Low-concentration carbon dioxide is an effective adjunct to positive airway pressure in the treatment of refractory mixed central and obstructive sleep-disordered breathing.
OBJECTIVE
To assess the efficacy of added carbon dioxide as adjunctive therapy to positive airway pressure-refractory mixed obstructive and central sleep-disordered breathing, using a prototype device-the positive airway pressure gas modulator.


METHODS
Open-label evaluation of low concentrations of carbon dioxide added to a positive airway pressure circuit.


METHODS
Physician-attended polysomnographic titration in a free-standing sleep laboratory with end-tidal and transcutaneous carbon-dioxide monitoring.


METHODS
Six adult men (age 54 +/- 5.7 years) with severe poorly controlled mixed sleep-disordered breathing in the absence of renal or heart failure.


METHODS
Flow-independent addition of incremental concentrations of carbon dioxide during sleep.


RESULTS
The respiratory disturbance index before treatment was 66 +/- 14.5 events per hour of sleep, with a nocturnal desaturation low of 84.6% +/- 10.1%. Residual respiratory disturbance index on best treatment was 43 +/- 9 events per hour of sleep. There was an immediate (<1 minute) response to the addition of 0.5% to 1% carbon dioxide, and minimal changes were required to be made across the night. There was no discomfort, shortness of breath, palpitations, headache, or significant increase in respiratory or heart rate. The residual respiratory disturbance index on carbon dioxide, scored irrespective of desaturations, was in the normal range (< 5 / hour of sleep). Two subjects had a second night at the concentration of carbon dioxide determined to be efficacious, with no required concentration change. No adverse effects on overall sleep architecture were noted.


CONCLUSIONS
Low concentrations of carbon dioxide added to conventional positive airway pressure effectively control severe treatment-resistant mixed obstructive and central sleep-disordered breathing.
Thomas
Robert Joseph
RJ
Department of Medicine, Division of Pulmonary, Critcal Care and Sleep Medicine, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA. rthomas1@bidmc.harvard.edu
Daly
Robert W
RW
Weiss
J Woodrow
JW
D001785:Blood Gas Monitoring, Transcutaneous; D015992:Body Mass Index; D002245:Carbon Dioxide / Q000008:administration & dosage / Q000097:blood / Q000627:therapeutic use*; D006706:Homeostasis; D006801:Humans; D008297:Male; D008875:Middle Aged; D017286:Polysomnography; D011175:Positive-Pressure Respiration / Q000295:instrumentation / Q000379:methods*; D012720:Severity of Illness Index; D020181:Sleep Apnea, Obstructive / Q000175:diagnosis / Q000188:drug therapy / Q000628:therapy*
D002245:Carbon Dioxide