Physiotherapy and airway clearance techniques and devices

Detrimental effects of postural drainage and percussion

Until recently, it was thought, there were no detrimental effects to performing PD&P. As a result PD&P was often over prescribed with the rationale, “lets try it, as it can only help”. However, recent studies have suggested that PD&P may have a detrimental effect on patients. Button et al.⁶ demonstrated that PD&P performed in head down positions may aggravate gastro esophageal reflux in infants with CF. As a result of this study, Button et al.⁷ modified PD positions to no tipping and recently

New evidence to support the use of percussion and vibration in non-tipped positions

As a result of the research concerning the detrimental effects of PD&P, the practice of Physiotherapy in relation to PD&P in Canada has changed. No longer are head-down positions used to assist in secretion removal, rather patients are placed in positions to optimize ventilation to specific lung regions. It has been speculated that the redistribution of ventilation, as occurs with a change in body position, might alter the local airway patency and gas/liquid pump.13, 14 Consequently, it can be

Airway clearance techniques in NICU

For this Paper, eighteen studies were reviewed and summarized. Three systematic reviews could find no evidence to support the routine use of prophylactic airway clearance techniques for neonates. There was some evidence to indicate the need for physiotherapy in neonates with CXR changes and/or mucus plugging.16, 10, 17

There was substantial evidence to support the use of physiotherapy to prevent post-extubation atelectasis and reintubation18, 19 however, physiotherapy needs to be given 2 hourly

Current airway clearance techniques

Over the past 20 years, other airway clearance techniques have been developed which utilize ventilation to get the air behind the secretions and then the expiratory airflow to mobilize the secretions up the airways. These newer techniques have been scientifically validated.²¹

Ventilation

Ventilation may be altered by a variety of methods. The method chosen will depend upon the patient, lung pathology and the level of co-operation from the patient.

Simple positioning in side lying will alter ventilation to a specific lung. Prone positioning will increase PaO2 by as much as 10%, due to enhanced ventilation, although prone positioning is not very practical in the PICU setting. Ventilation will be improved by an inspiratory vital capacity maneuver with a three second breath hold.

Expiratory airflow

The use of the expiratory airflow to mobilize the secretions up the airway has proven to be very effective. Lung volumes, intra-bronchial pressures and pleural pressures are all adjusted to create optimum airflow to mobilize the secretions.

Huffing uses a strong expiratory airflow which compresses the airways and squeezes the mucus up the airways. It is based on the equal pressure point theory. ACBT and PEP both use huffing to mobilize secretions up the airways. Care needs to be taken to avoid

Upper airway secretion clearance

When secretions are mobilized to the upper airways, a strong cough will clear the secretions. If the patient is unable to cough, suctioning may be required in the very ill patient. In patients with a neuromuscular disorder or a spinal cord injury, a coughalator is very effective in clearing secretions from the larger airways.²³

Conclusion

Physiotherapists now have a variety of airway clearance techniques and devices available for use. Applying them to the patient takes expertise not only in knowing the techniques but in understanding the physiology behind the techniques and being able to adapt and apply the techniques to the individual patient. The Physiotherapist also needs to know when airway clearance will be helpful to the patient and when it will have no effect.