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At least 1,675 records · Page 93Linked to original sources
PubMed2003

Use of deep intravenous sedation with propofol and the laryngeal mask airway during transesophageal echocardiography.

OBJECTIVE: To describe the use of either deep intravenous sedation with propofol or light sedation with midazolam and topical anesthesia during transesophageal echocardiography (TEE) and to report the incidence of respiratory complications and their management. DESIGN: Retrospective study from March 2000 through August 2002. SETTING: Single institution, specialized cancer center. PARTICIPANTS: All patients undergoing TEE examination in the specified time period (n = 42). MAIN RESULTS: Eight patients received light sedation and 34 patients received deep intravenous sedation with propofol. An airway event occurred in one patient in the light sedation group and in six patients in the deep sedation group. The patient in the light sedation group was managed with the use of a face-mask and a manual resuscitation bag. All airway events in the deep sedation group were managed successfully using the laryngeal mask airway (LMA). CONCLUSION: Deep sedation with intravenous propofol can provide both excellent patient comfort and optimal conditions for TEE examination, particularly in patients who may require more lengthy procedures or in whom other techniques have failed. Although the incidence of respiratory depression was higher in patients receiving deep sedation with propofol than in patients who were lightly sedated (17.6% versus 12.5%, respectively), all six patients who had respiratory depression while under deep sedation with propofol were successfully ventilated using the LMA trade mark, without the need to remove the TEE probe and without terminating the examination prematurely. In contrast, in the one patient in the light sedation group who had respiratory depression, the TEE probe had to be removed to ventilate the patient via a face mask, and the procedure was cancelled.

Adult↗
PubMed2002

[Influence of thermoplastic masks on the absorbed skin dose for head and neck tumor radiotherapy].

The influence of thermoplastic masks used in clinical routine for patient immobilization in head and neck radiotherapy treatment on the absorbed skin dose has been investigated at Gustave-Roussy Institute. The measurements were performed in 60Co gamma-rays, 4 and 6MV X-rays and in 8 and 10MeV electron beams. Initially, the measurements were performed with thermoluminescent dosimeters (LiF) and a NACP chamber on a polystyrene phantom in order to study the influence of physical parameters (distance, field size, energy...) on first millimeters depth variation dose. The study was completed with in vivo measurements on 14 patients using various dosimeters (thermoluminescent detectors, diodes) in order to assess the increase of dose on first millimeters depth and to verify the delivered dose during treatment sessions (quality control). In treatment conditions, masks lead to an important increase of dose on the first millimeter in 60Co gamma-rays beams (dose value normalized to maximum of dose increase from 57.1% to 77.7% for 0.5 mm-water depth and from 78.5% to 88% for 1 mm-water depth); its contribution is less important in 4 and 6 MV X-rays beams (dose value normalized to maximum of dose increase from 49.5% to 63.2% for 0.5 mm-water depth and from 59% to 70.1% for 1 mm-water depth). Concerning 8 and 10 MeV electron beams, the normalized dose value increase respectively from 78.4% to 81.7% and from 82.2% to 86.1% for 0.5 mm-water depth. In vivo dosimetry enabled the quality control of delivered dose during treatment. Measured dose is in agreement within +/- 5% with the prescribed dose for 92.3% of cases. In routine, in vivo dosimetry allowed to quantify the increase of skin dose induced by thermoplastic masks for various energies of photon and electron beams as well as quality control.

Head and Neck Neoplasms↗
PubMed1987

The suppression of palatal (or intra-tympanic) myoclonus by tinnitus masking devices. A preliminary report.

Twelve cases of well established palatal myoclonus with objective clicking tinnitus were treated with tinnitus masking techniques. After a few months, three patients became completely symptom free, one for five years now. A further four patients continued to get periods of relief from their clicking sounds with continuous masking, and four patients found the distracting effects of the white noise helped them. The mechanism of palatal myoclonus is discussed with reference to the part played by masking therapy in this condition.

Adolescent↗
PubMed1997

Neonatal and paediatric fibre-optic laryngoscopy and bronchoscopy using the laryngeal mask airway.

Endoscopy of the upper airways in neonates and infants was traditionally been accomplished using rigid laryngoscopes and bronchoscopes. The laryngeal mask may be used both to control the airway for anaesthetic ventilation and to guide a fibre-optic endoscope to the laryngeal inlet and beyond. We report our experience with five neonatal and paediatric cases where fibre-optic laryngoscopy and bronchoscopy were performed through the laryngeal mask airway. All were cases in which standard rigid endoscopy had proved difficult with only a poor and restricted view of the laryngeal inlet being obtained due to the age of the infants, or abnormal anatomy of the upper airways. No problems have been encountered with maintenance of the airway or with endoscopic view obtained. In fact in neonatal patients, this technique has been found to be preferable with regard to safety and ease of use when compared to the ventilating bronchoscope. With the size 1 laryngeal mask airway it is not possible to simultaneously ventilate and endoscope the patient. Cases included, a vascular ring, Goldenhar's syndrome, laryngomalacia, supraglottis and vocal fold paresis. This technique provides a secure method of maintaining anaesthetic ventilation during airway endoscopy, and also a means of easily locating the glottis.

Bronchoscopy↗
PubMed2002

Use of the intubating laryngeal mask airway in a case of ankylosing spondylitis for coronary artery bypass grafting.

The intubating laryngeal mask airway is a modification of the conventional laryngeal mask and is used as a tool for difficult intubation. It can be inserted without placing the head and neck in the Magill position and has been used successfully in cervical spine injuries. Reported is a case of successful insertion of the intubating laryngeal mask and subsequent intubation through it in a patient with ankylosing spondylitis with cervical involvement resulting in a fixed flexion deformity who underwent coronary artery bypass grafting.

Coronary Artery Bypass↗
PubMed2005

Pressure support ventilation with the ProSeal laryngeal mask airway. A comparison of sevoflurane, isoflurane and propofol.

BACKGROUND AND OBJECTIVE: There are no data about the influence of anaesthetics on cardiovascular variables during pressure support ventilation of the lungs through the laryngeal mask airway. We compared propofol, sevoflurane and isoflurane for maintenance of anaesthesia with the ProSeal laryngeal mask airway during pressure support ventilation. METHODS: Sixty healthy adults undergoing peripheral musculo-skeletal surgery were randomized for maintenance with sevoflurane end-tidal 2%, isoflurane end-tidal 1.1% or propofol 6 mg kg(-1) h(-1) in oxygen 33% and air. Pressure support ventilation comprised positive end-expiratory pressure set at 5 cmH2O, and pressure support set 5 cmH2O above positive end-expiratory pressure. Pressure support was initiated when inspiration produced a 2 cmH2O reduction in airway pressure. A blinded observer recorded cardiorespiratory variables (heart rate, mean blood pressure, oxygen saturation, airway occlusion pressure, respiratory rate, expired tidal volume, expired minute volume and end-tidal CO2), adverse events and emergence times. RESULTS: Respiratory rate and minute volume were 10-21% lower, and end-tidal CO2 6-11% higher with the propofol group compared with the sevoflurane or isoflurane groups, but otherwise cardiorespiratory variables were similar among groups. No adverse events occurred in any group. Emergence times were longer with the propofol group compared with the sevoflurane or isoflurane groups (10 vs. 7 vs. 7 min). CONCLUSION: Lung ventilation is less effective and emergence times are longer with propofol than sevoflurane or isoflurane for maintenance of anaesthesia during pressure support ventilation with the ProSeal laryngeal mask airway. However, these differences are small and of doubtful clinical importance.

Adult↗
PubMed1992

Span of apprehension in schizophrenic patients as a function of distractor masking and laterality.

Twenty schizophrenic patients, 10 depressed control patients, and 20 normal control subjects were compared in a forced-choice, target-detection method for assessing the span of apprehension. The detection task required the subject to report which of 2 target letters was presented among 7 other (distractor) letters. Performance accuracy was examined as a function of target location and whether the distractor letters were masked after their presentation. The backward masking of the distractors improved target-detection accuracy of both control groups but reduced accuracy of the schizophrenic group. In addition, schizophrenics performed particularly poorly on targets located in the left half or lower half of the display. These results suggest that response to the masking of distractors may be a new index of attentional shortcoming in schizophrenia. Various theoretical explanations for the target location findings are also discussed.

Adult↗
PubMed1993

On the automatic nature of phobic fear: conditioned electrodermal responses to masked fear-relevant stimuli.

Normal subjects (n = 64) were exposed either to pictures of snakes and spiders or to pictures of flowers and mushrooms in a differential conditioning paradigm in which one of the pictures signaled an electric shock. In a subsequent extinction series, these stimuli were presented backwardly masked by another stimulus for half of the subjects, whereas the other half received non-masked extinction. In support of a hypothesis that suggests that nonconscious information-processing mechanisms are sufficient to activate responses to fear-relevant stimuli, differential skin conductance response to masked conditioning and control stimuli was obvious only for subjects conditioned to fear-relevant stimuli. These results were replicated in a second experiment (n = 32), which also demonstrated that the effect was unaffected by which visual half-field was used for stimulus presentation.

Adult↗
PubMed1993

Backward-masking performance in chronic and nonchronic schizophrenics, affectively disturbed patients, and normal control subjects.

There is ample evidence that schizophrenics exhibit a backward masking deficit. To what extent other psychotic patients are susceptible to visual masking is still an open question. Likewise, differences between subgroups of schizophrenics have to be further explored. In the present study a computerized backward masking task was applied to 30 schizophrenics, 18 affectives and 20 normals. Results confirmed previous findings of a performance deficit in the schizophrenics. However, affectively disturbed patients performed even poorer than the schizophrenics. The most outstanding finding when the group of schizophrenics was split into different subgroups was the significant differences that appeared between chronic and nonchronic patients. The latter group (n = 8) performed as well as the normals, while the chronic schizophrenics (n = 22) showed evidence of a performance deficit comparable to the affectives.

Adult↗
PubMed1998

Are high-schizotypal normal participants distractible or limited in attentional resources? A study of latent inhibition as a function of masking task load and schizotypy level.

Two experiments with normal participants examined the effects of masking and masking task load on latent inhibition (LI, poorer learning for a previously exposed irrelevant stimulus than for a novel stimulus) as a function of level of schizotypality. In Experiment 1, a masking task was needed to produce LI. In Experiment 2, with low load, LI was present in low- but not high-schizotypal participants. In high load, LI was abolished in low-schizotypal participants, but only approached significance in high-schizotypal participants. The data support a distraction- rather than a resource-limitation model of attentional dysfunction in high-schizotypal normal participants. In addition, the data indicate that obtaining LI requires that some attention be initially allocated to the preexposed stimulus and then reduced. Implications of the model for understanding attentional dysfunction in schizophrenia are discussed.

Adult↗
PubMed1996

Attentional capture by abrupt onsets: new perceptual objects or visual masking?

The authors have shown that an object appearing abruptly in a previously blank location is efficiently detected in visual search when it is embedded in an array of objects without abrupt onset (term no-onset stimuli). In these experiments, no-onset stimuli appeared well before the onset stimulus but were camouflaged by additional line segments rendering the stimuli unidentifiable. B. S. Gibson (1996) claims that the availability of the no-onset stimuli was delayed relative to that of the abrupt onset stimulus because of forward masking. The authors show that forward masking is unlikely to be a significant factor in their experiments, and 3 new experiments are reported that undermine Gibson's masking account. Observed differences in the efficiency with which onset and no-onset stimuli are processed in visual search are due to attentional capture by new perceptual objects and to a relatively sluggish process of updating existing object representations.

Attention↗
PubMed1978

Geometric and semantic similarity in visual masking.

Semantic and geometric or physical similarity were manipulated separately in a backward-masking situation. When the target was a word to be read aloud, formal similarity between the letters of target and mask facilitated target recognition, as did associative similarity. Masking a target word by its own anagram also facilitated whole word report. In contrast, formal similarity was inhibitory rather than facilitatory of report when the target was spelled letter-by-letter, rather than read whole. This was true even for the same target words whose whole report was facilitated by formal similarity. A model to account for this reversal in the broader context of the neural substrate of reading is advanced. It is proposed that letter and word processing are fundamentally different in that letters are recognized by hierarchical feature analysis while words are stored and recognized wholistically by diffuse and redundant networks. Implications of the results for the study of reading are discussed.

Female↗
PubMed1990

Mechanism of age-related differences in frequency discrimination with backward masking: speed of processing or stimulus persistence?

In Experiment 1, frequency-discrimination thresholds were estimated in a 2-interval, forced-choice, backward masking procedure with a masker acoustically dissimilar to the targets. Young subjects were more efficient in escaping the effects of masking than were their elderly counterparts. In Experiment 2, young and elderly subjects performed the same task, with a masker acoustically similar to the targets and with a target-dissimilar masker. Under target-similar masking and at short target-masker intervals, the elderly demonstrated significant improvement, reaching the level of performance of the young, whereas under the target-dissimilar masker, the age-related differences were restored. Both age-related slowing of information processing and increase in stimulus persistence can account for the results of Experiment 1, but only increased stimulus persistence explains the results of Experiment 2.

Adolescent↗
PubMed2002

Dissociation of sensitivity and response bias in children with attention deficit/hyperactivity disorder during central auditory masking.

Forty-three children (ages 7.0-14.5 years old) with and without attention deficit/hyperactivity disorder (ADHD), combined type had thresholds for detection of a 500-Hz pure tone estimated with and without a noise masker in the contralateral ear. The ear receiving the signal in the masked condition was varied randomly. A single-interval maximum-likelihood method estimated thresholds and false-alarm rate. Whereas the increase in threshold in children with ADHD in the presence of contralateral masking was comparable with controls, the increase in false-alarm rate was significantly greater. This dissociation between changes in sensitivity and response bias in the presence of masking noise supports suggestions that children with ADHD have difficulty inhibiting maladaptive responses and indicates that this deficit is quantifiable using psychoacoustic methods.

Adolescent↗
PubMed2004

Qualitative differences between conscious and nonconscious processing? On inverse priming induced by masked arrows.

In general, both consciously and unconsciously perceived stimuli facilitate responses to following similar stimuli. However, masked arrows delay responses to following arrows. This inverse priming has been ascribed to inhibition of premature motor activation, more recently even to special processing of nonconsciously perceived material. Here, inverse priming depended on particular masks, was insensitive to contextual requirements for increased inhibition, and was constant across response speeds. Putative signs of motor inhibition in the electroencephalogram may as well reflect activation of the opposite response. Consequently, rather than profiting from inhibition of primed responses, the alternative response is directly primed by perceptual interactions of primes and masks. Thus there is no need to assume separate pathways for nonconscious and conscious processing.

Adult↗
PubMed2005

Repeated masked category primes interfere with related exemplars: new evidence for negative semantic priming.

In 4 experiments, the authors found evidence for negatively signed masked semantic priming effects (with category names as primes and exemplars as targets) using a new technique of presenting the masked primes. By rapidly interchanging prime and mask during the stimulus onset asynchrony, they increased the total prime exposure to a level comparable with that of a typical visible prime condition without increasing the number of participants having an awareness of the prime. The negative effect was observed for only low-dominance exemplars and not for high-dominance exemplars. The authors found it using lexical decision (Experiments 1 and 2), lexical decision with a response-window procedure (Experiment 3), and the pronunciation task (Experiment 4). The results are discussed with regard to different theories on semantic priming.

Adult↗
PubMed2005

Emotional conditioning to masked stimuli and modulation of visuospatial attention.

Two studies investigated the effects of conditioning to masked stimuli on visuospatial attention. During the conditioning phase, masked snakes and spiders were paired with a burst of white noise, or paired with an innocuous tone, in the conditioned stimulus (CS)+ and CS- conditions, respectively. Attentional allocation to the CSs was then assessed with a visual probe task, in which the CSs were presented unmasked (Experiment 1) or both unmasked and masked (Experiment 2), together with fear-irrelevant control stimuli (flowers and mushrooms). In Experiment 1, participants preferentially allocated attention to CS+ relative to control stimuli. Experiment 2 suggested that this attentional bias depended on the perceived aversiveness of the unconditioned stimulus and did not require conscious recognition of the CSs during both acquisition and expression.

Acoustic Stimulation↗
PubMed2006

Current concerns in visual masking.

Theories of emotion postulate that emotional input is processed independently from perceptual awareness. Although visual masking has a long tradition in studying whether emotional pictures are processed below a supposed threshold of perceptual awareness (subliminal perception), a consensus has yet to be reached. This article reviews current concerns in the use of visual masking. These include a reliable presentation method, the role of masking pictures, common definitions of awareness and their problems, current models of awareness, and neural mechanisms. A useful strategy may be the study of dose-response relationships between awareness and emotion processing that avoids a dichotomous view of awareness and allows conclusions about the relative independence of emotional processing from awareness.

Affect↗