Disease relevance of heliox

• Heliox in respiratory failure from obstructive lung disease [1].
• Heliox in chronic obstructive pulmonary disease: lightening the airflow [2].
• Heliox is a blend of helium and oxygen with a gas density less than that of air that decreases airway resistance (Raw) in patients ventilated for status asthmaticus [3].
• We conclude that heliox significantly improves carbon dioxide elimination and modestly improves oxygenation during HFOV in a model of acute lung injury [4].
• Does heliox decrease the need for intubation in acute bronchiolitis [5]?

Psychiatry related information on heliox

• Measurements were made in wakefulness and non-rapid eye movement (NREM) sleep, on 76%N2/24%O2 and on 76%He/24%O2 (heliox) [6].
• Psychometric evaluation of divers performing a series of heliox non-saturation dives [7].
• Continuous changes in electroencephalographic topograms and auditory reaction time during simulated 21 ATA (atmospheres absolute) heliox saturation dives [8].

High impact information on heliox

• We conclude that during acute asthma exacerbations, albuterol nebulized with heliox leads to a more significant improvement in spirometry when compared with albuterol nebulized with oxygen [9].
• Heliox improves lung deposition of inhaled particles when compared with air or oxygen inhalation [9].
• The heliox group had a significantly higher heart rate after albuterol nebulization compared with the control group [9].
• Following albuterol Treatment 1, the median change in forced expiratory volume in one second was 14.6% in the control group and 32.4% in the heliox group (p = 0.007) [9].
• On the basis of test lung data and plethysmography measurements, we also conclude that heliox improves carbon dioxide elimination primarily through increased tidal volume delivery [4].

Chemical compound and disease context of heliox

• There was no systematic difference between the two methods with regard to lung volume measurements: mean (SD) FRC values, corrected for body weight, were 22.9 (7.1) mL/kg for O2 and 23.4 (7.0) mL/kg for heliox [10].
• Neuronal sensitivity to pressure, barosensitivity, is illustrated by high-pressure nervous syndrome, which manifests as increased central nervous system excitability when heliox or trimix is breathed at >15 atmospheres absolute (ATA) [11].
• Compared to breathing nitrox, these data indicate that heliox improved the distribution of inspired gas, thereby recruiting more gas exchange units, improving gas exchange efficiency, reducing ventilatory and oxygen requirements, and attenuating lung inflammation [12].
• Fifteen out of 78 infants with acute bronchiolitis consecutively admitted to PICU fulfilled the inclusion criteria: clinical score>or=5 or arterial oxygen saturation (SatO2)<or=92% or PCO2>50 mmHg, despite supportive therapy, nebulized L-epinephrine, and heliox therapy through non-rebreathing reservoir facemask [13].
• The second trial, which recruited older patients (older than 40 years), showed greater improvement in PEF and dyspnea score with heliox-driven albuterol therapy in patients with lower pretreatment PEF [14].

Biological context of heliox

• Although heliox improved gas exchange during HFOV in our model, increased tidal volume delivery may limit clinical applicability [4].
• To study the effects of apneic pauses, sighs, and breathing patterns on functional residual capacity (FRC), we measured FRC repeatedly in 48 healthy preterm infants (weight at study 2,042 +/- 316 g [mean +/- SD], postconceptional age 36.6 +/- 2.0 wk), during unsedated sleep using a modified heliox/nitrogen washout technique [15].
• During Heliox breathing, there was a significant decrease in pulmonary resistance, resistive work of breathing, and mechanical power of breathing, whereas ventilation remained unchanged [16].
• Heliox improves hemodynamics in mechanically ventilated patients with chronic obstructive pulmonary disease with systolic pressure variations [17].
• OBJECTIVES: To determine the effect of breathing helium-oxygen (HELIOX) mixtures on pulmonary gas exchange during severe asthma [18].

Anatomical context of heliox

• Breathing a lower density gas mixture (Heliox) may have therapeutic value by decreasing the demands on the respiratory muscles and the caloric requirements for breathing [16].
• Heliox therapy for acute vocal cord dysfunction [19].
• In addition, the model suggests that switching to heliox breathing may prolong the existence of the bubble relative to breathing air for bubbles in spinal and adipose tissues [20].
• We visually followed the resolution of micro air bubbles injected into adipose tissue, spinal white matter, muscle, and tendon of anesthetized rats recompressed to and held at 284 kPa while rats breathed air, oxygen, heliox 80:20, or heliox 50:50 [21].
• Only the four bees in our sample with the highest body mass-specific thorax masses were able to hover in pure heliox [22].

Associations of heliox with other chemical compounds

• We wanted to know whether heliox (79% He, 21% O2) can be used instead of oxygen when determining functional residual capacity (FRC) [10].
• RESULTS: In both genotypes, exposure to 12 ATA heliox antagonized the allosteric enhancement of GABA(A) receptor function by flunitrazepam (0.1-10 microM) and pentobarbital (0.1-50 microM) but did not affect allosteric modulation by 3alpha-hydroxy-5beta-pregnan-20-one (0.1-1 microM) [23].
• BACKGROUND: Behavioral and biochemical studies indicate that exposure to 12 times normal atmospheric pressure (12 ATA) of helium-oxygen gas (heliox) is a direct, selective ethanol antagonist [24].
• METHODS: The effects of 12 times normal atmospheric pressure of helium-oxygen gas (heliox) versus ethanol (25-200 mM) potentiation of GABA-activated Cl- uptake in brain membranes (microsacs) from C57, LS, and SS mice were tested by using a 36Cl- flux assay [25].
• For a given setting of the ventilator, values of Trm and Trc were significantly lower with heliox than nitrox (P < 0.01), and the correlation between Trm and Trc were fair with both gases [26].

Gene context of heliox

• Effect of heliox on lung dynamic hyperinflation, dyspnea, and exercise endurance capacity in COPD patients [27].
• Spirometry, body plethysmography, maximal expiratory flow-volume curves (MEFV-curves) with air and with heliox (80% He + 20% O2) before and after inhalation of bronchodilators were studied in a group of 20 adult cystic fibrosis (CF) patients [28].
• Effect of heliox breathing on dynamic hyperinflation in COPD patients [29].
• These results indicate that exposure to 12 ATA heliox antagonizes ethanol-induced LORR in LS, 129 and C57 mice, but not in SS mice [30].
• TF was not affected by breathing Heliox [31].

Analytical, diagnostic and therapeutic context of heliox

• Heliox improves gas exchange during high-frequency ventilation in a pediatric model of acute lung injury [4].
• Expired gases of room air and a 70:30 mixture of heliox from the above ventilators were collected into a nondiffusing gas collection bag, and the volume was measured in a chain-compensated gasometer [32].
• DESIGN: A retrospective case-match control design was used to compare the changes in alveolar to arterial gradient [(A-a)gradient] in the first 2 hrs of mechanical ventilation (MV) for status asthmaticus (SA) in patients who received HELIOX with those who did not [18].
• Significant decreases in intensive care unit stay and in-hospital stay were observed for survivors in the heliox group [33].
• Preheliox DeltaPP correlated with the magnitude of reduction in intrinsic positive end-expiratory pressure during heliox ventilation [17].

References