BY MICHAEL D. SMITH
You have just completed transport of a 49-year-old male with stabbing chest pain and shortness of breath. Reviewing the run with your EMS student, you find him questioning why you felt the problem was not cardiac in nature. As you start to explain the differential causes for chest pain, he has a blank look on his face; the term “differential” seems lost on this student. You and your partner discuss the fact that many EMS students complete their classroom training without learning how to think during stressful times. Perhaps, more importantly, in less stressful circumstances not involving critically ill patients, many students are unable to assemble information presented into a working diagnosis that includes all of the possible differentials.
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Figure 1. |
You ask your student to list the differentials for chest pain. He answers, “heart attack,” and then stops. You ask if there is anything else. “I’m sure there is, but a heart attack will kill you faster than any other problem.” Your partner exhales loudly and walks away, shaking his head; you start to list a few differentials for your student: pulmonary embolism, thoracic aneurysm, dissecting aneurysm, and pericarditis. You inquire which of these differentials would kill a patient faster. The student is still confused and not sure what you are asking.
Critical thinking is a process that has been used in business and industry for a very long time. Many nursing programs have been teaching this form of information processing for years. Some of the best known critical thinkers in history include Carl Sagan, Isaac Asimov, Harry Houdini, and Albert Einstein.1 So what made these historic icons such great critical thinkers? They would research a problem or an idea to find all possible solutions and then investigate possible outcomes. Once they identified the entire range of outcomes, the legacy thinkers would then decide on the most appropriate solution for that particular problem.
In emergency medicine, clinicians don’t have the time to research each possible solution for every patient complaint, yet it is imperative to use good evidence-based protocols to direct our care. However, there are considerable risks of getting caught up in protocols by treating only signs and symptoms. The real concern is not thinking through the entire problem, including all possibilities for a patient’s complaint. Many technicians will pick a protocol algorithm and find reasons for the patient’s fitting into that algorithm. By ignoring new information or changes in patient condition, they can fail to switch gears and move in a different direction when necessary. A practitioner who lacks confidence in his assessment and critical-thinking skills will often hide behind the protocols and rarely ever develop into a good clinician. Critical thinking, sometimes referred to as clinical decision making, is a process in which the practitioner takes in information and processes it to develop a clear idea of what is happening with the patient. The more information the practitioner can collect, the better the chances that the conclusion he developed will be true and correct.2 With a good knowledge base and high-level assessment skills, a clinician will be able to use all of the clinical data and past medical history to come to a working diagnosis and establish patient care priorities.
Obviously, always start patient-care priorities with a good, clear patent airway and good ventilations, followed by good circulation. Without these very vital systems, it makes little difference what advanced critical thinking skills the practitioner may have; the patient will die. It goes without saying that the higher the acuity of the patient, the easier it is to set priorities and goals. The same goes for the patient of lesser acuity; not much thinking goes into treating these folks either. It’s the moderately ill or injured and the patient who does not match any textbook picture who requires the most critical thinking to develop an accurate picture of his condition and a proper care plan.
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Figure 2. |
You encounter an unconscious patient with hypotension; the priorities are very clear: airway, ventilations, and fluid. Critical patients do not require much critical thinking, and the clinical decisions that need to be made are easy. The same goes for the patient with a sprained ankle that occurred without a fall or loss of consciousness, minor swelling, good pulses, and motor sensory distal to the injury. Again, very simple—not much thinking here: splint and treat the pain.
Now let’s take the patient you transferred earlier in the day, a 49-year-old male with a recent diagnosis of diet-controlled diabetes and no other history. He awoke this morning and checked his glucose (143 mg/dl), ate a decent breakfast, and didn’t feel very well, so he went back to bed. The patient stated he felt tired and just lay around, pretty much sleeping the whole day. Now he complains of a stabbing pain in his left upper chest wall; feels slightly short of breath; and is cool, slightly moist, and pale. He also feels a little anxious. The patient tries to explain away all of these symptoms—he has been working too hard or strained something moving furniture and boxes around.
So what would the prudent clinician list as the primary field diagnosis? Chest pain/rule out myocardial infarction (MI)? Perhaps this could serve as a starting point. The prehospital community typically sees more MIs than any other chest pain etiology. Cardiac pain is generally thought of as crushing midsternal pressure, but it can be of a stabbing nature similar to what this patient is feeling. So what differentials fit with this patient and the primary working diagnosis? This is the point where critical thinking starts. A technician will just treat symptoms; a clinician will work through the differentials and find the cause of the symptoms.
ARGUMENT MAPPING
In business and industry, there exists a critical thinking mechanism called “argument mapping.” This technique allows for all aspects of a procedure or process to be reviewed. To start this process, you must identify a beginning and an end point. Then map out the entire process with all of the current options and possible new options for reaching the end. In the argument mapping process, all options are explored to make the process more successful and as streamlined as possible.3
Many EMS providers might think it is difficult or impossible to use argument mapping for assessing and treating a patient. In reality, until you become comfortable with the critical thinking process, it is best to write down your working diagnosis and then list possible differentials. Doing this will help direct your continued assessment and help you rule in or out all of the differentials listed. Argument mapping just became differential mapping and is a great tool to guide your patient assessment.
PATIENT: DIFFERENTIALS
If you use the acute myocardial infarction (AMI) as your working diagnosis, then you need to write down all of the differentials. The following differentials would be typical: pulmonary embolism, pericarditis, thoracic aneurysm, chest wall muscle strain, and pleurisy. Let’s map the complaints. How does the diagnosis of AMI fit with the symptoms? Well, there is chest pain and dyspnea, and the chest pain is stabbing in nature. Generally, crushing midsternal chest pressure is considered to be cardiac in nature. In the presence of a normal 12-lead electrocardiogram (ECG), the risk of cardiac etiology is slightly less likely (but certainly not ruled out). Along with very few cardiac risk factors, we can likely drop AMI as our primary working diagnosis.
Pericarditis generally presents with stabbing chest pain that increases with deep inspiration. The pain can be dependent on patient position and will often decrease or disappear completely when leaning forward. With pericarditis, a one-lead ECG will often demonstrate S-T elevation in all leads or leads that may not be congruent. If this patient’s 12-lead ECG shows no S-T segment changes, chances of pericarditis are less likely.
Thoracic aneurysm is generally thought to present when there is ripping posterior thoracic pain accompanied by unequal upper-extremity pulses and blood pressures. With no evidence of these symptoms, chances of this being a dissecting thoracic aneurysm are probably the least likely to be true. Chest wall muscle strain usually is reproducible, but so are many other types of pain. Although this may be an unreliable assessment tool, rarely does chest wall strain have associated dyspnea. Patients may complain of difficulty breathing on deep inspiration but are least likely to be short of breath if they have been sitting still. Pleurisy generally is associated with diffuse chest pain, not point-stabbing chest pain. This leaves us with pulmonary emboli.
Pulmonary embolism usually presents with stabbing chest pain, dyspnea, and anxiety. Depending on the size of the clot and its location, the symptoms may be more or less severe. Although pulmonary emboli are often associated with long-distance travel, sedentary lifestyle, use of oral contraception, and smoking, it is important to note that four in five patients have no risk factors.4
Let’s review our patient’s symptoms: stabbing pain in his left upper chest wall, slightly short of breath, skin cool, slightly moist and pale, and feeling a little anxious. Through differential mapping, we have decided this patient is most likely to have a pulmonary embolus. Using differential mapping, we were able to direct questions and assessments toward the pulmonary embolism. By having a better idea of what might be causing the patient’s symptoms, a clinician can dig deeper into past and more recent histories. This case demonstrates the use of critical thinking and differential mapping to develop a clearer picture of this patient’s situation. Obviously, it would be much easier to identify this case had the patient been cyanotic, extremely dyspneic, and acutely anxious. Acute illnesses are often obvious and require little in the way of critical thinking.
Good clinicians choose to think critically every day. Clinicians who are successful critical thinkers don’t just use these skills while on the job; they use them also in their daily routines. A good critical thinker in terms of knowledge, abilities, and attitudes has habitual ways of behaving and will likely use problem-solving techniques in common tasks.5
As you become a better critical thinker, you’ll add techniques used in assessing patients in your daily life. Critical thinkers determine the closest exit door when flying to eliminate the confusion of trying to locate an exit in an emergency. An anonymous survivor of United Flight 232 said, “Survival is up to me; no one likes me more than I do.” Critical thinking used on a daily basis can be worth all of life’s trials and tribulations in a single moment. Without it, that one life-changing moment will likely be lost.
Without classroom-taught skill sets, a technician learns to perform at a minimum standard. Using critical thinking, a technician will slowly become a clinician. Critical thinking allows prehospital providers to perform at a higher standard and have far greater impact on their patients. At the end of your conversation, the visiting EMS student has a better understanding of how each complaint he encounters throughout his career could be caused by many different conditions. This is one of those life-changing moments for this student. He will go home and study critical thinking and argument/differential mapping and become the inner clinician he may not have become prior to this field clinical experience.
Endnotes
1. “Ten Outstanding Skeptics of the Century,” Skeptical Inquirer; 1999:1214, http://www.csicop.org/articles/19991214-century/).
2. Paul, R and L Elder, “The Role of Socratic Questioning in Thinking, Teaching, & Learning.” Foundation for Critical Thinking, May 1996.
3. What is Argument Mapping? Critical Thinking on the Web, http://austhink.com/reason/tutorials/Overview/what_is_argument_mapping.htm).
4. Carson, JL, MA Kelley, A Duff , et al, “The clinical course of pulmonary embolism,” N Engl J Med, May 7 1992;326(19):1240-5.
5. Teaching Thinking Skills, Theory and Practise. J B Baron and R J Sternberg, eds, (New York: Freeman) 1987.
MICHAEL D. SMITH, NREMT-P, EMSI, CCEMT-P, is a firefighter/paramedic with the Grandview Heights (OH) Division of Fire, a flight paramedic for Medflight of Ohio, an Outreach critical care educator for Grant Medical Center’s LifeLink, and the coordinator for the EMS education program at Ohio University-Lancaster. He has been involved in EMS since 1986.
