Laryngoscopy: time to change our view

Comparison of conventional C-MAC video laryngoscope guided intubation by anesthesia trainees with and without Frova endotracheal introducer: A randomized clinical trial

BACKGROUND AND AIMS

Successful intubation with video laryngoscopes necessitates good hand-eye coordination and the use of intubation adjuncts like bougie and stylet. We proposed this study to find whether using Frova introducer with C-MAC video laryngoscope will reduce the intubation time in trainee anesthesiologists.

MATERIAL AND METHODS

We enrolled 140 adults without any difficult airway predictors. They were randomly assigned to undergo C-MAC video laryngoscope guided intubation by anesthesia residents using tracheal tube preloaded over Frova introducer (n = 70) or without Frova introducer (n = 70). Primary outcome was the intubation time. Secondary outcomes were the number of redirections of tracheal tube or Frova introducer toward glottis, need for external laryngeal maneuvers (ELMs), first attempt intubation success rate, and ease of intubation.

RESULTS

The median actual intubation time (IQR) in Frova and non-Frova group, respectively, were 25.46 (28.11-19.80) and 19.96 (26.59-15.52) s (P = 0.001). The number of redirections of TT or Frova introducer toward glottis, first attempt success rate, and ease of intubation were comparable. The need for ELMs [n (%)] was 15 (21.4) and 26 (37.1) in Frova and non-Frova group, respectively (P = 0.04).

CONCLUSION

Frova introducer guided endotracheal intubation with C-MAC videolaryngoscope in patients with normal airways had a marginally prolonged intubation time with a significant reduction in the need of external laryngeal manoeuvres but with a comparable number of redirections and attempts. Further research is needed to generalize these findings to patients with difficult airways.

Cervical Spine Movement and Ease of Intubation Using Truview or McCoy Laryngoscope in Difficult Intubation

STUDY DESIGN

Prospective, observational, analytical, randomized control trial.

OBJECTIVE

To compare cervical spine movement for best laryngoscopic view and ease of intubation using Truview or McCoy laryngoscope in anticipated difficult intubation.

SUMMARY OF BACKGROUND DATA

The addition of modified laryngoscope blade to the anesthesiologist's armamentarium adds flexibility and improves the skill of the anesthetist, which benefits the patients.

METHODS

One hundred patients of American Society of Anesthesiologists status I and II with predicted difficult intubation score ≥5 were divided into two groups: Group A (n = 50): intubation done with McCoy laryngoscope and Group B (n = 50): intubation done with Truview laryngoscope and compared for the ease of intubation using intubation difficulty scale (IDS), cervical spine movement, and hemodynamic alterations.

RESULTS

The total IDS determining the ease of tracheal intubation was better in Group B than Group A. On comparing the variables of IDS score, there was no difference between the two groups except 14 (28%) patients in Group A required application of external laryngeal pressure, whereas only five (10%) patients had this difficulty in Group B. It was seen that craniocervical extension was significantly less (2.5 times) in Group B as compared to Group A.

CONCLUSION

In anticipated difficult intubation, Truview improves the laryngeal view, causes less movement at cervical spine, which could be more helpful in patients with restricted neck mobility, and has lesser complications.

LEVEL OF EVIDENCE

2.

Pioneers of Laryngoscopy: Indirect, Direct and Video Laryngoscopy

Airway management is one of the core skills of the anaesthetist and various techniques of airway management have developed over many years. Initially, the only view of the glottis that could be obtained was an indirect view (indirect laryngoscopy). Late in the 19th century, a direct view of the glottis was obtained via various direct laryngoscopes. Currently, in the early 21st century, there has been a return to indirect laryngoscopy via videolaryngoscopy using a videolaryngoscope. The aim of this paper is to give a historical overview of the development of both direct and indirect laryngoscopy.

Facilitation of fiberoptic nasotracheal intubation with magnesium sulfate: A double-blind randomized study

Background:

A double-blinded, prospective, and randomized study was designed to determine the efficacy and tolerability of intravenous (IV) magnesium sulfate (MgSO₄) to facilitate fiberoptic bronchoscopic (FOB) nasotracheal intubations.

Patients and Methods:

A total of 120 patients scheduled to undergo elective awake fiberoptic nasotracheal intubation, while they were anesthetized for elective surgery were randomly allocated to one of three groups: The control Group S (n = 40) received 100 ml (50 ml 0.9% saline + 50 ml paracetamol) was infused in 10 min and direct IV 5 ml 0.9% normal saline, Group MD (n = 40): Received midazolam IV in a dose of 0.07 mg/kg in 5 ml 0.9% normal saline and 100 ml 0.9% was infused in 10 min and Group MS (n = 40): IV 45 mg/kg MgSO₄ 10 min in 100 ml of 0.9% normal saline through 10 min and direct IV 5 ml 0.9% normal saline.

Results:

Time required for nasotracheal intubation was significantly less in group Groups MD and MS, as compared with the control group, but not significant between the two groups. (Group MD: 9.05 + 1.95 min, Group MS 3.75 + 0.75 min and Group S 16.85 + 1.7 min). However, the number of fiberoptic intubation was significantly more in the MD and MS groups, as compared with the control group. Easy intubation (control group: 0, Group MD: 25 and Group MS: 35), moderate difficulty (control group: 5, Group MD: 12 and Group MS: 4) and difficult (control group: 35, Group MD: 3 and Group MS: 1). Procedure adverse events were significantly lower in Group MS. None of the patients in Group MS had procedure hypoxia, but it occurred in 10 patients of Group MD and 20 patients in Group S. Six patients in Group S and two in Group MD had procedure apnea whereas, none of the patients in the MS group experienced this. After medication and just before intubation heart rate and mean arterial pressure were significantly less in Groups MD and MS, as compared to the control group (Group MD: 77 + 7.7 beat/min, Group MS: 70 + 5.6 beat/min and Group S: 80 + 7.8 beat/min) (Group MD: 90 + 8.5 mmHg, Group MS: 80 + 8.1 mmHg and Group S: 105 + 10.5 mmHg). This difference however, significant between Group MD and Group MS.

Conclusion:

Intravenous MgSO₄ improved awaken FOB intubation without adverse hemodynamic or respiratory effects.

Preanesthetic assessment data do not influence the time for tracheal intubation with Airtraq™ video laryngoscope in obese patients

PURPOSE

this study investigated the influence of anatomical predictors on difficult laryngoscopy and orotracheal intubation in obese patients by comparing Macintosh and Airtraq™ laryngoscopes.

METHODS

from 132 bariatric surgery patients (body mass index ≥ 35 kgm(-1)), cervical perimeter, sternomental distance, interincisor distance, and Mallampati score were recorded. The patients were randomized into two groups according to whether a Macintosh (n=64) or an Airtraq™ (n=68) laryngoscope was used for tracheal intubation. Time required for intubation was the first outcome. Cormack-Lehane score, number of intubation attempts, the Macintosh blade used, any need for external tracheal compression or the use of gum elastic bougie were recorded. Intubation failure and strategies adopted were also registered.

RESULTS

intubation failed in two patients in the Macintosh laryngoscope group, and these patients were included as worst cases scenario. The intubation times were 36.9+22.8s and 13.7+3.1s for the Macintosh and Airtraq™ laryngoscope groups (p<0.01), respectively. Cormack-Lehane scores were also lower for the Airtraq™ group. One patient in the Macintosh group with intubation failure was quickly intubated with the Airtraq™. Cervical circumference (p<0.01) and interincisor distance (p<0.05) influenced the time required for intubation in the Macintosh group but not in the Airtraq™ group.

CONCLUSION

in obese patients despite increased neck circumference and limited mouth opening, the Airtraq™ laryngoscope affords faster tracheal intubation than the Macintosh laryngoscope, and it may serve as an alternative when conventional laryngoscopy fails.

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.

Standard clinical risk factors for difficult laryngoscopy are not independent predictors of intubation success with the GlideScope

STUDY OBJECTIVES

To determine whether the first-attempt tracheal intubation incidence using the GlideScope videolaryngoscope is higher in patients with predicted increased risk of difficult laryngoscopy, and to assess the ability of other a priori defined standard risk factors to predict first-attempt intubation success, in aggregate and by forming scores.

DESIGN

Prospective study.

SETTING

Operating room in a tertiary-care academic center.

PATIENTS

357 patients intubated with the GlideScope for nonemergent general anesthesia.

INTERVENTIONS AND MEASUREMENTS

Mallampati airway class was used to create two groups of patients, one with higher and the other, lower, potential difficult laryngoscopy (Mallampati classes 3-4 and 1-2, respectively). Intubation success on the first attempt with the GlideScope videolaryngoscope in patients with a Mallampati class 3 or 4 airway versus those with Mallampati class 1 or 2 airway was tested. We also evaluated the predictive ability of the Mallampati airway class (1 and 2 vs 3 and 4) along with 9 other possible predictors of difficult intubation on first-attempt intubation success: gender, age, body mass index, level of training within our anesthesia residency program (Clinical Anesthesia Resident years 1, 2, and 3), ASA physical status, mouth opening, thyromental distance, neck flexion, and neck extension.

MAIN RESULTS

None of the standard predictors of difficult intubation was significantly associated with outcome after adjusting for other predictors. A multivariable model containing the aggregate set of variables predicted outcome significantly better than a risk score formed as the sum of 10 predictors ("Risk 10"; P = 0.0176).

CONCLUSIONS

With GlideScope-assisted tracheal intubation, Mallampati airway class is not an independent risk factor for difficult intubation. Other standard clinical risk factors of difficulty with direct laryngoscopy also do not appear to be individually predictive of first-attempt success of tracheal intubation.

An evidence-based approach to airway management: is there a role for clinical practice guidelines?

Complications arising out of airway management represent an important cause of anaesthesia-associated morbidity and mortality. Anaesthetic practice itself can lead to preventable harm, a particular example being persistent attempts at direct laryngoscopy, that results in delay in employing alternative strategies (or devices) when intubation is difficult. When patients are injured, expert review is called upon and often concludes that airway management provided by the anaesthetists was substandard. Many training programmes do not offer their trainees structured or organised teaching in airway management and many trainees probably enter practice with limited skills to deal with difficult airways. The literature on the management of the difficult airway in anaesthesia practice (especially as it relates to new technology and salvage strategies) is expanding rapidly. New technologies and practised response algorithms may be helpful in the management of the difficult airway, reducing the potential for adverse patient outcomes. Specialist societies and national interest groups can play an important role by critically reviewing and then applying the evidence base to generate clinical practice guidelines. The recommendations contained in such guidelines should be based on the most current evidence and they should be reviewed regularly for their content and continued relevance.

Evidence for benefit vs novelty in new intubation equipment

A myriad of new intubation equipment has been introduced commercially since the appearance of Macintosh/Miller blades in the 1940s. We review the role of devices that are relevant to current clinical practice based on their presence in the scientific literature. The comparative performance of new vs traditional direct laryngoscopes, their complications, their use in awake intubation techniques and the prediction of unsuccessful intubation with new devices are reviewed. Manikin studies are of limited value in this area. We conclude that in both predicted and unpredicted difficult or failed intubation, carefully selected new intubation equipment has a high success rate for tracheal intubation. Ideally, such devices should be available in all settings where tracheal intubation is performed. Most importantly, experience and competence with any of the new devices are critical for their successful use in any clinical setting.

Equipment to manage a difficult airway during anaesthesia

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

Advances in laryngoscopy: rigid indirect laryngoscopy

There is a growing body of evidence to support the use of rigid indirect laryngoscopy or 'video' laryngoscopy for tracheal intubation. We summarise some of the key issues, comparing rigid indirect laryngoscopy with direct conventional laryngoscopy.

Practice Patterns for Predicted Difficult Airway Management and access to Airway Equipment by Anaesthetists in Queensland, Australia

A postal survey was conducted to investigate difficult airway management, training and equipment availability among Fellows of the Australian and New Zealand College of Anaesthetists in Queensland. The survey aimed to determine practise patterns for predicted difficult airways and investigate equipment availability.

Participants were asked to nominate an induction method, intubation method and airway adjunct for each of the five difficult airway scenarios. The cases consisted of one elective and four emergency scenarios. Availability of difficult airway devices in their institution was also assessed, as well as demographics of practice and airway-related maintenance of professional standards participation.

There were 454 surveys distributed and 250 returned (response rate 55%). Direct laryngoscopy and flexible fibreoptic intubation were the most commonly selected techniques for all five cases. Difficult intubation trolleys were available to 98% of responders. Certain types of equipment (such as fibreoptic bronchoscopes and cricothyroidotomy kits) were available less frequently in private institutions. We recommend a standardisation of difficult airway management equipment and an on-going training program to provide support for anaesthetists in all locations.