Table 3.
Factors that can lead to weaning failure due to the imbalance between ventilatory needs and respiratory capacity
| Factors that increase the load | ||
| Increased resistive loads | Increased chest wall elastic loads | Increased lung elastic loads |
| Bronchospasm | Pleural effusion | Hyperinflation (intrinsic positive end-expiratory pressure) |
| Airway edema, secretions | Pneumothorax | Alveolar oedema |
| Upper airway obstruction | Flail chest | Infection |
| Obstructive sleep apnea | Obesity | Atelectasis |
| Endotracheal tube kinking | Ascites | Interstitial inflammation and/or oedema |
| Secretions encrustation | Abdominal distension | |
| Ventilatory circuit resistance | ||
| Factors that result in decreased neuromuscular competence | ||
| Decreased drive | Muscle weakness | Impaired neuromuscular transmission |
| Drug overdose | Electrolyte derangement | Critical illness polyneuropathy |
| Brain-stem lesion | Malnutrition | Neuromuscular blockers |
| Sleep deprivation | Myopathy | Aminoglycosides |
| Hypothyroidism | Hyperinflation | Guillain-Barré syndrome |
| Starvation/malnutrition | Drugs, corticosteroids | Mysthenia gravis |
| Metabolic alkalosis | Sepsis | Phrenic nerve injury |
| Myotonic dystrophy | Spinal cord lesion | |
*Positive test result is a value of rapid shallowbreathing index (f/VT) lower than 105 or 100; †negative testresult is a value of f/VT higher than 105 or 100.