Beyond the Basics: Interpreting Vital Signs

Following is a discussion of some of the normal and abnormal findings that may assist you in more accurately interpreting vital sign data obtained from patients.


CEU Review Form Interpreting Vital Signs (PDF)Valid until Febuary 6, 2007

Assessing vital signs is a standard component of any patient assessment. The five vital signs to be obtained are respiration, pulse, skin, blood pressure and pupils. Some literature suggests considering pulse oximetry as the sixth vital sign. Baseline refers to the first set obtained on that patient. It is extremely important to cognitively process the baseline values, since trends in the patient's condition, such as improvement, stability or deterioration, are identified using this data.

     Some vital sign findings may present as abnormal and indicate a significant patient pathology, whereas, other findings that appear to be abnormal are indeed a normal response. Following is a discussion of some of these normal and abnormal findings that may assist you in more accurately interpreting vital sign data obtained from patients.

Respiration
     When assessing respiration, it is important to determine not only respiratory rate, but also tidal volume. Respiratory rate alone does not provide an indication of the adequacy of respiratory status. In order for a patient to be breathing adequately, he must have a respiratory rate that is adequate and an adequate tidal volume. Thus, it is two "adequates" (rate and tidal volume) that constitute adequate breathing. Only one "inadequate" establishes an inadequate ventilatory status and requires immediate intervention with positive pressure ventilation.

     Respiratory rate is determined by counting the number of respirations (one inhalation and one exhalation = one respiration) in one minute. On average, adult patients breathe between 12 and 20 times per minute. A respiratory rate outside of that average range may be considered abnormal. However, recognize that a patient can have a resting respiratory rate of less than 12 or greater than 20 and not be considered to have an abnormal respiratory rate. As an example, if a patient has a resting respiratory rate of 10 per minute and displays no evidence of respiratory distress or hypoxia; he is talking clearly and normally; and he is alert and oriented to person, place and time, a respiratory rate of 10/minute in this patient would clearly not be considered abnormal.

     On the other hand, elderly patients typically have higher resting respiratory rates due to decreases in tidal volumes. It would not necessarily be abnormal for an elderly patient to have a resting respiratory rate of 20-22/minute. Once again, consider the respiratory rate in conjunction with other physical findings to make a clinical judgment of normalcy.

     Tachypnea (faster than normal respiratory rate) usually indicates cellular hypoxia, acidosis or conditions that interfere with gas exchange, ventilation or perfusion, such as pulmonary edema, pneumonia and pulmonary embolism. As perfusion of cells with oxygenated blood begins to decrease, cells may be forced to convert from aerobic metabolism (metabolism of glucose with oxygen), where the byproduct of carbon dioxide and water is produced, to anaerobic metabolism (glucose metabolism without oxygen), where lactic acid is a primary byproduct. As the metabolic acid level increases within the body, the respiratory rate will increase in an attempt to reduce the acid load. Thus, you can expect tachypnea as an early sign in the shock patient with poor tissue perfusion.

     A patient who presents with tachypnea and exhibits no signs of distress, and has no evidence of any trauma that would explain the etiology of the tachypnea or any other overt clinical reason for the fast respiratory rate, would be described as having "quiet tachypnea." Quiet tachypnea is often a sign of metabolic acidosis.

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