TL;DR: ⚪ Definitive null — early in-bed cycle ergometry added to usual physiotherapy did not improve physical function after ICU discharge, despite protocolized, well-documented delivery.
1. Publication
- Title: Early In-Bed Cycle Ergometry in Mechanically Ventilated Patients (CYCLE)
- Acronym: CYCLE
- Year & Journal: NEJM Evidence, published June 25, 2024 (3(7):EVIDoa2400137)
- Citation: Kho ME, Berney S, Pastva AM, et al. NEJM Evid. 2024;3(7):EVIDoa2400137. doi:10.1056/EVIDoa2400137
2. Context & Rationale
Background: Critical illness requiring mechanical ventilation causes important, long-lasting (5-8 year) physical function impairment. Enhanced mobilization strategies, including in-bed cycle ergometry, have been proposed to mitigate ICU-acquired weakness, following a promising CYCLE pilot trial.
Research Question/Hypothesis: In mechanically ventilated adult ICU patients, does early in-bed cycle ergometry added to usual physiotherapy improve physical function at 3 days post-ICU-discharge compared with usual physiotherapy alone?
3. Design & Methods
- Study Type: International, multicenter RCT (Canadian Critical Care Trials Group)
- Population: 360 adult ICU patients undergoing invasive mechanical ventilation; enrolled Nov 2016–May 2023
- Intervention: 30 minutes of early in-bed cycling plus usual physiotherapy (n=178), started within first 4 days of MV, continued until marching in place x2 days, ICU discharge, or 28 days
- Comparator: Usual physiotherapy alone (n=182)
- Statistical Power & Follow-Up: Primary: Physical Function ICU Test-scored (PFIT-s), 0-10 scale, at 3 days post-ICU-discharge.
4. Key Results
360 patients randomized; cycling began median 2 days into MV, median 3 sessions, mean 27.2±6.6 min each.
Outcome | Cycling + Usual PT | Usual PT Alone | Notes |
PFIT-s at 3 days post-ICU-discharge (primary) | No significant benefit | — | Clear null result |
5. Internal Validity Assessment
Large (360-patient), international, multicenter RCT with confirmed intervention delivery (early initiation, multiple sessions delivered as protocolized). Overall: Strong — clean null result following a promising pilot signal; independent commentary titled this "Cycling in ICU — Keep Pedaling or Push the Brakes?" reflecting the definitive, if disappointing, nature of this confirmatory result.
6. External Validity Assessment
International (Canadian-led) multicenter mechanically ventilated ICU population — broadly representative of general ICU populations eligible for early mobilization.
7. Strengths & Limitations
Strengths: Rigorous confirmatory trial following a well-conducted pilot; standardized, protocolized intervention delivery with documented adherence (timing, session count, duration).
Limitations: As with many ICU rehabilitation trials, usual-care physiotherapy already incorporated some mobilization, potentially narrowing the achievable contrast between arms; a broader systematic review/meta-analysis (59 RCTs, n=8462) found enhanced mobilization activities overall may still reduce ICU-acquired weakness, delirium duration, and MV duration — suggesting cycling specifically (rather than mobilization broadly) may not be the most effective modality.
8. Interpretation & Practice Impact
Does not support routine addition of early in-bed cycle ergometry to usual physiotherapy for improving physical function after ICU discharge — a definitive null result for this specific modality, though broader enhanced-mobilization approaches may still hold value per the wider evidence base.
9. Controversies & Subsequent Evidence
An accompanying NEJM Evidence editorial ("Cycling in ICU — Keep Peddling or Push the Brakes?") engages directly with how to interpret this null result against the backdrop of continued enthusiasm for ICU-based rehabilitation technology. A broader systematic review/meta-analysis of 59 RCTs (n=8462) on enhanced mobilization found reductions in ICU-acquired weakness (RR 0.79), delirium duration (MD -1.34 days), and MV duration (MD -1.07 days) — suggesting the null CYCLE result may be specific to cycle ergometry as a modality rather than enhanced mobilization broadly.
10. Summary & Executive Takeaway
Summary: CYCLE randomized 360 mechanically ventilated ICU patients across multiple international centers to early in-bed cycle ergometry plus usual physiotherapy or usual physiotherapy alone. Physical function (PFIT-s) at 3 days post-ICU-discharge showed no significant benefit from added cycling, despite protocolized, well-documented intervention delivery.
Overall Takeaway: Early in-bed cycle ergometry does not improve physical function after ICU discharge when added to usual physiotherapy — a definitive negative result for this specific rehabilitation modality, though broader enhanced-mobilization strategies (per meta-analytic evidence) may still offer benefit through other mechanisms or intensity levels.
11. Bibliography
- Kho ME, Molloy AJ, Clarke F, et al. CYCLE pilot trial. BMJ Open. 2016;6(4):e011659.
- Heels-Ansdell D, Kelly L, O'Grady HK, et al. CYCLE statistical analysis plan. JMIR Res Protoc. 2024;13:e54451.