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At least 127 records · Page 7Linked to original sources
PubMed2006

[Use of the size 3 ProSeal laryngeal mask airway in children. Results of a randomized crossover investigation with the Classic laryngeal mask airway].

BACKGROUND: The low-pressure airway seal of the Classic laryngeal mask airway (CLMA) can be inadequate for positive pressure ventilation (PPV) in children. The ProSeal laryngeal mask airway (PLMA) forms a more effective seal of the airway than the CLMA and facilitates gastric tube placement in adults. The size 3 PLMA can be used in adults and children. METHODS: The CLMA and PLMA were studied in random order -- crossover -- in 30 anaesthetized, non-paralysed children (average age 10.6 years, average body weight 39 kg). Airway leak pressure, maximum tidal volume, ease of insertion, quality of initial airway and fiberoptic position were determined. Gastric tube placement was assessed for the PLMA. RESULTS: The mean airway leak pressure in neutral head position (27.0 vs. 16.8 cm H(2)O), maximum flexion (38.3 vs. 26.2 cm H(2)O) and maximum extension (21.1 vs. 14.2 cm H(2)O) as well as the mean maximum tidal volume (1432 vs. 1062 ml) were significantly higher (p<0.001) for the PLMA. Air insufflation into the stomach occurred with the CLMA but not with the PLMA. Gastric tube placement was possible in all patients. CONCLUSIONS: The high reliability of g-tube placement and the significantly increased airway leak pressure seem to make the size 3 PLMA a more suitable device for PPV in children than the same size CLMA.

Adolescent↗
PubMed1999

[Is the laryngeal mask a minimally invasive instrument for securing the airway? Supplementary remarks on the paper "Injures and dangers in the use of the laryngeal mask" by V. Hempel, Anaesthesist (1999)48:399-402].

Minor laryngopharyngeal complaints following anaesthesia considerably determine postoperative patient comfort. They cannot be eliminated but reduced by experience and careful preparation and insertion technique. The incidence of minor laryngopharyngeal symptoms following the use of the laryngeal mask airway is similar to that following endotracheal intubation. However, there seems to be a distinct pattern of complaints: discomfort with swallowing is more frequent after LMA, whereas dysphonia is more often observed following endotracheal intubation. The significance of LMA cuff pressures in the pathogenesis of postoperative throat complaints remains unclear. There is sound evidence that cuff pressure is not a representative measure for the effective pressure load upon the pharyngeal mucosa. Measurement of cuff pressure is not obligatory, instead reduction of cuff volume to a "just seal" situation seems to be a reasonable approach. The laryngeal mask airway has definitely changed anaesthesiology airway management. Whether this is due to its supposedly less invasiveness compared to endotracheal intubation has not been proven by scientific investigations.

Humans↗
PubMed1993

A comparison of bag mask and mouth mask ventilation in anaesthetised patients.

Anaesthetic residents used bag valve mask (BVM) or mouth mask (MM) ventilation, both with an O2 flow of 15 l min-1 to ventilate 30 ASA I or II anaesthetised patients for 4 min prior to endotracheal intubation. Mean nasopharyngeal O2 was higher with BVM (BVM 95% (S.D. 3%) MM 54% (S.D. 12%)). End tidal CO2 (ETCO2) was similar in both groups (ETCO2% at 4 min: BVM 4.65 (S.D. 0.84) MM 4.53 (S.D. 0.54)) but respiratory rate was faster with BVM (BVM 17 min-1 (S.D. 5) MM 12 min-1 (S.D. 4)). Peak (Paw) and mean (Paw) airway pressures were higher with MM and MM produced significant expiratory pressure [cmH2O: BVM Paw 16.7 (S.D. 5.3) Paw 4.2 (S.D. 2.1) MM: Paw 20.9 (S.D. 5.2) Paw 7.8 (S.D. 2.1)) minimum expiratory pressure: MM 2.4 (S.D. 1.1) BVM 0.2 (S.D. 0.4). Gastric insufflation was detected in two MM and two BVM patients. This tended to be more severe with MM ventilation. Although MM ventilation has some important disadvantages it can be used effectively by resuscitators with little or no experience in its use.

Adult↗
PubMed2005

The effect of a steep high-frequency hearing loss on growth-of-masking functions in simultaneous masking for f(m)<f(s).

In normal-hearing subjects, the slope of the growth-of-masking (GOM) function obtained in simultaneous masking when the masker frequency (f(m)) is much less than the signal frequency (f(s)) often changes from a value near 2.0 to a value near 1.0 at high levels. The purpose of the present study was to evaluate whether this change in slope reflects a basal shift in the peak of the signal's basilar-membrane vibration pattern. To discourage the use of basally shifted peak excitation, GOM functions were obtained in seven subjects with a precipitously sloping high-frequency hearing loss. The signal was located at the normal-hearing edge of the loss, and the masker was located 3 equivalent rectangular bandwidths below f(s). In addition, GOM functions for an f(s) of 2000 Hz were obtained in four subjects with normal hearing, either "in quiet" or in the presence of a restrictor tone with a frequency of 2400 or 2600 Hz and a level of 90 dB SPL. Overall, the results generally are not consistent with the change in slope at high levels being due to a basal shift in the peak of the signal's basilar-membrane vibration pattern. Instead, the results are consistent with a decrease in compression at high input levels at the place corresponding to f(s).

Acoustic Stimulation↗
PubMed2003

[Airway equipment and its maintenance for a non difficult adult airway management (endotracheal intubation and its alternative: face mask, laryngeal mask airway, laryngeal tube)].

The airway equipment for a non difficult adult airway management are described: endotracheal tubes with a specific discussion on how to inflate the balloon, laryngoscopes and blades, stylets and intubation guides, oral airways, face masks, laryngeal mask airways and laryngeal tubes. Cleaning and disinfections with the maintenance are also discussed for each type of airway management.

Adjuvants, Anesthesia↗
PubMed2006

Comparison of LMA Unique, Ambu laryngeal mask and Soft Seal laryngeal mask during routine surgical procedures.

BACKGROUND AND OBJECTIVE: This study was performed to compare three disposable airway devices, the LMA Unique (LMA-U), the Ambu laryngeal mask (Ambu LM) and the Soft Seal laryngeal mask (Soft Seal LM) for elective general anaesthesia during controlled ventilation in non-paralysed patients. METHODS: One hundred and twenty ASA I-III patients scheduled for routine minor obstetric surgery were randomly allocated to the LMA-U (n = 40), Ambu LM (n = 40) or Soft Seal LM (n = 40) groups, respectively. Patients were comparable with respect to weight and airway characteristics. A size 4 LMA was used in all patients and inserted by a single experienced anaesthesiologist. Oxygenation, overall success rate, insertion time, cuff pressure and resulting airway leak pressure were determined as well as a subjective assessment of handling and the incidence of sore throat, dysphagia and hoarseness. RESULTS: Time of insertion was shortest with the Ambu LM, while failure rates were comparable with the LMA-U, the Ambu LM and the Soft Seal LM (median 19 s; range 8-57 s; success rate 100% vs. 14; 8-35; 97% vs. 20; 12-46; 95%). Insertion was judged 'excellent' in 75% of patients in the LMA-U group, in 70% of patients in Ambu LM group and in 65% of patients in the Soft Seal LM group. There was no difference between devices with respect to postoperative airway morbidity at 6 h or 24 h following surgery. CONCLUSIONS: All three disposable devices were clinically suitable with respect to insertion times, success rates, oxygenation, airway and leak pressures, as well as to subjective handling and postoperative airway morbidity.

Air Pressure↗
PubMed1990

Masking of tone bursts by modulated noise in normal, noise-masked normal, and hearing-impaired listeners.

Threshold of 4.6-ms tone bursts was measured in quiet and in the presence of a 100% sinusoidally amplitude-modulated speech-shaped noise. For the modulated-noise conditions, the onset of the tone burst coincided either with the maximum or the minimum modulator amplitude. The difference in these two masked thresholds provided an indication of the psychoacoustic modulation depth, or the modulation depth preserved within the auditory system. Modulation frequencies spanning the modulation spectrum of speech (2.5 to 20 Hz) were examined. Tone bursts were 500, 1400, and 4000 Hz. Subjects included normal listeners, normal listeners with a hearing loss simulated by high-pass noise, and hearing-impaired listeners having high-frequency sensorineural hearing loss. Normal listeners revealed a psychoacoustic modulation depth of 30-40 dB for the lowest modulation frequencies which decreased to about 15 dB at 20 Hz. The psychoacoustic modulation depth was decreased in the normal listeners with simulated hearing loss and in the hearing-impaired listeners. There was general agreement in the data, however, for the latter two groups of listeners suggesting that the normal listeners with hearing loss simulated by an additional masking noise provided a good representation of the performance of hearing-impaired listeners on this task.

Adult↗
PubMed2002

[A comparison of the Proseal laryngeal mask to the standard laryngeal mask on anesthesized, non-relaxed patients].

It was our goal to compare the Proseal-laryngeal mask airway (PLMA) with the classical laryngeal mask airway (LMA) in a german multicenter trial. Handling of the instruments and application criteria were to be tested. 7 anaesthesia departments were able to take part in this study. 280 patients could be investigated after approval of the ethics committee of the medical faculty of the university of Goettingen. 145 patients received the PLMA and 135 the LMA. The surgical interventions were small to moderate procedures with a duration of at least 20 minutes in the sections general surgery, trauma/orthopedic surgery, urology, vascular surgery, gynecology, ENT-surgery and ophthalmology. There was equivalence of the two instruments PLMA and LMA concerning duration and ease of insertion, endoscopic position check, observations on emergence, potential for injury and some postoperative complaints. This equivalence could be confirmed statistically. Laryngospasm was observed in three, Bronchospasm in two patients with the PLMA, in no one with the LMA. In one case of laryngospasm and another of bronchospasm a mechanism of supraglottic laryngeal stenosis has been involved which may occur in rare instances with the PLMA. This mechanism is due to the double cuff of the PLMA with the instruments proximity to the laryngeal inlet. The seal pressure in both groups differs significantly (p = 0.001). The mean value for the seal pressure was 29,3 +/- 0,21 mbar for the PLMA and 20,9 +/- 0,21 mbar for the LMA. In the PLMA the gastric tube could be positioned with the first attempt in 118 patients, with the second attempt in 17 cases. In 10 patients the gastric tube could not be placed. Contrary to the LMA the tip of the PLMA cuff may be bent in some cases with loss of airway safety and positioning of the gastric tube. The symptoms sore throat and painful swallowing on the first postoperative day were more frequent with LMA application. These differences could be confirmed statistically (sore throat p = 0.01, painful swallowing p = 0.04). They may be explained by the more rigid LMA compared to the PLMA and by the fact that the LMA in this study was older than the PLMA, loosing plasticizer. The drainage tube within the PLMA offers safety from aspiration in patients with no primary aspiration risk, additional reassurance for a correct position and a better stability of the airway. Our data may support a wider indication range for the PLMA compared with the LMA. The PLMA may be applied in laparoscopies and lower abdominal surgical interventions. Careful clinical observation will show, if the minimal invasiveness of the PLMA offers an advantage for these patients. The PLMA should not be applied in patients with increased aspiration risk.

Adolescent↗
PubMed1985

Face seal leakage of half masks and surgical masks.

The efficiency and face seal leakage characteristics of two half masks equipped with particle filters or gas filters, and of two surgical masks were studied by means of a test head connected to a breathing machine. Filtration and leakage were studied as a function of particle size over a diameter range of 0.3-10 micron with corn oil aerosol and an optical particle counter. The filtration efficiency of the filter materials was good, over 95%, for particles above 5 micron in diameter but great variation existed for smaller particles. The face seal leakage was manifested as decreased efficiency for large particles and also for total mass, while the particles in the micrometer range contained the major part of the test aerosol mass. The particle number efficiency diagrams obtained can be used both in filter material studies and in leak detection of valves or filter housings.

Aerosols↗
PubMed1993

Resistance to constant air flow imposed by the standard laryngeal mask, the reinforced laryngeal mask and RAE tracheal tubes.

The reinforced laryngeal mask airway (RLMA) has been introduced recently for head and neck surgery. Its resistance to constant air flow has been measured and compared with that of the standard laryngeal mask airway (LMA). The RLMA resistance has also been compared with that imposed by the standard oral Ring-Adair-Elwyn (RAE) tube of a corresponding size for a given patient. The resistance to gas flow of the new RLMA was approximately three to five times that of the LMA at two flow rates (0.5 and 1.0 litre s-1). The resistance of the RLMA 4 was intermediate between that of RAE tubes sizes 8 and 9 mm, and that of RLMA 2 intermediate between that of RAE tubes sizes 5 and 6 mm.

Air Pressure↗
PubMed2003

Comparison of the standard laryngeal mask airway and the ProSeal laryngeal mask airway in obese patients.

BACKGROUND: The ProSeal laryngeal mask airway (PLMA) may have advantages over the laryngeal mask airway (LMA) in obese patients. We tested this hypothesis in a clinical setting. METHODS: Sixty obese patients (BMI >30) were randomized to receive mechanical ventilation (tidal volume 7 ml kg(-1), PEEP 10 cm H(2)O), through either the PLMA or the LMA. A gastric tube was used in all patients. Cuff pressure was set at 60 cm H(2)O and increased progressively until excessive leak occurred. The incidence of sore throat was assessed at recovery and after 1 week. RESULTS: The mean leak fraction was 6.1 (SD 2.9)% with the LMA and 6.4 (3.5)% with the PLMA (P=0.721). With the PLMA, with no sign of ventilation problems, the drainage tube was not patent in three patients. The cuff pressure was >100 cm H(2)O in 38% of the LMA group and 7% of the PLMA group (P=0.05). The incidence of sore throat was similar in both groups and it was similarly scored in the recovery room and 1 week after surgery. CONCLUSIONS: Both the PLMA and the LMA can be used for mechanical ventilation of obese patients. The patency of the PLMA drainage tube needs to be checked constantly even when an optimal airtight seal is present. In obese patients the LMA requires a greater cuff pressure than the PLMA, but sore throat is not related to the cuff pressure. Sore throat assessment in the recovery room appears as reliable as assessment later.

Adult↗
PubMed2000

Comparison of laryngeal mask and intubating laryngeal mask insertion by the naïve intubator.

Seventy-five inexperienced participants were timed inserting the laryngeal mask airway (LMA) and the intubating laryngeal mask (ILM) in one of five cadavers. Adequacy of ventilation was assessed on a three-point scale depending on chest expansion and air leak. Participants were also asked to intubate the trachea via the ILM. The ILM was inserted faster than the LMA (P < 0.05) with a greater proportion achieving adequate ventilation after their first attempt (P < 0.05). Tracheal intubation via the ILM was completed successfully by 67% (52 of 75) of participants. In a questionnaire, participants stated that the ILM was easier to use and the preferred device in an emergency. The results suggest that inexperienced practitioners should use the ILM rather than the LMA for emergency ventilation.

Cadaver↗
PubMed2005

Airway rescue in acute upper airway obstruction using a ProSeal Laryngeal mask airway and an Aintree catheter: a review of the ProSeal Laryngeal mask airway in the management of the difficult airway.

We report the successful use of a ProSeal Laryngeal mask airway (PLMA) to rescue the airway when emergency tracheal intubation and ventilation of the lungs were impossible after haemorrhage into the neck following carotid endarterectomy, despite evacuation of the clot. The airway was re-established after placement of a PLMA. Fibreoptic examination of the airway revealed severe supraglottic swelling compromising airway patency. An Aintree catheter was placed in the trachea under fibreoptic guidance and a tracheal tube railroaded over this. The use of the PLMA in seven cases of difficult airway management and 11 cases of airway rescue is reviewed. Use of the PLMA was associated with high levels of success, often rescuing the airway when other techniques had failed. No complications of use of the PLMA were reported in these cases. The PLMA appears to be a useful device to assist in management of the difficult airway and for airway rescue. Potential advantages over the classic laryngeal mask airway include improved airway seal and reduced risk of aspiration. The gum elastic bougie-guided insertion technique is recommended when the PLMA is used for airway rescue.

Acute Disease↗
PubMed2006

Binaural detection of 500-Hz tones in broadband and in narrowband masking noise: effects of signal/masker duration and forward masking fringes.

NoSpi thresholds for a 500-Hz tonal signal were measured with broadband and with narrowband maskers using a single-interval adaptive matrix procedure [C. Kaernbach, J Acoust. Soc. Am. 88, 2645-2655 (1990)]. The purpose of the study was to investigate and to account for the effects on thresholds of varying the durations of the signals and maskers and the durations of forward masking fringes that preceded the occurrence of signal-plus-noise. For detection in both broadband and narrowband noise, the addition of brief forward fringes of masking noise resulted in elevations in threshold for the shortest signal durations. Longer forward fringes led to larger decreases in threshold when the masker was broadband as compared to when the masker was narrowband. The complex patterning of the data was explained by the operation of: (1) "predetection" temporal integration associated with peripheral auditory filtering; (2) duration-dependent, across-frequency influences that differentially affect broadband and narrowband NoSpi thresholds, (3) "post-detection" temporal integration associated with the central binaural mechanism, and (4) consideration of the detection thresholds in terms of changes in interaural correlation rather than in terms of signal level or signal-to-noise ratio, per se.

Acoustic Stimulation↗
PubMed1988

Speech masking. II: Simultaneous masking thresholds under "naturalistic" listening conditions.

This article investigates the role of listening conditions in determining thresholds for probe tones masked by natural speech. These thresholds are of interest because they are a sensitive probe of the activity profile, or spectrum, of sounds such as speech in the auditory system. Most human performance tests are carried out under highly artificial listening conditions, which may not reflect how people listen to speech in common listening environments. In this study, reference conditions (similar to minimal uncertainty listening conditions used in many performance tests) were compared to a "naturalistic" listening condition and to another, intermediate, condition. In the naturalistic listening condition, listeners did not know the frequency or the position of probe tones; additionally, they were required to attend to the semantic content of sentences. In the reference condition, listeners knew the frequency and position of probe tones masked by single syllables. Average thresholds were elevated by 4 dB in the naturalistic listening condition with respect to the reference condition, and thresholds tended to be elevated more for higher-frequency probe tones. The results provide previously unknown information about the resolution of speech sounds in the auditory system during speech comprehension.

Adolescent↗
PubMed1995

Some factors influencing comodulation masking release and across-channel masking.

The purpose of this study was to determine whether comodulation masking release (CMR) and across-channel masking (ACM) are by-products of a similar across-channel mechanism. This was addressed by examining how the two are affected by stimulus manipulations expected to influence their magnitude. Subjects were required to detect a 1000-Hz signal in the presence of a masker that consisted of a 1000-Hz (on-frequency) component alone or that component and up to six flanking components (500, 600, 700, 1300, 1400, and 1500 Hz). The on-frequency and flanking components typically were sinusoidally amplitude modulated at 10 Hz, although not necessarily in phase with one another. In experiment 1, the amount of CMR and ACM was highly influenced by whether the signal consisted of one or three 50-ms tone bursts; in fact, ACM was only observed when the signal was a train of three 50-ms tone bursts. In experiments 2 and 3, CMR tended to increase as the modulation depth or the number of flanking components increased, whereas ACM was relatively unaffected by these manipulations. In addition, ACM was observed under dichotic situations, whereas CMR was not. Taken together, the results suggest that ACM and CMR may be mediated by different mechanisms.

Adult↗
PubMed2004

The laryngeal mask airway Unique versus the Soft Seal laryngeal mask: a randomized, crossover study in paralyzed, anesthetized patients.

We tested the hypothesis that ease of insertion, oropharyngeal leak pressure, fiberoptic position, ease of ventilation, and mucosal trauma are different for the Soft Seal laryngeal mask airway (SSLM) and the laryngeal mask airway Unique (LMA-U). Ninety paralyzed, anesthetized adult patients (ASA I-II; 18-80 yr old) were studied. Both devices were inserted into each patient in random order. Oropharyngeal leak pressure and fiberoptic position were determined during cuff inflation from 0-40 mL in 10-mL increments and at an intracuff pressure of 60 cm H(2)O. Ease of ventilation was determined by controlling ventilation for 10 min at 8 and 12-mL/kg tidal volume and recording hemoglobin oxygen saturation, end-tidal CO(2), leak fraction, peak airway pressure, and the presence or absence of gastric insufflation. Mucosal trauma was determined by examining the first randomized device for the presence of visible and occult blood. Insertion time was shorter (P = 0.0001) and fewer attempts were required (P = 0.005) for the LMA-U. There were no failed uses of either device. Oropharyngeal leak pressures were similar, but fiberoptic position was superior with the LMA-U (P < or = 0.0003). There were no differences in hemoglobin oxygen saturation, end-tidal CO(2), leak fraction, or peak airway pressure at either tidal volume. Gastric insufflation was not detected in either group at either tidal volume. The frequency of visible (P = 0.009) and occult blood (P = 0.0001) was less with the LMA-U. We conclude that the LMA-U is superior to the SSLM in terms of ease of insertion, fiberoptic position, and mucosal trauma, but similar in terms of oropharyngeal leak pressure and ease of ventilation.

Adult↗
PubMed2006

The size 1(1/2) ProSeal laryngeal mask airway in infants: a randomized, crossover investigation with the Classic laryngeal mask airway.

Many problems with the Classic laryngeal mask airway (CLMA) in infants are believed to be related to its inadequate cuff design. One of the main limitations of the CLMA is that the resulting low-pressure seal can be inadequate for positive pressure ventilation (PPV). The ProSeal LMA (PLMA), a new laryngeal mask airway with a modified cuff, has been shown to form a more effective seal than the CLMA in children. The first infant size PLMA, size 1(1/2), became available recently. We studied 30 anesthetized, nonparalyzed infants aged 15 mo (2-30 mo) and weighing 9 kg (5-12 kg). The CLMA and PLMA were inserted in random order into each patient. Airway leak pressure and maximum tidal volume were measured. Ease of insertion, quality of initial airway, and fiberoptic position were also determined. Gastric tube placement was assessed for the PLMA. The mean airway leak pressure in neutral head position (26.7 versus 18.9 cm H2O), maximum flexion (35.6 versus 28.2 cm H2O), and the mean maximum tidal volume (312 versus 260 mL) were significantly higher for the PLMA (P < 0.01). Air entered the stomach in eight patients with the CLMA but did not with the PLMA. Gastric tube placement was possible in all but one patient. In three patients, the use of the PLMA led to some degree of clinically relevant compression of the larynx. The size 1(1/2) PLMA seems to be a more suitable device for airway maintenance in infants than the same size CLMA. The ability to insert a gastric tube at the same time, and a significantly higher airway leak pressure than with the CLMA, may have important implications for its use for PPV in infants.

Anesthesia↗