Standardization of Air Stacking as Lung Expansion Therapy for Patients With Restrictive Lung Disease: A Pilot Study

Although air stacking is a widely used lung expansion therapy essential for restrictive lung diseases, important details such as peak insufflation pressure (PIP) and number of squeezes have not been investigated. The purpose of this study was to standardize a method of air stacking to minimize problems with its application by identifying the optimal pressure and number of squeezes performed by professional physicians and investigating the current status of routine air stacking implementation in patients.

This prospective cross-sectional test-retest study involved individuals who had neuromuscular disorders and had performed air stacking exercise for longer than 1 year. PIP and number of squeezes were measured to identify the differences between caregivers and physicians. Cases of incorrectly performed air stacking were investigated and categorized. The problems associated with air stacking were evaluated.

A total of 45 participants were included. PIP was 41.4 (SD = 4.2; range = 34.8-50.0) cm H2O, and optimal number of squeezes was 3.1 (SD = 0.5; range = 2-4). When the air stacking methods used by caregivers were evaluated, 19 of 45 caregivers (42.2%) used methods inappropriately. Higher PIP and larger number of squeezes were observed with caregiver implementation. Thirty caregivers (66.7%) experienced finger or wrist pain; this problem was observed especially in female caregivers, who tended to incorrectly perform air stacking.

This pilot study showed that the optimal pressure of air stacking was 35 to 50 cm H2O. Caregivers often perform air stacking inappropriately, leading to complications without achieving the purpose of air stacking. The introduction of a new method, such as manometry, can be helpful for achieving optimal air stacking.

Optimal pressure of air stacking can be measured with inexpensive, simple, and commercially available digital manometry. This approach enables air stacking to be performed and taught more accurately and efficiently and reduces complications in both patients and caregivers.