Laryngeal Mask AirwayHai YuDepartment of AnesthesiologyWest China HospitalSichuan UniversityIntroductionwThe LMA was invented by Dr. Archie Brain at the London Hospital, Whitechapel in 1981wUK(1988) , US (1991)wThe LMA consists of two parts:The maskThe tubewThe LMA has proven to be very effective in the management of airway crisisIntroduction continuedwThe LMA design: Provides an “oval seal around the laryngeal inlet” once the LMA is inserted and the cuff inflated. Once inserted, it lies at the crossroads of the digestive and respiratory tracts.Indications for theuse of the LMAwSituations involving a difficult mask fit.wMay be used as a back-up device where endotracheal intubation is not successful.wMay be used as a “second-last-ditch” airway where a surgical airway is the only remaining option. Contraindicationsof the LMAwGreater than 14 to 16 weeks pregnantwPatients with multiple or massive injurywMassive thoracic injurywMassive maxillofacial traumawPatients at risk of aspirationwNOTE: Not all contraindications are absolute Side-Effects of the LMAwThroat sorenesswDryness of the throat and/or mucosa wSide effects due to improper placement vary based on the nature of the placementEquipment for LMA InsertionwBody Substance Isolation equipmentwAppropriate size LMA wSyringe with appropriate volume for LMA cuff inflationwWater soluble lubricantwVentilation equipmentwStethoscopewTape or other device(s) to secure LMAPreparation of the LMA for InsertionwStep 1: Size selectionwStep 2: Examination of the LMAwStep 3: Check deflation and inflation of the cuffwStep 4: Lubrication of the LMAwStep 5: Position the AirwayStep 1: Size SelectionwVerify that the size of the LMA is correct for the patientwRecommended Size guidelines:Size 1: under 5 kgSize 1.5: 5 to 10 kgSize 2: 10 to 20 kgSize 2.5: 20 to 30 kgSize 3: 30 kg to small adultSize 4: adultSize 5: Large adult/poor seal with size 4Step 2: Examination of the LMAwVisually inspect the LMA cuff for tears or other abnormalitieswInspect the tube to ensure that it is free of blockage or loose particleswDeflate the cuff to ensure that it will maintain a vacuumwInflate the cuff to ensure that it does not leakTEST: VISUAL INSPECTIONStep 3: Deflation and Inflation of the LMAStep 1: LeakagewDeflate the cuff so that the cuff walls are tightly flattened against each other. Do not use the LMA airway if the cuff walls reinflate immediately and spontaneously, even if only slightly. wInflate the cuff with air from a complete vacuum as shown in the table below.wTest Cuff Inflation Volumes:Size 1: 6 mlSize 1.5: 10 mlSize 2: 15 mlSize 2.5: 21 mlSize 3: 30 mlSize 4: 45 mlSize 5: 60 mlSize 6: 75 mlStep 2: Herniation Step 4: Lubricationof the LMAwUse a water soluble lubricant to lubricate the LMAwOnly lubricate the LMA just prior to insertionwLubricate the back of the mask thoroughly Important Notice: wAvoid excessive amounts of lubricanton the anterior surface of the cuffin the bowl of the mask. wInhalation of the lubricant following placement may result in coughing or obstruction.wLubrication of the mask should avoid the use of local anesthetics in order to preserve protective reflexes against aspiration.Step 5: Positioningof the AirwaywExtend the head and flex the neckwAvoid LMA fold over:Assistant pulls the lower jaw downwards.Visualize the posterior oral airway. Ensure that the LMA is not folding over in the oral cavity as it is inserted.LMAInsertionTechniqueLMA Insertion Step 1wGrasp the LMA by the tube, holding it like a pen as near as possible to the mask end.wPlace the tip of the LMA against the inner surface of the patients upper teethLMA Insertion Step 2wUnder direct vision:Press the mask tip upwards against the hard palate to flatten it out. Using the index finger, keep pressing upwards as you advance the mask into the pharynx to ensure the tip remains flattened and avoids the tongue.LMA Insertion Step 3wKeep the neck flexed and head extended: Press the mask into the posterior pharyngeal wall using the index finger.LMA Insertion Step 4wContinue pushing with your index finger. Guide the mask downward into position.LMA Insertion Step 5wGrasp the tube firmly with the other handthen withdraw your index finger from the pharynx. Press gently downward with your other hand to ensure the mask is fully inserted.LMA Insertion Step 6wInflate the mask with the recommended volume of air.wDo not over-inflate the LMA. wDo not touch the LMA tube while it is being inflated unless the position is obviously unstable.Normally the mask should be allowed to rise up slightly out of the hypopharynx as it is inflated to find its correct position.Verify Placement of the LMAwConnect the LMA to a Bag-Valve Mask device or low pressure ventilatorwVentilate the patient while confirming equal breath sounds over both lungs in all fields and the absence of ventilatory sounds over the epigastriumSecuring the LMAwInsert a bite-block or roll of gauze to prevent occlusion of the tube should the patient bite down.wNow the LMA can be secured utilizing the same techniques as those employed in the securing of an endotracheal tube.Problems with LMA InsertionwFailure to press the deflated mask up against the hard palate or inadequate lubrication or deflation can cause the mask tip to fold back on itself.Problems with LMA InsertionwOnce the mask tip has started to fold over, this may progress, pushing the epiglottis into its down-folded position causing mechanical obstruction Problems with LMA InsertionwIf the mask tip is deflated forward it can push down the epiglottis causing obstructionwIf the mask is inadequately deflated it may eitherpush down the epiglottispenetrate the glottisContraindicationwIn patients at risk of regurgitation - obese, hital hernia, pregnant patient - history of gastric regurgitation, heartburn, ileus - full stomachwIn patients with pathology in pharynxwPatients with low pulmonary compliance or high pulmonary resistance ( 20 cmH20).wWhenever access to patients airway is difficult or ETT cannot readily accomplished (prone, lateral, Jackknife position)SummarywRecent studies suggest that the LMA is an airway device that paramedics “adapt to rapidly”. wParamedics have proven themselves very successful in the placement of the LMA.wThough endotracheal intubation remains the definitive technique for securing an airway in the prehospital setting, it is believed that the LMA may help in a small percentage of patients who prove to be difficult to intubate endotracheally.Types of LMAwLMA-Classic- Classic LMA wLMA-Unique-Unique LMAwLMA-Flexible-Reinforced flexible LMA wLMA-Fastrach-Intubating LMA (ILMA)wLMA-Proseal-Gastric LMAwLMA-CTrach-Vision LMAClassic LMASizes selection with LMAAdvantages and disadvantages of the LMA over face mask during anesthesiaAdvantages and disadvantages of the LMA over tracheal intubation during anesthesiaProblemswAirway leak Positive pressure ventilation ?wRegurgitation Risk of aspiration ?wGastric insufflationwFailed insertion wPharyngeal /laryngeal traumawNerve palsieswLaryngospasm / bronchospasmLMA- Positive Pressure VentilationDevitt JH et al; Anesthesiology 1994; 80:550 Rules for Positive PressurewLargest size of LMA possible wStandard insertion techniquewTidal volume : 6-8 ml/kgwAirway pressure : 15-20 cmH20wInflate to only 60 cm H2O intracuff pressurewAuscultation of neckwReverse nm block while still deepwRemoval only when fully awakeAirway Pressure in LMA & ETT Berry A et al Anesthesiology 1999: 90;395-7Aspiration Related to LMAwBrimacombe & Berry (1995); J Clin A 7: 297 - LMA Meta-analysis; 3/12,901 - ETT: 0.026% (Warner MA et al; A 1993 : 78: 65-62) wCho DK et al; KJA1997; 32: 377-83- 2 hr, PPV, methylene blue & pH 4 (GE reflux ) - ETT : LMA 2/49 : 3/41 (only in removal phase)w ASA refresher course (1999) - 20 cases/ 100 million, risk factors, fully recoveredLMA-UniqueFlexible Reinforced LMAwAdenotonsillectomy (William PJ et al; BJA 1993; 70:30)wIntranasal surgery (Webster AC et al; AA 1999; 88:421) - safe, stable protected airway during anesthesia - smoother emergence from anesthesia than ETTIntubating LMAwA new concept in intubationwDesigned for the difficult airwaywNo head or neck movementwSingle-handed insertionwApproach patient from any anglewPermits ventilation between attemptswSize: No. 3, 4, 5(LMA-FastrachTM)Features of the LMA-FastrachPREPARATION OF THE LMA-FASTRACHLMA-Fastrach being removed from LMA Cuff-Deflator.Lubricate only the posterior surface of the deflated mask tip with a water soluble lubricant.LMA-FASTRACH SELECTIONMAXIMUM CUFF INFLATION VOLUMESLMA-FASTRACH with ETTLMA-FASTRACH Insertion TechniqueLMA-FASTRACH Insertion TechniqueLMA-FASTRACH Insertion TechniqueGastric LMALMA-Proseal Insertion TechniqueLMA ProSeal Cuff-Deflator Instructions for Use LMA-Proseal Insertion TechniqueLMA-CTrachLMA-CTrach Insertion TechniqueDifficult airway algorithm with LMAThank you!For better airway management