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Biomedical subjects

G Baccelli

Publications and source records attributed to G Baccelli.

At least 19 recordsLinked to original sources
PubMed1995

Scintigraphic recording of blood volume shifts.

UNLABELLED: A scintigraphic device consisting of small scintillation probes tightly fixed to the skin was developed to record intravascular blood volume shifts continuously and simultaneously at several sites. The aim of the present study was to ascertain the reliability of the measurements obtained, show the blood shifts induced by common daily activities in healthy subjects and clarify the mechanisms responsible for hemodynamic changes. METHODS: Measurements were made in three fields of the right lung, the liver, thighs and calves of 16 men during Valsalva maneuver, hyperventilation, various posture changes and treadmill walking. Some tests were repeated. RESULTS: The measured blood volume shifts were always in the expected direction and in accordance with those reported in the literature; they also were reproducible. Therefore, the measurements were reliable. A pattern of blood volume changes peculiar to some common daily activities was recorded in subjects moving freely. Insights were obtained on the mechanisms responsible for the blood volume shifts. CONCLUSION: Our noninvasive technique provides reliable continuous measurements of blood volume changes at several sites during common daily activities and could be applied not only in healthy subjects but also in patients.

Activities of Daily Living↗
PubMed1993

Simultaneous recording of blood volume shifts in different vascular beds in man by a versatile scintigraphic method.

A device was developed to record the blood volume changes occurring in the lung and calf during postural changes, physical exercise, and the Valsalva maneuver in man. The changes in regional counting rates from the right middle lung and the calf mirrored the well-known changes in venous return that are expected to occur in response to the above-mentioned external stimuli. Thus a sustained decrease in lung blood volume was noted on assumption of the erect posture as well as during the forced expiration of the Valsalva maneuver. In addition a rapid increase and a sharp decrease in lung blood volume took place at the very onset and at the very end of walking, respectively. The calf blood volume declined immediately at the onset of walking, increased slightly in the ensuing two minutes, and returned to baseline quickly at the termination of walking. The authors' method enables real-time equilibrium blood pool scintigraphy to be recorded continuously and simultaneously from different districts over sustained periods of time irrespective of the posture and the physical activity performed by the patient. Their method might improve knowledge of the systemic circulatory responses to selective physiologic and therapeutic interventions in health and disease.

Blood Volume↗
PubMed1992

A new method for evaluating lung uptake of thallium-201 during stress myocardial scintigraphy.

A novel, multipurpose device has been designed that allows thallium activity to be continuously studied from a given lung area at rest and at peak exercise. The information gained from this technique proves to be relevant and reliable because lung thallium activity is displayed in real time and the interpretation of thallium distribution is not based on qualitative or quantitative comparison with that in the myocardium or mediastinum. The time-activity curves obtained in our study group are reported and the relation of peak activity to plateau activity (peak/plateau ratio) is proposed as an index that is easy to obtain for identifying patients with normal and impaired left ventricular function.

Adult↗
PubMed1985

Carotid sinus reflexes during postural changes, naturally elicited fighting behaviour, and phases of sleep in the cat.

Reflex responses of mean blood pressure and of heart rate to either bilateral common carotid occlusion (CO) or unilateral carotid sinus dilatation (CSD) during rest and different behaviours have been compared in conscious cats. Unloading and loading the carotid sinus receptors elicited equal reflex responses both of mean blood pressure and of heart rate during control immobile behaviour (CO: +34 +/- 6 mmHg and +35 +/- 6 beats . min-1; CSD: -37 +/- 4 mmHg and -52 +/- 11 beats . min-1), standing on the hindlimbs (CO: +36 +/- 5 mmHg and +29 +/- 5 5 beats . min-1; CSD: -40 +/- 6 mmHg and -61 +/- 10 beats . min-1), fighting against an attacking animal (CO: +34 +/- 5 mmHg and +31 +/- 5 beats . min-1; CSD: -37 +/- 5 mmHg and -56 +/- 10 beats . min-1), quiet wakefulness (CO: +37 +/- 5 mmHg and +38 +/- 4 beats . min-1; CSD: -34 +/- 4 mmHg and -53 +/- 8 beats . min-1) and synchronised sleep (CO: +36 +/- 5 mmHg and +37 +/- 4 beats . min-1; CSD: -36 +/- 4 mmHg and -52 +/- 6 beats . min-1). Desynchronised sleep was associated with an identical response to CSD (-30 +/- 4 mmHg and -51 +/- 7 beats . min-1) but with a reduced (p less than 0.01) reflex response to CO (+18 +/- 3 mmHg These data indicate that carotid sinus baroreflexes largely maintain their ability to modulate pressure upwards and downwards when blood pressure has been reset at somewhat higher levels by standing and fighting and at somewhat lower levels by synchronised sleep. The selective depression of carotid occlusion responses during desynchronised sleep suggests a central or peripheral shift of the baroreflex stimulus-response curve or a selective central inhibition of the reflex response to baroreceptor unloading.

Animals↗
PubMed1985

Hemodynamic factors changing blood flow velocity waveform and profile in normal human brachial artery.

We have investigated the influence of changes of perfusion pressure and local peripheral resistance on blood flow velocity waveform and profile in normal human peripheral arteries. Blood flow velocity and profile were recorded from the distal end of the left brachial artery in ten normal subjects by means of an ultrasonic device. The records were obtained in basal conditions and after blood pressure in the brachial artery and local peripheral vascular resistance were changed, separately or together, by progressive inflation of two arm cuffs, one encircling the proximal half of the left arm and the other the middle part of the left forearm. Both blood flow velocity waveform and profile were shown to be markedly modified by changes in perfusion pressure and local peripheral vascular resistance. Reduction of perfusion pressure decreased both forward and reverse peak velocities, but had the largest effect upon reverse velocity. The upslope and the downslope of the forward velocity wave were left unchanged. Increase in local peripheral vascular resistance markedly augmented reverse peak velocity, whether perfusion pressure was normal or reduced. Increased resistance only slightly influenced peak forward velocity.

Arm↗
PubMed1985

A non-invasive index of leg arterial perfusion pressure during walking, derived from cutaneous toe temperature.

This article describes and evaluates a non-invasive technique for continuous monitoring of hemodynamic changes in the legs during walking. The method involves monitoring of cutaneous toe temperature. In six normal subjects we have shown that, during exercise under carefully controlled conditions, a unique steady-state toe temperature exists for any given leg arterial perfusion pressure, when perfusion pressure is varied by means of an external occluding ankle cuff. Further, we have demonstrated a strong correlation between this external ankle cuff pressure and the time rate of changes of toe temperature during the test-period following occlusion. Correlation coefficients, r1, were between -1 and -0.88 (mean -0.95; standard deviation +/- 0.03) for big toe and between -1 and -0.87 (mean -0.94; standard deviation +/- 0.03) for third toe. We conclude that during walking the time profile of toe temperature changes is a useful index of changes in leg perfusion pressure. Therefore, toe temperature may be used to study the dynamics of leg arterial circulation in atherosclerotic occlusive diseases.

Adult↗
PubMed1981

Role of sinoaortic reflexes in hemodynamic patterns of natural defense behaviors in the cat.

To evaluate whether sinoaortic afferents contribute to the hemodynamic pattern of fighting, cardiovascular changes associated with fighting were studied in cats before and after sinoaortic denervation. Sinoaortic denervation exaggerates the decrease in heart rate, cardiac output, and arterial pressure during immobile confrontation (hissing, staring but no movement). During nonsupportive fighting (fighting with forelimbs while lying on one side) and supportive fighting ( fighting while standing on four feet) sinoaortic denervation reduces the increase in heart rate and cardiac output, minimizes the mesenteric vasoconstriction, induces a fall in arterial blood pressure, but does not affect iliac vasoconstriction or vasodilatation. The hemodynamic pattern of fighting is similarly changed by temporary inactivation of carotid sinus baroreflexes by common carotid occlusion as by chronic section of sinoaortic nerves. It is concluded that sinoaortic reflexes play an important role in the cardiovascular patterns accompanying natural fighting. They favor cardiac action and allow a marked visceral vasoconstriction to occur, thus minimizing or preventing a fall in blood pressure during emotional behavior.

Aggression↗
PubMed1979

Cardiovascular changes during spontaneous micturition in conscious cats.

The hemodynamic changes occurring during spontaneous micturition were recorded in conscious cats. Arterial blood pressure was continuously measured by chronically implanted arterial catheter, heart rate (HR) by a cardiotachometer, and cardiac output (CO), superior mesenteric (MF), renal (RF), and external iliac blood flows (IF) by chronically implanted electromagnetic flow probes. Spontaneous micturition was accompanied by little change in mean arterial pressure (-9.7 +/- 0.7%), but by a marked decrease in HR (-49.0 +/- 1.2%) and CO (-28.6 +/- 2.5%), and therefore by a marked decrease in total peripheral conductance (-21.0 +/- 3.5%). Visceral and hindlimb blood flows were markedly reduced during micturition (MF, -34.7 +/- 2.1%; RF, -22.6 +/- 1.5%; and IF, -48.7 +/- 1.5%, respectively) due to a marked reduction in regional conductances in both these areas. The vasomotor changes in the regional circulations were prevented by local sympathectomy. Thus spontaneous micturition is associated with marked changes in cardiac function and systemic circulation. Cardiac output is decreased, but diffuse nervous systemic vasoconstriction compensates for this and provides maintenance of arterial blood pressure level.

Animals↗
PubMed1978

Control of regional circulations by the sino-aortic reflexes during desynchronised sleep in the cat.

In the intact cat desynchronised sleep induces arterial hypotension and mesenteric vasodilatation, whereas in limb muscles vasoconstriction occurs because of the concurrent action of a spinal vasoconstriction reflex. After sino-aortic denervation arterial hypotension is exaggerated and mesenteric vasodilatation is greater, while the muscular bed of the limbs also becomes vasodilated rather than constricted. It is concluded that during desynchronised sleep the sino-aortic afferents act to check a central influence inhibiting vasoconstrictor tone both in the viscera and muscles: thus an excessive fall in blood pressure is prevented by avoiding a too large visceral vasodilatation and by unmasking the vasoconstrictor action of the spinal reflex in the limbs.

Animals↗
PubMed1976

Interplay of sino-aortic reflexes and haemodynamic changes during natural sleep in the cat.

1. When the sino-aortic afferents are intact, desynchronized sleep causes a small decrease in the blood pressure, a vasodilation in the mesenteric and renal beds, and a vasoconstriction in the external iliac bed. 2. After sino-aortic deafferentation desynchronized sleep causes a larger fall in the blood pressure, a greater vasodilatation in the mesenteric and renal beds, and a vasodilatation replaces the vasoconstriction in the external iliac bed. 3. The sino-aortic reflexes play an active role in controlling circulation during desynchronized sleep by opposing the centrally induced reduction in adrenergic sympathetic tone. This effect of sino-aortic reflexes is similar on both visceral and muscular vessels. In addition, the muscular bed, but not the visceral one, is regulated by a spinal reflex vasoconstriction mechanism which is apparent only when the sino-aortic reflexes are intact.

Animals↗
PubMed1976

Interactions between sino-aortic reflexes and cardiovascular effects of sleep and emotional behavior in the cat.

The role of sino-aortic reflexes in the control of circulation during normal behavior was investigated by comparing cardiovascular reactions during various but reproducible types of behavior before and after bilateral sino-aortic deafferentation. Chronic deafferentation caused little change in baseline blood pressure, but a subtler, important role of sino-aortic reflexes was revealed by examining the integrated cardiovascular responses to behavioral stimuli. During desynchronized sleep, the buffering action of sino-aortic reflexes prevented a marked and diffuse vasodilation, with an action that was particularly evident on muscle blood vessels. During emotional behavior, especially when emotion was accompanied by movement, sino-aortic reflexes opposed the consequences of muscle vasodilation by inducing tachycardia and vasoconstriction in the viscera and in noncontracting muscles. A reciprocal type of interaction between behavior and sino-aortic reflexes was shown by testing the amplitude of the carotid occlusion response before and during desynchronized sleep; the latter condition was consistently associated with decreased effectiveness of the reflex response. The possibility is considered that this might indicate central suppression of the carotid sinus reflex during desynchronized sleep and that a similar inhibitory interference might occur during emotional behavior. Alternatively, reduction of the reflex response might result from a shift of the stimulus-response curve on either side of its steep portion.

Animals↗