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目的 探讨PHP动作对载人离心机致加速度性肺不张的防护作用.方法 试验采用的模拟空战曲线( SACM)包括2个各45 s的+4.5 Gz和2个分别为15 s和45 s的+5.0 Gz的平台,基线为+3.0 Gz (各30 s).7名志愿者呼吸浓度为100％的O2,在3种条件下进行SACM离心机暴露:A组,O2系统安全余压打开；B组,O2系统安全余压关闭；C组,O2系统安全余压关闭且采用PHP动作.结果 SACM暴露后,A组肺活量(VC)下降0.27 L,用力肺活量(FVC)和用力呼气量(FEV)均无显著变化,主观症状评分较低(2.5±2.6),胸部X线成像改变不明显.B组VC和FVC分别下降0.69 L(P ＜0.01)和0.29 L(P＜0.05),咳嗽、胸痛、吸气困难等主观症状明显,其评分(8.1±2.2)显著高于有安全余压时(P＜0.05),出现肺不张的典型影像学表现.C组VC和FVC无明显下降,无明显主观症状,主观感觉评分很低(0.8±0.9),与不采用PHP动作时的差异非常显著(P＜0.01),肺不张的影像学征象比不采用PHP动作时明显减轻.结论 采用PHP动作能够有效防止加速度性肺不张的发生.“,”Objective To explore the protective effects of PHP maneuver against centrifuge-induced acceleration atelectasis. Methods Seven subjects were exposed to centrifuge simulated aerial combat maneuvers (SACM) profile composed of two respective +4.5 Gz for 45 s and +5.0 Gz for 15 s and 45 s superimposed on + 3 Gz baselines.Using 100％ oxygen,experiment was carried out under 3 conditions:group A,with safety overpressure of 30 mm H2O to the mask; group B,without safety overpressure; group C,without safety overpressure,but with PHP maneuver.Chest X-ray,vital capacity (VC),forced vital capacity (FVC),forced expiratory volume ( FEV),and subjective ratings of chest pain,coughing,and shortness of breath were measured.Results Group A experienced an average of 0.27 L (P ＜0.05 ) reduction in post-SACM VC,and the subjective ratings were low (2.5 ±2.6).An average of 0.69 L (P ＜0.05 ) and 0.29 L (P ＜0.01 ) reduction in post-SACM VC and FVC were found in group B,and chest pain,coughing,and shortness of breath were reported by all subjects.The subjective ratings (8.1 ± 2.2 ) were higher than those of group A ( P ＜0.05 ).Six subjects had radiological changes typical of acceleration atelectasis.In group C,there was no significant reduction in post-SACM VC and FVC,and the subjective ratings (0.8 ±0.9) were lower than those of group B (P ＜0.01 ).There were still some radiological appearances of atelectasis in the same 6 subjects,but the severity was reduced obviously.Conclusion PHP maneuver can provide a satisfactory protection against centrifuge-induced acceleration atelectasis.