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Results for “CONSCIOUSNESS”

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At least 55 records · Page 3Linked to original sources

PubMed1991

Cardiovascular effects of elgodipine in conscious pigs with a normal coronary circulation and in conscious pigs with a healed myocardial infarction.

The cardiovascular effects of the phenyldihydropyridine derivative elgodipine (0.3, 1, 3, 10, and 30 microgram/kg/min) were studied in normal conscious pigs and in pigs with chronic left ventricular dysfunction (LVD, caused by coronary artery occlusion) without and after beta-adrenoceptor blockade with propranolol (0.5 mg/kg + 0.5 mg/kg/h). In normal pigs, elgodipine increased cardiac output from 2.57 +/- 0.09 to 5.21 +/- 0.24 L/min (p less than 0.05) as a result of a doubling of the heart rate. Mean arterial blood pressure decreased from 94 +/- 2 to 76 +/- 3 mm Hg (p less than 0.05) as a result of a decrease in systemic vascular resistance. Left ventricular (LV) dP/dtmax increased (by up to 78 +/- 9%), but left ventricular end-diastolic pressure (LVEDP) remained unchanged. After propranolol administration elgodipine did not increase LV dP/dtmax, and the increase in heart rate was attenuated, resulting in a smaller increase in cardiac output (from 2.11 +/- 0.13 to 3.09 +/- 0.23 L/min, p less than 0.05), but an unchanged vasodilator response. In pigs with LVD, elgodipine increased cardiac output and LV dP/dtmax less than in normal animals, but the vasodilator response was not affected. LVEDP decreased from 14.6 +/- 1.6 to 11.7 +/- 2.5 mm Hg (p less than 0.05). In animals with LVD, propranolol caused a more severe depression of systemic hemodynamics, but did not modify the cardiovascular responses to elgodipine. Its cardiovascular profile suggests that elgodipine may not only be useful in the treatment of cardiovascular disorders for which other dihydropyridines are already in use, but also in mild chronic heart failure.

Adrenergic beta-Antagonists↗

PubMed1999

[Time of consciousness, consciousness of time].

Time shapes our behavior: we must estimate the duration of events in our environment in order to anticipate changes and time our activity in function of these changes. However, there is no sensory modality devoted to the perception of time, therefore the question is to know which mechanisms underlie the consciousness that time flows and allow us to estimate time precisely. This article proposes a brief overview of psychological, neuropsychological and brain imaging studies which rely on theoretical models postulating the existence of an internal timer. These studies examine the different components--time base, counter and memory--of this timer: particularly they are aimed at characterising the relationships between the evolution of these components with age or their pathological alterations and changes in temporal judgements. They also attempt to specify the neural bases of these components. From this brief overview comes the idea that, if an internal timer exits, it does not mark objective time but a multitude of subjective times.

Biological Clocks↗

PubMed2001

Consciousness, the brain, and spacetime geometry: an addendum. Some new developments on the Orch OR model for consciousness.

Brain action is both physically controlled and beyond computational simulation. Accordingly, there is a strong case for examining brain organization in a way that specifically seeks out structures in the brain that might plausibly support such putative non-computational action at the ill-understood borderline between quantum and classical physics. Thus, we must seek out structures in the brain where the actual physics that operates at this level could plausibly have important influence on brain action. This is the basis of the Orch-OR model that Stuart Hameroff and I have been proposing, and which he describes in the foregoing article. The case is strongly put forward that the neuronal microtubules play a key role in the required quantum/classical borderline activities which might have an essential relevance to the phenomenon of consciousness. The exploration of such deeper level of neuronal structure and function is very much a continuation of the line of work so wonderfully initiated by Cajal.

Brain↗

PubMed1993

[Conscious, unconscious and not conscious in coma].

In this work, the relation between the consciousness and the unconsciousness was studied in patients presenting a neurosurgical coma state. The study includes 29 patients with clinical observations during their hospitalisation period and a follow up for one year after the emergence from the state of coma. The psychoanalytic methods were used, taking in consideration the emotional and personal history of each patient. We attempted to demonstrate the persistence of the unconscious psychic life during coma and the early period after awakening from the coma. In addition, we felt the existence of a sort of direct confrontation with the unconscious psychic life in some patients emerging from a comatose state. The question is also what are the effects of such experience and how would they affect the life of the patients in the future?

Coma↗

PubMedDate not supplied

Reversal of central benzodiazepine effects by intravenous flumazenil after conscious sedation with midazolam and opioids: a multicenter clinical study. The Flumazenil in Intravenous Conscious Sedation with Midazolam Multicenter Study Group II.

The efficacy and safety of flumazenil in antagonizing the central effects of the benzodiazepine midazolam was demonstrated in patients in whom conscious sedation was induced with midazolam plus an opioid (fentanyl, meperidine, or morphine). In a double-blind, multicenter study, 240 patients were administered flumazenil postoperatively at an average intravenous dose of 0.7 mg (7 ml) and 114 patients were administered an average dose of 9 ml placebo. Complete reversal of sedation was observed in 80% of flumazenil-treated patients and 30% of placebo-treated patients 5 minutes posttreatment. In 87% of patients who responded to flumazenil, the level of alertness was maintained throughout the 180-minute observation period. Midazolam-impaired psychomotor performance returned to normal 5 minutes posttreatment in 80% of the flumazenil-treated patients and 28% of the placebo-treated patients. Flumazenil was less effective in reversing midazolam-induced amnesia, with only 70% of flumazenil-treated patients (and 15% of placebo-treated patients) able to recall the picture shown them at the 5-minute assessment, and fewer patients able to recall pictures shown at later times. Flumazenil was well tolerated, although adverse effects were reported slightly more often than in the placebo group. The most frequent adverse events in both groups were dizziness and nausea. Vital signs were not affected.

Adolescent↗

PubMedDate not supplied

Reversal of central benzodiazepine effects by flumazenil after intravenous conscious sedation with diazepam and opioids: report of a double-blind multicenter study. The Flumazenil in Intravenous Conscious Sedation with Diazepam Multicenter Study Group II.

The efficacy and safety of a new benzodiazepine antagonist, flumazenil, were assessed in a double-blind multicenter study. Flumazenil (mean dose, 0.76 mg) or placebo (mean dose, 8.9 ml) was administered intravenously to 130 and 67 patients, respectively, who had been given diazepam in conjunction with an opioid (fentanyl, meperidine, or morphine) for the induction and maintenance of intravenous conscious sedation for diagnostic or therapeutic surgical procedures. The group assessable for efficacy comprised 122 patients treated with flumazenil and 64 patients given placebo. After 5 minutes, 80/115 (70%) flumazenil-treated patients, compared with 21/63 (33%) placebo-treated patients, were completely awake and alert, as indicated by a score of 5 on the Observer's Assessment of Alertness/Sedation Scale. Ninety-five percent of patients in each group who attained a score of 5 at the 5-minute assessment showed no loss of alertness throughout the 180-minute assessment period. Flumazenil-treated patients also performed significantly better on the Finger-to-Nose Test and the recall of pictures shown at the 5-minute assessment. Flumazenil was well tolerated, with no serious adverse effects reported. Thirty-nine (30%) of flumazenil-treated patients, compared with 17 (25%) of placebo-treated patients had one or more drug-related adverse experiences. The most common adverse effects were nausea and vomiting in the flumazenil group and nausea and injection-site pain in the placebo group. Flumazenil was found to promptly reverse sedation induced by diazepam in the presence of opioids.

Adolescent↗

PubMed1979

The action of angiotensin II on the baroreflex response of the conscious ewe and the conscious fetus.

1. In conscious non-pregnant and pregnant ewes and in chronic fetal lamb preparations, the beat by beat relationship between pulse interval and systolic pressure was studied during acute elevations in arterial pressure induced by phenylephrine. Baroreflex sensitivity, which was defined as the slope of the pressure-pulse interval relationship when phenylephrine was used to raise pressure, was abolished by atropine and increased by propranolol. Baroreflex sensitivity was less in pregnant ewes and in foetal lambs compared with non-pregnant ewes. 2. These findings suggest that the vagus nerve is responsible for the reflex bradycardia that occurs in the foetus and the ewe when arterial pressure is increased. 3. In both fetal and adult sheep, actue hypertension due to I.V. injection of angiotensin II was not associated with a consistent and progressive bradycardia, such as was seen with acute hypertension caused by phenylephrine. Angiotensin II has no direct chronotropic effect on heart rate in either the adult or the fetus. 4. No linear relationship between arterial pressure and pulse interval was seen when angiotensin II was used to raise pressure in sheep which were treated with propranolol. Therefore the lack of cardiac slowing with pressor doses of angiotensin II was not due to concomitant activation of the sympathoadrenal system. 5. It is concluded that in both fetal and adult sheep angiotensin II reduces the increase in vagal tone which is responsible for slowing of heart rate in response to acute rises in arterial pressure.

Angiotensin II↗

PubMed1959