Mechanical insufflation-exsufflation use in neuromuscular disease: A single centre cohort study

Abstract

Mechanical insufflation-exsufflation (MIE) is a standard part of the secretion management package for neuromuscular patients. However, limited data exist on settings, mode of delivery and outcome. We analysed data from an established clinical database of patients started on MIE therapy at our tertiary ventilation centre between 2013-19. 359 adults (66% male; 52±19yrs) were established on MIE. Most common diagnoses were congenital neuromuscular disease (cNMD; 24%), spinal cord injury (SCI; 23%) and amyotrophic lateral sclerosis (ALS; 22%). 69% received MIE via facemask (FM), 31% via tracheostomy. MIE was delivered in manual mode in 44% and automatic mode in 56%. Settings were insufflation (P_ins) 36±6cmH₂O, exsufflation (P_exs) 45±9cmH2O, inspiratory time (T_i) 2.5±0.4s, expiratory time (T_e) 2.6±0.5 and pause 1.8±0.8s. p_exs was higher than p_ins (mean difference 9±6cmH₂O, p<0.001). There were no differences in set pressures between diagnostic groups. P_ins (38±6cmH₂O vs. 35±6cmH₂O, p<0.001) and P_exs (47±9cmH2O vs. 44±9cmH2O, p=0.009) were higher in patients receiving MIE via tracheostomy than FM. p_ins was higher in patients receiving gastrostomy feed (37±6cmH₂O) compared with oral diet (35±6cmH₂O, p=0.033). Overall mortality following initiation of MIE was 46% with time to death of 25±24 months (cNMD 35[17,65]m, SCI 18[7,31]m, ALS 10[4,21]m; log-rank _X²=22.9, p<0.001). These data report the common categories of patients, mode of delivery and outcome of patients receiving MIE therapy. Of clinical relevance, there was no difference in settings between diagnostic groups, with higher exsufflation pressures than insufflation pressures, which was most demonstrable in the tracheostomised patients.