Submitted on July 7, 2008
Revised on September 30, 2008
Accepted on October 17, 2008
Stability of oxyhemoglobin affinity in patients with obstructive sleep apnea-hypopnea syndrome without daytime hypoxemia
Didier Clause1, Bruno detry1, Daniel O. Rodenstein1, and Giuseppe Liistro1*
1 Université Catholique de Louvain, Cliniques universitaires Saint-Luc
* To whom correspondence should be addressed. E-mail: Giuseppe.Liistro{at}uclouvain.be.
A decrease in hemoglobin affinity for oxygen is considered an adaptative mechanism against tissular hypoxia. Obstructive sleep apnea-hypopnea syndrome (OSAHS) is characterized by recurrent episodes of apnea and hypopnea resulting in arterial oxygen desaturations during sleep. Maillard et al (1991) observed a right-shift of the oxyhemoglobin dissociation curve (ODC) and an increase in 2,3-DPG concentration in 15 patients with severe OSAHS, but some had slight daytime arterial hypoxemia while breathing room air. The aim of our study was to measure the ODC and 2,3-DPG concentrations in a group of subjects normoxemic during daytime referred to our sleep laboratory for suspicion of snoring or OSAHS. The patients were recruited during a period of 6 months. All arterial and venous blood samples were taken early in the morning within 1 hour of awakening following a full-night polysomnography. ODC and 2,3-DPG were analyzed in 88 patients: 56 OSAHS (apnea-hypopnea index (AHI): 27.5 +/- 24.5) and 32 non-OSAHS. We found a significant correlation between the P50 and 2,3-DPG levels in the 88 patients: r= 0.502, p<0.001. We observed no difference between OSAHS and non-OSAHS for the P50 and for [2,3-DPG]. There was no correlation between the severity of OSAHS and either P50 or [2,3-DPG]. Finally, there was no change in these parameters measured at baseline, after 3 days and after 1 month of treatment by nCPAP in 7 OSAHS patients. We conclude that OSAHS patients normoxemic during daytime have comparable oxyhemoglobin affinity than non-apneic subjects.
