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At least 127 records · Page 7Linked to original sources

PubMed2006

Conscious level in children with diabetic ketoacidosis is related to severity of acidosis and not to blood glucose concentration.

OBJECTIVE: To ascertain whether initial depression of conscious level in children with diabetic ketoacidosis (DKA) is related to hyperosmolality, acidosis or other factors. METHODS: In 225 episodes of DKA without evidence of cerebral edema, we examined the relationship between conscious level and initial biochemical variables. We contrasted these findings with those in 42 children who later developed cerebral oedema. RESULTS: On admission, 42/225 (19%) had mild (pH 7.26-7.35); 96 (44%) moderate (pH 7.11-7.25); and 80 (37%) severe DKA (pH <or= 7.10). Conscious level: alert and oriented (group 1, n=123), drowsy but oriented when woken (group 2, n=62), semi-conscious or confused/agitated (group 3, n=9), comatose (group 4, n=4). Glasgow Coma Score (GCS) was available in 65. pH varied significantly with conscious level; group 1, 7.20+/- 0.11(mean+/- SD); group 2, 7.10+/- 0.16; group 3, 6.96+/- 0.11; group 4, 6.88+/- 0.09 (anova, p<0.001). Blood glucose (BG) was not different between the groups. GCS was related to pH (r(s) = 0.49, p < 0.001), but not to BG or electrolyte levels. Age, sex, plasma sodium, corrected sodium and osmolality also varied with conscious level in a univariate model. Using multivariate analysis comparing groups 1 with groups 2-4, lower pH and younger age were the only independent determinants of impaired conscious level (p<0.001, p=0.036). Conscious level in the children with cerebral edema was also closely related to pH and not to other biochemical variables. pH was lower at each conscious level in the children with later cerebral edema. CONCLUSIONS: In children with DKA, initial conscious level is closely related to pH and weakly to age, but not to BG or plasma sodium level. Thus cerebral function in DKA is related to severity of acidosis even when there is no evidence of cerebral edema.

Adolescent↗

PubMed2000

Cardiovascular and sympathetic effects of L-glutamate and glycine injected into the rostral ventrolateral medulla of conscious rats.

The aim of the present study was to examine the effects of L-glutamate and glycine microinjected into the rostral ventrolateral medulla (RVLM) in conscious unrestrained rats. Microinjection of 2 nmol of L-glutamate increased the mean arterial pressure (MAP) and renal sympathetic nerve activity (RSNA) in the conscious rats. The RSNA responses were significantly larger in the conscious rats than in anesthetized rats, while the magnitude of the pressor responses was similar in conscious and urethane-anesthetized rats. L-Glutamate injection significantly decreased heart rate in the conscious rats, whereas it increased the heart rate slightly but not significantly in the anesthetized rats. Microinjection of 100 nmol of glycine into the RVLM of conscious rat decreased MAP and RSNA. In 2 of the 6 rats examined, the depressor and sympathoinhibitory responses were preceded by a few seconds of a pressor and sympathoexcitatory phase. The decreases of RSNA in response to glycine injection were significantly larger in the conscious rats than in the anesthetized rats, whereas the magnitude of the depressor responses was similar in the two groups of rats. Heart rate decreased in response to glycine injection into the RVLM in the conscious and the anesthetized rats. In conclusion, in conscious unrestrained rats, as well as in urethane-anesthetized rats, L-glutamate acts as a sympathoexcitatory agent and glycine acts as a sympathoinhibitory agent in the RVLM. The sympathetic responses to these amino acids are larger in conscious rats than in anesthetized rats.

Anesthesia, General↗

PubMed2005

Individual effect-site concentrations of propofol are similar at loss of consciousness and at awakening.

Reported effect-site concentrations of propofol at loss of consciousness and recovery of consciousness vary widely. Thus, no single concentration based on a population average will prove optimal for individual patients. We therefore tested the hypothesis that individual propofol effect-site concentrations at loss and return of consciousness are similar. Propofol effect-site concentrations at loss and recovery of consciousness were estimated with a target-control infusion system in 20 adults. Propofol effect-site concentrations were gradually increased until the volunteers lost consciousness (no response to verbal stimuli); unconsciousness was maintained for 15 min, and the volunteers were then awakened. This protocol was repeated three times in each volunteer. Our major outcomes were the concentration producing unconsciousness and the relationship between the estimated effect-site concentrations at loss and recovery of consciousness. The target effect-site propofol concentration was 2.0 +/- 0.9 at loss of consciousness and 1.8 +/- 0.7 at return of consciousness (P <0.001). The average difference between individual effect-site concentrations at return and loss of consciousness was only 0.17 +/- 0.32 microg/mL (95% confidence interval for the difference 0.09-0.25 microg/mL). Our results thus suggest that individual titration to loss of consciousness is an alternative to dosing propofol on the basis of average population requirements.

Adult↗

PubMed1991

[Consciousness and the electroencephalogram].

In the course of 12 years the authors subjected to clinical EEG and stereo-EEG (SEEG) 72 patients (66 epileptics with the diagnosis of psychomotor epilepsy and grand mal) and six psychotic patients suffering from schizophrenia. With the exception of five epileptics and two psychotic patients all subjects had epileptic foci in the amygdalohippocampal complex (AHK). After coagulation of these foci marked improvement of the fits and the mental state occurred in half the patients. During EEG and SEEG recording the authors used different activation methods (hyperventilation through the nose and mouth, sleep, listening to music) and above all direct electric stimulation (ES) of one of the AHK. Secondary epileptic foci had, as a rule, more spikes and a lower threshold for ES than primary ones which contained more delta and slow theta waves. The ES led as a rule to an emotional response, such as anxiety and fear, more rarely to illusions, depersonalization and oneiroid hallucinations and twice to a hedonic response of non-sexual character. The purpose of ES was to assess the site from where it is possible to start the original aura or typical parox. The authors considered these foci, consistent with data in the literature, as the leading focus and it was subsequently coagulated. The authors investigated the reactivity and vigility by the patient's response to sound (the patient had to press a button) and by an interview with the patient. It was revealed that in isolated discharges of the spikes and waves in the scalp electrodes, i.e. in the neocortex, reactivity is lacking. In isolated discharges in the AHK the reactivity was satisfactory, but as a rule anxiety developed. It is thus possible to divide consciousness into emotional consciousness with its site in the AHK, i.e. in the limbic system, and rational consciousness which is a function of the neocrotical system. Congenital changes of consciousness such as vigility or sleep are described as "states" of consciousness. The rational or emotional aspect of behaviour is described as "type" of consciousness. Under normal conditions the states of consciousness alternate periodically and are sharply defined, the types of consciousness are closely linked and are difficult to separate. Under pathological conditions the "states" of consciousness differ less markedly and the "types" of consciousness are in dissociation. Thus obnubilation, depersonalization, illusions, pathic affects etc. develop, as a rule as part of the epileptiform or psychotiform syndrome.

Adolescent↗

PubMed1983

Treatment of children with posttraumatic transient loss of consciousness.

Recommendations for the treatment of asymptomatic children who have had a brief period of loss of consciousness due to blunt head trauma are anecdotal and vary greatly. The purpose of this study is to define the range of practice in treating children with uncomplicated loss of consciousness by determining: (1) the frequency of "routine" hospitalization for observation and (2) those criteria which, when present, result in hospitalization. A total of 957 pediatricians representing five groups of physicians responded to a nationwide questionnaire survey to determine current treatment practices for uncomplicated loss of consciousness. Of all directors of pediatric emergency rooms and pediatric chief residents, 44% routinely hospitalize all patients who have had loss of consciousness. Academic child neurologists and child neurologists in private practice hospitalize these patients least frequently, 29% and 31%, respectively (P less than 0.05). Of pediatricians in private practice, 38% admit all children with loss of consciousness. Pediatricians from all groups who do not routinely hospitalize all children with uncomplicated loss of consciousness showed similarity in the criteria they use for admission. These variables include: abnormal vital signs (97% to 100%), skull fracture (96% to 100%), suspicion of child abuse (93% to 100%), observation of a change in level of consciousness (92% to 99%), unreliable caretaker at home (91% to 98%), vomiting (90% to 99%), history of a change in level of consciousness (88% to 100%), duration of loss of consciousness (88% to 96%), seizure (77% to 94%), age of child (62% to 75%), child nearly back to normal (32% to 48%), dizziness (22% to 49%), witness of loss of consciousness not reliable (24% to 36%), headache (9% to 16%), and decision deferred to neurosurgeon (2% to 7%).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed2003

New evidence of animal consciousness.

This paper reviews evidence that increases the probability that many animals experience at least simple levels of consciousness. First, the search for neural correlates of consciousness has not found any consciousness-producing structure or process that is limited to human brains. Second, appropriate responses to novel challenges for which the animal has not been prepared by genetic programming or previous experience provide suggestive evidence of animal consciousness because such versatility is most effectively organized by conscious thinking. For example, certain types of classical conditioning require awareness of the learned contingency in human subjects, suggesting comparable awareness in similarly conditioned animals. Other significant examples of versatile behavior suggestive of conscious thinking are scrub jays that exhibit all the objective attributes of episodic memory, evidence that monkeys sometimes know what they know, creative tool-making by crows, and recent interpretation of goal-directed behavior of rats as requiring simple nonreflexive consciousness. Third, animal communication often reports subjective experiences. Apes have demonstrated increased ability to use gestures or keyboard symbols to make requests and answer questions; and parrots have refined their ability to use the imitation of human words to ask for things they want and answer moderately complex questions. New data have demonstrated increased flexibility in the gestural communication of swarming honey bees that leads to vitally important group decisions as to which cavity a swarm should select as its new home. Although no single piece of evidence provides absolute proof of consciousness, this accumulation of strongly suggestive evidence increases significantly the likelihood that some animals experience at least simple conscious thoughts and feelings. The next challenge for cognitive ethologists is to investigate for particular animals the content of their awareness and what life is actually like, for them.

Animal Communication↗

PubMed2003

Changes in MRI signal intensity during hypercapnic challenge under conscious and anesthetized conditions.

Most functional magnetic resonance imaging (fMRI) studies in animals are conducted under anesthesia to minimize motion artifacts. However, methods and techniques have been developed recently for imaging fully conscious rats. Functional MRI studies on conscious animals report enhanced BOLD signal changes as compared to the anesthetized condition. In this study, rats were exposed to different concentrations of carbon dioxide (CO(2)) while conscious and anesthetized to test whether cerebrovascular reactivity may be contributing to these enhanced BOLD signal changes. Hypercapnia produced significantly greater increases in MRI signal intensity in fully conscious animals (6.7-13.3% changes) as when anesthetized with 1% isoflurane (3.2-4.9% changes). In addition, the response to hypercapnia was more immediate in the conscious condition (< 30s) with signal risetimes twice as fast as in the anesthetized state (60s). Both cortical and subcortical brain regions showed a robust, dose- dependent increase in MRI signal intensity with hypercapnic challenge while the animals were conscious but little or no change when anesthetized. Baseline variations in MRI signal were higher while animals were conscious but this was off set by greater signal intensity changes leading to a greater contrast-to-noise ratio, 13.1 in conscious animals, as compared to 8.0 in the anesthetized condition. In summary, cerebral vasculature appears to be more sensitive to hypercapnic challenge in the conscious condition resulting in enhanced T2* MRI signal intensity and the potential for better BOLD signal changes during functional imaging.

Anesthesia↗

PubMed1998

Investigating the biology of consciousness.

The fact that consciousness is a private, first-person phenomenon makes it more difficult to study than other cognitive phenomena that, although being equally private, also have characteristic behavioural signatures. Nonetheless, by combining cognitive and neurobiological methods, it is possible to approach consciousness, to describe its cognitive nature, its behavioural correlates, its possible evolutionary origin and functional role; last but not least, it is possible to investigate its neuroanatomical and neurophysiological underpinnings. In this brief essay I distinguish between two kinds of consciousness: core consciousness and extended consciousness. Core consciousness corresponds to the transient process that is incessantly generated relative to any object with which an organism interacts, and during which a transient core self and transient sense of knowing are automatically generated. Core consciousness requires neither language nor working memory, and needs only a brief short-term memory. Extended consciousness is a more complex process. It depends on the gradual build-up of an autobiographical self, a set of conceptual memories pertaining to both past and anticipated experiences of an individual, and it requires conventional memory. Extended consciousness is enhanced by language.

Biological Evolution↗

PubMed1983

The effects of apomorphine upon local cerebral glucose utilization in conscious rats and in rats anesthetized with chloral hydrate.

The effects of the dopaminergic agonist apomorphine (1 mg . kg-1 i.v.) upon local cerebral glucose utilization in 43 anatomically discrete regions of the CNS were examined in conscious, lightly restrained rats and in rats anesthetized with chloral hydrate by means of the quantitative autoradiographic [14C]2-deoxyglucose technique. In animals anesthetized with chloral hydrate, glucose utilization was reduced throughout all regions of the CNS from the levels observed in conscious animals, although the magnitude of the reductions in glucose use displayed considerable regional heterogeneity. With chloral hydrate anesthesia, the proportionately most marked reductions in glucose use (by 40-60% from conscious levels) were noted in primary auditory nuclei, thalmaic relay nuclei, and neocortex, and the least pronounced reductions in glucose use (by 15-25% from conscious levels) were observed in limbic areas, some motor relay nuclei, and white matter. In conscious, lightly restrained rats, the administration of apomorphine (1 mg . kg-1) effected significant increased in glucose utilization in 15 regions of the CNS (e.g., subthalamic nucleus, ventral thalamic nucleus, rostral neocortex, substantia nigra, pars reticulata), and significant reductions in glucose utilization in two regions of the CNS (lateral habenular nucleus and anterior cingulate cortex). In rats anesthetized with chloral hydrate, the effects of apomorphine upon local glucose utilization were less widespread and less marked than in conscious animals. In only two of the regions (the globus pallidus and septal nucleus), which displayed increased glucose use following apomorphine in conscious rats, were significant increases in local glucose utilization observed with this agent in chloral hydrate-anesthetized rats. In the pars compacta of the substantia nigra, in which apomorphine increased glucose utilization in conscious animals, significant reductions in glucose utilization were observed following apomorphine in rats anesthetized with chloral hydrate. The profound effects of chloral hydrate anesthesia upon local cerebral glucose use, and the modification by this anesthetic regime of the local metabolic responses to apomorphine, emphasize the difficulties which exists in the extrapolation of data from anesthetized animals to the conditions which prevail in the conscious animal.

Animals↗

PubMed2003

Making sense of self-conscious emotion: linking theory of mind and emotion in children with autism.

Self-conscious emotions such as embarrassment and shame are associated with 2 aspects of theory of mind (ToM): (a) the ability to understand that behavior has social consequences in the eyes of others and (b) an understanding of social norms violations. The present study aimed to link ToM with the recognition of self-conscious emotion. Children with and without autism identified facial expressions conscious of self-conscious and non-self-conscious emotions from photographs. ToM was also measured. Children with autism performed more poorly than comparison children at identifying self-conscious emotions, though they did not differ in the recognition of non-self-conscious emotions. When ToM ability was statistically controlled, group differences in the recognition of self-conscious emotion disappeared. Discussion focused on the links between ToM and self-conscious emotion.

Adolescent↗

PubMed1998

Blindsight and shape perception: deficit of visual consciousness or of visual function?

Two people with homonymous right hemianopias were tested on a number of measures of non-conscious and conscious perception of shape in the blind field. Experiment 1 examined preparatory manual adjustments in grasping objects. Both subjects performed well above chance not only in three-dimensional location but also in preforming the hand to the shape, size and orientation of objects. In Experiment 2 single upper-case letters were briefly exposed in the blind field, and subjects made forced choices among 6 alternatives in the sighted field. Performance improved over blocks of trials and was above chance, but not dramatically. In Experiment 3 single upper-case words were briefly presented in the blind field, and subjects chose which of two words exposed after in the intact field was semantically closer. In Experiment 4 subjects had to give the meaning of single ambiguous words (e.g. BANK) presented both visually in the intact field and auditorily. Each ambiguous word was preceded by a single upper-case word briefly presented in the blind field, biasing each meaning on different blocks of trials (e.g. MONEY and RIVER). In Experiment 3, although results were in the appropriate direction, they were not consistently well above chance. By contrast, in Experiment 4 both subjects were consistently semantically biased to a high degree by words in the blind field. Experiments 2, 3 and 4 taken together suggest that indirect techniques (priming) are more sensitive to showing effects of non-conscious perception than direct ones (forced-choice). More importantly the experiments indicate that not only orientation but curvature, structural descriptions of component strokes and spatial ordering of letters are registered non-consciously in the blind field. Experiment 5 examined after-images in the blind and sighted fields, showing veridical conscious perception of shape in the blind field provided it was accompanied by a shape in the sighted field which together formed a good Gestalt. Experiment 6 showed conscious perception of illusory contours spanning the hemifields induced by Kanizsa figures. The experiments suggest that aspects of shape are much better perceived in blindsight than previously thought, that this is independent of their use in motor control, that the main deficit in blindsight is one of consciousness, and that the loss of conscious vision in the blind field is far from total. The effects and their relationship to those in other neuropsychological deficits suggest an intimate link between perceptual consciousness, attention and object perception.

Afterimage↗

PubMed1999

Ketamine preserves and propofol potentiates hypoxic pulmonary vasoconstriction compared with the conscious state in chronically instrumented dogs.

BACKGROUND: The authors tested the hypothesis that ketamine and propofol anesthesia would alter the magnitude of hypoxic pulmonary vasoconstriction compared with the conscious state. In addition, they assessed the extent to which cyclooxygenase pathway inhibition and adenosine triphosphate-sensitive potassium channel inhibition modulate hypoxic pulmonary vasoconstriction in the conscious state, and whether these pathways are altered during propofol anesthesia. METHODS: Twenty conditioned, male mongrel dogs were chronically instrumented to measure the left pulmonary vascular pressure-flow relationship. Pressure-flow plots were measured during normoxia and hypoxia (systemic arterial PO2 reduced to about 60 and about 50 mm Hg) on separate days in the conscious state, during ketamine anesthesia, and during propofol anesthesia. The effects of indomethacin and glibenclamide on the magnitude of hypoxic pulmonary vasoconstriction were also assessed in the conscious and propofol-anesthetized states. RESULTS: Neither ketamine nor propofol had an effect on the baseline pressure-flow relationship during normoxia compared with the conscious state. Hypoxia resulted in stimulus-dependent pulmonary vasoconstriction (P<0.01) in the conscious state. Compared with the conscious state, the magnitude of hypoxic pulmonary vasoconstriction was preserved during ketamine but was potentiated (P<0.01) during propofol anesthesia. Indomethacin enhanced (P<0.01) hypoxic pulmonary vasoconstriction in both the conscious and propofol-anesthetized states. In contrast, glibenclamide only enhanced (P<0.01) hypoxic pulmonary vasoconstriction in the conscious state and had no effect during propofol anesthesia. CONCLUSION: Hypoxic pulmonary vasoconstriction is preserved during ketamine anesthesia but is potentiated during propofol anesthesia. The potentiated response during propofol anesthesia appears to be caused by inhibition of adenosine triphosphate-sensitive potassium channel-mediated pulmonary vasodilation.

Anesthetics, Dissociative↗

PubMed1999

Optimization of conscious sedation in plastic surgery.

The administration of conscious sedation by the plastic surgeon must be safe, efficient, and consistent. In the proper setting, with trained staff and appropriate backup, conscious sedation can allow optimal patient satisfaction with expedient recovery in addition to cost containment. The highly effective local anesthesia afforded by dilute, high-volume ("tumescent") infiltration extends the use of conscious sedation to cases previously performed under general anesthesia or deep sedation. The purpose of this analysis was to identify variables in conscious sedation that affect traditional outcome parameters in ambulatory surgery, particularly the duration of recovery and adverse events such as nausea and emesis. All perioperative and operative records of 300 consecutive patients having plastic surgical procedures under conscious sedation were carefully reviewed. Patients were ASA class I or II by requisite. Conscious sedation followed a standardized administration protocol, using incremental doses of two agents: midazolam (0.25 to 1 mg) and fentanyl (12.5 to 50 mcg). A subset of patients received preoperative oral sedation. Multivariate statistical analysis was conducted using SPSS 8.0 for Windows (SPSS Inc., Chicago, Ill.). Of the 300 patients, same-day discharge was intended for 281. Eight procedure categories were defined. No anesthetic complications occurred. As expected, recovery time was significantly correlated with the duration and type of procedure (p < 0.001) and the total dosage of both intraoperative sedative agents (p < 0.001). Interestingly, a negative correlation with advancing age existed (p < 0.001), likely reflecting the significantly higher intraoperative sedative dosing in younger patients (p < 0.001). When controlled for the effects of procedure duration and intraoperative sedative dosing, two other variables-use of preoperative oral sedation and postoperative nausea/emesis-significantly lengthened recovery time (p = 0.0001 for each). Fifteen unintended admissions occurred secondary to nausea, prolonged drowsiness, or pain control needs. Conscious sedation is an effective anesthetic choice for routine plastic surgical procedures, many of which would commonly be performed under general anesthesia. In our experience with a carefully structured and controlled conscious sedation protocol, the technique has proven to be safe and effective. This analysis of outcome parameters identified two important and potentially avoidable causes of recovery delay following conscious sedation-oral premedication and nausea/emesis. Nausea and emesis were particularly problematic in that they were responsible for 11 of 15 (73 percent) unintended admissions. Preoperative sedation is valuable in certain circumstances, and its use is not discouraged; however, its benefits must be weighed against its unwanted effects, which can include a prolongation of recovery.

Adolescent↗

PubMed2006

Auditory recognition memory, conscious recollection, and executive function in patients with schizophrenia.

BACKGROUND: Dual-process models propose that recognition memory (RM) involves two processes: conscious recollection and familiarity-aware memory. Studies investigating RM in schizophrenia report a selective deficit in conscious recollection and intact levels of familiarity-driven RM for stimuli presented in the visual and olfactory domains. It has been suggested that abnormalities in conscious recollection result from a breakdown in frontal strategic memory processes involved in encoding and retrieval and executive functions linked to reality monitoring and decision making. We investigated three predictions arising from these proposals. Firstly, if conscious recollection abnormalities arise from a central impairment, then these abnormalities should not be domain specific. Secondly, if the deficits in conscious recollection arise from a breakdown in executive processes, deficiencies should be correlated with executive dysfunction. Finally, the conscious recollection deficiencies are likely to be more severe in schizophrenia, a condition associated with marked executive dysfunction relative to Major Depressive Disorder, Recurrent (MDDR), in which executive dysfunction is less marked. METHODS: The remember/know paradigm was used to investigate RM for voices in three groups: patients with schizophrenia (n = 14), patients with MDDR (n = 16), and normal controls (n = 16). Executive function was assessed using the Wisconsin Card Sorting Task. RESULTS: Patients with schizophrenia made significantly fewer remember responses than normal controls (p < 0.01), despite normal levels of discrimination and familiarity-driven auditory RM. Patients with MDDR did not differ significantly from either normal controls or patients with schizophrenia. Executive dysfunction was limited to the schizophrenia group and was not correlated with conscious recollection deficiencies. CONCLUSIONS: Patients with schizophrenia exhibit a deficit in conscious recollection for auditory RM of voices. These findings, when considered alongside remember/know data collected from the same set of patients for olfactory and visual RM, support proposals that abnormalities in conscious recollection stem from a breakdown in central rather than domain-specific processes.

Auditory Perception↗

PubMed2003

Why do seizures cause loss of consciousness?

Model systems are needed for the scientific investigation of consciousness. A good model system should include variable states of consciousness, allowing the relationship between brain activity and consciousness to be investigated. Examples include sleep, anesthesia, focal brain lesions, development, evolution, and epilepsy. One advantage of epilepsy is that changes are dynamic and rapidly reversible. The authors review previous investigations of impaired consciousness in epilepsy and describe new findings that may shed light on both normal and abnormal mechanisms of consciousness. Abnormal increased activity in fronto-parietal association cortex and related subcortical structures is associated with loss of consciousness in generalized seizures. Abnormal decreased activity in these same networks may cause loss of consciousness in complex partial seizures. Thus, abnormally increased or decreased activity in the same networks can cause loss of consciousness. Information flow during normal conscious processing may require a dynamic balance between these two extremes of excitation and inhibition.

Animals↗

PubMed1986

Effects of nimodipine on cerebral blood flow in conscious rat.

The purpose of this study was to determine the effects of the calcium channel blocker nimodipine (NM) on cerebral blood flow in the rat under conscious and anesthesized conditions and to compare these to effects of the drug in other circulations. Regional blood flows were measured using the radioactive microsphere technique. Hemodynamic parameters were assessed at the time of blood flow determinations in conscious rats and in pentobarbital-anesthetized rats. NM was administered i.v. using a cumulative dosing regimen in conscious (6, 24 and 60 micrograms/kg) and anesthetized (6 and 60 micrograms/kg) rats. In conscious rats, NM dose-dependently increased coronary blood flow whereas significantly lowering pressure-rate product and slightly but significantly reduced mean arterial pressure and systemic vascular resistance. In conscious rats, NM had no significant effect on cerebral blood flow or cerebral vascular resistance. In anesthetized rats, cerebral and systemic vascular resistances were higher compared to conscious animals. In anesthetized animals, NM reduced mean arterial pressure and systemic resistance to a greater extent than in conscious rats and significantly increased cerebral blood flow. Base-line coronary resistance was similar in conscious and anesthetized rats and the coronary dilator effects of NM were also similar under the two conditions. These findings suggest that NM is not a selective cerebral vasodilator in rats and that the cerebral dilator effects of this drug are not apparent in conscious rats. Only under the high cerebral resistance condition induced by pentobarbital anesthesia was NM found to be a cerebral vasodilator in the rat.

Anesthesia↗

PubMed2004

Early impairment in consciousness predicts mortality after hemispheric ischemic stroke.

OBJECTIVE: Early predictors of poor outcome after acute ischemic stroke may be useful in selecting patients for potentially beneficial but high-risk interventions. DESIGN: Cohort study of patients given placebo in a randomized clinical trial. SETTING: Multicenter trial at 139 U.S. and 14 Canadian hospitals. PATIENTS: A cohort of 564 placebo-treated patients with major anterior circulation ischemic stroke enrolled in the Clomethiazole in Acute Stroke Study-Ischemic Stroke (CLASS-I) trial. Patients did not have significant impairment in consciousness at baseline and were enrolled within 12 hrs of symptom onset. INTERVENTIONS: Prospective data collection of a number of clinical variables including use of a 6-point level of consciousness scale (1 = awake, 6 = no reaction to pain) to measure patients' level of consciousness at enrollment and 12 additional times during the first 24 hrs after enrollment. The ability of level of consciousness score and additional clinical data to predict 30-day mortality was assessed. MEASUREMENTS AND MAIN RESULTS: At 1 month, 114 of 564 patients (20%) had died. In univariate analysis, factors significantly associated with mortality included older age, white race, higher National Institutes of Health Stroke Scale score, higher serum glucose, atrial fibrillation, and any impairment in level of consciousness (p <.05). After controlling for these factors, increasing level of consciousness score at 3 hrs after enrollment and at all but one subsequent time point was significantly associated with increased mortality (odds ratio, 1.8 per point; 95% confidence interval, 1.2-2.6; p =.003 at 3-hr time point). Maximum level of consciousness score during the initial 24 hrs of monitoring also predicted mortality (odds ratio, 1.9 per point; 95% confidence interval, 1.4-2.5; p <.001). CONCLUSION: The development of a decreased level of consciousness within the initial hours after stroke onset, as evaluated by a simple six-point scale, is a powerful independent predictor of mortality after major anterior circulation ischemic stroke.

Age Distribution↗

PubMed2004

[How often does decreased consciousness of hypoglycaemia occur in children and adolescents with diabetes type 1 and what are its consequences?].

UNLABELLED: The inability of the patient to recognize the risk of hypoglycemia is a very frequent phenomenon, but it is also often an underestimated complication in diabetes treated with insulin. The results of DCCT trial revealed that intensification in insulin therapy increases three-fold the risk of severe hypoglycaemia. Feeling the state of hypoglycaemia is the basic defensive mechanism in patients with diabetes type 1, making possible to start the self treatment. The decreased consciousness of hypoglycaemia makes limitations to intensive insulin therapy, which main aim is to stop later complications. THE AIM OF THE STUDY was to answer the questions: 1. How often does lack of consciousness of hypoglycaemia occur in children and adolescents with diabetes type 1. 2. What are the possible factors influencing appearance of hypoglycaemia. 3. Is lack of hypoglycaemia consciousness of a risk factor for severe hypoglycaemia. MATERIAL AND METHODS: The study was carried out on 318 patients aged x=13.6 yrs (4-21), suffering from diabetes, mean 6.6 yrs (2-18). The study was retrospective taking into consideration the period from 1.01.1998 to 31.12.2002. RESULTS: In the analysis of the questionnaire assessing the occurrence of hypoglycaemia it was found that 82 patients (25.8%) have problems with feeling the state of hypoglycaemia. We analyzed the influence of time of lasting diabetes and we found that patients with a longer duration of the disease more frequently have problems with feeling hypoglycaemia, 57% patients with lack of hypoglycaemia consciousness have bad metabolic control of the disease. In the analyzed period, 64 incidences of severe hypoglycaemia in 48 patients (30 boys and 18 girls) were found. In patients with lack of consciousness of feeling hypoglycaemia the incidences of severe hypoglycaemia occurred ten times more frequently compared to patients who feel hypoglycaemia. Sleeping makes it impossible to perceive early symptoms of hypoglycaemia: in our patients 51 severe incidences (79.7%) occurred at 1.00-3.00 a.m., 6 (9.3%) occurred at daybreak and 7 (11%) in the evening. CONCLUSIONS: 1. In patients with diabetes type 1 the lack of hypoglycaemia consciousness occurs in about 25%. 2. The lack of hypoglycaemia consciousness is closely connected with time of diabetes duration and with recurrence of hypoglycaemia incidences. 3. Patients with lack of hypoglycaemia consciousness are at greater risk for severe hypoglycemia.

Adolescent↗