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EMS Assessments & Differential Diagnosis


An EMS crew arrives on scene and finds a 70-year-old male with shortness of breath. They quickly place the patient on oxygen and begin to obtain a set of vital signs: pulse 110, blood pressure 100/86, respirations of 30. A review of the patient's medication reveals albuterol, Isordil, Hydrochlorothiazide (HCTZ) and prednisone. The patient admits to being a two-pack-a-day smoker for the past 50 years and isn't as active as he used to be. The EMT turns to his partner and says, "Looks like an exacerbation of emphysema. I think he needs a puff of his albuterol." The partner looks contemplative and says, "What if it's something else?"

Think Outside the Box
With the majority of calls in EMS, if it looks like a duck, walks like a duck and quacks like a duck, it's most likely a duck. We need to be careful, however, not to be lulled into complacency and routine, allowing us to miss something we didn't anticipate. In a profession based in mnemonics and algorithms, it's easy to skip the critical thinking component of medicine.

Divergent thinking is the consideration of many different possibilities. This process is great in marketing and business, but, in emergency medicine, it may lead the provider to too many "what if" questions that delay treatment. Convergent thinking, on the other hand, is focusing on only one solution. In medicine, this has been referred to as tunnel vision. Neither of these thought processes result in good patient care. Providers must begin with a limited divergent thought and then, through assessment, move toward convergent thinking, which leads to appropriate treatment. At the same time, the EMT must remain open to other possibilities.

With every chief complaint, establish at least three (but no more than four) possible causes for the patient's condition. This is known as creating a differential diagnosis. The differential should consist of a combination of the most critical and most common possibilities. In the opening scenario, an exacerbation of emphysema is definitely a possibility, but so is a myocardial infarction (MI), pulmonary embolism or pneumothorax. You can begin establishing a differential diagnosis as soon as you receive dispatch information.

Use the following "list of Rs" to help you perform a thorough assessment when you arrive on scene:

  • React to life threats
  • Read the scene and patient
  • Respond to your findings
  • Re-evaluate your treatment
  • Revise as necessary
  • Review your performance

The EMT must react to life threats. Airway, breathing and circulation always take priority after scene safety has been established. Place the patient on oxygen, open the airway, stop the bleeding or begin CPR as necessary. In critical patients, such as those in cardiac arrest, the EMT may never leave this reaction stage. Treatment for the most critical patients usually follows an algorithm and requires little decision making. Non-critical patients are similarly straight forward. Broken bones are splinted and cuts bandaged. It's the potentially critical patients that offer the greatest challenge to the critical-thinking skills of the EMS professional. These patients often have multiple disease processes or co-morbid illness.

After reacting to the life threats in the potentially critical patient, the EMT should consider their differential. Evaluate the scene, take a history of the current event and past medical history, and perform a physical exam to prioritize possible causes of the signs and symptoms. Determine the most likely cause. Before beginning treatment, determine if the patient can tolerate the side effects of the treatment. For example, is the blood pressure too low for nitroglycerine? Or, in the case of our patient, if he's having an MI, will an albuterol treatment help or hurt?

After assessing and evaluating options, a treatment plan can be established. Never assume the treatment plan is working perfectly. In fact, expect that the treatment plan will not be effective and anticipate what the patient will need next. This allows the EMT to stay one step ahead. Re-evaluate often. If the current treatment is working, then stay the course. If the selected treatment isn't effective, then re-evaluate the course.

Evaluate for new symptoms or changes in patient status. Be open to the possibility the initial impression was wrong. If so, change course and proceed with the new treatment. When in doubt, remember the basics and maintain airway, breathing and circulation. Contact medical control for consultation when possible.

After the call, the EMT should visit with the attending physician or their physician advisor. They should critically review their performance acknowledge mistakes made and avoid these mistakes in the future. Learn the patient's diagnosis and understand the what, why and how of the presentation. This information can be logged into memory banks and retrieved on future calls.

Working as an EMT requires a knowledge of anatomy and physiology, disease processes, and drugs within the prehospital scope that are used to treat diseases. An effective EMT must also have the desire to continually learn and improve. Never let a chance to learn something new pass by unstudied.


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