Automated devices measure physiological data, known as vital signs, including body temperature, pulse rate, blood pressure, and oxygen saturation. Using a machine provides a consistent and efficient method for tracking trends and identifying changes in a person’s overall health status. Accurate monitoring requires careful preparation of both the patient and the equipment.
Preparing the Patient and Monitoring Equipment
Accurate vital sign collection begins with ensuring the person is in a state of rest, which significantly influences the resulting numbers. Before any measurement, the individual should be seated quietly for at least five minutes, especially prior to taking blood pressure. Movement, talking, or recent physical exertion can artificially inflate heart rate and blood pressure readings, leading to inaccurate results.
Proper body positioning is necessary for obtaining reliable blood pressure readings. The patient should sit upright with their back supported and their feet flat on the floor, not crossed, which can alter blood flow dynamics. The arm selected for the measurement must be supported at the level of the heart; letting the arm hang down can cause the reading to register falsely high.
Equipment readiness is equally important. Technicians should confirm the monitor is charged and that all sensors and probes are clean and free of debris. Using the correct size attachments, such as a properly sized blood pressure cuff, is paramount because an incorrect size can lead to a significant miscalculation of the pressure. A quiet space and comfortable temperature also help ensure the person remains relaxed.
Operating the Monitor: Taking Core Vitals
Automated Blood Pressure (BP)
Automated blood pressure measurement relies on the oscillometric method, which detects the vibrations of the arterial wall as the cuff deflates. The correct cuff must be selected based on the upper arm circumference, ensuring the bladder wraps around at least 80% of the arm. The cuff should be placed snugly on the bare upper arm, resting approximately one inch above the elbow crease.
Many cuffs feature an artery marker that must be aligned over the brachial artery. Once secured, the measurement is initiated by pressing the start button. The device automatically inflates the cuff to temporarily stop blood flow, then slowly releases the pressure while recording the systolic and diastolic pressure values.
Pulse and Oxygen Saturation (SpO2)
Pulse and oxygen saturation are commonly measured simultaneously using a pulse oximeter, a non-invasive device that clips onto a finger, toe, or earlobe. It uses light-emitting diodes to shine light through the tissue and a photodetector to measure absorption. Because oxygenated and deoxygenated hemoglobin absorb light differently, the device calculates the percentage of oxygen saturation (SpO2).
The sensor should be placed on a clean finger, free of dark nail polish or artificial nails, which can interfere with light transmission. The person must hold the finger still until the device displays a stable waveform, indicating a reliable signal. The monitor displays the SpO2 percentage along with the pulse rate in beats per minute.
Temperature (Temp)
Electronic thermometers provide rapid measurement of body temperature using specialized probes for different body sites.
Measurement Methods
- For temporal artery scanning, the device is gently swiped across the forehead, measuring the infrared heat emitted from the temporal artery.
- For a tympanic (ear) measurement, a clean probe cover is applied, and the probe tip is gently inserted into the ear canal to detect infrared energy from the eardrum, which closely reflects the body’s core temperature.
- When measuring oral temperature, a probe cover should also be used, and the sensor placed under the tongue, ensuring the mouth remains closed until the reading is complete.
While most modern vital signs monitors automate the collection of these three measurements, they generally do not provide an accurate, automated measure of respiratory rate. Respiratory rate, the number of breaths per minute, often still requires a manual observation and count by the person taking the vitals, as electronic methods can be unreliable.
Understanding and Responding to the Readings
Interpreting the numerical results is the final step in the monitoring process, providing the context necessary for deciding on a course of action. For a healthy adult, a normal blood pressure reading is generally considered to be less than 120/80 mmHg, while a resting pulse rate typically falls between 60 and 100 beats per minute. Body temperature usually averages around 98.6°F (37.0°C), with oxygen saturation expected to be 95% or higher on room air.
Certain readings qualify as “red flags” and suggest a potentially serious deviation from a healthy baseline, requiring prompt attention. A systolic blood pressure reading below 90 mmHg or a pulse rate that is extremely low, such as under 50 beats per minute, or very high, exceeding 120 beats per minute, warrants immediate concern. Similarly, an oxygen saturation reading that drops below 90% indicates significant hypoxemia, and a temperature above 101°F (38.3°C) signals a fever that may require intervention.
Following any measurement, it is important to accurately document the time, date, and specific reading for all the vital signs collected. If a single reading falls outside the normal range but is not in the “red flag” category, the safest initial step is often to ensure correct technique and repeat the measurement after a few minutes of quiet rest. However, if the reading is in the critical range, if the person is showing visible signs of distress, or if repeated measurements continue to show abnormal results, then contact with a healthcare professional should be made without delay.