[麻醉讀書筆記 78-day Anesthesia Secrets] Day 03 - BLOOD GAS AND ACID-BASE ANALYSIS

 

Anesthesia Secrets 78 Chapter, Day 03

🙀There are no shortcuts, only hard work. 💪

Day 03 - BLOOD GAS AND ACID-BASE ANALYSIS

[基本概念👶]

• ABG 提供了基本的重要 3 種資訊
1. Oxygenation ← PaO2 (Oxygen dissolved in the blood)
2. Ventilation ← PaCO2
3. Acid-base status

• 簡單的快速判讀 ABG
• [STEP 01] 先判讀 👶

• 基本判讀	Primary	Compensate
  Resp. acidosis	PaCO2 ↑	HCO3- ↓
  Resp. alkalosis	PaCO2 ↓	HCO3- ↓
  Met. acidosis	PaCO2 ↓	HCO3- ↓
  Met. alkalosis	PaCO2 ↑	HCO3- ↑

  
  
• [STEP 02] 判讀是不是合理的 Compensation 還是有合併其他的? 👦
• 介紹一個把小麻數字簡化的快速 mem 方法 → 1234, 5/4, 3/4 上下上下

compensation 判讀 (from 高榮 NEPH Dr. 謝志杰)

• 怎麼使用呢?
• 正常的 compensate, *0.1, *0.3...

• [STEP 03] 判斷 Anion Gap, AG 👨
• = 到底計算的是甚麼? → 是 💥UNMEASURED ANION (-) 💥
• = Na - (HCO3 + Cl)
• normal = 12 +/- 4
• 記得 correct → observed AG + 2.5* (4 - observed albumin level) (mem: 2.5*4=10)

[ 💣常見原因 💣]

• Respiratory
• Acidosis (CO2 retention)
• drugs (residual anesthetics, NMB
• asthma, emphysema
• Obesity hypoventilation
• CNS, NMB
• Alkalosis (CO2 washout)
• Sepsis
• Hypoxemia
• CNS lesion
• Anxiety / pain
• Metabolic
• Acidosis
• AG ↑: accumulation of unmeasured anions (-)
1. Lactic acid
2. Ketones
3. Toxins (甲醇, 乙醇, Salicylates)
4. Uremia
• Alkalosis

[Talk about Buffer System 🚰🚰]

• ION
• HCO3- (Fastest)
• Alb -
• Intracellular protein -
• PO4 3-
• Organ
• Lung
• Kidney
• Liver (production / metabolism of acids)
• GI tract

[豆🥜知識]

• ABG 裡面的 BE (Base Excess)
• normal: -3 ~ 3 mmol/L
• 代表的是: physiologic "non-bicarbonate" buffers
• 對於 Acute metabolic acidosis
• many clinicians initiate treatment of metabolic acidosis when the 
• bicarbonate <5 mEq/L) (Ref: UpToDate, 2021)
• pH < 7.1 (Ref: UpToDate, 2021)
• → roughly, by experience: 給 BE level /2 支 sodium bicarbonate
• ❗❗❗ 注意 
• CO2 → 是 Measured 測到的
• ABG 的 HCO3- → 是算出來的 Calculated value

Ref: Anesthesia Secrets, 4th edition. Chapter 03

By 破掉的雞蛋, 🥚🥚🥚

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