Evidence for benefit vs novelty in new intubation equipment

Comparison of the supraglottic airway device BlockBusterTM and laryngeal mask airway Supreme in anaesthetised, paralyzed adult patients: a multicenter randomized controlled trial

BACKGROUND

This multicenter prospective, randomized controlled clinical trial compared the clinical performance of supraglottic airway device (SAD) BlockBuster^TM and laryngeal mask airway (LMA) Supreme for airway maintenance in anesthetized, paralyzed adult patients.

METHODS

A total of 651 adult patients scheduled for elective surgery in 13 hospitals were randomly allocated into BlockBuster group (n = 351) or Supreme group (n = 300). The primary outcome was oropharyngeal leak pressure (OLP). Duration and ease of insertion, fiberscopic view of positioning, airway manipulations, and complications were also assessed.

RESULTS

The OLP was significantly higher in BlockBuster group compared with Supreme group (29.9 ± 4.2 cmH₂O vs 27.4 ± 4.3 cmH₂O, p < 0.001). Success rate of insertion at the first attempt (90.2% vs 85.1%, p = 0.027), rate of optimal fiberscopic view (p = 0.002) and satisfactory positioning of SAD (p < 0.001) were significantly increased in BlockBuster group.

CONCLUSIONS

Both SAD BlockBuster^TM and LMA Supreme are safe, effective, and easy-to-use devices for airway maintenance in anesthetized, paralyzed adult patients, but the SAD BlockBuster^TM is superior to LMA Supreme in terms of OLP, success rate at the first attempt, and fiber-optic view of positioning.

TRIAL REGISTRATION

The trial is registered at www.chictr.org.cn (ChiCTR-ONC-16009105).

Comparison of the success with two bending angles for lighted stylet intubation in children: A prospective randomised study

BACKGROUND AND AIM

The bend angle of a lighted stylet is an important factor for successful orotracheal intubation. The aim of this study was to test the differences in the success of endotracheal intubation using lighted stylet with 70° versus 90° bend angles in children aged 4-6 years with normal airways.

METHODS

A total of 136 children with normal airways required orotracheal intubation were enrolled and were randomly allocated to the 90° or 70° bend angle groups. The first-attempt success rate was assessed as the primary outcome. The intubation time, lighted stylet search time, lighted stylet withdrawal time, hemodynamic responses, and perioperative complications were recorded as secondary outcomes.

RESULTS

All intubations were completed within three attempts (the 90° group, 63/5/0; the 70° group, 55/11/2). The first-attempt success rate was higher in the 90° group than that in the 70° group (92.6% [63/68 patients] versus 80.9% [55/68 patients], respectively; risk ratio, 1.15; 95% CI, 1.01-1.31; p = .04). Esophageal entry occurred in nine of 83 intubation attempts in the 70° group and two of 73 intubation attempts in the 90° group (risk ratio, 1.09; 95% CI, 1.01-1.19; p = .04). The intubation time and the lighted stylet search time were significantly shorter in the 90° group than that in the 70° group (intubation time: 12.2 ± 2.0 s versus 14.9 ± 2.6 s, respectively; mean difference, 2.65; 95% CI, 1.87-3.43; p < .01; effect size, 1.16; lighted stylet search time: 5.4 ± 1.0 s versus 8.0 ± 1.6 s, respectively; mean difference, 2.66; 95% CI, 2.21-3.12; p < .01; effect size, 1.95).

CONCLUSIONS

Lighted stylet intubation with a 90° bend angle improved the first-attempt success rate and reduced esophageal intubation in children aged 4-6 years with normal airways.

A comparison of the Macintosh laryngoscope, McGrath video laryngoscope, and Pentax Airway Scope in paediatric nasotracheal intubation

We evaluated the performance of the McGrath video laryngoscope and Pentax Airway Scope in comparison with the Macintosh laryngoscope for nasotracheal intubation in paediatric patients. For this, 108 patients were enrolled in an open-label, randomized controlled trial. Patients were randomly allocated to one of three groups based on use of the Macintosh laryngoscope, McGrath video laryngoscope, or Pentax Airway Scope. Time to intubation, the intubation difficulty, and the quality of navigation were compared among groups. The median nasotracheal intubation time [interquartile range] in the Macintosh group (33.5 [28.3–39.8] s) was significantly shorter than those of the McGrath (39.0 [32.0–43.0] s) and Pentax groups (43.0 [35.0–52.0] s). The difficulty of nasotracheal intubation was similar among all groups. When navigating and aligning the tube from the oropharynx into the glottic inlet, the cuff inflation method was required in significantly fewer patients for the Macintosh group (11.1%) than for the McGrath (48.6%) and Pentax (51.4%) groups. Thus, compared to the McGrath video laryngoscope and Pentax Airway Scope, the Macintosh laryngoscope allowed shorter nasotracheal intubation times and better facilitated tracheal navigation, requiring less use of the cuff inflation method to navigate the tracheal tube into the glottic inlet.

Intubation of prehospital patients with curved laryngoscope blade is more successful than with straight blade

OBJECTIVE

Direct laryngoscopy can be performed using curved or straight blades, and providers usually choose the blade they are most comfortable with. However, curved blades are anecdotally thought of as easier to use than straight blades. We seek to compare intubation success rates of paramedics using curved versus straight blades.

METHODS

Design: retrospective chart review.

SETTING

hospital-based suburban ALS service with 20,000 annual calls.

SUBJECTS

prehospital patients with any direct laryngoscopy intubation attempt over almost 9years. First attempt and overall success rates were calculated for attempts with curved and straight blades. Differences between the groups were calculated.

RESULTS

2299 patients were intubated by direct laryngoscopy. 1865 had attempts with a curved blade, 367 had attempts with a straight blade, and 67 had attempts with both. Baseline characteristics were similar between groups. First attempt success was 86% with a curved blade and 73% with a straight blade: a difference of 13% (95% CI: 9-17). Overall success was 96% with a curved blade and 81% with a straight blade: a difference of 15% (95% CI: 12-18). There was an average of 1.11 intubation attempts per patient with a curved blade and 1.13 attempts per patient with a straight blade (2% difference, 95% CI: -3-7).

CONCLUSIONS

Our study found a significant difference in intubation success rates between laryngoscope blade types. Curved blades had higher first attempt and overall success rates when compared to straight blades. Paramedics should consider selecting a curved blade as their tool of choice to potentially improve intubation success.

Comparison of three types of intubation stylets for tracheal intubation with a McGrath MAC® video laryngoscope by novice intubators in simulated cervical immobilisation: A randomised crossover manikin study

Introduction:

Tracheal intubation using video laryngoscopes has been a better approach for trauma patients requiring cervical immobilisation. The aim of this study was to compare the time to successful intubation by novice intubators using three types of intubation stylets with the new McGrath MAC video laryngoscope in a manikin model.

Methods:

This was a randomised crossover manikin study. The participants performed tracheal intubations using three intubation stylets (arcuate shape malleable stylet, McGrath MAC-shaped malleable stylet and McGrath MAC-shaped rigid stylet) in a difficult airway model with cervical immobilisation. The order of the stylets was randomised. The primary outcome was the time to successful intubation. The secondary outcomes were the overall success rates, incidence of dental trauma and ease of intubation. All intubation attempts were assessed by trained assistants. The data were analysed using a multilevel model followed by Tukey’s post hoc test.

Results:

A total of 68 nurses participated in this study. The time to successful intubation of the McGrath MAC-shaped malleable stylet was significantly shorter than that of the arcuate shape malleable stylet (24.5 (18.0–51.0) s vs 31.5 (21.0–89.0) s, p = 0.005). The overall success rate of the McGrath MAC-shaped malleable stylet was also higher than that of the arcuate shape malleable stylet ( p = 0.047). The participants indicated that intubation was easier using the McGrath MAC-shaped malleable stylet compared with the other stylets.

Conclusion:

The McGrath MAC-shaped malleable stylet, when used by novice intubators, may be an optimal stylet shape for tracheal intubation using the McGrath MAC in cervical immobilisation.

Guidelines for the management of tracheal intubation in critically ill adults

These guidelines describe a comprehensive strategy to optimize oxygenation, airway management, and tracheal intubation in critically ill patients, in all hospital locations. They are a direct response to the 4^th National Audit Project of the Royal College of Anaesthetists and Difficult Airway Society, which highlighted deficient management of these extremely vulnerable patients leading to major complications and avoidable deaths. They are founded on robust evidence where available, supplemented by expert consensus opinion where it is not. These guidelines recognize that improved outcomes of emergency airway management require closer attention to human factors, rather than simply introduction of new devices or improved technical proficiency. They stress the role of the airway team, a shared mental model, planning, and communication throughout airway management. The primacy of oxygenation including pre- and peroxygenation is emphasized. A modified rapid sequence approach is recommended. Optimal management is presented in an algorithm that combines Plans B and C, incorporating elements of the Vortex approach. To avoid delays and task fixation, the importance of limiting procedural attempts, promptly recognizing failure, and transitioning to the next algorithm step are emphasized. The guidelines recommend early use of a videolaryngoscope, with a screen visible to all, and second generation supraglottic airways for airway rescue. Recommendations for emergency front of neck airway are for a scalpel-bougie-tube technique while acknowledging the value of other techniques performed by trained experts. As most critical care airway catastrophes occur after intubation, from dislodged or blocked tubes, essential methods to avoid these complications are also emphasized.

Current evidence for the use of C-MAC videolaryngoscope in adult airway management: a review of the literature

The C-MAC videolaryngoscope is the first Macintosh-typed videolaryngoscope. Since the advent of its original version video Macintosh system in 1999, this device has been modified several times. A unique feature of C-MAC device is its ability to provide the 2 options of direct and video laryngoscopy with the same device. The available evidence shows that in patients with normal airways, C-MAC videolaryngoscope compared with direct laryngoscopy can provide comparable or better laryngeal views and exerts less force on maxillary incisors, but does not offer conclusive benefits with regard to intubation time, intubation success, number of intubation attempts, the use of adjuncts, and hemodynamic responses to intubation. In patients with predicted or known difficult airways, C-MAC videolaryngoscope can achieve a better laryngeal view, a higher intubation success rate and a shorter intubation time than direct laryngoscopy. Furthermore, the option to perform direct and video laryngoscopy with the same device makes C-MAC videolaryngoscope exceptionally useful for emergency intubation. In addition, the C-MAC videolaryngoscope is a very good tool for tracheal intubation teaching. However, tracheal intubation with C-MAC videolaryngoscope may occasionally fail and introduction of C-MAC videolaryngoscope in clinical practice must be accompanied by formal training programs in normal and difficult airway managements.

[Comparison of different stylets used for intubation with the C-MAC D-Blade® Videolaryngoscope: a randomized controlled study]

OBJECTIVE

The angle of the C-MAC D-Blade^® videolaryngoscope, which is used for difficult airway interventions, is not compatible with routinely used endotracheal tubes.

METHODS

A prospective randomized crossover study was performed comparing five intubation methods for use with standardized airways, including using different stylets or no stylet: Group HS, hockey-stick stylet; Group DS, D-blade type stylet; Group CS, CoPilot^® videolaryngoscope rigid stylet^®; Group GEB, gum elastic bougie; and Group NS, no stylet. A manikin was used to simulate difficult intubation with a Storz C-MAC D-Blade^® videolaryngoscope. The duration of each intubation stage was evaluated.

RESULTS

Participants in this study (33 anesthesiology residents and 20 anesthesiology experts) completed a total of 265 intubations. The number of attempts made using no stylet was significantly greater than those made for the other groups (p<0.05 for group NS- group GEB, group NS- group DS, group NS- group CS and group NS- group HS). The duration to pass the vocal cords significantly differed among all groups (p<0.001). The total intubation duration was shortest when using D-blade stylet, CoPilot stylet and hockey stick stylet. Although no difference was observed between stylet groups, a significant difference was found between each of these three and no stylet and gum elastic bougie (p<0.05 and p<0.001, respectively).

CONCLUSION

Use of the correct stylet leads to a more efficient use of the Storz C-MAC D-Blade^®. In our study, the use of the D-blade stylet, the CoPilot stylet and the hockey stick stylet provided quicker intubation, allowed easier passage of the vocal cords, and decreased the total intubation duration. To confirm the findings of our study, randomized controlled human studies are needed.

Transfer of skills and comparison of performance between king vision® video laryngoscope and macintosh blade following an AHA airway management course

Background

To potentially optimize intubation skill teaching in an American Heart Association® Airway Management Course® for novices, we investigated the transfer of skills from video laryngoscopy to direct laryngoscopy and vice versa using King Vision® and Macintosh blade laryngoscopes respectively.

Methods

Ninety volunteers (medical students, residents and staff physicians) without prior intubation experience were randomized into three groups to receive intubation training with either King Vision® or Macintosh blade or both. Afterwards they attempted intubation on two human cadavers with both tools. The primary outcome was skill transfer from video laryngoscopy to direct laryngoscopy assessed by first attempt success rates within 60 s. Secondary outcomes were skill transfer in the opposite direction, the efficacy of teaching both tools, and the success rates and esophageal intubation rates of Macintosh blade versus King Vision®.

Results

Performance with the Macintosh blade was identical following training with either Macintosh blade or King Vision® (unadjusted odds ratio [OR] 1.09, 95% confidence interval [95% CI] 0.5–2.6). Performance with the King Vision® was significantly better in the group that was trained on it (OR 2.7, 95% CI 1.2–5.9). Success rate within 60 s with Macintosh blade was 48% compared to 52% with King Vision® (OR 0.85, 95% CI 0.4–2.0). Rate of esophageal intubations with Macintosh blade was significantly higher (17% versus 4%, OR 5.0, 95% CI 1.1–23).

Conclusions

We found better skill transfer from King Vision® to Macintosh blade than vice versa and fewer esophageal intubations with video laryngoscopy. For global skill improvement in an airway management course for novices, teaching only video laryngoscopy may be sufficient. However, success rates were low for both devices.

Electronic supplementary material

The online version of this article (doi:10.1186/s12871-016-0296-9) contains supplementary material, which is available to authorized users.

Retention of laryngoscopy skills in medical students: a randomised, cross-over study of the Macintosh, A.P. Advance(™) , C-MAC(®) and Airtraq(®) laryngoscopes

In addition to being effective and easy to learn how to use, the ideal laryngoscope should be associated with minimal reduction in skill performance during gaps in practice over time. We compared the time taken to intubate the trachea of a manikin by novice medical students immediately after training, and then after 1 month, with no intervening practice. We designed a two-period, four-group, randomised, cross-over trial to compare the Macintosh, Venner(™) A.P. Advance(™) with difficult airway blade, C-MAC(®) with D-Blade and Airtraq(®) with wireless video-viewer. A bougie was used to aid intubation with the Macintosh and the C-MAC. After training, there was no significant difference in median (IQR [range]) intubation time using the videolaryngoscopes compared with the Macintosh, which took 30 (26.5-35 [12-118])s. One month later, the intubation time was longer using the C-MAC (41 (29.5-52 [20-119])s; p = 0.002) and A.P. Advance (40 (28.5-57.5 [21-107])s; p = 0.0003)m compared with the Macintosh (27 (21-29 [16-90])s); there was no difference using the Airtraq (27 (20.5-32.5 [15-94])s; p = 0.258) compared with the Macintosh. While skill acquisition after a brief period of learning and practice was equal for each laryngoscope, performance levels differed after 1 month without practice. In particular, the consistency of performance using the C-MAC and A.P. Advance was worse compared with the Macintosh and the Airtraq. While the clinical significance of this is doubtful, we believe that reliable and consistent performance at laryngoscopy is desirable; for the devices that we tested, this requires regular practice.

Comparison of Tracheal Intubation Using the Storz's C-Mac D-blade(TM) Video-Laryngoscope Aided by Truflex(TM) Articulating Stylet and the Portex(TM) Intubating Stylet

Background:

Tracheal intubation using Storz’s C-Mac D-blade^TM videolaryngoscope is associated with difficult negotiation of the tracheal tube into the glottis due to steep angulation of its blade.

Objectives:

In this study, we hypothesized that Truflex^TM articulating stylet with its ability to dynamically tailor the ETT shape to patients’ oropharyngeal anatomy would be better suited to the D-blade angulation and ease tracheal intubation compared to Portex^TM intubation stylet.

Patients and Methods:

Following approval by the Ethical Issues Committee and informed consent, 218 ASA I and II patients of either sex were enrolled in this interventional, single-blind, randomized controlled trial. Tracheal intubation was performed following a uniform general anesthetic technique using the Storz’s C-Mac D-blade^TM videolaryngoscope aided by either Truflex^TM articulating stylet or the Portex^TM intubation stylet by an experienced anesthesiologist. The outcome measures included success or failure to intubate in the first attempt, total intubation time, hemodynamic disturbances, trauma if any and user satisfaction.

Results:

The number of patients in whom intubation was successful in the first attempt was significantly higher by using Truflex™ articulating stylet (99.1%) compared to Portex^TM intubation stylet (90.0%; P-Value = 0.003). User satisfaction grade was significantly better while using Truflex^TM articulating stylet (8.5 ± 0.88) compared to the Portex^TM intubation stylet (8.23 ± 0.99; P-Value = 0.035). We did not observe any significant difference in total intubation time, hemodynamic disturbances or trauma.

Conclusions:

Storz’s C-Mac D-blade^TM videolaryngoscope provides grade I Cormack and Lehane’s glottic view in 99.1% patients. First attempt successful tracheal intubation and user satisfaction significantly improved by Truflex^TM articulating stylet compared to the Portex^TM intubation stylet.

Difficult Airway Society 2015 guidelines for management of unanticipated difficult intubation in adults

These guidelines provide a strategy to manage unanticipated difficulty with tracheal intubation. They are founded on published evidence. Where evidence is lacking, they have been directed by feedback from members of the Difficult Airway Society and based on expert opinion. These guidelines have been informed by advances in the understanding of crisis management; they emphasize the recognition and declaration of difficulty during airway management. A simplified, single algorithm now covers unanticipated difficulties in both routine intubation and rapid sequence induction. Planning for failed intubation should form part of the pre-induction briefing, particularly for urgent surgery. Emphasis is placed on assessment, preparation, positioning, preoxygenation, maintenance of oxygenation, and minimizing trauma from airway interventions. It is recommended that the number of airway interventions are limited, and blind techniques using a bougie or through supraglottic airway devices have been superseded by video- or fibre-optically guided intubation. If tracheal intubation fails, supraglottic airway devices are recommended to provide a route for oxygenation while reviewing how to proceed. Second-generation devices have advantages and are recommended. When both tracheal intubation and supraglottic airway device insertion have failed, waking the patient is the default option. If at this stage, face-mask oxygenation is impossible in the presence of muscle relaxation, cricothyroidotomy should follow immediately. Scalpel cricothyroidotomy is recommended as the preferred rescue technique and should be practised by all anaesthetists. The plans outlined are designed to be simple and easy to follow. They should be regularly rehearsed and made familiar to the whole theatre team.

Evaluation of Karl Storz CMAC Tip™ device versus traditional airway suction in a cadaver model

Introduction

We compared the efficacy of Karl Storz CMAC Tip™ with inline suction to CMAC with traditional suction device in cadaveric models simulating difficult airways, using media mimicking pulmonary edema and vomit.

Methods

This was a prospective, cohort study in which we invited emergency medicine faculty and residents to participate. Each participant intubated 2 cadavers (one with simulated pulmonary edema and one with simulated vomit), using CMAC with inline suction and CMAC with traditional suction. Thirty emergency medicine providers performed 4 total intubations each in a crossover trial comparing the CMAC with inline suction and CMAC with traditional suction. Two intubations were performed with simulated vomit and two with simulated pulmonary edema. The primary outcome was time to successful intubation; and the secondary outcome was proportion of successful intubation.

Results

The median time to successful intubation using the CMAC with inline suction versus traditional suction in the pulmonary edema group was 29s and 30s respectively (p=0.54). In the vomit simulation, the median time to successful intubation was 40s using the CMAC with inline suction and 41s using the CMAC with traditional suction (p=0.70). There were no significant differences in time to successful intubation between the 2 devices. Similarly, the proportions of successful intubation were also not statistically significant between the 2 devices. The proportions of successful intubations using the inline suction were 96.7% and 73.3%, for the pulmonary edema and vomit groups, respectively. Additionally using the handheld suction device, the proportions for the pulmonary edema and vomit group were 100% and 66.7%, respectively.

Conclusion

CMAC with inline suction was no different than CMAC with traditional suction and was associated with no statistically significant differences in median time to intubation or proportion of successful intubations.

Tracheal intubation in patients with anticipated difficult airway using Boedeker intubation forceps and McGrath videolaryngoscope

BACKGROUND

Videolaryngoscopes with sharp angulated blades improve the view of the vocal cords but this does not necessarily result in higher success rates of intubation The aim of this study was to evaluate the efficacy of using Boedeker intubation forceps in conjunction with McGrath Series 5 Videolaryngoscope (MVL) in patients with predictors for difficult intubation.

METHODS

The study was conducted at the Department of Anaesthesia, Copenhagen University Hospital from September to December 2013. Patients with one or more predictors of difficult intubation scheduled for general anaesthesia were assessed for eligibility. Patients were intubated using Boedeker intubation forceps and MVL. The primary endpoint was time to intubation. The secondary endpoints were intubation success rate, number of intubation attempts, intubation conditions and post-operative hoarseness.

RESULTS

Thirty-three patients were assessed for eligibility, and 25 patients were included in the study with a median SARI score of 3 (IQR 3-4). Twenty-two (88%, 95% confidence interval [74-100%]) of the patients were successfully intubated by the method with a median time to intubation of 115 s (IQR 78-247). Steering and advancement of the tube were reported as acceptable in 21 (84%) and 22 cases (88%), respectively, and excellent in 10 cases (45%) for both measures. Ten cases (40%) were intubated on the first attempt. There were three cases (12%) of failed intubation; in these cases, successful intubation was obtained by using a styletted tube.

CONCLUSION(S)

Most patients with anticipated difficult intubation can be successfully intubated with Boedeker intubation forceps and MVL. However, endotracheal tube placement failed in 3/25 patients despite a good laryngeal view.

Video laryngoscopes and the obstetric airway

The pitfalls surrounding securing the airway in the obstetric patient are well documented. From Tunstall's original failed intubation drill onwards, there has been progress both in recognition of the difficulties of airway management in the pregnant patient and development of algorithms to enhance patient safety. Current trends in obstetric anaesthesia have resulted in a significant decrease in exposure of anaesthetists, especially trainees, to caesarean section under general anaesthesia, compounding the difficulties in safely managing the airway. Video laryngoscopes have recently appeared in airway algorithms. They improve glottic visualisation and are useful in the management of the difficult non-obstetric airway, including those in morbidly obese patients and in the setting of a rapid-sequence induction. There is growing interest in the potential use of video laryngoscopes in the obstetric population and as a teaching tool to maximise training opportunities.

A review of video laryngoscopes relevant to the intensive care unit

The incidence of difficult direct intubation in the intensive care unit (ICU) is estimated to be as high as 20%. Recent advances in video-technology have led to the development of video laryngoscopes as new intubation devices to assist in difficult airway management. Clinical studies indicate superiority of video laryngoscopes relative to conventional direct laryngoscopy in selected patients. They are therefore an important addition to the armamentarium of any clinician performing endotracheal intubation. We present a practical review of commonly available video laryngoscopes with respect to design, clinical efficacy, and safety aspects relevant to their use in the ICU.

[Tooth injury in anaesthesiology]

BACKGROUND AND OBJECTIVES

Dental injury is the most common complication of general anaesthesia and has significant physical, economic and forensic consequences. The aim of this study is to review on the characteristics of dental injury associated with anaesthesiology and existing methods of prevention.

CONTENTS

In this review, the time of anaesthesia in which the dental injury occurs, the affected teeth, the most frequent type of injury, established risk factors, prevention strategies, protection devices and medico-legal implications inherent to its occurrence are approached.

CONCLUSIONS

Before initiating any medical procedure that requires the use of classic laryngoscopy, a thorough and detailed pre-aesthetic evaluation of the dental status of the patient is imperative, in order to identify teeth at risk, analyze the presence of factors associated with difficult intubation and outline a prevention strategy that is tailored to the risk of dental injury of each patient.

An awake double lumen endotracheal tube intubation using the Clarus Video System in a patient with an epiglottic cyst: a case report

A 54-year-old male patient was scheduled for an elective pylorus-preserving pancreaticoduodenectomy combined with video-assisted thoracic surgery at our hospital. This patient had a history of intubation failure in other institutions due to an epiglottic cyst. An airway assessment of the patient was normal. A preoperative laryngoscopy revealed a bulging epiglottic mass covering most of the epiglottis and occupying most of the pharyngeal space. The patient was administered intravenous midazolam 1 mg, fentanyl 50 µg, and glycopyrrolate 0.2 mg. A bilateral superior laryngeal nerve block was then performed with 2% lidocaine 2 ml on each side. A 10% lidocaine spray was applied on to the oropharynx. After preoxygenation with 100% oxygen over 10 minutes, a rigid fiberscope with an optical stylet loaded with a 37 Fr double lumen endotracheal tube was inserted orally and passed into the glottic aperture. The patient was fully awakened after surgical procedure and was transferred to the recovery room after extubation.

Tracheal intubation with a flexible intubation scope versus other intubation techniques for obese patients requiring general anaesthesia

BACKGROUND

The prevalence of obesity (body mass index (BMI) > 30 kg/m(2)) is increasing in both developed and developing countries, leading to a rise in the numbers of obese patients requiring general anaesthesia. Obese patients are at increased risk of anaesthetic complications, and tracheal intubation can be more difficult. Flexible intubation scopes (FISs) are recommended as an alternative method of intubation in these patients. Intubation with an FIS is considered an advanced method, requiring training and experience; therefore it may be underused in clinical practice. Patient outcomes following intubation with these scopes compared with other devices have not been systematically reviewed.

OBJECTIVES

We wished to compare the safety and effectiveness of a flexible intubation scope (FIS) used for tracheal intubation in obese patients (BMI > 30 kg/m(2)) with other methods of intubation, including conventional direct laryngoscopy, non-standard laryngoscopy and the use of intubating supraglottic airway devices. We aimed to compare the frequency of complications, as well as process indicators, such as time taken for intubation and the proportion of first attempts that were successful, between groups using the different methods of intubation.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE and two trial registers on 18 January 2013, and performed reference checking and citation searching and contacted study authors to identify additional studies.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) of participants aged 16 years and older with a BMI > 30 kg/m(2) that had compared the use of an FIS for tracheal intubation with any one of three comparison groups: direct laryngoscopy; non-standard laryngoscopy (including indirect laryngoscopy using a videolaryngoscope (VLS) or a rigid or semi-rigid stylet); or intubation of supraglottic airway devices (SADs).

DATA COLLECTION AND ANALYSIS

We used standard methodological approaches expected by The Cochrane Collaboration, including independent review of titles, data extraction and risk of bias assessment by two investigators.

MAIN RESULTS

Three eligible studies were identified, all comparing the use of an FIS with a VLS. All studies were small, with only 131 participants in total across all trials. It was impossible for the intubators to be unaware of the device used, so all studies were at high risk of performance and detection bias for outcomes related to intubation. Because of substantial differences in design between the studies, we did not combine their results in meta-analyses. The results for all outcomes were inconclusive, with no differences noted between FIS and VLS. Two studies with experienced intubators reported first attempt success rates greater than 70% in both groups and less than 5% of participants requiring a change of intubation device. No evidence was found of any difference in difficulty or time taken between FIS and VLS intubation. No serious complications or airway trauma was reported, so we were unable to address these outcomes. Bleeding was uncommon, occurring in less than 5% of participants, and we found no evidence that it was more likely in the FIS group. One small study with a novice intubator reported no successful intubations using an FIS and compared with the use of an intubating SAD and stylet, as well as with a VLS. With only five participants in each group, no conclusions can be drawn from these additional comparisons.

AUTHORS' CONCLUSIONS

The evidence base is sparse, and the existing literature does not address the clinical questions of patient safety posed by this review. We are therefore unable to draw any conclusions on safety or effectiveness. More primary research is needed to investigate optimal intubation techniques in obese patients, and new studies should be powered to detect differences in complications and in success rates rather than process measures such as speed, which are of limited clinical importance.