Treatment of sleep apnea/hypopnea syndrome(SAHS)requires continuous positive airway pressure (CPAP). Good correlation between respiratory impedance measured by impulse oscillometry (IOS) during sleep and optimal CPAP has been shown by previous studies . The purpose of this study is to evaluate any correlation between central airway resistance (R20), impedance(Z) measured by IOS in awake state and optimal CPAP.
This is a prospective, non- blinded study done in 20 patients (male= 12, female=8, average weight=233 lbs, age=49) diagnosed to have SAHS by overnight polysmnography (PSG) done at Kings County Hospital. The PSG (Sensor Medics, Yorba Linda, CA) and the CPAP titration study was done by certified sleep technicians. The sleep staging and apnea/hypopnea index (AHI) scoring was done manually by a certified physician in sleep medicine according to American Sleep Disorders Association guidelines.Only patients with AHI more than 15 had CPAP titration study. CPAP was generated with a conventional device(BiPAP S/T-D, Respironics Inc, Murrysville, PA)connected to the patient with a tightly fitted nasal mask. Every patient had 3 measurements of R20&Z in a sitting position during normal quiet breathing by the IOS(Jaeger System) in awake state. Average of the 3 values was taken as the final measurement. CPAP titration was done after the IOS measurements, with a starting pressure of 4cm H2o and increased by 2cm H2o for every apnea/hyopnea or by 1 cm H2o for snoring. Regression analysis of the CPAP level and R20&Z values was done.
There is increased central airway resistance and impedance but no corelation was found between optimal CPAP and resting R20 ( c value 0.15) and Z ( c value 0.22).CONCLUSIONS: Normal quiet breathing R20&Z do not predict the optimal CPAP even though there is increased R20&Z.
The relationship between the upper airway anatomy/resistance and sleep apnea is complex.
N.S. Tripuraneni, None.