|Year : 2008 | Volume
| Issue : 3 | Page : 317-320
Paraglossal Straight Blade Intubation Technique-an Old Technique Revisited in Difficult Intubations: A Series of 5 Cases
Sanjay Agrawal, Veena Asthana, Ravi Meher, DK Singh
Assistant Professor, Department of Anesthesia and ENT, Himalayan Institute of Medical Sciences, Jollygrant, Dehradun, Uttarakhand, India
|Date of Acceptance||02-Apr-2008|
|Date of Web Publication||19-Mar-2010|
Assistant Professor, Anaesthesia, Himalayan Institute of Medical Sciences, Jollygrant, Dehradun
Source of Support: None, Conflict of Interest: None
We as anaesthesiologist at times encounter patients with mandibular dystocias, and oral/oropharyngeal lesions for surgical management. Such patients pose a challenge for airway management and intubation and at times procedure may end with tracheostomy. The Macintosh curved blade laryngoscopy is gold standard for intubation. This technique may be technically flawed in conditions like vallecular cyst, tonsillar growth, mandibular dystocias and hemifacial microsmia. However the experience of otolaryngologists to visualize the glottis using a straight blade direct laryngoscope (Jackson type) in cases where anaesthesiologist fails, prompted us to use straight blade laryngoscope (Miller's) for intubation. Here we describe, review and discuss an alternative technique of paraglossal straight blade intubation. We have tried this technique in five patients of difficult intubation and were able to avoid emergency cricothyrotomy and tracheostomy.
Keywords: Paraglossal straight blade, Intubation, Vallecular cyst, Tonsillar growth, Mandibular dystocias and Hemifacial microsmia.
|How to cite this article:|
Agrawal S, Asthana V, Meher R, Singh D K. Paraglossal Straight Blade Intubation Technique-an Old Technique Revisited in Difficult Intubations: A Series of 5 Cases. Indian J Anaesth 2008;52:317-20
|How to cite this URL:|
Agrawal S, Asthana V, Meher R, Singh D K. Paraglossal Straight Blade Intubation Technique-an Old Technique Revisited in Difficult Intubations: A Series of 5 Cases. Indian J Anaesth [serial online] 2008 [cited 2020 Jun 3];52:317-20. Available from: http://www.ijaweb.org/text.asp?2008/52/3/317/60641
| Introduction|| |
Patients with mandibular dystocias and oral/ oropharyngeal lesions posted for various surgeries, pose problem to an anaesthesiologist with regards to airway management. Causes for difficult intubation in these may be due to the lesions occupying the path of intubation, relative macroglossia as a consequence of skeletal abnormalities ,,, reducing the space available for manipulation and insertion of endotracheal tube. The ability of paraglossal straight blade technique to give reliable view of larynx is confirmed by experience of E.N.T. surgeons who rarely fail to visualize the vocal cords using straight blade. In anaesthetic practice, use of E.N.T. type straight blade has enabled good visualization of larynx where laryngoscopy with conventional blade has been unsuccessful  .Here we present the data of five cases of difficult intubations where alternative intubation technique of paraglossal straight blade technique was tried and found to be successful for intubation. This technique is especially useful for management of difficult airway at places lacking advance airway management gadgets.
| Case report|| |
[Table 1] shows the profile of five patients taken up for various surgeries. All the patients were on preoperative assessment declared as difficult intubations. Since fibreoptic bronchoscope was not available at the time, alternate airway management instruments such as LMA, cricothyroid puncture needle and standby surgeons to perform emergency tracheostomy were at hand.
The patients were not premedicated in the ward. On shifting to the operating room (OR), glycopyrrolate 0.2 mg was given intravenously.
Inhalational induction of anaesthesia was done with incremental concentration of halothane in 66%nitrous oxide and oxygen .Care was taken that spontaneous ventilation was maintained at all time .When sufficient depth of anaesthesia was attained a small bolus of propofol(1mg.kg -1 )was given before attempting laryngoscopy. Initially Macintosh laryngoscope was tried by an experienced anaesthesiologist of greater than 5 years of experience. As the attempts to visualize the larynx were unsuccessful, paraglossal straight blade technique was tried by the same anaesthesiologist using appropriate sized Miller blade, introducing the blade from right hand side of the mouth. In all the cases Cormack and Lehanne intubation grade improved and intubation was successful.Cormack and Lehane grade as visualized during intubation by different blades were designated as Mackintosh view(Mackintosh blade) and Paraglossal view(Miller blade, paraglossal approach). In two patients two attempts were needed for successful intubation.
| Description of paraglossal technique|| |
In basic paraglossal technique  size 3 or 4 Miller's blade is passed from right corner of mouth, along the groove between tongue and tonsil using leftward and anterior pressure to displace the tongue to the left of laryngoscope and to maintain tongue in this position at all time. Blade is advanced; epiglottis visualized and tip of blade passed posterior to epiglottis. The blade is lifted anteriorly thus elevating the epiglottis directly and visualizing the glottic opening. If a good view is not achieved the blade should be kept lateral to the incisor and head rotated to left. In comparison to Macintosh technique this approach gives a better view of larynx at an expense of less space to manipulate the tracheal tube. As a consequence an assistant retracts the corner of the mouth and improve the maneuverability of the tube using a stylet.
| Discussion|| |
Difficult intubation is defined, as a condition where conventionally trained anaesthesiologist is unable to intubate or ventilate the patient after 3 attempts. The presence of difficult intubations is a common finding in patients with oral/ pharyngeal lesions.
The cases with anticipated difficult intubations are usually managed along the awake limb of difficult airway algorithm  . However unanticipated difficult intubations may be encountered usually after inducing anaesthesia. Various approaches have been evolved for dealing with these situations. Introduction of LMA by Archie J Brain  in 1981 has revolutionized unanticipated airway management, as this device is successful in maintaining the airway& ventilation even if intubation is not possible.
The use of Macintosh laryngoscope blade is a gold standard for intubation and is the preference of many of conventionally trained anaesthesiologists. The technique is usually atraumatic, gives a good view of glottis and its ease of use has made it a preferred technique. The high success rate leads to complacency regarding the role of alterative laryngoscopy and techniques; with consequent failure to develop skill in their use ,, .
The use of fibreoptic intubations has changed the scenario in cases of difficult intubation , . However its use is precluded by high cost and expertise required for its use. Its use in emergency condition is hampered due to presence of blood/mucus/secretions. Use of fibre optic bronchoscope through LMA, ILMA for intubation has greatly increased the efficacy of this procedure for successful intubation. Due to the above cited problems, an alterative technique of intubation using more than one type of laryngoscope& blades have been recommended by many authorities for increasing the chances of success. Hex Venn  described the successful use of rigid bronchoscope inserted from right side of mouth in a grade 4 (Cormack& Lehanne classification) laryngoscopy patients when other techniques have failed to achieve tracheal intubation and speculated that use of straight laryngoscope blade from side of mouth could improve glottic visualization in such patient.
The advantage of visualsation using Miller's blade is better view but at an expense of limited space of manipulation of tracheal tubes. As a consequence use of stylet/bougie with retraction of corner of the mouth by assistant improves maneuverability of tracheal tube.
The causes of difficult intubation are multifold, ranging from inadequate mouth opening, limited extension of head over neck, TM joint pathology, retrognathia, micrognathia, relative macroglossia, anterior larynx or posterior displacement of epiglottis obscuring the glottic view. Other problems of intubation associated with large oral and oropharyngeal lesions are:
Disadvantage of Macintosh blade in such cases may be due to the following causes:
- Direct laryngoscopy usually fails to expose epi-lottis as lesions are large, fragile and tend to bleed.
- Some swelling can impinge against epiglottis, displacing it posteriorly. This makes mobilization of epiglottis difficult with usual laryngoscopy .
- Use of neuromuscular block for intubation leads to pharyngeal muscles relaxation causing further posterior movement of tongue and epiglottis .
- Multiple direct laryngoscopic attempts can cause edema and/or bleeding with subsequent difficult ventilation.
The cause of improved view by paraglossal straight blade technique is due to contribution from both the paraglossal approach and the straight blade laryngoscope. The actual mechanism for improved visualization is due to reduction of soft tissue compression (central component of line of sight) and lowering of proximal end of line of sight , . Moreover the straight blade overcomes the problem of intrusion of curvature of Macintosh blade into the line of sight. Improved view by extension of head is possible with use of straight blade but not with curved blade.
- The contribution of soft tissue of oral cavity may play an important role in difficult intubation. Relative macroglossia usually as a consequence of skeletal abnormalities may be a major problem in most cases of difficult intubation .
- In cases where the volume of oral/pharyngeal cavity is less and size of tongue are relative large leads to difficult airway thus leaving the anaesthesiologist to deal with secondary effects of soft tissue.
- Insuch cases use of Macintosh blade not only displaces the tongue to left but also compresses the residual volume distally to 'pear drop' shape so that epiglottis is displaced posterior towards pharyngeal wall and thus obstructing the glottic view. Thus this technique may be fundamentally flawed in presence of absolute or relative macroglossia  .
The ability of paraglossal straight blade technique to give reliable view of larynx is confirmed by experience of E.N.T. surgeons who rarely fail to visualize the vocal cords using straight blade. Normally the direct laryngoscope (Jackson type) is held close to center of mouth. They normally move tongue to left of laryngoscope. In anaesthetic practice use of E.N.T. type straight blade has enabled good visualization of larynx where laryngoscopy with conventional blade has been unsuccessful.
Thus in conclusion this technique leads to successful intubations in cases where Macintosh blade fails. The result in literature is encouraging and raises a question as to why this technique is not practiced regularly? This technique warrants practice for its use with confidence when laryngoscopy proves difficult with other techniques.
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