Chest
Clinical InvestigationsHypercapnic Ventilatory Response in Patients With and Without Obstructive Sleep Apnea: Do Age, Gender, Obesity, and Daytime Paco2 Matter?
Section snippets
Materials and Methods
We reviewed the files of 249 consecutive patients (seen by G.C.M.) who underwent nocturnal polysomnography for suspicion of OSA at the University of Alberta Sleep Center between 1989 and 1994. As part of their workup, all of these patients underwent a daytime HCVR test. In view of the possible interactions between hypnotics and major tranquilizers on ventilatory responsiveness, we excluded 24 patients who were actively taking these medications at the time of their assessment in our clinic. We
Results
Baseline features of subjects with and without OSA are presented in Table 1. OSA was associated with higher BMIs and a higher prevalence of female subjects. Extreme obesity (BMI > 40), however, was uncommon in either group; but among those who had BMI > 40, 7 of the 20 (35%) had OSA by our a priori criteria. Correlates for cHCVR were determined using a linear regression modeling technique, and the results are shown in Table 2. Paco2 was inversely associated with cHCVR, such that a 1-mm Hg
Discussion
We have found that OSA is not independently associated with cHCVR or daytime Paco2. Our results appear to conflict with other studies that have shown an inverse relationship between AHI and HCVR.2, 17, 18 Since many factors influence HCVR, confounding by other variables is an important threat to the validity of results. Airways obstruction, for instance, has been shown to be an independent correlate of daytime hypercapnia among OSA patients.19 Since obstructive airways disease is common20 in
References (29)
- et al.
Decreased hypoxic ventilatory drive in the obesity-hypoventilation syndrome
Am J Med
(1975) - et al.
Chronic CO2 drive in patients with obstructive sleep apnea and effect of CPAP
Respir Physiol
(1995) - et al.
Prediction and reversal of blunted ventilatory responsiveness in patients with hypothyroidism
Am J Med
(1988) - et al.
Hypercapnia in the obstructive sleep apnea syndrome: a re-evaluation of the “Pickwickian Syndrome.”
Chest
(1986) - et al.
The occurrence of sleep-disordered breathing among middle-aged adults
N Engl J Med
(1993) - et al.
Regulation of ventilation in the obstructive sleep apnea syndrome
Am Rev Respir Dis
(1981) - et al.
Progressive improvement of apnea index and ventilatory response to CO2 after tracheostomy in obstructive sleep apnea syndrome
Am Rev Respir Dis
(1982) - et al.
Time course of change in ventilatory response to CO2 with long-term CPAP therapy for obstructive sleep apnea
Am Rev Respir Dis
(1987) - et al.
Sleep apnea pathophysiology: upper airway and control of breathing
- et al.
Mass loading, sleep apnea, and the pathogenesis of obesity hypoventilation
Am Rev Respir Dis
(1982)
Ventilatory pattern at rest and response to hypercapnic stimulation in patients with obstructive sleep apnea syndrome
Respiration
Combined effects of female hormones and metabolic rate on ventilatory drives in women
J Appl Physiol
A manual of standardized terminology, techniques and scoring systems for sleep stages of human subjects
A clinical method for assessing the ventilatory response to carbon dioxide
Australas Ann Med
Cited by (0)
Dr. Sin is supported by a fellowship from the Alberta Heritage Foundation for Medical Research.