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PubMed2005

Amnesia for loss of consciousness in carotid sinus syndrome: implications for presentation with falls.

OBJECTIVES: The goal of this study was to compare the clinical characteristics of patients with carotid sinus syndrome who presented with falls with those who presented with syncope. BACKGROUND: Carotid sinus syndrome presents with both falls and syncope. The reasons for this differential presentation are unknown, but amnesia for loss of consciousness may be the underlying cause. METHODS: Two groups of 34 consecutive patients with carotid sinus syndrome as the sole cause of falls and syncope were recruited. Cognitive function and clinical characteristics were compared between the two groups. RESULTS: Syncopal subjects with carotid sinus syndrome were more likely to be older males (18 [53%] vs. 7 [21%] years; p = 0.006) with a longer duration of symptoms (27.9 vs. 13.3 months; p = 0.009) and more soft tissue injuries (19 [56%] vs. 9 [26%]; p = 0.03). Duration of asystole during carotid sinus massage was similar in both groups (5.1 vs. 5.4 s; p = 0.42), but witnessed amnesia for loss of consciousness was more frequent in fallers than those with syncope (21 [95%] vs. 4 [12%]; p < 0.001). Clinical characteristics and cognitive function were otherwise similar in both groups. CONCLUSIONS: Patients with carotid sinus syndrome have similar rates of witnessed loss of consciousness during laboratory testing regardless of symptoms. However, those presenting with falls are far less likely to perceive any disturbance of consciousness than those with syncope, showing for the first time the manner in which such patients manifest symptoms. Cognitive impairment does not explain the amnesia for loss of consciousness seen in fallers with carotid sinus syndrome.

Accidental Falls↗
PubMed2004

The neural substrates of conscious color perception demonstrated using fMRI.

It is well established that seeing color activates the ventral occipital cortex, including the fusiform and lingual gyri, but less is known about whether the region directly relates to conscious color perception. We investigated the neural correlates of conscious color perception in the ventral occipital cortex. To vary conscious color perception with the stimuli-remaining constant, we took advantage of the McCollough effect, an illusory color effect that is contingent on the orientation of grating stimuli. Subjects were exposed to a specific combination of chromatic grating patterns for 10 min to induce the McCollough effect. We compared brain activities measured while the subjects viewed achromatic grating stimuli before (PRE) and after the induction of the McCollough effect (POST) using functional magnetic resonance imaging (fMRI). There were two groups: one group was informed that they would perceive illusory color during the session (INFORMED group), whereas the other group was not informed (UNINFORMED group). The successful induction of the McCollough effect was confirmed in all subjects after the fMRI experiment; nevertheless, only approximately half of the UNINFORMED subjects had been aware of the color during the POST session, while the other half had not. The left anterior portion of the color-selective area in the ventral occipital cortex, presumably V4alpha, was significantly active in subjects who had consciously perceived the color during MR scan. This study demonstrates the activity in a subregion of the color-selective area in the ventral occipital cortex directly related to conscious color perception.

Adult↗
PubMed1999

Perfectionism and self-consciousness in social phobia and panic disorder with agoraphobia.

Social phobics were compared to patients with panic disorder with agoraphobia and normal controls on perfectionism and self-consciousness. On concern over mistakes and doubts about action, social phobics scored higher than patients with panic disorder. Social phobics also demonstrated a higher level of public self-consciousness than patients with panic disorder and when this difference was controlled for the significant differences on perfectionism disappeared. Within each patient group, however, perfectionism was more robustly related to social anxiety than was public self-consciousness, which replicates the findings of Saboonchi and Lundh [Saboonchi, F. & Lundh, L. G. (1997). Perfectionism, self-consciousness and anxiety. Personality and Individual Differences, 22, 921-928.] from a non-clinical sample. The results are discussed in terms of public self-consciousness being a differentiating characteristic of the more severe kind of social anxiety which is typical of social phobia.

Adult↗
PubMed1998

Conscious sedation for in vitro fertilization.

OBJECTIVE: To review the principles and practice of the use of conscious sedation for IVF. DESIGN: The pertinent literature was reviewed and recommendations are provided. RESULT(S): Conscious sedation appears to be the most commonly used method of pain relief for transvaginal retrieval of oocytes. Conscious sedation does not require the presence of an anesthesiologist and can be done in freestanding clinics. Agents commonly used include opioids in combination with benzodiazepines. This combination minimizes pain, decreases anxiety, and provides sedation and some amnesia. Adjuvants such as promethazine and hydroxyzine can also be used but often are not needed. Conscious sedation is well tolerated by patients and does not require highly specialized equipment. However, there are specific safeguards that should be followed. Only a few toxicity studies have been performed, but they are reassuring because they have not found significant effects on fertilization or cleavage. CONCLUSION(S): Conscious sedation appears to be a safe and cost-effective method of providing analgesia and anesthesia for transvaginal retrieval of oocytes.

Benzodiazepines↗
PubMed2000

Object memory effects on figure assignment: conscious object recognition is not necessary or sufficient.

In three experiments we investigated whether conscious object recognition is necessary or sufficient for effects of object memories on figure assignment. In experiment 1, we examined a brain-damaged participant, AD, whose conscious object recognition is severely impaired. AD's responses about figure assignment do reveal effects from memories of object structure, indicating that conscious object recognition is not necessary for these effects, and identifying the figure-ground test employed here as a new implicit test of access to memories of object structure. In experiments 2 and 3, we tested a second brain-damaged participant, WG, for whom conscious object recognition was relatively spared. Nevertheless, effects from memories of object structure on figure assignment were not evident in WG's responses about figure assignment in experiment 2, indicating that conscious object recognition is not sufficient for effects of object memories on figure assignment. WG's performance sheds light on AD's performance, and has implications for the theoretical understanding of object memory effects on figure assignment.

Aged↗
PubMed1986

Disparity of reperfusion arrhythmias after reversible myocardial ischemia in open chest and conscious dogs.

Myocardial reperfusion after brief, reversible ischemia is frequently associated with malignant arrhythmias in experimental animals. These observations have been extrapolated to humans despite being restricted to anesthetized, open chest preparations. No data are available regarding the incidence of reperfusion arrhythmias after reversible (less than 20 minutes) ischemia in the conscious state. Thus, reperfusion arrhythmias after a 15 minute occlusion of the left anterior descending coronary artery were compared in 24 open chest dogs (17 anesthetized with pentobarbital and 7 with chloralose plus urethane) and 25 conscious, unsedated, trained dogs. The incidence of all rhythm disorders (single premature ventricular complexes, pairs, ventricular tachycardia and fibrillation) was markedly and significantly lower in conscious than in either pentobarbital- or chloralose-anesthetized dogs. The disparity was not accounted for by differences in coronary collateral flow, coronary reactive hyperemia or occluded bed size. The conscious animals, however, exhibited lower heart rates and arterial pressures during reperfusion than did the open chest dogs, suggesting a lower level of adrenergic stimulation, which might have contributed to the reduced incidence of reperfusion arrhythmias. Coronary reperfusion after 15 minutes of occlusion is unlikely to precipitate ventricular tachyarrhythmias in the conscious, trained dog, even after severe ischemia. The occurrence of these rhythm disorders in anesthetized models may reflect the influence of surgical trauma or excessive adrenergic activity, or both. Reperfusion arrhythmias after reversible ischemia may be considerably less common in the clinical setting than previously postulated on the basis of open chest animal experiments.

Anesthesia↗
PubMed1997

Consciousness in Neural Networks?

A combined neurophysiological and computational approach is reviewed that leads to a proposal for how neural networks in the temporal cortical visual areas of primates could function to produce invariant object representation and identification. A similar approach is then reviewed which leads to a theory of how the hippocampus could rapidly store memories, especially episodic memories including spatial context, and how later recall of the information to the neocortex could occur. Third, it is argued that the visual and memory mechanisms described could operate without consciousness, and that a different type of processing is related to consciousness. It is suggested that the type of processing related to consciousness involves higher-order thoughts ("thoughts about thoughts"), and evolved to allow plans, formulated in a language, with many steps, to be corrected. It is suggested that it would feel like something to be a system that can think linguistically (using syntax) about its own thoughts, and that the subjective or phenomenal aspects of consciousness arise in this way. It is further suggested that "raw sensory feels" arise in evolution because once some types of processing feel like something by virtue of a system capable of higher-order thoughts, it is then parsimonious to postulate that sensory and related processing, which has to be taken into account in that processing system, should feel like something. It is suggested that it is this type of processing, which must be implemented in neural networks, which is related to consciousness.

Journal Article↗
PubMed1996

Needle Laparoscopy Under Conscious Sedation

Twenty-two patients underwent needle laparoscopy between July 5, 1995, and February 13, 1996, for diagnostic and operative laparoscopy. They were given the choice of local versus general anesthesia for the procedure. Eight women chose conscious sedation and 10 requested general anesthesia. The various combinations of conscious sedation were midazolam, fentanyl, intravenous ketorolac, and field block with 1% lidocaine infraumbilically and in the midsuprabubic region. A 2-mm needle laparoscope was inserted intraabdominally. Pressure was maintained at 12 mm Hg, and volume of gas at 3 L. Operative laparoscopic procedures included drainage of ovarian cysts and lysis of adhesions with 2-mm microinstruments. In two women the procedure was converted to conventional laparoscopy for lysis of extensive pelvic adhesions and salpingectomy. One large bowel perforation which occurred during needle laparoscopy was repaired by minilaparotomy with no consequences. All patients who requested conscious sedation tolerated the procedure well, including one who underwent lysis of adhesions. No complications resulted from conscious sedation. Needle laparoscopy can be performed effectively under conscious sedation in properly selected patients, but not all women are candidates for the procedure. Proper patient selection and counseling are important.

Journal Article↗
PubMed2003

The disunity of consciousness.

Attempts to decode what has become known as the (singular) neural correlate of consciousness (NCC) suppose that consciousness is a single unified entity, a belief that finds expression in the term 'unity of consciousness'. Here, I propose that the quest for the NCC will remain elusive until we acknowledge that consciousness is not a unity, and that there are instead many consciousnesses that are distributed in time and space.

Journal Article↗
PubMed1999

The neural correlates of conscious experience: an experimental framework.

Demonstrating that neural activity 'represents' physical properties of the world such as the orientation of a line in the receptive field of a nerve cell is a standard procedure in neuroscience. However, not all such neural activity will be associated with the mental representations that form the contents of consciousness. In some cases, such as when patients with blindsight correctly 'guess' the location of a stimulus, neural activity is associated with physical stimulation and with appropriate behaviour, but not with awareness. To identify the neural correlates of conscious experience we need to identify patterns of neural activity that are specifically associated with awareness. Experiments aimed at making such identifications require that subjects report some aspect of their conscious experience either verbally or through some pre-arranged non-verbal report while neural activity is measured. If there is some characteristic neural signature of consciousness, then this should be distinguishable from the kinds of neural activity associated with stimulation and/or behaviour in the absence of awareness. It remains to be seen whether the neural signature of consciousness relates to the location of the neural activity, the temporal properties of the neural activity or the form of the interaction between activity in different brain regions.

Journal Article↗
PubMed2006

Balanced conscious sedation with intravenous induction and inhalational maintenance for patients requiring endoscopic and/or surgical procedures.

BACKGROUND AND OBJECTIVE: The use of inhalation sedation with sub-anaesthetic concentrations of sevoflurane and nitrous oxide mixture is expected to reduce amounts of intravenous sedative drugs needed to produce a balanced sedation with the benefits of having reduced side-effects. METHODS: Eighty-two patients requiring endoscopic and/or surgical procedures under conscious sedation and local anaesthesia were recruited for this pilot study. Conscious sedation was induced with a titrated dose of midazolam and propofol given intravenously until the clinical end-point of conscious sedation was achieved. Subsequently, during the procedure, the patient was asked to breathe sevoflurane 0.1-0.3% and a fixed ratio of 40% nitrous oxide in oxygen given through a face mask. RESULTS: In 78 patients (95.1%), the treatment was completed successfully. Patients were discharged back to the wards within 4-16 min (10.1) without significant side-effects. Treatment was satisfactorily accepted by 38 patients (48.7%) and considered excellent by 40 patients (51.3%). CONCLUSIONS: The use of titrated doses of intravenous sedative drugs for induction of conscious sedation followed by the use of low concentrations (0.1-0.3%) of sevoflurane combined with 40% nitrous oxide for maintenance of conscious sedation in patients requiring endoscopic and/or surgical procedures under local anaesthesia, has the potential advantages of reducing amounts of intravenous sedative drugs, less likelihood of problems from drug side-effects and fast recovery and discharge time. Further investigations to establish the technique are currently in progress.

Administration, Inhalation↗
PubMed1990

Differential effects of anesthetic regimens on gentamicin pharmacokinetics in the rat: a comparison with chronically catheterized conscious animals.

The intravenous disposition of gentamicin was compared in the conscious chronically catheterized rat with that in rats anesthetized using five injectable laboratory anesthetics. Gentamicin plasma clearance in the conscious rat was significantly higher than in animals anesthetized with urethane, fentanyl/fluanisone/midazolam, pentobarbitone, or ketamine/midazolam but similar to that in rats anesthetized with alphaxolone/alphadolone. Urethane anaesthesia resulted in a significantly lower gentamicin clearance than in all other groups. Gentamicin clearance in rats anesthetized with alphaxolone/alphadolone was significantly higher than in rats anesthetized with either fentanyl/fluanisone/midazolam or urethane. No significant differences in the volume of distribution of gentamicin were observed between any of the groups studied, either anesthetized or conscious. Carboxyinulin blood clearance in the conscious group was significantly higher than that with urethane, fentanyl/fluanisone/midazolam, pentobarbitone, or ketamine/midazolam but not significantly different from alphaxolone/alphadolone-anesthetized animals. The differences in carboxyinulin clearance were noted to be proportional to the differences in gentamicin clearance (r2 = 0.98). These results demonstrate that the choice of anesthetic used in laboratory pharmacokinetic studies is important. Gentamicin clearance was higher in conscious than anesthetized rats, and it may be prudent to use chronically catheterized animals in pharmacokinetic studies.

Anesthetics↗
PubMed2002

Process-dissociation procedure: a testable model for considering assumptions about the stochastic relation between consciously controlled and automatic processes.

This paper presents an extension of the process-dissociation procedure with wordstem completion, which makes possible the measurement of the stochastic relationship between consciously controlled and automatic processes. By means of an indirect wordstem completion test, the conditional probabilities of conscious remembering with and without automatic processes can be successfully determined. A multinomial model for the evaluation of this extended process-dissociation procedure is presented. This model makes the distinction between voluntary and involuntary conscious memory processes possible and has been applied to two experiments discussed in this paper. The results show that the assumption of stochastic independence is often violated, albeit not as strongly as predicted by the redundancy or exclusivity model variants. Two conscious processes were found, voluntary and involuntary conscious memory processes, each with a different probability of occurrence.

Attention↗
PubMed1983

Self-consciousness, self-esteem, and success-failure as determinants of alcohol consumption in male social drinkers.

An experiment was conducted to test the proposition that alcohol is consumed as a function of the quality of past performances and the individual's level of private self-consciousness. One hundred and twenty male subjects were randomly given success or failure feedback on an intellectual task. They then participated in a separate "wine-tasting" experiment in which they were allowed to regulate alcohol consumption. As predicted, high self-conscious subjects who had received failure feedback drank significantly more wine than did high self-conscious subjects who received success feedback. Consumption by low self-conscious subjects fell between these extremes and did not vary as a function of success and failure. Additional data indicated that these results were mediated by differential sensitivity to the positive or negative implications of success/failure by high and low self-conscious subjects. The results are discussed in terms of their implications for theoretical accounts of the psychological antecedents of alcohol consumption.

Achievement↗
PubMed2002

The nonconsciousness of self-consciousness.

Five studies demonstrated that private self-consciousness is associated with nonconscious, automatic behaviors. In 2 studies, high but not low self-conscious individuals walked more slowly following exposure to an implicit elderly prime. In a 3rd study, high but not low self-conscious individuals showed improved performance following exposure to a subliminal success prime relative to a subliminal failure prime. In a 4th study, subliminal exposure to an angry prime was shown to increase blood pressure relative to a relax prime. In a final study, the latter effect was shown to be true only for high self-conscious individuals and only for subliminal presentations. Results are discussed in terms of their implications for understanding a variety of effects associated with self-consciousness and self-awareness.

Adult↗
PubMed1990

Consciousness of attention and expectancy as reflected in event-related potentials and reaction times.

The effects of conscious expectancies and attention on event-related potentials (ERP) and choice reaction times (RT) and their modulation by stimulus sequence were studied. Subjects retrospectively reported their expectancy of, and attention to, the terminal tones of short series. ERPs and RTs showed the usual sequential effects that were modulated by practice. As ratings were affected by only a few of the stimulus sequence, conscious access to sequence-based expectancy or attention appears to be fragmentary. Increased P300 amplitude with attention indicates conscious access to processing capacity. RTs and P300 latencies suggest stimulus processing time to decrease with sequence-based and consciously accessible expectancy. Differential effects of stimulus sequences and conscious expectancies on P300 amplitude indicate influences of two varieties of expectancy.

Arousal↗
PubMed2006

Challenging racism, sexism, and social injustice: support for urban adolescents' critical consciousness development.

This mixed-model study examined the relationship between urban adolescents' perceived support for challenging racism, sexism, and social injustice from peers, family, and community members and their critical consciousness development. These relationships were examined by relating participants' qualitative perceptions of support for challenging racism, sexism, and social injustice to quantitative data obtained from Likert-type measures of the reflection and action components of critical consciousness. Perceived support for challenging racism, sexism, and social injustice had a significant impact upon the reflection component of critical consciousness; the significance criterion was supported by effect size estimates. Support for challenging racism, sexism, and social injustice was not significantly related to the action component of critical consciousness. Participants perceived the most support for challenging racism, moderate support for challenging social injustice, and the least support for challenging sexism. Additionally, female participants perceived more support for challenging sexism than male participants. These results suggest that the informal interactions of urban adolescents play a role in shaping their critical consciousness, and hold implications for psychosocial interventions and research with marginalized populations.

Adolescent↗
PubMed2006

Conscious sedation training received by specialist registrars in restorative dentistry in the UK: a survey.

OBJECTIVE: To investigate conscious sedation training received by Specialist Registrars in Restorative Dentistry (SpRs) during their training programme. DESIGN: Postal questionnaire survey in the UK. Setting SpRs and recently certificated Consultants in Restorative Dentistry (CRDs). METHOD: A questionnaire was sent to 81 current SpRs in Restorative Dentistry and CRDs who had been awarded a Certificate of Completion of Specialist Training within the previous three years. One follow-up letter was sent to non-responders. RESULTS: The completed questionnaire was returned by 67 (83%) SpRs and CRDs. Analysis revealed that 44 (69%) respondents had received conscious sedation training during their specialist training programme and that 50 (78%) respondents carried out restorative dental treatment under sedation during their programme. Thirteen (20%) respondents had not received conscious sedation training in their programmes but eight (13%) SpRs indicated that sedation training was planned. Training experiences differed throughout the UK: 29 (66%) respondents gained experience in inhalational and single agent intravenous sedation techniques under the supervision of an experienced colleague. Fourteen (32%) respondents who performed sedation had not been on a resuscitation course in the previous year. These included nine (21%) current SpRs. Sixteen (53%) current SpRs intended to offer restorative dental treatment under sedation after specialist training. Fifty-nine (92%) respondents thought that all SpRs in Restorative Dentistry should receive sedation training and 42 (71%) thought that a structured core course would be the most appropriate format. CONCLUSIONS: Although the majority of SpRs and recently certificated CRDs considered that all SpRs should receive training in conscious sedation via a core course during the restorative dentistry training programme, a small number had not received or planned to undertake such training. Conscious sedation training experiences differed throughout the UK and SpRs treated a wide range of deserving patient categories under sedation. It is encouraging that many SpRs hope to continue employing sedation techniques after their restorative dentistry training has finished. The results of this survey should inform all those involved with restorative dentistry training programmes.

Anesthesia, Dental↗