- Email: [email protected]
Laryngeal mask airway longevity and pilot-balloon failure
Letters to the Editor
Laryngeal Mask Airway Longevity Pilot-Balloon Failure
and
Ms. Sharon Gee Product Manager Gensia, Inc. San Diego, CA
To the Editor: The life span of the laryngeal mask airway (LMA) in clinical practice is approximately 100 uses, and damage to the pilot balloon is a common cause of preuse test failures.’ Known causes of structural pilot-balloon failure include deterioration of the metallic valve (age related, accelerated by moisture and use of the wrong chemicals for cleaning/sterilization), loss of pilot-balloon integrity (direct trauma or cuff hyperinflation because of excessive air/moisture present during autoclaving),* and separation of the pilot tube from the LMA cuff (excessive traction on the pilot balloon tube).” We report two further causes of pilot balloon failure, awareness of which may increase the longevity of the LMA. The first was the discovery of a viscous black residue coating the pilot-balloon valve of several adult-sized LMAs that were inspected after they became difficult to inflate and deflate. We postulated that the residue was propofol, because it was not seen on the valves of the smaller LMAs that are used for pediatric patients, where inhalation inductions are the norm. This theory was subsequently confirmed by injecting a small volume of propofol into an LMA with a damaged tube and putting it through the autoclave cycle. Because propofol is the primary induction drug used for adults, there is always a large-volume “empty” syringe on the anesthesia cart following induction. Unfortunately, the temptation is to use the nearest, largest syringe to inflate the LMA. The second problem occurred during a difficult placement of a tonsillar gag for laser pharyngoplasty with a flexible LMA.4 Difficulty arose because the patient was edentulous and required several attempts at achieving gag stability. During one attempt, the pilot tube became trapped within the levering mechanism of the gag and was sheared in half during opening. The life span of the LMA is prolonged by careful use, strict adherence to cleaning and sterilization procedures, and by avoiding forceful removal of the device through partially clenched teeth. As with any reusable device, careful performance of the recommended preuse checks is the only reliable means of ensuring that it is safe to use, irrespective of the number of reuses. We would recommend that syringes used to inflate the LMA are labeled is focused on avoiding “air only”, and that attention accidental injection of propofol or other fluids. Surgeons must also be made aware of the potential damage their gags may cause to the device.
References Wat LI, Templin PA, Lynch ME, Hammamura RK, White PF: Use of the laryngeal mask airway for ambulatory anesthesia: utilization, longevity and cost [Abstract]. Anesthesiology 1996;85:A25. Brimacombe JR: Laryngeal mask residual volume and damage during sterilisation [Letter]. Anesth Analg 1994;79:391. Brimacombe JR, Brain AI, Berry A: The Laryngeal Mask Airway: Review and Practical Guide. London: W.B. Saunders Co., Ltd., 1997 (in press). Sher M, Brimacombe JR, Laing D: Anaesthesia for laser pharyngoplasty-a comparison of the tracheal tube with the reinforced laryngeal mask airway. Anaesth Intensive Care 1995;23:149-53. PI1 SO952-8180(97)0007&7
Longer Tube Length Eases Endotracheal Intubation via the Laryngeal Mask Airway iu Infants and Children To the Editor: Tracheal intubation using the laryngeal mask airway (LMA) is another way of securing the airway; however, a disadvantage of this method is that the conventional endotracheal tube is somewhat short for stable fixation.’ Longer tubes [e.g., the 33.3-cm, 5.0-mm internal diameter (ID) Mallinckrodt Microlaryngeal Tube (Mallinckrodt, Inc., St. Louis, MO),’ or the nasal RAE tubes] have been used for endotracheal intubation through the LMA in adult practice. Intubation through the LMA has been reported in infants and children, using conventional tubes.4,5 I would like to remind my pediatric anesthesia colleagues of the fact that longer pediatric tubes are available. The Portex Blueline Croup endotracheal tube (#lOO/ 112, Portex, Kent, UK) is available in the following lengths and IDS: 220 mm (2.5-mm ID), 250 mm (3.0-mm ID), 280 mm (3.5-mm ID), 310 mm (4.0-mm ID), 330 mm (4.5-mm ID), and 330 mm (5.0-mm ID) lengths. Masao Yamashita, MD Anesthetist-in-Chief Department of Anesthesiology Ibaraki Children’s Hospital Mito, Ibaraki, Japan
Linda I. Wat, MD Attending Anesthesiologist Loma Linda University Loma Linda, CA
References Joseph R. Brimacombe, MB ChB, FRCA, MD Clinical Associate Professor University of Queensland Cairns Base Hospital, Cairns, Australia
432
J. Clin. Anesth., vol. 9, August 1997
1. Asai T, Patto IP, Vaughan Rs: The distance between the grille of the laryngeal mask airway and the vocal cords. Is conventional intubation through the laryngeal mask safe? Anaesthesia 1993;48: 667-Q.
Laryngeal Mask Airway Longevity Pilot-Balloon Failure
and
Ms. Sharon Gee Product Manager Gensia, Inc. San Diego, CA
To the Editor: The life span of the laryngeal mask airway (LMA) in clinical practice is approximately 100 uses, and damage to the pilot balloon is a common cause of preuse test failures.’ Known causes of structural pilot-balloon failure include deterioration of the metallic valve (age related, accelerated by moisture and use of the wrong chemicals for cleaning/sterilization), loss of pilot-balloon integrity (direct trauma or cuff hyperinflation because of excessive air/moisture present during autoclaving),* and separation of the pilot tube from the LMA cuff (excessive traction on the pilot balloon tube).” We report two further causes of pilot balloon failure, awareness of which may increase the longevity of the LMA. The first was the discovery of a viscous black residue coating the pilot-balloon valve of several adult-sized LMAs that were inspected after they became difficult to inflate and deflate. We postulated that the residue was propofol, because it was not seen on the valves of the smaller LMAs that are used for pediatric patients, where inhalation inductions are the norm. This theory was subsequently confirmed by injecting a small volume of propofol into an LMA with a damaged tube and putting it through the autoclave cycle. Because propofol is the primary induction drug used for adults, there is always a large-volume “empty” syringe on the anesthesia cart following induction. Unfortunately, the temptation is to use the nearest, largest syringe to inflate the LMA. The second problem occurred during a difficult placement of a tonsillar gag for laser pharyngoplasty with a flexible LMA.4 Difficulty arose because the patient was edentulous and required several attempts at achieving gag stability. During one attempt, the pilot tube became trapped within the levering mechanism of the gag and was sheared in half during opening. The life span of the LMA is prolonged by careful use, strict adherence to cleaning and sterilization procedures, and by avoiding forceful removal of the device through partially clenched teeth. As with any reusable device, careful performance of the recommended preuse checks is the only reliable means of ensuring that it is safe to use, irrespective of the number of reuses. We would recommend that syringes used to inflate the LMA are labeled is focused on avoiding “air only”, and that attention accidental injection of propofol or other fluids. Surgeons must also be made aware of the potential damage their gags may cause to the device.
References Wat LI, Templin PA, Lynch ME, Hammamura RK, White PF: Use of the laryngeal mask airway for ambulatory anesthesia: utilization, longevity and cost [Abstract]. Anesthesiology 1996;85:A25. Brimacombe JR: Laryngeal mask residual volume and damage during sterilisation [Letter]. Anesth Analg 1994;79:391. Brimacombe JR, Brain AI, Berry A: The Laryngeal Mask Airway: Review and Practical Guide. London: W.B. Saunders Co., Ltd., 1997 (in press). Sher M, Brimacombe JR, Laing D: Anaesthesia for laser pharyngoplasty-a comparison of the tracheal tube with the reinforced laryngeal mask airway. Anaesth Intensive Care 1995;23:149-53. PI1 SO952-8180(97)0007&7
Longer Tube Length Eases Endotracheal Intubation via the Laryngeal Mask Airway iu Infants and Children To the Editor: Tracheal intubation using the laryngeal mask airway (LMA) is another way of securing the airway; however, a disadvantage of this method is that the conventional endotracheal tube is somewhat short for stable fixation.’ Longer tubes [e.g., the 33.3-cm, 5.0-mm internal diameter (ID) Mallinckrodt Microlaryngeal Tube (Mallinckrodt, Inc., St. Louis, MO),’ or the nasal RAE tubes] have been used for endotracheal intubation through the LMA in adult practice. Intubation through the LMA has been reported in infants and children, using conventional tubes.4,5 I would like to remind my pediatric anesthesia colleagues of the fact that longer pediatric tubes are available. The Portex Blueline Croup endotracheal tube (#lOO/ 112, Portex, Kent, UK) is available in the following lengths and IDS: 220 mm (2.5-mm ID), 250 mm (3.0-mm ID), 280 mm (3.5-mm ID), 310 mm (4.0-mm ID), 330 mm (4.5-mm ID), and 330 mm (5.0-mm ID) lengths. Masao Yamashita, MD Anesthetist-in-Chief Department of Anesthesiology Ibaraki Children’s Hospital Mito, Ibaraki, Japan
Linda I. Wat, MD Attending Anesthesiologist Loma Linda University Loma Linda, CA
References Joseph R. Brimacombe, MB ChB, FRCA, MD Clinical Associate Professor University of Queensland Cairns Base Hospital, Cairns, Australia
432
J. Clin. Anesth., vol. 9, August 1997
1. Asai T, Patto IP, Vaughan Rs: The distance between the grille of the laryngeal mask airway and the vocal cords. Is conventional intubation through the laryngeal mask safe? Anaesthesia 1993;48: 667-Q.