Diagnosing obstructive sleep apnea patients with isolated nocturnal hypoventilation and defining obesity hypoventilation syndrome using new European Respiratory Society classification criteria: an Indian perspective.

BACKGROUND: Recently, new classification criteria for obesity hypoventilation syndrome (OHS) have been described. OHS prevalence according to new criteria has not been reported in obstructive sleep apnea (OSA). Prevalence of OHS has not been previously reported from India. METHODS: Retrospective study was carried out in OSA patients for whom both arterial blood gases (ABG) and end-tidal CO2 (etCO2) records were available. OHS was defined according to old and new criteria. Analysis was carried out among various groups: patients without OHS (Group A), patients with sleep hypoventilation but without daytime hypercapnia (Group B) and patients with daytime hypercapnia (Group C). RESULTS: Out of 367 patients with OSA (body mass index, BMI) 31.9 ± 12.27 kg/m2), finally 128 obese OSA patients were included for analysis. Of those, 15 (5.9%, 95% confidence interval (CI) 3.5-9.4) and 45 patients (17.8%, 95% CI 13.4-22.9) fulfilled prevalence of OHS according to old and new criteria, respectively. Continuous positive airway pressure (CPAP) titration failed in 9.6%, 53.3% and 66.7% in Groups A, B, and C, respectively. For all parameters of OSA severity (apnea-hypopnea index (AHI), Nadir O2, T90) and positive airway pressure (PAP) requirements, patients in Group B were in between those in Groups A and C. Statistically significant difference was seen between Group A and Group B, and between Groups A and C, but not between Groups B and C. CONCLUSION: One in six OSA patients and one in three obese OSA patients (BMI >30 kg/m2) have OHS according to new criteria. Since patients with isolated nocturnal hypoventilation were as sick as patients with daytime hypercapnia, screening for sleep hypoventilation should be carried out in all obese OSA patients.

Pickwickian syndrome, 20 years later.

The Pickwickian Syndrome stimulated new pathophysiological concepts in regard to control of ventilation. With the advent of sleep laboratories, the peculiar sleep apnea occurring in some of these patients has been explained on the basis of intermittent upper airway obstruction. Two patients with different manifestations of the Pickwickian Syndrome are presented. The suggestion is made that these two subsyndromes should have unique designations. The Auchincloss Syndrome is manifested by right heart failure and respiratory acidosis in obese patients who are alert and have no major abnormality of breathing pattern. The fundamental cause of this abnormality is the increased work of breathing caused by the obesity. The cost of breathing is so high that the ventilatory regulation is compromised and respiratory acidosis results. The Gastaut Syndrome is characterized principally by hypersomnia and sleep apnea. The fundamental defect is upper airway obstruction during sleep, resulting in increased work of breathing, which together with the increased work caused by obesity leads to respiratory acidosis and right ventricular failure. Hypersomnia, rather than heart failure or respiratory acidosis, is the major manifestation of this syndrome, and is the result of sleep loss.

Hypersomnia and periodic breathing. Report of a case and review of the literature.

A patient with hypersomnia and periodic breathing has been studied. Both airflow obstruction and an abnormally of the respiratory control mechanism were implicated in the pathogenesis of the ventilatory arrhythmia. It is suggested that the older terms "Pickwick" syndrome and primary alveolar hypoventilation are abandoned for more descriptive terms, e.g. "hypersomnia with periodic breathing".