[麻醉讀書筆記 78-day Anesthesia Secrets] Day 18 - Anesthesia Machine and Vaporizers

 

Anesthesia Secrets 78 Chapter, Day 18

🙀There is no shortcuts, only hard work. 💪


#Day 18- The Anesthesia Machine and Vaporizers

#Ref: Anesthesia Secrets, 4th edition. Chapter 18, 

The Anesthesia Machine and Vaporizers

The Anesthesia Machine and Vaporizers


[Basics]

目前美國有 2 major manufactures
  • Drager
  • Datex-Ohmeda

[Plumbing of an anesthesia machine]

簡單來說可以分成 3 個部分
  • Gas delivery system
  • The patient breathing system
  • A scavenger system


[如果牆壁上的管路沒有氧氣了怎麼辦]

這真的也是個滿有趣沒想過的問題 :)
→ 現在的麻機有 2 sources of gases: the wall outlet and E-cylinders (for Emergency)

A full green E-cylinder of O2 有 pressure: 2000 psi and about 625L 的 O2

  • O2: compressed gas → volume correlates linearly with the pressure
    • 1000 psi → 剩下 312L 的 O2
  • 有兩個作用: 給病人氧氣 + powers the ventilator bellows
    • 所以 receiving an oxygen flow of 2L/min and a minute ventilation of 8L/min → 那就會 10L of oxygen will be drained from the tank/min → 這個時候如果只剩下 312L O2 那就只能再用 31 mins
  • 如果發生緊急情況不能從牆壁給氧氣要從 E-cylinders → (3) 件事情: 降低 Oxygen flow rate + 轉成 hand-ventilate + 拿 oxygen tank 來
  • What should you do if you lose oxygen pipeline pressure? → Disconnect the pipeline connection at the wall (Why? Something is wrong with the oxygen pipeline. What if the supply problem evolves into a non-oxygen gas in the oxygen pipeline? If so, pipeline will flow (pressure 50 psi) rather than your oxygen cylinder source (down-regulated to 45 psi).) (Ref: Anesthesia Gas Machine)


[Vaporizer]



Saturated vapor pressures, 飽和蒸汽壓
  • 飽和蒸汽壓與沸點: 每一種物質在一密閉系統中,當其液態和氣態達到一動態平衡時,我們稱這時候物質蒸氣的壓力為飽和蒸汽壓。物質的蒸氣壓只隨物質的種類和溫度變化。當液體的蒸氣壓等於液面上的大氣壓力時,液體的內部會發生劇烈的汽化現象,此時的溫度稱為沸點。 (Ref: 科學 Online 高瞻自然科學教育平台)
  • The heat of vaporization is the energy required to release molecules of a liquid into the gaseous phase.

Desflurane Vaporizer → 很特別 
  • 因為 Desflurane has a vapor pressure of 664 mm Hg at 20 C. In other words the boiling point of this agent is approximately at room temperature, 沸點幾乎 = 室溫!
  • 所以 → The desflurane vaporizer actively heats the liquid agent to 39 C. At this temperature the vapor pressure of the agent is approximately two atmospheres. 才不會沸騰 XDD
  • The desflurane vaporizer actively injects vapor into the fresh gas stream, whereas all traditional vaporizers use a passive variable bypass system.

[A Scavenger]

### 清道夫, 腐蝕動物 ###

  • The device used to transfer this gas safely from the breathing circuit into the hospital vacuum system is called a scavenger.
  • providing both positive and negative relief valves

過年後的第一篇, 讀書囉 :) 
There is no shortcuts, only hard work.
Be safe and sound during the pandemics. Good luck.

By Mark, 馬克

💬 E-mail: mata.assembled@gmail.com


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