Itsuro Miyazato

Changes of Circulating Atrial Natriuretic Peptide and Antidiuretic Hormone in Obstructive Sleep Apnea Syndrome

Patients with obstructive sleep apnea (OSA) syndrome are known to exhibit nocturnal natriuresis/diuresis. We studied plasma and urinary levels of atrial natriuretic peptide (ANP), a potent natriuretic hormone released from the heart, and plasma antidiuretic hormone (ADH) levels in patients with OSA during awake and sleeping periods, to compare with those of normal subjects. Seven patients with OSA and 6 normal subjects were studied. Arterial blood samples were drawn during the awake and the sleeping period, while in patients with OSA, blood samples were obtained during the apneic period. Urine samples were collected over two 12-hour periods (9 a.m.-9 p.m. and 9 p.m.-9 a.m.) In patients with OSA, plasma ANP as well as urinary ANP excretion increased during the apneic period compared with the awake period. There was a significant negative correlation between plasma levels of ANP and ADH in patients with OSA. On the other hand, normal subjects had no apparent differences in plasma and urinary ANP levels between the two periods. It is suggested that nocturnal increase in ANP and decrease in ADH are responsible for the nocturnal diuresis and natriuresis associated with OSA.

Ratings of perceived exertion in chronic obstructive pulmonary disease--a possible indicator for exercise training in patients with this disease.

SummaryThe purpose of this study was to evaluate the usefulness of ratings of perceived exertion (RPE) as an indicator of exercise intensity in patients with chronic obstructive pulmonary disease (COPD). The subjects were ten male patients with COPD, whose mean forced expiratory volume in 1 s was 1.091, SD 0.41, and ten healthy middle-aged men. Ramp incremental exercise on a cycle-ergometer was performed and RPE was determined by the Borg 15-point scale. The absolute oxygen uptake at each RPE was significantly greater in the healthy subjects than in the patients with COPD. However, oxygen uptake calculated as a percentage of maximal at any RPE did not differ significantly between the two groups. Arterial blood lactate concentration at points 15 to 19 on the RPE scale was increased in healthy subjects (P<0.05–P<0.001), while the dyspnoea index at points 11 to 19 on the RPE scale was higher in patients with COPD (P<0.05–P<0.001). The main complaints on stopping exercise were dyspnoea in the patients with COPD and fatigue in the healthy subjects. Although the nature of RPE may have been different in the two groups, RPE could be a possible indicator of exercise intensity when physicians prescribe exercise to patients with COPD.