The Koga Hospital Center for studies on sleep: status report

Between September 1996 and January 1999 we used polysomnography (PSG) to examine 473 patients (involving a total of 662 records). The diagnosis was a sleep-related breathing disorder in 256 patients, including sleep apnea syndrome (SAS) in 194 patients, sleep hypoxicemia in 18 and insomnia in the other four. The SAS consisted of three subtypes: central apnea (CA) in 56 patients, obstructive apnea (OA) in 124 and mixed apnea (MA) in eight. The ratio of central apnea was relatively higher than the national average. Among the 473 patients, the most common complication was heart disease (133 patients) while other complications included hypertension, and respiratory and cerebrovascular diseases. Concerning the therapy for these patients, continuous positive airway pressure therapy was the most commonly applied and was effective in each type of SAS (CA, OA, MA). Other therapies included prosthetic mandibular advancement, bilevel positive airway pressure, medication and ENT operations. In Koga Hospital, there are many patients with heart disease and/or respiratory disease. We examined those patients who presented with snoring and/or apnea using PSG. Among these patients, SAS was the most common sleep disorder. The relative ratio of CA was high and the average age was higher than those with OA.