野外與登山醫學--- 類固醇及其他藥物預防高海拔肺水腫 HAPE 機轉

在這篇文章有圖片說明機轉 . 類固醇 corticosteroids 能阻斷部分的路徑.  涵蓋 nitric oxide availability. nero-humoral axis, capillary leak, alveolar epithelial cells ENaC and Na/K/APTase pump activity.



http://www.dr-kowalski.ch/wp-content/uploads/2012/06/H%C3%B6henlungen%C3%B6dem.pdf

威而鋼/犀利士 增加肺循環中的一氧化氮NO, 造成肺血管張力下降(阻力下降, 壓力下降), 因此減少肺部微血管壓力及體液漏出至組織間隙和肺泡

類固醇增加肺循環 NO 使得肺血管張力下降, 減少缺氧引起的神經賀爾蒙活化, 減少肺微血管通透性, 改善缺氧引起的肺泡水分清除下降

氣管擴張劑藉由刺激 ENaC 增加肺泡水分清除

Fig 1. Action mechanisms of the different drugs used for prevention and treatment of high altitude pulmonary edema. Phosphodiesterase 5-inhibitors such as sildenafil and tadalafil increase nitricoxide availability in the pulmonary circulation leading to a decrease in pulmonary vascular tone; hence,pulmonary capillary pressure and fluid leakage in to the interstitial and alveolar space. Corticosteroids increase nitric oxide availability in the pulmonary circulation leading to a decrease in pulmonary vascular tone, decrease hypoxia associated neurohumoral activation and pulmonary capillary permeability, and enhance hypoxia-associated decrease in alveolar water clearance. β2 agonists enhance alveolar water clearance by stimulating ENaC.

(補充, 根據自己臨床經驗, 心因性肺水腫使用氣管擴張劑通常沒有效果, 很多病患反而使用擴張劑會一直感覺到呼吸更困難, 除非病患同同時合併肺水腫及慢性呼吸道阻塞疾病, 才會考慮使用氣管擴張劑作為治療)