Respiratory Compromise in the Surgical Patient – Key Points

Definition: absence of gas from all/part of lung ➔ distal airway collapse
High-risk groups: $\text{elderly}$ , overweight, smokers, pre-existing lung disease
Prevention
• Pre-op deep-breathing exercises
• Intra-op humidification, adequate tidal volumes, avoid high $FiO2$
Key features: cough, chest pain, low $SpO2$ , pleural transudate, late cyanosis/tachycardia
Diagnosis: CXR (WCC/CRP normal unless pneumonia)
Management: intensive physiotherapy (deep breaths, cough), effective analgesia, incentive spirometer, early mobilisation, consider high-flow nasal $O2$

Aetiology: bacterial/chemical (aspiration); hospital-acquired often resistant (MRSA, Pseudomonas, Enterobacter, Serratia)
Aspiration risk ↑ with gastric dilatation/vomiting ⇒ use large-bore NG tube
Symptoms/signs: cough, chest pain, fever, dyspnoea; exam ↓ expansion, bronchial breath/crackles, dull percussion
Diagnostics: CXR, $WCC$ , $CRP$ , sputum & blood cultures
Complication: may trigger ARDS → stiff, fluid-filled lungs ⟹ mechanical ventilation
Severity guide: CURB- $65$
• Confusion
• Urea >7 mmol/L
• RR >30\,\text{min}^{-1}
• SBP $<90$ mmHg / DBP $<60$ mmHg • Age $>65$ yrs
Treatment: follow local antibiotic guidelines; obtain microbiology advice early

Pathology: embolic obstruction beyond right ventricular outflow, usually from DVT
Presentation: dyspnoea, pleuritic pain, cough, haemoptysis, palpitations; signs—hypoxia, tachypnoea, tachycardia
Diagnosis
• CT pulmonary angiography (gold standard)
• ABG: hypoxia, hypocapnia
• ECG: sinus tachycardia ± anterior T-wave inversion
• Echo in unstable pts: right-heart strain
Treatment
• First-line anticoagulation: LMWH ➔ warfarin/NOACs
• Peri-op bleeding risk: use unfractionated heparin infusion (monitor $APTT$ ); rapid reversal by stopping $\approx3$ h or protamine
• LMWH not fully reversible
• Consider IVC filter if anticoagulation contraindicated/high-risk
• Multidisciplinary decision (surgery, haematology, critical care)

Indications: pneumothorax, pleural fluid/haemothorax
Types: Seldinger (effusions/small pneumo) vs traditional large-bore
Size guide: large bore $28{-}30\,\text{F}$ ➔ haemothorax/large or tension pneumo; small $10{-}14\,\text{F}$ ➔ effusions
Key checks: swinging, draining, bubbling, underwater seal
Remove when: effusion to dryness (normal pleural output \approx100{-}150\,\text{ml·day}^{-1}) or lung fully inflated
Ventilated pts (CPAP/NIV) ➔ higher recurrence/tension risk
If pneumothorax present, place central line on same side to avoid bilateral injury