Heliox delivered by high flow nasal cannula improves oxygenation in infants with respiratory syncytial virus acute bronchiolitis / Heliox administrado por cânula nasal de alto fluxo melhora a oxigenação em crianças com bronquiolite aguda por vírus sincicial respiratório

Abstract Objective: The objective of this study is to evaluate the hypothesis that use of heliox would result in improvement of gas exchange when used with high flow nasal cannula in infants with RSV acute bronchiolitis. Methods: All patients that met the inclusion criteria were randomized to either heliox (70:30) or air-oxygen mixture 30% via high flow nasal cannula at 8 L/min for a continuous 24 h. Measurements were taken at baseline, after 2 h, and at the end of the 24 h. Results: This prospective study included 48 patients. After 2 h of treatment with heliox, the oxygen saturation and PaO2 significantly improved when compared with the air-oxygen group, 98.3% vs. 92.9%, 62.0 mmHg vs. 43.6 mmHg (p = 0.04 and 0.01), respectively. Furthermore, PaO2/FiO2 ratio was significantly higher in the heliox group when compared with the air-oxygen group, 206.7 vs. 145.3. Nevertheless, CO2 showed better elimination when heliox was used, without significance. MWCA score dropped significantly in the heliox group, 2.2 points vs. 4.0 points in air-oxygen (p = 0.04), 2 h after starting the therapy. Conclusion: Transient improvement of oxygenation in infants with RSV acute bronchiolitis during the initial phase of the therapy is associated with heliox when provided with HFNC, may provide a precious time for other therapeutic agents to work or for the disease to resolve naturally, avoiding other aggressive interventions.

Resumo Objetivo: Avaliar a hipótese de que o uso da mistura heliox resultaria em melhoria da troca gasosa quando usado com cânula nasal de alto fluxo em crianças com bronquiolite aguda por VSR. Métodos: Todos os pacientes que atenderam aos critérios de inclusão foram randomizados para receber a mistura heliox (70:30) ou a mistura ar/oxigênio a 30% por meio da cânula nasal de alto fluxo a 8 L/min por 24 horas contínuas. As medições foram feitas no início, depois de duas horas e ao fim de 24 horas. Resultados: Fizemos um estudo prospectivo em que foram incluídos 48 pacientes. Após duas horas de tratamento com a mistura heliox, a saturação de oxigênio e a PaO2 apresentaram melhoria significativa em comparação com o grupo da mistura ar/oxigênio: 98,3% em comparação com 92,9%, 62,0 mmHg em comparação com 43,6 mmHg (p = 0,04 e 0,01), respectivamente. Além disso, a relação PaO2/FiO2 era significativamente mais alta no grupo da mistura heliox do que no grupo da mistura ar/oxigênio, 2.067 em comparação com 1.453. Contudo, o CO2 apresentou melhor eliminação quando a mistura heliox foi usada, sem relevância. O Escore MWCA caiu significativamente no grupo da mistura heliox, 2,2 pontos em comparação com 4,0 pontos da mistura ar/oxigênio (p = 0,04) duas horas após o início da terapia. Conclusão: A breve melhoria da oxigenação em crianças com bronquiolite aguda por VSR na fase inicial da terapia está associada à mistura heliox quando administrada pela CNAF e poderá fornecer um tempo precioso para outros agentes terapêuticos funcionarem ou para a própria doença se curar naturalmente e evitar outras intervenções agressivas.

Special mechanical ventilation:heliox ventilation and partial liquid ventilation / 中国小儿急救医学

Neonatal mortality has been significantly decreased because of the development of neo-natal respiratory support techniques. Nevertheless,constant and high frequency ventilators have some limita-tions to solve all problems in neonatal respiratory failure. Special mechanical ventilation,mainly including he-liox and partial liquid ventilation,provides new respiratory support for newborn infants. The clinical signifi-cance of heliox and partial liquid ventilation need further investigation.

Heliox no tratamento do mal asmático: relato de casos / Heliox in the treatment of status asthmaticus: case reports

RESUMO O hélio foi descoberto em 1868 pelo astrônomo francês Pierre-Jules-César Janssen e teve seu uso terapêutico pela primeira vez na obstrução das vias aéreas, feito por Barach, quase 70 anos depois, em 1934. O heliox é caracterizado por sua baixa densidade, o que lhe confere melhor fluidez sob condições de turbulência, minimizando a pressão das vias aéreas e facilitando a ocorrência de um fluxo laminar. Este artigo apresenta dois casos clínicos de doentes com mal asmático sob ventilação mecânica, refratários à terapêutica, em que se recorreu ao heliox, permitindo uma otimização da eficácia do tratamento farmacológico convencional. Apesar de sua utilização permanecer esporádica e sua verdadeira eficácia não se encontrar bem demonstrada, as propriedades físicas únicas do hélio e a melhoria teórica do fluxo de ar nas vias aéreas obstruídas fomentam o interesse e a pesquisa científicos. Sua aplicação pode ter lugar simultaneamente em terapêuticas convencionais nas exacerbações graves e refratárias da doença obstrutiva grave.

ABSTRACT Helium was discovered in 1868 by the French astronomer Pierre-Jules-César Janssen and was first used as a therapeutic treatment for airway obstruction by Barach almost 70 years later, in 1934. Heliox is characterized by its low density, which makes it more fluid under conditions of turbulence, thus minimizing airway pressure and facilitating the occurrence of laminar flow. The present article describes two clinical cases of patients with status asthmaticus subjected to mechanical ventilation and refractory to treatment in whom heliox was used, which allowed optimization of the efficacy of conventional pharmacological treatments. Although heliox is still used sporadically and its true efficacy has not been well demonstrated, the unique physical properties of helium and the theoretical improvement of the airflow in obstructed airways have produced scientific interest and stimulated research. Heliox can be used simultaneously with conventional therapies in cases of serious and refractory exacerbations of severe obstructive disease.

Application of heart rate and rating of perceived exertion scale in monitoring physical fatigue in divers during heliox saturation diving / 第二军医大学学报

Objective To study the application of heart rate(HR) and rating of perceived exertion(RPE) scale in monitoring the physical fatigue in the divers during the 100 msw heliox saturation diving. Methods The 100 msw pressure environment was simulated by a 500 msw saturation diving system: pressure was 1.1 MPa; oxygen partial pressure was 35-52 kPa; carbon dioxide partial pressure was <0.5 kPa;the temperature during exposure to high pressure was (31.0±1.7)℃;and the relative humidity was (76.8±3.5)%. Respiratory gas was heliox. The 18 divers' HR and the scores of RPE scale were recorded at 6 time points, including (1)the day before the subjects entered the chamber; (2) the first day that the subjects were exposed to 100 msw pressure environment; (3) the peak of the subject physical exercise load test under 100 msw pressure environment; (4) the second day under 100 msw pressure environment; (5) the first day that the subjects were out of the chamber; and (6) the seventh day that the subjects were out of the chamber. All the data were analyzed with paired-samples t-test. The correlation was analyzed with Pearson correlation. Results From the day before the subjects entered the chamber to the first day that the subjects were exposed to 100 msw pressure environment, the resting HR of subjects was significantly decreased (P<0.05); From the first day that the subjects were out of the chamber to the seventh day that the subjects were out of the chamber, the resting HR was significantly increased (P<0.05). Significant differences were also found in the basic RPE score of the subjectes between before entering the chamber and after entering the chamber(P<0.05). During the 100 msw heliox saturation, with the variable physical work loads, the trend of of heart rate changes was still in accordance with the score of RPE scale, with that measured at the peak of the subject physical exercise load test under 100 msw pressure being significantly different from that measured at the first day the subjects were exposed to 100msw pressure (P<0.05).The RPE score was significantly related with the HR of divers (r=0.734, P<0.01). Conclusion The combined application of HR and RPE scale can monitor the physical fatigue of the divers during 100msw heliox saturation diving.

Comparison of common decompression tables for routine heliox diving / 军事医学

To meet the requirements for the development of marine resources and military operations, divers usually dive deeper than the depth at which narcosis is present during air diving.Under this condition, heliox is required for this div-ing.Sofar, some countries have developed their own decompression tables for routine heliox diving.The best-known is tables from USA and France.In the preceding century, tables of Former Soviet Union and France used for routine heliox diving were introduced into China.On the basis of both types of tables,Chinese Navy developed their own tables for this purpose. In this paper, we summarized the characteristics of these tables from 5 countries and compared them in terms of structure, oxygen use, total decompression time, first stop and other features.This may provide a basis for future modification of ta-bles used in China and the development of new tables for routine heliox diving.

Development of heliox-recirculating respirator based on ADuC848 / 医疗卫生装备

From the treatment of respiratory failure, the method of breathing heliox is presented. This paper introduces the heliox-recirculating respirator based on ADuC848 which realizes PID control of heliox output through the measurements of the pressure in gas path, oxygen concentration, temperature and so on. The electronic measurement & control unit is described in detail.