This chapter was reproduced from the Emergency Medicine Clerkship Primer, 2008, Chapter 11, with the permission of the Editor, for ease of viewing on mobile devices.

While focusing on your “plan of action” (diagnostic evaluation and therapeutic intervention), it is necessary to realize that in many emergency department patient encounters, care is provided in a roundabout fashion. Because of the urgency of patient presentations, we do not always have the luxury of providing care in a structured manner the same way as in a low-acuity outpatient setting. Almost every shift, we evaluate patients with head trauma, acute respiratory distress, altered mental status, and many other complaints that require the care provider to make certain critical decisions early on in the evaluation, many times before a comprehensive H&PE is completed.

The evaluation of a “sick or potentially sick” patient cannot be performed in series; care must be provided in a parallel fashion. At times, the ordering of select diagnostic studies or the need to initiate therapeutics is evident immediately. The overall plan, including the speed and order of implementation, will be dictated by your concern for the patient’s well-being. The case study on the next page provides an example of providing parallel care in an emergency department setting.

Some patients that you encounter will be straightforward and nonurgent in nature. For these patients, you have the luxury of time. A focused H&PE can be performed. A problem list and differential diagnosis can be developed. A few minutes can be spent reviewing the medical literature about a certain aspect of the patient’s presentation. However, decisions need to be made, some after careful consideration and reflection, others immediately. For each patient you encounter you need to ask yourself, “What needs to be done for this patient?” and “What needs to be done now?” Every patient is different. Some cases are not urgent, allowing decisions to be made in a sequence that permits observation or the response to therapy to guide further care. Other cases are urgent or emergent and require immediate action.

Knowing if a patient is “sick or potentially sick” can many times be determined from the doorway, but sometimes it is not immediately clear. Certain findings, however, should be alarming: confusion; diaphoresis; cool, clammy skin; abnormal vital signs; and sudden severe pain are just a few clues that your patient may be sick. If the patient appears sick or if you believe there is a possibility that they have a serious underlying condition (e.g., cardiac chest pain, shortness of breath, a cold extremity, focal weakness, sudden onset of severe abdomen or back pain), immediately curtail your evaluation and find your supervisor. If the patient appears sick or if you believe there is a possibility that they have a serious underlying condition (e.g., cardiac chest pain, shortness of breath, a cold extremity, focal weakness, sudden onset of severe abdomen or back pain), immediately curtail your evaluation and find your supervisor.

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Understanding the Meaning of Vital Signs

Make sure all vital signs have been taken, and repeat them yourself if needed. Abnormal vital signs may be one of the first red flags encountered when evaluating a patient. However, do not forget that the patients with “normal” vital signs may still harbor a serious underlying condition. Vital signs vary with age and have to be viewed in context with the clinical presentation. Although isolated vital sign measurements can be significant, a persistent trend can be much more revealing as to the seriousness of the underlying condition or response to therapy. Vital sign abnormalities in general occur as a response to a variety of systemic insults. Aside from cardiac rhythm disturbances (symptomatic bradycardia and tachycardia), a thorough evaluation may be necessary to identify the underlying condition responsible for the abnormal vital signs (e.g., dehydration, hypovolemia, infection).

Temperature

Oral temperature readings can be falsely low in patients with an elevated respiratory rate. Inquire about recent antipyretic (e.g., acetaminophen, aspirin, nonsteroidal anti-inflammatory medications) use, because these medications may mask a febrile episode. This may be especially important in an infant younger than 3 months of age whose entire workup may be based on whether he or she is febrile (temperature > 38ºC or 100.4ºF). Septic patients, particularly the very young and very old, may not mount a febrile response to an infection and may on occasion present as hypothermic. Central nervous system injury, drug abuse, adrenal insufficiency, end-stage renal disease, and thyroid disorders can also affect basal body temperature or temperature regulation.

Pulse

The heart rate (HR) must be interpreted with attention to the age of the patient, especially when caring for infants and small children. Tachycardia in one age group may very well be a normal finding, whereas in another, it may be pathologic. Conversely, a well-conditioned athlete may have a resting HR in the 40s. For adolescents and adults, the maximum sustained HR can be estimated with the following formula:

maximum sustained HR = (220 – age in years) × 0.85

Take, for example, two patients. The first is 25 years old; the other is 85 years old. Each has a HR of 140 beats per minute. As you can see, using this formula, an HR this fast is much more concerning in the elderly patient, regardless of the cause. The pulse also has to be taken in context with other vital signs. The HR increases by approximately 10 beats per minute for each degree Fahrenheit of temperature elevation above normal. In addition, patients taking medications that slow conduction through the atrioventricular node (β-blockers, calcium channel blockers, and digoxin) may not mount a tachycardic response to physiologic stress.

Respiratory Rate

Count the rate yourself with a watch. Not everyone has a respiratory rate of 20 beats per minute. Infants are commonly noted to be periodic breathers. For these patients, it is necessary to count the respiratory rate for 30 seconds to 1 minute to get a more accurate measurement. The respiratory rate tells only one side of the story and provides little information as to the oxygenation or ventilatory status of the patient. Close attention needs to be paid to the respiratory effort, including the presence of retractions, accessory muscle use, and adventitious breath sounds. Also remember that some patients will have pulmonary manifestations of systemic disease states resulting in tachypnea (respiratory rate > 20 per minute; sepsis, pulmonary embolism, diabetic ketoacidosis, lactic acidosis, and salicylate toxicity).

Blood Pressure

Do not confuse the concept of “stability” with normal blood pressure. Hypotension is a late sign of shock; this is especially true in children. In cases of class II hemorrhage (loss of 15%–30% blood volume), findings usually include tachycardia, tachypnea, cool clammy skin, delayed capillary refill, and a decrease in pulse pressure, yet the systolic blood pressure (BP) may be in the normal range. The decrease in pulse pressure occurs because of increased levels of circulating catecholamines causing an increase in peripheral vascular resistance, thus raising diastolic BP. These patients are in compensated shock.

BP readings as well as other vital signs such as heart rate also have to be taken in context with the age of the patient. In infants and young children, it is common for the normal BP reading to be lower than adolescents and adults. A formula for estimating the BP in young children is as follows:

BP = 80 + (2 × age in years)

In adults, elevated BP readings in the emergency department are as common as in the adult ambulatory population. Some of these readings are transient, reflecting the clinical scenario at hand, and do not necessarily indicate underlying hypertension. Rarely do isolated elevated BP readings need to be urgently addressed in the emergency department.

Orthostatic hypotension and orthostatic vital signs in general are used in the bedside assessment of patients with known or suspected fluid loss, syncope, intravascular volume depletion, or autonomic dysfunction. At times, the use and misuse of orthostatic vital sign measurements revolve around the misinterpretation of the results, confusion as to what actually constitutes a positive finding, and the technique used to determine the measurements. A more in-depth review of this topic can be found in Roberts and Hedges’ Clinical Procedures in Emergency Medicine (2004).

Pulse Oximetry

Sometimes referred to as the fifth vital sign is a simple-to-perform, accurate, noninvasive assessment of the oxygen saturation (SaO2). The SaO2 correlates well with the partial pressure of arterial oxygen (PaO2), the relationship being described by the oxyhemoglobin dissociation curve. Despite its many advantages, pulse oximetry monitoring has some limitations. Although it is a noninvasive measurement of oxygenation status, no information is provided regarding the ventilatory status of the patient. In cases of suspected hypercarbia, an ABG analysis should be performed to determine the partial pressure of arterial carbon dioxide (PaCO2). In addition, pulse oximetry measurements can be only as accurate as empiric calibration curves. SaO2 values less than approximately 75% to 80% may be inaccurate because they are commonly extrapolated from healthy volunteer control subjects.

The presence of both carboxyhemoglobin (COHb) and methemoglobin (MetHb) can have significant effects on pulse oximetry readings when present in elevated concentrations. In patients with elevated COHb levels, pulse oximetry typically overestimates the SaO2. For approximately every 1% of COHb, the pulse oximeter overestimates the SaO2 by approximately 1%. Because of light absorbance qualities, in the presence of high concentrations of MetHb, the SaO2 as measured by pulse oximetry will approximate 85%. When either of these conditions is suspected, it is recommended to check an arterial or venous blood sample using a co-oximeter. Other factors affecting pulse oximetry readings include bright ambient or infrared light, peripheral vasoconstriction, motion artifact, and dark nail polish. Lastly, because it is possible to have a delayed detection of an hypoxic event, do not solely rely on pulse oximetry to determine oxygenation status.

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Conclusion

This chapter represents a starting point from where you should approach a patient when you are formulating your plan of action. The attention paid to your primary survey and secondary survey, vital signs, and the gestalt of “sick versus not sick” will be crucial to guide your initial diagnostic evaluation and need for therapeutic intervention.

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Suggested Reading

• Roberts JR, Hedges J. Clinical Procedures in Emergency Medicine, 4th ed. New York, NY: W.B. Saunders; 2004.

This text provides a comprehensive review of commonly performed procedures in emergency medicine.