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Table 2 Compliance to expiratory muscle functional electrical stimulation (FES) sessions and reported adverse events (AE) during the study period

From: Breath-synchronized electrical stimulation of the expiratory muscles in mechanically ventilated patients: a randomized controlled feasibility study and pooled analysis

Treatment compliance Sham (N = 10) Active (N = 10) Total (N = 20)
Total sessions, n 103 169 272
30-min sessions completed, n (% of total sessions) 98 (95.1) 147 (87) 245 (91.1)
Reasons for early stop of current sessiona, % (n/N)    
 Heart rate < 40 bpm 0 (0/103) 0 (0/169) 0 (0/272)
 Heart rate > 130 bpm 1 (1/103) 0.6 (1/169) 0.7 (2/272)
 MAP < 60 mmHg 0 (0/103) 0 (0/169) 0 (0/272)
 MAP > 110 mmHg 1.9 (2/103) 6.5* (11/169) 4.8 (13/272)
 Respiratory rate > 40 breaths/min 1 (1/103) 3 (5/169) 2.2 (6/272)
 SpO2 < 90% 1 (1/103) 0 (0/169) 0.4 (1/272)
 Behavior pain scale > 4 0 (0/103) 0.6 (1/169) 0.4 (1/272)
 Patient request to stop 0 (0/103) 2.4 (4/169) 1.5 (4/272)
 Treatment days from intent-to-treat set, % (median (q1q3)) 100 (69–100) 89 (50–100) 100 (50–100)
Reasons for treatment stop before extubation, patients % (n/N)    
 Discomfort 10 (1/10) 10 (1/10) 10 (2/20)
 Switch to NAVA modeb 10 (1/10) 20 (2/10) 15 (3/20)
 Patient request to stop 0 (0/10) 10 (1/10) 5 (1/20)
Safetyc Event Patient
% (n/N)
Event Patient
% (n/N)
Event Patient
% (n/N)
Adverse events (any) 11 80 (8/10) 17 60 (6/10) 28 70 (14/20)
 Unanticipated adverse device effects 0 0 (0/10) 9 40 (4/10) 9 20 (4/20)
 AEs leading to discontinuation of current FES sessiond or study 8 60 (6/10) 14 50 (5/10) 22 55 (11/20)
 Serious AEs—total 7 60 (6/10) 3 20 (2/10) 10 40 (8/20)
 Serious AEs—deaths 5 50 (5/10) 1 10 (1/10) 6 30 (6/20)
Intervention-related adverse eventse 3 10 (1/10) 13 50 (5/10) 16 30 (6/20)
 Unanticipated adverse device effects 0 0 (0/10) 9 40 (4/10) 9 20 (4/20)
 AEs leading to discontinuation of current FES sessiond or study 3 10 (1/10) 11 50 (5/10) 14 30 (6/20)
 Serious AEs—total 0 0 (0/10) 0 0 (0/10) 0 0 (0/20)
 Serious AEs—deaths 0 0 (0/10) 0 0 (0/10) 0 0 (0/20)
  1. MAP mean arterial pressure, SpO2 oxygen saturation, NAVA neurally adjusted ventilatory assist
  2. *Six of these episodes developed in one patient who already had a high MAP prior to the FES session
  3. aAlso counted as adverse event, see safety parameters
  4. bStimulation artifacts were visible in the diaphragm electrical activity (EAdi) signal, limiting the application of NAVA mode. As the study protocol did not allow to change ventilator mode, expiratory muscle FES sessions were discontinued in patients ventilated in NAVA.
  5. cParticipants that experienced multiple adverse events within a specific category are counted only once in the calculation of occurrence rate for that category
  6. dDiscontinuation of current expiratory muscle FES session based on stop criteria.
  7. eIntervention-related adverse events include definitely, probably and possibly relationships