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.

Alía and Esteban Critical Care 2000 4:72   doi:10.1186/cc660