In medicine, clinical engineering can be considered a subset of biomedical engineering, which deals with devices and techniques, often life-critical, which attach directly to patients or are in the immediate patient environment. For example, an artificial pacemaker is clearly part of this field, an electrocardiograph or especially cardiac monitor is generally accepted as one, but a database of heart rhythms would be general biomedical engineering or clinical informatics.
In few places is the Hippocratic principle of "do no harm" as relevant, especially with monitoring and measuring equipment that should be passive but could carry an electrical impulse into the patient. Once the skin resistance is broken, far smaller currents are needed to induce lethal arrythmias. Any monitoring lead that enters the patient, therefore, must not be an antenna; the environment in which it operates may also need protections such as prohibition of cellular telephones or safety prequalification of any wireless devices.