EMS Clinical Diagnosis Without the Use of a Thermometer

Issues of Concern

Subjective assessment of elevated temperature and associated clinical findings is essential in EMS. Fever commonly produces nonspecific symptoms, including fatigue, subjective warmth, headache, malaise, anorexia, myalgias, nausea, and sweats or chills. Studies demonstrate that fatigue, subjective warmth, headache, and weakness occur most frequently during the febrile phase. The presence of at least 1 of these symptoms, combined with tactile skin temperature assessment, should raise suspicion for fever. Dehydration is rarely detected on initial examination in febrile patients despite correlation with the highest fever severity during the febrile phase.[8]

Pulse rate may increase in response to fever, dehydration, or shock. Pulse palpation provides an accurate rate and information regarding the adequacy of blood pressure and perfusion. An increase of approximately 10 bpm for each degree of temperature elevation helps determine whether tachycardia reflects fever or additional causes. Concern for severe infectious disease, particularly sepsis, should increase when tachycardia accompanies suspected infection. Shock can develop rapidly, and identification of infectious causes is necessary for definitive treatment. Patients receiving medications that affect heart rate, such as β-blockers and calcium channel blockers, may not develop tachycardia, so a normal heart rate does not exclude fever or infection.

Sepsis, particularly in older adults, can also produce bradycardia associated with end-organ failure. Endocrinologic abnormalities and toxidromes or withdrawal syndromes commonly present with pulse abnormalities corresponding to temperature derangements. Sympathomimetic exposure often produces suspected hyperthermia accompanied by tachycardia, tachypnea, and diaphoresis.

Respiratory rate may increase as a direct physiologic response to fever and decrease with hypothermia. Studies suggest that respiratory rate can increase by approximately 5 breaths/min per 1 °F elevation in core body temperature. Tachypnea warrants evaluation for respiratory distress, hypoxia, or ineffective ventilation. Fever or infection can also directly cause tachypnea.

The skin's color, temperature, and condition may indicate underlying thermoregulation abnormalities. Red, flushed faces are common in febrile children. Generalized or central erythema of the face and torso results from vascular dilation. Vasodilation functions as a feedback mechanism that reduces heat retention during fever. Tactile skin temperature examination demonstrates notable accuracy in studies. A patient or caregiver’s report of “hot to touch,” or EMS tactile assessment, should be documented and communicated to receiving medical providers.

Skin findings, including diaphoresis and erythema, may aid in the diagnosis of infectious disease. Diaphoresis and generalized erythema may increase as fever improves because these mechanisms promote heat dissipation. Infectious diseases commonly present with cutaneous rashes. Petechiae or purpura warrant particular concern because of possible vascular or platelet dysfunction or sepsis. Generalized exanthems may also accompany or indicate specific infectious conditions, such as measles or varicella.

Pale or cool extremities resulting from vasoconstriction during hypothermia, particularly without environmental exposure, may suggest infectious disease among other conditions. Decreased capillary refill may reflect dehydration or peripheral vasoconstriction. Peripheral cyanosis may also occur with vasoconstriction, particularly in very young patients. Peripheral vasoconstriction can prolong capillary refill and increase cyanosis while shunting blood from the extremities to critical central organs, including the brain, heart, lungs, and kidneys. Although not specific to fever or infectious disease, chills, shivering, piloerection ("goose bumps"), and altered mental status should increase suspicion for infection.

Blood pressure is a critical component in the assessment of infectious disease. Vascular dilation associated with fever can lower blood pressure and reduce perfusion to essential organs. Risk increases when dehydration or cardiac compromise is present, including medication effects. Hypotension may produce central nervous system dysfunction, decreased urine output, gastrointestinal impairment, and cyanosis. This constellation falls within the spectrum of sepsis and septic shock and represents a critical finding requiring immediate treatment.

In addition to fever, hypothermia is a critical finding in patients with high suspicion for infectious disease. Numerous studies associate hypothermia with increased mortality in sepsis. Assessment of respirations, skin findings, diaphoresis, and blood pressure allows EMS providers to identify both hypothermia and fever, supporting early recognition of sepsis.[9][10][11][12]

Clinical Significance

Safe EMS practice assumes a possible infectious disease when symptoms, history, or physician assessment suggest infection. Prehospital care requires the protection of the patient and EMS personnel and clear communication of the suspected diagnosis to the receiving facility. Thermometers are now frequently available to EMS personnel. Clinical assessment remains a critical component in the diagnosis of infectious diseases.

Evaluation of vital signs, including pulse, respiration, and blood pressure, should accompany a focused physical examination. Tactile skin temperature, color, and condition provide additional clinical information. Altered mental status, decreased cardiac function, and evidence of end-organ failure should increase concern for serious infectious disease or sepsis. Integration of patient history, symptom progression, and exposure history with early recognition of hypothermia or hyperthermia without a thermometer can improve patient outcomes.[13][14]