轻,中度体力负荷条件下外加吸气阻力的感觉阈限

以10名健康男青年为被试者,分别于静坐及轻、中度(200、600Kg.m.min~(-1))体力活动条件下观察了外加吸气阻力负荷所引起的面罩腔压力(P)及外呼吸功(w)变化;并采用辨别阈梯级(JND)与多级估量量表(MES)相结合的方法测出了不同体力负荷条件下的呼吸阻力感觉阈限。结果表明:(1)面罩腔压力与外呼吸功分别与呼吸感觉量值呈高度相关关系(P<0.01)但又以压力指标相关程度更为密切,故选用面罩腔压力波动幅度()作为反映呼吸感觉程度的客观生理指标较外吸气功率更为适宜。(2)体力负荷与外加吸气阻力对面罩腔压力、外呼吸功及感觉量值均具有协同的增强效应。(3)随体力负荷的增强,呼吸阻力感觉的阈限值也相应升高。在轻度体力负荷下能引起轻、中度呼吸阻力感觉的面罩腔压力波动幅度阈限值分别为(60、100mmH_2O);在中度体力负荷下,则分别为80、130mmH_2O。述结果对制订航空供氧装备附加呼吸阻力生理学标准具有实际意义。

THE DETECTON THRESHOLD FOR ADDED INSPIRATORY RESISTANCE AT LIGHT AND MODERATE WORK RATES

The changes in mask cavity pressure (P) and external respiratory work (W) elicited by added breathing loads were studied in 10 healthy young male subjects at rest and during light (200) and moderate (600 kgm. min-1) physical aactivities. The detection threshold for added resistance during different physical activities were determined by use of two kinds of psychological scales, i.e., the discriminability scale and Multistage Evaluation Scale (MES).The results found were: (1) the perceived magnitude (PM) of respirator sensation was highly correlated with P and W (P<0.01); (2) added resistance and physical load acted synergically in increasing the amplitudes of P,W or PM, i.e., the rate of change of the three variables with resistance was increased as physical activity strengthened; (3) the detection threshold for added resitance thus determined was also closely related to the strength of physical activity, e,g., adapting mask cavity pressure swing (P) as an index for physiological stimulus, the threshold values for light degree of respiratory sensation were 60 and 80 mmH2O during mild and moderate physical activity respectively, and the valuse for moderate degree of moderate degree of senstion were 100 and 130 mmH2O at the two work rates respctively.The significance of our findings in deriving physiological standards for allowable resistance of aircraft oxygen system is discussed.