呼吸生理与呼吸模式sam.pptVIP

* 31 * 33 * 34 34 34 34 34 18 Most ventilators currently on the market today terminate the inspiratory phase in Pressure Support Ventilation (PS) according to set termination criteria. This criteria is usually a percent of the peak flow for that particular breath. Clinicians have been limited in the past due to the inability to adjust this termination criteria. Expiratory Sensitivity (ESENS) defines the percentage of the projected peak inspiratory flow (VMAX) at which the ventilator terminates flow and thus cycles from inspiration to expiration during spontaneous breathing. A fixed PS termination criterion may potentially result in several clinical issues. If inspiratory flow terminates too early, it can lead to a decreased tidal volume, or increased inspiratory muscle load if the patients inspiratory effort persists after the ventilator has cycled flow off. Conversely, if inspiratory flow persists beyond patient effort which may happen when leaks are present, it can result in unnecessary expiratory work and patient/ventilator dysynchrony. * 26 * 36 * 39 * 40 * 41 * * * 43 * 44 * * 46 All inspiratory efforts unless Auto PEEP. You may want to not show a negatime inflection point on inspiration on some of these. Often there is not a negative deflection point, happens with aggressive inspiratory efforts. 呼气灵敏度 Esens与呼气WOB 医生可根据病人的情况调节Esens，使之符合病人内在的吸气相，可改善病人和呼吸机之间的同步性 PRESSURE FLOW PS overshoots target Esens fixed 25% Esens adjusted to 50% Normal Problem resolved 0 100 0 15 压力-时间曲线 流量-时间曲线 吸气触发灵敏度 呼气灵敏度 机械通气的呼吸模式——PSV通气方式（CPAP） 机械通气的呼吸模式——PSV通气方式（CPAP） 增加功能残气量(FRC),并可改善氧合 使塌陷的肺泡复原 扩张已打开的肺泡 使肺泡分布至肺毛细血管周围空间 可用于所有呼吸模式 5 cm H2O PEEP 机械通气的呼吸模式——PSV通气方式（CPAP） 优点： 预防和/或改善肺不张 改善氧合 潜在的副作用： 由于胸廓内正压的增加，使病人的心输出量降低 气压伤 增加颅内压 机械通气的呼吸模式——PSV通气方式（CPAP） 二、呼吸机的基本模式 呼吸机的基本概念 机械通气和心肺对抗 呼吸机的几个重要参数 呼吸模式 压力触发和流速触发 压力触发(Press.Trigger) 流速触发(Flow Trigger) 机械通气的触发方式——分类 触发灵敏度：病人的努力程度 达到触发灵敏度时，呼吸机将触发供气 触发可选择压力或流速触发 机械通气的触发方式——触发灵敏度 封闭回路：吸气阀和呼气阀关闭 病人横膈收缩，开始吸气动作 病人作功使呼吸