Comparison of the effects of the laryngeal mask airway and endotracheal intubation on vocal function

The Comparison Between Inhalation and Total Intravenous Anesthesia Effect on Voice With Supraglottic Airway Devices for Short-term Anesthesia

OBJECTIVE

Supraglottic airway devices (SADs) are a good alternative to endotracheal intubation (ETI) in short-term anesthesia applications since they have advantages including easy application, lower cost, enabling spontaneous ventilation. Total intravenous anesthesia (TIVA) and desflurane anesthesia allowing rapid recovery are anesthesia methods to be selected. Inhalation anesthesia by desflurane may cause adverse effects on airway mucosa and vocal cord functions. The aim of the present study was to compare the effect of the chosen anesthesia method on voice in gynecological patients who underwent short-term anesthesia with SADs.

MATERIAL AND METHOD

Seventy four patients whom short-term surgical procedure was planned in the Gynecology and Obstetrics Clinic were randomized into two groups for desflurane anesthesia (group D) and TIVA (group T). Voice recording was performed through larynx examination before anesthesia. Perioperative hemodynamic parameters, airway complications and postoperative airway complications were recorded. Laryngeal examination and voice recording were performed for the second time after 24 hours following the anesthesia procedure. Acoustic voice analysis of the patients was evaluated through the Praat program. The conditions including sore throat, dysphagia, and hoarseness were investigated after the anesthesia. Acoustic and aerodynamic properties of the voice, airway complications and pharyngolaryngeal complaints related to the use of SADs were compared in the patients.

RESULT

There was not any significant difference between the groups for demographic data. The SADs type and size have similar characteristics. No significant difference was detected between Group T and Group D for anesthesia duration (P = 0.964). Both anesthesia methods cause similar effects on pharyngolaryngeal functions and voice. No significant difference was found between Group T and Group D in parameters other than the shimmer value of acoustic analysis. A statistically significant increase was observed in the Shimmer variable of group D (P < 0.05). When group T and group D were compared, there was not any significant difference in terms of airway complications, sore throat, dysphagia, and hoarseness.

CONCLUSION

The TIVA and desflurane anesthesia presented similar clinical effects on voice and pharyngolaryngeal morbidity in the short-term gynecological operations through SADs. The increased shimmer value of acoustic voice analysis in Group D suggests that desflurane anesthesia may cause clinically insignificant deterioration on the voice. Further comprehensive studies are needed in order to demonstrate the effect of anesthetic agents on larynx functions in patients whom SADs is used.

Comparison of the Baska Mask® and Endotracheal Tube on Hemodynamic and Respiratory Parameters in Septoplasty Cases

Laryngeal mask (LM) types have been used as an airway device for an alternative to the standard endotracheal tube (ETT). One of the novel type of LM, the Baska Mask®, can be a safe alternative among the airway devices. The purpose of this study is to compare the effects of the new generation supraglottic airway device the Baska Mask® and the ETT on hemodynamic parameters (heart rate, mean arterial pressure), airway pressure and end tidal carbon dioxide (EtCO2) in patients undergoing general anesthesia. After the approval of the ethics committee, 70 patients who underwent septoplasty were included in the study. Written informed consent forms were taken from these patients. Demographic data of the patients were recorded. Hemodynamic data of patients were measured and recorded preoperative, during induction, at the time of intubation 1th, 3th and 5th minute and during extubation. Also, airway pressure and EtCO2 values of the patients were measured and recorded at the time of intubation, 1th, 3th and 5th minutes. Demographic data were similar in both groups. Mean arterial pressure, heart rate and airway pressure were lower in the group 2 (the Baska Mask® group) than in the group 1 (ETT group) and the difference was statistically significant (p&lt;0.05). EtCO2 values were similar in both groups. No patients had tube leakage. In terms of hemodynamic and respiratory parameters the Baska Mask® is more advantageous than the ETT in short-term surgeries.

Supraglottic Airway Devices and Effect on Voice-Comparison of LMA Proseal and i-gel: Double-Blind Randomized Clinical Trial

OBJECTIVES

Laryngeal mask airway (LMA) is an important alternative to endotracheal intubation for all professional voice users undergoing surgery. However, dysphonia is a known complication of LMA Proseal (PLMA) use. The i-gel airway (IGA) provides adequate airway seal without the need for an inflatable cuff. Hence, it helps to minimize the risk of tissue compression. This study compares effect of PLMA and IGA on voice at 24th hour after anesthesia.

DESIGN

This is a double-blind randomized clinical trial.

METHODS

Ninety anesthesiologists class 1 adults scheduled for surgeries lasting up to 60-120 minutes were included in the study. Participants were randomly allocated to group PLMA (n = 43) and group IGA (n = 43). Cuff pressure was monitored and maintained at just seal pressure in group PLMA. Voice was evaluated using perceptive and acoustic analysis (jitter, shimmer, and harmonics-to-noise ratio [HNR]) preoperatively and at 24th hour after anesthesia. Voice of patients with pharyngolaryngeal complaints was categorized into rough, breathy, asthenic, strain, or normal pattern.

RESULTS

Acoustic parameters jitter, shimmer, and HNR deteriorated significantly in both group PLMA and IGA albeit the change being comparable. Incidence of pharyngolaryngeal complaints was similar in both the groups. A total of 10% patients in group PLMA and 12.5% in group IGA developed breathy voice significant deterioration in all acoustic variables at 24th postoperative hour, but differences were not significant between group PLMA and group IGA.

CONCLUSIONS

PLMA and IGA both produce comparable and significant deterioration in acoustic variables at 24th hour after short duration general anesthesia.

Unilateral Hypoglossal Nerve Palsy Following the Use of the Laryngeal Mask Airway

Hypoglossal nerve injury is a rare complication of anesthetic airway management. We report a case of unilateral hypoglossal nerve injury following the use of the laryngeal mask airway (LMA). A 48-year-old man with no past medical history sustained a proximal humerus fracture. His pre-operative examination was normal except for a humerus fracture. Anesthesia was induced and a size-3 LMA was inserted successfully on first attempt without difficulty. The cuff was inflated with the recommended 20 ml of air until there was no leak and maintained at a pressure of 10-15 cm H20. The surgery was uneventful and the duration of anesthesia was two hours. Peri-operatively the patient was hemodynamically stable without episodes of hypotension. The recovery staff noted approximately three hours after the surgery that his tongue was deviated to the left. The patient complained of difficulty swallowing and slurred speech. He had normal sensation of his tongue, taste was unchanged, and the gag reflex was intact. No other cranial nerves were involved and no other neurological deficiency was found. The following day, there was significantly less dysarthria and slight improvement in tongue movement. Conservative management included speech therapy and regular assessment. He continued to improve and complete recovery took place within two weeks.

Laryngeal mask airways have a lower risk of airway complications compared with endotracheal intubation: a systematic review

PURPOSE

The purpose of the present study was to determine whether, in patients undergoing general anesthesia, those provided with a laryngeal mask airway (LMA) have a lower risk of airway-related complications than those undergoing endotracheal intubation.

MATERIALS AND METHODS

A systematic review of randomized prospective controlled trials was done to compare the risk of airway complications with an LMA versus an endotracheal tube (ETT) in patients receiving general anesthesia. Two independent reviewers identified 29 randomized prospective controlled trials that met the predetermined inclusion and exclusion criteria. The data for each individual outcome measure were combined to analyze the relative risk ratios (RRs). The Cochrane RevMan software was used for statistical analysis.

RESULTS

When an ETT was used to protect the airway, a statistically significant greater incidence of hoarse voice (RR 2.59, 95% confidence interval [CI] 1.55 to 4.34), a greater incidence of laryngospasm during emergence (RR 3.16, 95% CI 1.38 to 7.21), a greater incidence of coughing (RR 7.12, 95% CI 4.28 to 11.84), and a greater incidence of sore throat (RR 1.67, 95% CI 1.33 to 2.11) was found compared with when an LMA was used to protect the airway. The differences in the risk of regurgitation (RR 0.84, 95% CI 0.27 to 2.59), vomiting (RR 1.56, 95% CI 0.74 to 3.26), nausea (RR 1.59, 95% CI 0.91 to 2.78), and the success of insertion on the first attempt (RR 1.08, 95% CI 0.99 to 1.18) were not statistically significant between the 2 groups.

CONCLUSIONS

For the patients receiving general anesthesia, the use of the LMA resulted in a statistically and clinically significant lower incidence of laryngospasm during emergence, postoperative hoarse voice, and coughing than when using an ETT. The risk of aspiration could not be determined because only 1 study reported a single case of aspiration, which was in the group using the ETT.

Immediate post-operative vocal changes in patients using laryngeal mask airway versus endotracheal tube

Objective and hypothesis:

(1) To examine the vocal symptoms and acoustic changes perceived in the short period immediately after laryngeal mask airway, and (2) to compare these findings in patients using laryngeal mask airway and endotracheal tube.

Materials and methods:

A total of 27 patients were enrolled. They were evaluated pre-operatively and then at 2 and 24 hours post-operatively. Patients were divided into two subgroups, laryngeal mask airway and endotracheal tube. Patients were asked about the presence or absence of the following: hoarseness, vocal fatigue, loss of voice, throat-clearing sensation, globus pharyngeus and throat pain. Patients then underwent acoustic analysis of their voice, measuring the average fundamental frequency, relative average perturbation, shimmer, noise to harmony ratio, voice turbulence index, habitual pitch and maximum phonation time.

Results:

In the laryngeal mask airway group, there was an increase in the incidence of all vocal symptoms two hours post-operatively, except for globus pharyngeus. The increase was statistically significant for vocal fatigue, loss of voice and throat pain. All the symptoms had reverted back to a normal baseline level by 24 hours. There was a decrease in the maximum phonation time and habitual pitch, with an increase in all the perturbation parameters, two hours post-operatively. At 24 hours, an increase was still present for shimmer, noise to harmony ratio and voice turbulence index. The maximum phonation time and habitual pitch reverted back to normal values.

In the endotracheal tube group, there was a significant increase two hours post-operatively in the incidence of hoarseness, loss of voice and throat pain. At 24 hours, all the symptoms reverted to baseline, except for vocal fatigue and throat pain. Two hours post-operatively, there was a significant decrease in maximum phonation time and an increase in all other parameters (however, the latter was significant only for relative average perturbation and noise to harmony ratio). At 24 hours, there was a significant increase in the maximum phonation time and a persistent (but statistically insignificant) increase in the average fundamental frequency, habitual pitch, noise to harmony ratio and voice turbulence index.

At two hours, there was more loss of voice and vocal fatigue in the laryngeal mask airway group, compared with the endotracheal tube group. At 24 hours, these symptoms were comparable in both groups. Comparing changes in acoustic parameters to baseline values in both groups, there were no statistically significant changes.

Conclusion:

Shortly after reversal of anaesthesia, laryngeal symptoms following laryngeal mask airway are no less significant than those experienced following endotracheal tube anaesthesia. Both methods can be regarded as nontraumatic, in view of the lack of significant vocal symptoms and acoustic changes 24 hours after anaesthesia.

Effects on vocal function and incidence of laryngeal disorder when using a laryngeal mask airway in comparison with an endotracheal tube

A study of 56 patients was undertaken to determine whether there is a difference in the effect of the laryngeal mask airway and the endotracheal tube on the vocal tract after short-duration anaesthesia. All the patients were interviewed pre- and post-operatively. In 43 patients, it was possible to assess the larynx using videoendoscopy and videostrobolaryngoscopy both pre- and post-operatively. Selected acoustic characteristics were investigated in 51 patients pre- and 18-24 h post-operatively. Thirty-four patients that did not have anaesthesia were used as an age-matched control. The interview showed, that patients in the LMA group complained less frequently of having post-operative laryngeal discomfort. The videostrobolaryngoscopy demonstrated minor lesions of the vocal tract in six patients in the ETT group and in one patient in the LMA group. Of the 12 voice variables evaluated, there was no significant difference in any parameter between the two groups. Both groups had a higher fundamental frequency post-operatively.

Recurrent laryngeal nerve injury caused by a laryngeal mask airway

Although there have been few reports of serious complications with the laryngeal mask airway, we record a case of permanent unilateral vocal cord paralysis following the use of a laryngeal mask airway and review the literature describing injuries, not only to the recurrent laryngeal nerves but also to the hypoglossal and lingual nerves.

Laryngo-pharyngeal complaints after use of the laryngeal mask airway

PURPOSE

To compare the incidence of dysphagia, dysphonia and sore throat following anesthesia, using the laryngeal mask airway (LMA), among patients receiving intermittent positive-pressure ventilation (IPPV) and those breathing spontaneously (SV) and with two different concentrations of nitrous oxide (N2O) in oxygen.

METHODS

In a prospective trial, 120 patients (ASA I-III, 16-70 yr, > 60 kg) undergoing minor peripheral surgery were randomised into four groups with respect to type of ventilation and N2O concentration (50% or 66%) received. Cuff pressure measurements were monitored continuously. Twenty-four hours after surgery, patients were questioned for sore throat, dysphagia and dysphonia.

RESULTS

At 30 min post-LMA insertion, increases in cuff pressure were 35.2+/-17.1 mmHg (22.8%) vs 50.1+/-16.3 mmHg (32.7%) in patients breathing 50 and 66% N2O, respectively (P < 0.01). There were no differences in cuff pressure increment between patients in the SV and IPPV groups. Cuff pressure values at the end of surgery depended on the duration of surgery and on the concentrations of N2O. The overall incidence of postoperative discomfort at 24 hr was dysphagia 11%, dysphonia 11% and sore throat 28.8%. Only two patients reported sore throat as more than mild. There was no relationship between cuff pressure and laryngo-pharyngeal complaints. The incidence of dysphonia in the groups receiving IPPV was higher than that in the groups with spontaneous ventilation (17.2 vs 5%, P < 0.05).

CONCLUSION

Post-operative discomfort is related to the type of ventilation but not to variation in LMA cuff pressure.

The vocal athlete and endotracheal intubation: a management protocol

Endotracheal intubation is associated with significant laryngeal sequelae that range in severity from mild hoarseness to life-threatening tracheal stenosis. Although the most severe trauma appears to be related to prolonged intubation, even short-term intubation (< 1 day) can adversely affect laryngeal and vocal function. Concern is warranted for all intubated patients, but particularly for the vocal athlete whose livelihood and identity depend on optimal vocal function. It is proposed that the vocal athlete faced with endotracheal intubation risk warrants careful multidisciplinary management. A number of intubation risk factors have been identified in the literature; however, clinical management of vocal athletes who undergo intubation has not been addressed. In medical settings where adverse intubation outcomes can lead to litigation, this clinical management protocol is expected to improve the probability of favorable voice outcome following endotracheal intubation.

Use of the laryngeal mask airway in oral and maxillofacial surgery

PURPOSE

General anesthesia for the nonintubated oral and maxillofacial surgical patient presents unique anesthetic conditions. The primary concern is the maintenance of an unobstructed airway and protection against aspiration, while minimizing both interference and interruption of the surgical procedure. The laryngeal mask airway is an alternative to the nasal hood for such airway management. The purpose of this article is to inform the oral and maxillofacial surgeon of the clinical relevant information pertaining to the use of the laryngeal mask airway in oral and maxillofacial surgery. Experience with clinical use is discussed.

The laryngeal mask airway: a new technique for fiberoptic guided vocal cord biopsy

STUDY OBJECTIVE

To describe a new technique for vocal cord biopsy involving placement of a laryngeal mask airway (LMA) during general anesthesia and fiberoptic guided biopsy. To report our early experience with this technique.

DESIGN

Descriptive study.

SETTING

Teaching hospital.

PATIENTS

10 patients undergoing vocal cord biopsy for minor laryngeal pathology and with no evidence of infraglottic airway obstruction.

INTERVENTIONS

Patients were premedicated 1 hour preoperatively with pethidine 1 mg/kg and atropine 0.01 mg/kg. Following preoxygenation, anesthesia was induced with propofol 2.5 mg/kg and fentanyl 1 mg/kg. Once airway control was established with a facemask, vecuronium 0.1 mg was given and anesthesia established with oxygen (O2) and nitrous oxide mixture and isoflurane 1% to 2%. Gentle direct laryngoscopy was then performed to inspect the pharyngeal structures and the LMA was then inserted in the standard manner by highly experienced LMA users. A fiberoptic scope was passed via a self-sealing mount down the shaft of the LMA to the level of the vocal cords. The vocal cords were then sprayed with local anesthetic and the biopsy taken.

MEASUREMENTS AND MAIN RESULTS

The age and weight range were 29 to 57 years and 65 to 85 kg, respectively. All patients were smokers or recent ex-smokers. LMA insertion was readily achieved in all patients, and an excellent view of the vocal cords was obtained. There were no problems with ventilation or obtaining tissue samples, and O2 saturation remained greater than 95% throughout the perioperative period. Tissue samples were adequate in all patients. Hypertension and other adverse cardiac events did not occur during the procedure, which lasted 10 to 20 minutes. There were no problems during emergence from anesthesia, and all patients were discharged home on the same day.

CONCLUSIONS

The technique has potential advantages over suspension microlaryngoscopy in that it is relatively noninvasive, it allows good airway control with adequate views of the vocal cords, and it facilitates a smooth recovery.

Vocal fold palsy after use of the laryngeal mask airway

We report two cases of left vocal fold palsy following use of the laryngeal mask airway. In both cases anaesthesia was uneventful with a duration of about 60 minutes. It is proposed that high intra-cuff pressures induced during anaesthesia resulted in distension of the hypopharynx and subsequent neuropraxia of the motor branches of the recurrent laryngeal nerve and the external branch of the superior laryngeal nerve.

The laryngeal mask airway--anatomical and physiological implications

The laryngeal mask airway (LMA) is a relatively new general purpose airway which fills a niche between the face mask and tracheal tube, both in terms of anatomical location and degree of invasiveness. It sits in the hypopharynx at the interface between the gastrointestinal and respiratory tracts, where it forms a circumferential low pressure seal around the glottis. This has advantages in terms of gas flow through the upper airway and allows direct access to the glottis without loss of airway control. LMA insertion can be considered in the context of swallowing and combines the ability to insert blindly whilst avoiding collision with highly innervated anterior pharyngeal structures. This review deals briefly with the concepts behind LMA design and insertion, and focuses on the anatomical and physiological implications of the LMA with respect to the swallowing reflex, the oesophagus, the pharyngeal mucosa, pulmonary defences, pulmonary mechanics and the cardiovascular system. The possible role of the LMA as a monitor of anaesthetic depth and areas of future research are also discussed.

The advantages of the LMA over the tracheal tube or facemask: a meta-analysis

A meta-analysis was performed on randomised prospective trials comparing the laryngeal mask airway (LMA) with other forms of airway management to determine if the LMA offered any advantages over the tracheal tube (TT) or facemask (FM). Of the 858 LMA publications identified to December 1994, 52 met the criteria for the analysis. Thirty-two different issues were tested using Fisher's method for combining the P values. The LMA has 13 advantages over the TT and four over the FM. The LMA had two disadvantages over the TT and one over the FM. There were 12 issues where neither device had an advantage. Advantages over the TT included: increased speed and ease of placement by inexperienced personnel; increased speed of placement by anaesthetists; improved haemodynamic stability at induction and during emergence; minimal increase in intraocular pressure following insertion; reduced anaesthetic requirements for airway tolerance; lower frequency of coughing during emergence; improved oxygen saturation during emergence; and lower incidence of sore throat in adults. Advantages over the FM included: easier placement by inexperienced personnel; improved oxygen saturation; less hand fatigue; and improved operating conditions during minor paediatric otological surgery. Disadvantages over the TT were lower seal pressures and a higher frequency of gastric insufflation. The only disadvantage compared with the FM was that oesophageal reflux was more likely. The importance of these findings in terms of patient outcome could not be determined from the published data.

The laryngeal mask airway: its features, effects and role

The laryngeal mask airway was designed as a new concept in airway management and has been gaining a firm position in anaesthetic practice. Numerous articles and letters about the device have been published in the last decade, but few large controlled trials have been performed. Despite widespread use, the definitive role of the laryngeal mask has yet to be established. In some situations, such as after failed tracheal intubation or in anaesthesia for patients undergoing laparoscopic or oral surgery, its use is controversial. There are a number of unresolved issues, for example the effect of the laryngeal mask on regurgitation and whether or not cricoid pressure prevents placement of the mask. We review the techniques of insertion, details of misplacement, and complications associated with the use of the laryngeal mask. We discuss the features and physiological effects of the device, including the changes in intra-cuff pressure during anaesthesia and effects on blood pressure, heart rate and intra-ocular pressure. We then attempt to clarify the role of the laryngeal mask in airway management during anaesthesia, based on the current knowledge, by discussing the advantages and disadvantages as well as the indications and contraindications of its use. Lastly we describe the use of the laryngeal mask in circumstances other than airway maintenance during anaesthesia: fibreoptic bronchoscopy, tracheal intubation through the mask and its use in cardiopulmonary resuscitation.

Laryngeal mask airway cuff pressure and position during anaesthesia lasting one to two hours

The cuff of the laryngeal mask airway (LMA) is highly permeable to nitrous oxide (N2O), and cuff pressure increases during N2O/O2 anaesthesia. The extent of these changes and their effect on LMA position have previously only been investigated for short procedures. The current study was designed to investigate the effects of nitrous oxide-oxygen (N2O/O2) anaesthesia lasting one to two hours on cuff pressure, LMA positioning and pharyngeal morbidity. Twenty-four male patients underwent spontaneous ventilation anaesthesia with 66% N2O in oxygen and isoflurane. Following insertion and inflation of a #4 LMA with 30 ml air, mean (SD) cuff pressures immediately increased from 107 (9) to 145 (12) mmHg and then at a decreasing rate for 90 min to peak at 215 (12) mmHg. There was a correlation between N2O concentration and final cuff volume (P < 0.001). There was no displacement of the LMA cuff in any patient. Three of 19 patients had a mild sore throat. This study demonstrates that the increase in LMA cuff pressure is self limiting over a one-to-two-hour period and does not cause displacement of the LMA. There is no evidence that cuff pressure monitoring and pressure limitation is necessary during LMA anaesthesia.