PARAMEDIC DIFFERENTIAL DIAGNOSIS FLOWCHART 

By Chuck Sowerbrower

[NOTE: Before reading, please download the Paramedic Differential Diagnosis Flowchart - PDF 39.3KB]

Teaching critical thinking is one of the most important challenges facing educators. We strive to create “thinking” paramedics, not simply skilled technicians who blindly follow treatment protocols. The Paramedic Differential Diagnosis Flowchart is designed to help illustrate the thought processes involved in creating a valid “field impression” and then guiding correct treatment decisions for patients.

As the EMS provider begins to assess a patient, vast amounts of information need to be processed. Data are gathered from myriad resources, including environmental observations, a scene size-up, patient complaints and comments, such as the past medical history, medications and allergies, and information provided by others at the scene. Judgments are then made about each datum (piece of information), evaluating each for veracity (truthfulness), importance (significance), reality, and reproducibility. The EMS provider then assimilates all the information to form a field impression. The process is highly complex, even when the assessment seems to “appear instantly” as a very simple intuitive impression. Collected information about a patient can have differing levels of significance, depending on the context of the situation and the final impression. For example, a Chief Complaint of a Headache is very important when evaluating a patient for a Transient Ischemic Attack (TIA) or Cerebrovascular Accident (CVA), but a Headache may have almost no significance with a Chief Complaint of prolonged dull heavy chest pain that radiates to the left shoulder and jaw, suggesting a possible myocardial infarction.

The Paramedic Differential Diagnosis Flowchart is designed to handle various levels of clinical complexity and it can be used in several settings within the curriculum. One of the most valuable applications of the Flowchart is how it facilitates the integration of information. Further, as the program nears completion, the flowchart can be used to evaluate final performance competence. Last, the Flowchart can be a valuable aide for students to prepare for the National Registry Practical Examination Oral Station.

UTILIZING THE FLOWCHART

The first step in correctly using the Flowchart is ensuring that all instructors fully understand the goal and objectives for the lesson. The instructors then need to appreciate that the Flowchart is intended to discover the depth and complexity of each student’s comprehension and understanding about the patient scenario. In the beginning of the paramedic program, the depth and complexity of student knowledge are generally quite limited. However, when the Flowchart is used for paramedic refresher courses, experienced practitioners have a far greater breadth of knowledge and comprehend a great deal more about the complexities of scenarios. The progression from novice to expert is natural and readily applied with this tool. Scenarios that are too complex too early in the educational cycle will only confuse and frustrate students. Scenarios that are too easy late in the cycle will irritate and bore students.

Once the faculty understands the overarching goals of the activity, scenarios must be developed. The Flowchart is an open-ended tool that can readily move the scenario into areas the instructor is not anticipating. Depending on the sophistication of the students, it may be desirable to have the students create scenarios. This tool is suitable for large or small group settings. To allow for a timely creation of scenarios, it is advisable to have no more than four students work together to create each scenario. Working in small groups encourages active participation and results in a deeper understanding of anatomy, physiology, pathophysiology and treatments among all the participants. Once the drafters of the scenarios are ready to begin, have them draw the PATIENT ASSESSMENT ZONE (see figure 1) on a dry eraser board. It is important to construct the grid as part of the conversation as opposed to using a completed grid and simply filling in the information. It is important that the students experience the actual creation of the grid.

Once the scenario is developed, have the student(s) ask questions to gather the information. Write the information in the central box. If the faculty is in the role of the patient, then answer scenario questions as closely as possible exactly how patients would answer. For instance, the instructor should only provide information that is directly asked. Thus, if the student asks, “Did you have dinner?” The answer would be “Yes” or “No,” and not “I had roast beef.” If the students are new to this process, then provide an assessment structure for them by suggesting that they follow well-known mnemonics, such as SAMPLE, OPQRST, SOAP and other assessment tools. As the students discover new information about the patient in the scenario, have them place that information in the correct sections of the Flowchart. There are many formats for assessment that can be placed in the PATIENT ASSESSMENT ZONE. The use of a head-to-toe by body systems approach provides good organization of the information into meaningful categories. EMS educators may certainly use other formats.

More advanced students can write the information they collect as they gather it in any order. The purpose of this is to reinforce the principle that a structured assessment process yields a more reliable result. Thus, with the advanced students, you would be allowing them to discover that a haphazard assessment leads to confusion.

Once the data gathering and overall assessment are completed, the analysis of the information begins. Have the students draw a box around the PATIENT ASSESSMENT ZONE. The surrounding box is the IMPLICATION BOX (see figure). With every piece of information collected, there are implied circumstances that must be placed, for the information to be valid. Therefore, the next step is for the group to discuss the implications of each piece of information just gathered. For example, a patient who has a complaint of chest pain must have had an airway to speak. The purpose of this section is for students to understand that all of the data gathered rests upon the shoulders of implications below it. A person who is walking must have a blood pressure of at least 50 mm Hg systolic. Even if the BP is not stated, or measured, in reality, we know that the patient must have an adequate blood pressure to supply sufficient blood to the brain for the patient to be walking.

EXERCISE CAUTION

The faculty need to be cautious and students require guidance. The implications could go on indefinitely, stalling the process as the session deteriorates into mockery. There is no intention to imply that every imaginable possibility exists. This phase of the Flowchart tool is designed to help manage probabilities appropriately and make good critical thinking judgments about the possibilities! Based on a firm understanding of anatomy, physiology, pathophysiology, and age-related changes, the EMS educators, and eventually the students, should be able to filling in and appropriately consider reasonable implications of the assessment data. Again, a large percentage of the allowed time should not be devoted to this phase of the exercise. If the group begins to move more and more stray, then simply conclude this phase and move to the next step.

DEVELOPING FIELD IMPRESSIONS

Once the patient assessment is understood, the students need to create appropriate FIELD IMPRESSIONS (FI). Depending upon the scenario and the sophistication of the student, one scenario could generate only one or two possible impressions or it could generate multiple impressions, possibly 15 or more. It is a good idea to encourage limiting the possibilities to ensure a reasonable discussion. While developing the FIELD IMPRESSIONS, a RULE IN/RULE OUT step is applied to all of the data. To accomplish the RULE IN/RULE OUT step, expand the chart fields, leaving room for each FIELD IMPRESSION. Then chose one of the impressions and ask the students what information gathered RULES IN that impression? With each piece of information, have the students select a POWER RATING of the data in reference to this field impression. The POWER RATING provides an impression of the veracity, importance, and reproducibility of each piece of the data. This leads students to an understanding of how assessment data interact. An example would be analyzing a patient with shortness-of-breath. If one of the field impressions is Chronic Obstructive Pulmonary Disease (COPD), then the pulse oximetry reading would be a valuable piece of data. In the same scenario, the pulse oximetry reading would be meaningless when discussing the possibility of carbon monoxide poisoning. Have the students repeat this process of evaluation for the rule out data and apply the POWER RATING to each RULE OUT data element. Once a FIELD IMPRESSION is complete, repeat the RULE IN /RULE OUT processes with the POWER RATING for all of the FIELD IMPRESSIONS.

APPLYING CRITICAL THINKING

The next step is for students to critically analyze all of the information to determine which field impressions are reasonable, appropriate and applicable for the scenario. Have the students conduct an OVERVIEW of the field impressions and have the student make a POWER RATING for each field impression. This involves a good discussion of all of the RULE IN / RULE OUT information. As with real patients, the way to determine if a field impression is reasonable is the constellation of findings. The student should not focus simply on the field impression that has the most RULE IN findings. The POWER RATING of each finding has to be taken into consideration as do the any RULE OUT findings.

As with real patients, the paramedic needs to examine the patterns that remain and discuss TREATMENTS. If there is one impression that has a strong power rating and the others are weak, then the conclusion is rather simple – move toward that impression with the exclusion of the others. Outline the treatments that would be appropriate for that impression. If more than one impression has similar power ratings or there is no clear stand out, then a more cautious approach is appropriate. In these cases, underline the treatments for all of the impressions that are still reasonable. Then examine the treatments and chose to implement ONLY those that would not conflict with each other. For example, if shock is the primary FIELD IMPRESSION, but there is doubt as to whether the etiology is neurogenic, cardiac, septic or hypovolemic, the administration of electrolyte fluid volumes and the administration of drugs, such as dopamine, would have to be considered very carefully.

When using the Differential Diagnosis Flowchart in the classroom or laboratory, there are several teaching focal points to consider. The EMS Educator needs to reinforce the principle that the patient assessment provides the foundation upon which all patient care rests and all EMS educators need to continually redirect our students back to this foundation. We accomplish this through continually stressing the importance of a systematic, consistent and valid assessment process. The trauma patient mantra applies here: If you can not find it, you can not fix it. Encourage all students to directly visualize the entire body when assessing major trauma patients, ideally removing all clothing to assure full visualization. We can assess patients through their clothing, but that leads to missing occult injuries. Likewise, with medical patients, if we do not dig into the patient’s background on many levels, we will miss key facts needed to make a correct field impression.

The faculty needs to demonstrate the effects of gathering too little information. If the students do not perform a detailed assessment, then show them how the scenario can easily lead to 15 or 20 different possible field impressions. With so many possible field impressions, the only common denominators regarding possible treatments are Airway, O2, IV, Monitor and Transport. That is how weak paramedics perform, ones that are not thinking critically They choose the safe approach. They never really treat the patient; they only do the absolute minimum amount of thinking!

Do not require all your scenarios to have concrete conclusions. Many patients that are cared for by paramedics arrive at the hospital without a clear field impression. Certainly a competent paramedic has ruled out many options, but the assessment information available may not lead to one clear field impression. New students are more likely to want direct connections between assessment and field impression. Students with more knowledge should be able to handle some degree of ambiguity.

Finally, advise caution. As more information becomes available, then the grid needs to be reexamined to see if the new data changes any impressions. The student needs to understand how being leg “down the garden trail” can happen so easily. The FIELD IMPRESSION of any patient is only as good as the assessment information it is based upon. If new information is obtained, the prudent paramedic will always reassess the patient.

SUMMARY

The Paramedic Differential Diagnosis Flowchart was created as an attempt to systematize the complicated and, at times, contradictory nature of medicine. Students who utilize the Flowchart will be able to see first-hand how assessment and interpretation interact to lead to appropriate field impressions. Ultimately, the process helps to create care providers who are prepared to manage the demands the most challenging EMS patients.

Chuck Sowerbrower is Chair of EMS Education at Sinclair Community College in Ohio.