PULMONARY PHYSIOLOGY-WORK OF BREATHING

SUMMARY

1. 5% cardiac output expended in ventilation. 5% of total resting oxygen consumption. Might increase to 30% with hyperventilation.

2. This is from tissue resistance (lung, chest wall), pressure for flow (airways, upper/lower).

3. If patients in cardiogenic shock, intubation can improve survival as it decreases work of breathing.

4. Maximum Inspiratory Pressure (MIP): 100-120mmHg in a normal human being. However people only require 3-4 mmHg for normal breathing.

5. Respiratory muscles can fatigue. Types of fatigue: central, transmission (nerve)-related, contractile.

6. Causes of muscle fatigue: abnormal muscle, abnormal blood flow, hyperinflation, dystrophy, shock, airflow obstruction.

Reference(s)

Wilkinson, I., Furmedge, D. and Sinharay, R. (2017). Oxford handbook of clinical medicine. Oxford: Oxford University Press. Get it on Amazon.
Feather, A., Randall, D. and Waterhouse, M. (2020). Kumar And Clark’s Clinical Medicine. 10th ed. S.L.: Elsevier Health Sciences. Get it on Amazon.
Hannaman, R. A., Bullock, L., Hatchell, C. A., & Yoffe, M. (2016). Internal medicine review core curriculum, 2017-2018. CO Springs, CO: MedStudy.
Therapeutic Guidelines. Melbourne: Therapeutic Guidelines Limited. https://www.tg.org.au [Accessed 2021].