Speaking valves (SV) are used infrequently in tracheostomised ICU patients due to concerns regarding their putative effect on lung recruitment. A recent study in cardio-thoracic population demonstrated increased end-expiratory lung volumes during and post SV use without examining if the increase in end-expiratory lung impedance (EELI) resulted in alveolar recruitment or potential hyperinflation in discrete loci.Materials and methods
A secondary analysis of Electrical Impedance Tomography (EIT) data from a previous study was conducted. EELI distribution and tidal variation (TV) were assessed with a previously validated tool. A new tool was used to investigate ventilated surface area (VSA) and regional ventilation delay (RVD) as indicators of alveolar recruitment.Results
The increase in EELI was found to be uniform with significant increase across all lung sections (p < 0.001). TV showed an initial non-significant decrease (p = 0.94) with subsequent increase significantly above baseline (p < 0.001). VSA and RVD showed non-significant changes during and post SV use.Conclusions
These findings indicate that hyperinflation did not occur with SV use, which is supported by previously published data on respiratory parameters. These data along with obvious psychological benefits to patients are encouraging towards safe use of SVs in this critically ill cardio-thoracic patient population.Conclusions
Trial registration: Anna-Liisa Sutt, Australian New Zealand Clinical Trials Registry (ANZCTR). ACTRN: ACTRN12615000589583. 4/6/2015.