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PNEUMOTHORAX

Definition

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Classification / Types

1. Spontaneous Pneumothorax

• Occurs in the absence of underlying lung disease
• Typically tall, thin young males (M:F = 6:1), 20–30 years
• Caused by rupture of subpleural blebs/bullae (apical)
• Risk factors: smoking, Marfan syndrome, family history

• Occurs as a complication of underlying lung disease
• More dangerous — less cardiopulmonary reserve
• Causes: COPD/emphysema (most common), asthma, TB, cystic fibrosis, Pneumocystis pneumonia, lung abscess, malignancy

2. Traumatic Pneumothorax

• Penetrating chest trauma (stab wound, gunshot)
• Blunt chest trauma (rib fractures lacerating lung)
• Iatrogenic: central line insertion, thoracentesis, lung biopsy, mechanical ventilation (barotrauma), tracheostomy

3. Tension Pneumothorax

• Air enters pleural space via a one-way valve mechanism
• Progressive air accumulation → increasing intrapleural pressure
• Life-threatening emergency: collapses ipsilateral lung, displaces mediastinum, compresses contralateral lung and great veins → reduced venous return → cardiovascular collapse
• Causes: penetrating trauma, mechanical ventilation (PEEP), failed intercostal tube

4. Open Pneumothorax (Sucking Chest Wound)

• Open communication between pleural space and atmosphere
• Air moves through the defect with each breath ("sucking" sound)

5. Catamenial Pneumothorax

• Rare; associated with thoracic endometriosis
• Occurs within 24–72 hours of menstruation, right-sided predominantly

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Pathophysiology

• Negative pressure is lost → elastic recoil of lung causes collapse
• Degree of collapse depends on volume of air and compliance of lung
• In tension pneumothorax, each breath traps more air → intrapleural pressure rises above atmospheric → mediastinal shift → kinking of SVC/IVC → obstructive shock

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Clinical Features

Symptoms

Signs

Tension Pneumothorax — Clinical Triad

• Tracheal deviation away from affected side
• Absent breath sounds + hyper-resonance
• Hemodynamic instability (hypotension, tachycardia, raised JVP)

⚠️ Tension pneumothorax is a clinical diagnosis — do NOT wait for X-ray confirmation before treatment. (Bailey & Love's Surgery, 28th Ed., p. 395)

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Investigations

1. Chest X-Ray (Erect PA — First Line)

• Visible pleural line (visceral pleural edge) with absent lung markings beyond it
• Lung collapse (partial/complete)
• In tension: mediastinal shift, depressed ipsilateral diaphragm, contralateral lung compression

• Small: visible rim < 2 cm at level of hilum
• Large: visible rim ≥ 2 cm at level of hilum

2. CT Chest (Gold Standard)

• Confirms diagnosis when CXR is equivocal
• Identifies underlying bullae/blebs, quantifies size accurately
• Best for secondary pneumothorax with underlying lung disease

3. FAST Ultrasound

• Absence of "lung sliding" sign on M-mode
• Presence of "barcode/stratosphere sign" (normal: "seashore sign")
• Rapid, bedside, especially useful in trauma

4. ABG

• May show hypoxemia, hypocapnia (compensatory hyperventilation)
• Severe: respiratory acidosis (tension PTX)

5. ECG

• Tachycardia
• Decreased voltage on affected side
• May mimic anterior MI (rarely)

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Management

A. Tension Pneumothorax — Emergency Treatment

1. Immediate needle decompression:
   • 14–16G cannula into 2nd intercostal space, midclavicular line (MCL), affected side
   • Hissing of air confirms diagnosis
2. Followed by intercostal chest drain (ICD):
   • 5th ICS, anterior axillary line ("safe triangle")

B. Simple/Spontaneous Pneumothorax — BTS Guidelines

C. Intercostal Chest Drain (ICD)

• Position: 5th ICS, anterior axillary line (triangle of safety)
• Triangle of safety: anterior border of latissimus dorsi, lateral border of pectoralis major, 5th ICS
• Connected to underwater seal drainage
• Remove when: lung fully expanded + no air leak for 24 hours

D. Surgical Management — Video-Assisted Thoracoscopic Surgery (VATS)

• 2nd ipsilateral recurrence
• 1st recurrence in bilateral/contralateral PTX
• Persistent air leak > 5–7 days
• Haemopneumothorax
• Occupational risk patients (pilots, divers) after first episode

E. Chemical Pleurodesis

• Agents: Talc (most effective), tetracycline, bleomycin
• Induces pleural symphysis → prevents recurrence
• Done via ICD or at VATS

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Complications

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Key Differentials

• Acute MI (especially in young patient with chest pain)
• Pulmonary embolism
• Pleuritis
• Aortic dissection
• Giant emphysematous bulla (mimics PTX on CXR)

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High-Yield Points for MD Exam

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Prognosis

• PSP: Excellent prognosis; 25–30% recurrence rate without surgery; near-zero after VATS pleurodesis
• SSP: Depends on underlying disease; higher morbidity and mortality
• Tension PTX: Fatal if untreated; full recovery if promptly decompressed

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PNEUMOTHORAX — COMPLETE ELABORATED ANSWER

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1. DEFINITION

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2. SURGICAL / APPLIED ANATOMY OF THE PLEURAL SPACE

• The pleural cavity is a potential space bounded by:
  • Visceral pleura: covers the lung surface
  • Parietal pleura: lines the chest wall, diaphragm, and mediastinum
• Normal pleural fluid volume: 5–15 mL (lubricating layer)
• Intrapleural pressure: −5 to −8 cmH₂O at rest; −15 to −20 cmH₂O during inspiration
• This negative pressure is generated by the opposing elastic recoil of the lung (tending to collapse) and chest wall (tending to expand)
• Pleural fluid dynamics: produced from parietal pleural capillaries (Starling forces — net secretion ~11 mmHg); reabsorbed mainly by visceral pleural capillaries (pulmonary circulation, net absorbing pressure ~6 mmHg) (Bailey & Love's, 28th Ed., p. 999)
• Elastic recoil of the lung contributes ~4 mmHg negative pressure, favouring lung expansion as long as the pleural seal is intact

When this seal is broken and air enters the pleural space, negative pressure is lost and the lung collapses due to its own elastic recoil.

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3. CLASSIFICATION — DETAILED

A. Spontaneous Pneumothorax

i. Primary Spontaneous Pneumothorax (PSP)

• No clinically apparent underlying lung disease
• Incidence: 18–28/100,000/year (males), 1.2–6/100,000/year (females)
• Peak age: 20–30 years
• Body habitus: tall, thin, lean males (low BMI → stretched lung apices)
• Pathology: rupture of subpleural emphysematous blebs or bullae at lung apices
  • Blebs: intrapleural air collections within visceral pleural layers
  • Bullae: intraparenchymal air spaces > 1 cm diameter
• Mechanism: high alveolar-to-pleural pressure gradient at apex (gravity-dependent ventilation:perfusion mismatch) → ischemia → bleb formation → rupture
• Risk factors:
  • Smoking (relative risk increased 20-fold in heavy smokers) — most important modifiable factor
  • Marfan syndrome, homocystinuria, Ehlers-Danlos syndrome (connective tissue disorders)
  • Family history (autosomal dominant tendency)
  • Cannabis smoking
  • Scuba diving, high-altitude activities

ii. Secondary Spontaneous Pneumothorax (SSP)

• Complicates existing pulmonary pathology
• More serious — reduced cardiopulmonary reserve leaves less tolerance
• Causes:

B. Traumatic Pneumothorax

i. Penetrating Trauma

• Stab wounds, gunshot wounds, impalement injuries
• Air enters directly through chest wall defect or via lacerated lung/bronchus

ii. Blunt Trauma

• Rib fractures → lacerate visceral pleura
• Sudden compression → alveolar rupture
• Tracheobronchial tears

iii. Iatrogenic (Most Common Cause Overall in Hospitals)

• Central venous catheter insertion (subclavian > internal jugular) — most common
• Thoracentesis / pleural aspiration
• Pleural biopsy
• CT-guided lung biopsy / FNAC
• Mechanical ventilation (barotrauma/volutrauma, especially with high PEEP)
• Positive pressure ventilation
• Tracheostomy
• Intercostal nerve blocks
• Acupuncture (rare)

C. Tension Pneumothorax

• One-way ball-valve mechanism: air enters pleural space during inspiration but cannot escape during expiration
• Progressive rise in intrapleural pressure above atmospheric → ipsilateral lung collapse → mediastinal shift → compression of contralateral lung → kinking/compression of SVC and IVC → reduced venous return → obstructive shock
• Without treatment: fatal within minutes
• Causes: penetrating chest wounds, mechanical ventilation, faulty ICD (clamped/blocked), traumatic pneumothorax with valvular flap

D. Open Pneumothorax (Sucking Chest Wound)

• Large chest wall defect (> 2/3 of tracheal diameter) → air preferentially enters through wound rather than trachea
• Audible "sucking" sound with each breath
• Leads to paradoxical breathing, ventilation failure
• First aid: 3-sided occlusive dressing (Asherman seal) — allows air out but not in

E. Catamenial Pneumothorax

• Rare condition (< 5% of all pneumothoraces in women)
• Thoracic endometriosis — diaphragmatic defects allow peritoneal air/endometrial implants to reach pleura
• Occurs within 24–72 hours of onset of menstruation
• Almost exclusively right-sided (98%)
• Recurrence inevitable without hormonal therapy
• Treatment: hormonal suppression (GnRH analogues, OCP) + VATS excision of endometriotic deposits + diaphragm repair + pleurodesis

F. Neonatal Pneumothorax

• Occurs due to high transpulmonary pressures during first breaths
• Complication of meconium aspiration syndrome, RDS, vigorous resuscitation

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4. PATHOPHYSIOLOGY — IN DEPTH

Air enters pleural space
         ↓
Loss of negative intrapleural pressure
         ↓
Lung elastic recoil → lung collapses
         ↓
Ventilation-perfusion mismatch → Hypoxemia
         ↓
Compensatory tachypnoea + sympathetic activation
         ↓ (if tension)
Progressive air accumulation (ball-valve)
         ↓
Rising intrapleural pressure → mediastinal shift
         ↓
Contralateral lung compression (↓ ventilation)
SVC/IVC kinking (↓ venous return)
         ↓
Obstructive shock → cardiac arrest

Physiological Consequences:

Fistulous Mechanisms (Air Leak Pathways):

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5. CLINICAL FEATURES — DETAILED

Symptoms

• Pain: described as "tearing" or "knife-like", typically worsens with breathing
• Symptoms may be surprisingly mild in PSP (young, healthy lungs can compensate)
• Symptoms typically begin at rest or with mild activity (NOT during strenuous exercise — distinguishes from cardiac causes)

Signs

Classic Tension Pneumothorax Presentation — "5 Ds"

1. Dyspnoea (severe, progressive)
2. Distended neck veins (raised JVP)
3. Deviation of trachea (away from affected side)
4. Decreased breath sounds (ipsilateral)
5. Drop in BP (hypotension/shock)

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6. INVESTIGATIONS

A. Chest X-Ray (Standard Erect PA)

• Visible visceral pleural line (white line) with no lung markings beyond it
• Hyperlucency of affected hemithorax
• Partial or complete lung collapse — lung retracted toward hilum
• Depression of ipsilateral hemidiaphragm (in large PTX)
• Widening of intercostal spaces (in large PTX)

• Mediastinal shift away from affected side
• Tracheal deviation away from affected side
• Compression of contralateral lung
• Flattening/depression of ipsilateral diaphragm

• Small: visible rim of air < 2 cm at level of hilum
• Large: visible rim of air ≥ 2 cm at level of hilum
• A 2 cm rim corresponds to approximately 50% lung volume loss

• PTX may appear as deep sulcus sign — abnormally deep, lucent costophrenic angle
• Hyperlucency of upper abdomen
• Lung edge may not be visible — easy to miss

B. CT Chest — Gold Standard

• Most accurate for sizing and characterizing pneumothorax
• Identifies underlying blebs, bullae, emphysema, malignancy
• Distinguishes PTX from giant emphysematous bullae (important — wrong treatment if misdiagnosed)
• Quantifies size accurately when CXR is equivocal
• Detects occult pneumothorax (missed on plain film)
• Guides surgical planning (identifies bleb location)

C. Ultrasound (FAST/POCUS — increasingly used in trauma/ICU)

• Sensitivity 86–98%, Specificity ~100% for PTX detection
• Advantage: bedside, no radiation, faster than CXR in emergencies

D. Arterial Blood Gas (ABG)

E. ECG

• Sinus tachycardia (most common)
• Rightward QRS axis shift (right-sided PTX)
• Decreased R-wave amplitude / electrical alternans (mimics pericardial effusion)
• T-wave inversions in anterior leads (right-sided)
• May mimic anterior STEMI — important differential

F. Other

• Peak flow/spirometry: reduced FEV1, FVC on affected side
• Oximetry: SpO₂ monitoring
• Blood tests: FBC, CRP (if infective cause suspected); LDH, ADA (if TB or malignancy suspected)

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7. DIFFERENTIAL DIAGNOSIS

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8. MANAGEMENT — COMPREHENSIVE ALGORITHM

STEP 1: Is it Tension Pneumothorax?

If YES → Do not wait for imaging — treat immediately

Tension Pneumothorax Management:

1. High-flow O₂ (15 L/min via non-rebreather mask) — immediately
2. Emergency needle decompression:
   • 14–16G IV cannula
   • 2nd ICS, midclavicular line (MCL), upper border of 3rd rib (to avoid neurovascular bundle)
   • Hissing of air = confirms diagnosis
   • Converts tension → simple pneumothorax
3. Definitive: Intercostal chest drain (ICD):
   • Insert into 5th ICS, anterior axillary line (triangle of safety)
   • Attach to underwater seal drain
4. If IV access/decompression not possible: open thoracostomy (trauma setting)

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STEP 2: Simple Spontaneous Pneumothorax — BTS Algorithm

Is it symptomatic? / Is the patient breathless?
            |
    YES ←——|——→ NO
     |                    |
   Large?              Small PSP (<2cm)?
(≥2cm rim)              |
     |              YES ——→ Observe, discharge with safety advice
     ↓                      High-flow O₂ if admitted
 Needle Aspiration           Review in 2-4 weeks with CXR
 (1st line attempt)
     |
 Successful? → YES → Observe 1h → CXR → Discharge + review
     |
    NO
     ↓
 Intercostal Chest Drain (ICD)
     |
 Persistent air leak > 3-5 days?
     ↓
 VATS / Surgical consultation

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STEP 3: Needle Aspiration (Simple Aspiration) — Technique

• Indication: Large/symptomatic PSP, first attempt before ICD
• Equipment: 16G cannula + 50 mL syringe + 3-way tap
• Site: 2nd ICS, MCL (or 4th/5th ICS, anterior axillary line)
• Procedure: Aspirate until resistance felt, patient coughs, or 2.5 L air aspirated
• Success: CXR after 1 hour shows expanded lung → discharge
• Failure: Recurrence/failure → proceed to ICD
• Success rate: ~60–80% in PSP; not recommended in SSP (proceed directly to ICD)

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STEP 4: Intercostal Chest Drain (ICD)

Triangle of Safety (BTS):

• Anterior border: lateral border of pectoralis major
• Posterior border: anterior border of latissimus dorsi
• Inferior border: level of 5th ICS (nipple level)
• Apex: axilla

Technique:

1. Position: patient supine or 45°, arm raised above head
2. Landmark: 4th or 5th ICS, midaxillary line
3. Anaesthetize skin, subcutaneous tissue, rib periosteum, parietal pleura (lidocaine 1%)
4. Blunt dissection into pleural space (never trocar directly — risk of injury)
5. Insert finger to confirm pleural space, clear adhesions
6. Advance drain (28–32F for haemopneumothorax; smaller for simple PTX)
7. Connect to underwater seal drain (UWS)
8. Secure with suture, apply occlusive dressing

Underwater Seal Drain:

• Bottle filled with sterile water to 2 cm depth
• Long tube submerged — creates water seal
• Swinging: water level oscillates with respiration → confirms correct placement
• Bubbling: indicates ongoing air leak
• No swinging + no bubbling: drain is blocked OR lung is fully expanded

When to Remove ICD:

• Lung fully re-expanded on CXR
• No air bubbling for 24 hours
• Drain fluid output < 150–200 mL/day (if haemothorax)
• Remove at end-expiration with Valsalva (or end-inspiration — depends on local protocol)
• Apply occlusive dressing immediately on removal

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STEP 5: Surgical Management

Indications for Surgery (VATS):

• 2nd ipsilateral spontaneous pneumothorax
• 1st episode with bilateral or contralateral pneumothorax
• 1st episode in high-risk occupations (pilots, divers, parachutists)
• 1st episode with haemopneumothorax
• Persistent air leak > 5–7 days despite ICD
• Failure of lung expansion with ICD
• Spontaneous pneumothorax in remote areas (profession/geography)
• Patient preference after fully counselled

VATS Procedure: (Bailey & Love's, 28th Ed., p. 1002)

1. Deal with air leaks — staple/oversew bullae, close fistulae
2. Search for and obliterate blebs and bullae (bullectomy)
3. Make the visceral pleura adherent to the parietal pleura (pleurodesis) — so subsequent leaks are contained

Three Methods of Pleural Adhesion:

Chemical Pleurodesis Agents:

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9. MANAGEMENT IN SPECIAL SITUATIONS

Ventilated Patients (ICU)

• High risk of tension pneumothorax due to positive pressure ventilation
• Always insert ICD (needle aspiration insufficient)
• Use smaller Seldinger-technique drains for simple PTX
• Clamping ICD in ventilated patient is contraindicated (risk of tension)

HIV/AIDS Patients with PCP

• SSP with PCP has high recurrence rate (~50%)
• Persistent air leaks common due to necrotic lung tissue
• Early surgical referral; consider pleurodesis early

Pregnant Patients

• Rare; same management principles
• CXR safe in pregnancy (shielded)
• Avoid prolonged hypoxia — fetal risk
• ICD preferred over observation if significant

Bilateral Simultaneous Pneumothorax

• Very rare; life-threatening
• Bilateral ICDs + urgent surgical referral

Haemopneumothorax

• Blood + air in pleural space
• Occurs in 5% of spontaneous PTX (from torn adhesions/vessels)
• Requires large-bore ICD (28–32F)
• Surgery if > 1.5 L blood drained immediately or > 200 mL/hr ongoing

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10. COMPLICATIONS

Immediate

Related to ICD

Late Complications

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11. PROGNOSIS AND RECURRENCE

• Most recurrences in PSP occur within 6–24 months
• Risk of contralateral PTX: ~10–15% over lifetime
• PSP mortality: < 0.1%
• SSP mortality: up to 10% (due to underlying disease)

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12. PREVENTION AND PATIENT ADVICE

• Smoking cessation — most important preventive measure
• Avoid scuba diving until lung function confirmed normal AND after surgical cure
• Avoid unpressurized air travel for at least 1 week (BTS: wait for full resolution; most airlines recommend 6 weeks post-pneumothorax before flying)
• Avoid vigorous Valsalva manoeuvres (heavy weight-lifting, playing brass instruments)
• Alert future healthcare providers to previous PTX history (risk of re-expansion during any positive pressure ventilation)
• Follow-up CXR to confirm complete re-expansion before return to activity

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13. HIGH-YIELD EXAM SUMMARY TABLE

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