Objective To observe the influence of head-down tilt on visual evoked potential.Methods Six healthy volunteers were exposed to-6? head-down tilt.The visual evoked potential were measured before the test,the second day and the fifth day of the test under different space frequency.Results No significant difference was found in the latency of P100 before and after the test.The amplitude of P100 had significant change under high space frequency.But not the same happened on middle and low space frequency.Conclusion head-down tilt can induce the change of visual evoked potential under high space frequency,which means the weightlessness may influent the visual function.

Background Influence of weightlessness on visual function has been a hot topic in aerospace medicine field.Electroretinography (ERG) is valuable tool of evaluating visual function.Objective This study aims to observe the influence of head down tilt simulated weightlessness on ERG.MethodHead down tilt for 6° was adopted in 6 healthy volunteers.Flash ERG,including rod response,maxium response,cone response,oscillatory potentials (OPs) and 30 Hz flicker was recorded,and the latency and amplitude from each wave were analyzed before,two days and five days after trial.The record procedure followed the ISCEV standard for full field clinical electroretinography (2008 update).Oral informed consent was obtained from all the subjects prior to the trail.Results No significant differences were detected in the latencies and amplitudes of a,b waves of cone response and 30 Hz flicker among various time points(P＞0.05).The latencies were significantly prolonged in b wave of rod and a,b waves of maxim responses(P＜0.01),but no obvious change was found in amplitudes (P＞0.05).Both the latency and amplitude of all of the wavelets of OPs were considerably among the different time points(P＜0.05-0.01),and the ∑OPs was evidently different among the different time points(P＜0.05).Conclusion Head down tilt simulated weightlessness induce the abnormality of visual function in the early stage.

OBJECTIVETo evaluate the effectiveness of a helium-oxygen mixture (79%He- 21%O(2)) as an aerosolizing compressed gas for beta(2)-agonist therapy in patients with an asthma exacerbation.

METHODSTwenty-four patients in the outpatient department with a mild to moderate exacerbation of asthma were enrolled. The patients were randomly divided into an experimental group (13 cases) and a control group (11 cases). The experimental group inhaled Berotec with heliox-driven, and the control group inhaled Berotec with compressed air-driven. Eight hospitalized patients in the respiratory department with severe exacerbation of asthma were enrolled. The patients inhaled Berotec with heliox-driven or compressed air-driven in a random order.

RESULTSThe results of spirometric parameters and arterial blood-gas analysis were measured. In the mild to moderate asthma patients, no statistical differences between the two groups for forced vital capacity (FVC), forced expired volume in one second (FEV(1)), and expiratory flow in 50% forced vital capacity (FEF(50)) were presented. But the severe patients showed significant differences between heliox-driven and compressed air-driven for FVC, FEV(1), FEF(50) and partial pressure of oxygen (PaO(2)).

CONCLUSIONSCompared with the traditional inhalation of beta(2)-agonist therapy using compressed air-driven, the method of inhaling beta(2)-agonist with heliox-driven has more obvious benefits for those suffering from severe asthma. This is likely due to the cooperative effects between inhaling heliox on its physical gas properties and improving delivery of beta(2)-agonist in the treatment of exacerbation of severe asthma.

Adrenergic beta-Agonists ; administration & dosage ; Adult ; Asthma ; therapy ; Bronchodilator Agents ; administration & dosage ; Female ; Fenoterol ; administration & dosage ; Helium ; administration & dosage ; Humans ; Male ; Middle Aged ; Oxygen ; administration & dosage