Patient-Ventilator Interaction in Domiciliary Non-invasive Ventilation

    Student thesis: Doctoral ThesisDoctor of Philosophy


    Introduction: Patient-ventilator asynchrony (PVA) can adversely affect the initiation of home mechanical ventilation (HMV). The aim was to quantify the prevalence of PVA during HMV and determine the relationships between PVA and adherence to therapy, respiratory muscle loading, nocturnal gas exchange, health-related quality of life measures and sleep quality.
    Method: A pilot randomised control trial was conducted to compare a physiological led set-up of HMV, using neural respiratory drive to optimise ventilator set-up, to an expert led set-up. Type and frequency of PVA were measured by surface parasternal muscle electromyography, thoraco-abdominal plethysmography and mask pressure during initiation of HMV and 3 months post therapy. Severe PVA was defined as affecting ≥10% of breaths.
    Results: 40 patients (25 male) were enrolled with an age of 58±17years and a body mass index(BMI) of 33±10kg/m2. Underlying diagnoses were neuromuscular ± chest wall disease (NMD-CWD,n=11), obesity-related chronic respiratory failure (ORRF,n=13) and chronic obstructive pulmonary disease (COPD, n=16). Overall, PVA affected 25.6(16.4-35.7)% breaths at initiation of HMV, with ineffective efforts as the predominant type of PVA affecting 10.9(4.6-23.7)% breaths. No difference was observed in the frequency of PVA between physician led and physiological led set-up of HMV at initiation or 3 months(28.4(17.4-37.6)%vs 25.6(14.0-30.4)%;p=0.6 and 22.4(13.3-37.1)%vs23.3(15.2-41.5)%;p=0.7,respectively).
    No correlations were observed between PVA and ventilator adherence(rs=0.02,p=0.90), nocturnal oxygen saturations(rs =0.04,p=0.85), nocturnal carbon dioxide levels(rs=0.15,p=0.41), respiratory muscle unloading(rs=0.06,p= 0.76), patient perception of ventilator synchronisation(rs=0.03,p=0.9) at 3 months of HMV therapy.
    10 patients (7 male) underwent polysomnography assessment of sleep quality. No further correlations were observed between PVA during sleep and sleep efficiency (rs=-0.6,p=0.1), wake after sleep onset(rs=0.5,p= 0.2) or total sleep time(rs=-0.4,p= 0.3) at 3 months of HMV therapy.
    Conclusion: Severe PVA was identified in the majority of patients irrespective of pathophysiological disease. This was not associated with inappropriate delivery of effective ventilation. These data suggest that elimination of PVA may not be required to successfully set-up HMV.
    Date of Award2018
    Original languageEnglish
    Awarding Institution
    • King's College London
    SupervisorAnita Simonds (Supervisor) & Nicholas Hart (Supervisor)

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