Pleura Flashcards
Explain the anatomical basis of a pneumothorax
- Accumulation of air in pleural cavity
- Rib fractures may damage parietal, visceral pleural & lungs when ends of ribs get jagged
- Air may enter pleural cavity during inspiration but fails to exit during expiration, causing accumulation of air in the pleural cavity
- } Negative pressure in pleural cavity is lost
- Pressure inside plural cavity ↑ with every inspiration
Open pneumothorax:
6. ↑ pressure inside cavity may collapse lung
7. Due to fracture damaging the thoracic wall, a one-way valve is formed and air from external environment does not escape
8. In closed pneumothorax, air fills in the pleural cavity from the inside
- Breathing causes accumulation of air aggravating the chest pain
- Collapsed lung and high pressure in each inspiration causes progressive shortness of breath
- Due to damaged ribs bleeding may occur; therefore accumulation of blood in pleural cavity which is usually detected at costodiaphragmatic recess (pleural effusion)
Rib fractures:
12. First 2 ribs are floating; less likely to fracture
13. Usually fracture @ their weakest point which is the angle of the ribs
14. The 1st rib is the strongest, broadest, flattest and most curved; is attached to 1st thoracic vertebra and to the manubrium via costal cartilage
Thoracic inlet + UL damage:
15. POST of manubrium, C1 & inner surface of 1st rib form the thoracic inlet
16. Subclavian artery + vein leave the inlet to supply upper limb
17. Damage to suprapleural membrane would result in pneumothorax ipsilaterally
18. Damage to 1st rib is likely to damage subclavian vessels, lower trunk of BP & suprapleural membrane
19. Subclavian artery damaged so blood supply to hand ↓, patient shows weak radial pulse
20. Due to vessel damage, hemorrhage occurs and blood accumulates in lower part of pleural cavity causing hemothorax
Explain the anatomical basis of a tension pneumothorax
- Condition where air enters pleural cavity but has no way of escape
- Causes loss of negative pressure in cavity & pressure rises
- Lung of same side collapses & due to ↑ pressure mediastinal structures shift to the opposite side
- Causes kinking of great vessels which is a life-threatening condition
Explain the anatomical basis of a mediastinal shift
- Observed by trachea shifting to opposite side
- Apex beat palpable in 5th IC space ANT axillary line
- Normal = 5th IC space mid clavicular line
What is the treatment for pneumothorax?
- Large bore needle inserted to pleural cavity @ 2nd IC space midclavicular line
- To decompress the tension, allowing the lung to expand
Explain the procedure of a thoracostomy
- Surgical procedure to evacuate air inside pleural cavity. 2 types: tube + needle
Needle:
→ Safe approach is second IC space @ midclavicular line
Tube:
→ Safe approach is 4th/5th IC space @ ANT axillary line
- Must always be inserted above upper border of lower rib of desired IC space; to avoid damage to IC neurovascular bundle
What is the safe triangle for IC tube?
- ANT border of latissimus dorsi
- LAT border of pectoralis major
- Line superior to horizontal level of nipple
- Apex is below the axilla
Explain how the neck is involved in pleura damage
- Pleura extends above 1st rib into root of neck superiorly undercover of suprapleural membrane
- } Can be damaged while inserting needle
Nerve supply of pleura
- Visceral pleura = autonomic nerves
- Parietal pleural :
→ Costovertebral pleura = IC nerve
→ Diaphragmatic pleura :
1. Central = phrenic n.
2. Peripheral = IC nerve
→ Mediastinal pleura = phrenic n.
Neurovascular bundle damage
- Neurovascular bundle travels along costal groove of a rib
- Lies @ inf. border of rib
- Lower border of rib is avoided when injection
- Inserted in upper border of lower rib of desired IC space
Layers in a stab wound
- Skin
- Subcutaneous tissue
- Pec. major
- Serratus ANT
- Ext. IC muscle
- Innermost IC muscle
- Endothoracic fascia
- Parietal pleura
- Visceral pleura
- Lung
→ In a stab wound: ball valve type of pneumothorax (defect acts as valve)
