Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “MASKS”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,171 records · Page 65Linked to original sources
PubMed1962

Method for evaluating effectiveness of surgical masks.

Greene, V. W. (University of Minnesota, Minneapolis) and D. Vesley. Method for evaluating effectiveness of surgical masks. J. Bacteriol. 83:663-667. 1962.-A portable isolation box, provided with a filtered air supply and a means of access for a test subject's head, was attached to an Andersen Sampler and used to measure orally expelled bacterial contaminants before and after masking. This technique yielded more detailed quantitative information than was obtained by either sedimentation plates or Andersen sampling in an unconfined space. During talking, unmasked subjects expelled more than 5,000 bacterial contaminants per 5 ft(3); 7.2% of the contaminants were associated with particles less than 4 mu in diameter. Masked subjects expelled an average of 19 contaminants/5 ft(3); 63% were less than 4 mu in diameter. Mask efficiencies varied according to particle size of the contaminants. This technique is adaptable for routine evaluation of an individual's contribution to environmental contamination.

Humans↗
PubMedDate not supplied

[Utilization of laryngeal masks. Preliminary study. 21 cases. Department of Anesthesia-Resuscitation, Yaounde, Cameroon].

The authors present a preliminary and retrospective study about the utilization of laryngeal mask. 21 patients underwent surgery concerning short or mid term intervention. A positioning of a laryngeal mask was easy with 83 p.c. of success. Although no shortcomings appeared in this series, one must know such a possibility and must take it into considerations. Not at all replacing endotracheal intubation, the laryngeal mask is in peculiar situations an other possibility of protection of respiratory tract, and of ventilation be spontaneous manual or mechanical. The advantages of laryngeal mask versus facial one are obvious.

Adult↗
PubMed1995

Laryngeal mask airway in paediatric otolaryngologic surgery.

The laryngeal mask airway (LMA) is a relatively recent development that fills the gap in airway management between endotracheal intubation and the use of a face mask. The device is inserted blindly into the pharynx, forming a low-pressure seal around the laryngeal inlet permitting gentle positive-pressure ventilation. It allows the administration of inhaled anaesthetic agents through a minimally stimulating airway. This factor, combined with its ease of insertion, suggested that the laryngeal mask airway might offer some distinct advantages in otolaryngologic paediatric surgery. Our experience in utilizing the laryngeal mask in tonsillectomy and adenoidectomy, and in myringotomies with insertion of ventilating tubes is described, and its advantages and disadvantages are discussed.

Adenoidectomy↗
PubMed2004

Comparison of spinal vs general anesthesia via laryngeal mask airway in inguinal hernia repair.

HYPOTHESIS: The use of laryngeal mask airway and propofol in inguinal hernia repair results in shorter operative and recovery room times. DESIGN: Randomized control trial. SETTING: University hospital. PATIENTS: From May 2000 to March 2002, a convenience sample of 79 patients was invited to participate; 34 entered the study. Fifteen patients were randomized to subarachnoid block, and 18 patients were randomized to laryngeal mask airway. No patients withdrew from the study because of adverse effects. All study subjects were followed up for 6 months. INTERVENTION: General anesthesia via laryngeal mask airway or lidocaine subarachnoid block anesthesia for inguinal hernia repair. MAIN OUTCOME MEASURES: Operative and recovery room times; surgeon evaluation of the adequacy of the anesthetic technique; 36-Item Short-Form Health Survey scores before and after operation. RESULTS: Total time from entry into the operating room to discharge home was slightly longer in the subarachnoid block group (285 vs 262 minutes; 95% confidence interval, 251-317 minutes) but this difference was not statistically or clinically significant. Patient satisfaction was high with both techniques; patient-reported outcomes were the same. Surgeons rated muscle relaxation and exposure better with the subarachnoid block. CONCLUSIONS: We found no differences between short-acting spinal anesthesia and general anesthesia via laryngeal mask airway with intravenous propofol in efficiency or in early or late outcomes after elective inguinal hernia repair. Surgeon and patient preferences appear to be the most important reasons for selecting an anesthetic technique for individual patients undergoing inguinal hernia repair.

Adult↗
PubMed2003

Use of a larynyngeal mask airway during aortic valve replacement.

We report the elective use of a laryngeal mask airway during cardiac surgery for congenital tracheal stenosis. A 53-year-old woman with severe aortic valve stenosis was scheduled for aortic valve replacement. During anesthesia induction, the anesthesiologists attempted conventional intubation but failed. Fiberoptic tracheal examination and computed tomography showed a tracheal stenosis with 5 mm minimal diameter. A laryngeal mask airway was used at the patient's rescheduled surgery. The laryngeal mask airway use did not lead any surgical complication. We concluded that the laryngeal mask airway may be considered as an alternative to conventional intubation in patients with tracheal stenosis.

Aortic Valve↗
PubMed1995

Laryngeal mask airway with mouth opening less than 20 mm.

We describe the use of a laryngeal mask airway in three adult patients whose mouth opening varied from 12 mm to 18 mm. The first patient's incisal opening was 12 mm. His airway was otherwise normal and the standard laryngeal mask was used as the definitive airway for the 90 min revision of facial scars and bone graft to mandible. The second patient, who had an incisal opening of 18 mm, was scheduled for posterior fossa craniotomy. She adamantly refused awake fibreoptic tracheal intubation. Following induction of general anaesthesia, a standard laryngeal mask was inserted and, through this, fibreoptic intubation was performed. The third patient, in addition to a mouth opening of only 18 mm, had limited neck movement from previous flap reconstruction following mandibulectomy, hemiglossectomy and radical neck dissection. For three more reconstructive head and neck procedures that ranged from 90 min to nine hours, the flexible reinforced laryngeal mask was inserted under topical anaesthesia and its correct position confirmed by fibreoptic laryngoscopy before induction of general anaesthesia. Maintenance of anaesthesia in all cases was uneventful and there were no postoperative complications.

Adult↗
PubMed2002

Laryngeal mask cuff inflation at removal does not affect early postoperative laryngopharyngeal morbidity.

PURPOSE: We assessed the effect of cuff inflation of the laryngeal mask airway at removal on sore throat, pharyngeal morbidity and airway complications. METHODS: In a prospective randomized trial, we used a standardized technique of anesthesia and of laryngeal mask insertion in 126 consecutive day-case patients. Postoperatively, on eye opening, the masks were removed either inflated (Group A) or deflated (Group B) and examined for blood by a blinded observer. Episodes of coughing, gagging, laryngospasm, hiccups and retching, and symptoms of sore throat and hoarseness were recorded by the same observer. RESULTS: Demographics were similar. Bloodstaining occurred in 21% of patients in Group A (n = 63) vs 13% in Group B (n = 63; P = 0.23); the incidence of sore throat was identical (19%). Group A experienced more hoarseness (22% vs 9%; P = 0.05). Overall airway complications did not differ between groups (19% vs 11%; P = 0.21). CONCLUSION: We conclude that removal of the laryngeal mask airway inflated does not reduce the incidence of sore throat, pharyngeal morbidity or airway complications.

Adolescent↗
PubMed2001

Poor man's LMA: achieving adequate ventilation with a poor mask seal.

PURPOSE: This report describes a technique of ventilation prior to laryngoscopy and intubation that proved to be simple, inexpensive and effective for a patient whose airway evaluation suggested difficult mask ventilation. The technique is called Poor Man's LMA. CLINICAL FEATURES: A 60-yr-old male, measuring 170 cm, weighing 117 kg, edentulous and with a full beard, was to undergo uvulopalatopharyngoplasty. After induction of general anesthesia with a hypnotic, analgesic and non-depolarizing muscle relaxant, it was soon determined that mask bag ventilation was difficult due to an inadequate seal between the mask and the patient's full beard. To improve ventilation, an endotracheal tube was placed into the oropharynx, the lips and nose compressed by a colleague in order to prevent gas egress, and effective manual ventilation established by connecting the circle system to the endotracheal tube. Subsequent direct laryngoscopy and intubation were accomplished without incident. CONCLUSION: The patient's clinical features made conventional mask bag ventilation difficult and inadequate. The Poor Man's LMA technique improved oxygenation and ventilation in preparation for intubation. Further investigations on the usefulness of this technique are warranted.

Humans↗
PubMed1999

Bronchoscopic removal of bronchial foreign bodies through the laryngeal mask airway in pediatric patients.

The laryngeal mask airway was used to perform fiberoptic removal of bronchial foreign bodies (peanuts) in two pediatric patients. Laryngeal mask airway offers easy access to the airway, safe respiratory management and direct visualization of the airway during bronchoscopic procedures. Laryngeal mask airway allows the use of larger bronchoscopes than can usually be used for children when bronchoscopy is performed through an endotracheal tube. In each case, the peanuts were removed safely and easily using a Fogarty catheter through the fiberoptic bronchoscope. These cases suggest that laryngeal mask airway is useful in maintaining a secure airway during the removal of bronchial foreign bodies in children.

Bronchi↗
PubMed2002

[Laryngeal mask perforation: complication of jugular vein cannulation in a newborn].

This case report describes the perforation of a laryngeal mask during central venous cannulation of the internal jugular vein in a 2000 g, formerly preterm infant. The procedure was undertaken with the patient under general anaesthesia with a laryngeal mask and spontaneous breathing. As a result of the infant's clinical status, multiple needle insertions were required to obtain venous access. The needle was inadvertently advanced to the retropharynx and perforated the air-filled part of the laryngeal mask. Ventilation parameters remained stable. The laryngeal mask causes anatomical alterations of cervical structures in the newborn and therefore its use for the airway management during jugular vein cannulation appears to be limited.

Anesthesia, Inhalation↗
PubMed1994

[The laryngeal mask as an instrument].

The laryngeal mask (LM) was developed by A. Brain to overcome the disadvantages of the face mask (impractical) and the tracheal tube (invasive). Today this new instrument is applied on a broad scale in Great Britain and with growing interest in continental Europe. The laryngeal mask comes in five sizes to fit five different age groups. The blindly applied technique of positioning the LM can be easily learned. Spontaneous or artificial ventilation is possible if the LM is in the correct position. Mechanical ventilation may lead to the insufflation of air into the stomach. Therefore, ventilatory peak pressure should not exceed 20-25 cm H2O and ventilation must be closely monitored. The risk of aspiration can be avoided by the proper selection of patients. The LM may be used with different anaesthetic techniques; muscle relaxant drugs are not mandatory. The authors have applied this mask more than 300 times, and this new instrument obviously has potential for different clinical indications. The LM may be applied for short surgical interventions in all age groups except premature infants. Complications such as regurgitation, aspiration and laryngospasm can be avoided by the awareness of the anaesthetist and by an adjusted deep plane of anaesthesia. Apart from anaesthesia, the LM can be used for bronchoscopy in children, for difficult intubations and as a preliminary airway in cases of resuscitation. Two studies performed in Great Britain have evaluated the LM for resuscitation. The investigations should be confirmed in German-speaking countries.

Humans↗
PubMed2006

Non-invasive ventilation in chronic obstructive pulmonary disease patients: helmet versus facial mask.

RATIONALE: The helmet is a new interface with the potential of increasing the success rate of non-invasive ventilation by improving tolerance. OBJECTIVES: To perform a physiological comparison between the helmet and the conventional facial mask in delivering non-invasive ventilation in hypercapnic patients with chronic obstructive pulmonary disease. METHODS: Prospective, controlled, randomized study with cross-over design. In 10 patients we evaluated gas exchange, inspiratory effort, patient-ventilator synchrony and patient tolerance after 30 min of non-invasive ventilation delivered either by helmet or facial mask; both trials were preceded by periods of spontaneous unassisted breathing. MEASUREMENTS: Arterial blood gases, inspiratory effort, duration of diaphragm contraction and ventilator assistance, effort-to-support delays (at the beginning and at the end of inspiration), number of ineffective efforts, and patient comfort. MAIN RESULTS: Non-invasive ventilation improved gas exchange (p<0.05) and inspiratory effort (p<0.01) with both interfaces. The helmet, however, was less efficient than the mask in reducing inspiratory effort (p<0.05) and worsened the patient-ventilator synchrony, as indicated by the longer delays to trigger on (p<0.05) and cycle off (p<0.05) the mechanical assistance and by the number of ineffective efforts (p<0.005). Patient comfort was no different with the two interfaces. CONCLUSIONS: Helmet and facial mask were equally tolerated and both were effective in ameliorating gas exchange and decreasing inspiratory effort. The helmet, however, was less efficient in decreasing inspiratory effort and worsened the patient-ventilator interaction.

Aged↗
PubMed2006

Masking visual stimuli by transcranial magnetic stimulation.

Transcranial magnetic stimulation (TMS) applied over the occipital pole can suppress visual perception. Since its first description in 1989 by Amassian et al., this technique has widely been used to investigate visual processing at the cortical level. This article presents a review of experiments masking visual stimuli by TMS. The psychophysical characterization of TMS masking, the dependence on stimulus onset asynchrony between visual stimulus and TMS pulse, and the topography of masking within the visual field are considered. The relation between visual masking and the generation of phosphenes is discussed as well as the underlying physiological mechanisms.

Evoked Potentials, Visual↗
PubMed2005

Temporal masking in electric hearing.

Temporal masking can be defined as the detection threshold of a brief signal as a function of the signal delay in a relatively long masker. The temporal masking pattern in normal acoustic hearing reveals temporal edge enhancement in which the signal detection threshold is greater near the masker onset than in the steady-state portion. Both peripheral and central mechanisms appear to underlie temporal edge enhancement, but their relative contributions remain elusive. Cochlear implants bypass cochlear mechanical processing and stimulate the auditory nerve directly, thereby providing a unique opportunity to separate the peripheral mechanisms from the central mechanisms. Here, we systematically measured temporal masking in electric hearing by examining whether a brief signal was harder to detect at the onset than in the steady-state portion of a long masker (the "overshoot" effect). The signal and the masker were presented (1) either to the same electrode or to different electrodes, (2) at the same stimulation or different rates, and (3) in a simultaneous or an interleaved fashion. A consistent pattern of results was observed, depending on the stimulus configuration between the signal and the masker. Simultaneous stimulation at the same rate and with the same electrode produced no difference in sensitivity between the onset and the steady-state conditions, but interleaved stimulation at different rates or with different electrodes produced a significant difference. Unlike acoustic hearing, high masker levels produced an overshoot effect, and low masker levels produced an undershoot effect. Although the present results are consistent with the "on-frequency vs. off-frequency" hypothesis for the overshoot effect, results also suggest a central "same vs. different" mechanism underlying temporal masking. These results have practical implications for improving cochlear implant design.

Acoustic Stimulation↗
PubMed1982

Auditory brain stem potentials evoked by clicks in notch-filtered masking noise.

Auditory brain stem evoked potentials (ABEPs) were recorded in response to wide-band clicks in notch-filtered masking noise. Notches (1/2 octave wide, 96 dB/octave slopes) were centered on the audiometric frequencies. Without the notches, masking noise intensity was adjusted to obliterate ABEPs. Intensity series, with both clicks and masking noise attenuated by the same 10 dB steps, were obtained for clicks masked by notched noise, in addition to unmasked clicks. Absolute latencies and interpeak latency differences of ABEPs to clicks in notched noise did not change with notch frequency. Absolute latencies were longer for ABEPs to clicks with notched noise than to unmasked clicks. For all stimuli, latencies were prolonged when stimulus intensity decreased. The findings suggest that ABEPs to clicks in notched noise are initiated by low threshold cochlear activation which may account for the independence of component latency from 'travelling wave' propagation time. These potentials may be representative of only one subset of the constituents of ABEPs to wide-bank unmasked clicks. The clinical application of these potentials must await elucidation of their relevance to the process of hearing.

Acoustic Stimulation↗
PubMed1987

Response enhancement and reduction of the auditory brain-stem response in a forward-masking paradigm.

Alterations in the probe evoked auditory brain-stem response (ABR) were evaluated in 15 normal-hearing subjects using several stimulus configurations in a tone-on-tone forward-masking paradigm. The stimulus parameters manipulated in the study included: masker frequency; relative intensity of the masker; overall intensity of the masker-probe pair; and masker rise-fall time. Latency increases for waves III and V and an amplitude reduction for wave III were observed under some stimulus conditions. These changes were interpreted in terms of partial forward-masking effects. The masking effects were shown: to be maximal for masker frequencies in close proximity to the probe; to increase with increasing level of masker; to be independent of the overall level of the masker-probe pair; and, to decrease with increasing rise-fall time of the masker. Collectively, the forward-masking effects were interpreted as peripheral in origin, although, an additional brain-stem locus was not ruled out. In contrast, the same stimuli which increased wave III and V latencies and reduced wave III amplitude produced a robust amplitude increment in wave V which was termed enhancement. Wave V enhancement was shown: to be maximal for masker frequencies in close proximity to the probe; to decrease with increasing masker level; and, to decrease with faster rise-fall times of the masker. The processes mediating wave V enhancement are not clear, however, it was concluded that wave V enhancement probably reflects the resultant of a complex central neuronal interaction, presumably in the vicinity of the wave V generator(s).

Acoustic Stimulation↗
PubMed1982

Hemispheric asymmetry for face recognition: some effects of visual masking, hemiretinal stimulation and learning task.

Five overlearned target faces were presented hemiretinally and identified by name on the recognition trials (Experiment 1). A post-exposure pattern mask was projected by the opposite eye to either the same (MASK) or the opposite (DISTRACTOR) hemisphere as the targets. Target exposure durations yielding 50% accuracy showed significant left-hemisphere and temporal hemiretinal superiorities in DISTRACTOR, but not in MASK. In Experiment 2, recognition accuracy for six faces at a constant exposure duration, under DISTRACTOR and no-mask control conditions, replicated the left-hemisphere advantage. Manipulation of the information accompanying targets during the initial learning task, to encourage either "social" or "physical" encoding of the faces, produced a "crossover" pattern of contrasting hemispheric asymmetries under the two encoding conditions. The overall results suggest that within this design, face recognition can be accomplished in three different ways, producing either no hemispheric asymmetry, undirectional asymmetry, or complex, contrasting asymmetries. These effects appear to have different functional loci. Hemiretinal differences and individual differences in encoding strategies also contributed to complex patterns of hemispheric asymmetry.

Adult↗
PubMed1983

Feature similarity and laterality effects in visual masking.

Observers attempted to recognize single letters presented to the left or right visual field when preceded or followed by a masking stimulus. When the masking stimulus contained features identical to those of the target letter, there was a left visual field (right hemisphere) advantage for target recognition. When the target and mask contained extremely different features, the opposite visual field advantage was obtained. Implications are discussed for models of hemispheric asymmetry and for interpreting visual laterality studies that use masks to reduce the overall level of performance.

Adult↗