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LMA Classic, Unique, and Classic Excel
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Prior to insertion, carefully inspect the cuff for leaks with the cuff slightly overinflated. Completely deflate the cuff so that it forms a smooth wedge shape. The technique for inserting the LMA-C, LMA-U, and LMA-CE is rather simple (Figure 19-15). Lubricate the posterior surface of the LMA with a water-soluble lubricant. Care must be taken to avoid lubricating the anterior surface of the device, as the gel might obstruct the distal aperture or trickle into the larynx and provoke laryngospasm.7 Avoid using silicone-based lubricants that may degrade the cuff.8 Avoid lubricants containing lidocaine as they may provoke an allergic reaction or decrease laryngeal protective reflexes.8
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Position the patient's head as for ET intubation in the sniffing position. Place the nondominant hand behind the patient's head to stabilize the occiput and slightly flex the neck (Figure 19-15A). Allow the patient's jaw to fall open. An assistant may be required to help open it.
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Insert the LMA into the oral cavity with the aperture facing but not touching the tongue (Figure 19-15A). It is essential that the leading edge of the cuff be smooth, wrinkle-free, and shaped like a wedge. This facilitates passage of the cuff around the posterior pharyngeal curvature and into the hypopharynx while avoiding the epiglottis. Place the index and middle fingers of the dominant hand against the junction between the LMA and the cuff (Figure 19-15B). Advance the LMA in one smooth movement following the curvature of the pharynx until it enters the hypopharynx (Figure 19-15B). The fingers should lie almost horizontally when the LMA is properly positioned.13,14 Grasp and stabilize the airway tube with the nondominant hand, then remove the index and middle fingers of the intubating hand (Figure 19-15C). Slightly advance the LMA further downward until resistance is felt. At this point, it is important to not push further. If difficulty is encountered, a rotational movement of the tube, slight inflation of the cuff, a jaw-thrust maneuver, or, in rare cases, the use of a laryngoscope may be helpful.7
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Inflate the cuff with the recommended volume of air (Figure 19-15D). Do not overinflate the cuff. Inflation usually causes a characteristic outward movement of the airway tube of up to 1.5 cm as the cuff centers itself around the laryngeal inlet. A slight forward movement of both the thyroid and cricoid cartilages will be noted. The longitudinal black line on the shaft of the tube should lie in the midline against the upper lip. Any deviation may indicate the wrong size device was used or misplacement of the cuff and a partial airway obstruction.7 When correctly positioned, the tip of the LMA cuff lies at the base of the hypopharynx against the upper esophageal sphincter, the sides lie in the pyriform fossae, and the upper border of the mask lies at the base of the tongue, pushing it forward.7 Even when grossly malpositioned, the mask may still create a useful airway.8 Secure the LMA like an ET tube.
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Prior to insertion, carefully inspect the cuff for leaks with the cuff slightly overinflated. Completely deflate the cuff so that it forms a smooth wedge shape. The LMA-PS features a cuff deflator, which is a compact, portable instrument for assuring complete removal of air without causing the silicone to wrinkle. Lubricate the posterior surface of the LMA with a water-soluble lubricant. Insert the LMA-PS like that described above for the LMA-C. The only difference is that the fingertip should be pushed into the introducer strap at the rear of the cuff.
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An alternative method of insertion involves a metal introducer. When using the introducer, head and/or neck manipulation may not be required. Place a properly sized introducer into the strap. Fold the tubes around the convex surface of the introducer and fit the proximal end of the airway tube into the matching slot. Insert the LMA-PS into the oral cavity with the aperture facing, but not touching, the tongue. The back of the mask must remain in constant contact with the hard palate. Rotate the LMA-PS inward in one smooth movement following the curvature of the introducer until it enters the hypopharynx and resistance is felt. Grasp and stabilize the airway tube with the nondominant hand. Remove the introducer. Inflate the cuff and secure the LMA-PS. The LMA-PS includes a built-in bite block.
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Prior to insertion, carefully inspect the cuff for leaks with the cuff slightly overinflated. Completely deflate the cuff so that it forms a smooth wedge shape. Lubricate the posterior surface of the LMA-S with a water-soluble lubricant. Position the patient's head in a semi-sniffing position. The neutral position or a full “sniffing” position may preclude proper placement of the LMA-S.
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Insert the LMA-S. Grasp the LMA-S by the connector end. Insert the LMA-S into the oral cavity with the aperture facing, but not touching, the tongue. Briefly rub the mask tip across the palate in order to lubricate the area. Rotate the LMA-S inward in one smooth movement following the curvature of the pharynx until it enters the hypopharynx and resistance is felt. Directing the distal tip toward the right or left side of the throat may facilitate placement. Grasp and stabilize the airway tube with the nondominant hand. Inflate the cuff and secure the LMA.
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The technique for inserting the ILMA is not very different from that for the standard LMA. It involves a one-handed rotational movement in the sagittal plane with the patients head supported to achieve a neutral position.5 The ILMA may be inserted from above the patient's head (like the LMA) or standing to the side of the patient's head. It may be inserted with the right or left hand.
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Prior to insertion, slightly overinflate the cuff and check it for leaks. Completely deflate the cuff. Lubricate the posterior surface of the airway tube and the mask liberally. Grasp the ILMA by its handle. Place the patient in the sniffing position if no contraindications exist. Open the patient's mouth with the nondominant hand. Position the ILMA over the patient with the tip of the mask in the patient's mouth (Figure 19-16A). Slowly insert the mask while the posterior aspect of the mask remains in constant contact with the hard palate. When the entire mask is inside the patient's mouth and against the hard palate, rotate the ILMA inward along the natural curve of the hard palate and pharynx (Figure 19-16B). The airway tube should maintain constant contact with the upper central incisors as the unit is advanced. Stop advancing the unit when resistance is felt. This signifies that the tip of the mask is in the upper esophagus (Figure 19-16B).
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Inflate the cuff with the recommended volume of air (Figure 19-16C). Inflation usually causes a characteristic outward movement of the airway tube, up to 1.5 cm, as the cuff centers itself around the laryngeal inlet. A slight forward movement of the thyroid and cricoid cartilages will be noted. The airway tube should lie in the midline against the upper central incisors. Any deviation may indicate the misplacement of the cuff and a partial airway obstruction. When correctly positioned, the tip of the ILMA cuff lies at the base of the hypopharynx against the upper esophageal sphincter, the sides lie in the pyriform fossae, and the upper border of the mask lies at the base of the tongue, pushing it forward.
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Confirm proper placement of the ILMA. Have an assistant attach a bag-valve device to the proximal end of the airway tube and ventilate the patient. Observe the upper chest rise, auscultate bilateral breath sounds, and observe end-tidal CO2 monitoring to confirm proper placement. An anterior movement, or bulging, of the cricoid and thyroid cartilages during or after cuff inflation also indicates correct positioning of the ILMA.1
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Insert an ET tube. Lubricate the wire-reinforced silicone ET tube (or a standard ET tube) liberally. Insert the silicone ET tube into the ILMA until the transverse black line on its posterior surface is at the proximal end of the airway tube (Figure 19-16D). At this point, the tip of the silicone tube will be just inside the distal end of the airway tube. If necessary, an assistant can connect a bag-valve device to the silicone ET tube and ventilate the patient. Make sure that the longitudinal black line on the posterior surface of the silicone ET tube is facing upward.
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Slowly and gently advance the silicone ET tube 1.5 cm beyond the transverse black line. If no resistance is felt, the tip of the silicone tube is just past the vocal cords. Continue to advance the silicone ET tube an additional 4 cm (Figure 19-16E). The patient can be ventilated by an assistant during this procedure if necessary. Inflate the cuff of the silicone ET tube and ventilate the patient through the silicone ET tube (Figure 19-16F). Confirm proper tube placement by the auscultation of breath sounds, observation of chest rise, and end-tidal CO2 monitoring.
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The ILMA should now be withdrawn. Deflate the cuff of the ILMA. Have an assistant remove the bag-valve device and the 15 mm adapter on the proximal end of the silicone ET tube. Withdraw the ILMA by gently reversing the ILMA over the silicone ET tube (Figure 19-16G). Simultaneously apply slight pressure to the proximal end of the silicone ET tube so that it does not become dislodged (Figure 19-16G). When the mask begins to exit the patient's mouth, stop withdrawing the ILMA. Grasp the silicone ET tube firmly at the patient's mouth and hold it securely. Withdraw the ILMA in a smooth curved motion (Figure 19-16H). Reattach the standard respiratory connector, ventilate the patient, and reconfirm proper placement of the silicone ET tube.
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Some physicians prefer to use a “pusher” to prevent accidental extubation while the ILMA is being withdrawn. Cut a 25 cm length from a second silicone ET tube. Insert this into the ILMA as it is being removed. Apply slight pressure so it pushes against the first ET tube and prevents it from moving proximally. When the ILMA exits the patient's mouth, remove the ILMA and pusher as a unit. Secure and assess the proper positioning of the ET tube, as mentioned previously.
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The technique for inserting the LMA-CT is similar to that for the ILMA. The LMA-CT may be inserted from above the patient's head like the LMA-C or standing to the side of their head. Place the patient in the neutral position to avoid head extension. The manufacturer recommends only using the LMA-CT with straight, wire-reinforced cuffed silicone ET tubes with a 6.0 to 8.0 mm inner diameter. Standard curved plastic ET tubes may lead to an increased incidence of laryngeal trauma.
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Insert the LMA-CT using the technique described for the ILMA. Inflate the cuff with the recommended volume of air and confirm proper placement of the ILMA. Have an assistant attach a bag-valve device to the proximal end of the airway tube and ventilate the patient. Observe the upper chest rise, auscultate bilateral breath sounds, and observe end-tidal CO2 monitoring to confirm proper placement.
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Attach the Viewer by placing the Viewer's socket onto the magnetic latch connector on the LMA-CT. Turn on the Viewer to visualize the glottis. Lubricate the wire-reinforced silicone ET tube. Grasp the LMA-CT by its handle and pass the ET tube back-and-forth through the airway tube several times in order to lubricate the entire airway tube. Do not pass the lubricated silicone ET tube beyond the transverse black line on its posterior surface in order to avoid obscuring the fiberoptics with lubricant. Make sure that the longitudinal black line on the posterior surface of the silicone ET tube is facing upward.
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Slowly and gently advance the silicone ET tube 1.5 cm beyond the transverse black line. Gripping the handle and lifting a few millimeters optimize the alignment of the silicone ET tube and the trachea. As the silicone ET tube passes the mask aperture, the EEB will be seen to rise on the Viewer display. Continue to advance the silicone ET tube through the vocal cords. The patient can be ventilated by an assistant during this procedure if necessary. Detach the Viewer. Then, inflate the cuff of the silicone ET tube and ventilate the patient through the silicone ET tube. Confirm proper tube placement by the auscultation of breath sounds, observation of chest rise, and end-tidal CO2 monitoring. Withdraw the LMA-CT similar to the technique described for the ILMA.
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Other Laryngeal Mask Devices
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The Ambu Laryngeal Mask (Ambu LM), King Laryngeal Airway Device (King LAD), and the Air-Q Masked Laryngeal Airway (Air-Q) can be inserted and secured similar to the LMA. An ET tube can be inserted through all the Air-Q models similar to the ILMA.