Beyond the Basics: The Art of Critical Thinking Part 2

CEU Review Form Beyond the Basics: The Art of Critical Thinking Part 2 (PDF) Valid until July 2, 2008

PART 2
     Critical thinking and critical decision-making are some of the most popular buzzwords in EMS today. While the words may be spoken and the skills desired, application of the principles is significantly more challenging. This second part of the critical thinking series provides case-based examples and insights into integrating the process into your clinical practice.

CASE #1
     You are called to a man with an altered mental status. You arrive to find a 67-year-old in bed in his pajamas. It is 8:30 a.m. He responds to questions slowly but accurately, without noticeable slurring and after long pauses. His wife reports he was "absolutely fine" last night. He has no complaints, but seems a bit short of breath.

     Rule #1: Assess and treat for life threats before anything else.

     The patient is breathing adequately and without obstruction. You place him on 3 liters of oxygen via nasal cannula.

     Your history reveals a patient with a history of anxiety and prostate cancer. He had a radioactive seed placed in his prostate three weeks ago. His medications include Xanax (for anxiety) and Halcion (a sleep aid).

     The concept of critical thinking involves a differential diagnostic process. This case poses a wide-open field of potential causes. Using the possibilities-to-probabilities approach, the next step is to develop a list of possibilities. The list should be wide, but practical. Before reading on, develop a list of possible causes for this patient's altered mental status.

     Developing an accurate and inclusive list is a key component of the differential diagnostic process. If the patient's condition isn't on the list, you will eventually find it, but only after striking out and creating a second (or third) list.

     Rule #2: Develop an accurate list of differentials based on the patient's complaint and your knowledge of the pathophysiology of relevant causes.

     After stating Rule #1, we must advise caution in regard to reaching too far into the list of possible conditions. In EMS there are some conditions for which we do not have diagnostic capabilities or field treatment options. There are also things known as "zebras" in medical diagnosis. This leads us to Rule #3.

     Rule #3: When you hear hoofbeats, look for horses, not zebras.

     This medical axiom tells us there are a lot of things it could be, but a smaller list of things it may likely be. Developing a differential diagnostic list is a combination of skill, knowledge and judgment. Practice will help you home in on the proper balance.

     What was the list of differentials you created for this call? While the list will vary from clinician to clinician (review last month's article to determine if you are a clinician or a technician), a list developed at the scene of this real call included:

• Stroke or intracranial bleed/lesion
• Diabetic emergency
• Cardiac condition
• Pulmonary embolus
• Sepsis
• Shock (hypoperfusion)
• Respiratory cause
• Seizure.

     Some of these are a stretch, but nothing on the list is clearly impossible or out of the question. The process continues with additional history gathering, physical examination and vitals. The goal is to rule out conditions until a field diagnosis comes into view.

     Vital signs are obtained concurrently with the initial history. The vitals reported to you are: pulse: 88 and regular; respirations: 24; BP: 112/64; pupils: PERRL; skin: warm/dry; SpO₂: 96%; temp: 99.3ºF.

     While presenting this approach at conferences around the country, we are often asked, "Doesn't this take up too much scene time?" Our answer is "No." Most of these assessments should be done at some point during a call anyway. The difference isn't in taking additional time, but adding the correct differential diagnostic thought process to what you already do.

     There are tests we can perform for many of these conditions and historical questions we can ask to help focus on remaining items in the differential. Looking at the items in the differential, Table I describes field diagnostic procedures to either include or rule out each item.

     The items in this list are, for the most part, checked routinely. It is the perspective of true differential diagnosis that differs. In last month's article, we discussed the loop between clinical reasoning, clinical decision-making and critical thinking. An active investigation process may rule some conditions in, rule others out and introduce new ones into the mix. This process is not unidirectional; rather, it is a fluid, dynamic process with some back-and-forth that leads to solid clinical decisions in the field.

     The results of the history and physical examination are: Cincinnati Prehospital Stroke Scale: negative; blood glucose: 94 mg/dL (last oral intake was 8–10 hours ago).

     The patient denies chest pain and dyspnea on exertion, shows no pedal edema and no history of recent immobilization. Lung sounds reveal slight, scattered wheezes throughout with adequate lung expansion and breathing. EKG shows a regular sinus rhythm without ectopy. A 12-lead ECG does not reveal evidence of ischemia or infarct.

     You are unable to check medication amounts because they have been placed in a different container, but patient/family deny accidental or intentional overdose, and a significant quantity is present.

     A second set of vital signs is unchanged from the initial set. There is a slight increase (+/- 10 beats/minute) in pulse when standing, with some weakness. The patient denies dizziness when standing.

     While we may have tentatively ruled out some conditions, additional information would be helpful.

     Rule #4: Consider onset, fever and risk factors.

     Some field clinicians already consider these. Many don't. These are key elements in the differential diagnosis and are given high priority in the hospital. Have you ever noticed how quickly a patient gets a thermometer stuck in his mouth (or ear) after arriving in the emergency department?

     Onset. Conditions that usually begin with a sudden onset include asthma and spontaneous pneumothorax. Conditions with a more gradual onset include pneumonia and COPD exacerbation. Sometimes, patients believe it was a sudden onset, but it actually came on over time. A classic presentation of congestive heart failure is a patient in the middle of the night, sitting with his legs dangling over the side of the bed and gasping for air. He will report this as a sudden onset. A careful history will likely reveal weight gain, dyspnea on exertion and increasing orthopnea building over a period of days or weeks.

     Being alert for the onset of the patient's condition will help include or exclude items from your differential diagnosis. This is a key example of matching your knowledge of pathophysiologic principles to patient presentations to aid in diagnosis.

     Fever: We should routinely check each patient for fever. In this patient, there are obvious benefits. For other patients, like one in respiratory distress, the benefit may be in the surprise you get when identifying fever, which may change your perspective, diagnosis and ultimately your care.

     Risk factors: For many EMS providers, finding a history of diabetes, high cholesterol, hypertension or smoking simply means items to note on the run report. In fact, these findings are also risk factors for myocardial infarction or stroke and should provide a slight, yet significant, tilt toward a more serious condition in our diagnosis. Risk factors do not guarantee a condition is present, but they should be noted and given proper perspective.

     Obesity is another example of a chronic condition that leads to more serious health problems. Obesity should be considered a risk factor for myocardial infarction, stroke and diabetes.

     Returning to the case study, we have a man with an altered mental status with a relatively sudden onset, although it could have happened very suddenly or developed overnight. The Cincinnati Prehospital Stroke Scale appears to have taken stroke off the list. His blood glucose is within normal limits and rules out a diabetic condition. Table II applies findings to the differential diagnosis.

     It is not the purpose of this article to tell you there will be a conclusive diagnosis on every call. In fact, field diagnosis (sometimes called presumptive diagnosis) is what we use to develop a treatment plan. Not all conditions have treatments at this time. However, if we are able to narrow this down, even to simply make appropriate notifications (e.g., stroke center or cath lab), this may be the most valuable care we can give the patient who needs it.

     In this case, which may have evolved to a simple transport of an older patient with an inconclusive treatment, or could have resulted in a false diagnosis of a respiratory problem or overdose, a proper presumptive diagnosis was obtained.

     We propose to you that the true challenge isn't in treating the patient, but in EMS reaching the correct diagnosis. Once you have properly and accurately identified the patient's condition, the treatments are largely choices based on protocol (or in cases of co-existing conditions, protocols).

     Rule #5: The diagnosis won't always hit you over the head. You have to work for it.

     In this case, we don't have reason to believe we have a cardiac problem, stroke, diabetes, seizure or PE. Certainly nothing we would treat for. We did get some slight positives in that wheezes were present, his pulse and respirations were elevated and he had a slight fever.

     Rule #6: Don't chase your tail over nonsignificant findings.

     Corollary to Rule #6: Make sure you know what is significant and what is not. In this case, the most significant finding may be the elevated pulse and respirations for a patient at rest. Some may consider a pulse of 88 and respirations of 24 "normal," but they aren't. This is a key piece of information. Slight, scattered wheezes are most likely a distraction, even though we can treat wheezes. The key question is how the wheezes affect the patient's overall picture. Certainly not enough to treat them.

     Rule #7: Consider co-existing conditions.

     Be open to the fact that there may be more than one condition. In the COPD patient, we look for signs of exacerbation. We should also be probing for a history of the older respiratory infection that caused it. We don't always ask about the increasing productive cough, malaise, fever and other signs of infection that led to the exacerbation days or weeks before the call.

     Rule #8: Accept ambiguities.

     Use your knowledge of pathophysiology as the tiebreaker, which can be a guide in this situation. And this leads us to the answer: sepsis (or bacteremia).

     The most common initial presentation of sepsis is altered mental status. The old teaching of "septic shock" led us down the wrong road. Patients don't have signs of shock initially, and, in many patients (especially the elderly), raging fever isn't the norm. The patient we see in this case has a classic initial presentation of sepsis: low-grade fever and altered mental status.

     But where is the smoking gun? Sepsis is most commonly preceded by pneumonia or urinary tract infection. Recall the radioactive seed placed in the patient's prostate three weeks ago? By asking about urinary frequency and volume (something the pathophysiology of sepsis would have prompted you to do), the patient would have indicated frequent trips to the bathroom overnight with scant urine, and would have provided a sound basis for putting sepsis at the top of your differential diagnostic list. Indeed, possibilities have evolved to a true probability.

     Rule #9: Follow up on challenging patients to check your diagnosis and treatment. It will help hone your critical thinking skills.

OBJECTIVES

• Discuss the process of differential diagnosis
• Review how to apply the differential diagnosis process in the field

CRITICAL THINKING IN TRAUMA
     While the concept of critical thinking and differential diagnosis is sometimes thought of as a medical process, critical thinking processes are as important in trauma as they are in medical patients.

     The difference is that the treatments we can provide are somewhat fewer in trauma patients (transport to an appropriate facility being paramount), but nonetheless important. While we are sometimes faced with critical decisions, such as whether to decompress a patient's chest, the big picture decision remains identifying criticality, especially latent criticality, in the trauma patient. A case in point:

CASE #2
     Your ambulance is called to a motor vehicle collision in which a car has been t-boned while making a left turn. You are presented with three occupants between the two cars. Two are reporting injury. After a scene size-up, with requests for an additional ambulance and personnel, your triage leads you to an approximately 20-year-old female lying on the ground. She was the restrained passenger who took the impact directly into her door.

     Trauma Rule #1: Initial decisions are based on mechanism of injury.

     You note between 12–15 inches of intrusion into the passenger space. Your knowledge of anatomy helps you realize this pushed perilously close to her liver. Your initial assessment reveals a rapid pulse and respirations. Your crew administers oxygen and gets vitals while you perform a rapid trauma exam. Your exam shows no signs of injury (denies pain, adequate respirations without chest pain or tenderness, abdomen soft and non-tender, no bone or spine injury noted). The patient is upset about the crash, but she is rational and not anxious.

     Vital signs are reported as: pulse: 124 and regular; respirations: 28, BP: 118/68; PERRL; skin cool and dry.

     Trauma Rule #2: Your most important actions may be to determine criticality and make an appropriate transport decision.

     Most would agree that, even in the absence of obvious injury, the index of suspicion for internal trauma is high, based on mechanism of injury and vitals. The patient gets a collar and is boarded and moved to the ambulance for prompt transport.

     Clinicians know there is another possibility. When faced with the realization of almost being killed, the patient could simply be excited. Her vitals could return to normal. In this real-life situation, there was a regional hospital 10 minutes away and a trauma center an additional 20 minutes past the regional hospital.

     En route, the crew calmed the patient and took another set of vitals. Pulse and respirations were still high, blood pressure and skin the same. The patient seemed a bit calmer, but without a corresponding drop in pulse and respiration. Since this re-evaluation didn't change the suspicion, a choice was made to go to the trauma center based solely on MOI and vitals as a precaution—even in the absence of obvious injury.

     The patient was delivered to the trauma center without significant change in vitals. She was not injured and was discharged from the ED after a period of observation.

     In this case, understanding the pathophysiology of trauma led us to believe occult internal injuries were possible, and we transported to the trauma center as a strategic and wise precaution.

CEU Review Form Beyond the Basics: The Art of Critical Thinking Part 2 (PDF) Valid until July 2, 2008

SUMMARY
     This two-part series has addressed the critical thinking process both through discussion and demonstration in the case studies presented here. Indeed, the process involves all of the decisions we make in assessment and treatment. It is not limited to advanced providers. With the exception of the ECG analysis mentioned earlier, all other decisions were based on history and physical exam and can be performed by any provider. Thinking is not limited to a particular license or certification level. We hope these articles have helped you cross a bridge into stronger critical decision-making and farther along the journey of being a true prehospital clinician at any level of certification.

Daniel D. Limmer, AS, EMT-P, is a paramedic with Kennebunk Fire-Rescue in Kennebunk, ME. He is the author of several EMS textbooks.

Joseph J. Mistovich, Med, NREMT-P, is a professor and chair of the Department of Health Professions at Youngstown (OH) State University.

William S. Krost, BSAS, NREMT-P, is an operations manager and flight paramedic with the St. Vincent/Medical University of Ohio/St. Rita's Critical Care Transport Network (Life Flight) in Toledo, OH.

EMS EXPO
Joe Mistovich, Will Krost and Dan Limmer are featured speakers at EMS EXPO, October 15–17, in Las Vegas, NV. For more information, visit www.emsexpo2008.com.