Undifferentiated and Differentiated Patients

This chapter was reproduced from the Emergency Medicine Clerkship Primer, 2008, Chapter 6 with the permission of the Editor, for ease of viewing on mobile devices.


The clinical environment of the emergency department is both challenging and exciting. Open 24 hours a day, 7 days a week, the emergency department can serve as both the point of first contact and the bastion of last resort for an incredibly diverse group of patients with differing and unexpected medical needs. Unique among medical specialties, the mission and charge of the emergency physician is to care for all patients regardless of financial resources, severity of illness, or even the nature of the complaint. Whereas other specialists focus on a particular body system or category of illness, the emergency physician must be prepared to treat patients across the spectrum of disease and age. Each patient represents a mystery, an unknown quantity for the clinician. It is the unwavering fact that anyone can come through the doors at any time, which presents us with one of our greatest clinical challenges: the undifferentiated patient.

Approach to the Undifferentiated Patient

When you first encounter a patient in the emergency department, you must make an instantaneous assessment of both the severity of the threat to the patient’s life and limb and the need for immediate intervention. This determination is often made within a few moments of your patient encounter; that is, is the patient sick or not sick? Sometimes this decision may be easy, such as the patient with a gunshot wound to the chest or a patient presenting in severe respiratory distress. Many times, however, the distinction between “sick and not sick” may be much more subtle. Consider the following cases: an 80 year-old nursing home resident with a fever; a 40 year-old patient with a history of asthma presenting slightly diaphoretic, breathing 35 times per minute; a patient presenting postictal after a new onset seizure. All of these patients may be critically ill and require immediate intervention, and the skilled medical student, resident, or attending must be able to recognize this. As a student, your primary role if you identify a “sick or potentially sick” patient is to immediately notify your supervising physician—you will see this as a recurring theme. In a patient with abnormal vital signs who appears stable, it may be appropriate to repeat the vital signs yourself and then notify your supervisor promptly if they remain abnormal.

Unique among medical specialties, the mission and charge of the emergency physician is to care for all patients regardless of financial resources, severity of illness, or even the nature of the complaint.

In determining the severity of a patient’s illness and the need for immediate intervention, the emergency physician relies on a combination of clinical experience and instinct, integrating all of the available information into his or her decision-making process. Findings that may indicate severe illness include abnormal vital signs and an alteration in mental status (depressed level of consciousness or agitation). The astute clinician should recognize these findings as indicative of a potentially life-threatening condition and should act on them promptly. Perhaps the most important measure of the severity of patient illness is physician “gestalt,” that is, the gut instinct that something just is not right. This is one of the most important qualities a physician can develop.

Once a critical illness is identified, the physician must be prepared to act. In many cases, this means forgoing the natural progression from obtaining a medical history to performing a physical examination to formulating an assessment, and implementing a management plan. These cases often require the clinician to immediately focus the H&PE and jump right to case-specific management. Although the specific intervention will vary for individual patients, some general treatment principles should be followed. At times, you may hear your supervisor refer to the “emergency department safety net.” This term refers to the initiation of cardiac monitoring, obtaining vascular access, and providing supplemental oxygen if needed.

Be a Medical Pessimist

Don’t make assumptions until you have ruled out all high morbidity and mortality conditions. The classic example is the pregnant young woman who presents with abdominal pain. On the top of our differential list should always be ectopic pregnancy.

Assessing ABCDs of Resuscitation

As specialists in resuscitation, an emergency physician’s first priority is assessing the airway (A), breathing (B), and circulation (C), followed by an evaluation of neurologic disability. Ignoring deficiencies in one of these areas will inevitably lead to worsening of the patient’s clinical condition. Indications for emergency airway management may include hypoxia, hypercarbia, altered mental status, failure to tolerate oral secretions, and the anticipation of a worsening clinical condition. Remember, the ABCs are about much more than just intubation. In any ill patient, careful attention must be paid to oxygenation status, respiratory effort and pattern, and blood pressure and the presence of any neurologic deficit. In addition to evaluating disability, the “D” should always stand for measurement of serum glucose followed by administration of dextrose if a patient with an altered mental status is found to be hypoglycemic.

Addressing Abnormal Vital Signs

At the very least, if a patient has abnormal vital signs, vitals should be repeated and monitored closely. As a general rule, certain conditions (i.e., hypotension, severe hypertension with target organ damage, hyperthermia, hypothermia, bradycardia, tachycardia, tachypnea, and bradypnea) will require intervention and stabilizing measures initiated early in the course of their evaluation. These actions may include, but are not limited to, cardioversion of unstable tachyarrhythmias, supplemental oxygen, passive or active rewarming, or administration of intravenous fluids.

Findings of Potentially Serious Illness

  • Heart rate > 120 or < 60 beats/minute
  • Respiratory rate > 20 or < 10 breaths/minute
  • Systolic blood pressure < 90 mmHg
  • Temperature > 38 or < 35°C
  • Hypoxia
  • Altered mental status
  • Hypoglycemia or hyperglycemia


As a corollary, the effect of such interventions needs to be closely monitored. Remember, the underlying cause of all abnormal vital signs should be investigated. This axiom cannot be overstated. Vital sign abnormalities are often the result, not necessarily the cause, of a systemic insult. The investigation into the etiology of the abnormal vital signs should be delayed until stabilizing measures are initiated.

Treating Pain

An absolute tenet of emergency medicine practice is to treat the patients’ pain. Pain-related complaints are far and away the most common reason for patients presenting to the emergency department, with abdominal pain and chest pain being the two most frequent chief complaints. Together, these complaints represent more than 13 million emergency department visits annually across the country (Nawar, 2007). Not only is it morally imperative to provide analgesia, it is the right thing to do. Providing pain relief with an appropriate dose of an analgesic should not interfere with physical examination findings of peritonitis or accuracy of selected diagnostic imaging studies.

In determining the severity of a patient’s illness and the need for immediate intervention, the emergency physician relies on a combination of clinical experience and instinct, integrating all of the available information into his or her decision-making process.

Approaching the Stable Patient

Once the clinician is assured that the patient is stable, he or she should use a focused, systematic approach to evaluation and management. Paramount to this is obtaining an accurate history. It is important to allow the patient to provide the history in his or her own words. The use of open-ended questions allows patients to describe their condition and presenting complaints as they experience them. Examples of appropriate open-ended questions include the following: “What brings you to the hospital today?” or “How can I help you today?” Patients should be allowed sufficient time to describe their symptoms, while the clinician listens carefully for clues to the underlying diagnosis. After the patient has been given time to explain his or her complaints, the caregiver should ask appropriate follow-up questions to fill in any gaps. Although these questions are often open ended as well, a more directed inquiry may be necessary. The clinician should seek information that can help clarify the patient’s diagnosis or point toward an appropriate workup. Be a medical pessimist Never assume that a patient’s complaint represents a benign issue until all high morbidity and mortality conditions have been considered and sufficiently excluded.


Be a Medical Pessimist

Don’t make assumptions until you have ruled out all high morbidity and mortality conditions. The classic example is the pregnant young woman who presents with abdominal pain. On the top of your differential list should always be ectopic pregnancy.

Approach each patient, regardless of complaint, with a broad differential diagnosis, with the most serious conditions at the top of your list, that is, the “worst first” mentality. For example, always assume that chest pain could be caused by one of many potential life-threatening processes (e.g., acute coronary syndrome, pulmonary embolism, pericarditis, pneumothorax, pneumonia, aortic dissection, or esophageal rupture). Less serious diagnoses can be considered once these processes have been eliminated. This, of course, does not mean that every patient with chest pain requires cardiac enzymes, a CT scan, an ECG, and the like, but it is prudent to consider all high-risk diagnoses in each patient rather than rejecting them outright because of the patient’s age or an atypical presentation. By taking an accurate history and performing a focused physical examination, many of these differentials can be effectively excluded without an extensive workup. The healthcare provider can use the initial H&PE to narrow the differential diagnosis, focusing in on likely causes to guide the evaluation.

Keeping an Open Mind

It is important not to limit the differential diagnoses based solely on the patient’s chief complaint and presenting symptoms. Although this information is vital, limiting your differential diagnosis can be dangerous. Consider the elderly diabetic patient who presents with nausea and vomiting. Focusing only on gastrointestinal causes may delay the diagnosis of other potentially serious conditions such as diabetic ketoacidosis or myocardial ischemia. It is imperative to listen to the patient, but it is just as important at times to step back and think outside of the box. By keeping an open mind and not getting locked in, you will avoid the potential pitfall of honing in on a particular diagnosis before all of the information is available, also known as “premature closure.” Just as it is dangerous to assume a patient has a benign condition, it is equally wrong to jump to a diagnosis too quickly. Do not be afraid to change your diagnostic considerations as additional information or test results become available. When test results, or responses to therapy, do not fit with the presumed diagnosis, reevaluate the patient.


Following the Best Path

You can’t always walk a straight line; sometimes patient care follows a roundabout path. When evaluating the undifferentiated patient, it is not always possible to progress gradually from H&PE to diagnostics to treatment. Often it is necessary to perform two or more of these tasks simultaneously. In the critically ill patient, the emergency physician will often be deciding which diagnostic tests are needed while simultaneously conversing with, examining, and treating the patient. In addition, the response to an intervention may help guide additional testing strategies. A patient presenting with an exacerbation of asthma that improves with bronchodilator therapy might not require a chest radiograph or ABG, whereas a nonresponder might.

Differentiated Patients

Certain subsets of patients present a special challenge in the emergency department and deserve brief mention. Although a detailed discussion of these issues is beyond the scope of this manual, be aware of the inherent complexity in caring for these patients. Some groups of differentiated patients include the elderly, children, psychiatric patients, and the chronically ill. The differentiated patient can also present a diagnostic challenge for the emergency physician. An approach to these encounters should be performed in a logical and systematic fashion to avoid the pitfalls of a delay or misdiagnosis.

Elderly Patients

Elderly patients can present some of the most difficult diagnostic challenges for the emergency physician. This group is at high risk for a number of reasons. Life-threatening cardiac, pulmonary, vascular, and neurologic conditions are far more common in this population, and the elderly are more likely than the general population to have significant underlying health problems. Geriatric patients are often taking multiple medications, which may contribute to their presentation or may interact with prescribed therapies. They also have decreased physiologic reserves, which affects their response to critical illness or injury. Problems with memory in some patients can also limit your ability to obtain a clear history, further complicating the clinical encounter. In addition, the presentation of certain medical conditions (e.g., myocardial infarction) may be atypical, with vague, nonspecific symptoms actually being the harbinger of serious underlying illness.

In the elderly, a bacterial infection is not always associated with a fever or leukocytosis. This finding may inadvertently lessen the suspicion of an infectious etiology. Weakness and confusion are common presenting complaints that can represent a whole spectrum of disease, including infectious, cardiac, endocrine, and neurologic conditions. Finally, when working with the elderly, end-of-life issues may need to addressed with both the patient and the family, which can be a daunting task. When evaluating a geriatric patient, it is prudent to be both vigilant and conservative at the same time. Consider a broad differential diagnosis, keeping in mind that typical diseases may present atypically. Use as many sources as possible to obtain a medical history, including family members, past medical records, the primary care physician, or nursing home records, when applicable. When the history or symptoms are vague, or the patient is unable to provide detailed information, clinicians should have a low threshold for obtaining diagnostic studies.

The geriatric emergency department patient also presents a clinical challenge as this subset (65 years of age or older) of patients are sicker than the general population and represent the greatest percentage (41%) of hospital admissions of all age groups (Nawar, 2007). Finally, if an elderly patient is going to be discharged, it is important to ensure that he or she will have adequate social support and access to follow-up medical care.

When working with the elderly, end-of-life life issues may need to addressed with both the patient and the family, which can be a daunting task.


Pediatric Patients

As with the elderly, obtaining a history from a young child can be difficult. In preverbal children, the information must be obtained entirely from the parents or other caretakers. Even with older children, anxiety and misunderstanding can prevent the emergency physician from getting an accurate history. Remember, infants are at risk for serious bacterial infection, although the introduction of haemophilus and pneumococcal vaccines has significantly decreased this threat. In addition, be aware of the high prevalence of maltreatment and neglect in this population and consider abuse in all pediatric patient encounters.

Whenever possible, children should be examined with their parents present to minimize anxiety, unless the health care provider suspects abuse. The exception is adolescents, who may feel more comfortable discussing personal issues without their parents present. These encounters, however, should be chaperoned by an additional health care provider, preferably of the same gender as the patient.

Emergency physicians need to remember that children are not just little adults.

Emergency physicians need to remember that children are not just little adults. The spectrum of disease across the pediatric population is vastly different from that of the adult population. Seasonal variations of illness are more common, and clinical presentations of disease in infants and toddlers may be different as compared to adolescents and adults. The healthcare provider should be familiar with the different size and type of equipment required for pediatric resuscitation and medication doses as these also differ from adult patients.


Patients With a History of Psychiatric Illness

Patients with a history of psychiatric illness is another challenging subset of patients encountered in the emergency department. It is important to exclude organic pathology before attributing a patient’s presentation to a functional illness. Be a patient advocate, especially in these cases. In addition, many of these patients take medications that have a high likelihood of side effects and toxicity. Others are noncompliant, which can result in an exacerbation of their underlying mental health condition. Deciphering between functional and organic etiologies of patient presentations is challenging and not always straightforward.


Patients With Chronic Health Conditions

It is becoming more and more commonplace to encounter emergency department patients who have chronic health conditions such as ischemic heart disease, hypertension, diabetes, congestive heart failure, asthma, chronic obstructive pulmonary disease, depression, and end stage renal disease. These patients suffer from the same maladies as the general population but may at times be at higher risk for complications because of their chronic health condition or prescribed medical therapy. Approach even the stable appearing patient with a complex medical history with a degree of skepticism.

  • When caring for a patient with a complex medical history, be careful not to glance over details that might prove to be important. Consider the following:
  • As in all cases, initiate stabilizing care immediately if necessary.
  • In a stable patient, procede in a logical systematic fashion performinga focused yet thorough H&PE.
  • Spend time reviewing the past medical or surgical history to better familiarize yourself with the extent of the patients chronic health condition.
  • Review pertinent medical records and contact the patient’s primary care physician when indicated.
  • Consider whether the presenting complaint is related to or complicated by the underlying chronic health condition.
  • If the patient is presenting with an exacerbation of a chronic illness (e.g., asthma, congestive heart failure), try to place the severity of the current presentation in context with prior exacerbations.
  • Consider using risk reduction strategies such as medication reconciliation to prevent prescribing errors or adverse medication effects that can occur with patients on multiple medications.

Suggested Reading

  • Garmel G. Approach to the emergency patient. In: Mahadevan SV, Garmel G. An Introduction to Clinical Emergency Medicine: Guide for Practitioners in the Emergency Department. New York, NY: Cambridge University Press; 2005:3–18.
    • This chapter outlines some basic principles of emergency medical care.
  • Nawar EW, Niska RW, Xu J. National Hospital Ambulatory Medical Care Survey: 2005 emergency department summary. Advanced Data for Vital Health and Statistics. 2007; 386:1-32. Available at: http://www.cdc.gov/nchs/data/ad/ad386.pdf. Accessed April 26, 2008.
    • This article reviews nationally representative data on emergency department care in the United States. Data are from the 2005 National Hospital Ambulatory Medical Care Survey.
  • Wears RL. The approach to the emergency department patient. In: Harwood-Nuss A, Wolfson AB, eds. The Clinical Practice of Emergency Medicine. Philadelphia, Pa: Lippincott, Williams & Wilkins; 2001:1–4.
    • This chapter outlines some basic principles of emergency medical care.
  • Wrenn K, Slovis C. The ten commandments of emergency medicine. Ann of Emerg Med. 1991;20:1146–47.
    • This article highlights some basic precepts of emergency medicine.