title: Real-time dynamic carbon dioxide administration: a novel treatment strategy for stabilization of periodic breathing with potential application to central sleep apnea.
abstract: OBJECTIVE
  This study targeted carbon dioxide (CO(2)) oscillations seen in oscillatory ventilation with dynamic pre-emptive CO(2) administration.
  
  
  BACKGROUND
  Oscillations in end-tidal CO(2) (et-CO(2)) drive the ventilatory oscillations of periodic breathing (PB) and central sleep apnea in heart failure (HF).
  
  
  METHODS
  Seven healthy volunteers simulated PB, while undergoing dynamic CO(2) administration delivered by an automated algorithm at different concentrations and phases within the PB cycle. The algorithm was then tested in 7 patients with HF and PB.
  
  
  RESULTS
  In voluntary PB, the greatest reduction (74%, p < 0.0001) in et-CO(2) oscillations was achieved when dynamic CO(2) was delivered at hyperventilation; when delivered at the opposite phase, the amplitude of et-CO(2) oscillations increased (35%, p = 0.001). In HF patients, oscillations in et-CO(2) were reduced by 43% and ventilatory oscillations by 68% (both p < 0.05). During dynamic CO(2) administration, mean et-CO(2) and ventilation levels remained unchanged. Static CO(2) (2%, constant flow) administration also attenuated spontaneous PB in HF patients (p = 0.02) but increased mean et-CO(2) (p = 0.03) and ventilation (by 45%, p = 0.03).
  
  
  CONCLUSIONS
  Dynamic CO(2) administration, delivered at an appropriate time during PB, can almost eliminate oscillations in et-CO(2) and ventilation. This dynamic approach might be developed to treat central sleep apnea, as well as minimizing undesirable increases in et-CO(2) and ventilation.
authors.affiliation: International Centre for Circulatory Health, St. Mary's Hospital and Imperial College, London, United Kingdom. alberto.giannoni@gmail.com
authors.forename: Alberto
authors.initials: A
authors.lastname: Giannoni
authors.forename: Resham
authors.initials: R
authors.lastname: Baruah
authors.forename: Keith
authors.initials: K
authors.lastname: Willson
authors.forename: Yoseph
authors.initials: Y
authors.lastname: Mebrate
authors.forename: Jamil
authors.initials: J
authors.lastname: Mayet
authors.forename: Michele
authors.initials: M
authors.lastname: Emdin
authors.forename: Alun D
authors.initials: AD
authors.lastname: Hughes
authors.forename: Charlotte H
authors.initials: CH
authors.lastname: Manisty
authors.forename: Darrel P
authors.initials: DP
authors.lastname: Francis
mesh_terms: D000328:Adult; D000368:Aged; D002245:Carbon Dioxide / Q000008:administration & dosage*; D005260:Female; D006333:Heart Failure / Q000150:complications; D006801:Humans; D008297:Male; D056152:Respiratory Rate; D020182:Sleep Apnea, Central / Q000209:etiology / Q000628:therapy*
chemical_list: D002245:Carbon Dioxide