Stability of diurnal blood pressure rhythm during 48-hour ambulatory blood pressure monitoring

Evaluation of nocturnal blood pressure (BP) fall is important for prognosis and selection of antihypertensive therapy. We assessed stability of BP diurnal rhythm in 56 hospitalized hypertensive patients by means of 48-hour ambulatory BP monitoring. According to the degree of congruence of BP fall during two nights of monitoring the following groups of patients were distinguished: with similar diurnal BP rhythm in both nights (72% of all patients, including 42% with sufficient and 30% with insufficient nocturnal BP decline), with different diurnal BP rhythms - with sufficient fall of BP in one night and insufficient in another (28% of all patients). BP variability in all patients did not change and could be considered very stable. Thus when insufficient nocturnal BP fall is detected its stability should be confirmed by repeat BP monitoring.     

Tolerability and efficacy of retard form of indapamide in the treatment of hypertension in elderly patients (results of multicenter open non-comparative trial in Russian program ARGUS)

Open noncomparative multicenter study of tolerability and efficacy of a retard form of indapamide (1.5 mg o.d. for 3 months) in patients older then 55 years was conducted in 14 centers in Russia. Numbers of patients included into was analysis of safety and tolerability were 1277 and 1121, respectively. After 3 months systolic, diastolic and pulse blood pressure (BP) decreased by 20.2, 13.2, 27.5% (supine) and by 19.4, 11.8, 26.9% (standing), respectively. There were no significant changes of heart rate. Effect of treatment was considered positive in 92.4% of patients. Normalization of blood pressure occurred in 51.8% of patients (in 46.2% and 53.4% among men and women, respectively, p=0.0252; in 55.7% and 48% among patients aged <65 and >65 years, respectively). In patients with type II diabetes rates of positive effect and achievement of target BP <130/85 mm Hg were 60.8% and 31.4%, respectively. Hypokaliemia (3.0-3.5 mmol/l) was registered in 43 patients (3.4%), age of 27 of these patients was 65 years. There were no pronounced changes of blood serum levels of creatinine, glucose and uric acid. Significant lowering of atherogeneity cholesterol index occurred in the whole group while both this index and total cholesterol significantly decreased in patients with baseline hypercholesterolemia. Thus in patients older that 55 years monotherapy with retard form of indapamide was demonstrated to be safe and effective antihypertensive intervention.     

Prognostication of man's health status in response to gravity-induced blood shifts based on continuous noninvasive measurement of arterial blood pressure using the Pen'iaz method

Exposure to +Gz acceleration, orthostatic tilt tests and LBNP tests causes distinct blood shifts and deterioration of cerebral circulation. In this case syncope episodes may be prevented by continuous monitoring of circulation parameters, specifically arterial pressure (AP). Our investigations have shown that continuous AP measurement by the Penjaz noninvasive technique may help earlier prediction of the health status in response to gravity-induced blood shifts. In this situation the development of a pre-collapse state is preceded by an emergence of distinct AP waves of the second-third order accompanied by a critical drop of pulse pressure. It is concluded that continuous AP measurement in the finger according to the Penjaz noninvasive technique holds promise as a medical monitoring method in a altered gravitational field.     

+Gx-tolerance by the Cosmonauts of ISS crews 1, 6-9 and visiting crews 1-7 aboard Soyuz vehicles]

Analysis of +Gx tolerance of 15 members of short-term ISS missions and 9 members of long-term ISS missions aboard the Soyuz vehicles showed good tolerance during insertion and satisfactory during descent provided the use of in-flight countermeasures and anti-g suit Kentaur inside the vehicle. Objective data about the tolerance of off-nominal +Gx (6.26 and 8.1 G) pointed to a more pronounced sinus tachycardia and tachypnea in a ballistic descent following long-duration weightlessness as compared with nominal. Physiological deviations were transient, functional by character. Cardiac arrhythmia was largely observed during return to Earth. Two cosmonauts were found to develop prognostically unfavorable ECG indications during off-nominal descent. Main factors in these deviations could be age (above 45) and existence of some individual specifics of cardiac rhythm regulation. These results emphasize the necessity of more careful screening of candidates older than 45 years, as weightlessness may impact their general condition and tolerance of g-loads during return to Earth.     

Shifts in human venous hemodynamics in long-term space flight]

Veins and venous hemodynamics before, during and after long-term space flights (SF) were evaluated with the ultrasonic (B-scan, Doppler) techniques and occlusion plethysmography. Fifteen cosmonauts were investigated in eight SFs of about 6 months in duration. In three SFs, 30 investigations of the main veins in different parts of the body were fulfilled with participation of 7 cosmonauts. In five SFs, 48 investigations of venous distensibility in legs were fulfilled with occlusion plethysmography with participation of 8 cosmonauts. Femoral veins tended to increase distension throughout SF. Exaggerated leg veins distensibility and compliance was persistently observed during application of occlusion from the early period of SF (wks 1-2) which, in our opinion, extenuates the reduction in LBNP tolerance and post-flight degradation of orthostatic stability. These shifts were growing markedly till months 2-3 of exposure to microgravity and tended to stabilize at the worst (as compared with prelaunch values) level at the end of six-month SFs.     

Prediction of cardiac function deviations (ECG data) in the course of permanent cosmonaut's monitoring starting from selection till return to earth after short-duration space flight]

Analyzed were deviations in cardiac function in 29 cosmonauts with previous aviation and other occupations ranging of 29 to 61 y.o. who made 8- to 30-day space flights (totai number of flights = 34) between 1982 and 2006. The deviations were identified in ECG records collected during clinical selection, clinical physiological examination (CPE) before flight, insertion and deorbit in transport vehicles, and post-flight CPE. Based on the analysis, the cosmonauts were distributed into three groups. The first group (55.2% of the cosmonauts) did not exhibit noticeable shifts and unfavorable trends in ECG at any time of the period of observation. The second group (34.5%) showed some deviations during selection and pre-flight CPE that became more apparent in the period of deorbit and were still present in post-flight ECG records. The third group (10.3%) displayed health-threatening deviations in cardiac function during deorbit. These findings give start to important investigations with the purpose to define permissible medical risks and ensuing establishment and perfection of medical criteria for candidates to cosmonauts with certain health problems.     

Achievements and problems of modern trials of antihypertensive drugs

Most important value of lowering of substantially elevated arterial pressure (AP) for improvement of outcomes in patients with arterial hypertension (AH) was convincingly confirmed by large truly placebo controlled randomized clinical trials (RCT) with the use of mainly diuretics, and/or beta-adrenoblockers in the 60-80ths. Later comparative RCT confirmed equal antihypertensive efficacy of 5 main drug classes relative to AP level in brachial artery. In this review we discuss merit of auxiliary class-specific properties of antihypertensive agents potentially affecting prognosis besides AP lowering. We also discuss problems related to decline of significance of quantitative criteria of AH and consideration of AP level in general context of cardiovascular risk; problems of external validity of RCT; extrapolation of RCT results obtained in patients with complicated AH and very high cardiovascular risk on young patients with uncomplicated AH; significance of hard and surrogate end points.     

+Gz load tolerance in nonflight personnel of different ages

Ninety-six healthy nonpilots, aged 21 to 50 years, were exposed to 228 rotations on a 7.25 m arm human centrifuge. The study demonstrated age-related changes in +Gz tolerance of 3 to 5 G (for 30 sec). The subjects at the age 31 to 40 years showed the highest tolerance while the subjects at the age 21 to 25 and 46 to 50 years the lowest tolerance. Young subjects (21-25 years old) often developed an asthenic type of the systolic pressure reaction in the ear lobe and visual disorders whereas older subjects (46-50 years old) displayed cardiac arrhythmias, lower heart rate and delayed recovery of blood pressure after exposure. It was also found that 60-80% subjects aged over 40 well tolerated acceleration of up to 5 G and therefore can be viewed as potential candidates for cosmonauts.