The Feasibility of High-Intensity Interval Training in Patients with Intensive Care Unit-Acquired Weakness Syndrome Following Long-Term Invasive Ventilation

Abstract

Background: Intensive care unit-acquired weakness syndrome (ICUAWS) can be a consequence of long-term mechanical ventilation. Despite recommendations of early patient mobilisation, little is known about the feasibility, safety and benefit of interval training in early rehabilitation facilities (ERF) after long-term invasive ventilation.

Methods and results: We retrospectively analysed two established training protocols of bicycle ergometry in ERF patients after long-term (> 7 days) invasive ventilation (n = 46). Patients conducted moderate continuous (MCT, n = 24, mean age 70.3 ± 10.1 years) or high-intensity interval training (HIIT, n = 22, mean age 63.6 ± 12.6 years). The intensity of training was monitored with the BORG CR10 scale (intense phases ≥ 7/10 and moderate phases ≤ 4/10 points). The primary outcome was improvement (∆-values) of six-minute-walk-test (6 MWT), while the secondary outcomes were improvement of vital capacity (VC_max), forced expiratory volume in 1 s (FEV₁), maximal inspiratory pressure (PI_max) and functional capabilities (functional independence assessment measure, FIM/FAM and Barthel scores) after 3 weeks of training. No adverse events were observed. There was a trend towards a greater improvement of 6 MWT in HIIT than MCT (159.5 ± 64.9 m vs. 120.4 ± 60.4 m; p = .057), despite more days of invasive ventilation (39.6 ± 16.8 days vs. 26.8 ± 16.2 days; p = .009). VC_max (∆0.5l ± 0.6 vs. ∆0.5l ± 0.3; p = .462), FEV₁ (∆0.2l ± 0.3 vs. ∆0.3l ± 0.2; p = .218) PI_max (∆0.8 ± 1.1 kPa vs. ∆0.7 ± 1.3pts; p = .918) and functional status (FIM/FAM: ∆29.0 ± 14.8pts vs. ∆30.9 ± 16.0pts; p = .707; Barthel: ∆28.9 ± 16.0 pts vs. ∆25.0 ± 10.5pts; p = .341) improved in HIIT and MCT.

Conclusions: We demonstrate the feasibility and safety of HIIT in the early rehabilitation of ICUAWS patients. Larger trials are necessary to find adequate dosage of HIIT in ICUAWS patients.

Keywords: Early rehabilitation facility; ICUAWS; MCT vs. HIIT in critically ill patients.

Fig. 1

Increased workload during the HIIT (high-intensity interval training) cycles (10–30 s) over the training period of three weeks. s seconds

Fig. 2

Differences of increase in six-minute walk test [m] between MCT (moderate continuous training) and HIIT (high-intensity interval training) after three weeks of training (box-whisker-plot)

Fig. 3

Mean values (± standard error) of MCT (moderate continuous training) and HIIT (high-intensity interval training) across the fifteen days of exercise. a S_pO_2mean [%] in MCT. b S_pO_2mean [%] in HIIT. c HR_mean [/min] in MCT. d HR_mean [/min] in HIIT. e Mean motivation in MCT [scale from 1 to 10, with 10 representing the highest level of motivation]. f Mean motivation in HIIT [numeric rating scale, NRS, from 1 to 10, with 10 representing the highest level of motivation]. Mean motivation is calculated from the motivation score prior to and post exercise

Fig. 4

Improvement of 6 MWT [m] across duration of (invasive) ventilation [days] of each participant in the MCT (moderate continuous training, n = 24) and HIIT (high-intensity interval training, n = 22) group from t₀ to t₁. Mean improvements of the groups [m] are represented by the blue (MCT) and red (HIIT) horizontal lines