The recent systematic review by Paulus and colleagues provides an insight into manual lung hyperinflation (MHI) , but deserves further comment.
MHI research has generally focused on surrogate measures of secretion clearance, such as lung/thorax compliance . Investigation into the effect of MHI on airway secretion clearance is warranted to elucidate the mechanistic and hence potential therapeutic role.
Volpe and colleagues  and Li Bassi and colleagues  have reported mechanical ventilation flow-bias thresholds that can move airway secretions both towards (expel) and away (embed) from the mechanical ventilator. These measurement methods may be useful to identify the optimal MHI technique . Van Aswegen and colleagues recently demonstrated that MHI with a positive end-expiratory pressure of 7.5 cmH2O in a supine position resulted in a preferential airflow distribution (using technetium-99m) to the right lung as compared with the left lung . Hence, for left lung collapse the combination of patient positioning (for example, lying on the right side) with MHI may both optimise lung recruitment and/or secretion clearance.
Owing to the requirement for airway disconnection, Paulus and colleagues allude to the potential for MHI to result in airway contamination and cause ventilator-associated pneumonia . Along similar lines, however, closed suction has often been advocated as a means to prevent ventilator-associated pneumonia (also by preventing circuit disconnection). A recent meta-analysis on closed versus open suction demonstrated no changes in the rates of ventilator-associated pneumonia , but closed suction was associated with increased duration of mechanical ventilation and airway contamination. The optimal MHI technique and outcome measures require identification.
MHI: manual lung hyperinflation.
The author declares that they have no competing interests.
Anaesth Intensive Care 2000, 28:255-261. PubMed Abstract
Li Bassi G, Saucedo L, Marti JD, Rigol M, Esperatti M, Luque N, Ferrer M, Gabarrus A, Fernandez L, Kolobow T, Torres A: Effects of duty cycle and positive end-expiratory pressure on mucus clearance during mechanical ventilation.
Van Aswegen H, Van Aswegen A, Du Raan H, Du Toit R, Spruyt M, Nel R, Maleka M: Airflow distribution with manual hyperinflation as assessed through gamma camera imaging: a crossover randomised trial. [http://dx.doi.org/10.1016/j.physio.2012.05.007] webcite