title: Forced vital capacity and not central chemoreflex predicts maximal hyperoxic breath-hold duration in elite apneists.
abstract: The determining mechanisms of a maximal hyperoxic apnea duration in elite apneists have remained unexplored. We tested the hypothesis that maximal hyperoxic apnea duration in elite apneists is related to forced vital capacity (FVC) but not the central chemoreflex (for CO2). Eleven elite apneists performed a maximal dry static-apnea with prior hyperoxic (100% oxygen) pre-breathing, and a central chemoreflex test via a hyperoxic re-breathing technique (hyperoxic-hypercapnic ventilatory response: HCVR); expressed as the increase in ventilation (pneumotachometry) per increase in arterial CO2tension (PaCO2; radial artery). FVC was assessed using standard spirometry. Maximal apnea duration ranged from 807 to 1262s (mean=1034s). Average HCVR was 2.0±1.2Lmin-1mmHg-1PaCO2. The hyperoxic apnea duration was related to the FVC (r2=0.45, p<0.05), but not the HCVR (r2<0.01, p>0.05). These findings were interpreted to suggest that during a hyperoxic apnea, a larger initial lung volume prolongs the time before reaching intolerable discomfort associated with pending lung squeeze, while CO2sensitivity has little impact.
authors.affiliation: Centre for Heart Lung and Vascular Health, University of British Columbia, Kelowna, BC, Canada; Integrative Vascular Biology Laboratory, Colorado University, Boulder, United States. Electronic address: Anthony.bain@colorado.edu.
authors.forename: Anthony R
authors.initials: AR
authors.lastname: Bain
authors.affiliation: School of Medicine, University of Split, Split, Croatia; Faculty of Medicine, University of Novi Sad, Serbia.
authors.forename: Otto F
authors.initials: OF
authors.lastname: Barak
authors.affiliation: Centre for Heart Lung and Vascular Health, University of British Columbia, Kelowna, BC, Canada.
authors.forename: Ryan L
authors.initials: RL
authors.lastname: Hoiland
authors.affiliation: Faculty of Kinesiology, University of Zagreb, Zagreb, Croatia.
authors.forename: Ivan
authors.initials: I
authors.lastname: Drvis
authors.affiliation: Faculty of Life Sciences and Education, University of South Wales, Glamorgan, United Kingdom.
authors.forename: Damian M
authors.initials: DM
authors.lastname: Bailey
authors.affiliation: School of Medicine, University of Split, Split, Croatia.
authors.forename: Zeljko
authors.initials: Z
authors.lastname: Dujic
authors.affiliation: School of Medicine, University of Split, Split, Croatia.
authors.forename: Tanja
authors.initials: T
authors.lastname: Mijacika
authors.affiliation: Duke University Medical Center, Durham, NC, United States.
authors.forename: Antoinette
authors.initials: A
authors.lastname: Santoro
authors.affiliation: Duke University Medical Center, Durham, NC, United States.
authors.forename: Daniel K
authors.initials: DK
authors.lastname: DeMasi
authors.affiliation: Duke University Medical Center, Durham, NC, United States.
authors.forename: David B
authors.initials: DB
authors.lastname: MacLeod
authors.affiliation: Centre for Heart Lung and Vascular Health, University of British Columbia, Kelowna, BC, Canada.
authors.forename: Philip N
authors.initials: PN
authors.lastname: Ainslie
mesh_terms: D000328:Adult; D001049:Apnea / Q000503:physiopathology; D062485:Breath Holding; D006801:Humans; D018496:Hyperoxia / Q000503:physiopathology; D012018:Reflex / Q000502:physiology; D013147:Spirometry; D013997:Time Factors; D014797:Vital Capacity / Q000502:physiology
keywords: Apnea; Atelectasis; Chemosensitivity; Hypercapnia; Hyperoxia; Lung volume