急性低张性缺氧对机体的影响VIP免费

急性低张性缺氧对机体的影响Departmentofpathophysiology,N.Bethunecollegeofmedicalsciences,JilinUniversityCopyright©Dept.ofPathophysiology,N.Bethunecollegeofmedicalsciences2缺氧概念缺氧(hypoxia):各种原因导致的机体供氧减少或用氧障碍而引起组织细胞发生代谢、机能，甚至形态结构异常变化的病理过程。Copyright©Dept.ofPathophysiology,N.Bethunecollegeofmedicalsciences3缺氧的类型低张性缺氧以PaO2为特征血液性缺氧Hb数量或性质改变循环性缺氧组织血流量降低组织性缺氧组织细胞利用氧障碍Copyright©Dept.ofPathophysiology,N.Bethunecollegeofmedicalsciences4低张性缺氧(hypotonichypoxia)(一)概念以PaO2为特征的缺氧。(二)原因和机制吸入气氧分压过低大气性缺氧Copyright©Dept.ofPathophysiology,N.Bethunecollegeofmedicalsciences5低张性缺氧模型目的：复制低张性缺氧动物模型，观察急性低张性缺氧过程中机体的变化，并分析其机制。动物：家兔步骤：1.称重，全麻(3%戊巴比妥钠，1ml/kg)，固定，剪毛。2.气管插管，颈总动脉插管，剑突连拉力换能器描记呼吸。3.描记正常血压、心率、呼吸(频率、幅度)、口唇粘膜颜色。4.将气管插管与缺氧瓶连接，记录缺氧开始后5min,10min时上述指标变化。Copyright©Dept.ofPathophysiology,N.Bethunecollegeofmedicalsciences6缺氧瓶缺氧瓶结构吸入气压力及氧分压AtmosphereCathetersodalimeCopyright©Dept.ofPathophysiology,N.Bethunecollegeofmedicalsciences7讨论血氧变化特点注：组织用氧能力增强发绀(cyanosis):毛细血管中脱氧血红蛋白≥5g/dl，使皮肤、粘膜呈青紫色。PaO2血氧容量血氧含量SaO2A-V血氧含量差NCopyright©Dept.ofPathophysiology,N.Bethunecollegeofmedicalsciences8低张性缺氧对机体的影响呼吸系统代偿性反应急性PaO2(<60mmHg)颈动脉体、主动脉体化学感受器呼吸中枢兴奋呼吸运动肺泡通气量回心血量Copyright©Dept.ofPathophysiology,N.Bethunecollegeofmedicalsciences9缺氧对机体的影响-呼吸系统呼吸系统代偿性反应慢性肺通气变化的时相经过：1.PaO2肺通气呼吸性碱中毒CSFpH呼吸中枢抑制肺通气2.CSFHCO3-向组织液转移，由肾排出CSFpH正常PaO2中枢兴奋作用肺通气3.长期低张性缺氧外周化学感受器的敏感性肺通气增加不明显Copyright©Dept.ofPathophysiology,N.Bethunecollegeofmedicalsciences10缺氧对机体的影响-呼吸系统呼吸系统损伤性变化肺水肿肺动脉高压氧弥散障碍PaO21.缺氧外周血管收缩回心血量肺血量2.缺氧肺血管收缩肺血流阻力微血管通透性增高中枢性呼吸衰竭PaO2<30mmHg抑制呼吸中枢中枢性呼吸衰竭周期性呼吸潮式呼吸间停呼吸Copyright©Dept.ofPathophysiology,N.Bethunecollegeofmedicalsciences11缺氧对机体的影响-循环系统(一)代偿性反应缺氧性肺血管收缩心输出量增加缺氧交感神经兴奋心率心收缩力缺氧呼吸运动回心血量Kv通道，膜去极化,VDCCCa2+内流血管活性物质不平衡交感兴奋维持V/Q正常肺动脉高压缺氧缺氧肺血管收缩肺血管收缩Copyright©Dept.ofPathophysiology,N.Bethunecollegeofmedicalsciences12缺氧对机体的影响-循环系统(一)代偿性反应血流重新分布组织毛细血管密度增加HIF-1VEGF毛细血管增生，氧弥散距离,,组织供氧量血管平滑肌KCa和KATP超极化代谢产物交感兴奋皮肤内脏血管收缩心、脑血管扩张缺氧缺氧Copyright©Dept.ofPathophysiology,N.Bethunecollegeofmedicalsciences13缺氧对机体的影响-循环系统(二)损伤性变化肺动脉高压心肌舒缩功能降低①ATP能量供应不足②ATP心肌钙转运和分布异常③红细胞血液粘度心脏射血阻力④心肌收缩蛋白破坏心肌挛缩、断裂Copyright©Dept.ofPathophysiology,N.Bethunecollegeofmedicalsciences14缺氧对机体的影响-循环系统(二)损伤性变化心律失常①窦性心动过缓:迷走神经兴奋②期前收缩、传导阻滞、室颤：细胞内K+Na+心肌细胞兴奋性传导性回心血量减少①缺氧乳酸等血管扩张回心血量②呼吸中枢的抑制→胸廓运动Copyright©Dept.ofPathophysiology,N.Bethunecollegeofmedicalsciences15SomepictureusedinthisPowerPointfileisfromtheweb,thecopyrightisheldbytheoriginalcreatorofthematerial.