The effects of prewarming the I-gel on fitting to laryngeal structure

Prewarming non-inflatable cuff laryngeal mask for mechanical ventilation: A systematic review and meta-analysis with trial sequential analysis

BACKGROUND

Non-inflatable cuff laryngeal masks are generally composed of thermoplastic material. The thermoplastic nature of the non-inflatable cuff will become soft and match the laryngeal anatomy better as it reaches body temperature after intubation. This meta-analysis aims to evaluate the clinical validity of prewarming non-inflatable cuff laryngeal mask before insertion.

METHODS

We searched PubMed, Cochrane Library, Embase, Web of Science, Ovid Medline, CNKI, Wan Fang Database and VIP Database to find randomized controlled trials (RCTs) researching the clinical validity of prewarming non-inflatable cuff laryngeal mask. The retrieval time is up to June 2022. Articles published in the English and Chinese languages were considered. Quality assessment was conducted with the Cochrane Collaboration's tool and GRADE (Grading of Recommendations Assessment, Development and Evaluation) method. Subgroup analyses and trial sequential analysis (TSA) were performed to control the risk of random errors. Publication bias was assessed by funnel plots and Egger's regression test. The outcomes included sealing pressure immediately after successful ventilation, the first-attempt intubation success rate and the incidence of postoperative pharyngeal pain.

RESULTS

Eight RCTs evaluating 683 patients were identified. Pooled results showed that compared to the control group, prewarming non-inflatable cuff laryngeal mask provided a higher sealing pressure immediately after successful ventilation (mean difference: 1.73 cm H2O; 95% confidence interval [CI]: 0.95-2.52; P < .0001; I2 = 16; high quality), higher first-attempt intubation success rate (risk ratio [RR]: 1.05; 95% CI: 1.01-1.09; P = .01; I2 = 26%; high quality, number needed to treat [NNT] = 22 [95% CI 12.5-100]) and lower incidence of postoperative pharyngeal pain (RR: 0.59, 95% CI: 0.46-0.75; P < .0001; I2 = 0; high quality, NNT = 6 [95% CI 4.17-9.09]). The results were confirmed by TSA.

CONCLUSION

Prewarming non-inflatable cuff laryngeal mask could provide better mechanical ventilation efficiency with higher sealing pressure, a higher first-attempt intubation success rate and a lower incidence of postoperative pharyngeal pain.

TRIAL REGISTRATION NUMBER

PROSPERO CRD42021245350.

Prewarming i-gel laryngeal mask for mechanical ventilation: a meta-analysis of randomised control trials and trial sequential analysis

OBJECTIVE

To systematically evaluate the efficiency of prewarming i-gel laryngeal mask for mechanical ventilation by meta-analysis and trial sequential analysis.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

Cochrane library, Web of Science, Ovid Medline and PubMed were searched from their inception to 31 August 2020. Only articles published in English language were considered.

METHODS

Randomised controlled trials (RCTs) comparing the efficiency of prewarming i-gel laryngeal mask versus keeping it at room temperature for mechanical ventilation were included. Primary outcome was sealing pressure immediately after successful ventilation. Secondary outcomes were the first-attempt insertion success rate and the incidence of postoperative pharyngeal pain. Two authors independently selected studies. Quality analysis was performed using the modified Jadad Scale. Trial sequential analysis (TSA) was used to control risk of random errors. Sensitivity analysis was done to assess the effect of a single study on the pooled estimates. Publication bias was assessed by funnel plots and Egger's regression test.

RESULTS

Four RCTs comprising 374 patients were included. The results of meta-analysis showed that compared with the control group, prewarming i-gel laryngeal mask provides a higher sealing pressure immediately after successful ventilation (mean difference 2.19 cm H₂O; 95% CI (1.17 to 3.21); p<0.0001; high quality), with firm evidence from TSA and lower publication bias (p=0.7372). No significant difference was observed in the first-attempt insertion success rate (relative ratio (RR) 1.06; 95% CI (1.00 to 1.12); p=0.07; high quality) with lower publication bias (p=0.1378). The TSA indicating further trials are required. No significant difference was assessed in the incidence of postoperative pharyngeal pain (RR 1.0; 95% CI (0.14 to 6.90); p=1.0; high quality).

CONCLUSION

Prewarming i-gel laryngeal mask provides higher sealing pressure compared with keeping it at room temperature. But prewarming i-gel laryngeal mask did not increase the first-attempt insertion success rate, nor did it decrease the incidence of postoperative pharyngeal pain.

Influence of head and neck positions on oropharyngeal seal pressure with Baska mask® versus I-gel™; A randomised clinical study

Background and Aims:

Oropharyngeal seal pressure (OSP) achieved by a supraglottic airway device holds due importance as it indicates the feasibility of positive pressure ventilation, the degree of airway protection from supra-cuff soiling and also relates to postoperative morbidity. The primary outcome measure was to assess and compare OSP in different head and neck positions with Baska mask^® and I-gel™. Secondary outcome measures were to compare peak inspiratory pressure (PIP), exhaled tidal volume (ETV), ease of insertion, time taken for insertion, number of attempts, intraoperative manipulations, and postoperative airway morbidity with both the devices.

Materials and Methods:

Seventy consenting adults scheduled for a variety of surgical procedures under general anesthesia were allocated to Group B and Group G using Baska mask^® and I-gel™ respectively. All statistical calculations were done using SPSS (Statistical Package for the Social Science). The comparison of quantitative variables between the study groups was done using Student t-test and within the variables was done by paired t-test. For comparing categorical data, Chi-square (χ²) test was performed.

Results:

OSP was significantly higher in group B than in group G in all head and neck positions (neutral 33 ± 2.8 vs. 23.2 ± 1.8, flexion 35.5 ± 2.5 vs. 25.2 ± 1.6, extension 30.6 ± 2.7 vs. 21.4 ± 1.7, right lateral 32.6 ± 2.8 vs. 23.0 ± 1.5. left lateral 32.6 ± 2.7 vs. 23.1 ± 1.7 cm H₂O, respectively) (P = 0.000). PIP increased significantly in group G as compared to group B in flexion. (P = 0.009). Baska mask^® had significantly higher ETV in flexion compared to I-gel™. (P = 0.009).

Conclusion:

Baska mask^® may provide a useful alternative to I-gel™ where the glottic seal has precedence over ease of insertion.

Does prewarming of i-gel improve insertion and ventilation in anaesthetised and paralysed patients? A prospective, randomised, control trial

Context:

I-gel are supraglottic airway devices with non-inflatable gel-like cuff that is believed to mould to body temperature, to seal the airway. Hence a pre-warmed i-gel may seal faster, provide better ventilation and superior leak pressure.

Aims:

To determine if pre-warming i-gel to 40°C improves insertion and efficacy of ventilation.

Methods and Materials:

A prospective, randomised, controlled trial was done on 64 patients requiring anaesthesia with muscle relaxation for short duration. For those in group W, i-gel warmed to 40°C for 15 minutes before insertion was used, whereas for those in group C, i-gel kept at room temperature (approximately 23°C) was used. The airway sealing pressure over time, number of attempts and time taken for a successful insertion were noted.

Statistical Analysis:

Mean sealing pressure between two groups was compared using independent sample t-test. Repeated Measures ANOVA was used to analyse mean sealing pressure at 0, 15 and 30 min. P value ≤0.05 was considered statistically significant.

Results:

Sealing pressure improves over time in both the groups but the mean sealing pressure was higher in group C when compared to group W at all points of time, however this was clinically and statistically insignificant. Ease of insertion, time for successful insertion, insertion attempts, intra-operative manoeuvres were all comparable between the groups with no adverse effects.

Conclusions:

Pre-warming of i-gel to 40°C does not improve the success rate of insertion or provide a higher sealing pressure in anaesthetised and paralysed patients when compared to i-gel at room temperature.

Extraglottic airway devices: technology update

Extraglottic airway devices (EADs) have revolutionized the field of airway management. The invention of the laryngeal mask airway was a game changer, and since then, there have been several innovations to improve the EADs in design, functionality, safety and construction material. These have ranged from changes in the shape of the mask, number of cuffs and material used, like rubber, polyvinylchloride and latex. Phthalates, which were added to the construction material in order to increase device flexibility, were later omitted when this chemical was found to have serious adverse reproductive outcomes. The various designs brought out by numerous companies manufacturing EADs resulted in the addition of several devices to the airway market. These airway devices were put to use, many of them with inadequate or no evidence base regarding their efficacy and safety. To reduce the possibility of compromising the safety of the patient, the Difficult Airway Society (DAS) formed the Airway Device Evaluation Project Team (ADEPT) to strengthen the evidence base for airway equipment and vet the new extraglottic devices. A preuse careful analysis of the design and structure may help in better understanding of the functionality of a particular device. In the meantime, the search for the ideal EAD continues.

Pre-warming the Streamlined Liner of the Pharynx Airway (SLIPA) improves fitting to the laryngeal structure: a randomized, double-blind study

Background

The Streamlined Liner of the Pharynx Airway (SLIPA), a type of supraglottic airway, has a non-inflatable cuff that softens at body temperature to fit the laryngeal structure. We investigated whether pre-warming of SLIPA to body temperature may improve insertion parameters.

Methods

Ninety adult patients were assigned equally randomized to either Group W or Group R. Anesthesia was induced using propofol, fentanyl, and rocuronium. In Group W, the SLIPA was warmed to 37 ° C before insertion, whereas in Group R, it was inserted at room temperature. The insertion time, oropharyngeal leak pressure, postoperative throat pain, blood staining, regurgitation, number of attempts at insertion, and difficulty of insertion were compared between the two groups.

Results

The insertion time was shorter in Group W than in Group R (3.60 [3.15–4.06] s vs. 6.00 [4.45–7.50] s; P < 0.001). Oropharyngeal leak pressure from the time of insertion until 3 min after insertion was significantly higher in Group W than in Group R (P < 0.05). Postoperative throat pain, measured using the visual analog scale, was lower in Group W than in Group R (0.00 [0.00–2.50] vs. 2.00 [0.00–4.50]; P = 0.006). The difficulty of insertion was lower in Group W than in Group R (P < 0.004). There were no significant differences in terms of blood staining, regurgitation, and number of attempts.

Conclusions

Pre-warming the SLIPA to body temperature has significant benefits compared to maintaining the device at room temperature. Specifically, insertion was easier, both insertion and fitting to the laryngeal structure could be performed more quickly, and the incidence of sore throat was reduced.

Trial registration

Clinical Research Information Identifier NCT01209000

Airway management evolution - in a search for an ideal extraglottic airway device

Extraglottic airway devices (EADs) are commonly used equipment for airway maintenance during elective procedures under general anaesthesia. They may be used also in other indications such as conduit for tracheal intubation or rescue airway device in prehospital medicine. Current classifications of the EADs lack systematic approach and therefore classification according to the sealing sites and sealing mechanisms is suggested in this review article. Modern EADs are disposable, latex-free devices made of plastic materials most commonly from polyvinylchloride (PVC). The bowl of uncuffed sealers is manufactured from different materials such as thermoplastic elastomers or ethylene-vinyl-acetate co-polymer. EADs create various physical forces exerted on the adjacent tissues which may contribute to different sealing characteristic of particular device or to variable incidence of postoperative complications. Desired features of an ideal EAD involve easy insertion, high insertion success rate even by inexperienced users, protection against aspiration of gastric contents and low incidence of postoperative complications such as sore throat, hoarseness, cough or swallowing difficulties.

Does prewarming the i-gel supraglottic airway device fit the larynx better compared to keeping it at room temperature for non-paralysed, sedated patients: a randomised controlled trial

OBJECTIVE

This study aimed to test the hypothesis that the i-gel supraglottic airway device would fit the larynx and provide better sealing pressure if prewarmed to 42°C relative to the device kept at room temperature in non-paralysed, sedated patients.

METHODS

A total of 74 adult patients were assigned to the warm (i-gel prewarmed to 42°C; W group; 37 patients) or the control (i-gel kept at room temperature; C group; 37 patients) groups. Anaesthesia was induced with propofol and fentanyl. The i-gel was prewarmed to 42°C for 30 min before insertion in the W group, but kept at room temperature (approximately 23°C) for the C group. The number of attempts made until successful insertion and sealing pressure were compared between the two groups.

RESULTS

Insertion was successful with one attempt in 35 cases each for the W and C groups. Two attempts were needed in two cases for the W group and one case for the C group. There was one failed attempt in the C group, but none in the W group. None of the differences between the two groups were significant (p=0.51). Sealing pressure was slightly, but not significantly, higher in the W group than in the C group (W group 22.6±6.1 cm H2O; C group 20.7±6.1 cm H2O; p=0.15).

CONCLUSIONS

Prewarming of the i-gel to 42°C did not increase the success rate of insertion, nor did it significantly increase sealing pressure in anaesthetised, non-paralysed patients. Our data suggest that we can keep the i-gel at room temperature for emergency airway management for non-paralysed, sedated patients.

TRIAL REGISTRATION NUMBER

University Medical Information Network, Japan 000012287.