Reducing the incidence of sore throat with the laryngeal mask airway

Evaluation of gender differences in postoperative sore throat and hoarseness following the use of Ambu AuraGain laryngeal mask: the randomised controlled LadyLAMA trial study protocol

INTRODUCTION

Postoperative sore throat (POST) is a comparatively minor but very common side effect of general anaesthesia with a supraglottic airway device. The patient considers these side effects a mirror of the quality of anaesthesia. The aims of this study are to evaluate gender-specific differences in the incidence of POST and to assess whether the effects of known risk factors vary between genders.

METHODS AND ANALYSIS

The LadyLAMA trial is a single-centre, patient-blinded, randomised controlled trial. Consecutive patients requiring ophthalmological surgery under general anaesthesia with a second generation Ambu AuraGain laryngeal mask are randomly allocated to either cuff pressure of 45 cmH2O or cuff pressure of 60 cmH2O. We estimate the difference in POST between the genders at 20% and we hypothesised that a reduction of cuff pressure would reduce POST by 10%. A total of 800 patients will be recruited, with each subgroup including 200 patients to achieve 80% power for detecting a difference at the 5% significance level. Primary endpoints are gender differences in the incidence of POST within 24 hours postoperatively, as well as comparison of cuff pressure 45 cmH2O to 60 cmH2O with respect to POST. The main secondary objective is the effect of cuff pressure on POST stratified by gender. Further secondary endpoints are gender-specific differences in POST and hoarseness in postanaesthesia care unit (PACU) at 48 and 72 hours (or until freedom of discomfort). The parameter cuff pressure serves as key-secondary endpoint.

ETHICS AND DISSEMINATION

The project is approved by the local ethics committee of the Medical Association of the Rhineland Palatine state (Nr. 2021-15835). The results of this study will be made available in the form of manuscripts for publication and presentations at national and international meetings.

TRIAL REGISTRATION NUMBER

NCT04915534.

A Randomized Crossover Comparison of Airway Sealing with the Laryngeal Mask Airway Ambu AuraFlex at Three Intracuff Pressures in Pediatric Laparoscopic Surgery

OBJECTIVE

An adequate intracuff pressure is important to ensure sufficient sealing function when using supraglottic airway devices to protect the airway from secretions and achieve adequate positive pressure ventilation. The aim of this study is to analyze a feasible and effective alternative Ambu AuraFlex intracuff pressure in child's laparoscopic surgery.

STUDY DESIGN

Seventy-two children were included in this study. After insertion of the laryngeal mask airway AuraFlex, oropharyngeal leak pressure (OLP) was measured at intracuff pressures of 10, 30, and 60-cmH₂O according to one of six sequences produced on the basis of 3 × 6 Williams crossover design. During the intraoperative period, AuraFlex was maintained using the last intracuff pressure of the allocated sequence. Oropharyngeal leak pressure, peak airway pressure, the fiberoptic view, mucosal change, and complications were assessed at three intracuff pressures.

RESULTS

The OLP at the intracuff pressure of 10 cmH₂O was significantly lower than that of 30 cmH₂O (2^# 18.1 ± 1.5 vs. 19.5 ± 1.4 cmH₂O, p = 0.001; 2.5^# 17.7 ± 1.2 vs. 20.2 ± 1.4, p = 0.001) and 60 cmH₂O (2^# 18.1 ± 1.5 vs. 20.0 ± 1.3 cmH₂O, p = 0.002; 2.5^# 17.7 ± 1.2 vs. 20.8 ± 1.1, p = 0.003). Compared with the peak airway pressure in pre-and postpneumoperitoneum, the OLP was significantly higher. Subgroup analysis showed no differences in mucosal change and complications.

CONCLUSION

Intracuff pressures of 30 may be sufficient for the Ambu AuraFlex in child's laparoscopic surgery, and there may be no added benefit of an intracuff pressure of 60 cmH₂O, as oropharyngeal leak pressures were similar.

Clinical Outcomes of a Modified Laryngeal Mask Airway (LMA® Gastro™ Airway) During Esophagogastroduodenoscopy in Children and Adolescents: A Randomized Study

Introduction

During esophagogastroduodenoscopy (EGD), general anesthesia (GA) may be provided using a laryngeal mask airway (LMA) with the endoscope inserted behind the cuff of the LMA into the esophagus. Passage of the endoscope may increase the intracuff of the LMA. We evaluated a newly designed LMA (LMA^® Gastro™ Airway) which has an internal channel exiting from its distal end to facilitate EGD. The current study compared the change of LMA cuff pressure between this new LMA and a standard clinical LMA (Ambu^® AuraOnce™) during EGD.

Methods

Patients less than 21 years of age and weighing more than 30 kg were randomized to receive airway management with one of the two LMAs during EGD. After anesthetic induction and successful LMA placement, the intracuff pressure of the LMAs was continuously monitored during the procedure. The primary outcome was the change of intracuff pressure of the LMAs.

Results

The study cohort included 200 patients (mean age 13.6 years and weight 56.6 kg) who were randomized to the LMA^® Gastro™ Airway (n=100) or the Ambu^® AuraOnce™ LMA (n=100). Average intracuff pressures during the study period (before and after endoscope insertion) were not different between the two LMAs. Ease of the procedure was slightly improved with the LMA^® Gastro™ Airway (p<0.001).

Discussion

The LMA^® Gastro™ Airway blunted, but did not prevent an increase in intracuff pressure during EGD when compared to the Ambu^® AuraOnce™ LMA. Throat soreness was generally low, and complications were infrequent in both groups. The ease of the procedure was slightly improved with the LMA^® Gastro™ Airway compared to the Ambu^® AuraOnce™ LMA.

Randomized Evaluation of the Single-use SoftSeal™ and the Re-useable LMA Classic™ Laryngeal Mask

A number of laryngeal masks are available, including both re-usable and single-use masks. Single-use laryngeal masks may decrease the risk of transmitting prion infections. We performed a single-blind randomized trial in 200 spontaneously breathing female patients under general anaesthesia with nitrous oxide, to compare a new single-use laryngeal mask, the SoftSeal™ (Portex Ltd, U.K.), with a re-usable laryngeal mask, the LMA Classic™ (Laryngeal Mask Company Ltd., Cyprus). The primary outcome was successful insertion at the first attempt. Size 4 single-use (n=99) or re-usable (n=100) laryngeal masks, inserted by experienced anaesthetists, were equivalent for successful placement at the first attempt (90% versus 91% respectively). The single-use mask was less easy to insert (47% difficult versus 9%, P<0.001). Clinical and anatomical tests of position and function were similar. The cuff pressure of the re-usable mask increased significantly compared with the single-use mask (median +10 cm versus –2 cm H 2 O, P<0.001). Forty per cent of patients allocated the single-use mask and 20% of those allocated the re-usable mask experienced sore throat at 24 hours postoperatively (P<0.05). An estimation of cost per patient use was greater for the re-usable mask.

We conclude that the SoftSeal™ single-use laryngeal mask and the LMA Classic™ re-usable laryngeal mask airway are of similar clinical utility in terms of successful insertion and airway maintenance. The re-usable laryngeal mask was easier to insert and associated with less postoperative sore throat, but costs were higher.

Optimal flexible laryngeal mask airway size in children weighing 10 to 20 kg

This prospective, randomised study was conducted to assess the effect of flexible laryngeal mask airway (FLMA) size on oropharyngeal leak pressure (OLP) in children at the recommended intracuff pressure. A total of 120 children undergoing elective ophthalmic surgery were randomly assigned to the size 2 FLMA group or size 2.5 FLMA group. The primary measurement was OLP at an intracuff pressure of 40 cmH₂O. Secondary outcomes included the incidence of OLP <10 cmH₂O, insufficient ventilation, gastric insufflation, insertion time, successful first-attempt insertion rate, fibreoptic view grade and pharyngolaryngeal adverse events. The median OLP was comparable for the size 2 and size 2.5 FLMA (18 cmH₂O versus 18 cmH₂O, P=0.38). However, the size 2 FLMA group had a higher incidence of OLP <10 cmH₂O and insufficient ventilation (13.3% versus 0, P=0.006). In subgroup analyses based on weight, the size 2.5 FLMA had a lower occurrence of OLP <10 cmH₂O and insufficient ventilation (27% versus 0, P=0.0046) in children 16-20 kg. We conclude that at a 40 cmH₂O intracuff pressure, the OLP with the size 2 and size 2.5 FLMA was similar in children weighing 10-15.9 kg. However, in children weighing 16-20 kg, size 2 devices had a higher incidence of low OLP and insufficient ventilation, so a 2.5 FLMA may be preferable in this subgroup.

Evaluation of the optimal cuff volume and cuff pressure of the revised laryngeal tube "LTS-D" in surgical patients

Background

Recent case reports have indicated significant cuff overinflation when using the standard filling volume based on the manufacturer’s recommendations in older models of laryngeal tubes. The aim of this study was to determine the minimum cuff pressure needed to perform standardized ventilation without leakage in the new, revised model of the laryngeal tube “LTS-D”.

Methods

After ethical approval, LTS-D was placed for ventilation in 60 anesthetized patients. The cuff was inflated to the recommended volume (#3: 60 ml, #4: 80 ml, and #5: 90 ml). After evaluation of the initial cuff pressure (CP), the CP was lowered in 10 cmH₂O steps until a minimal cuff pressure of 30 cmH₂O was achieved. The absence of an audible leak was required for a step-by-step reduction in the CP. Evacuated cuff volume, success rate, and airway injuries were documented. Data were expressed as medians (interquartile ranges [IQRs]). The comparison of CPs and cuff volumes was performed using the Mann-Whitney test.

Results

After initial inflation, the CP ranged from 105 cmH₂O [90–120; #5] to 120 cmH₂O [110–120; #3]. Lowering the CP to 60 cmH₂O resulted in a reduced cuff volume ranging from 47 ml [44–54; #3] to 77 ml [75–82; #5] compared to the initial inflation (p < 0.001). Leakage occurred more frequently when the CP was lowered to 40 cmH₂O compared to the initial inflation (44/54 [81%]; p < 0.01). Using a CP between 50 cmH₂O and 60 cmH₂O, a leakage rate of 3/54 (5%) was observed, compared to a rate of 11/54 (21%) when using a CP lower than 50 cmH₂O. The overall success rate was 90%, and airway injury occurred in 7% of patients (4/60).

Conclusion

We found significant overinflation of the revised LTS-D using the recommended volume for initial cuff inflation. A CP of 60 cmH₂O was found to be sufficient for ventilation in the majority of patients evaluated. Checking and adjusting the CP in laryngeal tubes is mandatory to avoid overinflation.

Trial registration

ClinicalTrials.gov NCT02300337. Registered: 20 November 2014.

Electronic supplementary material

The online version of this article (doi:10.1186/s12871-017-0308-4) contains supplementary material, which is available to authorized users.

The effect of esophagogastroduodenoscopy probe insertion on the intracuff pressure of airway devices in children during general anesthesia

Given the size of the esophagogastroduodenoscopy (EGD) probe and the compressibility of the pediatric airway, the EGD probe may increase the intracuff pressure (IP) of an airway device. The current study evaluated IP changes during EGD examination under general anesthesia in pediatric patients. Following the induction of anesthesia, a laryngeal mask airway (LMA) or endotracheal tube (ETT) was placed without neuromuscular blockade. The IP was measured at baseline, during EGD probe insertion, while the EGD probe was in place, and after probe removal. The study cohort included 101 patients (mean age 11.3 years). The airway was secured with an LMA and an ETT in 88 and 13 patients, respectively. The IP increased from 27 ± 15 cmH₂O at baseline to 34 ± 17 cmH₂O during probe insertion (p < 0.001), remained at 33 ± 16 cmH₂O while the probe was in place, and decreased to 26 ± 14 cmH₂O after probe removal. The IP of the LMA or ETT increased during EGD probe insertion and remained elevated while the probe was in place. High IP may compromise mucosal perfusion resulting in a sore throat when using an LMA or the potential for airway damage if an ETT is used. Removal of air from the cuff and titration of the IP should be considered after EGD insertion.

Comparison of effects of ProSeal LMA™ laryngeal mask airway cuff inflation with air, oxygen, air:oxygen mixture and oxygen:nitrous oxide mixture in adults: A randomised, double-blind study

Background and Aims:

Laryngeal mask airway (LMA) cuff pressure increases when the air is used for the cuff inflation during oxygen: nitrous oxide (O₂:N₂O) anaesthesia, which may lead to various problems. We compared the effects of different gases for ProSeal LMA™ (PLMA) cuff inflation in adult patients for various parameters.

Methods:

A total of 120 patients were randomly allocated to four groups, according to composition of gases used to inflate the PLMA cuff to achieve 40 cmH₂ O cuff pressure, air (Group A), 50% O₂ :air (Group OA), 50% O₂:N₂O (Group ON) and 100% O₂ (Group O). Cuff pressure, cuff volume and ventilator parameters were monitored intraoperatively. Pharyngolaryngeal parameters were assessed at 1, 2 and 24 h postoperatively. Statistical analysis was performed using ANOVA, Fisher's exact test and step-wise logistic regression.

Results:

Cuff pressure significantly increased at 10, 15 and 30 min in Group A, OA and O from initial pressure. Cuff pressure decreased at 5 min in Group ON (36.6 ± 3.5 cmH₂ O) (P = 0.42). PLMA cuff volume increased in Group A, OA, O, but decreased in Group ON (6.16 ± 2.8 ml [P < 0.001], 4.7 ± 3.8 ml [P < 0.001], 1.4 ± 3.19 ml [P = 0.023] and − 1.7 ± 4.9 ml [P = 0.064], respectively), from basal levels. Ventilatory parameters were comparable in all four groups. There was no significant association between sore throat and cuff pressure, with odds ratio 1.002.

Conclusion:

Cuff inflation with 50% O₂:N₂O mixture provided more stable cuff pressure in comparison to air, O₂ :air, 100% O₂ during O₂:N₂O anaesthesia. Ventilatory parameters did not change with variation in PLMA cuff pressure. Post-operative sore throat had no correlation with cuff pressure.

Digital palpation of the pilot balloon vs. continuous manometry for controlling the intracuff pressure in laryngeal mask airways

This study compared two methods of controlling the intracuff pressure in laryngeal mask airways. One hundred and eighty patients were randomly assigned into two groups. In the first group (n = 90), after training, the intracuff pressure was controlled using digital palpation of the pilot balloon. In the second group (n = 90), continuous manometry was used to control the intracuff pressure. An upper pressure limit of 60 cmH2 O was set. The median (IQR [range]) intracuff pressure in the palpation group was 130 (125-130 [120-130]) cmH2 O compared with 29 (20-39 [5-60]) cmH2 O in the manometry group (p < 0.001). In the palpation group, 37% of patients experienced pharyngolaryngeal complications vs. 12% in the manometry group (p < 0.001). We conclude that the digital palpation technique is not a suitable alternative to manometry in controlling the intracuff pressure in laryngeal mask airways.

Application of Minimum Effective Cuff Inflating Volume for Laryngeal Mask Airway and its Impact on Postoperative Pharyngeal Complications

BACKGROUND

High intracuff pressure can cause severe pharyngeal complications including sore throat or hoarseness after laryngeal mask airway (LMA) removal postoperatively. Though the application of minimum effective cuff inflating volume is suggested to maintain airway sealing and adequacy of ventilation for patients receiving general anesthesia with LMA at lower level of the intracuff pressure, it is currently not a standard care in most of the anesthetic departments. In this study, the minimum effective cuff inflating volume was determined for classic LMA Well Lead™ (Well Lead Medical Co., Ltd., China) and its impact on postoperative pharyngeal complications was also explored.

METHODS

Patients with American Society of Anesthesiologists physical status (I-III) undergoing the short-duration urological surgery were recruited in this trial. First, the minimum effective cuff inflating volume was determined for size 4 or 5 LMA Well Lead in the study 1. Immediately following placement and confirmation of ideal LMA position, the cuff was inflated with 5, 7, 10 ml of air and up to 30 ml at 5 ml increment. The intracuff pressure, oropharyngeal leak pressure (OLP), and inspiratory peak airway pressure under positive pressure ventilation at the corresponding cuff volume as indicated above were recorded. Second, the enrolled patients were randomly allocated into minimum effective cuff inflating volume group (MC) and routine care (RC) group in the study 2. The minimum effective cuff inflating volume was applied and maintained in MC group, whereas the cuff volume was inflated with half of the maximum cuff inflating volume recommended by manufacturer in RC group throughout the surgical procedure and stay in postanesthesia care unit prior to LMA removal. The incidence of pharyngeal complications at 0, 2, 24, and 48 h after removal of LMA and other intra-operative adverse events were also documented.

RESULTS

The intracuff pressure varied with the cuff inflating volume in a positive linear correlation manner (Y = 11.68X - 42.1, r(2) = 0.9191) under the range of 5-30 ml for size 4 LMA. In similar with size 4 LMA, the data were also showed the linear relationship between the intracuff pressure and the cuff inflating volume (Y = 7.39X - 10.9, r(2) = 0.8855) for size 5 LMA. The minimal effective cuff inflating volume for size 4 or 5 LMA was 7-9 ml in combination of considering OLP needed to maintain airway sealing during intermittently positive pressure ventilation. The intracuff pressure in MC group was lower compared with RC group (63.0 ± 3.7 vs. 126.4 ± 24.0 cmH2O for size 4 LMA; 55.6 ± 2.4 vs. 138.5± 26.8 cmH2O for size 5 LMA; P < 0.0001). The incidence of pharyngeal adverse events was lower in MC group versus the RC group at 2, 24 h after LMA removal.

CONCLUSIONS

The relationship between the cuff inflating volume and the intracuff pressure for size 4 or 5 LMA Well Lead(TM) is in a linear correlation manner at the range of 5-30 ml. The minimal cuff inflating volume is adequate for satisfactory airway sealing and consequently associated with lower incidence of postoperative pharyngeal complications for LMA Well Lead.™.

[Continuous cuff pressure measurement during laryngeal mask anesthesia : An obligatory measure to avoid postoperative complications]

BACKGROUND

Inflation of laryngeal masks is often performed only with regard to the clinical impression and without any objective measurement of cuff pressure. As a result the use of laryngeal masks frequently leads to postoperative complications, such as sore throat, dysphonia, dysphagia and nerve palsy. In this study the influence of continuous measurement of cuff pressure on the incidence of postoperative sore throat was investigated in patients who underwent laryngeal mask anesthesia.

PATIENTS/MATERIAL AND METHODS

In the context of a retrospective audit all patients who underwent laryngeal mask anesthesia were asked to complete a questionnaire on anesthesia. The primary endpoint of the study was the postoperative occurrence of a sore throat. For analysis the patients were divided into two groups. In the first group the cuff pressure was controlled only by clinical means and in the second group the cuff pressure was controlled using continuous manometry. The study covered a 10-month period of observation for each group.

RESULTS

During the observation period laryngeal mask anesthesia was performed in 4169 patients. Of these 917 patients (manometry group n = 433 and control group n = 484) voluntarily completed the questionnaire. In the group without cuff pressure measurement 36 % of patients complained of sore throat postoperatively but only 12 % of the patients in the group with cuff pressure measurement (p < 0.001). Postoperative nausea and vomiting occurred in 16 % of the patients and 13 % complained of severe pain in the area of the operation. No differences between the two groups were found. While 97 % of patients in the group with continuous measurement of cuff pressure were satisfied with the anesthesia, this applied to only 79 % of patients in the control group (p = 0.006).

CONCLUSION

In terms of the results of this study and with respect to data from the literature, measurement of cuff pressure should be compulsory during laryngeal mask anesthesia.

Multicentre validation of manufacturers' weight-based recommendations for laryngeal mask airway size choice in anaesthetic practice: A retrospective analysis of 20,893 cases

BACKGROUND

Manufacturers' weight-based recommendations for laryngeal mask airway (LMA) sizes are not scientifically founded and have never been validated clinically.

OBJECTIVE

The validation of manufacturers' weight-based recommendations in clinical practice and whether other patient variables such as sex and age may influence LMA size choice.

DESIGN

A retrospective study.

SETTING

Four Israeli hospitals (two tertiary and two secondary hospitals).

METHODS

Data on LMA use were retrieved from the Anaesthesia Information Management System (AIMS). Multinomial logistic regression analysis including weight, sex and age amongst adults, adolescents and children was used to identify predictors of LMA size used (development data set). Concordance between the size of LMA used and that predicted according to the model and the manufacturers' recommendations was assessed (validation data set).

RESULTS

LMA insertions were analysed in 13,743 (65.8%) adults, 1807 (8.6%) adolescents and 5343 (25.6%) children. Suitability of manufacturers' recommendations was higher in children [4075/5343 (76.3%)] than adults [5200/13743 (37.8%)] or adolescents [885/1807 (49.0%); P < 0.001 for children vs. adults or adolescents]. Sex influenced LMA size in adults and adolescents, but not in children. Age had no influence. Amongst adults and adolescents, LMA size was better predicted by the regression model than by manufacturers' recommendations [adults: anaesthetists/model 61.7%, 95% confidence interval (95% CI) 60.1 to 63.2, anaesthetists/manufacturer 38.4%, 95% CI 36.0 to 39.0, P < 0.001; adolescents: anaesthetists/model 68.1%, 95% CI 64.1 to 72.0, anaesthetists/manufacturer 46.9%, 95% CI 42.7 to 51.1, P < 0.001]. In children, the regression model and manufacturers' weight-based recommendations performed equally (anaesthetists/model 78.0%, 95% CI 75.9 to 80.0, anaesthetists/manufacturer 75.7%, 95% CI 73.6 to 7.8, P = 0.126).

CONCLUSION

Manufacturers' weight-based recommendations for LMA size reflect clinical practice in children, but not in adults and adolescents. In these age groups, choice of LMA size is influenced by sex and weight, although with wider ranges than those recommended by manufacturers.

Comparisons of clinical performance of Guardian laryngeal mask with laryngeal mask airway ProSeal

Background

The Guardian Laryngeal Mask Airway (G-LMA) is a new silicone-based single-use extraglottic device with the drainage port and a cuff pilot valve with pressure indicator. The aim of this study is to compare the clinical performance of this laryngeal mask airway with ProSeal laryngeal mask airway (P-LMA).

Methods

In this prospective randomized study, we included adult patients with ASA grading I and II scheduled for elective surgery requiring supine position under total intravenous anesthesia. The patients were randomly allocated to two groups, 40 in each. G-LMA and P-LMA were used in groups G and P respectively. The cuff of each device was air inflated to 60 cmH₂O. The primary outcome was to compare the airway sealing pressure and the secondary outcome was to compare the efficacy and safety of these two devices with respect to insertion success, insertion time, ease of insertion, volume of air for cuff inflation to 60 cmH₂O, intracuff pressure measurement, gastric tube insertion attempt, gastric tube insertion time, Fiberoptic laryngeal view, and postoperative pharyngolaryngeal morbidity.

Results

The airway sealing pressure at 60cmH₂O cuff pressure was significantly greater in G-LMA than P-LMA (p = 0.04).The first successful attempt of both groups were comparable (p = 1.000). Insertion time was significantly shorter in G-LMA than P-LMA (p < 0.0001). The first successful attempt for the gastric tube insertion in both groups was comparable (p = 0.431). Gastric tube insertion time was less in G-LMA than in P-LMA (p < 0.0001). The volume of air for cuff inflation to 60 cmH₂O was more in G-LMA than in P-LMA (<0.0001). The intracuff pressure measurement at 30, 60, 90 and 120 minutes were comparable (p = 0.823, 0.182, 0.870, 0.658).We did not find differences in ease of insertion (p = 0.60); Fiber-optic positions of airway devices were comparable (p = 0.83). In addition, blood staining (p = 1.00), sore throat and dysphagia at 1, 2 and 24 hour (p = 1.00) were comparable in both groups.

Conclusion

The Guardian laryngeal mask airway was associated with high airway sealing pressure with a quicker insertion of the device as well as gastric tube.

Trial registration

Clinical Trial.gov Identifier: NCT02063516. Date: June 2013

Electronic supplementary material

The online version of this article (doi:10.1186/s12871-015-0039-3) contains supplementary material, which is available to authorized users.

Gender differences in sore throat and hoarseness following endotracheal tube or laryngeal mask airway: a prospective study

Background

Postoperative sore throat and hoarseness are common minor complications following airway manipulation. This study was primarily done to determine gender differences in the incidence of these symptoms and the location of POST after laryngeal mask airway (LMA) and endotracheal tube (ETT).

Methods

A total of 112 men and 185 women were included during a four month period. All patients were evaluated postoperatively and after 24 hours about the occurrence of sore throat, its location and hoarseness. If the patients had any symptom, they were followed-up at 48, 72 and 96 hours until the symptoms resolved.

Results

There was no significant gender difference in postoperative sore throat (POST) and postoperative hoarseness (PH) when analyzing both airway devices together. The incidence of sore throat and hoarseness were higher postoperatively after an ETT than an LMA (32% vs. 19%, p = 0.012) and 57% vs. 33% (p < 0.001) respectively. Significantly more women than men had POST after an LMA (26% vs. 6%, p = 0.004). No significant gender difference was found in either POST or PH after an ETT or in the incidence of PH after an LMA. More patients located their pain below the larynx after an ETT vs. an LMA (24% vs. 4%). Pain above the larynx was more common after an LMA than an ETT (52% vs. 37%).

Conclusions

In a clinical setting where women are intubated with a smaller size ETT than men, there were no significant differences in POST or PH between genders. Additionally, more women than men have POST when an LMA is used. Awareness of POST and PH may help streamline patients in whom the best airway device could be used during anesthesia and surgery.

Postoperative pharyngolaryngeal adverse events with laryngeal mask airway (LMA Supreme) in laparoscopic surgical procedures with cuff pressure limiting 25 cmH₂O: prospective, blind, and randomised study

To reduce the incidence of postoperative pharyngolaryngeal adverse events, laryngeal mask airway (LMA) manufacturers recommend maximum cuff pressures not exceeding 60 cmH₂O. We performed a prospective randomised study, comparing efficacy and adverse events among patients undergoing laparoscopic surgical procedures who were allocated randomly into low (limiting 25 cmH₂O, L group) and high (at 60 cmH₂O, H group) LMA cuff pressure groups with LMA Supreme. Postoperative pharyngolaryngeal adverse events were evaluated at discharge from postanaesthetic care unit (PACU) (postoperative day 1, POD 1) and 24 hours after discharge from PACU (postoperative day 2, POD 2). All patients were well tolerated with LMA without ventilation failure. Before pneumoperitoneum, cuff volume and pressure and oropharyngeal leak pressure (OLP) showed significant differences. Postoperative sore throat at POD 2 (3 versus 12 patients) and postoperative dysphagia at POD 1 and POD 2 (0 versus 4 patients at POD 1; 0 versus 4 patients at POD 2) were significantly lower in L group, compared with H group. In conclusion, LMA with cuff pressure limiting 25 cmH₂O allowed both efficacy of airway management and lower incidence of postoperative adverse events in laparoscopic surgical procedures. This clinical trial is registered with KCT0000334.

New supraglottic airway with built-in pressure indicator decreases postoperative pharyngolaryngeal symptoms: a randomized controlled trial

PURPOSE

Excessive supraglottic airway cuff pressure increases postoperative pharyngolaryngeal symptoms such as sore throat, dysphonia, and dysphagia. A new supraglottic airway, AES Ultra CPV™ (CPV), has a built-in intracuff pressure indicator. We hypothesized that using the CPV would reduce postoperative symptoms when compared with the LMA Classic™ (LMA) without intracuff pressure guidance.

METHODS

Ambulatory patients undergoing general anesthesia were randomized to either CPV or LMA. A size 3/4/5 was inserted according to manufacturer guidelines. Nitrous oxide was not used. In the LMA Group, the cuff was inflated according to manufacturer's guidelines. In the CPV Group, a CPV was inserted and the cuff inflated until the indicator was in the green zone (30-44 mmHg). Intracuff pressures were measured at five minutes and 20 min post-insertion in both groups. The primary outcome was the incidence of pharyngolaryngeal symptoms, defined as sore throat, dysphonia, and/or dysphagia at one, two, and/or 24 hr postoperatively. Continuous data were compared using Student's t test and categorical data were analyzed using Chi square analysis.

RESULTS

The study included 170 patients, 85 per group. The mean (SD) intracuff pressure in the CPV group was significantly lower [44 (4) mmHg] than in the LMA Group [87 (37) mmHg]; P < 0.001. The incidence of pharyngolaryngeal symptoms was significantly lower in the CPV Group than in the LMA Group (26% vs 49%; P = 0.002). The absolute risk reduction was 24%, and the number-needed-to-treat was 4.3.

CONCLUSION

The incidence of postoperative pharyngolaryngeal symptoms in the CPV Group with a cuff pressure-guided strategy was significantly lower than in the LMA Group with standard practice. (

CLINICAL TRIAL REGISTRATION NUMBER

NCT01800344).

Clinical evaluation of a novel LMA with a color-coded pressure gauge

BACKGROUND

Unintended hyperinflation of the cuff of a laryngeal mask airway (LMA) may be associated with increased airway morbidity and postoperative pain. While the manufacturers recommend a cuff pressure of ≤ 60 cmH(2)O, in usual clinical practice, there is no method used to determine the intracuff pressure. The purpose of this prospective study was to evaluate the accuracy of a newly designed LMA with a built in pressure gauge intended to alert the clinician to elevated intracuff pressures. The pressure gauge has a color code system intended to reflect the intracuff pressure with green being 40-60 cmH(2)O.

METHODS

There was no change dictated in clinical practice for these patients. Per our usual practice, the LMA was removed from the package and inserted with the cuff partially inflated. Additional air was added to the cuff using a syringe as needed to ensure a seal during positive pressure ventilation to a peak inflating pressure (peak ventilating pressure) of 20-25 cmH(2)O. The clinicians placing the LMA did not use the pressure gauge for clinical feedback during cuff inflation. Immediately after LMA placement, the pressure in the cuff of the LMA was measured using a hand held manometer by an independent reviewer not part of the patient's anesthetic management. The color indicated on the pressure gauge (yellow, green or red) was recorded prior to pressure sampling. Additional data collected included the patient's demographic data (age, weight, and gender), the size of the LMA, and whether air was added to the cuff.

RESULTS

The study cohort included 100 children, ranging in age from 3 months to 19 years and in weight from 5.4 to 80.1 kg. One patient was excluded due to malfunction of the pressure gauge and pilot balloon of the LMA. The intracuff pressure as measured by manometer correlated appropriately with the color coding of the pressure gauge in 94 of the 99 (95%) of the LMA's tested.

CONCLUSIONS

Given the potential association of excessive intracuff pressures with postoperative sore throat and the inability to ensure acceptable intracuff pressures using clinical judgment, this new LMA may allow a simple means of achieving this goal without the use of costly devices (manometers) in every operating room. In 95% of the LMA's tested, the color reading correlated appropriately with the intracuff pressure.

A simple method of partial inflation of the LMA cuff before insertion in children to allow cuff pressure without adjustment after insertion

Background

The cuff of the laryngeal mask airway (LMA) is preferred to be partially inflated before insertion in pediatric cases. However, it is not known how much inflation is appropriate. In addition, intra-cuff pressure is not routinely monitored in many institutions despite the fact that a neglected high cuff pressure could cause several complications. This study was conducted to determine whether the cuff inflated with its resting volume before insertion could have a clinically tolerable intra-cuff pressure after insertion.

Methods

One hundred fifty unpremedicated children aged 0 to 9 yrs were enrolled. The pilot balloon valve was connected to a piston-free syringe to keep the valve open to the atmosphere and allowing the pressure within the cuff of to LMA to equalize to atmospheric pressure. Anesthesia was induced with 6 vol% of sevoflurane in oxygen. After insertion and final positioning of the LMA, the intra-cuff pressure was measured using a cuff pressure manometer.

Results

The mean intra-cuff pressure was 50 ± 12.9 cmH₂O; intra-cuff pressures were 39.1 ± 9.3, 51.6 ± 11.2, and 64.6 ± 12.5 cmH₂O for LMAs of sizes 1.5, 2, and 2.5, respectively. Intra-cuff pressure of more than 60 cmH₂O was measured in 26 patients, and the median value was 70 cmH₂O. There was weak statistical correlation among age, height, and weight with intra-cuff pressure.

Conclusions

The cuff inflated by the resting volume before insertion may be a simple method for guaranteeing tolerable cuff pressure after insertion.

The laryngeal mask in infants and children: what is the cuff pressure?

BACKGROUND

Unintended hyperinflation of the cuff of a laryngeal mask airway (LMA) has been associated with increased airway morbidity and postoperative pain. While the manufacturers recommend a cuff pressure of less than 60 cmH(2)O, in usual clinical practice, there is no method used to determine intracuff pressure of an LMA. The purpose of this prospective quality assurance study is to evaluate the incidence of LMA hyperinflation and excessive intracuff pressure in a busy tertiary care pediatric hospital.

METHODS

There was no change dictated in clinical practice for these patients. Per our usual practice, the LMA was removed from the package and inserted with the cuff partially inflated. The cuff was further inflated as needed to ensure a seal during positive pressure ventilation to a peak inflating pressure of 20-25 cmH(2)O. During the first 30 min of the case, the pressure in the cuff of the LMA was measured using a hand held manometer. Additional data collected included the patient's demographic data (age, weight, and gender), the size of the ETT, and whether nitrous oxide was in use.

RESULTS

Of the 200 subjects in the current study, 106 had an LMA cuff pressure ≥ 60 cmH(2)O (53%). Patients who were greater than 8 years of age had significantly higher average cuff pressures and significantly more LMAs with an intracuff pressure ≥ 60 cmH(2)O when compared to patients younger than 4 years of age and patients 4-8 years of age. Similarly, larger LMAs were found to have significantly higher intracuff pressures.

CONCLUSIONS

Using current clinical practice to inflate the cuff of the LMA, a significant percentage of pediatric patients have an intracuff pressure greater than the generally recommended upper limit of 60 cmH(2)O. Risk factors identified in our study included age of the patient and the size of the LMA.

Effect of Continuous Cuff Pressure Regulator in General Anaesthesia with Laryngeal Mask Airway

Postoperative pharyngolaryngeal complications (PPLC) occur during anaesthesia due to increased cuff pressure following the insertion of laryngeal mask airways. The use of a pressure regulator to prevent PPLC was evaluated in a prospective, randomized study. Sixty patients scheduled to receive general anaesthesia were randomly assigned to two equal groups of 30, either with or without the regulator. The ‘just seal’ cuff pressure (JSCP), cuff pressure at 5-min intervals during anaesthesia, incidence of pharyngeal sore throat (PST), dysphagia, dysphonia and other complications were evaluated at 1 and 24 h postoperatively. The combined mean ± SD JSCP of both groups was 20.3 ± 3.2 mmHg. In the group with the regulator, cuff pressure was maintained at a constant level during anaesthesia. This study demonstrated that the regulator is a simple, functional device that can reduce the incidence of PST significantly at 1 h postoperatively, following general anaesthesia.

Incidence of sore throat in children following use of flexible laryngeal mask airways - impact of an introducer device

BACKGROUND

Insertion of a flexible laryngeal mask airway (FLMA) is more difficult and therefore might result in a higher risk for trauma to the upper airway. To facilitate the insertion of FLMA, the use of an introducer device (Portex Limited, Hythe, Kent, UK) was promoted. However, the impact of the use of this device on the occurrence of postoperative sore throat is unknown.

METHODS

Four hundred children (3-21 years) undergoing elective ambulatory surgery were consecutively included in this study. In 196 cases, the FLMA was inserted using an introducer device. The FLMA cuff was then inflated and the pressure adjusted to below 60 cmH(2)O (according to manufacturers guidelines) using a calibrated cuff manometer (Portex Limited). Three types of FLMA were available: FLMA classic, FLMA unique (both FLMA PacMed, Richmond, Victoria, Australia) and FLMA ProBreathe (Well Lead Medical Co Ltd., Hualong, Guangzhou, China). Prior to discharge, patients' pain was assessed using an age appropriate scale.

RESULTS

Thirteen children (3.3%) developed sore throat, two (0.5%) sore neck and three (0.75%) sore jaw. Of those that developed sore throat, seven had a FLMA inserted with an introducer, six without an introducer. Using a laryngeal mask airways (LMA) with a polyvinyl chloride (PVC), surface was associated with a higher risk for sore throat compared with an LMA with a silicone surface (P = 0.0002).

CONCLUSION

In this study with controlled low cuff pressures, the incidence of sore throat was low. The use of an introducer device did not affect the rate of sore throat.

Reduced air leakage by adjusting the cuff pressure in pediatric laryngeal mask airways during spontaneous ventilation

BACKGROUND

Optimal inflation of the laryngeal mask airway (LMA) cuff should allow ventilation with low leakage volumes and minimal airway morbidity. Manufacturer's recommendations vary, and clinical end-points have been shown to be associated with cuff hyperinflation and increased leak around the LMA. However, measurement of the intra-cuff pressure of the LMA is not routine in most pediatric institutions, and the optimal intra-cuff pressure in the LMA has not been determined in clinical studies.

METHODS

This was a prospective audit in 100 pediatric patients undergoing elective general anesthesia breathing spontaneously via LMA (size 1.5-3). Cuff pressure within the LMA was adjusted using a calibrated pressure gauge to three different values (60, 40, and 20 cmH2O) within the manufacturers' recommended LMA cuff pressure range (< or = 60 cmH2O). Three corresponding inspiratory and expiratory tidal volumes were recorded, and the differences were calculated as the 'leak volume'.

RESULTS

Compared with 20 and 60 cmH2O intra-cuff pressure, measured leakage volumes were the lowest at cuff inflation pressures of 40 cmH2O [median (range) 0.42 (0.09-1.00) ml x kg(-1)] in most patients (83%), while 17% of children demonstrated minimally smaller leakages at 20 cmH2O [0.51 (0.11-1.79) ml x kg(-1)]. Maximum leakage values occurred with cuff pressures of 60 cmH2O in all groups [0.65 (0.18-1.27) ml x kg(-1)] and were not associated with the smallest value of air leakage in any patient.

CONCLUSION

Using cuff manometry, an intra-cuff pressure of 40 cmH2O was associated with reduced leak around the LMA while higher (60 cmH2O) and lower (20 cmH2O) cuff pressures resulted in higher leak volumes during spontaneous ventilation. In spontaneously breathing children, reducing the intra-cuff pressure of pediatric-sized LMAs even below the manufacturers' recommendations allows ventilation with minimized leakage around the LMA cuff.

Laryngeal mask airways--to inflate or to deflate after insertion?

BACKGROUND

Hyperinflation of the laryngeal mask airway (LMA) cuff is known to be a risk factor for airway morbidity and increased leakage around the LMA. While the manufacturers' recommendation is to inflate the cuff with the maximum recommended volumes and/or to adjust the cuff pressure to <60 cmH2O, cuff pressures below 40 cmH2O have been shown to be associated with a minimal rate of sore throat and minimal leakage. However, it remains to be determined whether inflation or deflation is needed to achieve favorable pressures. Therefore, we assessed the need for cuff-volume adjustment following insertion of the LMA unchanged straight from the sterile packaging in a prospective audit.

METHODS

One thousand children (0-16 years) undergoing elective surgery were consecutively included in this quality of care audit. After taking the LMA from its sterile packaging, the LMA cuff was emptied and the amount of air recorded. Then, the same amount of air was returned into the LMA, the LMA was inserted into the patient, and the cuff pressure was measured using a calibrated cuff manometer.

RESULTS

Following insertion of the LMA (without further inflation or deflation of the cuff), 20.5% of children had cuff pressures > or = 60 cmH2, while 55.7% had LMA cuff pressures <40 cmH2O. Cuff pressures were also significantly higher in size 1 LMAs (66.6% had cuff pressures > or = 60 cmH2O and 2% <40 cmH2O) compared with all other sizes (P < 0.05). Furthermore, cuff pressures in LMAs with a poly vinyl chloride (PVC) surface were higher compared to LMAs with a silicone surface (65.2% > or = 60 cmH2O and 9.3% <40 cmH2O vs 9% > or = 60 cmH2O and 67.6% <40 cmH2O, respectively).

CONCLUSIONS

This study demonstrates that LMAs, particularly when using small-sized LMAs or LMAs with a more rigid PVC surface, need to be deflated following insertion of the device rather than inflated to avoid cuff hyperinflation. Hence, cuff pressures should be measured routinely using a manometer to minimize potential pressure-related airway complications.

Impact of laryngeal mask airway cuff pressures on the incidence of sore throat in children

BACKGROUND

Hyperinflation of laryngeal mask airway cuffs can cause harm to the upper airway mainly by exerting high pressures on pharyngeal and laryngeal structures thus impairing mucosal perfusion. Although cuff manometers can be used to guide the monitoring of cuff pressures, their use is not routine in many institutions. In a prospective audit, we assessed the incidence of sore throat following day-case-surgery in relation to the intracuff pressure within the laryngeal mask airway.

METHODS

Four hundred children (3-21 years) were consecutively included in this study. The laryngeal mask airway was inflated as deemed necessary by the attending anesthetist. Cuff pressures were measured using a calibrated cuff manometer (Portex Limited, Hythe, Kent, UK, 0-120 cm H2O, pressures exceeding the measurement range were set at 140 cm H2O for statistical purposes) at induction of anesthesia.

RESULTS

Forty-five children (11.25%) developed sore throat, 32 (8%) sore neck and 17 (4.25%) sore jaw. Of those that developed sore throat, 56.5% had cuff pressures exceeding >100 cm H2O. In contrast, when cuff pressures were <40 cm H2O, there were no episodes of sore throat, whilst there was only a 4.6% occurrence of sore throat if cuff pressures were between 40-60 cm H2O.

CONCLUSION

We have demonstrated that intra cuff pressure in laryngeal mask airways is closely related to the development of sore throat with higher pressures increasing its likelihood. Hence, cuff pressures should be measured routinely using a manometer to minimize the incidence of sore throat.

Insertion techniques of the laryngeal mask airway: a literature review

This article is based on a literature review comparing insertion techniques of the laryngeal mask airway (LMA). I will be looking at the manufacturer's recommended technique and identifying alternative methods, adapted for ease of use, patient comfort or individual circumstances. Risks associated with LMA use will be identified and examples given of research carried out to limit these risks.

Lower cuff pressures improve the seal of pediatric laryngeal mask airways

BACKGROUND

Hyperinflation of laryngeal mask airway (LMA) cuffs may be harmful because of the exertion of high pressures on pharyngeal and laryngeal structures. Although cuff manometers may be used to monitor cuff pressure, their use is not routine in many institutions and clinical endpoints are used instead. Furthermore, it is common clinical practice to add air to the cuff in the presence of an air leak to obtain a better seal.

METHODS

In a prospective audit, the authors assessed air leakage around pediatric sized LMAs (n = 200) following inflation guided by common clinical endpoints (slight outward movement of the LMA) and then following adjustment of the cuff pressure to the recommended pressure range (<60 cmH(2)O) according to institutional guidelines with the use of a calibrated cuff manometer, directly after induction of anesthesia. Following induction, all children were gently ventilated with pressure control ventilation with 10 cmH(2)O and a positive end-expiratory pressure of 5 cmH(2)O.

RESULTS

Following inflation of the cuff guided by clinical endpoints, the median initial cuff pressure (LMA size 1-3) was 92 (size 3) to >120 cmH(2)O (size 1) and the median leakage around the cuff ranged from 0.66 to 1.07 ml x kg(-1). Following cuff pressure adjustment according to the recommended pressure range (<60 cmH(2)O), the leakage decreased significantly to 0.51-0.79 ml x kg(-1) (P = 0.002 for size 1, P < 0.001 for size 1.5-3).

CONCLUSION

The use of clinical endpoints to inflate LMA cuffs is not only associated with significant hyperinflation in the majority of patients but also with an increased leakage around the LMA cuff when compared with adjusted LMA cuff pressures. Therefore, cuff manometers should routinely be used not only to avoid unnecessary hyperinflation but also to improve cuff sealing of LMA in children.

Larynxmaske

Introduction of the laryngeal mask airway (LMA) has been a revolutionary development in airway management over the last decades. It was first used clinically in 1981 by A. Brain and has been widely used in Germany since 1990. Originally intended as a substitute for conventional mask respiration for short periods of general anaesthesia, the laryngeal mask is in the meantime used in many areas as an alternative to elective endotracheal intubation as well as an option for controlling difficult airways. This contribution provides an overview of the basics as well as practical aspects of LMA use, and discusses the possibilities and limitations of the laryngeal mask in daily practice.

A heated humidifier does not reduce laryngopharyngeal complaints after brief laryngeal mask anesthesia

PURPOSE

Warming and humidification of inspired gases is standard care for intubated patients whose lungs are ventilated mechanically for prolonged periods. We examined whether active humidification of inspired gases might reduce laryngo-pharyngeal discomfort in patients undergoing brief laryngeal mask airway (LMA) anesthesia.

METHODS

In a prospective trial, 200 adult patients undergoing elective surgery under general anesthesia were randomly assigned to receive ventilation without airway warming and exogenous humidification (Group C-control), or active warming and humidification of inspired gases (Group HUM-humidified), using a humidifier with a heated wire circuit. Inhalational anesthesia was maintained via a circle system. The temperatures and relative humidities of inspired gases were monitored continuously throughout surgery. Postoperative sore throat, dysphonia, and dysphagia were assessed one and 24 hr after anesthesia. Whenever symptoms were present, their severities were graded using a 101-point numerical rating scale.

RESULTS

The mean temperature and relative humidity of the inspired gases in Group HUM were greater compared to Group C (36.1+/-0.4 degrees C and 99.5+/-0.5% vs 26.9+/-0.8 degrees C and 76.4+/-10.9%, respectively). Postoperatively, the overall frequencies of laryngeal and pharyngeal discomfort were similar in the two groups (53.8% and 54.9% in Group C vs 51.6% and 41.9% in Group HUM at one and 24 hr respectively, P>0.05). The groups were also similar with respect to the severity scores of laryngo-pharyngeal discomfort.

CONCLUSION

Active warming and humidification of inspired gases has no clinically appreciable effect in reducing the incidence and severity of laryngo-pharyngeal complaints after brief (<two hours) LMA anesthesia.

[Oropharyngeal ulcers following anaesthesia with the laryngeal tube S]

We report a case of acute tongue and uvula ulcerations consecutive to the use of a laryngeal tube Sonda (LTS) for airway management. The LTS was used during general anaesthesia for hysteroscopy and resection of endometrial hyperplasia. No trouble occurred during LTS insertion and anaesthesia. Symptomatic treatment provided complete resolution within a few days. This event points out the potential risk of more serious lesions.

Cuff filling volumes and pressures in pediatric laryngeal mask airways

BACKGROUND

Hyperinflation of LMA cuffs carries the risk of airway morbidity by exerting pressure on laryngeal and pharyngeal structures. Cuff hyperinflation in LMAs can result from nitrous oxide diffusion into the LMA cuff and from deliberate manual cuff inflation.

METHODS

In an in vitro set up, maximum recommended cuff filling volumes for size 1, 1.5, 2, 2.5, 3 disposable LMAs from different manufacturers [SoftSeal LMA (Portex); Unique LMA (Intavent); Marshall LAD, LaryngoSeal (Tyco)] and reusable Classic and ProSeal LMAs (Intavent) were inflated into completely emptied LMA-cuffs and into LMA-cuffs at resting volume. Cuff pressures were measured using a cuff manometer. Experiments were performed eight times using two exemplars of each brand/size.

RESULTS

Maximum recommended cuff filling volumes for pediatric LMAs resulted in hyperinflation (cuff pressure >60 cmH(2)O) in almost all LMAs, starting with emptied cuff. Starting from resting cuff volume, the maximum recommended inflation volume resulted in cuff pressures of >120 cmH(2)O in all LMAs and sizes except in the ProSeal size 3 (101 +/- 1 cmH(2)O).

CONCLUSIONS

Since the volume of air which is effectively required depends on several factors and varies between patients, the cuffs should be inflated only with the minimum volume of air required to form an effective seal with the respiratory and gastrointestinal tracts and the cuff pressure should be controlled.

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.

[Lesions to lips, oral and nasal cavities, pharynx, larynx, trachea and esophagus due to endotracheal intubation and its alternatives]

Dysphagia of greater than 48 h duration is an indication for indirect laryngoscopy and when odynophagia and otalgia occur simultaneously, the possibility of subluxation of the arytenoids demands an urgent ENT assessment. The potential seriousness of laryngeal lesions following intubation obliges us to use the smallest compatible endotracheal tube. The occurrence of pain cervical surgical emphysema and fever suggests a pharyngeal lesion necessitating the suspension of oral feeding and the initiation of antibiotic therapy with anaerobic activity, while awaiting possible surgical intervention. There is no argument to use a tooth-guard for each intubation, but tooth fragility must be researched. The incidence of nasal fossa trauma is reduced with the use of nasal packs impregnated with local anaesthetic containing a vasoconstrictor. This allows the introduction of a small flexible lubricated tube. Laryngeal mask-induced sore throat is more common than the more serious injuries. The classical technique of introducing a laryngeal mask of appropriate size (4 for women, 5 for men) in which the cuff is inflated to a leak pressure of 20 cm H(2)O reduces this frequency. The facial mask may cause injuries especially with prolonged use. The incidence of pulmonary aspiration, linked to the action of drugs, raised intra-abdominal pressure; an emergent situation or difficult intubation is decreased with the performance of the Sellick maneuver at intubation, rapid induction and the neutralization of gastric acidity. A meticulous technique of insertion of the, individualized anaesthesia, particular vigilance at the time of decurarisation and position changes and a calm awakening assure its optimal use, unless the Proseal laryngeal mask modifies this point of view.

Postoperative sore throat after ambulatory surgery

BACKGROUND

Sore throat is a common complication of anaesthesia that affects patient satisfaction after surgery.

METHODS

We studied 5264 ambulatory surgical patients prospectively to determine the patient, anaesthetic, and surgical factors associated with sore throat.

RESULTS

In 5264 patients, 12.1% reported a sore throat. Patients with tracheal tube had the greatest incidence, 45.4%, followed by patients with laryngeal mask airway, 17.5%, while patients with a facemask had a lower incidence of sore throat, 3.3%. Female patients had more sore throats than male patients (13.4 vs 9.1%). Airway management had the strongest influence on the incidence of sore throat. Sore throat in ambulatory surgical patients was associated with female sex, younger patients, use of succinylcholine, and gynaecological surgery.

CONCLUSION

Airway management, female sex, younger patients, surgery for gynaecological procedure, and succinylcholine predicts postoperative sore throat. Increased awareness of the predictive factors can help to avoid this combination and improve patient satisfaction.

High laryngeal mask airway pressures resulting from nitrous oxide do not increase pharyngeal mucosal injury in dogs

PURPOSE

During general anesthesia, nitrous oxide (N2O) diffuses rapidly into the air-filled laryngeal mask airway (LMA) cuff, increasing intracuff pressure. There is no clear correlation between LMA intracuff pressure and pressure on the pharynx. We have studied the effects of high LMA intracuff pressures secondary to N2O on the pharyngeal mucosa of dogs.

METHODS

Sixteen mongrel dogs were randomly allocated to two groups: G1 (intracuff volume, 30 mL; n=8) breathed a mixture of O2 (l L x min(-1)) and air (l L x min(-1)) and G2 (intracuff volume, 30 mL; n=8) a mixture of O2 (l L x min(-1)) and N2O (l L x min(-1)). Anesthesia was induced and maintained with pentobarbitone. LMA cuff pressure was measured at zero (control), 30, 60, 90 and 120 min after #4 LMA insertion. The dogs were sacrificed, and biopsy specimens from seven predetermined areas of the pharynx in contact with the LMA cuff were collected for light (LM) and scanning electron microscopic (SEM) examination by a blinded observer.

RESULTS

LMA intracuff pressure decreased with time in G1 (P <0.001) and increased in G2 (P <0.001). There was a significant difference between the groups (P <0.001). In both groups, the LM study showed a normal epithelium covering the pharyngeal mucosa and mild congestion in the subepithelial layer. There were no differences between the groups (P >0.10) or among the areas sampled (P >0.05). In both groups, the SEM study showed a normal pharyngeal mucosa with mild superficial desquamation. Few specimens in G1 and G2 showed more intense epithelial desquamation.

CONCLUSION

High LMA intracuff pressures produced by N2O do not increase pharyngeal mucosal injury in dogs.