The laryngeal mask airway: its features, effects and role

Dynamic parameters of fluid responsiveness in the operating room : An analysis of intraoperative ventilation framework conditions

BACKGROUND

Reliable assessment of fluid responsiveness with pulse pressure variation (PPV) depends on certain ventilation-related preconditions; however, some of these requirements are in contrast with recommendations for protective ventilation.

OBJECTIVE

The aim of this study was to evaluate the applicability of PPV in patients undergoing non-cardiac surgery by retrospectively analyzing intraoperative ventilation data.

MATERIAL AND METHODS

Intraoperative ventilation data from three large medical centers in Germany and Switzerland from January to December 2018 were extracted from electronic patient records and pseudonymized; 10,334 complete data sets were analyzed with respect to the ventilation parameters set as well as demographic and medical data.

RESULTS

In 6.3% of the 3398 included anesthesia records, patients were ventilated with mean tidal volumes (mTV) > 8 ml/kg predicted body weight (PBW). These would qualify for PPV-based hemodynamic assessment, but the majority were ventilated with lower mTVs. In patients who underwent abdominal surgery (75.5% of analyzed cases), mTVs > 8 ml/kg PBW were used in 5.5% of cases, which did not differ between laparoscopic (44.9%) and open (55.1%) approaches. Other obstacles to the use of PPV, such as elevated positive end-expiratory pressure (PEEP) or increased respiratory rate, were also identified. Of all the cases 6.0% were ventilated with a mTV of > 8 ml/kg PBW and a PEEP of 5-10 cmH2O and 0.3% were ventilated with a mTV > 8 ml/kg PBW and a PEEP of > 10 cmH2O.

CONCLUSION

The data suggest that only few patients meet the currently defined TV (of > 8 ml/kg PBW) for assessment of fluid responsiveness using PPV during surgery.

Remimazolam: a randomized controlled study of its suitability for insertion of a supraglottic airway

PURPOSE

Loss of motor response to thrusting the jaw forward is a useful indicator for uncomplicated insertion of a supraglottic airway. The aim of this study was to assess the suitability of remimazolam for insertion of a supraglottic airway assessed by loss of response to jaw thrusting.

METHODS

Seventy patients, who were scheduled for elective surgeries under general anesthesia, were allocated randomly to one of two groups. In one group (remimazolam group), remimazolam was infused 12 mg kg-1 h-1 (50 mg maximum), and in the other (propofol group), propofol was infused at 120 mg kg-1 h-1 (500 mg maximum). Once the eyelash reflex disappeared, response to jaw thrusting was assessed. Primary outcome measure was the proportion of patients with loss of response to jaw thrusting before reaching the maximum dose of the test drug. We planned an interim analysis (of one time) after 40 patients, using the Pocock adjustment method.

RESULTS

From the interim analysis results, the study was stopped after recruitment of 40 patients. Loss of response to jaw thrusting was observed in all of 21 patients (100%) in the propofol group, and in 9 of 19 patients (47%) in the remimazolam group. There was a significant difference in the proportion between the groups (P = 0.0001, 95% CI for difference 30-75%).

CONCLUSION

Remimazolam frequently does not inhibit response to jaw thrusting, and thus remimazolam is not a suitable induction agent for uncomplicated insertion of a supraglottic airway unless either a neuromuscular blocking agent or an opioid is co-administered.

Intravenous fentanyl vs. topical lignocaine for ProSeal™ laryngeal mask airway insertion with propofol induction

Insertion of the laryngeal mask airway (LMA) without muscle relaxant requires adequate obtundation of airway reflexes, which may otherwise lead to incorrect or failed LMA placement. This study compared topical lignocaine spray vs. intravenous (IV) fentanyl, during propofol induction for insertion of the ProSeal™ LMA (PLMA). This was a prospective, randomized, double blind study, in ASA I or II patients, for elective or emergency surgery. Seventy patients (n = 70) who fulfilled the inclusion criteria were randomly assigned to receive IV fentanyl 2 mcg/kg or topical lignocaine spray 40 mg, prior to anesthesia induction with IV propofol (2–2.5 mg/kg). ProSeal™ LMA insertion condition was regarded optimal in the absence of adverse responses (gag, cough, laryngospasm and body movements), and successful LMA placement at the first attempt. Hemodynamic parameters were recorded and patients were assessed for sore throat and hoarseness post operatively. Seventy patients were analyzed. The number of patients with optimal PLMA insertion conditions were comparable between the groups (60% vs. 57%, P = 0.808). All hemodynamic parameters were comparable between groups with the exception of heart rate. Sympathetic obtundation of heart rate was greater with IV fentanyl than topical lignocaine (P < 0.05). The proportion of patients with postoperative sore throat significantly increased with the number of insertion attempts (P < 0.05). Topical lignocaine spray to the pharynx is as effective, and may be an alternative to IV fentanyl, during propofol induction for PLMA insertion. Success rate and optimal insertion condition at the first attempt, propofol requirement, blood pressure, adverse events and airway complications were comparable. Heart rate obtundation was less with topical lignocaine spray but remained within clinically acceptable values.

A new maneuver for classical laryngeal mask airway insertion: Prospective randomized study

Background/Aim: Laryngeal mask airway (LMA) has been frequently used for airway management. But the satisfaction of the insertion and trauma at insertion remain problems. We present a new insertion maneuver for classical LMA (cLMA) with a partially inflated cuff and examine its success and complication rate. Methods: In 4 months, 158 patients who were classified as ASA I–III and older than 18 years old and were planned for LMA were included in this study consecutively (according to the study design, one patient was excluded during the study). Emergency cases, patients with any contraindications with LMA, patients who were expected to undergo surgery for more than 2 h, patients with preoperative respiratory tract infection or sore throat, patients undergoing oral or nasal surgery, and patients with aspirated oropharyngeal secretions after removal of LMA was excluded from the study. Age, gender, height, weight, ASA scores, comorbidities, and the duration of anesthesia and surgery of the patients were recorded. One-hundred-fifty-seven consecutive patients were randomized into two groups by a coin toss [control group (group C) and study group (group S)]. The groups were compared in terms of LMA insertion success, the number of insertion attempts, the presence of blood on the LMA or in secretions, and postoperative sore throat. Classical Laryngeal Mask Airway was inserted with Brain’s standard technique in group C and with the new technique in group S. In the new technique, the head and neck of the patient were supported in a straight position, the mouth was opened, cLMA was held with a dominant hand from the tube part and inserted until the tip touches to the oropharynx. The index finger of the non-dominant hand was inserted into the mouth to pass by the cLMA and reach the tip of the cLMA. The tip of cLMA was directed to the caudal by the index finger. Then, cLMA was inserted by the guidance of the index finger until it reached the triangular base of the oropharynx. Results: There was no statistically significant difference in terms of demographic data and placement success; placement success was better in the study group (100% versus 98.6% and P = 0.45). Similarly, the count of attempts was better in the study group. The mean attempt number was 1.11 in group S and 1.28 in group C (P = 0.02). Also, blood on LMA was seen to be more common in group C (P = 0.04). There were no statistical differences in sore throat, but it was less seen in group S. Conclusion: The new maneuver was better than the standard technique and easy to use in daily practice.

Validation of manufacturers' laryngeal mask airway size selection standard: a large retrospective study

Background

Laryngeal mask airway (LMA) is a prominent supraglottic airway device, widely used especially in difficult airway management. However, the LMA sizes recommended by the manufacturers are not always well matched in clinical practice, which leads to complications. To date, there are rare models to validate whether the manufacturers’ standard is suitable for use in clinical practice.

Methods

A total of 58,956 patients undergoing general anesthesia using LMA device were included in the study between January 1, 2011 and December 31, 2018, to validate the adherence rate of LMA sizes according to the manufacturers’ recommendations. A logistic regression analysis was performed based on the actual LMA size used in clinical practice to establish separately size selection guidelines with gender, weight, and age as variables in adults, adolescents, and children.

Results

LMA insertions were analyzed in 50,776 (86.1%) adults, 3,548 (6%) adolescents, and 4,632 (7.9%) children. Suitability of manufacturers’ recommendations was higher in children [male: 86.02%; female: 85.09%] than adults [male: 72.75%; female: 78.13%] or adolescents [male: 73.4%; female: 70.79%]. For adults and adolescents, LMA size was better predicted using the regression model rather than the manufacturers’ recommendations [male adults: 82.4% (81.16–83.57%) vs. 73.21% (71.79–74.59%), P<0.05; female adults: 87.82% (86.65–88.9%) vs. 77.07% (75.6–78.48%), P<0.05; male adolescents: 79.45% (74.86–83.4%) vs. 72.05% (67.09–76.53%), P<0.05; female adolescents: 78.4% (71.11–84.31%) vs. 72.22% (64.54–78.82%), P<0.05]. For children, there was equal performance suitability using the regression model and the manufacturers’ recommendations.

Conclusions

The model-based guidelines may provide more accurate directions for LMA size selection for adolescents and adults than the manufacturers’ weight-based recommendations, whereas the manufacturers’ recommendation in children is consistent with clinical practice.

Effect of Laryngeal Mask Air Way Insertion versus Endotracheal Intubation over Hemodynamic Responses in Pediatrics Patient Who Underwent Ophthalmic Surgery at Menelik II Hospital, Addis Ababa: A Prospective Observational Study Design

Background

The airway of an anesthetized child is usually maintained with an endotracheal tube or laryngeal mask airway. However, both are related with some level of pressor response which may be risky in several groups of patient.

Methods

An institutional-based prospective observational study design was employed. A systematic random sampling technique was used to select study participants. Data were entered into Epi info version 7 and transported to SPSS version 20 for analysis. Normality of the data was checked using Shapiro-Wilk tests. An independent t test was used to determine the mean differences between the two groups while the paired sample t test was used to determine the mean differences within the groups. A p value of less than 0.05 was used as a cut-off point for the presence of association.

Results

The changes in systolic and diastolic blood pressure were returned to baseline values at five and three minutes in both groups, respectively. However, the changes in the heart rate and mean arterial pressure returned to baseline values in five minutes in the ETT group and three minutes in the LMA group. At baseline, the difference in systolic blood pressure between the two groups was not statistically significant (p=0.328).

Conclusions

A significant hemodynamic pressor response was observed after the insertion of both LMA and ETT groups. However, the LMA group has less hemodynamic change as compared to the ETT group. Therefore, the practice of LMA insertion was strongly recommended.

Comparison of LM-Supreme™ and endotracheal tube in patients undergoing gynecological laparoscopic surgery

While laryngeal mask is widely used for laparoscopic interventions in some countries, concerns exist regarding pulmonary aspiration and inadequate ventilation. We compared the LM-Supreme™ (LM-S) with the endotracheal tube (ETT) for laparoscopic gynecological interventions in terms of ventilation parameters and gastric distention. This prospective randomized and double-blind study. The patients were divided into two groups: ETT (n = 50) and LM-S group (n = 50). All patients in the LM-S and ETT groups recieved total intravenous general anaesthesia and standard ventilation protocols. Ventilation parameters (airway peak pressure, mean airway pressure, end-tidal carbon dioxide, total volume, oropharyngeal leak pressure) and perioperative laryngopharyngeal morbidity were recorded before peritoneal insufflation, during and after the peroperative period. The mean airway pressure values in the ETT group 2 min after airway device insertion were significantly higher. The gastric distension after the laparoscope entered the abdomen in the LM-S group was found to be significantly lower. In the first hour postoperative sore throat, disphonia and dysphagia were statistically significantly higher in the ETT group. In our study we concluded that LM-S provides reliable endotracheal intubation in ASA I & II patients undergoing laparoscopic gynecological surgery under positive pressure ventilation.ClinicalTrials.gov ID NCT02127632.

Prediction of failed facemask ventilation: new scoring system for difficult airway

BACKGROUND

We previously have shown that there was a strong correlation between failed facemask ventilation, failed ventilation through a supraglottic airway, and difficult tracheal intubation. The primary aim of this study was to evaluate whether or not an established method to predict difficult ventilation through a supraglottic airway was also useful for predicting failed facemask ventilation.

METHODS

This was a single-center, retrospective observational study. We studied 28,081 anesthetized patients in whom ventilation through a facemask, and supraglottic airway was attempted as the initial technique during induction of anesthesia, between May 2011 and March 2016. For each patient, the score which had been validated to be useful for predicting difficult ventilation through a supraglottic airway was calculated. The score ranged between 0 and 7 points, and we defined a low risk when the score was 0-3, and a high risk when the score was 4-7. To measure and compare the predictive accuracy of the score, we generated a receiver operating characteristic curve and compared the area under the curve (AUC).

RESULTS

The incidence of failed facemask ventilation was significantly higher in patients with high-risk predictive score than in patients with low-risk predictive score [0.38% vs 0.056%, odds ratio 6.8 (95% CI 2.6-18.1, p value = 0.002)], and the sensitivity of the score was 25%, while the specificity was 95%, with a negative predictive value of 99%. The AUC of the score was 0.71 (95% CI 0.58-0.83).

CONCLUSIONS

The predictive score for difficult ventilation through a supraglottic airway is also useful to predict failed facemask ventilation.

Comparison of Laryngeal Mask Airway with Tracheal Tube for Ophthalmic Surgery in Paediatric Patients

This study of sixty ASA grade 1 or 2 children, aged 1 to 12 years, undergoing elective ophthalmic procedures, compared the use of the laryngeal mask airway (LMA) with that of an endotracheal tube. Changes in intraocular pressure and haemodynamic parameters, and intraoperative and postoperative complications were measured. Patients were randomly allocated into two groups of 30 patients. In group 1, the airway was secured with an LMA and in group 2 with an endotracheal tube. A standard technique of general anaesthesia incorporating positive pressure ventilation was used in both groups. The changes in intraocular pressure, heart rate (HR) and mean arterial pressure (MAP) were observed before and after insertion of the airway device, two minutes after insertion, and pre and post removal of the device. The incidence of airway complications was also noted. There was no significant change in mean intraocular pressure after insertion of the LMA, but removal caused a significant increase to 19.3± 7.6 mmHg (from a baseline of 13.9±4.3 mmHg). In the endotracheal tube group, intubation increased the mean intraocular pressure significantly to 19.9±7.3 mmHg (from a baseline of 13.1±4.0 mmHg) and extubation caused an increase to 24.6±10.4 mmHg which was clinically as well as statistically significant. The incidence of postoperative coughing was lower in the LMA group, but the incidence of vomiting higher. Two patients had displacement of the LMA during the procedure. We conclude that the use of an LMA is associated with less increase in intraocular pressure than the use of an endotracheal tube in children.

Comparison of cervical spine motion during intubation with a C‑MAC D‑Blade® and an LMA Fastrach®

BACKGROUND

This prospective randomized study compared cervical motion during intubation with a C‑MAC D‑Blade® and with a laryngeal mask airway LMA Fastrach®.

MATERIAL AND METHODS

The participants in this study were 52 ASA I-III patients aged 18-70 years and assigned for elective cervical discectomy. The patients were randomly selected for intubation with a C‑MAC D‑Blade® (group V) or an LMA Fastrach® laryngeal airway (group F). Both groups received the same induction of anaesthesia. The first lateral view was X‑rayed while the head and neck were in a neutral supine position and the second exposure was taken during the passage of the endotracheal tube through the vocal cords for group V and during the advance of the endotracheal tube for group F. The occiput-C1 (C0-C1), C1-C2 and C2-5 angles were measured. The angle formed by the line between the occipital protuberance and anterior process of the foramen magnum and the line between the central point of C1 spinous process and the anterior process of the foramen magnum was defined as angle A. The differences between the angles were calculated. Overall intubation success and first-pass success (success at the first attempt) were recorded.

RESULTS

The change in angulations between C0-C1 during intubation was significantly lower in group F than in group V (2.78⁰ ± 2.1⁰ vs. 6.04⁰ ± 4.1⁰, p = 0.007). Before intubation, angle A was 14.4⁰ ± 3.9⁰ in group V and 13.8⁰ ± 3.7⁰ in group F (p = 0.627). During intubation, angle A was significantly smaller for group V than for group F (9.1⁰ ± 2.4⁰ vs. 10.7⁰ ± 2.9⁰, p = 0.04). The number of successful intubations were significantly higher in group V (100% of intubations were successful on the first attempt for group V, vs. 80% for group F, p = 0.023).

CONCLUSION

Intubation with both a C‑MAC D‑Blade and a Fastrach LMA resulted in cervical motion but within safe ranges. Intubation with a C-mac D blade might be preferred because the Fastrach LMA may result in more failed intubation attempts in patients with cervical spine disorders.

Effect of immobilised cervical spine on oropharyngeal sealing pressure with Ambu AuraGain™ Supraglottic airway: A randomised crossover trial

Background and Aims:

Ambu^® AuraGain™ laryngeal airway (AuraGain) is one of the newer supraglottic airway device introduced in 2014. Cervical spine stabilisation with hard cervical collar makes insertion of supraglottic airways and tracheal intubation difficult. This study was conducted to investigate whether the presence of a cervical collar affects the oropharyngeal sealing pressure (OSP) and fibreoptic view of the glottis (Brimacombe score) in airways secured with the AuraGain.

Methods:

The study was a randomised crossover trial. Thirty five ASA 1-3 patients undergoing elective surgery under general anaesthesia were recruited for the study. In each patient AuraGain was inserted twice in a crossover manner once with and once without a hard cervical collar in situ, with the sequence of insertion randomised. During each insertion of AuraGain the OSP, fibreoptic view of the glottis, insertion parameters, ventilator data and complications were noted.

Results:

The mean OSPs in both the groups were similar with no significant difference (29.6 ± 3.7 cmH₂O without collar and 30.1 ± 3.1 cmH₂O with collar [P = 0.310]). The fibreoptic view of glottis was also similar in both groups. The insertion with collar was more difficult than without collar. The number of attempts for successful insertion was same in both the groups. The time taken for appropriate placement of LMA was significantly prolonged in patients with collar.

Conclusions:

We conclude that the Ambu AuraGain can be used to provide effective ventilation in patients whose cervical spine is immobilised with a hard cervical collar.

Recent advances and anaesthetic considerations in corneal transplantation

Significant surgical advances have been made recently in corneal transplantation. Penetrating keratoplasty was the dominant method from 1905, until selective lamellar keratoplasty emerged as the preferred technique over the last 20 years. Advanced techniques such as corneal limbal stem cell transplant and keratoprosthesis are also available. The major surgical complications of corneal transplantation are extrusion of ocular content and expulsive choroidal haemorrhage. It is essential for an ophthalmic anaesthetist to have a good understanding of these new surgical procedures so as to provide optimal surgical conditions. This article aims to inform anaesthetists about the recent surgical advances in corneal transplantation and explore the anaesthetic considerations of these new techniques. General anaesthesia remains suitable for a wide range of these procedures especially in repeat surgery, difficult, or prolonged procedures. Regional ophthalmic blocks are ideal for endothelial keratoplasty but can be used in penetrating keratoplasty based on individual risk-benefit assessment, and as a supplement to general anaesthesia. Topical anaesthesia provides an alternative when general anaesthesia and ophthalmic regional blocks are less desirable but overall its use is limited.

Advantages, Disadvantages, Indications, Contraindications and Surgical Technique of Laryngeal Airway Mask

The beauty of the laryngeal mask is that it forms an air tight seal enclosing the larynx rather than plugging the pharynx, and avoid airway obstruction in the oropharynx. The goal of its development was to create an intermediate form of airway management face mask and endotracheal tube. Indication for its use includes any procedure that would normally involve the use of a face mask. The laryngeal mask airway was designed as a new concept in airway management and has been gaining a firm position in anesthetic practice. Despite wide spread use the definitive role of the laryngeal mask airway is yet to be established. In some situations, such as after failed tracheal intubation or in oral surgery its use is controversial. There are several unresolved issues, for example the effect of the laryngeal mask on regurgitation and whether or not cricoids pressure prevents placement of mask. We review the techniques of insertion, details of misplacement, and complications associated with use of the laryngeal mask. We then attempt to clarify the role of laryngeal mask in air way management during anesthesia, discussing the advantages and disadvantages as well as indications and contraindications of its use in oral and maxillofacial surgery.

Role of Laryngeal Mask Airway in Emergency Department and Pre-Hospital Environment

LMA and Intubating LMA (LMA-Fastrach) have been widely used by anesthesiologists in operation theaters and have achieved great success. Its use in the emergency department and pre-hospital setting by EMS has recently been proven to be very successful. It is also a very useful tool in providing a quick airway in case of failed intubation and failed ventilation situations. In this article, some of its use in emergency departments and pre-hospital setting are discussed.

Comparison of trapezius squeeze test and jaw thrust as clinical indicators for laryngeal mask airway insertion in spontaneously breathing children

Background and Aims:

It is not known whether trapezius squeeze test (TPZ) is a better clinical test than jaw thrust (JT) to assess laryngeal mask airway (LMA) insertion conditions in children under sevoflurane anesthesia.

Material and Methods:

After the Institutional Ethics Committee approval and written informed parental consent, 124 American Society of Anesthesiologists I and II children of 2–8 years of age undergoing minor surgical procedures were randomized into TPZ and JT groups. The children were induced with 8% sevoflurane in oxygen at a fresh gas flow of 4 L/min. TPZ or JT was performed after 1 min of start of sevoflurane and then every 20 s till the test was negative, when end-tidal (ET) sevoflurane concentration was noted. Classic LMA of requisite size was inserted by a blinded anesthetist and conditions at the insertion of LMA, insertion time, and the number of attempts of LMA insertion were recorded.

Results:

The mean LMA insertion time was significantly longer (P < 0.001) for TPZ (145 ± 28.7 sec) compared to JT group (111.8 ± 31.0 sec). ET sevoflurane concentration at the time of LMA insertion was comparable in the two groups. LMA insertion conditions were similar in the two groups. There was no difference between the two groups regarding total number of attempts of LMA insertion. Heart rate (HR) decreased in both groups after LMA insertion (P < 0.001) but TPZ group had significantly lower HR compared with the JT group up to 5 min after LMA insertion (P = 0.03).

Conclusion:

Both JT and TPZ are equivalent clinical indicators in predicting the optimal conditions of LMA insertion in spontaneously breathing children; however, it takes a longer time to achieve a negative TPZ squeeze test.

A randomised controlled trial comparing ProSeal laryngeal mask airway, i-gel and Laryngeal Tube Suction-D under general anaesthesia for elective surgical patients requiring controlled ventilation

Background and Aims:

The ProSeal™ laryngeal mask airway (PLMA), i-gel™ and Laryngeal Tube Suction-D (LTS-D™) have previously been evaluated alone or in pair-wise comparisons but differing study designs make it difficult to compare the results. The aim of this study was to compare the clinical performance of these three devices in terms of efficacy and safety in patients receiving mechanical ventilation during elective surgical procedures.

Methods:

This prospective, randomised, double-blind study was conducted on 150 American Society of Anesthesiologists physical status I–II patients, randomly allocated into 3 groups, undergoing elective surgical procedures under general anaesthesia. PLMA, i-gel™ or LTS-D™ appropriate for weight or/and height was inserted. Primary outcome measured was airway sealing pressure. Insertion time, ease of insertion, number of attempts, overall success rate and the incidence of airway trauma and complications were also recorded. Intergroup differences were compared using one-way analysis of variance with post hoc correction for continuous data and Chi-square test for categorical variables.

Results:

Overall success rate was comparable between the three devices (i-gel™ 100%, LTS-D™ 94%, PLMA 96%). Airway sealing pressure was lower with i-gel™ (23.38 ± 2.06 cm H₂O) compared to LTS-D™ (26.06 ± 2.11 cm H₂O) and PLMA (28.5 ± 2.8 cm H₂O; P < 0.0005). The mean insertion time was significantly more in PLMA (38.77 ± 3.2 s) compared to i-gel™ (27.9 ± 2.53 s) and LTS-D™ (21.66 ± 2.31 s; P < 0.0005).

Conclusion:

Airway sealing pressure and insertion time were significantly higher in PLMA compared to i-gel™ and LTS-D™.

Airway Management via Laryngeal Mask in Laryngotracheal Resection

We present a case of impassable subglottic stenosis scheduled for tracheal resection and reconstruction managed by establishing a supraglottic airway. Despite careful preoperative evaluation, the stenosis was localized higher than anticipated, rendering conventional intubation impossible. Laryngeal mask bridging to cross-field ventilation was feasible and jet ventilation and cardiopulmonary bypass were available as emergency strategies. Surgery and emergence went uneventful. Perioperative considerations are discussed in this report.

An Airway Management Device: The Laryngeal Mask Airway—A Review

The laryngeal mask airway (LMA) is an airway management device that has become an accepted part of anesthetic practice in both pediatric and adults surgical patients. It is inserted without the use of a laryngoscope or muscle relaxants into the hypopharynx forming a low pressure seal around the glottis. The LMA provides a better airway than a face mask with or without an oral airway. Insertion techniques are quickly learned and are described in this review. Since the LMA forms a less secure seal than an endotracheal tube (ETT), several important limitations and contraindications exist. This includes patients at high risk for regurgitation of gastric contents into the lungs causing pulmonary aspiration and patients requiring high ventilatory pressures or prolonged ventilation. These contraindications have limited its introduction and utilization in the intensive care unit (ICU). The LMA is a helpful tool in the management of both the expected and unexpected difficult airway, where it may serve both as an emergency airway and as a conduit to intubation of the trachea with an ETT over a fiberoptic bronchoscope (FOB) or gum elastic bougie. A lifesaving airway has been provided by the LMA where no other means of achieving ventilation were possible in patients, including neonates, trauma victims, woman undergoing cesarean section, and in the setting of cardiac arrest. There are very few reported uses of the LMA in the ICU. We believe that familiarity with the LMA's design, use, and limitations by critical care practitioners will increase its use in emergency airway management and in the ICU. The LMA may prove to be the first of a new generation of airway devices placed into the hypopharynx to provide an alternative to the endotracheal tube and mask airway.

Parapharyngeal abscess following use of a laryngeal mask airway during open revision septorhinoplasty

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Laryngeal mask airways have a high rate of success and low rate of complications.

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Parapharyngeal abscesses have not been recently published following LMA use.

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We report a parapharyngeal abscess after uncomplicated LMA use following atraumatic insertion.

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Pressure necrosis from over-inflation is thought to have perforated the pyriform fossa.

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The perforation created a communication into the parapharyngeal space causing infection.

Introduction

A laryngeal mask airway (LMA) is an established safe tool to support the airway during surgery under general anesthetic. It is commonly used both in North America and abroad. Complications with this device are rare.

Presentation of case

A 50-year old female developed a parapharyngeal neck abscess following an uneventful septorhinoplasty during use of an LMA Classic. The patient had symptoms of pain and difficulty swallowing. CT revealed extensive soft tissue edema and swelling in the right and posterior neck involving the right parapharyngeal space, right parotid space, minimal involvement of the right submandibular space, and extending across the retropharyngeal space. The abscess was incised and drained with an open approach, combined with laryngoscopy to evaluate the site of the infection at the right pyriform fossa. The patient fully recovered following discharge.

Discussion

Despite the rare incidence of LMA injuries, early recognition of parapharyngeal neck abscesses can initiate early treatment and prevention of spread to retropharyngeal space where airway obstruction and emergent complications may occur.

Conclusion

Laryngeal mask airways have a high rate of success and low rate of complications. In this reported case, pressure necrosis from over-inflation of the LMA is thought to have perforated the right pyriform fossa. The perforation created a communication into the parapharyngeal space causing infection. We report this case to highlight the importance of identifying possible complications associated with a routine method of airway management during shared airway surgeries.

Safety and efficacy of bronchoalveolar lavage using a laryngeal mask airway in cases of acute hypoxaemic respiratory failure with diffuse lung infiltrates

Objective Fibre-optic bronchoscopy with bronchoalveolar lavage (FOB-BAL) is an important tool for diagnosing and selecting treatment for acutely hypoxaemic patients with diffuse lung infiltrates. However, FOB-BAL carries a risk of significant hypoxaemia and subsequent tracheal intubation during and after the procedure. The application of FOB-BAL using a laryngeal mask airway (LMA) in combination with continuous positive airway pressure (CPAP) may minimize the incidence of hypoxaemia; however, the safety and efficacy of this procedure have not been investigated. Methods A retrospective chart review was performed from April to September 2013. Data regarding the recovered volume of BAL fluid, incidence of tracheal intubation within eight hours after the completion of FOB-BAL, respiratory and haemodynamic parameters and treatment modifications were collected for the evaluation. Results Ten trials of FOB-BAL using an LMA and CPAP were performed in nine patients with severe acute hypoxaemia associated with diffuse lung infiltrates. The BAL fluid recovery rate was 56%, and the procedure was completed without subsequent complications. In addition, the percutaneous arterial oxygen saturation decreased to 95.7%±3.8%, although it was never lower than 90.0% during the procedure, and no patients required intubation. Furthermore, the arterial blood pressure significantly but transiently decreased due to sedation, and the procedure yielded diagnostic information in all nine patients. Conclusion FOB-BAL using LMA and CPAP appears to be safe and effective in patients who develop severe acute hypoxaemia.

Effect of cricoid pressure on placement of the I-gel™ : a randomised study

We studied 40 adult patients to see if cricoid pressure affected placement of the I-gel(™). In a randomised crossover design, the i-gel was placed with and without cricoid pressure, and we compared the success rate of adequate ventilation through the i-gel, time to placement and the rate of optimal position of the device between the two circumstances. Cricoid pressure significantly decreased the success rate of adequate ventilation through the i-gel (40 vs 34 patients) (p = 0.041, 95% CI for difference 4-26%), and significantly decreased the rate of the optimal position (39 vs 17 patients) (p < 0.001). The time to achieve adequate ventilation was significantly longer (p < 0.001) with cricoid pressure than without (median difference 8 s; 95% CI for median difference 3-12 s). Cricoid pressure significantly decreases the success rate of ventilation through the i-gel, but the success rate of ventilation through the i-gel is reasonably high.

Effect of intranasal dexmedetomidine or oral midazolam premedication on sevoflurane EC50 for successful laryngeal mask airway placement in children: a randomized, double-blind, placebo-controlled trial

INTRODUCTION

This study was conducted to determine the effect of oral midazolam (OM) or intranasal dexmedetomidine (IND) on the EC50 of sevoflurane for successful laryngeal mask airway placement in children. We hypothesize that premedication with either agent might reduce the sevoflurane EC50 for laryngeal mask airway placement in children to a similar extent.

METHODS

Fifty-two American Society of Anesthesiologists (ASA) I children (aged 1-6 years) scheduled for general anesthesia with laryngeal mask airway were randomized to one of the three groups: group M received 0.5 mg · kg(-1) OM with honey and intranasal saline, group D received 2 μg · kg(-1) IND along with oral honey, and group P received oral honey and intranasal saline at least 30 min prior to induction of anesthesia. Anesthesia was induced with incremental sevoflurane up to 8% in 100% O2 . A predetermined target endtidal sevoflurane (ETsevo ) concentration (2% in the first child of all three groups) was sustained for 10 min before the attempt of laryngeal mask airway insertion by adjusting dial concentration. No intravenous anesthetic or neuromuscular blockade was used. ETsevo was increased/decreased (step size 0.2%) using Dixon's and Massey's up and down method in next patient depending upon previous patient's response. Placement of the laryngeal mask airway without movement, coughing, biting, or bucking was considered as successful. EC50 of sevoflurane was calculated as the average of the crossover midpoints in each group, which was further confirmed by probit analysis.

RESULTS

The EC50 of sevoflurane for laryngeal mask airway placement after OM (1.66 ± 0.31) and IND (1.57 ± 0.14) premedications was significantly lower than the placebo group (2.00 ± 0.17, P < 0.0001). The EC95 (95% CI) derived from probit regression analysis was 2.34% (2.22-2.51%) with OM, 1.88% (1.77-2.04%) with IND, and 2.39% (2.25-2.35%) with placebo group.

CONCLUSIONS

Oral midazolam and IND premedications significantly reduce the sevoflurane EC50 for laryngeal mask airway insertion in children by 17% and 21%, respectively.

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.

Comparison of the trapezius squeezing test and jaw thrust as indicators for laryngeal mask airway insertion in adults

BACKGROUND

The purpose of this study was to compare the effectiveness of the trapezius squeezing test with that of the jaw thrust maneuver as clinical indicators of adequate conditions for laryngeal mask airway (LMA) insertion in adults under sevoflurane anesthesia.

METHODS

One hundred adult patients of ASA physical status 1 or 2 undergoing minor surgical procedures were randomly allocated to the T (trapezius squeezing, n = 50) group or the J (jaw thrust, n = 50) group. The LMA was inserted immediately after the loss of response to trapezius squeezing or jaw thrust. Successful and unsuccessful attempts were recorded. An unsuccessful attempt was defined as the occurrence of coughing, gagging, gross purposeful movements, breath-holding, laryngospasm, or an SpO(2) < 90% during LMA insertion. Insertion time, end-tidal sevoflurane concentration, mean arterial pressure, and heart rate were recorded.

RESULTS

The incidence of successful attempts was significantly higher in the T than in the J group (48/50 vs. 36/50, respectively).

CONCLUSIONS

The trapezius squeezing test is a superior indicator of an adequate condition for LMA insertion compared to the jaw thrust maneuver in adults under sevoflurane anesthesia.

Equipment to manage a difficult airway during anaesthesia

Airway complications are a leading cause of morbidity and mortality in anaesthesia. Effective management of a difficult airway requires the timely availability of suitable airway equipment. The Australian and New Zealand College of Anaesthetists has recently developed guidelines for the minimum set of equipment needed for the effective management of an unexpected difficult airway (TG4 [2010] www.anzca.edu.au/resources/professionaldocuments). TG4 [2010] is based on expert consensus, underpinned by wide consultation and an extensive review of the available evidence, which is summarised in a Background Paper (TG4 BP [2010] www.anzca.edu.au/ resources/professional-documents). TG4 [2010] will be reviewed at the end of one year and thereafter every five years or more frequently if necessary. The current paper is reproduced directly from the Background Paper (TG4 BP [2010]).

The clinical effectiveness of the streamlined liner of pharyngeal airway (SLIPA) compared with the laryngeal mask airway ProSeal during general anesthesia

Background

The aim of this study was to compare the streamlined liner of the pharynx airway (SLIPA), a new supraglottic airway device (SGA), with the laryngeal mask airway ProSeal™ (PLMA) during general anesthesia.

Methods

Sixty patients were randomly allocated to two groups; a PLMA group (n = 30) or a SLIPA group (n = 30). Ease of use, first insertion success rate, hemodynamic responses to insertion, ventilatory efficiency and positioning confirmed by fiberoptic bronchoscopy were assessed. Lung mechanics data were collected with side stream spirometry at 10 minutes after insertion. We also compared the incidence of blood stain, incidence and severity of postoperative sore throat and other complications.

Results

First attempt success rates were 93.3% and 73.3%, and mean insertion time was 7.3 sec and 10.5 sec in PLMA and SLIPA. There was a significant rise in all of hemodynamic response from the pre-insertion value at one minute following insertion of SLIPA. But, insertion of PLMA was no significant rise in hemodynamic response. There was no statistically significant difference in the mean maximum sealing pressure, gas leakage, lung mechanics data, gastric distension, postoperative sore throat and other complication between the two groups. Blood stain were noted on the surface of the device in 40% (n = 12) in the SLIPA vs. 6.7% (n = 2) in the PLMA.

Conclusions

The SLIPA is a useful alternative to the PLMA and have comparable efficacy and complication rates. If we acquire the skill to use, SLIPA may be considered as primary SGA devices during surgery under general anesthesia.

Topical lidocaine improves conditions for laryngeal mask airway insertion

PURPOSE

We hypothesized that optimal laryngeal mask airway (LMA) insertion conditions might be achieved with topical lidocaine and a smaller dose of propofol. In this study, insertion conditions after topical lidocaine 40 mg followed by propofol 2 mg.kg(-1) were compared with propofol 2 mg.kg(-1) or propofol 3 mg.kg(-1) alone.

METHODS

Ninety patients were recruited for this randomized prospective double-blind study. One group received four sprays of topical lidocaine (40 mg) over the posterior pharyngeal wall followed by propofol 2 mg.kg(-1) (Group 2PL; n = 30). The other two groups received four sprays of 0.9% normal saline followed by propofol 2 mg.kg(-1) (Group 2P; n = 30) or by propofol 3 mg.kg(-1) (Group 3P; n = 30). The frequency of optimal insertion conditions (successful insertion at the first attempt without adverse responses) and side effects were recorded.

RESULTS

The frequency of optimal insertion conditions was greater in Group 2PL (20/30, 67%) and Group 3P (22/30, 73%) than in Group 2P (11/20, 37%) (P = 0.009). In Group 3P, the mean blood pressure was lower than in the other groups prior to LMA-Classic insertion (P = 0.003) but was similar after insertion. The incidence of apnea was greater in Group 3P patients (17/30, 57%) than in Group 2P (2/30, 7%) or Group 2PL patients (1/30, 3%) (P < 0.001).

CONCLUSION

Topical lidocaine 40 mg followed by propofol 2 mg.kg(-1) can provide optimal insertion conditions of the LMA-Classic comparable to those of propofol 3 mg.kg(-1), with fewer hemodynamic changes and a lower incidence of apnea.

[Combined regional-general anesthesia with use of the Proseal laryngeal mask during prolonged peripheral plastic surgery]

The ProSeal laryngeal mask offers a better interface for controlled ventilation than does a traditional mask because of the ProSeal's improved airway seal and the possibility of draining the digestive tract. Limb reconstructive surgery is normally a long procedure involving the use of grafts or flaps located at a distance from the lesion. Regional anesthesia is therefore of limited use. We report a series of 24 adult patients who underwent peripheral plastic surgery under combined regional and general intravenous anesthesia and in whom the ProSeal mask was used. Data recorded included assessment of the airway and intubation difficulty, disease and duration of the procedure, type of regional anesthesia, respiratory and hemodynamic variables, patient satisfaction, laryngeal complications, and postoperative analgesia. All patients were adequately ventilated. One episode of bradycardia was controlled with atropine. In the immediate postoperative period, no patient presented laryngeal complications and only 1 patient reported significant pain (8 on a visual analog scale). The ProSeal mask was a good choice for use with combined regional-general anesthesia, ensuring control of the airway without causing complications. Analgesia was adequate in most cases.

Comparison of intubating laryngeal mask airway and Bullard laryngoscope for oro-tracheal intubation in adult patients with simulated limitation of cervical movements

BACKGROUND

Intubation of a patient with limited cervical spine movement or in whom movement of the cervical spine is not desirable is always a challenge even to the most experienced anaesthesiologist. The intubating laryngeal mask airway (ILMA) and the Bullard laryngoscope (BL) are two instruments recommended for endotracheal intubation of such patients. We compared their utility and safety in patients with simulated cervical spine immobility using manual inline stabilization (MILS).

METHODS

Sixty-two patients, ASA I or II, between 18 and 65 yr, were enrolled in this prospective and randomized study. They were randomly allocated to one of the two groups: Group BL (Bullard laryngoscope) and Group IL (Intubating Laryngeal Mask Airway). The patients were intubated orally using either equipment after induction of general anaesthesia.

RESULTS

The success rate for intubation in the first or second attempt was higher in Group BL [90.32% (28/31)] than in Group IL [74.2% (23/31)] but was not statistically significant. The number of attempts taken for intubation and the total time to intubate were similar between the groups. Trauma as evidenced by blood on endotracheal tube or sore throat was similar in both groups.

CONCLUSIONS

Both the BL and the ILMA are useful equipment in intubating patients with limitation of cervical movements. Although not statistically significant, the BL may provide a higher success rate of intubation when compared with the ILMA.

Cricoid pressure prevents placement of the laryngeal tube and laryngeal tube-suction II

BACKGROUND

The laryngeal tube has a potential role in patients with a difficult airway, but cricoid pressure is required if the patient is at risk of aspiration. The effect of cricoid pressure on insertion of these devices is unknown.

METHODS

In a randomized cross-over study, the laryngeal tube (25 patients) or the laryngeal tube-suction II (15 patients) was inserted with cricoid pressure applied on one occasion and with sham pressure on the other occasion. Adequacy of ventilation, time to achieve adequate ventilation, and the leak pressure were assessed.

RESULTS

Ventilation was adequate in all patients when sham pressure was applied. Cricoid pressure significantly reduced the rate of adequate ventilation to 6 of 25 patients for the laryngeal tube [P < 0.001; 95% confidence interval (CI) for difference: 59-93%] and to 5 of 15 patients for the laryngeal tube-suction II (P < 0.05; 95% CI for difference: 43-91%). The median time taken to achieve adequate ventilation for the laryngeal tube was 10 s [inter-quartile range (IQR): 8-15] (range 5-26) for sham pressure and 25 s (15-32) (15-33) for cricoid pressure; the median leak pressure was 30 (IQR: 30-30) (range 20-30) cm H2O for sham pressure and 15.5 (14.3-20.5) (12-22) cm H2O for cricoid pressure.

CONCLUSIONS

Continuous cricoid pressure prevents correct placement of the laryngeal tube and the laryngeal tube-suction II such that placement and ventilation via these devices are ineffective. The effect of cricoid pressure on ventilation via these devices, after correct placement, remains unknown.

Oral clonidine premedication reduces minimum alveolar concentration of sevoflurane for laryngeal mask airway insertion in children

BACKGROUND

Sevoflurane is widely employed for inhalational induction in children. Clonidine deepens volatile anesthetics and reduces several types of MAC of sevoflurane. Laryngeal mask airway is a useful device for pediatric anesthesia. The aim of the current study was to determine whether oral clonidine premedication can reduce MAC of sevoflurane for an LMA insertion in children.

METHODS

Fifty-six ASA physical status I patients (3-11 years) scheduled for general anesthesia were randomly divided into two groups of 28 patients each. One group (clonidine group) received clonidine 4 microg x kg(-1) approximately 100 min before anesthesia, and the other (control) group did not. Anesthesia was induced with sevoflurane. Each concentration of sevoflurane, at which an LMA insertion was attempted, was predetermined according to the modification of Dixon's up-and-down method with 0.25% as a step size and held constant for at least 20 min before the trial. All responses ('movement' or 'no movement') to an LMA insertion were assessed.

RESULTS

Minimum alveolar concentration values of sevoflurane for an LMA insertion were lower in the clonidine group (1.31% +/- 0.18% [mean +/- sd]) than in the control group (2.00% +/- 0.16%). Logistic regression analysis revealed that sevoflurane EC95 values were 1.79% and 2.49% in the clonidine and control groups, respectively.

CONCLUSIONS

Oral clonidine premedication reduced the MAC (EC50) and EC95 values of sevoflurane for LMA insertion by 38% and 28%, respectively.

Laryngeal mask airway insertion requires less propofol than endotracheal intubation in dogs

OBJECTIVE

To compare the doses of propofol required for insertion of the laryngeal mask airway (LMA) with those for endotracheal intubation in sedated dogs.

STUDY DESIGN

Randomized prospective clinical study. Animals Sixty healthy dogs aged 0.33-8.5 (3.0 +/- 2.3, mean +/- SD) years, weighing 2.2-59.0 (23.4 +/- 13.6, mean +/- SD) kg, presented for elective surgery requiring inhalation anaesthesia.

METHODS

Animals were randomly assigned to receive either a LMA or an endotracheal tube. Pre-anaesthetic medication was intravenous (IV) glycopyrrolate (0.01 mg kg(-1)) medetomidine (10 microg kg(-1)) and butorphanol (0.2 mg kg(-1)). Repeated IV propofol injections (1 mg kg(-1) in 30 seconds) were given until LMA insertion or endotracheal intubation was achieved, when the presence or absence of laryngospasm, the respiratory rate (fr) and the total dose of propofol used were recorded.

RESULTS

The total propofol dose (mean +/- SD) required for LMA insertion (0.53 +/- 0.51 mg kg(-1)) was significantly lower than for endotracheal intubation (1.43 +/- 0.57 mg kg(-1)). The LMA could be inserted without propofol in 47% of dogs; the remainder needed a single 1 mg kg(-1) bolus (n = 30). Endotracheal intubation was possible without propofol in 3.3% of the dogs, 47% needed one bolus and 50% required two injections (n = 30). The f(r) (mean +/- SD) was 18 +/- 6 and 15 +/- 7 minute(-1) after LMA insertion and intubation, respectively.

CONCLUSION AND CLINICAL RELEVANCE

Laryngeal mask airway insertion requires less propofol than endotracheal intubation in sedated dogs therefore propofol-induced cardiorespiratory depression is likely to be less severe. The LMA is well tolerated and offers a less invasive means of securing the upper airway.

„Schlaf-Wach-Schlaf“-Technik zur CS Wachkraniotomie

Awake craniotomy in tumor and epilepsy surgery or for the implantation of electrodes for deep brain stimulation requires specific anesthesiological strategies. Propofol allows for quick emergence and has little effect on the respiratory function of the usually spontaneously breathing patient. Pain control may be instituted by hemiscalp block for trepanation or local infiltration for deep brain electrode implantation. In addition, low dose remifentanil is recommended for trepanation (i.e. tumor or epilepsy surgery). The airway may be secured by an ordinary Magill tube placed transnasally with its tip underneath the epiglottis. To protect the patient against vomiting an adequate antiemetic prophylaxis is required.

An Evaluation of the Insertion and Function of a New Supraglottic Airway Device, the King LT ™, During Spontaneous Ventilation

Trials of the King LT trade mark (LT, King Systems, Noblesville, IN) in controlled ventilation of the lungs have shown that it is an effective supraglottic airway device. We designed this study to evaluate the King LT regarding ease of insertion, position within the airway, and anatomic sealing properties during spontaneous ventilation in 50 ASA physical status I-III, Mallampati I-III, adult patients undergoing routine general anesthesia. Anesthesia was induced with up to 2 microg/kg fentanyl and 1.5-2 mg/kg propofol and maintained with 70% N2O/30%O2 and isoflurane. Insertion time, oropharyngeal leak pressures, fiberoptic position, and spirometry and hemodynamic data were recorded. Any complications were noted. Insertion was determined to be easy and a patent airway was achieved in all patients. First, second, and third attempt insertion rates were 86%, 12%, and 2%, respectively. Time to place the King LT trade mark was <5 s in 90% of cases. Baseline leak pressures were 31 +/- 8.8 cm H2O (17-50 cm H2O). Complications included laryngospasm (1) and coughing (3) on extubation. The incidence of sore throat at 1 h and 24 h postoperatively was 22% and 15%, respectively. The King LT trade mark is a simple and reliable supraglottic airway device for airway management during spontaneous ventilation.

The laryngeal tube

The laryngeal tube (VBM Medizintechnik, Sulz, Germany) is a relatively new extraglottic airway, designed to secure a patent airway during either spontaneous breathing or controlled ventilation. In this review article, we have assessed the potential role of the laryngeal tube during anaesthesia and during cardiopulmonary resuscitation. There are four variations of the laryngeal tube: standard laryngeal tube, disposable laryngeal tube, laryngeal tube-Suction II and disposable laryngeal tube-Suction II. The design of the device has been revised several times. Insertion of the standard laryngeal tube is as easy as with the laryngeal mask airway classic. The laryngeal tube may provide a better sealing effect than the laryngeal mask. The incidence of complications with the two devices is similar, although the laryngeal tube may require more re-adjustments of its position to obtain a clear airway. Compared with the ProSeal laryngeal mask, the laryngeal tube may be less effective. The efficacy of the standard laryngeal tube is unclear, particularly in patients breathing spontaneously or in children. The efficacy of the laryngeal tube Suction-II and disposable devices is also not clear. From the limited number of studies and reports available, it can be concluded that the laryngeal tube is potentially useful in maintaining a clear airway during anaesthesia and cardiopulmonary resuscitation. In addition, the device may be useful as an aid to tracheal intubation.