When the patient continues to deteriorate or fails to improve with other measures and oxygen therapy, he needs some respiratory support with mechanical ventilation. Mechanical ventilation improves C02 elimination (confirmed by performing ABG Test) and removes work of breathing, gives relief from exhaustion by giving rest to the respiratory muscles.
Types of Mechanical Ventilation:Mechanical ventilation may be non-invasive or invasive.
1. Non- invasive mechanical ventilation
In non- invasive respiration is supported with face mask or nasal mask so that, endotracheal intubation is avoided. Patient should be conscious, cooperative, be able to breath spontaneously and cough effectively. This technique is commonly used in acute exacerbation of COPD and pneumonia.
2. Invasive mechanical ventilation
In invasive mechanical ventilation endotracheal tube is passed. Patient may require full or partial support. In full Support all respiration is controlled by ventilator that does not allow spontaneous breaths. Patient is deeply sedated with short acting IV anesthetic agent and paralyzed with muscle relaxant. In partial support ventilator helps and augment patient’s own breaths; it does not require deep sedation and paralysis.
Indications of Mechanical VentilationIndications of mechanical ventilation are listed below
- Respiratory failure not responding to medical treatment.
- Head injury - controlled hyperventilation to reduce intracranial pressure.
- Chest injury.
- Severe pulmonary edema
Weaning from Respiratory Support:This is the process of progressively reducing and eventually removing all external ventilatory support and associated apparatus. If apparatus is suddenly removed, patient may be unable to breath because of respiratory muscle weakness and residual decreased lung compliance.
Complications of Mechanical Ventilation:
- Tube in one lung causes collapse of other lung.
- Fall in cardiac output due to positive pressure in lung and thorax that reduces venous return.
- Ventilator induced lung injury such as barotraumas due to over-distension of alveoli leading to pneumomediastinum, subcutaneous emphysema and pneumothorax.
- Nosocomial (hospital acquired) pneumonia.
- Abdominal distension and ileus.
Modes of Mechanical VentilationNON-INVASIVE RESPIRATORY SUPPORT
| ||Used in acute exacerbation of COPD, pulmonary edema and post- operative collapse of lung. May be used with endotracheal intubation or tightly fitting face mask|
| ||Used in acute exacerbation of COPD|
|INVASIVE RESPIRATORY SUPPORT|
| ||Appropriate for initial control of patient with little respiratory drive|
| ||IT allows patient to breath spontaneously between the mandatory tidal volumes delivered by ventilator.|
| ||Spontaneous breaths are augmented by a pre- set level of positive pressure (positive pressure means above atmospheric pressure)|
| ||Pressure given throughout the expiration. Helps in re- expand collapse or edematous lung.|