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August 1, 2013

Breathe easier: Devices that improve ventilation

During the early days of EMS development, three airway control and ventilation methods existed in the prehospital arena; head positioning with bag-valve-mask (BVM) ventilation, esophageal obturator airways (EOA), and endotracheal intubation.  Early researchers demonstrated that even experienced EMTs and paramedics had difficulty providing effective ventilation when using head-positioning and the BVM (Elling & Politis, 1983). 

Researchers in South Carolina found the failure rate of the esophageal cuffs in EOAs to be unacceptably high (Bass, Allison, & Hunt, 1982) while researchers in Iowa reported significant displacement of the larynx and trachea following EOA insertion (Low, Jensen, & Cavanaugh, 1982).  Multiple case reports from that time reported both esophageal and gastric rupture following EOA insertion by trained prehospital crewmembers (Adler & Dykan, 1983; Crippen, Olvey, & Graffis, 1981; Harrison, Nord, & Beeman, 1980). 

Experts considered the endotracheal tube as the most the most efficacious airway control device and encouraged EMS to adopt endotracheal intubation as the airway of choice for many critically ill or injured patients (Pepe, Copass, & Joyce, 1985).  Moreover, early American Heart Association guidelines classified endotracheal intubation as a “definitely helpful” intervention for cardiac arrest resuscitation (American Heart Association, 1992).

Endotracheal intubation as gold standard?

Subsequently, paramedics and prehospital medical directors began accepting endotracheal intubation as the “gold standard” of airway control (Dickinson, Cohen, & Mechem, 1999) as the procedure allowed advanced providers to establish, maintain, and protect the airway from aspiration. 

Endotracheal intubation also facilitates oxygenation and ventilation, prevents airflow into the stomach during BVM ventilation, provides a route for some medications when IV access is not available, and permits suctioning of the trachea and bronchi (Saunders, 2012).

A direct relationship exists between skill proficiency and skill performance (Latman & Wooley, 1980).  EMS personnel are more successful with skills they perform on a regular basis.  In order to remain proficient at tracheal intubation, an expert panel on airway management at the Proceedings of the Guidelines 2000 Conference for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care recommended that every paramedic within an EMS system perform at least 10 out-of-hospital intubations each year (Barnes et al., 2001).  The panel further recommended that the agency delivering EMS should provide considerable retraining for any paramedic who could not meet that minimum standard. 

Evidence suggests that the yearly mean average for paramedics may be half that amount and that 40% of medics may not have an opportunity for endotracheal intubation in any given year (Wang et al., 2005).

A variety of airway devices

Given that the efficacy of tracheal intubation is questionable, the high incidence of misplaced tracheal tubes, and the low frequency of intubation per individual medic, many EMS systems are searching for alternative airway control devices.  The ideal device would be easy to place by every medic in the system, even those that may not often treat many critical patients.  The device would also have to be safe for patients and must provide ventilation that is at least equal to the tracheal tube.

Supraglottic airway devices

The most common advanced airway used alternatively to endotracheal intubation belongs to a group called supraglottic airways.  There are many varieties of supraglottic airway devices (SAD) however, there are only four basic categories; laryngeal masks, laryngeal tubes, double-lumen tubes, or the miscellaneous or other SAD.  One feature common to the four categories is that rescuers can insert the devices without direct laryngoscopy.  This makes the devices attractive because EMS personnel find both the initial training and skill maintenance easier when compared to endotracheal intubation (Russi, & Miller, & Hartley, 2008; Russi, Wilcox, & House, 2007). 

Also, since the devices do not require direct laryngoscopy, EMS personnel can insert them without having to interrupt chest compressions in patients suffering from cardiac arrest.  This will increase the total amount of time that rescuers are pushing on the chest.

When properly trained, EMS personnel can safely provide ventilation that is at least as effective as ventilation provided with a bag-valve mask or an endotracheal tube (Cady, Weaver, Pirrallo, & Wang, 2009; Dörges, Wenzel, Knacke, & Gerlach, 2003; SOS-Kantos Study Group, 2009).

Recently, researchers with the Resuscitation Outcomes Consortium (Wang et al., 2012) retrospectively examined airway data from two previously published cardiac arrest outcome studies (Aufderheide et al., 2011; Stiell et al., 2011).  The researchers found that adult patients who suffered an out-of-hospital cardiac arrest were about one and one-half times more likely to survive to hospital discharge with satisfactory functional status if EMS personnel inserted an endotracheal tube compared to SGA insertion.  Secondary data analysis found the odds of survival were almost two times greater if EMS used a bag-valve mask (BVM) than if they used any of the advanced airways.  An animal study suggests that SGA cuff inflation (even to the manufacturer’s recommendation) may cause carotid artery compression with a concomitant 15-50% reduction in blood flow to the brain when compared to ETI or no advanced airway (Segal et al., 2012).

Video assisted laryngoscopy

One important newcomer to the field of prehospital airway management is indirect fiberoptic or video-laryngoscopy.  These devices permit visualization of the laryngeal structure through a view tube with a lens system or through a digital camera lens embedded in the laryngoscope blade. 

Video-laryngoscopy improves glottis visualization in a manikin with the greatest improvements seen in simulated difficult airway scenarios (Aziz, Dillman, Kirsch, & Brambrink, 2009).  Compared with direct laryngoscopy, video laryngoscopy improved visualization of the airway structures in patients requiring emergency airway maneuvers outside of an operation room. (Jones, Agrawal, & Schulte, 2013). 

No perfect airway device

EMS personnel must be aware that no perfect airway control device exists.  Each presents with its own benefits and risks.  Endotracheal intubation may provide many advantages; however, the literature highlights numerous complications associated with this procedure in the prehospital environment. 

Supraglottic airways are a reasonable alternative to endotracheal intubation and may reduce some of the risks of advanced airway placement seen with endotracheal tubes.  Likewise, video-laryngoscopy appears to improve glottic visualization; however, there utility of that technology in the out-of-hospital environment remains unknown.

It is worth noting that no definitive evidence exists that demonstrates improved survival rates offered by insertion of an advanced airway for patients who suffered cardiac arrest (Neumar et al., 2010).  When compared to bag-valve-mask ventilation, the use of any advanced airway during the resuscitation attempt from out-of-hospital cardiac arrest decreases neurologically favorable survival (Hasegawa, Hiraide, Chang, & Brown, 2013).

 

References

  1. Adler, J., & Dykan, M.  (1983). Gastric rupture: an unusual complication of the esophageal obturator airway. Annals of Emergency Medicine, 12(4), 224-225.
  2. American Heart Association.  (1992).  Guidelines for cardiopulmonary resuscitation and emergency cardiac care: Emergency Cardiac Care Committee and subcommittees, American Heart Association, part III: adult advanced cardiac life support. Journal of the American Medical Association, 268, 2199-2241.
  3. Aufderheide, T. P., Nichol, G., Rea, T. D., Brown, S. P., Leroux, B. G., Pepe, P. E., Kudenchuk, P. J., Christenson, J., Daya, M. R., Dorian, P., Callaway, C. W., Idris, A. H., Andrusiek, D., Stephens, S. W., Hostler, D., Davis, D. P., Dunford, J. V., Pirrallo, R. G., Stiell, I. G., Clement, C. M., Craig, A., Van Ottingham, L., Schmidt, T. A., Wang, H. E., Weisfeldt, M. L., Ornato, J. P., Sopko, G. & the Resuscitation Outcomes Consortium (ROC) Investigators. (2011). A trial of an impedance threshold device in out-of-hospital cardiac arrest. New England Journal of Medicine, 365(9), 798-806. doi:10.1056/NEJMoa1010821
  4. Aziz, M., Dillman, D., Kirsch, J. R., & Brambrink, A. (2009). Video laryngoscopy with the macintosh video laryngoscope in simulated prehospital scenarios by paramedic students.  Prehospital Emergency Care, 13(2), 251-255. doi:10.1080/10903120802706070.
  5. Barnes, T. A., MacDonald, D., Nolan, J., Otto, C., Pepe, P., Sayre, M. R., Shuster, M., & Zaritsky, A.  (2001). Airway Devices.  Annals of Emergency Medicine, 37(4), S145-S151
  6. Bass, R. R., Allison, E. J., Jr., & Hunt, R. C.  (1982).  The esophageal obturator airway: A reassessment of use by paramedics. Annals of Emergency Medicine, 11(7), 358-360.
  7. Cady, C. E., Weaver, M. D., Pirrallo, R. G., & Wang, H. E. (2009). Effect of emergency medical technician-placed Combitubes on outcomes after out-of-hospital cardiopulmonary arrest. Prehospital Emergency Care, 13(4), 495–499. doi:10.1080/10903120903144874
  8. Crippen, D., Olvey, S., & Graffis, R. (1981). Gastric rupture: An esophageal obturator airway complication. Annals of Emergency Medicine, 10(7), 370-373.
  9. Dickinson, E. T., Cohen, J. E., & Mechem, C. C. (1999). The effectiveness of midazolam as a single pharmacologic agent to facilitate endotracheal intubation by paramedics. Prehospital Emergency Care, 3(3), 191-193.
  10. Dörges, V., Wenzel, V., Knacke, P., & Gerlach, K. (2003). Comparison of different airway management strategies to ventilate apneic, nonpreoxygenated patients. Critical Care Medicine, 31(3), 800–804. doi:10.1097/01.CCM.0000054869.21603.9A
  11. Elling, R., & Politis, J. (1983).  An evaluation of emergency medical technicians' ability to use manual ventilation devices.  Annals of Emergency Medicine, 12(12), 765-768.
  12. Harrison, E. E., Nord, H. J., & Beeman, R. W. (1980). Esophageal perforation following use of the esophageal obturator airway. Annals of Emergency Medicine, 9(1), 21-25.
  13. Hasegawa, K., Hiraide, A., Chang, Y., & Brown, D. F. (2013). Association of prehospital advanced airway management with neurologic outcome and survival in patients with out-of-hospital cardiac arrest.  Journal of the American Medical Association, 309(3), 257-266. doi:10.1001/jama.2012.187612
  14. Jones, B. M., Agrawal, A., & Schulte, T. E. (2013). Assessing the efficacy of video versus direct laryngoscopy through retrospective comparison of 436 emergency intubation cases. Journal of Anesthesia, 13 Jun 13. [Epub ahead of print] doi:10.1007/s00540-013-1651-3
  15. Latman, N. S., & Wooley, K.  (1980). Knowledge and skill retention of emergency care attendants, EMT-As and EMT-Ps. Annals of Emergency Medicine, 9(4), 183-189.
  16. Low, R. B., Jensen, R. D., & Cavanaugh, K. J.  (1982).  Marked anterior displacement of the trachea and larynx from an esophageal obturator airway (EOA). Annals of Emergency Medicine, 11(12), 670-672.
  17. Neumar, R. W., Otto, C. W., Link, M. S., Kronick, S. L., Shuster, M., Callaway, C. W., Kudenchuk, P. J., Ornato, J. P., McNally, B., Silvers, S. M., Passman, R. S., White, R. D., Hess, E. P., Tang, W., Davis, D., Sinz, E., & Morrison, L. J. (2010). Part 8: Adult advanced cardiovascular life support: 2010 American Heart Association guidelines for cardiopulmonary resuscitation and emergency cardiovascular care. Circulation, 122[suppl 3], S729–S767. doi:10.1161/CIRCULATIONAHA.110.970988
  18. Pepe, P. E., Copass, M. K., & Joyce, T. H. (1985). Prehospital endotracheal intubation: rationale for training emergency medical personnel. Annals of Emergency Medicine, 14(11), 1085-1092.
  19. Russi, C. S., & Miller, L., & Hartley, M. J.  (2008).  A comparison of the King-LT to endotracheal intubation and Combitube in a simulated difficult airway. Prehospital Emergency Care, 12(1), 35-41. doi:10.1080/10903120701710488
  20. Russi, C. S., Wilcox, C. L., & House, H. R.  (2007).  The laryngeal tube device: a simple and timely adjunct to airway management. American Journal of Emergency Medicine, 25(3), 263–267. doi:10.1016/j.ajem.2006.03.018
  21. Saunders, M. (2012).  Mosby’s Paramedic Textbook (4th ed).  St Louis: Mosby.
  22. Segal, N., Yannopoulos, D., Mahoney, B. D., Frascone, R. J., Matsuura, T., Cowles, C. G., McKnite, S. H., & Chase, D. G. (2012). Impairment of carotid artery blood flow by supraglottic airway use in a swine model of cardiac arrest. Resuscitation, 83(8), 1025-1030. doi:10.1016/j.resuscitation.2012.03.025
  23. Serocki, G., Neumann, T., Scharf, E., Dörges, V., & Cavus, E. (2013). Indirect videolaryngoscopy with C-MAC D-Blade and GlideScope: A randomized, controlled comparison in patients with suspected difficult airways. Minerva Anestesiologica, 79(2), 121-129.
  24. SOS-Kantos Study Group. (2009). Comparison of arterial blood gases of laryngeal mask airway and bag-valve- mask ventilation in out-of-hospital cardiac arrests. Circulation Journal, 73(3), 490–496.
  25. Stiell, I. G., Nichol, G., Leroux, B. G., Rea, T. D., Ornato, J. P., Powell, J., Christenson, J., Callaway, C. W., Kudenchuk, P. J., Aufderheide, T. P., Idris, A. H., Daya, M. R., Wang, H. E., Morrison, L. J., Davis, D., Andrusiek, D., Stephens, S., Cheskes, S., Schmicker, R. H., Fowler, R., Vaillancourt, C., Hostler, D., Zive, D., Pirrallo, R. G., Vilke, G. M., Sopko, G., Weisfeldt, M. & the Resuscitation Outcomes Consortium Investigators. (2011). Early versus later rhythm analysis in patients with out-of-hospital cardiac arrest. New England Journal of Medicine, 365(9), 787-797. doi:10.1056/NEJMoa1010076
  26. Wang, H. E., Kupas, D. F., Hostler, D., Cooney, R., Yealy, D. M., & Lave, J. R. (2005).  Procedural experience with out-of-hospital endotracheal intubation. Critical Care Medicine, 33(8), 1718 –1721. doi:10.1097/01.CCM.0000171208.07895.2A
  27. Wang, H. E., Szydlo, D., Stouffer, J. A., Lin, S., Carlson, J. N., Vaillancourt, C., Sears, G., Verbeek, R. P., Fowler, R., Idris, A. H., Koenig, K., Christenson, J., Minokadeh, A., Brandt, J., Rea, T.,  & the ROC Investigators. (2012). Endotracheal intubation versus supraglottic airway insertion in out-of-hospital cardiac arrest, Resuscitation, 83(9), 1061-1066. doi:10.1016/j.resuscitation.2012.05.018

About the Author

Kenny Navarro is an Assistant Professor in the Department of Emergency Medicine at the University of Texas Southwestern Medical School at Dallas. He also serves as the AHA Training Center Coordinator for Tarrant County College. Mr. Navarro serves as an Emergency Cardiovascular Care Content Consultant for the American Heart Association, served on two education subcommittees for NIH-funded research projects, as the Coordinator for the National EMS Education Standards Project, and as an expert writer for the National EMS Education Standards Implementation Team. Send correspondence concerning any articles in this section to Kenneth W. Navarro, The University of Texas Southwestern Medical School at Dallas, 5323 Harry Hines Blvd MC 8890, Dallas, Texas 75390-8890, or e-mail kenny.navarro@ems1.com.
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