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Good Intubators Do It More Often
Prehospital endotracheal intubation (ETI) is a form of advanced life support that is both potentially lifesaving and technically difficult. The purpose of ETI is to provide oxygen to a patient, improve ventilation and prevent aspiration of stomach contents. The procedure, and specifically who should be considered qualified to attempt it, has been a topic of controversy, fueled in part by conflicting research.
One can find greater consensus, however, regarding the relationship between adequate training and higher success rates for ETI. It is a skill that depends upon practice to maintain proficiency and produce favorable outcomes.1 This article seeks to assess current ETI procedures and training in South Carolina, and to provide insight on how the relationship affects clinical outcomes across the state. Specifically, does the ability to perform a higher quantity or frequency of the procedure lead to improved ETI outcomes?
When investing resources for EMS training, one must balance the utility of teaching a skill that may rarely be used with the importance of mastering a procedure that could potentially save lives. Low-volume services, such as those in some rural parts of South Carolina, may not see a return on investment when directing training resources toward ETI when there are so few opportunities to attempt it in the field.2 For first responders who implement the procedure, training should be provided in a manner that offers maximum benefit.
According to the South Carolina Department of Health and Environmental Control (DHEC), EMTs with a Basic designation are eligible to perform intubations, provided they are affiliated with a state-licensed ambulance provider and obtain authority from the provider's medical control physician.3 On a national level, the published range of prehospital ETI success ranges from 49%-99%.4 The broad variance promotes disagreement over the effectiveness of prehospital ETI, and the range of success rates seen nationally is mirrored in South Carolina data.
METHODOLOGY
To assess the current procedures and intubation outcomes in the state, the University of South Carolina's Institute for Public Service and Policy Research (IPSPR) conducted a survey. The survey was initially piloted among a small group of county EMS departments that participate in an IPSPR county EMS benchmarking project. Participants were asked about their departments' ETI success rates, training procedures, alternative airway policies, and which staff members were considered qualified to perform intubations. Seven county EMS departments provided data.
The results indicated that a relationship may exist between the amount of time devoted to training staff on intubation procedures and higher intubation success rates. Although a positive correlation was demonstrated, the small sample size made it difficult to draw reliable conclusions. For this reason, investigators broadened the sample to include a large group of relevant agencies across the state. Prior to the release of the statewide survey, they incorporated feedback from the original sample into the survey instrument. The survey training hours content was broken into two questions to assess total hours of intubation training each employee received per year, plus frequency of intubation training per year. This would allow analysis of whether total training hours or frequency of training was more strongly related to higher ETI success rates.
The revised survey was mailed in September 2007 to 177 agencies. These included any entity that might be responsible for providing prehospital endotracheal intubations, such as county EMS departments, transport agencies, fire departments with first responders, and volunteer rescue squads. Thirty-seven agencies provided data in response. To further increase the sample, the DHEC assisted IPSPR by sending a follow-up e-mail to the agencies in November 2007 with an electronic version of the survey attached.
Any agency that indicated fewer than four intubations per year was excluded from analysis, as this frequency was determined insufficient to calculate a reliable rate. National EMS Information System definitions were used to define endotracheal intubation attempts and success. Overall ETI success rates were calculated as the total number of successful intubations divided by the total number of attempts.
RESULTS
Of agencies receiving one of the 177 surveys, 48 (27%) responded. Of these, overall ETI success rates were calculated and correlated with total annual training hours and annual training frequency for 26 and 28 services, respectively. An overall success rate of 81.1% was calculated as the average for all services combined.
When ETI success rates were compared to total annual training hours, no correlation was demonstrated in the data. However, a relationship was found to exist between ETI success rates and ETI training frequency, indicating that it may be more important to be exposed to ETI training throughout the year than to receive a number of training hours all at once.
Reported total training ranged from 0-16 annual hours, with a frequency of training sessions range of zero to monthly. Median training hours were six, and median frequency was twice annually. Respondents also reported a wide variety of agency training procedures. The most frequently cited expectation was five intubations on adult and child manikins. A number had lesser requirements to demonstrate skill (for example, three successful intubations or one successful intubation each via ETI and an alternative airway device), while other services indicated that all training was didactic and no specific measures of competency were implemented. The American Heart Association recommends frequent intubations or frequent retraining to maintain the ETI skill. It notes that the incidence of complications (such as tube misplacement) is unacceptably high when ETI is performed by inexperienced providers.5 Some of the barriers local EMS providers face in obtaining ETI training include small service areas or numerous staff members qualified to intubate (which decreases each individual's opportunity for on-the-job practice), as well as the difficulty in gaining access to operating rooms to get experience. Of the services that indicated specific intubation requirements during training, only manikins were cited as a method for skill maintenance.
ALTERNATIVE AIRWAYS
An important variable to consider when assessing the number of ETIs performed is the clinical condition of the patients receiving the procedure. Changing technology and practice in airway devices may influence the number and types of patients requiring ETI. For example, CPAP devices have been demonstrated to reduce the need for ETI in some patients with acute respiratory failure.6 According to the IPSPR survey, 67% of responding South Carolina services had access to CPAP. Anecdotally, some services indicated that CPAP had recently been implemented or would be in the near future. This may indicate that the proportion of services with access to CPAP is likely to grow. Use of CPAP may lead to a reduced number of patients requiring ETI, and also alter the profile of those needing ETI to include a higher proportion of patients with difficult airways, such as those who have experienced severe trauma. Another factor to consider, however, is that for those patients for whom CPAP is an appropriate airway management technique, all responding services indicated that CPAP either never or rarely fails, requiring subsequent ETI. Increasing use of CPAP and its effects on conscious intubation is a national trend and will likely continue to influence prehospital practice.7
Across South Carolina, services that perform ETI reported a range of policies regarding intubation attempts. Thirty percent reported no formal policy, while some indicated the number of attempts was left to the crew chief's discretion. Those who had developed specific ETI policies indicated a range of 1-3 ETI attempts as permissible before switching to alternative airways. Due to the chaotic nature of prehospital ETI, rescuers often attempt to intubate several times before securing an airway. It is important to note that research has demonstrated that the probability of successful intubation decreases after three attempts, and multiple ETI attempts can produce negative clinical ramifications, such as injury to the trachea.8 Alternate airway devices commonly used in South Carolina are listed in Table 1.
POLICY OPTIONS
Decisions regarding statewide policy changes demand careful consideration of prehospital ETI procedures and the complex interaction between training opportunities, staffing and alternative methods of providing ventilation. During cardiac arrest, patients have demonstrated improved survival rates when ETI is provided more quickly, which emphasizes the key role first responders play.13 However, the procedure is associated with a number of serious complications, including dental and oral soft tissue trauma, hypertension and tachycardia, cardiac dysrhythmias, myocardial ischemia and aspiration of gastric contents, as well as a number of complications that can occur while the tube is in place and during removal.14
Although conclusive evidence is limited by the small sample, data from the South Carolina IPSPR survey demonstrates that increased exposure to ETI training throughout the year is associated with better patient outcomes. There are two primary methods for incorporating this information into practice. One is to increase training, and the other is to decrease the number of responders qualified to perform the procedure, thereby allowing a smaller number of professionals more practice in the field. Potential benefits of the latter method will likely vary depending on the agency and population served. A report by the International City/County Management Association emphasized that meeting the American Heart Association minimum of 6-12 annual intubations per provider to maintain proficiency is not possible in many communities.15
While changing responder qualifications for the ETI procedure is a policy worth considering, an effective method of maintaining proficiency is to ensure adequate training. CPAP is just one example of how changing technology will influence prehospital emergency care. As new devices are developed and improved, EMS agencies must determine how best to implement available resources.
Table I: Alternative Airway Devices
Laryngeal mask airway (LMA): Forms a low-pressure seal around the laryngeal inlet when blindly inserted.9
Combitube: A double-lumen tube with distal and proximal cuffs, associated with very few problems in achieving ventilation.10
King Airway: A curved tube with two inflatable cuffs, designed to seal the esophagus.11
Airtraq: A single-use laryngoscope that allows full visualization of the airway during intubation.12
Continuous positive airway pressure (CPAP): A constant pressure is set during inspiration and expiration using a noninvasive mask.
References
1. Russi CS, Wilcox CL, House HR. The laryngeal tube device: A simple and timely adjunct to airway management. Am J Emerg Med 25(3): 263-67, 2006.
2. Burton J. Out-of-hospital intubation: Half empty or half full? Ann Emerg Med 76(6): 542-43, 2006.
3. Department of Health and Environmental Control, Division of Emergency Medical Services. Guidelines for Approved In-Service Training Program, www.dhec.sc.gov/health/ems/cskills.pdf.
4. Albrecht E, Yersin B, Spahn DR, Fishman D, Hugli O. Success rate of airway management by residents in a pre-hospital emergency setting: A retrospective study. Eur J Trauma 6: 516-22, 2006.
5. American Heart Association. Part 7.1: Adjuncts for Airway Control and Ventilation. Circ 112: IV-51-IV-57, 2005.
6. Kramer N, Meyer TJ, Meharg J, Cece RD, Hill NS. Randomized, prospective trial of noninvasive positive pressure ventilation in acute respiratory failure. Am J Resp Crit Care Med 151(6): 1,799, 1995.
7. Williams DM. 2006 JEMS 200-city survey. J Emerg Med Serv 32(2): 38-42, 44, 46, Feb 2007.
8. Wang HE, Yealy DM. How many attempts are required to accomplish out-of-hospital intubations? Acad Emerg Med 13: 372-77, 2006.
9. Crosby et al. The unanticipated difficult airway with recommendations for management. Can J Anesth 45(7): 757-76, Feb 1998.
10. Ibid.
11. King Airway. Instructions for Use: King LT Oropharyngeal Airway, https://kingsystems.com.
12. King Airway. Airtraq Optical Laryngoscope: Instructions for Use, https://kingsystems.com.
13. Shy BD, Rea TD, Becker LJ, Eisenberg MS. Time to intubation and survival in prehospital cardiac arrest. Preh Emerg Care 8: 394, 2004.
14. Stoelting RK, Miller RD. Basics of Anesthesia. New York: Churchill Livingstone, 2000.
15. Fitch J, Griffiths K. EMS in Critical Condition: Meeting the Challenge. ICMA IQ Report 37(5), 2005.
At the completion of this project, Amanda Jane Reich, MPH, was a research associate at the Institute for Public Service and Policy Research. She is currently studying in Boston, MA. This article was written with assistance from senior research associates Anna Berger, MPA, and William Tomes, MHR.
