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At least 1,315 records · Page 73Linked to original sources
PubMed1999

Epileptiform electroencephalogram during mask induction of anesthesia with sevoflurane.

BACKGROUND: Sevoflurane is suggested as a suitable anesthetic agent for mask induction in adults. The authors recently found that hyperventilation during sevoflurane-nitrous oxide-oxygen mask induction is associated with cardiovascular hyperdynamic response. We tested the hypothesis that the hyperdynamic response can be explained by electroencephalography (EEG) findings. METHODS: Thirty women were randomly allocated to receive sevoflurane-nitrous oxygen-oxygen mask induction using a single-breath method, followed by either spontaneous breathing (n = 15) or controlled hyperventilation (n = 15) for 6 min. EEG was recorded. Blood pressure and heart rate were recorded at 1-min intervals. RESULTS: Epileptiform EEG activity (spikes or polyspikes) was seen in all patients with controlled hyperventilation, and in seven patients with spontaneous breathing (P < 0.01). Jerking movements were seen in three patients with controlled hyperventilation. In the controlled hyperventilation group, heart rate increased 54% from baseline at 4 min after induction (P < 0.001). Mean arterial pressure increased 17% (P < 0.05), peaking at 3 min. In the spontaneous breathing group, heart rate showed no change, and mean arterial pressure decreased by 14% (P < 0.01) at 6 min. Heart rate and mean arterial pressure differed significantly between the groups from 2 min after beginning of the induction to the end of the trial. An increase in heart rate of more than 30% from baseline always was associated with epileptiform EEG activity. CONCLUSIONS: Sevoflurane mask induction elicits epileptiform EEG patterns. These are associated with an increase in heart rate in patients with controlled hyperventilation and also during spontaneous breathing of sevoflurane.

Adult↗
PubMed2000

Prediction of difficult mask ventilation.

BACKGROUND: Maintenance of airway patency and oxygenation are the main objectives of face-mask ventilation. Because the incidence of difficult mask ventilation (DMV) and the factors associated with it are not well known, we undertook this prospective study. METHODS: Difficult mask ventilation was defined as the inability of an unassisted anesthesiologist to maintain the measured oxygen saturation as measured by pulse oximetry > 92% or to prevent or reverse signs of inadequate ventilation during positive-pressure mask ventilation under general anesthesia. A univariate analysis was performed to identify potential factors predicting DMV, followed by a multivariate analysis, and odds ratio and 95% confidence interval were calculated. RESULTS: A total of 1,502 patients were prospectively included. DMV was reported in 75 patients (5%; 95% confidence interval, 3.9-6.1%), with one case of impossible ventilation. DMV was anticipated by the anesthesiologist in only 13 patients (17% of the DMV cases). Body mass index, age, macroglossia, beard, lack of teeth, history of snoring, increased Mallampati grade, and lower thyromental distance were identified in the univariate analysis as potential DMV risk factors. Using a multivariate analysis, five criteria were recognized as independent factors for a DMV (age older than 55 yr, body mass index > 26 kg/m2, beard, lack of teeth, history of snoring), the presence of two indicating high likelihood of DMV (sensitivity, 0.72; specificity, 0.73). CONCLUSION: In a general adult population, DMV was reported in 5% of the patients. A simple DMV risk score was established. Being able to more accurately predict DMV may improve the safety of airway management.

Adult↗
PubMed2001

Pharyngolaryngeal morbidity with the laryngeal mask airway in spontaneously breathing patients: does size matter?

BACKGROUND: Currently, the manufacturer of the laryngeal mask airway (LMA; Laryngeal Mask Company, Ltd., Northfield End, Henley on Thames, Oxon, United Kingdom) recommends using as large a mask size as possible. The aim of this study was to compare the incidence of pharyngolaryngeal morbidity after the use of a large (size 5 in males and size 4 in females) or small (size 4 in males and size 3 in females) LMA in spontaneously breathing patients. METHODS: A total of 258 male and female patients were randomly assigned to insertion of a large or small LMA while breathing spontaneously during general anesthesia. After insertion of the LMA, a "just-seal" cuff pressure was obtained, and intracuff pressure was measured at 10-min intervals until just before removal of the LMA. The 2- and 24-h incidence of postoperative sore throat, pain, hoarseness, dysphagia, and nausea and vomiting was assessed. Complications after LMA removal, including body movement, coughing, retching, regurgitation, vomiting, biting on the LMA, bronchospasm, laryngospasm, or the presence of blood on the LMA, were recorded. RESULTS: The use of a large LMA was associated with a higher incidence of sore throat in both sexes (20% vs. 7% in men, 21% vs. 5% in women; P < 0.05) and a higher incidence of hoarseness in male patients at 2 h postoperatively (21% vs. 9%, P < 0.05). There was a higher incidence of sore throat in male patients at 24 h postoperatively with the use of a large LMA (26% vs. 12%, P < 0.05). There was no difference in the incidence of complications of LMA removal orother pharyngolaryngeal morbidity, such as difficulty swallowing, drinking, and eating, or nausea and vomiting, between male or female groups at any time period with the use of a large LMA. CONCLUSIONS: Selection of a small laryngeal mask airway (size 4) in spontaneously breathing male patients may be more appropriate to limit the occurrence of sore throat on the first postoperative day. All patients had a fourfold increased risk of developing sore throat when a large LMA was used.

Adult↗
PubMed2004

A comparison of sex- and weight-based ProSeal laryngeal mask size selection criteria: a randomized study of healthy anesthetized, paralyzed adult patients.

BACKGROUND: The authors compared the manufacturer's weight-based formula (size 3 for weight < 50 kg, size 4 for weight 50-70 kg, and size 5 for weight > 70 kg) with a sex-based formula (size 4 for women and size 5 for men) for selecting the appropriate size of ProSeal laryngeal mask airway. METHODS: Two hundred thirty-seven healthy, anesthetized, paralyzed adult patients (American Society of Anesthesiologists physical status I or II; age, 18-80 yr) were randomly allocated for weight- or sex-based size selection. An experienced user inserted the ProSeal laryngeal mask airway with the digital technique. The following were compared: ease of insertion, oropharyngeal leak pressure, ease of ventilation, gas exchange, location of gas leak, anatomic position, mucosal injury, and postoperative pharyngolaryngeal problems. Intraoperative and postoperative data collection were unblinded and blinded, respectively. RESULTS: Ease of insertion, anatomic position, gas exchange, mucosal injury, and postoperative pharyngolaryngeal problems were similar between groups. For the sex-based group, larger ProSeal laryngeal mask airways were selected more frequently (P < 0.0001), oropharyngeal leak pressure (P = 0.02) was higher, leak volume (P = 0.004) and leak fraction (P = 0.007) were lower, and oropharyngeal leaks (P = 0.03) were detected less frequently. CONCLUSION: Size selection for the ProSeal laryngeal mask airway is equally effective using the manufacturer's weight-based formula or the sex-based formula in healthy, anesthetized, paralyzed adult patients, but leakage of small volumes of air from the mouth occurs less frequently with the sex-based formula.

Adolescent↗
PubMed1990

Continuous positive airway pressure by face mask in Pneumocystis carinii pneumonia.

We used continuous positive airway pressure (CPAP) by face mask to treat 18 AIDS patients with Pneumocystis carinii pneumonia (PCP) who were in hypoxic respiratory failure. Candidates for mask CPAP were conscious, not hypercarbic, and able to protect their airway on ICU admission. Treatment was effective and well tolerated. Mean Po2 rose from 62 to 158 torr, respiratory rate decreased from 51 to 32 breath/min, and Pco2 was unchanged. Mean duration of treatment was 4.5 days. Only one patient developed a pneumothorax; there were no other major complications. Hospital mortality was 55%. CPAP by face mask allows speech and permits discussion of therapeutic limits. We present our protocol for using CPAP by face mask and conclude that CPAP is effective supportive therapy in hypoxic respiratory failure complicating PCP and AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed2001

Bag-mask ventilation as a temporizing measure in acute infectious upper-airway obstruction: does it really work?

Jaw-thrust and bag-mask ventilation usually provide adequate oxygenation in patients with acute infectious upper-airway obstruction (AIUAO). It is the treatment of choice for patients on the way to hospital or in an emergency department until definitive stabilization is achieved with available resources. We report three fatal case studies showing ineffective bag-mask ventilation in AIUAO that raise concerns over this treatment. Case 1 is a 4-year-old patient with epiglottitis who suffered complete obstruction during transport to the hospital. Case 2 is a 3-year-old patient with epiglottitis who suffered complete obstruction during transport to the hospital. Case 3 is a 3-year-old child with viral laryngotracheitis and respiratory arrest just after the admission. Should the approach of bag-mask ventilation in AIUAO change to ventilate patients in the prone position? This approach offers two advantages. First, gravity helps the epiglottis fall forward, reducing the airway obstructions. Second, if the patient vomits during ventilation, the vomit will fall to the floor. During bag-mask ventilation in patients with severe partial airway obstruction, ventilation pressure is high. Gastric inflation may occur and rapidly distend the stomach. This gastric distension interferes with ventilation by elevating the diaphragm, resulting in a decreased lung volume. Cricoid pressure could prevent gastric distension in these instances and should be recommended.

Airway Obstruction↗
PubMed1994

Ocular barotrauma caused by mask squeeze during a scuba dive.

I describe the case of a 25-year-old man who, after a scuba dive, had ocular barotrauma caused by mask squeeze. As in most cases, the condition occurred because the patient failed to exhale into the mask during descent to equalize the pressure within the mask. Although alarming in appearance, the condition is generally mild and self-limited. Patients should be instructed in the proper technique of mask clearing before they return to diving to prevent a recurrence.

Adult↗
PubMedDate not supplied

Computerized manufacturing of transparent face masks for the treatment of facial scarring.

In this work an integrated system of computer-aided design and computer-aided manufacturing specifically designed to fabricate affordable transparent face masks is discussed. FaceScan, a custom-designed software system, integrates shape capture, mask design, and pattern fabrication. The software controls a linear scan noncontact laser imager for facial topography acquisition and a milling machine for pattern fabrication. Compared with conventional methods of mask fabrication, this system is faster, more accurate, and less stressful for the patient and allows for greater control of the finished product. Masks for two subjects have been successfully fabricated using this system.

Burns↗
PubMed2005

A diagnostic test for Ménière's Disease and Cochlear Hydrops: impaired high-pass noise masking of auditory brainstem responses.

HYPOTHESIS: Endolymphatic hydrops in patients diagnosed with Ménière's disease causes changes in the response properties of the basilar membrane that lead to impaired high-pass noise masking of auditory brainstem responses to clicks. BACKGROUND: Ménière's disease is defined as the idiopathic syndrome of endolymphatic (cochlear) hydrops, which is an abnormal increase in the volume of cochlear fluid (endolymph) in the inner ear. Accurate detection and diagnosis are important but difficult because of the lack of sufficiently sensitive tests. METHODS: Two populations were compared: (1) 38 non-Ménière's normal-hearing subjects; and (2) 23 patients who, at the time of testing, continued to have at least three of the four hallmark symptoms (i.e., tinnitus, vertigo, fluctuating hearing loss, and fullness) used in the diagnosis of Ménière's disease. Auditory brainstem responses to clicks presented ipsilaterally with masking noise that was high-pass filtered at various frequencies were recorded. RESULTS: In the Ménière's patients, the masking noise is insufficient such that an undermasked Wave V is still present at a latency similar to that of Wave V in the response to the clicks alone. In the control non-Ménière's normal-hearing subjects, this undermasked component was either absent or significantly delayed because of the masking noise. The difference in the delays between these populations is such that the distributions do not overlap, resulting in 100% sensitivity and 100% specificity. CONCLUSION: This test is able to distinguish objectively active Ménière's disease in individuals and may show promise for tracking changes in the severity of the disease caused by progression or treatment.

Acoustic Stimulation↗
PubMed2006

Audiometry with nasally presented masking noise: novel diagnostic method for patulous eustachian tube.

OBJECTIVE: Nasal-noise masking audiometry was developed to assess the acoustic transfer function from the nasopharyngeal cavity to the middle ear via patulous eustachian tube (ET). STUDY DESIGN: Prospective. SETTING: Tertiary referral center. PATIENTS: Twenty-seven ears of 18 patients with patulous ET and 20 ears of 10 healthy subjects with no history of ear disease or complaints of aural symptoms. MAIN OUTCOME MEASURES: Audiometric measurement was conducted with and without masking noise presented in the nasal cavity. RESULTS: The masking effect of nasally presented noise caused elevation of the threshold for the tone presented in the external auditory canal. This threshold elevation was significantly greater, particularly in the lower-frequency region, in ears with patulous ET and was decreased to the normal range after obstructive treatment of the patulous ET. CONCLUSION: Nasal-noise masking audiometry is a simple and effective way to identify patulous ET.

Acoustic Stimulation↗
PubMed2002

Auditory memory for backward masking signals in children with language impairment.

This study was designed to investigate early auditory memory and its possible contribution to an auditory processing deficit shown by some children with language impairment. Ten children with language impairment and 10 age-matched controls participated in a series of simultaneous and backward masking tasks. The same backward masking stimulus was then used to elicit a mismatch negativity response. In the behavioral conditions, children in the language impairment group had significantly higher (poorer) signal thresholds than their nonimpaired controls in backward masking, but their thresholds in simultaneous masking were not significantly different. In the mismatch-negativity conditions, latency was prolonged and the amplitude was diminished in the children with language impairment. Taken together, these psychoacoustic and electrophysiological data suggest that in a group of children with language impairment, underlying the nonsensory language disorder, there is a neurophysiological impairment in auditory memory for complex, nonlinguistic sounds.

Attention↗
PubMed1989

The pressor response and laryngeal mask insertion. A comparison with tracheal intubation.

The pressor response associated with laryngoscopy and tracheal intubation may be harmful to certain patients. The laryngeal mask airway avoids the need for laryngoscopy and allows positive pressure ventilation of the lungs in appropriate patients. This study compared the pressor response of tracheal intubation with that of mask insertion in two groups of 24 and 23 healthy patients respectively. All patients were anaesthetised with thiopentone, nitrous oxide, enflurane and paralysed with atracurium. We have shown a similar, but attenuated pattern of response associated with mask insertion in comparison with laryngoscopy and intubation; significant differences between the groups were evident in arterial diastolic blood pressure immediately after insertion and again 2 minutes later. Use of the laryngeal mask may therefore offer some limited advantages over tracheal intubation in the anaesthetic management of patients where the avoidance of the pressor response is of particular concern.

Adult↗
PubMed1991

Intubation through the laryngeal mask. A technique for unexpected difficult intubation.

Unexpected difficulty with tracheal intubation contributes to anaesthetic mortality. The laryngeal mask can almost always be placed satisfactorily and its position should facilitate blind intubation. A 6-mm cuffed tube will pass through both adult sizes of the mask and this study tested the feasibility of intubation through the mask. The effect of the application of cricoid pressure on the technique was also investigated. Intubation via the laryngeal mask was attempted in 100 routine patients: of the first 50 (group 1, no cricoid pressure), 45 (90%) were successfully intubated. Maintenance of cricoid pressure throughout the manoeuvre (group 2) reduced the success rate significantly to 56% (p less than 0.05). Despite the possibility that cricoid pressure may have to be interrupted momentarily, the ease with which the technique can be learnt, and the immediate availability of the necessary apparatus suggest that it should be considered for inclusion in failed intubation drill.

Adult↗
PubMed1991

The laryngeal mask airway. An unusual complication.

The laryngeal mask airway is an important addition to the anaesthetist's armamentarium, but its use is not without the possibility for misfortune. We encountered an unusual and potentially serious complication. A patient's epiglottis became trapped between the pliable grates in the mask portion of the laryngeal mask and partially obstructed his airway. Should this problem occur and remain unnoticed, in addition to the problem of airway obstruction during the anaesthetic, the oedematous epiglottis could be severely injured upon removal of the laryngeal mask. This, in turn, could result in airway obstruction requiring emergency treatment.

Adult↗
PubMed1991

Intra-ocular pressure changes using the laryngeal mask airway and tracheal tube.

Intra-ocular pressure was measured before and throughout airway establishment with either the laryngeal mask airway or tracheal tube. Similar measurements were made on removal of either airway and the amount of coughing noted in the first minute after removal. There was a significantly smaller increase in intra-ocular pressure (p less than 0.001) using the laryngeal mask airway, both on placement and removal, than with the tracheal tube. Postoperative coughing was significantly reduced using the laryngeal mask airway (p less than 0.001). There was a significantly greater rise in heart rate using the tracheal tube (p less than 0.01) probably related to an increased cardiovascular response. The laryngeal mask airway is recommended as an alternative to tracheal intubation in routine and emergency intra-ocular surgery.

Aged↗
PubMed1992

A comparison of laryngeal mask airway with tracheal tube for intra-ocular ophthalmic surgery.

The use of the laryngeal mask was compared with tracheal intubation in 30 patients who underwent intra-ocular ophthalmic surgery and who received intravenous anaesthesia with propofol. Changes in intra-ocular pressure, heart rate and mean arterial pressure after the insertion of the laryngeal mask airway or the tracheal tube were not significantly different. However, at the end of the procedure, a significantly higher percentage of patients with a tracheal tube coughed, reacted to head movement and suffered breath-holding. In addition, significantly more patients in this group complained of a sore throat (p less than 0.05). During intravenous propofol anaesthesia, the laryngeal mask airway does not offer any advantage over tracheal intubation in the control of intra-ocular pressure for intra-ocular ophthalmic surgery. However, there were fewer complications immediately following surgery in the laryngeal mask group.

Anesthesia, Intravenous↗
PubMed1992

Laryngeal mask and anaesthetic waste gas exposure.

In recent years there has been a growing awareness of the possible hazards caused by anaesthetic gases in operating theatres. The laryngeal mask airway provides an alternative both to tracheal intubation and the face mask although the implications for operating theatre contamination have not been quantified. This paper describes the incidence and magnitude of exposure of theatre personnel to waste anaesthetic gases during laryngeal mask airway anaesthesia. The leakage of anaesthetic gases to the anaesthetist's breathing zone was monitored using a Bruel & Kjaer Multi Gas Monitor, Type 1302 during 50 general anaesthetics employing either spontaneous (n = 24) or controlled (n = 26) ventilation. All patients were anaesthetised with propofol, alfentanil and nitrous oxide. There was no statistically significant association between the amount of anaesthetic gas leakage and ventilation method. The laryngeal mask airway meets occupational safety requirements on nitrous oxide concentrations in the operating theatre environment.

Air Pollutants, Occupational↗
PubMed1993

A comparison of the laryngeal mask airway and Guedel airway, bag and facemask for manual ventilation following formal training.

Ten volunteers, with no previous experience of resuscitation, were formally trained in the use of the laryngeal mask airway and the oropharyngeal airway (Guedel), bag and facemask for manual ventilation of the lungs in 104 fit, anaesthetised adults. They then used both airways in turn. The order of insertion was randomly allocated, and the times taken for insertion were also recorded. Ventilation for each airway was deemed to be successful if an increase in end-tidal carbon dioxide partial pressure did not occur and arterial oxygen saturation remained greater than 90%. Success rates for the laryngeal mask airway and the Guedel airway, bag and facemask were 87% and 43% respectively (p < 0.001) and the average insertion times were 27.4 s (SEM 1.5) and 15.8 s (SEM 0.50) (no significant difference), respectively. The laryngeal mask airway proved to be easier to use for manual ventilation than the Guedel airway, bag and mask for inexperienced personnel who had received a period of formal training in both techniques.

Education, Nursing↗