Mortality and feasibility of single-limb passive circuit use during home invasive mechanical ventilation: a real-life experience

<bold>Background:</bold> single-limb circuit proved to be effective and largely used in non-invasive ventilation. However, a double-limb circuit is usually preferred in home invasive mechanical ventilation (HIMV) to avoid rebreathing and ineffective airway humidification. Little data on safety of passive single-limb circuits (PSLC) during HIMV in patients with amyotrophic lateral sclerosis (ALS) are available, while still lacking for other conditions. <bold>Aims:</bold> evaluate safety and tolerability of PSLC in HIMV, through the following outcomes at 1 year from tracheostomy: mortality, need for circuit change or other support by the patient or the caregiver. <bold>Methods:</bold> retrospective single-center study including tracheostomized patients (2019-2023) requiring long-term HIMV. <bold>Results:</bold> we collected data from 66 patients affected by: 36 ALS, 4 multiple system atrophy, 5 postoperative and 7 post-stroke complications, 5 muscular dystrophy, 2 miastenia gravis, 2 miopathy, 4 hypoxic encephalopathy, 6 genetic syndromes. Active heated humidified circuit ventilation setting was: 57 pressure-preset volume-guaranteed with volume of 6-8ml/kg predicted body weight, 6 pressure support, 3 pressure controlled. Mean EPAP was 5 cmH2O, mean IPAP min 13 cmH2O and max 22 cmH2O. Cough assistant was prescribed to all patients. Mortality rate at 1 year was 18%, in line with literature. No patient required change in circuit or ventilation mode and none of the caregiver needed additional consultation for the domiciliary care of the PSLC. <bold>Conclusion:</bold> PSLC during HIMV proved to be safe and well tolerated in a mixed group of patients affected by different conditions and generally well accepted by caregivers.