Effect of clonidine on the circulation and vasoactive hormones after aortic surgery.

After completion of abdominal aortic graft, 29 patients received an i.v. infusion of placebo (n = 16) or clonidine 7 micrograms kg-1 (n = 13) over 120 min in a double-blind study.

Aortic surgery: effect of clonidine on intraoperative catecholaminergic and circulatory stability.

Twenty-eight patients presenting for aortic surgery were randomly assigned in a double-blind, placebo-controlled protocol to receive placebo (n = 14) or clonidine (4.7 +/- 1.2 micrograms.

[Effects of histamine on the pressure-volume curve of the respiratory system in the guinea pig].

Intravenous infusion of histamine has been shown to constrict smooth muscle of alveolar ducts. In this study, we have assessed the effects of a prolonged infusion of histamine to obtain a steady state response on quasistatic pressure-volume curves (P-V curves) together with the changes in dynamic compliance (Cdyn) and conductance (G) of the respiratory system. Increasing doses of histamine were given in order to obtain the dose-response characteristics of the changes in Cdyn, G and P-V curves.

A microcomputer-based system for real-time calculation of airway conductance in awake guinea pigs.

Bronchial responsiveness to various drug stimuli is currently studied by constructing cumulative dose-response curves of specific respiratory conductance (SG). Airway conductance can be measured in guinea pigs by the plethysmographic technique, during the rapid transition from expiration to inspiration (TEI). Since the drug action assigns a strict timing to the experiment, conventional methods of measuring SG prove inconvenient and often lack accuracy.

Bronchorelaxation and plasma histamine after salbutamol inhalation.

Plasma histamine in 8 normal subjects was measured before and after inhalation of carbachol to induce a 50% fall in specific airway conductance (SGaw). The measurements were repeated 5 min after inhalation of salbutamol or placebo. No significant change in plasma histamine occurred after placebo or carbachol inhalation, despite the persistent induced bronchospasm after the latter treatment.

Plasma histamine and catecholamines during carbachol-induced bronchoconstriction in normal subjects.

To determine (1) whether changes in plasma histamine occurred during provoked bronchospasm and (2) if so, whether such changes could be related to variations in plasma catecholamines, venous plasma histamine and catecholamines were measured during a dose-response carbachol challenge in eight healthy volunteers. A significant rise in plasma histamine was observed, whereas induced bronchoconstriction was small, 80% +/- 4% of initial specific airway conductance. There was no further increase in plasma histamine, whereas induced bronchoconstriction became more marked (70%, 60%, and 50% of specific airway conductance initial value).

[Use of a severity index in 8 multidisciplinary resuscitation centers].

A universal severity index for acutely ill patients was applied to 794 acute patients treated in eight medical and surgical French intensive care units located in teaching or community hospitals either in Paris or in provincial towns. Measured on the first day in hospital from objective numerical data, the index proved reliable and correlated well with hospital mortality and the sustained therapeutic efforts of the first 24 hours. It could be used in multicentre studies to compare outcomes and evaluate new treatments.

Blood pressure and plasma norepinephrine concentrations after endogenous norepinephrine release by tyramine.

To determine whether small changes in sympathetic activity would cause detectable changes in plasma norepinephrine (NE) levels, and whether the effects of endogenously released and exogenous NE differ, we injected tyramine infusions and l-norepinephrine (l-NE), into six healthy subjects, and the changes in blood pressure (BP) and plasma NE were related. The mean increase in systolic BP was approximately 17 mm Hg with both infusions; diastolic BP increased with l-NE but did not rise significantly with tyramine. Heart rate fell more with l-NE than with tyramine infusions.

Concentration effect relationships of infused histamine in normal volunteers.

Histamine was infused in six normal volunteers at rates of 16, 32, 64 and 96 ng/kg/min increasing at 5-min intervals followed by 128 ng/kg/min for 45 min. Heart rate increased, diastolic blood pressure decreased and skin temperature increased in a dose-dependent fashion. Mean heart rate increased by 15.

Catecholamine neurotransmitters and the heart.

The possible role of adrenaline as a cardiac neurotransmitter was studied following its infusion in 6 healthy volunteers. After the end of the infusion, heart rate remained elevated for several hours despite a rapid fall in plasma adrenaline concentration. Stimulation of sympathetic activity by standing caused a further marked increase in heart rate, which was greater than that found on a control occasion.