Breath-holding and its breakpoint.
Level 5 - mechanism / opinion, no new human data
Narrative review of physiological mechanisms without systematic search methodology
PubMed 16272264 · doi:10.1113/expphysiol.2005.031625
What was done
This narrative review summarizes human physiological studies examining the characteristics of voluntary breath-holding and the potential mechanisms that trigger the involuntary breath at breakpoint.
What was found
The abstract reports no numerical data. It notes that humans cannot voluntarily breath-hold to unconsciousness due to an overriding involuntary mechanism. The breakpoint breath is not solely driven by lung or chest volume changes, blood gas partial pressures, or carotid chemoreceptors, despite breath-hold duration being prolonged by hyperoxia, hypocapnia, and large lung inflations, and shortened by opposite states or higher metabolic rates. Additionally, central respiratory rhythmogenesis continues throughout breath-holding, and duration is prolonged by bilateral phrenic or vagus nerve paralysis, suggesting a potential role for diaphragm muscle chemoreceptors.
Why it matters
It highlights that no single chemical or mechanical factor explains the termination of breath-holding, pointing to a combined role of persistent central respiratory drive and diaphragm-related neural inputs.
Limits
As a narrative review, it lacks a systematic literature search, quality appraisal of included studies, and quantitative synthesis. Specific study designs, sample sizes, and effect magnitudes are not detailed in the abstract.
Cited by
- supports The primary physiological drive that creates the urge to breathe during a breath hold is hypercapnia (elevated CO2) rather than hypoxia.