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October 1, 2012

The transition from emergency care to the hospital

How many times have you delivered a patient to the emergency department and watched a nurse or physician replace your non-rebreather mask with a nasal cannula or gently remove your fully immobilized patient from the backboard?

Unlike with EMS protocols, which often take a shotgun approach to assessment and treatment, evidence-based medicine has for many years allowed nurses and physicians to target their interventions to the specific needs of each patient.

A key difference between hospital and prehospital care is reimbursement. Hospitals are reimbursed for patient outcomes while EMS is paid for services provided (primarily transportation), usually without regard to outcomes.

All indications suggest this will soon change.

When you consider the many interventions that you perform in EMS, you probably have trouble identifying which ones actually make a real difference in patient outcomes.

Continuous Positive Airway Pressure (CPAP) is one EMS treatment modality that has an evidence-based effect on patient outcomes. It has such an impact that more than once, hospitals have paid for EMS systems to acquire and use CPAP on their patients.

In 2008, a group of medical directors from Consortium of U.S. Metropolitan Municipalities (commonly known as the "Eagles" – see: published a consensus paper describing evidence-based performance measures for EMS systems1. This paper was the first comprehensive analysis of studies connecting EMS care to patient outcomes.

Using the best available evidence at the time, the authors developed a list of key elements for five clinical problems encountered by EMS: ST-Elevation Myocardial Infarction (STEMI), pulmonary edema, asthma, seizure, trauma and cardiac arrest. They researched EMS care proven to benefit patients using a statistical calculation called Number Needed to Treat (NNT).

NNT tells you how many patients you would have to treat with a specific intervention to prevent one bad outcome. If you consider the scope of treatments available in medical care, many have very high NNT values. For example, you would need to treat 210 patients with ACE inhibitors to prevent one death after an MI. The NNT for ACE inhibitors following MI, then, is 210 to prevent one death.

Interventions with a low NNT are considered more effective while those with a very high NNT may not be worth the cost. Prehospital CPAP for patients with pulmonary edema had an NNT of 6 to prevent one patient from needing endotracheal intubation2 at the time the Eagles paper was published.

Suffice it to say that an NNT of six for any intervention is a big deal. Preventing intubation is also a huge cost savings for hospitals, so much that many hospitals were willing to buy EMS services CPAP units in order to reduce their ICU admissions and total lengths of stay for patients with pulmonary edema.

If you are interested in learning what difference your EMS service makes to your community, evidence-based performance measures like the Eagles paper can help you crunch the numbers. For example, if your service used CPAP on 12 patients last year with pulmonary edema, the NNT of 6 tells you that you prevented two patients from being intubated.

This is important because not everything we do really does make a difference in outcomes, no matter how much you think it helps. NNT provides an objective way for you and your service to highlight the lives you have saved, the complications you prevented and the ultimate good you do for your community.

It also, as you might imagine, gets the attention of hospitals. Turn patients over to a hospital after starting an evidence-based treatment known to improve their long-term outcomes and shorten their hospital stay, and you will be amazed how much smoother the transition of care can become.

Although many states consider CPAP a BLS skill, experienced clinicians believe that successful use is also an art. No person with significant respiratory distress welcomes the sight of something being placed over their mouth and nose: They're having enough trouble moving air without having to breathe through a mask.

Selection of a CPAP mask is important and not a skill you can learn on the fly. Review the masks your service carries, and become familiar with proper sizing and placement so you can quickly achieve a good seal.

Communication is equally important. CPAP requires considerable coaching; you need to gain the trust of your patients and convince them that the CPAP will absolutely help them feel better. When a patient becomes increasingly restless and agitated with CPAP, your first thought should be that it's not enough to help them.

Consider increasing the delivered pressure. Watch their oxygen saturation, and, if you have capnography, use it to get a picture of how much air they are actually moving in and out of their lungs.

It may be necessary to assist ventilations with a bag valve mask. If you have a properly placed mask, you need do nothing more than connect a bag valve to the mask and begin ventilation.

Consider also that pulmonary edema is difficult to diagnose. Many patients we think have pulmonary edema turn out to have some other cause of their respiratory distress2. Not to worry: the prehospital application of CPAP has been shown not to hurt, and it often actually helps patients with this kind of respiratory distress1.

More recent data suggest that prehospital CPAP, when used for the whole range of patients with severe respiratory distress, has a NNT of 5 to prevent one death and an NNT of 3 to prevent one intubation3.

This more recent study demonstrated that prehospital use of CPAP could shorten hospital stays by an average of two days. That poses some significant bragging rights for EMS services that implement and successfully use CPAP. It also smoothens the transition of care between prehospital and hospital.

Finally, if you're up on the latest resuscitation science, you probably stay awake at night worrying about oxygen. In the absence of hypoxia (low oxygen saturations), oxygen does nothing to help patients with respiratory distress and is quite likely harmful.

Recognizing the potential dangers of oxygen (which is often used to power CPAP devices), Bledsoe and colleagues looked recently at whether CPAP could be safely delivered with less oxygen4. Indeed, it can. So your next mission may be to find an oxygen blender or a CPAP device capable of delivering only the level of oxygen your patient really needs.

That may be a challenge, but think about it: The reason hospital providers remove your non-rebreather mask is often because they know it is not helping and might well be hurting the patient you've just delivered to them.

If we put more science into EMS and pay attention to performance-based measures and values like NNT; we'll improve outcomes and be able to prove it. That will land us in just the place we need to be when insurers start reimbursing EMS as they pay hospitals: for outcomes, not for services rendered.

That day is coming. Will you be ready?


1. Myers JB, Slovis CM, Eckstein M, Goodloe JM, Isaacs SM, Loflin JR, Mechem CC, Richmond NJ, and Pepe PE. Evidence-Based Performance Measures for Emergency Medical Services Systems: A Model for Expanded EMS Benchmarking. Prehospital Emergency Care. 2008;12:141-151.

2. Hubble MW, Richards ME, Jarvis R, Millikan T, and Young D. Effectiveness of Prehospital Continuous Positive Airway Pressure in the Management of Acute Pulmonary Edema. Prehospital Emergency Care. 2006;10:430-439.

3. Thompson J, Petrie DA, Ackroy-Stolarz S, and Bradua DJ. Out-of-hospital Continuous Positive Airway Pressure Ventilation Versus Usual Care for Acute Respiratory Failure: a Randomized Controlled Trial. Annals of Emergency Medicine. 2008;52:232-241.

4. Bledsoe BE, Anderson E, Hodnick R, Johnson S, Dievendorf E. Low-Fractional Oxygen Concentration Continuous Positive Airway Pressure Is Effective In The Prehospital Setting. Prehospital Emergency Care. 2012;16:217-221.

About the Author

Mike McEvoy, PhD, NRP, RN, CCRN is the EMS Coordinator for Saratoga County, New York and a paramedic supervisor with Clifton Park & Halfmoon Ambulance. He is a nurse clinician in cardiothoracic surgical intensive care at Albany Medical Center where he also Chairs the Resuscitation Committee and teaches critical care medicine. He is a lead author of the “Critical Care Transport” textbook and Informed® Emergency & Critical Care guides published by Jones & Bartlett Learning. Mike is a frequent contributor to and a popular speaker at EMS, Fire, and medical conferences worldwide. Contact Mike at