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

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.

Unanticipated difficult airway after prolonged use of a laryngeal mask airway

The laryngeal mask airway (LMA) is recognized as a safe alternative to endotracheal intubation for short-term airway maintenance. In this case report we present the case of a term neonate with upper airway obstruction which was managed with a deflated LMA for 7 consecutive days. Despite previous reports of extended LMA use in neonates without complications, this patient experienced significant pharyngeal mucosal injury and edema, leading to difficulty with subsequent intubation attempts.

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.

Comparison of two different flexible laryngeal airway masks in pediatric ophthalmic surgeries: A retrospective study

This study aimed to compare the clinical effects of the Medis flexible laryngeal mask airway (FLMA) with those of the Ambu AuraFlex FLMA in pediatric ophthalmic surgery. A total of 80 patients, aged 1 to 5 years, in American Society of Anesthesiologists I-II, weighing ≥10 kg, and without any existing airway difficulties, were enrolled in this study. The patients were randomly divided into Group M (Medis FLMA) and Group A (Ambu AuraFlex FLMA). The time of insertion, number of attempts, finger assistance required, manipulation, oropharyngeal leak pressure (OLP), fiberoptic grade of view, and complications such as bloodstaining, hoarseness, and sore throat were recorded. Group M showed a significantly higher OLP than did Group A (P = .002); however, Group M required more finger assistance than did Group A (P = .009). There were no statistically significant differences between the 2 groups in terms of insertion time, number of attempts, manipulation, fiberoptic view grade, or complications. Both the Medis and Ambu AuraFlex FLMA can provide smooth ventilation during pediatric ophthalmic surgeries. The Medis FLMA showed a higher OLP than did the Ambu AuraFlex FLMA but required more finger assistance during insertion.

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.

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.

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

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

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.

Controversies in Pediatric Perioperative Airways

Pediatric airway management is a challenge in routine anesthesia practice. Any airway-related complication due to improper procedure can have catastrophic consequences in pediatric patients. The authors reviewed the current relevant literature using the following data bases: Google Scholar, PubMed, Medline (OVID SP), and Dynamed, and the following keywords: Airway/s, Children, Pediatric, Difficult Airways, and Controversies. From a summary of the data, we identified several controversies: difficult airway prediction, difficult airway management, cuffed versus uncuffed endotracheal tubes for securing pediatric airways, rapid sequence induction (RSI), laryngeal mask versus endotracheal tube, and extubation timing. The data show that pediatric anesthesia practice in perioperative airway management is currently lacking the strong evidence-based medicine (EBM) data that is available for adult subpopulations. A number of procedural steps in airway management are derived only from adult populations. However, the objective is the same irrespective of patient age: proper securing of the airway and oxygenation of the patient.

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.

Supraglottic airway devices vs tracheal intubation in children: a quantitative meta-analysis of respiratory complications

BACKGROUND

Rate of perioperative respiratory complications between tracheal intubation (TI) and laryngeal mask airway remains unclear during pediatric anesthesia.

OBJECTIVES

The aim of the present meta-analysis was to compare the perioperative respiratory complications between laryngeal mask airway and TI.

METHODS

A meta-analysis of available controlled studies comparing laryngeal mask airway to TI was conducted. Studies including patients with airway infection were excluded. Data from each trial were combined to calculate the pooled odds ratios (OR) or mean difference (MD) and 95% confidence intervals.

RESULTS

The meta-analysis was performed on 19 studies. In 12 studies, patients were given muscle relaxation, and in 16 studies, ventilation was controlled. During recovery from anesthesia, the incidence of desaturation (OR = 0.34 [0.19-0.62]), laryngospasm (OR = 0.34 [0.2-0.6]), cough (OR = 0.18 [0.11-0.27]), and breath holding (0.19 [0.05-0.68]) was lower when laryngeal mask airway was used to secure the airway. Postoperative incidences of sore throat (OR = 0.87 [0.53-1.44]), bronchospasm (OR = 0.56 [0.25-1.25]), aspiration (1.33 [0.46-3.91]) and blood staining on the device (OR = 0.62 [0.21-1.82]) did not differ between laryngeal mask airway and TI. Results were homogenous across the studies, with the exceptions of blood staining on the device.

CONCLUSIONS

This meta-analysis found that the use of laryngeal mask airway in pediatric anesthesia results in a decrease in a number of common postanesthetic complications. It is therefore a valuable device for the management of the pediatric airway.

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.

The Professional Experience of Anaesthesiologists in Proper Inflation of Laryngeal Mask and Endotracheal Tube Cuff

OBJECTIVE

Cuffs inflated to inappropriately high pressures cause ischemia, reducing tracheal mucosal blood flow, while cuffs inflated at lower pressure than necessary give rise to inadequate ventilation, aspiration of gastric contents, or extubation due to air leakage. In this study, we aimed to investigate the effect of the experience of anaesthesia staff on endotracheal tube and laryngeal mask airway cuff inflation.

METHODS

The study included 348 elective patients scheduled to undergo surgery under general anaesthesia, with 34 anaesthesia technicians, 16 anaesthesia residents, and 12 anaesthesiologists with different years of professional experience. The participants were told to inflate the cuff balloon with air to the level of the pressure that was appropriate for them. No information was provided to the participants about the values of the cuff pressure pending the completion of all measurements. After placement of the laryngeal mask airway and endotracheal tube, the success of the procedure was checked by monitoring square-wave capnograph tracing and thoracoabdominal motion. Each participant performed the procedures on three patients, and the mean cuff pressures were measured.

RESULTS

There was no significant correlation between duration of experience of technicians, residents, and experts in using laryngeal mask airway pressure (r=-0.192/p=0.278, r=0.225/p=0.402, r=-0.476/p=0.118, respectively) and endotracheal tube (r=-0.306/p=0.079, r=-0.060/p=0.826, r=-0.478/0.116, respectively).

CONCLUSION

It has been concluded that professional experience does not contribute to achieving normal cuff pressure without monitoring. Introduction of the cuff manometer into routine anaesthesia practice will be useful, irrespective of anaesthesiologists' experience.

A randomized comparison of the laryngeal mask airway supreme™ and laryngeal mask airway unique™ in infants and children: does cuff pressure influence leak pressure?

BACKGROUND

The cuff pressure for optimal airway sealing with first-generation laryngeal mask airway has been shown to be 40 cm H(2)O in children. Currently, there are no data regarding the ideal intracuff pressure for the laryngeal mask airway Supreme (Supreme) in children.

OBJECTIVES

To compare the clinical performance of the laryngeal mask airway supreme with the laryngeal mask airway unique in infants and children.

MATERIALS AND METHODS

One hundred eighty children were assigned to receive either a Supreme or a laryngeal mask airway-U. We hypothesized higher airway leak pressure with the Supreme at both 40 cm H(2)O and 60 cm H(2)O, when compared with the laryngeal mask airway-U. Ease and time of insertion, insertion attempts, fiber optic examination, quality of airway, efficacy of mechanical ventilation, success of gastric tube placement (Supreme), incidence of gastric insufflation, and complications were also assessed.

RESULTS

Airway leak pressure at an intracuff pressure of 60 cm H(2)O for the Supreme was 17.4 (5.2) vs laryngeal mask airway-U at 18.4 (6.6) cm H(2)O and did not differ when compared to an intracuff pressure of 40 cm H(2)O for both devices; Supreme at 17.2 (5) vs laryngeal mask airway-U at 17.7 (6) cm H(2)O. The laryngeal mask airway-U was associated with higher first-attempt success rates. The Supreme was associated with less gastric insufflation than the laryngeal mask airway-U.

CONCLUSIONS

Intracuff pressures of 40 cm H(2)O may be sufficient for the Supreme in children, and there may be no added benefit of an intracuff pressure of 60 cm H(2)O, as leak pressures were similar. The Supreme may be preferred over the laryngeal mask airway-U for its lower rates of gastric insufflation and provision for gastric access when mechanical ventilation is utilized.

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.

Pediatric airway management: current practices and future directions

Management of a pediatric airway can be a challenge, especially for the non-pediatric anesthesiologists. Structured algorithms for an unexpected difficult pediatric airway have been missing so far. A recent step wise algorithm, based on the Difficult Airway society (DAS) adult protocol, is a step in the right direction. There have been some exciting advances in development of pediatric extra-glottic devices for maintaining ventilation, and introduction of pediatric versions of new 'non line of sight' laryngoscopes and optical stylets. The exact role of these devices in routine and emergent situations is still evolving. Recent advances in simulation technology has become a valuable tool in imparting psychomotor and procedural skills to trainees and allied healthcare workers. Moving toward the goal of eliminating serious adverse events during the management of routine and difficult pediatric airway, authors propose that institutions develop a dedicated Difficult Airway Service comprising of a team of experts in advanced airway management.

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.

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

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

Crossover comparison of airway sealing pressures of 1.5 and 2 size LMA-ProSeal™ and LMA-Classic™ in children, measured with the manometric stability test

OBJECTIVES

To compare airway sealing pressures, air leak, optimal positioning of the LMA-ProSeal™ and LMA-Classic™ in children.

METHODS

A crossover, randomized study was conducted in children aged 6 months-7 years weighing <20 kg scheduled for minor elective surgery under GA with sevoflurane. Either a 1.5 or 2-size LMA-ProSeal™ or LMA-Classic™ was inserted first. Optimal position of the devices was evaluated by fiberoptic bronchoscopy (FOB). Airway sealing pressures were determined under standardized conditions by the manometric stability test at the proximal end of the LMA device. Gas leak observed by auscultation over the neck and epigastrium was noted at these pressures.

RESULTS

Twenty-seven children of mean ages 29.48 ± 19.81 months and mean weight 11.23 ± 3.28 kg were included for evaluation. Airway sealing pressures were noted to be similar: 23.11 ± 8.28 cm H(2)O with LMA-ProSeal™ and 23.26 ± 8.21 cm H(2)O with LMA-Classic™. At these sealing pressures, air leak in the neck was observed in 21/27 children with LMA-ProSeal™ compared with 24/27 with LMA-Classic™ (P = 0.467). Optimal device positioning as viewed by FOB was seen in 14/27(51.8%) children with LMA-ProSeal™ and 15/27(55.6%) with LMA-Classic™. Airway sealing pressures with suboptimal position of LMA-ProSeal™ was 22.23 ± 10.23 cm H(2)O and with optimal position 23.93 ± 6.25 cm H(2)O (P = 0.612).

CONCLUSION

The LMA-ProSeal™ and LMA-Classic™ size 1.5 and 2 provide similar mean airway sealing pressures as assessed by the manometric stability test under standardized conditions, with similar air leak and optimal positioning.