Vital Signs and Clinical Measurement
This domain tests measurement technique and the judgment to know when a number is artifact and when it is a finding to escalate. NCT items often pair an abnormal value with a technique error and ask you to sort out which one you are looking at.
Core ranges for adults
Heart rate 60–100 beats/min; respiratory rate 12–20 breaths/min; blood pressure under 120/80 mmHg is normal, and a systolic of 90 or below or a drop of 20 mmHg (10 mmHg diastolic) within three minutes of standing indicates orthostatic hypotension; oral temperature roughly 36.5–37.5 °C (97.7–99.5 °F); oxygen saturation 95% or higher on room air.
Technique that changes the reading
- Count respirations for a full 60 seconds when irregular, otherwise 30 seconds and double; a radial pulse counted for 15 seconds and multiplied is only acceptable when the rhythm is regular.
- Use an apical rate for 60 seconds when the radial pulse is irregular or a deficit is suspected.
- Cuff too small gives a falsely high blood pressure; arm below heart level also reads high. Seat the patient quietly for five minutes, support the arm at heart level, and wait at least 30 seconds before repeating.
- Pulse oximetry is unreliable with cold fingers, poor perfusion, dark nail polish, or motion; never place the probe on the arm wearing the blood pressure cuff.
Worked example. You record 152/94 on an obese patient using the standard adult cuff, which barely closes. What is the correct interpretation and next step? The reading is likely falsely elevated because the bladder is too small for the arm circumference. Obtain a large adult or thigh cuff, recheck with the arm supported at heart level, and report the corrected value rather than charting the first number.
Traps: reporting a single abnormal value without rechecking technique; counting an irregular pulse for 15 seconds; charting a saturation taken from a cold, blue fingertip; treating pain as something other than a vital sign that must be assessed and reported.