Two nap sleep test: an easy objective sleepiness test.

The two nap sleep test (TNST) was developed and its usefulness for detecting sleepiness in long-distance drivers has been reported. This study's authors attempted to apply the TNST as a clinical test of sleepiness. A normal control group (n = 29), an obstructive sleep apnea syndrome (OSAS) group (n = 9), and another sleep disorder group (n = 6) participated. As a result of polysomnography, the sleep latency and sleep time did not differ among the groups. In contrast, the frequency of micro-arousal and movement arousal was significantly higher in the OSAS group than in the other groups. The TNST is thought to be useful for evaluating disturbance of sleep maintenance.

Nasal continuous positive airway pressure changes blood pressure "non-dippers" to "dippers" in patients with obstructive sleep apnea.

To evaluate the circadian pattern of blood pressure (BP) and the effects of nasal continuous positive airway pressure (CPAP) on patients with obstructive sleep apnea (OSA), we examined 24-hour BP in 38 male OSA patients with and without nasal CPAP. We measured the BP at 30-min intervals during daytime (800 to 2200) and nighttime (2200 to 800) hours. A "dipper" was defined as a patient who showed an average reduction of at least 10 mm Hg systolic and 5 mm Hg diastolic between daytime and nighttime values. The subjects were predominantly "non-dipper" (22 of 38 patients, 58%). Daytime hypertension (>160/95 mm Hg) was present in 11 of 38 patients (4 "dippers" and 7 "non-dippers"). After nasal CPAP treatment for 3 days, the average BP decreased significantly during the day and night in all subjects (p<0.05). Fifteen of 22 subjects who were "non-dippers" before treatment reversed to become "dippers." And daytime hypertension was detected in only 5 of these patients during nasal CPAP treatment (4 "dippers" and 1 "non-dipper"). These results showed that the "non-dipper" status was common in patients with OSA, and that nasal CPAP restored the normal circadian "dipper" pattern. We suggest that nasal CPAP may contribute to an improved prognosis in patients with OSA because of a reduction in cardiovascular risk factors in "non-dipper" with severe OSA.

Effects of nasal continuous positive airway pressure on pulmonary haemodynamics and tissue oxygenation in patients with obstructive sleep apnoea.

We investigated the acute effects of nasal continuous positive airway pressure (CPAP) on pulmonary haemodynamics and tissue oxygenation in eight men with obstructive sleep apnoea (OSA) by means of right heart catheterization. They were tested at four dosage levels of nasal CPAP: 0, 5, 10, and 15 cmH2O. Nasal CPAP significantly reduced the cardiac index at the 10 and 15 cmH2O doses. The mean pulmonary artery pressure was significantly elevated with 10 and 15 cmH2O, and pulmonary capillary wedge pressure was significantly increased with 15 cmH2O of nasal CPAP. Pulmonary vascular resistance was significantly increased with 10 cmH2O of nasal CPAP. The 5 cmH2O dose of nasal CPAP did not affect significantly these parameters. Mixed venous oxygen tension was unchanged at any pressure. We conclude that tissue oxygenation was maintained in the OSA patients during administration of nasal CPAP, even though a high CPAP clearly affected pulmonary haemodynamics.

Acute effects of nasal continuous positive airway pressure on 24-hour blood pressure and catecholamines in patients with obstructive sleep apnea.

To assess the acute effects of nasal continuous positive airway pressure (CPAP) on the 24-hour blood pressure and the secretion of catecholamines in urine and plasma, we investigated the changes in the 24-hour blood pressure and urinary and plasma concentrations of epinephrine (E) and norepinephrine (NE) in 26 men with obstructive sleep apnea (OSA) with and without nasal CPAP. Nasal CPAP resulted in significant decreases in the daytime diastolic pressure (from 86 +/-16 mmHg to 83+/-12 mmHg), the nighttime diastolic pressure (from 81+/-12 mmHg to 77+/-9 mmHg) and the nighttime systolic pressures (from 125+/-15 mmHg to 120+/-10 mmHg). There was no significant difference between patients with and without CPAP in the daytime or nighttime urinary E level, but patients who received CPAP showed a significant decrease in daytime urinary NE level (from 156+/-112 microg/14h to 119+/-101 microg/14h) and nighttime urinary NE level (from 143+/-91 microg/10h to 112+/-65 microg/10h). The morning plasma level of NE also decreased (from 371+/-181 pg/ml to 273 +/-148 pg/ml) in patients who received nasal CPAP (p<0.02), but the plasma level of E remained unchanged. There were no correlations between PSG parameters and the reductions in blood pressure and the catecholamine levels induced by nasal CPAP. These findings suggest that OSA contributes, at least in part, to the development of systemic hypertension by increasing sympathetic nervous activity.

[Long-term effects of nasal continuous positive airway pressure on pulmonary function and blood gas data in patients with obstructive sleep apnea syndrome].

To evaluate the long-term effects of nasal continuous positive airway pressure (NCPAP) on pulmonary function and blood gas levels in patients with obstructive sleep apnea syndrome (OSAS), we examined the pulmonary functions and blood gases in 25 male patients with OSAS before and after NCPAP treatment. After 22 months of treatment (titration: 13 cm H2O), no significant changes were observed in the patients' spirograms, pulmonary gas volumes, or diffusion capacity. However, PaO2 levels increased significantly (p < 0.01), from 73.8 mmHg to 79.5 mmHg; PaCO2 levels decreased significantly (p < 0.05), from 45.6 mmHg to 44.2 mmHg; and A-aDO2 levels also decreased significantly (p < 0.05), from 18.7 mmHg to 15.0 mmHg. The patients were divided into a hypoventilated group (PaCO2 > 45 mmHg; 11 cases) and normoventilated group (PaCO2 < or = 45 mmHg; 14 cases). After NCPAP treatment, increased PaO2 and decreased PaCO2 levels were observed in the hypoventilated group, and increased PaO2 and decreased A-aDO2 levels were observed in the normoventilated group. These results suggest that long-term NCPAP treatment improves gas exchange in OSAS patients without influencing the results of pulmonary function tests.

[Non-surgical treatment of obstructive sleep apnea].

We studied the clinical usefulness of nasal continuous positive airway pressure (CPAP) treatment of obstructive sleep apnea syndrome (OSAS). The subject were 56 men with OSAS. Their mean age, apnea index, and SaO2 were 51 +/- 8 years, 48 +/- 18, and SaO2 were 51 +/- 8 years, 48 +/- 18, and 81 +/- 7%, respectively. After titration of CPAP, they underwent nasal CPAP treatment at home every night. Symptoms, blood pressure, pulmonary function, compliance with the prescription and complications of treatment were evaluated every one or two months in an outpatient clinic. Blood pressure decreased significantly from 135 +/- 15 mmHg (systolic) and 88 +/- 14 mmHg (diastolic) to 126 +/- mmHg (systolic) and 78 +/- 6 mmHg (diastolic) in 51 cases after two weeks of treatment. No significant change in pulmonary function except for blood gases was observed after longterm treatment. Excessive daytime sleepiness disappeared and sleep quality improved after treatment in most cases. Thirty-six of 43 patients continued to use nasal CPAP for 34 +/- 16 months and 33% complied with the prescription. Although nasal mask discomfort and dryness of the nose and mouth occurred in several cases, there were no serious complications. These findings suggest that nasal CPAP is useful for treatment of patients with OSAS. However, the problem remains that the cost of nasal CPAP is not reimbursed by the public health insurance system in Japan.

Daytime hypertension and the effects of short-term nasal continuous positive airway pressure treatment in obstructive sleep apnea syndrome.

Daytime blood pressure (BP) in 31 male patients with obstructive sleep apnea syndrome (OSAS) was measured and the effects of nasal continuous positive airway pressure (CPAP) treatment on daytime BP were studied. Subjects were 48 +/- 10 (mean +/- SD) years old and weighed 80 +/- 13 kg. The mean systolic BP and diastolic BP were 135 +/- 15 mmHg and 88 +/- 14 mmHg, respectively and daytime hypertension was present in 12 (38%) subjects. Apnea index (AI) and the lowest oxygen saturation during sleep were significantly more severe in the hypertensive (HT) than in the non-hypertensive (NHT) patients (p < 0.05). AI was significantly correlated with diastolic BP (p < 0.05) and the mean and lowest oxygen saturation during sleep were significantly correlated with both systolic (p < 0.05) and diastolic BP (p < 0.01). After nasal CPAP treatment for two weeks, both systolic and diastolic BP were significantly reduced; the former from 135 +/- 15 mmHg to 126 +/- 10 mmHg (p < 0.005) and the latter from 88 +/- 14 mmHg to 78 +/- 6 mmHg (p < 0.001). These data form direct evidence that daytime hypertension is partially induced by OSAS and is reversible with nasal CPAP treatment.

[Traffic accidents in obstructive sleep apnea patients and effect of nasal CPAP treatment].

We studied the traffic accident rates and daytime sleepiness in obstructive sleep apnea syndrome (OSAS) patient, and evaluated the effectiveness of long-term nasal CPAP treatment. Traffic accidents were observed in 42% of 14 male OSAS patients (46 +/- 7 years old) and near-miss accidents were also observed in 64% during the past three years. Stanford Sleepiness Scale showed 4.7 +/- 1.0, suggesting marked excessive daytime sleepiness (EDS). During NCPAP treatment for 11 +/- 9 months, no traffic and near-miss accidents were reported. After NCPAP treatment, SSS decreased to 2.0 +/- 0.8, and the score of Uchida-Kraeplin test for the evaluation of working ability increased significantly. These results suggest the improvement of EDS and working ability following NCPAP treatment. We conclude that OSAS patients have the tendency of daytime sleepiness and high traffic accidents rates, and NCPAP treatment is effective to improve such problems.

[Improvement of biventricular heart failure in a case of obstructive sleep apnea syndrome by nasal CPAP therapy].

A 42-year-old male patient with obstructive sleep apnea syndrome (OSAS) suffering from biventricular heart failure is reported. He had been treated for OSAS with conventional therapy. However, he complained of severe dyspnea in association with extreme weight gain and general edema. Therefore, he was admitted to our department. He weighed 168 kg on admission, and marked edema was observed. Chest film revealed significant dilatation of the cardiac silhouette and pleural effusion. PaO2 was 37 mmHg and PaCO2 was 66 mmHg. Polysomnography showed an apnea index of 58.3 and severe oxygen desaturation during sleep. Right heart catheterization showed elevation of mean pulmonary artery pressure mPAP: 55 mmHg) and pulmonary capillary wedge pressure (Pcwp: 33 mmHg) suggesting biventricular heart failure. Digitalization and diuretic therapy were immediately initiated. In addition, nasal CPAP was applied to this patient during sleep, and sleep apnea and oxygen desaturation were almost completely reversed. Significant diuresis was observed, and blood gas data and sleep disturbance were improved. Fifty-nine days after admission, his weight had decreased to 96 kg, and mPAP and Pcwp decreased to 32 and 23 mmHg, respectively. This case demonstrates that nasal CPA is an effective tool for the treatment severe OSAS patients.