Laryngeal Mask Airway (Excerpt)
The laryngeal mask airway (LMA) is a device used to secure the airway in an unconscious patient. The LMA consists of a tube with a cuffed mask-like projection at the distal end. The LMA is introduced into the pharynx and advanced until resistance is felt as the tube locates in the hypopharynx. The balloon cuff is then inflated, which seals the hypopharynx, leaving the distal opening of the tube just above the glottic opening and providing a clear, secure airway.
LMAs are widely used in the operating room and provide an effective means of ventilation and oxygenation, but LMAs are contraindicated in an infant or child with an intact gag reflex. They may be useful in patients with difficult airways, and have been used successfully in emergency airway control of adults in hospital and out-of-hospital settings.1,2 They can be placed safely and reliably in infants and children,3 although data suggest that proper training and supervision are needed to master the technique.4,5
Data also suggest that mastering LMA insertion may be easier than mastering endotracheal intubation.6 Indeed, nurses have been successfully trained to perform LMA insertion in adults in cardiac arrest,7 and paramedics have been trained to insert an LMA with a higher success rate than endotracheal intubation.8
Although LMAs do not protect the airway from aspiration of refluxed gastric contents, a meta-analysis shows that aspiration is uncommon with LMA use in the operating room9 and was less common than with bag-mask ventilation in adults undergoing in-hospital CPR.10 Therefore, in the setting of cardiac or respiratory arrest, LMAs may be an effective alternative for establishing the airway when inserted by properly trained health care providers, but limited data comparing LMAs to bag-mask ventilation or endotracheal intubation in emergency pediatric resuscitation preclude a confident recommendation. Training for health care providers in the use of the LMA should not replace training to use bag-mask ventilation effectively.
An LMA may be more difficult to maintain during patient movement than a tracheal tube, making it problematic to use during transport. Careful attention is needed to ensure that the LMA position is maintained if the LMA is used in the out-of-hospital setting. Furthermore, the LMA is relatively expensive, and a number of sizes are needed to provide airway support to any child at risk. The cost of equipping out-of-hospital providers with LMA devices must be considered.
References
1. Rumball CJ, MacDonald D. The PTL, Combitube, laryngeal mask, and oral airway: A randomized prehospital comparative study of ventilatory device effectiveness and cost-effectiveness in 470 cases of cardiorespiratory arrest. Prehosp Emerg Care 1997; 1:1-10.
2. Martin SE, Ochsner MG, Jarman RH, et al. Use of the laryngeal mask airway in air transport when intubation fails. J Trauma 1999; 47:352-357.
3. Berry AM, Brimacombe JR, Verghese C. The laryngeal mask airway in emergency medicine, neonatal resuscitation, and intensive care medicine. Int Anesthesiol Clin 1998; 36:91-109.
4. Lopez-Gil M, Brimacombe J, Cebrian J, et al. Laryngeal mask airway in pediatric practice: A prospective study of skill acquisition by anesthesia residents. Anesthesiology 1996; 84:807-811.
5. Lopez-Gil M, Brimacombe J, Alvarez M. Safety and efficacy of the laryngeal mask airway: A prospective survey of 1,400 children. Anaesthesia 1996; 51:969-972.
6. Brimacombe J. The advantages of the LMA over the tracheal tube or facemask: A meta-analysis. Can J Anaesth 1995; 42:1,017-1,023.
7. Baskett PJF. The use of the laryngeal mask airway by nurses during cardiopulmonary resuscitation: Results of a multicentre trial. Anaesthesia 1994; 49:3-7.
8. Pennant JH, Walker MB. Comparison of the endotracheal tube and laryngeal mask in airway management by paramedical personnel. Anesth Analg 1992; 74:531-534.
9. Brimacombe JR, Berry A. The incidence of aspiration associated with the laryngeal mask airway: A meta-analysis of published literature. J Clin Anesth 1995; 7:297-305.
10. Stone BJ, Chantler PJ, Baskett PJ. The incidence of regurgitation during cardiopulmonary resuscitation: A comparison between the bag valve mask and laryngeal mask airway. Resuscitation 1998; 38:3-6.
Source: Reproduced with permission. American Heart Association in collaboration with the International Liaison Committee on Resuscitation. Guidelines 2000 for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care: International Consensus on Science, Part 10: Pediatric Advanced Life Support. Circulation 2000; (suppl I):I-291-I-342. ©American Heart Association.
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