RESUMEN

The effects of celiprolol 200 mg or 400 mg once daily on blood pressure (BP), serum lipids, plasma fibrinogen and airways function was compared with the effects of metoprolol 100 mg or 200 mg once daily in 171 patients with mild to moderate hypertension and coexistent hyperlipidaemia in a double-blind, multicentre study lasting 1 year. Significant decreases in systolic and diastolic blood pressure and heart rate were observed compared with baseline (DBP: celiprolol -13.3 mm Hg, P < 0.0001; metoprolol -14.3 mm Hg, P < 0.0001; SBP: celiprolol -18.2 mm Hg, P < 0.0001; metoprolol -20.5 mm Hg, P < 0.0001; heart rate celiprolol -4 beats/min, P < 0.003; metoprolol -12 beats/min, P < 0.0001). There was no difference between the effects of the two treatments on BP but celiprolol had less effect on heart rate than metoprolol, (celiprolol-metoprolol 7.3 beats/min, P = 0.0002). When compared with baseline values celiprolol significantly reduced serum low density lipoprotein cholesterol (LDL-C) (-5.8%, P = 0.0401) and produced a slight increase in high density lipoprotein cholesterol (HDL-C) which approached statistical significance (4.1%, P = 0.0659). Metoprolol significantly increased serum triglycerides (32%, P = 0.0001) and the total/HDL-C ratio (7.4%, P = 0.0192). Compared with metoprolol, celiprolol significantly reduced LDL-C (-7.3%, P = 0.0062), total cholesterol (-4.5%, P = 0.0085), apoliproprotein B (-10.1%, P = 0.0001), the apolipoprotein B/A1 ratio (-10.9%, P = 0.0001), the total cholesterol/HDL-C ratio (-10.8%, P = 0.0001) and triglycerides (-24.8%, P = 0.0001), and significantly increased HDL-C (6.0%, P = 0.0043).(ABSTRACT TRUNCATED AT 250 WORDS)

Asunto(s)

RESUMEN

Interest in Molecular Sieve Oxygen Generation Systems (MSOGS) for use in military aircraft has demonstrated a need to study physiological effects of MSOGS product gas in the worst case scenario, a rapid decompression (RD). In this paper we report the heart rate (HR) response to positive pressure breathing (PPB) during and after RD from 6,096 to 15,239 m (20,000 to 50,000 ft) in a hypobaric chamber while breathing gas mixtures that simulate the product gas from MSOGS. Interbeat (R-R) intervals were recorded in 10 subjects while they breathed either Aviators' Breathing Oxygen (ABO), that is 99.5% oxygen, or 93% oxygen at two regulator settings: dilution and non-dilution. Additional experimental profiles on six subjects isolated the effects of hypoxia, anxiety, and PPB on HR changes after RD. Anxiety appeared to have the greatest effect. Most of the subjects showed increased HR and reduced HR variability after the onset of pressure breathing (immediately after decompression). As the exposure continued, HR variability increased as the HR began to decline. No consistent change in the HR response could be attributed to the modest increase in hypoxia produced by substitution of 93% oxygen for ABO.

Asunto(s)

RESUMEN

Ultrasonically detected microbubbles were more abundant in the pulmonary artery of dogs intravenously injected with 10 ml of saline than in the same noninjected controls during 10,000 ft (3,048 m), 20,000 ft (6,096 m), and 40,000 ft (12,192 m) exposures. Continuous intravenous (i.v.) drip infusions also introduced many small bubbles. Since they may serve as "nuclei" for visible intravascular bubble formation, are sometimes associated with decompression sickness, and are additionally considered undesirable, it would appear prudent to minimize i.v. injections immediately before flights. However, a 10-min delay before ascent will reduce their number and a 60-min delay will insure their almost complete absence. Also, slow ascent, a 1-h denitrogenation time, or use of a degassed solution will help reduce their total number.

Asunto(s)

RESUMEN

Static performance characteristics of current-inventory USAF oxygen regulators were evaluated with the use of a specialized regulator test stand. Outlet suction pressures, flows, positive pressures, and delivered oxygen dilutions were monitored and recorded as functions of operational altitudes. General findings indicated that: 1) excessive oxygen addition occurs in all models, especially at low cabin altitudes; 2) positive pressure schedules generally conform to specifications; 3) negative suction pressures for most regulators are less than -2.54 cm H2O. The validity of static evaluation is discussed and data interpretation is considered with respect to biomedical compatibility emphasizing maintenance of crewmember physiological sufficiency.

Asunto(s)

RESUMEN

Several oxygen regulators were quantitatively assessed during interface with dynamic respiratory simulation and human user breathing. Continuous measurements of regulator flow, delivered pressure, and delivered oxygenation was provided during variable tidal volumes and breathing frequencies as accomplished initially with breathing simulation and subsequently with human users. The regulators demonstrated large sensitivity to flow demand and the characteristics of the inspiratory flow pulse. Large variations in outlet suction pressure and delivered oxygen concentration accompanied the variable breathing modes of human subjects. The inability of oxygen regulators to consistently provide required oxygen/air delivery is discussed with respect ot inadequate performance specifications currently used.

Asunto(s)

RESUMEN

Growth of Chlorella sorokiniana is unaffected by the choice of atmospheric diluent gas. Reduced total pressure has no inhibitory effect and may be slightly stimulatory.