Validation of SPECT-CT to assess improvement in airway clearance following expiratory muscle strength training (EMST) to reduce chronic aspiration in patients with head and neck cancer treatment related dysphagia

Background: Videofluoroscopic swallow assessments are subjective and unable to quantify deglutitive aspiration. In this validation study, we assessed whether single-photon emission computed tomography-computed tomography (SPECT-CT) could accurately define aspiration and airway clearance. Additionally, we tested the utility of an 8-week therapeutic period using the expiratory muscle strength training (EMST) device to improve patients’ airway clearance. Methods: A prospective single cohort pilot study was performed in 10 patients with chronic aspiration (DIGEST safety scores 2–4) following head and neck cancer treatment. SPECT-CT was performed after tracer ingestion at baseline (T0), 1 (T1) and 3 (T3) hours following. The EMST device was set at 75% maximum expiratory pressure and patients instructed on a home exercise schedule. Following the 8-week intervention with EMST the SPECT scan was repeated as per the protocol to determine any change in aspiration and airway clearance. Results: Tracer in the lungs and gastrointestinal (GI) tract was quantified with SPECT-CT. At the control assessment, the group mean of aspiration was 3.2% (95% CI: 0.7%, 5.8%) at T0, 2.6% (95% CI: 0.5%, 4.7%) at T1 and 1.9% (95% CI: 0.8%, 3.1%) at T3. Following 8 weeks of EMST treatment the group mean of aspiration was 5.1% (95% CI: 0.1%, 10.0%) at T0, 3.4% (95% CI: 0%, 6.8%) at T1 and 2.6% (95% CI: 0.1%, 5.2%) at T3. The mean airway clearance tended to improve post-EMST, to −1.7 from −0.7 at T1 and to −2.4 from −1.3 at T3 (P=0.08). Conclusions: EMST training resulted in improved maximum expiratory pressures. SPECT-CT was found to be a valid method of quantifying aspiration and feasible in assessment of lung clearance.