EMS World

JAN 2018

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EMSWORLD.com | JANUARY 2018 25 W ith more than 300 bases in 48 states and around 4,500 team members, Air Meth- ods is the country's largest air-medical provider. It carries around 100,000 seriously ill and injured patients per year, many of whom require airway management. But across the company a few years back, intubation was proving a problem. It just wasn't happening as quickly and trou- ble-free as anyone wanted. First-attempt success rates needed improvement, and adverse events needed to be minimized. There was plenty of data to scrutinize, and top company leaders burrowed into it. What they discovered ultimately led to the development of a new tool that's showing promise in streamlining airway care in the flight and other difficult environments. "We saw it wasn't just one area or one region having problems—it was across the country," says Dave Olvera, NRP, FP-C, CMTE, the company's clinical education manager. "And when we really looked at it, we realized the LEMON criteria is phe- nomenal—it really works well—but there's little to no research that shows it's success- ful in the prehospital or emergent setting. We wanted to find something that could accommodate all of the flight setting, the ground setting, and what I call the 'out of the operating room experience,' where you have that crash airway in the NICU, in the emergency department, in the air—any of those situations—and address them all together." The result was HEAVEN, an acronym for six key attributes that can help crews deter- mine the likelihood an emergency-intuba- tion patient will pose a difficult airway. HEAVEN stands for: Hypoxemia Extremes of size Anatomic challenges Vomit/blood/fluid Exsanguination/anemia Neck mobility issues. The criteria were derived through a ret- rospective review of records for more than 500 patients who'd needed rapid sequence intubation in an air-med setting. 1 Sixty-three of those required more than one intubation attempt; the reasons for that were grouped to discern the main categories. The resulting criteria "represent a set of difficult airway predictors that may be applied prospectively by emergency airway personnel, facilitating airway decision mak- ing," Olvera and coauthor Daniel Davis, MD, wrote, but should also be validated pro- spectively. 1 Built to Evolve HEAVEN rolled out in 2015, and it's now used companywide by Air Methods and has been adopted by several other groups in the U.S. and Latin America. Further research has helped flesh out its strengths and areas for potential sharpening: For presaging first-attempt failure, it showed a sensitiv- ity (true positive rate) of 80%, specific- ity (true negative rate) of 43%, positive predictive value (the probability subjects with positive screenings truly have difficult airways) of 19%, and negative predictive value (the probability subjects without positive screenings truly don't have difficult airways) of 93%. That's a strong NPV, but "overall test characteristic performance was moderate," investigators found. 2 Fortunately it's built to evolve. "The tool is meant to change every five years," Olvera says. "Say we learn that neck mobility is a huge issue. So we'll learn to combat that, whether we do inline stabi- lization or move the anterior part of the c-collar, or whatever we do. Then it may not be one of the main predictors any- more, so we can take the N out and put something else in. Say we find saturation becomes an issue—we just can't maintain our saturations appropriately. Then we can call it HEAVES. "It's made so that every five years or so, as we improve practice, we can improve the mnemonic and make it more applicable to current issues and standards." The Role of Video The familiar mnemonic for predicting a difficult intubation is of course LEMON (look externally, evaluate using the 3-3-2 rule, Mallampati score, obstruction, and neck mobility; some add S for saturation). The problem with LEMON in the field is that LEMON wasn't meant for the field. It was designed for the operating room and migrated outward. In an EMS setting it has drawbacks. Obviously, 3-3-2 evaluations HEAVEN combines six key attributes that can help crews determine the likelihood of a difficult airway.

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