|Year : 2008 | Volume
| Issue : 1 | Page : 51
Difficult Airway Management Methods:A Survey in Medical Colleges in India
BM Sahay1, Sudha Jain2, Sucheta Tidke2, PS Dhande2, B Premendran3, Sanjot Dahake4
1 Professor, HOD, Mahatma Gandhi Institute of medical Sciences, Sewagram - 442 102, Wardha, Maharashtra State., India
2 Professor, Mahatma Gandhi Institute of medical Sciences, Sewagram - 442 102, Wardha, Maharashtra State., India
3 Lecturer, Mahatma Gandhi Institute of medical Sciences, Sewagram - 442 102, Wardha, Maharashtra State., India
4 Reader, Mahatma Gandhi Institute of medical Sciences, Sewagram - 442 102, Wardha, Maharashtra State., India
|Date of Acceptance||25-Dec-2007|
|Date of Web Publication||19-Mar-2010|
B M Sahay
30 Pioneer Residency Park, Somalwada, Nagpur - 440 025.
Presence of appropriate equipment and actual procedure employed, greatly affect the outcome in Difficult Airway situation. Medical Colleges being torchbearers in this, have been studied. Consultant presence during intubation in 54% Medical Colleges is commendable. Gum Elastic Bougie is rejected as first choice option by 71% Medical Colleges, though 88% Medical Colleges have mentioned Metal or PVC stylets as first choice options.
Blind Nasal Intubation at 33% is the highest 2 nd choice option. The Fibreoptic Bronchoscope and Intubating Laryngeal Mask Airway at 29% and 17% respectively, obtain the third highest choice option.
67% Medical Colleges postpone the difficult airway case for investigations. It facilitates planning and preparation. Planned tracheostomy at combined 4 th and 3 rd choice option of 42% indicates handling of more complicated cases. Flexible fibreoptic stylets and Glidescope are not in the running. Development of low skill procedures for difficult airway is yet to catch up, as does that for invasive airway devices.
We believe that this survey is the first such study carried out in Medical Colleges in India.
Keywords: Difficult Airway Management, Survey.
|How to cite this article:|
Sahay B M, Jain S, Tidke S, Dhande P S, Premendran B, Dahake S. Difficult Airway Management Methods:A Survey in Medical Colleges in India. Indian J Anaesth 2008;52:51
|How to cite this URL:|
Sahay B M, Jain S, Tidke S, Dhande P S, Premendran B, Dahake S. Difficult Airway Management Methods:A Survey in Medical Colleges in India. Indian J Anaesth [serial online] 2008 [cited 2013 Jun 19];52:51. Available from: http://www.ijaweb.org/text.asp?2008/52/1/51/60598
| Introduction|| |
In claims for negligence involving failed airway, the anaesthetic practice and its conduct at the time of the event must be justifiable. The Medical Colleges/ Institutes of Medical Science (MCs) bear predominant responsibility in the endeavor to train, and subsequently assess the so trained post graduate student for higher appointments.
Our earlier survey  assessed the equipments angle of the Difficult Airway Management (DAM), through a National survey involving the MCs. The aim of the present survey is to study the conduct, and the practice aspects, of Difficult Airway Management Methods in the MCs in India, through answers to 6 simple questions, because eventually such surveys result in formulation of National Guidelines. We are not aware of any such survey carried out in MCs in India previously.
| Methods|| |
The Handbook on Medical Education 2003, published by Association of Indian Universities, New-Delhi, had provided the list of 182 MCs. A questionnaire and a subsequent reminder, had secured participation of 40 departments of Anaesthesiology from these MCs.
These 40 MCs were mailed a second questionnaire dated 20:06:2005, containing 6 simple questions on managing Difficult Airway (DA) situations. Self-addressed, stamped envelopes were enclosed to send them back duly filled-in. The answers to questions were to be marked appropriately.
The sixth question had seven subquestions. Answering these, and marking the order of preference was anticipated. Another questionnaire with only the sixth question was sent to those departments where order of preference was not given. The survey stood closed four months later on 20:10:2005, without recourse to any reminder.
| Results|| |
Of the 40 MCs out of 182, who were sent the 2nd questionnaire, 24(13%) returned it duly filled-in.
The full questionnaire comprising 6 simple questions and the seven subquestions to the sixth question, is shown in [Table 1].
Of the 6 questions, 5 are included in [Table 2]. The method employed by MCs is shown in percentage value for first two questions. The answer to the remaining three questions being Yes or No, are shown as percentage values for Yes or No in the same table.
A majority of MCs i.e. 62% will allow 2 attempts for intubation to the residents, while 21% will allow one attempt, and 17% will allow three attempts to the residents. To the Consultant who takes-over, majority i.e. 75% MCs will allow three attempts, 17% MCs will allow 2 attempts, and 8% will allow them only one attempt.
A consultant is always present during intubation in 54% MCs, but not so in 46% of them. When DAM situation with failure is encountered, 67% MCs postpone the operation that day for proper investigations. Gum Elastic Bougie (GEB) to rail-road a tracheal tube on it is not the first choice in 71% MCs.
The seven subquestions in the sixth question, regarding use of particular method or equipment in DA situation, had to be answered in descending order from 1 st to 7 th choice. They are presented as percentage value in [Table 3].
Metal or PVC stylet was the 1st choice option in 88% MCs. The Intubating Laryngeal Mask Airway (ILMA) or the Fibre Optic Bronchoscope (FOB) were the 1st choice option in 8% MCs each.
Blind Nasal Intubation (BNI) was preferred as 2nd choice in DA situations by as many as 33% MCs, well above the 21% of Lighted Stylet, or 17% of the Retrograde Intubation. As many as 75% and 67% MCs respectively, failed to indicate any choice for either of them.
The 3rd choice option in DA situations was fairly closely divided at 17%, 29% and 17% MCs between ILMA, FOB, and Planned Tracheostomy respectively. However, Planned Tracheostomy was preferred as 4th choice option by 25% MCs, well above the other methods in the 4 th choice option.
The 5 th , 6 th ,and 7 th choice options have nothing of note. The highest figure of 8% MCs in 5 th and 6 th choice options each is for FOB, Planned Tracheostomy, and Retrograde Intubation respectively. Planned Tracheostomy is 7th choice option for 13% MCs.
As many as 67%, 38%, and 29% MCs indicate No-choice option for the use of ILMA, FOB, and Planned Tracheostomy, respectively, leaving these subquestions unattempted.
Statistical application was not possible because some of the responses were in single digits and numbering less than 5.
| Discussion|| |
In 1881 Lyman Stated "Death by Suffocation may occur as a result of great negligence or great ignorance" . The premier equipment, then available, comprised Jawprysers to pry open the clenched teeth, and the Tongue Forceps to apply traction by holding the tip of the tongue.
The variations in pharyngeal anatomy and the physiological dynamics of oropharynx continue to be revealed, and are understood incompletely  , despite two ASA Guidelines , flowcharts and algorithms  .
With anteriorly placed larynx, the thyro-epiglottic ligaments make the epiglottis less vertical. The median and the lateral glossoepiglottic ligaments pull the base of the tongue into hypopharynx, making the exposure of the glottis very difficult  .
A more cephalad tongue appears large compared to the size of pharyngeal space. Mandibular defects like micrognathia, or a short ramus reduce the available mandibular space. The tongue fails to be accommodated in this shortened space when laryngoscopy tries to bring the pharyngeal, laryngeal, and the oral axes in one line for intubation  . The widely used Mallampati  , and Cormack-Lehane  assessments derive from these factors.
The thyro-mental distance below 6 cm is associated with difficult laryngoscopy and difficult airway , . All these are further compounded by a short atlanto-occipital gap below 5 mm, which restricts the otherwise available 35° of extension of the head on the neck at this joint ,. All such measurements and constant research has contributed towards the enunciation of the LEMON Law for quick airway assessment in emergency  . It is beyond the scope of this article to discuss it.
The understanding of physiological dynamics have acquired clearer definitions from paediatric anaesthesia. The pharyngeal airway has no rigid bony structure, except soft tissues as its walls. The mechanical support to its patency is from sustained muscle tension, and the synchronous contractions of the pharyngeal dilator muscles along with those of the diaphragm.
During unconsciousness these muscles relax, the pharyngeal airway collapses, the velopharynx relaxes, the mandible is displaced posteriorly, so also is the base of the tongue. With this the pharyngeal closure occurs. The mucosal adhesion force from the opposing mucous surfaces then starts acting to prevent the opening of the pharyngeal air passage  .
The 1.5 to 3.8% incidence of difficult intubation in routine anaesthesia, and of 3 to 5.3% in emergency , may appear low, but is frightening and could be catastrophic when faced single handedly. Ensuring safety could comprise 3 angles i.e. the presence of DAM equipments, the Training for DAM situations, and On-the-spot action for DA situation.
Anaesthesiology Departments in MCs are the torchbearers in this exercise. Therefore, only 13% (24) MCs returning the questionnaire, forced us to drop the word "National" From the survey. Elsewhere such surveys attract more than 70% participation  .
The Difficult Airway, Difficult Mask Ventilation, and Difficult Laryngoscopy, have clear definitions from the ASA Task Force  . Their definition of Difficult Endotracheal Intubation as failure to intubate in 3 attempts or more than 10min with conventional laryngoscopy is valid, and is the basis of this second questionnaire. For these reasons the first 3 questions out of the 6, are personnel oriented.
Our survey allows 2 attempts to residents by 62% MCs and 3 attempts to consultant by 75% MCs. Thus at least 62% patients with DA would have had 5 attempts at intubation, assuming that counting of number of attempts is correct.
Here caution is needed because with repeated attempts and resultant trauma to the soft tissues, the inflation of lungs becomes progressively difficult to the point of abolishment through deterioration of the airway  . Proper oxygenation is emphasized.
The finding of a consultant presence during intubation in 54% MCs is commendable and needs enhancement to cent percent. Residents in USA are supervised both at induction of anaesthesia and towards the end, but in U.K. they are on their own early during their training .
The universal presence of metal or PVC stylets which also include the Schroeder type, accounts for its 88% first choice option by MCs. Negligible cost, being handy, portable, and damage resistant, may be factors augmenting the first choice position for these stylets.
Of the sixteen optical stylets comprising flexible fibreoptic imaging elements seven are commercially available  . The video optical intubation stylet, the Visualized endo tracheal tube, the Stylet scope, the Shikani seeing stylet, and the Bonfils fibrescope stylet are better known. They must use 10,000 pixels or more to be effective, the angles of view of the lenses must range from 50° to 100° , and the lenses must have focal length of 550 mm. Obviously they have not penetrated the DAM scenario in the MCs.
The Gum Elastic Bougie (GEB) is a first choice option in countries like U.K. or Canada  , not so in USA 21. The proponents of GEB are quite candid : Only a view of epiglottis is required behind which the tip of GEB is quickly slipped, click of tracheal rings or resistance to advancement after insertion of 45 cms of the 60 cms bougie length help identification of correct placement, and the tube rail-roaded over it into the trachea. This advocacy remains the same in the year 2002  .
Meant for single use, non-autoclavable, and high cost, may explain its rejection as first choice equipment by 71% of our MCs, though 29% MCs do keep GEB as first choice option. A survey in U.K. found GEB facilitating successful tracheal intubation in 199 out of 200 DA situations, the lone exception where it was abandoned being that of a pharyngeal tumour  .
As many as 67% MCs would postpone the operation on that day for proper investigations in cases of unanticipated DA situation. This approach justifies the teaching and research-oriented character of the MCs.
The seven subquestions in the 6th question brought to fore the eighth column of "O-Choice or No-Choice", interpreted as avoiding the proposed technique or the equipment altogether, or its absence in the available DAM armamentarium. The 8% MCs indicating No-Choice for metal or PVC stylets may indicate their move towards newer options. Similarly 75% MCs showing No-choice for simple, sturdy and rather cheap, Lighted stylet, could explain deficient product penetration. The flexible fibreoptic stylets are not even in the running.
The Blind Nasal Intubation as the largest second choice by 33% MCs may be a carry-over from the decades gone-by. It is probably easier described than practiced and the danger of repeated attempts producing narrowing of the airway is ever present. Addition of epistaxis to DA situation can produce severe hypoxia and preclude the use of equipments like FOB justifying the advice "Look before you leap"  . These reasons may also explain the 46% No-choice for BNI by MCs.
The DAM journey, starting with Jaw-prysers and Tongue Forceps, accommodated the Hewitt airway in 1908, and the Guedel Airway in 1933. A dichotomy now divides it into two clear zones. The first is the zone of airways 2 , the Guedel airway, the Nasopharyngeal airway, the Laryngeal Mask Airway, and the specifically designed Intubating airway. The second zone comprises a multiplicity of necessary instruments and equipments for DAM purposes.
The ILMA can provide blind intubation, or fibreoptic guided intubation through its lumen  . Concentrating on it, our survey found its acceptance by only 17% MCs that too as third choice, well behind the procedures mentioned in preceding paragraphs. Of greater importance is the fact that it has 0-choice by 67% MCs.
This is not unexpected. Its availability with MCs is low  , probably cost based. It has a steep learning curve and requires special maneuvers like Chandy Manoeuver for laryngeal approximation prior to intubation. The body of ILMA has rigid and fixed length due to which the fibreoptic positioning offered by ILMA may be inferior to that by cLMA  . Attempts are now being directed towards using cLMA rather than ILMA, along with specially developed catheters like Aintree Intubation Catheter (AIC) mounted on the FOB for intubation.
In due course of time the fraternity may try to find more such ways to utilize cLMA as conduit for FOB and other devices. The cLMA has multiple stations on the DA algorithm of the ASA Task Force  . Millions of them are providing conventional general anaesthesia as well. With its increasing use complications have also surfaced including brain injury and death  , though reports of pulmonary aspiration have been there from 1990 onwards  .
The FOB by itself, could have been seen as the ultimate in DA situations. It probably is not. It requires good training. Besides, the induction of general anaesthesia makes epiglottis, tongue, and soft palate to fall back on posterior pharyngeal wall, leaving little space for maneuvering its tip. Apart from this, at no time the tip of the advancing tube is visible to the operator. Failure to intubate the trachea over FOB have been described from 1983 onwards .
In our survey, the highest percentage - 29% MCs have put FOB as only third choice, while for just 8% MCs it is the first choice option. A recent meta analysis on studies for difficulty in advancing a tracheal tube on FOB showed it to lie between 0 to 90%  . An imaginary line drawn straight up from 50% mark on abscissa, would pass through 54% of the study lines some where in their [Figure 1], apparently indicating a 50% incidence of this difficulty. Further, as many as 21% studies actually lie beyond the 50% mark to the right side, making the incidence of difficulty with FOB intubation still higher.
Impinging of the tube on the arytenoid cartilage, mainly the right side, and slipping into the esophageal inlet are predominant causes. Other factors could be use of right nostril, cricoid pressure, jaw thrust, upper airway distortion by tumor, FOB passing through Murphy's eye, and part of FOB curling in the esophagus , . FOB causing gastric rupture has been reported .
The difficulties encountered with FOB alone, is diversifying the research. Aintree intubating catheter 24 and Glidescope  are some examples. Of the 13% MCs indicating first choice for FOB, one was emphatic "There will be no postponement, fibreoptic intubation will be done and the case proceeded with". The survey would hope that to be the bottomline, but it will not be.
The 67% O-choice for invasive airway management methods comprising Cricothyroidostomy kit, Percutaneous Tracheostomy kit, or even a Pre-assembled Crico-thyroidostomy set, is a big disappointment for the survey. It has life saving importance  , and must be a part of DAM training schedules on matching manikins.
Emergent or Planned Surgical Airway or Tracheostomy constitutes the other part of invasive airway management. The literature routinely emphasizes that it must be at hand, but is silent on its actual contemporary use. Its highest percentage is attracted at 4 th choice by 25% MCs. Combining this with the figure of 3 rd choice, shows a total of 42% MCs indicating surgical airway as fourth or third choice. Cost effective and being easily available, it is also indicated in presence of oral or upper airway tumors virtually blocking the airway, thus making use of other methods impossible. Being higher referral centers, the MCs will have to handle more such cases than others.
The view of airway management, then is complex. No single piece of DAM equipment or procedure can be said to be an end in itself. While one side of the Atlantic tries to show mastery over FOB and ILMA, the other side is explicitly clear "Most British anaesthetists donot possess this skill .
Where does that leave us? The 88% first choice option for metal or PVC stylets, the 33% second choice option for BNI, and 42% combined fourth and third choice option for surgical airway, would tend to indicate nonavailability and/ nonadoption of more recent technology, equipments, or procedures in the MCs.
The airway and its management will continue to be researched and written about. Will there be emergence of an ultrathin fibreoptic device, the distal end of which will be stationed just prior to the tip of the tracheal tube, the proximal end at the top of the tube, and it will have facility to move the tip of the tube anteriorly or posteriorly with just right index finger, while in the left hand the versatile Mackintosh laryngoscope works conventionally?
Perhaps the Glidescope system, offering a view of the glottis, in cases where mouth can be opened and the Glidescope can be advanced, may be a move in that direction  . So also, the very high skilled fibreoptic intubation having difficult learning curve and needing proper training and continuing experience, has already initiated thoughts of "Low-skill" procedures  through simultaneous use of more convenient items like cLMA and AIC along with it.
Some limitations in the survey are inevitable. Participation by MCs was low. A reminder not bearing result during earlier survey, was not resorted-to again. The answer to sixth question should not have been originally allied to that of the fifth question. Question on the use of cLMA, on failure of both the resident and the consultant, was absent by design. Morbid obesity not being encountered on regular basis by many of our anaesthetists, led to exclusion of question on it from the survey.
To conclude, the airway management and its training, as is evident from this survey in MCs, has some distance to go. The number of attempts at intubation, to the residents, or to the consultants, appears justified. The consultant presence at intubation should be enhanced to 100%. The heavy reliance on Metal or PVC Stylet raises concern, as would combined 54% second-third-fourth choice for Blind nasal intubation which indicates continuing reliance on methods of years gone-by.
There is lag in adoption and application of newer technology as reflected by only 16% first and second choice for FOB, or 75% No-choice for a simple alternative like the Lighted stylet. Whether poor product penetration, or cost consideration, are the contributing factor, is difficult to comment upon.
Preference for planned tracheostomy indicates acceptance of many such difficult airway cases refused operation and anaesthetic elsewhere. Very small sample size participation does not allow suggestions to be made. A few more such surveys, with better participation, though, may help with formulation of ISA Guidelines for difficult airway management.
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[Table 1], [Table 2], [Table 3]