The technique of intermittent positive-pressure breathing is used to provide short-term or intermittent mechanical ventilation for the purpose of increasing lung expansion. Intermittent positive-pressure breathing is not the technique of first choice when less invasive therapies can reliably meet clinical objectives. Positive-pressure ventilation can be used with volume- or pressure-limited ventilators.
There are numerous complications: increase in respiratory resistance, alveolar hyperinflation, pneumothorax, nosocomial infection, hypo- or hypercapnia, hypoxia or hyperoxia, aggravation of the ventilation-to-perfusion ratio, epistaxis or hemoptysis, mucus plugs if humidification is poor, gastric distention, and reduction of venous return. In cases of associated bronchospasm, clinical monitoring must be particularly careful. The only absolute contraindication is pneumothorax. However, the indications of intermittent positive-pressure breathing must be assessed more carefully in patients with emphysema, untreated tuberculosis, intracranical hypertension, hemodynamic instability, tracheo-esophageal fistula, recent surgery of the face, mouth, or esophagus, hemoptysis, nausea, regurgitation, and hiccups.
In the ICU, this therapy can be administered every 1 to 6 h. Its efficacy is evaluated as follows: increase of more than 25 per cent in the tidal volume and improvement of cough, chest radiograph, auscultation, and the well being of the patient.
The first indication for intermittent ventilation is for the curative treatment of atelectasis after failure of chest physiotherapy, incentive spirometry, deep breathing exercises, and posturing, or if the patient is not co-operative. The second indication is for prevention of obstruction during limited ventilation or for ineffective cough. It can be interesting to make use of functional respiratory explorations. The third indication is as an alternative to intubation during alveolar hypoventilation.
The therapeutic effects of intermittent positive pressure ventilation do not persist for more than 1 h after the treatment. Fiber-optic bronchoscopy
Fiber-optic bronchoscopy is frequently proposed as an essential element in the treatment of atelectasis and sputum retention. Fiber-optic bronchial aspiration
Fiber-optic bronchial aspiration is used to remove bronchial obstacles. It cannot always be performed, and may be dangerous when there is major hypoxia or hemodynamic instability. The effect of aspiration can be negative if it induces bronchial collapse or suction lesions that aggravate distal retention of secretions.
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