Postoperative hypoxia
- Lack of alveolar ventilation
- Hypoventilation (airway obstruction, opiates)
- Bronchospasm
- Pneumothorax
- Arteriovenous shunting (collapse, atelectasis)
- Lack of alveolar perfusion
- Ventilation-perfusion mismatch (pulmonary embolism)
- Impaired cardiac output
- Decreased alveolar diffusion
- Pneumonia
- Pulmonary oedema
Atelectasis
-
Hypoxaemia is often seen during the first 48
hours after most major operations
-
Due to a reduction in functional residual
capacity
-
Significant atelectasis is more often seen
-
The basic mechanisms leading to atelectasis
are:
-
Increased volume of bronchial secretions
-
Increased viscosity of secretions
-
Reduced tidal volume and ability to cough
Clinical features
-
Postoperative pyrexia - usually presenting at
about 48 hours
-
Often accompanied by tachycardia and tachypnoea
-
Examination shows
reduced air entry, dullness on percussion and reduced breath
sounds
-
X-ray shows
consolidation and collapse
Treatment
-
Intensive chest
physiotherapy
-
Nebulised
bronchodilators
-
Antibiotics for
associated infection
Pneumonia
-
Nosocomial pneumonia occurs in 1% of all
patients admitted to hospital
-
Occurs in 15-20% of unventilated ITU patients
-
Occurs in 40-60% of ventilated ITU patients
-
Organisms involved include
-
Gram-negative bacteria (Pseudomonas
aeruginosa, Enterobacter)
-
Staph. aureus
-
Anaerobes
-
Haemophilus influenzae
-
No evidence that prophylactic antibiotics
reduce the risk of pneumonia
Aspiration pneumonitis
-
Aspiration of gastric contents results in a
chemical pneumonitis
-
Most commonly seen in apical segments of right
lower lobe
-
If unrecognised or inadequately treated it can
result in a secondary bacterial infection
-
Secondary infection is usually with
gram-negative and anaerobic organisms
Treatment
-
Tilt table head down and suck out pharynx
-
Consider intubation and endotracheal suction
-
Prophylactic antibiotics should be given
-
No evidence that steroids reduce inflammatory
response
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