypoxia in pilots is typically achieved by wearing oxygen masks. These masks must be as comfortable as possible to allow prolonged and repeated use. The consequences of mask-induced facial contact pressure have been extensively studied, but little is known about mask-induced breathing discomfort. Because breathlessness is a strong distractor and engages cerebral resources, it could negatively impact flying performances. METHODS: Seventeen volunteers (age 20-32) rated respiratory discomfort while breathing with no mask and with two models of quick-donning full-face crew oxygen masks with regulators (mask A, mask B). Electroencephalographic recordings were performed to detect a putative respiratory-related cortical activation in response to inspiratory constraint (experiment 1, n=10). Oxygen consumption was measured using indirect calorimetry (experiment 2, n=10). RESULTS: With mask B, mild respiratory discomfort was reported significantly more frequently than with no mask or mask A (experiment 1: median respiratory discomfort on visual analogue scale 0.9 cm (0.5-1.4), experiment 1; experiment 2: 2 cm (1.7-2.9)). Respiratory-related cortical activation was present in 1/10 subjects with no mask, 1/10 with mask A and 6/10 with mask B (significantly more frequently with mask B). Breathing pattern, sigh frequency and oxygen consumption were not different. CONCLUSIONS: In a laboratory setting, breathing through high-end aeronautical full-face crew oxygen masks can induce mild breathing discomfort and activate respiratory-related cortical networks. Whether or not this can occur in real-life conditions and have operational consequences remains to be investigated. Meanwhile, respiratory psychometric and neuroergonomic approaches could be worth integrating to masks development and evaluation processes.

The OxyMask(™) development and performance in healthy volunteers.

BACKGROUND: The OxyMask(™) is a unique, open-style, oxygen mask that was originally developed in 2005. The original mask was modified, using computational fluid dynamics numerical simulations, with the goal of allowing it to produce a wider range of FiO(2). This analysis was used to guide the modification of the mask shell and the location for the oxygen diffuser. METHODS: The new OxyMask was attached to 10 healthy subjects and used to deliver escalating levels of oxygen (1.5, 2, 2.5, 3, 5, 10, 15, 20, 25 and 30 LPM) for 90 seconds at each level and the resulting FiO(2) was recorded (at the lips) from 5 consecutive measurements at each oxygen flow rate. RESULTS: Mean FiO(2) was 25.4% at 1.5 LPM of oxygen, 30.1% at 2 LPM, 36.5% at 2.5 LPM, 41.8% at 3 LPM, 57.6% at 5 LPM, 74.4% at 10 LPM, and 80.1% at 15 LPM. Each FiO(2) achieved at these escalating oxygen levels was significantly greater than all the previous levels. The mean FiO(2) was 82.8 at 20 LPM, 84.2% at 25 LPM and 84.3% at 30 LPM. All of these values on average were not significantly greater than the FiO(2) achieved with 15 LPM. In a few subjects a maximum FiO(2) of 90% was reached. CONCLUSION: The original OxyMask was successfully modified so that the second generation of the mask can provide a wide range of FiO(2), from 25% to 90%, while keeping its unique open design.

Sequential treatment of neonatal hypoxic ischemic encephalopathy with a modified oxygen mask in an air-pressurized chamber / 中华物理医学与康复杂志

Objective To observe the efficacy, benefits and shortcomings of pressurized air therapy for neo- natal hypoxic ischemic encephalopathy (HIE). Methods One hundred and nine neonates with HIE were treated with hyperbaric oxygen (HBO) with a continuing oxygen supplement from an improved oxygen mask plus a 2.5-1itre breathing sacculus proprius in a large air-pressurized oxygen chamber. Among them there were 70 cases treated with 3-6 courses of HBO + drug therapy, 39 cases treated with a single session of HBO + drug therapy, and 32 treated with drug therapy alone. Motor development was assessed using the Chinese infantile intelligence development test scale at the ages of 3, 6 and 12 months. Results The sequential HBO + drug group achieved significantly better average motor development than the single session group or the drug only group. There was mo significant difference between the single treatment group and the drug only group. The proportion of abnormal CT results 12 months after treatment was significantly higher in the drug only group than in the sequential HBO + drug group. Conclusion Sequential HBO + drugs therapy with the improved oxygen mask is preferable to a single session of HBO + drug treatment or drug therapy alone.