Lower cuff pressures improve the seal of pediatric laryngeal mask airways

Effect of different lung recruitment strategies and airway device on oscillatory mechanics in children under general anaesthesia

BACKGROUND

Atelectasis has been reported in 68 to 100% of children undergoing general anaesthesia, a phenomenon that persists into the recovery period. Children receiving recruitment manoeuvres have less atelectasis and fewer episodes of oxygen desaturation during emergence. The optimal type of recruitment manoeuvre is unclear and may be influenced by the airway device chosen.

OBJECTIVE

We aimed to investigate the different effects on lung mechanics as assessed by the forced oscillation technique (FOT) utilising different recruitment strategies: repeated inflations vs. one sustained inflation and different airway devices, a supraglottic airway device vs. a cuffed tracheal tube.

DESIGN

Pragmatic enrolment with randomisation to the recruitment strategy.

SETTING

We conducted this single-centre trial between February 2020 and March 2022.

PARTICIPANTS

Seventy healthy patients (53 boys) aged between 2 and 16 years undergoing general anaesthesia were included.

INTERVENTIONS

Forced oscillations (5 Hz) were superimposed on the ventilator waveform using a customised system connected to the anaesthesia machine. Pressure and flow were measured at the inlet of the airway device and used to compute respiratory system resistance and reactance. Measurements were taken before and after recruitment, and again at the end of surgery.

MAIN OUTCOME MEASURES

The primary endpoint measured is the change in respiratory reactance.

RESULTS

Statistical analysis (linear model with recruitment strategy and airway device as factors) did not show any significant difference in resistance and reactance between before and after recruitment. Baseline reactance was the strongest predictor for a change in reactance after recruitment: prerecruitment Xrs decreased by mean (standard error) of 0.25 (0.068) cmH 2 O s l -1 per  1 cmH 2 O -1  s l -1 increase in baseline Xrs ( P  < 0.001). After correcting for baseline reactance, the change in reactance after recruitment was significantly lower for sustained inflation compared with repeated inflation by mean (standard error) 0.25 (0.101) cmH 2 O ( P  = 0.0166).

CONCLUSION

Although there was no significant difference between airway devices, this study demonstrated more effective recruitment via repeated inflations than sustained inflation in anaesthetised children.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry: ACTRN12619001434189.

Efficacy and safety of three inflation methods of the laryngeal mask airway Ambu® Auraonce™: a randomized controlled study

The laryngeal mask airway (LMA) is commonly used for airway management. Cuff hyperinflation has been associated with complications, poor ventilation and increased risk of gastric insufflation. This study was designed to determine the best cuff inflation method of AuraOnce™ LMA during bronchoscopy and EBUS (Endobronquial Ultrasound Bronchoscopy) procedure. We designed a Randomized controlled, doble-blind, clinical trial to compare the efficacy and safety of three cuff inflation methods of AuraOnce™ LMA. 210 consenting patients scheduled for EBUS procedure under general anesthesia, using AuraOnce™ LMA were randomized into three groups depending on cuff insufflation: residual volume (RV), half of the maximum volume (MV), unchanged volume (NV). Parameters regarding intracuff pressure (IP), airway leak pressure (OLP), leakage volume (LV) were assessed, as well as postoperative complications (PC). 201 (95.7%) patients completed the study. Mean IP differed between groups (MV: 59.4 ± 32.4 cm H2O; RV: 75.1 ± 21.1 cm H2O; NV: 83.1 ± 25.5 cmH20; P < 0.01). The incidence of IP > 60 cmH2O was lower in the MV group compared to the other two (MV: 20/65(30.8%); RV:47/69 (68.1%); NV 48/67 (71.6%); p < 0.01). The insertion success rate was 89,6% (180/201) at first attempt, with no difference between groups (p = 0.38). No difference between groups was found either for OLP (p = 0.53), LV (p = 0.26) and PC (p = 0.16). When a cuff manometer is not available, a partial inflation of AuraOnce™ LMA cuff using MV method allows to control intracuff pressure, with no significant changes of OLP and LV compared to RV and NV insufflation method.Registration clinical trial: NCT04769791.

Sealing mechanism study of laryngeal mask airways via 3D modelling and finite element analysis

Proper sealing of laryngeal mask airways (LMAs) is critical for airway management in clinical use. Understanding the sealing mechanism can significantly help front-line anaesthetists to reduce the incidence of adverse events. However, anaesthetists, who may not have the most substantial engineering backgrounds, lack intuitive ways to develop an understanding of the LMA sealing mechanism effectively. The paper aims to study the LMA-pharynx sealing mechanisms from the perspective of front-line anaesthetists. We use a computer-aided 3D modelling technique to visualise the LMA—pharynx interactions, which helps anaesthetists identify the critical areas of complications. Furthermore, we conduct a quantitative pressure distribution analysis of the LMA-pharynx contacting surface using the finite element analysis technique, which helps further understand the sealing mechanics in those areas. We present two cases studies based on one male volunteer, aged 50, inserted with a ProSeal LMA. In the first case, a relatively low cuff pressure (CP) was applied to simulate the clinical circumstances in which complications related to air leakage are most likely to happen; in the second case, we increase the CP to a relatively high value to simulate the scenarios with an increased risk of complications related to high mucosal pressure. The experiments suggest the follows: (1) Sore throat complications related to high mucosal pressure is most likely to occur in the hypopharynx with a high CP setting, particularly in the areas where the cricoid cartilage presses the mucosa. (2) The narrow hyoid bone super horn width likely causes LMA insertion difficulties. (3) Insufficient CP will significantly increase the risk of air leakage in the oropharynx. A complete sealing pressure line in the contacting surface will be formed with sufficient CP, thereby preventing the air leakage into the oral.

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.

Effects of Peak Inspiratory Pressure-Guided Setting of Intracuff Pressure for Laryngeal Mask Airway Supreme™ Use during Laparoscopic Cholecystectomy: A Randomized Controlled Trial

PURPOSE

To determine the effects of peak inspiratory pressure (PIP)-guided intracuff pressure (ICP) modulation of laryngeal mask airway (LMA) Supreme™ during laparoscopic cholecystectomy.

METHODS

Totally 120 patients were randomly divided using computer-generated numbers into a control group (n = 60; ICP, 60 cmH₂O) and a PIP group (n = 60), in which ICP was increased with 5 cmH₂O each time from PIP level until no air leaks from the oropharynx. PIP, ICP, cuff volume (CV), oropharyngeal leak pressure (OLP) and leak fraction (LF) were recorded before and after pneumoperitoneum establishment. Postoperative pharyngolaryngeal complications (sore throat, dysphagia, pharyngeal hematoma, and dysphonia) were also recorded.

RESULTS

Demographic data were similar in the two groups. The CV and ICP before and after pneumoperitoneum were significantly lower in the PIP group (CV: 15.6 ± 2.3 mL and 21.0 ± 2.6 mL; ICP: 14.3 ± 2.9 cmH₂O and 20.5 ± 3.4 cmH₂O) than in the control group (CV: 33.0 ± 2.8 mL and 32.8 ± 1.9 mL; ICP: 60.0 ± 0.1 cmH₂O and 60.0 ± 0.1 cmH₂O) (P < 0.05). Although OLP was lower in the PIP group (P < 0.05), the LF was similar in the two groups (P > 0.05). There were fewer postoperative pharyngolaryngeal complications in the PIP group (P < 0.05).

CONCLUSIONS

Compared with a fixed ICP of 60 cmH₂O, PIP-guided ICP modulation during LMA Supreme™ use provided effective airway sealing at a lower CV and ICP, and produced fewer postoperative pharyngolaryngeal complications in patients undergoing laparoscopic cholecystectomy.

Airway devices in paediatric anaesthesia

Airway devices were first used in children since 1940 and thereafter an increasingly large number of paediatric airway devices have come into our armamentarium. To control and protect the airway in children during anaesthesia, in intensive care unit or in emergency department either tracheal intubation is performed under direct or indirect visualization of vocal cords with the help of laryngoscopes or video-laryngoscopes respectively or it can be done blindly or by using special instruments such as fiberoptic laryngoscope, lighted stylet or Bullard laryngoscope to name a few. Airway also can be maintained with the help of Laryngeal mask airways, oropharyngeal and nasopharyngeal airways. Updating our information and knowledge regarding these developments is pivotal to our practice of paediatric anaesthesia. With a thorough search of books, MEDLINE, MEDNET, clinical trials.gov.in, this article aims at focusing and understanding a brief basis of paediatric devices and their use.

Comparison of laryngeal mask airway supremeTM as non-inflatable cuff device and self-pressurized air-QTM in children: Randomized controlled non-inferiority study

BACKGROUND

Supraglottic airway (SGA) device with non-inflatable cuff reduce the airway complications associated with cuff hyperinflation. The aim of the study is to determine whether the default setting of Supreme is as effective as the non-inflatable cuff devices. The oropharyngeal leak pressure was measured and compared between the Supreme and Air-Q, a typical non-inflatable cuff device. We hypothesized that the default setting of Supreme is non-inferior to the the Air-Q self-pressurized (SP) in respect to the oropharyngeal leak pressure.

METHODS

Eighty-four patients aged 1 to 7 years who were scheduled for general anesthesia, participated in the study. The patients were randomly assigned to Supreme group (n = 41) or Air-Q SP group (n = 43). We considered that the primary outcome, oropharyngeal leak pressure of Supreme group would be non-inferior to the Air-Q SP group, within 3 cmH2O. Other outcomes included tidal volume loss, difficulty of insertion, insertion time, and complications.

RESULTS

The oropharyngeal leak pressure of the Supreme and Air-Q SP was 19.9 ± 4.1 cm H2O and 17.4 ± 2.9 cm H2O, respectively. The mean differences of 2 devices (Air-Q SP-Supreme) were -2.5 cm H2O, (95% confidence interval [-4.0 to -0.9], P = .002). The upper CI was smaller than the non-inferiorty margin (3 cm H2O). This result suggested that the default setting of Supreme was superior to the Air-Q SP with respect to the oropharyngeal leak pressure. However, there were no significant differences in tidal volume loss over time, ease of device insertion score, insertion time, and complications.

CONCLUSIONS

The Supreme can be used in the default setting in pediatric patients accordingly in terms of tolerable leak pressure and the stability for mechanical ventilation compared with Air-Q SP.

Management of the child's airway under anaesthesia: The French guidelines

OBJECTIVE

To provide French guidelines about "Airway management during paediatric anaesthesia".

DESIGN

A consensus committee of 17 experts from the French Society of Anaesthesia and Intensive Care Medicine (Société Française d'Anesthésie-Réanimation, SFAR) and the Association of French speaking paediatric anaesthesiologists and intensivists (Association Des Anesthésistes Réanimateurs Pédiatriques d'Expression Francophone, ADARPEF) was convened. The entire process was conducted independently of any industry funding. The authors followed the principles of the Grading of Recommendations Assessment, Development and Evaluation (GRADE®) system to assess the quality of evidence. The potential drawbacks of making strong recommendations in the presence of low-quality evidence were emphasised. Few recommendations were not graded.

METHODS

The panel focused on 7 questions: 1) Supraglottic Airway devices 2) Cuffed endotracheal tubes 3) Videolaryngoscopes 4) Neuromuscular blocking agents 5) Rapid sequence induction 6) Airway device removal 7) Airway management in the child with recent or ongoing upper respiratory tract infection. Population, intervention, comparison, and outcomes (PICO) questions were reviewed and updated as needed, and evidence profiles were generated. The analysis of the literature and the redaction of the recommendations were then conducted according to the GRADE® methodology.

RESULTS

The SFAR Guideline panel provides 17 statements on "airway management during paediatric anaesthesia". After two rounds of discussion and various amendments, a strong agreement was reached for 100% of the recommendations. Of these recommendations, 6 have a high level of evidence (Grade 1 ± ), 6 have a low level of evidence (Grade 2 ± ) and 5 are experts' opinions. No recommendation could be provided for 3 questions.

CONCLUSIONS

Substantial agreement exists among experts regarding many strong recommendations for paediatric airway management.

Current practice patterns of supraglottic airway device usage in paediatric patients amongst anaesthesiologists: A nationwide survey

Background and Aims:

Supraglottic airway devices (SGADs) are increasingly being used for airway management in paediatric patients undergoing general anaesthesia. This survey was designed to assess the nationwide practice patterns of SGAD usage in paediatric patients.

Methods:

A questionnaire of 28 questions was circulated amongst 16,532 members of the Indian Society of Anaesthesiologists through online survey engine Google Forms^® and served manually to 500 delegates attending the Asian Society of Paediatric Anaesthesiologists conference 2017. Percentage, mean and standard deviation were calculated using Microsoft Excel 2016 (Redmond, WA, USA).

Results:

Four hundred and five (2.3%) valid responses were obtained. The most commonly used device was i-gel^© (60.74%). Three hundred and four (75.06%) respondents had access to second-generation SGADs. Second-generation devices (60.74%) were more commonly used than first-generation devices (39.26%). Anaesthesiologists utilised SGADs in various challenging scenarios such as in the difficult airway (53.33%), remote locations (55.47%), ophthalmologic (38.77%) and long-duration surgeries (17.53%). Sixty per cent respondents did not use SGADs in laparoscopic surgery. Disposable SGADs were reused by 77.28% respondents. Oropharyngeal seal and intracuff pressures were not measured by 86.91% and 56.92% respondents, respectively. Difficulty in size selection (84.19%), securing position (82.22%) and maintaining unobstructed ventilation (78.76%) were common problems encountered while using SGADs.

Conclusion:

Although there is a widespread use of second-generation SGADs in Indian paediatric anaesthesia, safe practices such as using capnography, measurement of oropharyngeal seal pressure, cuff pressure and appropriate disinfection are lacking.

A comparison of i-gel™ and Laryngeal Mask Airway Supreme™ during general anesthesia in infants

Background

The i-gel™ (i-gel) and Laryngeal Mask Airway Supreme™ (LMA Supreme) have been safely used in children. We compared the airway performance of the i-gel and LMA Supreme in infants undergoing general anesthesia.

Methods

Sixty infants with American Society of Anesthesiologists physical status I or II were randomly assigned to place either the i-gel or the LMA Supreme. The size 1 or 1.5 of each airway was selected by the weight of infants. The primary outcome variable was oropharyngeal leak pressure (OLP). We also assessed insertion success rate, insertion time, fiberoptic view of the larynx, airway quality, airway manipulations, and perioperative complications.

Results

Demographic data did not differ between the two groups. Insertion success rate was similar in both groups. OLP for the i-gel (26.0 ± 3.8 cmH₂O) was higher than for the LMA Supreme (23.7 ± 3.2 cmH₂O) (P = 0.016). Insertion time for the i-gel (16.4 ± 2.8 s) was shorter than for the LMA Supreme (18.5 ± 2.7 s) (P = 0.002). There were no differences in fiberoptic view of the larynx, airway quality, airway manipulations, and complications between the two groups.

Conclusions

This study demonstrated that the i-gel and LMA Supreme provided a similar performance of airway in infants. Compared with the LMA Supreme, the i-gel provided shorter insertion time and higher OLP in infants.

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.

A Survey of Current Practice of Supraglottic Airway Devices in Pediatric Anesthesia from India

Background and Objectives:

Supraglottic airway devices (SADs) have revolutionized the pediatric anesthetic practice and got a key role in difficult airway (DA) management. Several modifications of SADs design had come up to improve their safety.

Aim:

The aim of this survey was to determine the current usage of SADs in pediatric anesthetic practice, their availability, and to know any difficulties noted in practice.

Methods:

It was a questionnaire survey among the anesthesiologists who attended the National Pediatric Anesthesia Conference-2016. The questionnaire assessed the current practice preferences of SADs in routine pediatric cases and DA management, availability of various devices, and any difficulties noted in their usage.

Results:

First-generation SADs were widely available (97%), and 64% of respondents preferred to use it for pediatric short cases. 64% felt the use of SADs free their hands from holding the facemask and 58% found better airway maintenance with it. Intraoperative displacement (55%) was the common problem reported and only 11% felt aspiration as a problem. Most of the respondents (73%) accepted its use as rescue device in airway emergency, and 84% felt the need of further randomized controlled studies on safety of SADs in children. The majority were not confident to use SADs in neonates.

Interpretation and Conclusions:

The key role of SADs in DA management was well accepted, and aspiration was not a major problem with the use of SADs. Although many newer versions of SADs are available, classic laryngeal mask remains the preferred SAD for the current practitioner. Further, RCTs to ensure the safety of SADs in children are warranted.

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.

Overinflation of the cuff and pressure on the neck reduce the preventive effect of supraglottic airways on pulmonary aspiration: an experimental study in human cadavers

BACKGROUND

The oesophageal leak pressure is defined as the pressure which breaks the seal between the cuff of a supraglottic airway and the peri-cuff mucosa, allowing penetration of fluid into the pharynx and the oral cavity. As a consequence, a decrease in this variable increases the risk of reflux and can lead to pulmonary aspiration. The aim of this study was to analyse the effects of cuff overinflation and pressure on the neck on the oesophageal leak pressure of seven supraglottic airways.

METHODS

Three laryngeal masks, two laryngeal tubes, and two oesophageal-tracheal tubes were tested in an experimental setting. In five human cadavers, we simulated a sudden increase in oesophageal pressure. To measure baseline values (control), we used an intracuff pressure as recommended by the manufacturer. The first intervention included overinflation of the cuff by applying twice the amount of pressure recommended. A second intervention was defined as external pressure on the neck.

RESULTS

The oesophageal leak pressure was decreased for laryngeal masks (control, 28 cm H2O; overinflation, 9 cm H2O; pressure on the neck, 8 cm H2O; P<0.01) and for laryngeal tubes (control, 68 cm H2O; overinflation, 37 cm H2O; pressure on the neck, 39 cm H2O; P<0.01) and was unaffected for oesophageal-tracheal tubes (control, 126 cm H2O; overinflation/pressure on the neck, 130 cm H2O; n.s.).

CONCLUSION

Cuff overinflation and pressure on the neck can enhance the risk of gastro-oesophageal reflux when using supraglottic airways. Therefore, both manoeuvres should be avoided in clinical practice.

[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.

Small is the new big: An overview of newer supraglottic airways for children

Almost all supraglottic airways (SGAs) are now available in pediatric sizes. The availability of these smaller sizes, especially in the last five years has brought a marked change in the whole approach to airway management in children. SGAs are now used for laparoscopic surgeries, head and neck surgeries, remote anesthesia; and for ventilation during resuscitation. A large number of reports have described the use of SGAs in difficult airway situations, either as a primary or a rescue airway. Despite this expanded usage, there remains little evidence to support its usage in prolonged surgeries and in the intensive care unit. This article presents an overview of the current options available, suitability of one over the other and reviews the published data relating to each device. In this review, the author also addresses some of the general concerns regarding the use of SGAs and explores newer roles of their use in children.

[Impact of the practising anesthesiologist team member on the laryngeal mask cuff pressures and adverse event rate]

OBJECTIVE

We have planned to evaluate the laryngeal mask cuff pressures (LMcp) inflated by anesthesia workers of several seniority, without using manometer.

METHODS

180 patients scheduled to have short duration surgery with laryngeal mask were included in the study. Five anesthesia specialists (Group S), 10 residents (Group R) and 6 technicians (Group T) inflated the LMc; thereafter LMcp were measured with pressure manometer. Participants have repeated this practice in at least five different cases. LMcp higher than 60cm H2O at the initial placement or intraoperative period were adjusted to normal range. Sore throat was questioned postoperatively. Groups were compared in terms of mean LMcp and occupational experience.

RESULTS

At the settlement of LM, LMcp pressures within the normal range were determined in 26 (14.4%) cases. Mean LMcp after LM placement in Group S, R and T were 101.2±14.0, 104.3±20.5cm H2O and 105.2±18.4cm H2O respectively (p>0.05). Mean LMcp values in all measurement time periods within the groups were above the normal limit (60cm H2O). When groups were compared in terms of LMcp, no difference has been found among pressure values. Occupational experience was 14.2±3.9; 3.3±1.1 and 6.6±3.8 years for specialists, residents and technicians respectively and measured pressure values were not different in regard of occupational experience. Seven (3.9%) patients had sore throat at the 24th hour interview.

CONCLUSION

Considering lower possibility of normal adjustment of LMcp and ineffectiveness of occupational experience to obtain normal pressure values, it is suitable that all anesthesia practitioners should adjust LMcp with manometer.

Impact of the practising anesthesiologist team member on the laryngeal mask cuff pressures and adverse event rate

OBJECTIVE

We have planned to evaluate the laryngeal mask cuff pressures (LMcp) inflated by anesthesia workers of several seniority, without using manometer.

METHODS

180 patients scheduled to have short duration surgery with laryngeal mask were included in the study. Five anesthesia specialists (Group S), 10 residents (Group R) and 6 technicians (Group T) inflated the LMc; thereafter LMcp were measured with pressure manometer. Participants have repeated this practice in at least five different cases. LMcp higher than 60 cm H2O at the initial placement or intraoperative period were adjusted to normal range. Sore throat was questioned postoperatively. Groups were compared in terms of mean LMcp and occupational experience.

RESULTS

At the settlement of LM, LMcp pressures within the normal range were determined in 26 (14.4%) cases. Mean LMcp after LM placement in Group S, R and T were 101.2 ± 14.0, 104.3 ± 20.5 cm H2O and 105.2 ± 18.4 cm H2O respectively (p > 0.05). Mean LMcp values in all measurement time periods within the groups were above the normal limit (60 cm H2O). When groups were compared in terms of LMcp, no difference has been found among pressure values. Occupational experience was 14.2 ± 3.9; 3.3 ± 1.1 and 6.6 ± 3.8 years for specialists, residents and technicians respectively and measured pressure values were not different in regard of occupational experience. Seven (3.9%) patients had sore throat at the 24th hour interview.

CONCLUSION

Considering lower possibility of normal adjustment of LMcp and ineffectiveness of occupational experience to obtain normal pressure values, it is suitable that all anesthesia practitioners should adjust LMcp with manometer.

An update on newer pediatric supraglottic airways with recommendations for clinical use

Supraglottic airways are an established part of routine and emergency pediatric airway management, including use in difficult airways and neonatal resuscitation. With the introduction of newer supraglottic airways in children, efficacy can only be determined by comparing these devices with those that are already well established (laryngeal mask airway Classic and laryngeal mask airway ProSeal). This narrative review aims to present the current literature on these newer supraglottic airways and give recommendations for their use in various clinical scenarios based on the existing evidence.

A randomized comparison of the i-gel with the self-pressurized air-Q intubating laryngeal airway in children

BACKGROUND

Supraglottic airway devices with noninflatable cuff have advantages in omitting the cuff pressure monitoring and reducing potential pharyngolaryngeal complications. Typical devices without cuff inflation available in children are the i-gel and the self-pressurized air-Q intubating laryngeal airway (air-Q SP). To date, there is no comparative study between these devices in pediatric patients.

AIM

The purpose of this randomized study was to compare the i-gel(™) and the self-pressurized air-Q(™) intubating laryngeal airway (air-Q SP) in children undergoing general anesthesia.

METHODS

Eighty children, 1-108 months of age, 7-30 kg of weight, and scheduled for elective surgery in which supraglottic airway devices would be suitable for airway management, were randomly assigned to either the i-gel or the air-Q SP. Oropharyngeal leak pressure and fiberoptic view were assessed three times as follows: after insertion and fixation of the device, 10 min after initial assessment, and after completion of surgery. We also assessed insertion parameters and complications.

RESULTS

Insertion of the i-gel was regarded as significantly easier compared to the air-Q SP (P = 0.04). Compared to the air-Q SP group, the i-gel group had significantly higher oropharyngeal leak pressures at all measurement points and significantly lower frequencies of gastric insufflation at 10 min after initial assessment and completion of surgery. The air-Q SP group had better fiberoptic views than the i-gel group at all measurement points.

CONCLUSION

Our results showed that the i-gel had easier insertion and better sealing function, and the air-Q SP provided improved fiberoptic views in children requiring general anesthesia.

The randomized crossover comparison of airway sealing with the laryngeal mask airway Supreme(™) at three different intracuff pressures in children

BACKGROUND

An intracuff pressure of 80 cm H2 O in the adult-sized laryngeal mask airway Supreme has been recommended to obtain a higher oropharyngeal leak pressure (OLP). However, the intracuff pressure for the higher OLP in the pediatric laryngeal mask airway Supreme could be different from that in the adult-sized laryngeal mask airway Supreme. Thus, we measured and compared OLP at three intracuff pressures of 40, 60, and 80 cm H2 O in the pediatric laryngeal mask airway Supreme.

METHODS

This study was designed as a randomized crossover study and enrolled 36 children, aged 0-108 months and 5-30 kg in weight. After insertion of the laryngeal mask airway Supreme, oropharyngeal leak pressure (OLP) was measured at intracuff pressures of 40, 60, and 80 cm H2 O according to one of six sequences produced on the basis of 3 × 6 Williams crossover design. During the intraoperative period, the laryngeal mask airway Supreme was maintained using the last intracuff pressure of the allocated sequence. The intraoperative and postoperative complications were compared among three maintenance intracuff pressures.

RESULTS

OLP at the intracuff pressure of 60 cm H2 O was significantly higher than that of 40 cm H2 O (17.9 ± 3.9 vs 16.9 ± 4.2 cm H2 O, P = 0.004) and was comparable with that of 80 cm H2 O (17.9 ± 3.9 vs 17.8 ± 4.6 cm H2 O, P = 0.938). There were no significant differences of intraoperative and postoperative complications among the three maintenance intracuff pressures.

CONCLUSION

Our results suggest that the use of an intracuff pressure of 60 cm H2 O in pediatric laryngeal mask airway Supreme provides a higher OLP compared with 40 cm H2 O.

Baby cuff as a reason for laryngeal mask airway cuff malfunction during airway management for anesthesia

Placement of laryngeal mask airway (LMA) is a blind procedure without requiring laryngoscopy. The reported success rate for LMA insertion at the first attempt is almost 95%; however, many functioning LMAs may not be in an ideal anatomic place. It seems that disposable LMAs have more stable cuff pressure compared to reusable LMAs; therefore, Anesthesiologists should bear in mind this fact when using reusable LMAs to achieve a proper sealing and safe airway management. In this report, we introduced a case with malfunction of LMA cuff during the airway management.

A novel modified laryngeal mask airway allowing full separation of the digestive and respiratory tracts, along with double-catheter ventilation, diagnosis, and treatment

The aim of this study was to design a novel, modified, multifunctional, and safe laryngeal mask airway (LMA). We designed an LMA with an internal catheter extending beyond the tip of the cuff. The protruding end of the internal catheter was provided with a catheter cuff, the space between the internal and external catheters was ventilatory, and the inlet ends of the 2 catheters were provided with standard connectors. We found that this design prevented reflux or aspiration of gastric content into the airway, prevented LMA dislocation, allowed ventilation through both the internal and external catheters, and allowed endoscopic examination and treatment of the gastrointestinal and respiratory tracts through both the internal and external catheters. This design overcomes the drawbacks and extends the functions of previous LMAs, offering a new approach to the development of LMAs.

Cuff filling volumes for pediatric classic laryngeal mask airways: comparison of clinical end points versus adjusted cuff pressure

BACKGROUND

Clinical end points are often used to guide inflation and adequacy of cuff seal after laryngeal mask airway placement. However, clinical end points for cuff inflation have been shown to have significantly higher intracuff pressure. The adjusted cuff pressure between 55 and 60 cm H(2)O causes significantly better seal of laryngeal mask airway. We prospectively assessed the cuff pressures generated by cuff inflation guided by clinical end points, and the actual volume of air required to achieve cuff pressures between 55 and 60 cm H(2)O for sizes 1-2.5 reusable classic laryngeal mask airway.

METHODS

Two hundred and three ASA I and II children undergoing elective cataract surgery requiring general anesthesia receiving laryngeal mask airway sizes 1-2.5 were recruited to this study. The laryngeal mask airway was placed using standard technique. After insertion of laryngeal mask airway, the cuff was slowly inflated until a slight outward shift of device was noted. Cuff pressures were measured using calibrated hand held Portex Cuff Inflator Pressure Gauge (Portex Limited, Hythe, Kent, UK). If the cuff pressure was >60 cm H(2)O, the cuff was deflated to achieve a cuff pressure of 55-60 cm H(2)O. The volume of air required to achieve this pressure was recorded.

RESULTS

The volume of air required to achieve the pressure between 55 and 60 cm H(2)O in laryngeal mask airway size 1, 1.5, 2.0, and 2.5 were 2.750 ± 0.2565, 4.951 ± 0.5378, 6.927 ± 0.6328, and 10.208 ± 1.4535 ml, respectively. The difference between the initial and the final cuff volumes and pressures in all laryngeal mask airway sizes were statistically significant(P = 0.000).

CONCLUSION

Lower cuff volumes are required to achieve a pressure of 60 cm H(2)O than those required if clinical end points are used as a sole guide for determining cuff inflation for patients receiving pediatric laryngeal mask airways.

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 normal and the challenging pediatric airway

Management of a child's airway is one of the main sources of stress for anesthetists who do not routinely anesthetize children. Unfortunately, trainees are gaining less experience in pediatric airway management than in the past, which is particularly difficult at a time when some beliefs about airway management are being challenged and airway management is less standardized. Fortunately, most children have an easily managed, normal airway. Nevertheless, it is of vital importance to teach our trainees the basic airway skills that are probably the most important skill in an anesthetists' repertoire when it comes to a difficult airway situation. This review focuses on the airway management in children with a normal and a challenging airway. Different choices of airway management in children, and their advantages and disadvantages are discussed. Furthermore, the three broad causes of a challenging airway in children and infants are highlighted - the difficulty obtaining a mask seal, difficulty visualizing the vocal cords, and the third cause in which the larynx can be visualized but the difficulty lies at or beyond that level. Guidelines are given how to deal with these patients as well as with the feared but rare scenario of 'cannot ventilate, cannot intubate' in children.

A randomised trial comparing the i-gel (TM) with the LMA Classic (TM) in children

We performed a prospective, randomised trial comparing the i-gel(TM) with the LMA Classic(TM) in children undergoing general anaesthesia. Ninety-nine healthy patients were randomly assigned to either the i-gel or the LMA Classic. The outcomes measured were airway leak pressure, ease of insertion, time taken for insertion, fibreoptic examination and complications. Median (IQR [range]) time to successful device placement was shorter with the i-gel (17.0 (13.8-20.0 [10.0-20.0]) s) compared with the LMA Classic (21.0 (17.5-25.0 [15.0-70.0]) s, p = 0.002). There was no significant difference in oropharyngeal leak pressure between the two devices. A good fibreoptic view of the glottis was obtained in 74% of the i-gel group and in 43% of the LMA Classic group (p < 0.001). There were no significant complications. In conclusion, the i-gel provided a similar leak pressure, but a shorter insertion time and improved glottic view compared with the LMA Classic in children.

The effect of head rotation on efficiency of ventilation and cuff pressure using the PLMA in pediatric patients

Background

This study examined whether changing the head position from neutral to side can affect expiratory tidal volume (TV) and cuff pressure when the appropriate sizes of a Proseal™ Laryngeal Mask Airway (PLMA)-depending on the body weight -are used in pediatric patients during pressure controlled ventilation (PCV).

Methods

Seventy-seven children (5-30 kg) were divided into three groups according to their body weight, PLMA#1.5 (group I, n = 24), #2 (group II, n = 26), and #2.5 (group III, n = 27). After anesthesia induction, a PLMA was placed with a cuff-pressure of 60 cmH₂O. The TV and existence of leakage at the peak inspiratory pressure (PIP) of 20 cmH₂O, and the appropriate PIP for TV 10 ml/kg were examined. Upon head rotation to the left side, the TV, PIP, cuff pressure changes, and the appropriate PIP to achieve a TV 10 ml/kg were evaluated.

Results

Head rotation of 45 degrees to the left side during PCV caused a significant increase in cuff pressure and a decrease in TV, and there was no definite leakage. Changes in PIP and TV were similar in the three groups. The cuff pressure increased but there was no significant difference between the three groups.

Conclusions

Although cuff pressure and TV of the PLMA were changed significantly after turning the head from the neutral position to the side, a re-adjustment of the cuff pressure and PIP to maintain a TV of 10 ml/kg can make the placed PLMA useful and successful in pediatric patients under general anesthesia.

Prospective evaluation of the self-pressurized air-Q intubating laryngeal airway in children

OBJECTIVES

To assess the clinical efficacy of the self-pressurized air-Q ILA™ (ILA-SP).

AIM

  The purpose of this prospective audit was to evaluate the feasibility of the ILA-SP in clinical practice and generate data for future comparison trials.

BACKGROUND

The ILA-SP is a new first-generation supraglottic airway for children with a self-adjusting cuff and lack of a pilot balloon.

METHODS

Over a 4-month period, 352 children with an ASA physical status of I-III, newborn to 18 years of age, undergoing various procedures were studied. Data points assessed included insertion success rates, airway leak pressures, quality of ventilation, and perioperative complications associated with the use of this device.

RESULTS

In 349 of the 352 patients in this study, the ILA-SP was used successfully as a primary supraglottic airway device in a variety of patients. Three patients required conversion to a standard laryngeal mask airway or a tracheal tube. The mean initial airway leak pressure for all patients was 17.8 ± 5.4 cm H(2)O, and 20.4 ± 5.5 cm H(2)O when re-checked at 10 min, which was statistically significant (P < 0.001). Complications were limited to 14 patients and related to reflex activation of the airway (coughing, laryngospasm, and bronchospasm) (n = 10), sore throat (n = 3), and blood staining on removal of the device (n = 1). There were no episodes of regurgitation, aspiration, or hoarseness.

CONCLUSIONS

Acceptable clinical performance was demonstrated with the ILA-SP for a variety of procedures in infants and children with spontaneous and positive pressure ventilation. Future studies comparing this device to other supraglottic airways may provide useful information regarding the safety of the ILA-SP in pediatric clinical practice.

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.

Recent advances in airway management in children

Recent anatomic findings, technological progress, and both in vitro and in vivo studies of the pressure generated in the cuff of endotracheal tubes and supraglottic airways should lead to modification of the way we control the pediatric upper airway.

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.

Comparison of different techniques of laryngeal mask placement in children

PURPOSE OF REVIEW

The insertion of laryngeal mask airway is not always easy in children, and many techniques are described to improve success rate of placement. It is very important to determine the optimal insertion technique as unsuccessful prolonged insertion and multiple attempts are associated with adverse respiratory events and trauma in children. This article will review different techniques studied recently for the placement of classical laryngeal mask airway in children as well as recent findings of cuff pressure and depth of anesthesia for laryngeal mask airway placement. Laryngeal mask airway in children has undergone many modifications such as ProSeal laryngeal mask airway to improve its functioning. This article will also review different insertion techniques for ProSeal laryngeal mask airway.

RECENT FINDINGS

Rotational technique with partially inflated cuff is reported to have the highest success rate of insertion and lowest incidence of complications for classical laryngeal mask airway in children. Clinical endpoints for cuff inflation are associated with significant hyperinflation and increased leakage around the laryngeal mask airway cuff. The inferences regarding the dosage of intravenous anesthetic agents and end-tidal concentration of volatile anesthetics in children to achieve adequate depth for laryngeal mask airway placement are very difficult to draw. ProSeal laryngeal mask airway is associated with a very high first attempt success and overall success of insertion in children.

SUMMARY

Rotational technique may be considered as the first technique of choice for classical laryngeal mask airway insertion in children. The routine use of cuff pressure monitoring is mandatory during the use of laryngeal mask airway in children. Modification of laryngeal mask airway in children, that is ProSeal laryngeal mask airway, is promising and improves the success rate of insertion.

Current world literature

This bibliography is compiled by clinicians from the journals listed at the end of this publication. It is based on literature entered into our database between 1 February 2008 and 31 January 2009 (articles are generally added to the database about two and a half months after publication). In addition, the bibliography contains every paper annotated by reviewers; these references were obtained from a variety of bibliographic databases and published between the beginning of the review period and the time of going to press. The bibliography has been grouped into topics that relate to the reviews in this issue.

A critique of elective pediatric supraglottic airway devices

In 1988, when the Laryngeal Mask Airway-Classic (Intavent Orthofix, Maidenhead, UK), was introduced there were only two choices of airway management: tracheal tube or facemask. The supraglottic airway, as we now understand the term, did not exist. Yet, 20 years later, we are faced with an ever increasing choice of supraglottic airway devices (SAD). For many SADs, with the exception of the LMA-Classic and LMA-Proseal (Intavent Orthofix, Maidenhead, UK), there is a lack of high quality data of efficacy. The best evidence requires a randomized controlled trial comparing a new device against an established alternative, properly powered to detect clinically relevant differences in clinically important outcomes. Such studies in children are very rare. Safety data is even harder to establish particularly for rare events such as aspiration. Therefore, most safety data comes from extended use rather than high quality evidence which inevitably biases against newer devices. For reason of these factors, claims of efficacy and particularly safety must be interpreted cautiously. This narrative review aims to present the evidence surrounding the use of currently available pediatric SADs in routine anesthetic practice.

Advanced airway management

PURPOSE OF REVIEW

Advanced airway management in children can be challenging, and the potential for morbidity following failed attempts is high.

RECENT FINDINGS

Supraglottic rescue devices, including the laryngeal mask airway, esophageal-tracheal combination tube, and laryngeal tube have been shown to be suitable ventilation strategies following failed intubation and in arrest scenarios. In addition, a newly developed reversal agent for rocuronium is being investigated as a means of limiting the duration of neuromuscular blockade following rapid sequence induction. Finally, the advent of video laryngoscopy has been shown to have advantages over traditional direct laryngoscopy, in terms of both patient care and training.

SUMMARY

Pediatric providers are encouraged to develop familiarity with emerging rescue ventilation devices, as well as recent advances in the practice of rapid sequence induction and laryngoscopy.

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.