Exploring the use of a non-pharmaceutical method to treat drooling in Parkinson's disease

This study will explore the feasibility of expiratory muscle strength training (EMST), as a novel, non-invasive treatment approach to reduce drooling in people with PD. We hypothesise that EMST will be feasible and well tolerated in this population and will reduce drooling by strengthening the muscles associated with lip closure and swallowing (Pitts et al., 2009; Troche et al., 2010). This study will collect measures related to feasibility of the intervention, as well as swallowing, drooling, and tongue and lip muscle strength before and after a 6 weeks program of high-intensity EMST training. Supervised training will take place twice a week for six weeks with a speech pathologist at Bentley Hospital. Participants will also be prescribed to complete EMST at home on an additional three days each week (unsupervised). Adherence will be monitored during these unsupervised practice sessions by participants keeping a diary of home practice. During each session, EMST will be conducted using a threshold loading device (EMST 150 device: https://emst150.com/), with the initial training load prescribed at 50% of their baseline maximum expiratory pressure. Participants will perform the EMST in sitting, wearing a nose clip. They will be instructed to breathe at their usual rate and depth. An interval-based training approach will be used to optimise the training load that can be tolerated. Specifically, participants will be asked to breathe with a single forced expiration, followed by a 15 second rest. This is repeated 25 times with a one minute rest every five breaths. During each supervised training session, participants will have their arterial oxygen saturation monitored continuously (via a pulse oximeter) and, at the end of each five breath work interval, they will be asked to rate their perceived exertion (using the 0 to 10 Borg category ratio scale). Training loads will be progressed as quickly as possible with the goal of having the load during the final two-minute work interval perceived as ‘very hard’ (7/10 on the Borg scale) with participants unable to consistently maintain lip closure during their expiratory efforts. The aim of this intervention is to strengthen the muscles required for lip closure and swallowing and thus reduce drooling.