The influence of varying inspired fractions of O 2 and CO 2 on the development of involuntary breathing movements during maximal apnoea

Toni Breskovic, Mihajlo Lojpur, Petra Zubin Maslov, Troy J. Cross, Jasenka Kraljevic, Marko Ljubkovic, Jasna Marinovic, Vladimir Ivancev, Bruce D. Johnson, Zeljko Dujic

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


The growing urge to breathe that occurs during breath-holding results in development of involuntary breathing movements (IBMs). The present study determined whether IBMs are initiated at critical levels of hypercapnia and/or hypoxia during maximal apnoea. Arterial blood gasses at the onset of IBM were monitored during maximal voluntary breath-holds. Eleven healthy men performed breath holds after breathing air, hyperoxic-normocapnia, hypoxic-normocapnia, and normoxic-hypercapnia. Pre-breathing of the gas mixtures facilitated the IBM onset, reducing the time-to-onset for ∼46% (hyperoxic condition) and for ∼80% (hypoxic condition) compared to the normoxic air breathing time. A strong correlation (R=0.83, P=0.002) between arterial partial pressure of CO 2 (PaCO2) at IBM onset after pre-breathing hyperoxic and hypercapnic gas mixtures was observed, suggesting the existence of a possible IBM PaCO2 threshold level of ∼6.5±0.5kPa. No clear "threshold" was observed for partial pressure of arterial O 2 (PaO2). However, we observed that IBM onset was influenced, in part, by an interaction between PaO2 and PaCO2 levels during maximal apnoea. This study demonstrated the complex interaction between arterial blood-gases and the physiological response to maximal breath holding.

Original languageEnglish (US)
Pages (from-to)228-233
Number of pages6
JournalRespiratory Physiology and Neurobiology
Issue number2
StatePublished - Apr 30 2012


  • Apnoea
  • Diaphragm
  • Respiratory muscles
  • Ventilatory control

ASJC Scopus subject areas

  • Neuroscience(all)
  • Physiology
  • Pulmonary and Respiratory Medicine

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