Tension pneumothorax Flashcards
List some DDx for a presentation of:
- traumatic MVA injury to L chest and abdomen
- severe chest pain
- SOB
PDx. Tension pneumothorax DDx. • Respiratory o Lung contusion (lung parenchyma injury -> blood and oedema in alveolar spaces) o Tension pneumothorax o Haemothorax o PE (long bone fracture, post-MI) o Acute exacerbation of asthma/COPD • Cardiac o Pericardial effusion (secondary to laceration by fractured rib) -> tamponade o Cardiogenic shock o Aortic dissection o MI, angina • GIT o Oesophageal perforation (w straining/vomiting)- Boerhaave’s syndrome (transmural rupture), MW tear (not transmural) o Pancreatitis (due to seat belt trauma) • MSK- rib fracture, muscular injuries • Psychiatric- anxiety disorder (panic attack)
How would you assess this pt?
Primary survey:
A) airway obstruction, manoeuvres, caution C-spine injury
B) RR, O2 %, added sounds, air entry, percussion, tracheal deviation, rib fractures, subcut emphysema (tension pneumo)
C) HR, BP, temp, cap refill, heart sounds, JVP
D) GCS, pupils, pain
E) Temp, exposure and examine injuries
F) Fluid status- hypovolaemic shock
Secondary survey: head to toe exam, log-roll, X-ray, ECG
List the signs of a pneumothorax?
What indicates a tension pneumothorax?
Pneumothorax signs (P-THORAX mnemonic): P- Pleuritic chest pain T- Tracheal deviation H- Hyper-resonance O- Onset sudden R- Reduced breath sounds and dyspnoeas A- Absent fremitus X- X-ray shows collapse
Tension pneumo also has:
- agitation
- tachycardia
- pulsus paradoxus (inspiration increases intrathoracic pressure)
- hypotension
- progressive cyanosis
- air hunger
- cold skin
- shock
- distended neck veins
What investigations would you do?
• First action: thoracentesis (needle thoracostomy), later replaced by LTM chest drain Imaging: - CXR - CT - ECG - eFAST scan (extended focused assessment with sonography in trauma) Bloods: - FBC (normocytic anaemia due to acute haemorrhage) - CRP/ESR - EUC - LFT - Amylase, lipase - Coag panel - Troponins - ABG - Cross match, group and hold
Describe the x-ray findings for a tension pneumothorax?
- dark space outlined by visible pleural margin of collapsed lung
- loss of vascular lung markings in this region
Describe the anatomy of the lung?
Trachea: tube of c-shaped cartilaginous rings anteriorly, trachealis muscle posteriorly -> flexibility during swallowing
o Bifurcation T4 -> splitting into R main bronchus (2.5cm, wider, shorter, more vertical) AND L main bronchus (5cm)
• Lung apex: protrudes above thoraxic inlet, extends 3-4cm above 1st costal cartilage
• 2 lobes in left lung, 3 lobes in right lung
• Fissures:
o Oblique fissure: bilateral, begins 5th rib head -> line of 6th -> inferior border
o Horizontal fissure: R lung
• Hilum:
o R (superior to inferior): aparterial bronchus, pulmonary artery, hyparterial bronchus, inferior pulmonary vein
o L: pulmonary artery, bronchus, inferior
Describe the arterial supply of the lungs?
1) SVC -> RA -> RV -> L and R pulmonary arteries -> alveolar capillaries (exchange CO2 for O2) -> pulmonary veins -> L and R superior and inferior pulmonary veins -> LA
2) Bronchial arteries: thoracic aorta -> 2 L bronchial a.s. and 1 R bronchial a -> non-resp lung regions (bronchi, nerves, vessel walls, visceral pleura)
Describe the venous drainage of the lungs?
IVC -> azygous v -> SVC
Describe the innervation of the lungs?
1) anterior and posterior pulmonary plexuses
2) vagus nerve -> sensation from pulmonary vessel walls, bronchi, visceral pleura -> brainstem
2) Parasympathetic supply: vagus -> pulmonary plexus -> smooth m constriction, increased glandular secretion
4) Sympathetic supply: sympathetic ganglion (T1-4) -> pulmonary plexus -> smooth muscle relaxation, inhibits glandular secretion
Describe the lymphatic drainage of the lungs?
Bronchopulmonary LNs -> tracheobronchial LNs -> bronchomediastinal trunk (bilaterally)
Describe the difference between a primary and secondary spontaneous pneumothorax?
• Primary spontaneous pneumothorax- ruptured subpleural bleb (small subpleural thin walled air containing spaces)
o Risk factors- smoking, FMHx, Marfan’s syndrome, Homocystinuria, thoracic endometriosis
•Secondary spontaneous pneumothorax- rupture of subpleural bleb (apical)
o Risk factors- underlying lung disease (COPD, CF, primary/mets lung ca, necrotising pneumonia), trauma (open wound, fractured rib, iatrogenic causes)
What is a non-tension pneumothorax?
Non-tension pneumothorax:
o Path: non-expanding collection of air around lung, lung collapsed to variable extent
- Pleural cavity pressure equal or less than atmospheric pressure
- air remains in pleural space, NOT exerting pressure across mediastinum
-> contralateral lung unaffected (functional)
What is a tension-pneumothorax?
Tension pneumothorax:
o Path: progressive build-up of air in pleural space -> allows escape into pleural space (but not to return) -> one-way valve effect
- Pleural cavity pressure > atmospheric pressure
-> Pushes against mediastinum -> prevent contralateral lung from fully expanding on inspiration
- AND obstructs venous return to heart -> circulatory instability -> traumatic arrest
Describe the clinical signs of a tension pneumothorax?
- tracheal deviation from side of tension
- hyper-expanded chest
- increased percussion, little movement with respiration
- CVP raised (but low/normal in hypovolaemic states)
- tachycardia
- tachypnoea
- hypoxia
Describe the complications of a pneumothorax?
⇒ Pleural tear acts as one-way valve -> air crosses into pleural cavoty during inspiration -> air trapped in pleural cavity in expiration
⇒ Pleural cavity pressure increases -> affected lung collapses -> respiratory failure (decreased gas exchange, vital capacity, venous return, cardiac output)
⇒ Obstruction of contralateral lung (further impairs gas exchange)
- AND obstructs venous return -> kinks SVC, worsening return, worsening perfusion
⇒ SVC compression -> decreases preload and decreases CO2 -> cardiac failure
⇒ Impaired ventilation and reduced CO2 -> hypotension, hypoxia, obstructive shock -> multi-organ failure -> death
