Air leak during CPAP titration as a risk factor for central apnea.
OBJECTIVE
Emergence of central sleep apnea has been described in the setting of continuous positive airway pressure (CPAP) initiation. The underlying mechanism is unclear; however, we postulate that air leak washing out anatomical dead space is a contributing factor.


METHODS
Data were obtained from 310 patients with obstructive sleep apnea (OSA) who underwent either split-night or full-night CPAP titration during January to July of 2009. The majority (n = 245) underwent titration with a nasal mask. Average total leak and maximum total leak were measured at therapeutic CPAP level. Unintentional leak was calculated by subtracting manufacturer-defined intentional leak from maximum leak.


RESULTS
SUBJECTS WERE DIVIDED INTO TWO GROUPS: central apnea index (CAI) during titration < 5/hour and ≥ 5/hour. The groups were similar in terms of gender, age, BMI, and AHI. The CAI < 5 group had a median average leak of 45.5 L/min (IQR 20.8 L/min) versus 51.0 L/min (IQR 21.0 L/min) with CAI ≥ 5 (p = 0.056). Maximum leak was 59.5 L/min (IQR 27.0 L/min) with CAI < 5 and 75.0 L/min (IQR 27.8 L/min) with CAI ≥ 5 (p = 0.003). In the subset of subjects titrated using a nasal mask, median average leak was 42.0 L/min (IQR 17.0) in the CAI < 5 group and 50.0 L/min (IQR 16.8) in the CAI ≥ 5 group (p = 0.001). In the CAI < 5 group, median maximum leak was 57.0 L/min (IQR 23.0) versus 74.5 L/min (IQR 24.3) in the CAI ≥ 5 group (p < 0.001).


CONCLUSIONS
Leak during CPAP titration is associated with the development of acute central apnea; these data may have mechanistic and therapeutic implications for complex apnea.


CONCLUSIONS
A commentary on this article appears in this issue on page 1193.
Sleep Disorders Research Program, Brigham and Women's Hospital and Harvard Medical School, Boston, MA ; Pulmonary and Critical Care Unit, Massachusetts General Hospital, Boston, MA.
Sydney B
SB
Montesi
Jessie P
JP
Bakker
Mary
M
Macdonald
Lauren
L
Hueser
Stephen
S
Pittman
David P
DP
White
Atul
A
Malhotra
D045422:Continuous Positive Airway Pressure / Q000295:instrumentation* / Q000379:methods; D004569:Electroencephalography / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D008397:Masks / Q000009:adverse effects*; D008875:Middle Aged; D017286:Polysomnography / Q000379:methods; D012307:Risk Factors; D020182:Sleep Apnea, Central / Q000209:etiology*; D020181:Sleep Apnea, Obstructive / Q000628:therapy*
Sleep apnea; air leak; central apnea