Adjunctive respiratory therapy

Percussion

Percussion of the chest can aid in secretion clearance. By clapping cupped hands over the thorax in a rhythmic fashion or using mechanical devices that mimic the same action, the pulsating force so generated is transmitted through the thorax to dislodge airway secretions. Used in conjunction with postural drainage, this action often provides an effective method to mobilize secretions from the pulmonary tract.

High-frequency chest compression

High-frequency chest compression (HFCC) enhances mucus clearance. Using an automated vest device worn by the patient that is attached to an air-pulse generator, small volumes of gas are introduced into the vest bladders at a rapid rate that ranges from 5 to 25 Hz, elevating pressures up to 50 cm H ₂ O. This technique, primarily used in cystic fibrosis patients, has efficacy equivalent to conventional chest physiotherapy techniques of percussion and postural drainage. ^, In an observational study comparing HFCC with percussion and postural drainage in nine long-term mechanically ventilated patients, no difference was seen in the amount of sputum production, oxygen saturation, or patient comfort. HFCC was determined to be safe and felt to save staff time. In a small randomized trial of patients extubated after being ventilated for more than 21 days, the addition of HFCC improved sputum clearance but did not have a significant impact on weaning success rates. In a larger randomized trial conducted in a heterogeneous patient population, HFCC was more comfortable than chest physiotherapy, but did not produce a measurable difference in hospital length of stay, resolution of lobar atelectasis, or risk of nosocomial pneumonia. It is difficult to apply this technique to most critically ill patients because of the size of the vest, as covering the thorax may prevent adequate monitoring.

Manual hyperinflation

Manual hyperinflation with an inflation bag aims to inflate the lungs slowly to 1.5–2 times the tidal volume or to peak airway pressures of 40 cm H ₂ O. An inspiratory pause allows for filling of alveoli with slow time constants. This pause is followed by a quick release to allow for rapid deflation. The goals are to recruit atelectatic lung regions, to improve oxygenation, and to improve clearance of airway secretions. Similar to recruitment maneuvers described with mechanical ventilators, manual hyperinflation leads to only transient improvements in oxygenation. Thus it may facilitate secretion clearance but without any identified long-term, clinically significant improvement in patient outcomes. It also has the potential disadvantage of requiring a ventilator disconnect—this method can be mimicked by a mechanical ventilator without doing so.

Contraindications to manual hyperinflation include hemodynamic compromise and elevated intracranial pressure. There is also a risk of barotrauma because of preferential inflation of open lung regions that are highly compliant compared with the collapsed regions.

Mechanical insufflation–exsufflation

Similar to manual hyperinflation, mechanical insufflation–exsufflation can assist in secretion clearance from the peripheral airways. It is commonly used in patients with chronic neuromuscular diseases to augment the cough. For the critically ill patient population, a recent systematic review judged the quality of evidence to be low. A single small clinical trial found reduced chances of extubation failure when used with noninvasive ventilation and manual cough assistance. Insufflation–exsufflation is generally well-tolerated, but side effects include hypotension, nausea, and abdominal distention. In those with respiratory compromise who require positive pressure ventilation, the disconnect or removal of ventilatory support needed to accomplish this intervention may lead to oxygen desaturation and de-recruitment, thereby limiting its use in the intensive care unit (ICU).

Positioning and mobilization

Mobilization of patients in the ICU, either through active or passive limb exercises, may improve overall patient well-being and, in the long term, may lead to better patient outcomes. In one report, the addition of early physiotherapy and occupational therapy to daily interruption of sedation resulted in more ventilator-free days and improved functional capacity.

The now standard default positioning of the patient with the head of the bed elevated to at least 30 degrees from horizontal appears to significantly reduce the risk of aspiration and ventilator-associated pneumonia. Upright positioning of patients in whom there is no contraindication increases resting lung volumes and therefore has benefits for gas exchange and work of breathing, especially among those in whom the supine or semirecumbent position leads to an unusually increased work of breathing. In some individuals with unilateral lung disease, positioning with the affected side up can lead to improved ventilation/perfusion ( $\dot{\text{V}}$ / $\dot{\text{Q}}$ ) matching, in part by increasing perfusion to the dependent “good” side. ^, If atelectasis secondary to retained secretions is the cause, having the affected side up leads to improved drainage of airway secretions.

Postural drainage involves positioning the body to allow gravity to assist in the movement of secretions and is indicated in those rather unusual patients with sputum production volumes of more than 25–30 mL/day and who have difficulty clearing their secretions.

Tracheal suction

Used in conjunction with other techniques to mobilize secretions from the peripheral to the central airways, suctioning is an effective way of removing secretions to improve bronchial hygiene. Using an open method, the patient’s artificial airway is disconnected from the ventilator and a disposable suction catheter is inserted through the tube. A closed system involves a suction catheter within a protective external sheath that is advanced into the trachea while direct connection to the ventilator continues uninterrupted. Because no disconnect is required, the risk of environmental cross-contamination is reduced. Routine changes of the in-line suction catheters are not required, and this restrained practice is cost-effective. ^, Overall, the risk of nosocomial pneumonia between the two systems is not different.

Because of the anatomic arrangement of the large central airways, a suction catheter most often enters the right main bronchus preferentially, as opposed to the left side. Specially designed curved-tipped “left-sided” suction catheters increase the likelihood of their successful navigation into the left mainstem bronchus.

The uncomfortable practice of nasotracheal suctioning has fallen out of favor and should only be considered in spontaneously breathing patients with ineffective or suppressed cough who are able to protect the glottis. It is perhaps most effective when used in conjunction with assisted coughing and other forms of chest physiotherapy.

Complications with suctioning include hypoxemia (especially in the setting of a ventilator disconnect), increased intracranial pressure, mechanical trauma to the trachea, bronchospasm, and bacterial contamination. All patients should be preoxygenated with 100% oxygen for 1 or 2 minutes before suctioning. To reduce the risk of agitation, the patient should be informed before tracheal suctioning is performed. The suctioning should be limited to <15 seconds, and the suction port on the catheter should be opened and closed intermittently—not held closed for longer than 5 seconds at a time.