E2 ModerateWeak / uncertainPEM not requiredCross-SectionalPeer-reviewedReviewed
Hyperventilation and chronic fatigue syndrome.
Saisch, S G, Deale, A, Gardner, W N et al. · The Quarterly journal of medicine · 1994
Quick Summary
Researchers tested whether people with ME/CFS tend to overbreathe (hyperventilate), which could contribute to their fatigue. They measured breathing patterns in 31 patients at rest, during exercise, and after voluntary heavy breathing. Most patients did not show signs of hyperventilation, and those who did usually had other explanations like asthma or panic disorder.
Why It Matters
This study challenges the hypothesis that abnormal breathing patterns drive ME/CFS fatigue, which has implications for treatment approaches. Understanding whether hyperventilation is causal, secondary, or incidental helps clarify ME/CFS pathophysiology and guides clinical management strategies.
Observed Findings
- 71% of ME/CFS patients (22/31) showed no evidence of hyperventilation during any phase of testing.
- Only 4 patients (13%) had unequivocal hyperventilation, three of whom had comorbid panic disorder and one had asthma.
- Five additional patients (16%) showed borderline hyperventilation lasting ≤2 minutes.
- No correlation existed between severity of functional disability and degree of hyperventilation.
- 66% of patients reported symptom onset following an infectious episode.
Inferred Conclusions
- Hyperventilation is not a primary or universal feature of ME/CFS.
- When hyperventilation is present in ME/CFS patients, it is usually attributable to comorbid psychiatric or respiratory conditions rather than being intrinsic to ME/CFS.
- Hyperventilation cannot explain the functional impairment seen across the ME/CFS patient population.
Remaining Questions
- Does hyperventilation develop as a secondary response to chronic illness in a subset of patients, or is it present from illness onset?
- Could subgroups of ME/CFS patients show hyperventilation patterns not captured by this protocol (e.g., during post-exertional malaise)?
What This Study Does Not Prove
This study does not prove hyperventilation never occurs in ME/CFS or that it plays no role in any patient's symptoms; it only shows it is not a universal or primary feature. The cross-sectional design cannot establish causality or longitudinal patterns. Small sample size and the exclusion of patients unable to exercise may introduce selection bias.
Tags
Symptom:Post-Exertional MalaiseFatigue
Biomarker:Blood Biomarker
Phenotype:Infection-Triggered
Method Flag:No ControlsSmall SampleExploratory OnlyWeak Case Definition
Metadata
- PMID
- 8140219
- Review status
- Editor reviewed
- Evidence level
- Single-study or moderate support from human research
- Last updated
- 12 April 2026
About the PEM badge: “PEM required” means post-exertional malaise was an explicit required diagnostic criterion for participant inclusion in this study — not that PEM was studied, observed, or discussed. Studies using criteria that do not require PEM (e.g. Fukuda, Oxford) are tagged “PEM not required”. How the atlas works →
Contribute
Private, reviewed by a human. Not a public comment thread.