Short Report| Volume 95, ISSUE 8, P693-696, August 2001

Prevalence of daytime hypercapnia or hypoxia in patients with OSAS and normal lung function

      This paper is only available as a PDF. To read, Please Download here.


      The purpose of this study was to determine factors increasing daytime P aCO2orP aO2in obstructive sleep apnoea syndrome patients (OSAS) with normal pulmonary function tests. Anthropometric, pulmonary function tests, arterial blood gases and sleep polygraphic data were analysed retrospectively in 218 OSAS patients (apnoea–hypopnoea index >15 h−1; 18 females, 55±11 years): 125 patients had abnormal pulmonary function tests, i.e. one or more flow or volume under 80% or above 120% of predictive value (group I) and 93 had normal pulmonary function tests (group II). Hypercapnia was defined as P aCO2≥6·0 kPa and hypoxia asP aO2<9·3 kPa. Patients with abnormal pulmonary function tests were more hypoxic and hypercapnic, more obese, and had a higher apnoea–hypopnoea index (P<0·05). Seventeen patients of group I and four of group II were hypercapnic (13·6% and 4·3%, respectively ). Thirty-one patients in group I (24·8%) had a P aO2<9·3 kPa and six (6·5%) in group II. Stepwise multiple regression analysis showed that in group II, only two factors were correlated with P aCO2: mean apnoea duration and FRC (respectively: c=0·228, P<0·001;c=0·006,P =0·0108); and only two with P aO2: mean apnoea duration: (c=−0·218, P=0·029) and BMI (c=−3·72,P <0·0001). Daytime hypercapnia is present in 4·3% and daytime hypoxia in 6·5% of patients with occlusive sleep apnoea syndrome and normal pulmonary function tests. These alterations in blood gases in OSAS with normal pulmonary function tests should be considered as OSAS severity criteria.




        • Remmers JE
        • Degroot WJ
        • Sauerland EK
        • Anch AM
        Pathogenesis of upper airway occlusion during sleep.
        J Appl Physiol. 1978; 44: 931-938
        • Guilleminault C
        • Tikian A
        • Dement W
        The sleep apnea syndromes.
        Ann Rev Med. 1976; 27: 465-484
        • Chaouat A
        • Weitzemblum E
        • Krieger J
        • Ifoundza T
        • Oswald M
        • Kessler R
        Association of chronic obstructive pulmonary disease and sleep apnea syndrome.
        Am J Respir Crit Care Med. 1995; 151: 82-86
        • Krieger J
        • Sforza E
        • Apprill M
        • Lampert E
        • Weitzenblum E
        • Ratomaharo J
        Pulmonary hypertension, hypoxemia, and hypercapnia in obstructive sleep apnea patients.
        Chest. 1989; 96: 729-737
        • Strohl KP
        • Redline S
        Recognition of obstructive sleep apnea.
        Am J Respir Crit Care Med. 1996; 154: 279-289
        • Stradling JR
        Sleep studies for sleep-related breathing disorders.
        J Sleep Res. 1992; 1: 265-273
        • McNicholas WT
        Diagnostic criteria for the sleep apnoea syndrome: time for consensus.
        Eur Respir J. 1996; 9: 634-635
        • Quanjer PH
        • Tammeling GJ
        • Cotes JE
        • Pedersen OF
        • Peslin R
        • Yernault JC
        Lung volumes and forced ventilatory flows. Report Working Party Standardization of Lung Function Tests, European Community for Steel and Coal. Official Statement of the European Respiratory Society.
        Eur Respir J. 1993; 16: 5-40
        • Lloberes P
        • Montserrat JM
        • Ascaso A
        Comparison of partially attended night time respiratory recordings and full polysomnography in patients with suspected sleep apnoea/hypopnoea syndrome.
        Thorax. 1996; 51: 1043-1047
        • Rapoport DM
        • Norman RG
        • Goldring RM
        CO2homeostasis during periodic breathing: predictions from a computer model.
        J Appl Physiol. 1993; 75: 2302-2309
        • Berger KI
        • Ayappa I
        • Sorkin IB
        • Norman RG
        • Rapoport DM
        • Goldring RM
        CO2homeostasis during periodic breathing in obstructive sleep apnea.
        J Appl Physiol. 2000; 88: 257-264
        • Zwillich CW
        • Sutton DJ
        • Pierson EM
        • Creagh EM
        • Weil JV
        Decreased in hypoxic ventilatory drive in obesity-hypoventilation syndrome.
        Am J Med. 1975; 59: 343-347