Methods: Vital capacity (VC) and its component expiratory capacity (ERV) and inspiratory capacity (IC) were detected in non-smoking healthy volunteers before and after breathing helium-oxygen mixture and the changes were compared.

• 方法测定非吸烟健康志愿者呼吸氦氧混合气体前后肺活量及其组成补呼气容积和深吸气量并比较它们的变化。