Conventional 24-h SD of BP is markedly influenced by nocturnal BP fall. The weighted 24-h SD of BP removes the mathematical interference from night-time BP fall and correlates better with end-organ damage, therefore it may be considered as a simple index of 24-h BP variability superior to conventional 24-h SD.

Ambulatory blood pressure increases progressively with increasing altitude, remaining elevated after 3 weeks. An angiotensin receptor blockade maintains blood pressure-lowering efficacy at 3400 m but not at 5400 m.

Abstract-A downward titration of antihypertensive drug regimens in summertime is often performed on the basis of seasonal variations of clinic blood pressure (BP). However, little is known about the actual interaction between outdoor air temperature and the effects of antihypertensive treatment on ambulatory BP. Key Words: blood pressure monitoring, ambulatory Ⅲ hypertension Ⅲ aging S everal studies have reported that blood pressure (BP) values obtained both in the clinic and in ambulatory conditions are lower in hot than in cold months, which is also the case in a general population. 1 In summer, a reduction in cardiovascular mortality has also been observed, 2,3 with a reduction in the occurrence of stroke in hypertensive patients. 4,5 These findings might support the practice of downward titration of antihypertensive drug regimens, especially in the elderly. However, this clinical practice is not embodied in any of the guidelines. 6,7 Moreover, there is limited information regarding the effects of changes in daily mean outdoor air temperature (Ta) on ambulatory BP (ABP) in the elderly, in particular, in aged hypertensive subjects. Finally, no information is available on whether a clinic BP-guided reduction in the dosage of antihypertensive drug, in the case of hot weather, might be responsible for a reduced coverage of BP over 24 hours. The need to clarify these issues is underlined by the observation that older hypertensive patients do not show the same reduction in morbidity and mortality during hot months as younger subjects do. 3 The aim of the present study was, therefore, to more deeply investigate the climate-related changes in clinic and ABP and heart rate in subjects referred to our institutions for BP assessment during a 4-year period. This was done with special attention to the possible interaction between outdoor temperature-related BP changes, aging, and prescription of antihypertensive treatment. Methods

According to the results of the validation study based on the European Society of Hypertension International Protocol the Omron M5-I, R5-I, and HEM-907 may be recommended for clinical use in elderly individuals, without atrial fibrillation or frequent ectopic beats.

SUMMARYHigh-altitude exposure is characterized by the appearance of periodic breathing during sleep. Only limited evidence is available, however, on the presence of gender-related differences in this breathing pattern. In 37 healthy subjects, 23 male and 14 female, we performed nocturnal cardiorespiratory monitoring in the following conditions: (1) sea level; (2) first/ second night at an altitude of 3400 m; (3) first/second night at an altitude of 5400 m and after a 10 day sojourn at 5400 m. At sea level, a normal breathing pattern was observed in all subjects throughout the night. At 3400 m the apnea-hypopnea index was 40.3 AE 33.0 in males (central apneas 77.6%, central hypopneas 22.4%) and 2.4 AE 2.8 in females (central apneas 58.2%, central hypopneas 41.8%; P < 0.01). During the first recording at 5400 m, the apnea-hypopnea index was 87.5 AE 35.7 in males (central apneas 60.0%, central hypopneas 40.0%) and 41.1 AE 44.0 in females (central apneas 73.2%, central hypopneas 26.8%; P < 0.01), again with a higher frequency of central events in males as seen at lower altitude. Similar results were observed after 10 days. With increasing altitude, there was also a progressive reduction in respiratory cycle length during central apneas in males (26.9 AE 3.4 s at 3400 m and 22.6 AE 3.7 s at 5400 m). Females, who displayed a significant number of central apneas only at the highest reached altitude, were characterized by longer cycle length than males at similar altitude (30.1 AE 5.8 s at 5400 m). In conclusion, at high altitude, nocturnal periodic breathing affects males more than females. Females started to present a significant number of central sleep apneas only at the highest reached altitude. After 10 days at 5400 m gender differences in the apnea-hypopnea index similar to those observed after acute exposure were still observed, accompanied by differences in respiratory cycle length. IN TROD UCTI ONPeriodic breathing (PB) is an abnormal ventilatory pattern in which apneas and hypopneas alternate with periods of hyperventilation. Central apneas occur when arterial pCO 2 (paCO 2 ) falls below the threshold required to stimulate breathing, while hyperpnea occurs with reduced arterial pO 2 (paO 2 ), pulmonary congestion or increased chemosensitivity. paO 2 changes represent the most important modulator of peripheral chemoreceptor activity, while 322 ª