[麻醉讀書筆記 78-day Anesthesia Secrets] Day 02 - Respiratory and Pulmonary Physiology

 

Anesthesia Secrets 78 Chapter, Day 02

🙀There are no shortcuts, only hard work. 💪

Day 02 CM, Respiratory and Pulmonary Physiology

[基本 Lung Volume 名詞]

Lung Volume

FRC, Functional residual capacity

• Normal: 1.7-3.4L
• ↑ 增加
•  mem: 有 COPD 的老男胖子 FRC 大
• ↓ 減少
• mem: 躺著負壓高的ILD 病患 FRC 小
• posture: stand > prone > supine

Closing Capacity

• Key 🔑: during expiration, when SMALL AIRWAY begin to close
• young closing capacity: supine = 2/3 FRC
• 會讓 closing capacity ↑, [👾口訣CLOSE👾]: Cigarettes, LV failure, Old age, Surgery, Emphysema (& asthma)]
• ❗ Independent of position

動力學

• Resistance 就跟兩個相關 [Tube] and [Gas]
• Low (laminar) flow: [Tube] ∝ Length / (r*4 )
• High (Turbulent) flow: [Tube] ∝ 1/ (r*5 )
• → 應用: 所以如果 try weaning, 是因為↑ work of breathing → 可以 try larger size in diameter

Different zones of West, Perfusion and ventilation

(upright lung) [👾Mem👾]: 把 Alveolar 一個一個往後移動

- Zone 1 - no blood flow -  P Alveolar > P artery > P vein

- Zone 2 - moderate bf. - P a > P A > Pv

- Zone 3 - Greatest bf. -  a > v > Alveolar

• → wow → 把一個人 supine to supine → pulmonary blood flow ↑ 25-30%
• 究竟 P Alveolar = ?
• = Fi02, 0.21* (760 - PH2O, 47) - (PaCO2, 40 / RQ, 0.8) = 99.7

A-a gradient, Hypoxemia 的 DDx

• A-a gradient
• = PAO2 - PaO2 (normal = age/4 + 4, e.g. 60/4+4 = 16)
• Assessing the efficacy of gas exchange
• 應用

Hypoxemia, DDx (5)

Hypercapnia 的 DDx

Hypercapnia, DDx (3)

[豆🥜知識]

• Physiologic dead space = anatomic (2ml/kg, 60kg→120ml) + alveolar dead space (healthy pt → 0)
• HPV, Hypoxic pulmonary vasoconstriction → help maintain V/Q normal relationship
• CO2 在身體裡面
• dissolved: 7%
• HCO3-: 70%
• CO2-Hb: 23%
• Brain 呼吸中樞: bilateral medulla, pons

Ref: Anesthesia Secrets, 4th edition. Chapter 02

By 破掉的雞蛋, 🥚🥚🥚

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