Laryngeal mask airway (LMA) is often performed for airway management. Correct placement of LMA can prevent severe leaks and even obstruction of the airway. Insertion under laryngoscope guidance has been used to achieve the ideal positioning of the LMA. Efficacy of LMA insertion by laryngoscope can be evaluated with cheap, safe, and easy to use method. This case series evaluates LMA insertion with McGrath video laryngoscope and Macintosh laryngoscope. We use 20 cases to evaluate oropharyngeal leak pressure, time taken for insertion, hemodynamic after insertion, first attempt insertion, ease of insertion, and adverse airway event after LMA insertion
Keywords: Laryngeal mask, laryngoscope, leak pressure, McGrath, Macintosh
|How to cite this URL:|
Agung Senapathi TG, Surya Panji PA, Herry Yudiskara I G, Pradhana AP. Classic laryngeal mask airway insertion with laryngoscope mcgrath and macintosh: A case series. Bali J Anaesthesiol [Epub ahead of print] [cited 2021 Apr 22]. Available from: https://www.bjoaonline.com/preprintarticle.asp?id=290529
| Introduction|| |
The laryngeal mask airway (LMA) is a common supraglottic device used to maintain the airway in patients undergoing general anesthesia. Although introduced and widely used using a blind insertion approach, LMA can be inserted using laryngoscopy to facilitate better anatomic placement.,,,, Correct LMA position ensures proper ventilation and minimizes airway adverse events during insertion.,,, Recently, oropharyngeal leak pressure (OPLP) is used to evaluate airway protection after LMA insertion.
On LMA insertion, laryngoscope keeps the tongue on the left part of the oral caity, to bring the epiglottis into view., The advantage of using a video laryngoscope such as McGrath for LMA insertion is the presence of a camera through a blade that provides a wide-angle view compared to a standard laryngoscope blade.,,
This case series was to assess the efficacy of classic LMA insertion using McGrath video laryngoscope and Macintosh laryngoscope. The primary outcome of this case series was the OPLP measured by closing the expiratory valve of the circuit at a fixed gas flow rate of 6 L/min and noting the airway pressure at which the gas leaked into the mouth. The primary outcome of this case series was the OPLP.
| Case Report|| |
Twenty patients aged between 16 and 65 years old with American Society of Anesthesiology physical status I–II who underwent general anesthesia with LMA were enrolled in this case series [Table 1].
|Table 1: Evaluation of classic laryngeal mask airway insertion using McGrath video laryngoscope and Macintosh laryngoscope|
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All of the patients received premedication with intravenous midazolam 0.05 mg/kg BW. Patients were monitored using standard monitoring. Anesthesia was induced using propofol 2 mg/kg and fentanyl 2 mcg/kg. After the patient lost consciousness, 2 vol% sevoflurane was administered and mask ventilation was performed for approximately 5 min for adequate depth of anesthesia and muscle relaxation. Lubricated LMA (Teleflex™, Athlone Co. Westmeath, Ireland) was inserted, and selection of the LMA size was based on the bodyweight of the patient. LMA cuff was inflated at 60 cmH2O using a handheld manometer. Anesthesia was then maintained using compressed air, O2, sevoflurane, and fentanyl.
Hemodynamic parameters were recorded at baseline, 1 min after induction, and 1 min after insertion of the LMA. The OPLP was measured using a calibrated aneroid manometer attached to the proximal end of the LMA. After closing the expiratory valve of the circuit at a fixed gas flow rate of 6 L/min, OPLP was detected by audible air leak noise that could be heard over the mouth and manometric stability. To ensure safety, the maximal allowable OPLP was fixed at 30 cmH2O. Time taken for LMA insertion is defined as the duration from the time the anesthesiologist picked up the LMA till the ventilator tubing corrugated attached. Ease of LMA insertion is a subjective assessment of the insertion procedure by grading it as easy, fair, or difficult. Sore throat and blood on LMA after removal were evaluated as an adverse event.
In term of ease at insertion, all anesthesia residents who inserted the LMA with McGrath gave fair opinion, but they gave difficult to fair opinion on using Macintosh. All LMAs were inserted by the first attempt. There was no adverse airway event on our case such as sore throat and blood on LMA.
| Discussion|| |
The correct LMA position will fit against the epiglottic tissues, occupying the hypopharyngeal space and upper esophagus, forming a seal above the glottis instead of within the trachea. Fber-optic use to evaluate LMA insertion provides conflicting results. Ssome researchers suggested that fiber-optic score is not an accurate test to assess the seal of LMA., It was suggested that the actual tightness of the inserted LMA rather than fiber-optic view was an important parameter of adequate airway management., With OPLP values, we can evaluate the quantity of airway seal and it is regarded as the most important value for LMA feasibility of positive pressure ventilation., In this case, we found that OPLP with McGrath was 20–26 mmHg and with Macintosh 18–26 mmHg. Kim et al. and Ozgul et al. reported that the OPLP was higher in the laryngoscope-guided LMA insertion., Video laryngoscope may improve LMA insertion conditions and prevent airway gas leaks, airway obstruction, and impaired gas exchange.
Video laryngoscope provides faster glottis visualization and reduced intubation time than direct laryngoscope. Compared to blind insertion, laryngoscope guided has a longer time on LMA insertion., A systematic review by Lewis et al. found that the proportion of successful first-attempt intubation was better on video laryngoscope. Repeated attempts at inserting LMA increases the probability of airway trauma. We found that classic LMA insertion time with McGrath was 30–39 s and with Macintosh 32–42 s. All of LMA insertion taken by the first attempt and no adverse airway event were recorded.
There were no differences in hemodynamic parameters on blind LMA insertion and laryngoscope-guided LMA insertion., Yokose et al. on a retrospective study found that using a McGrath laryngoscope reduces the incidence of hypertension after tracheal intubation compared to a Macintosh laryngoscope. In our case, the patient's heart rate change 1 min after induction to 1 min after LMA insertion was 10–26 beats/min with McGrath and 10–23 beats/min with Macintosh. Patients' MAP change 1 min after induction to 1 min after LMA insertion was 2.0–19.0 mmHg with McGrath and 3.7–15.3 mmHg with Macintosh.
The ease of LMA insertion is very subjective and depends on experience using a laryngoscope for inserting the LMA. We found that two residents experienced difficulty with LMA insertion using Macintosh laryngoscope, but others gave fair comment.
| Conclusion|| |
Using video laryngoscope as an adjunct in LMA insertion is helpful. Further studies with larger subjects to assess its effectivity is needed in the future.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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Tjokorda Gde Agung Senapathi,
Department of Anesthesiology and Intensive Care. Faculty of Medicine, Udayana University. Jl. PB Sudirman, Denpasar 80232, Bali
Source of Support: None, Conflict of Interest: None