A proper assessment of the vital signs by the nurse will allow them to do three things: evaluate improvement of the patient’s condition, implement planned interventions, and identify a nursing diagnosis. For example, if the vital signs are showing an elevated blood pressure, which was not there a few hours ago, then the nursing diagnosis and the planned interventions will change.
However, a proper assessment will also keep the patient and the hospital safe. If a nurse misreads something, and it can be proven, then the hospital is liable for that injury. But if a patient has tampered with the machines (rare, but possible), a nurse trained to keep careful notes of what reactions have happened would know that it wasn’t natural.