A truly noninvasive medical measurement is any measurement system that does not
physically breach the skin or enter the body deeply through an external orifice. Thus,
the measurement of body temperature with a thermometer in the mouth, rectum, or
ear canal is considered noninvasive, as is the use of an otoscope to examine the
outer surface of the eardrum. Similarly, the opthalmoscope and the slit lamp, which
shine light in the eyes to examine the retina and the cornea and lens, respectively,
are considered noninvasive procedures....
According to ASTM Standard Guide nondestructive term
Test, the sound emission is usually defined as the class of phenomena
whereby transient elastic waves generated by the rapid release of energy from
source localization in the material. Energy consumption is essentially due to phase
converter, crack formation and development, friction or movement of dislocations. Acoustic
emission signal can be generated by phenomena such as cavitation, leakage,
solidification and liquefaction.
Unstable Angina and Myocardial Infarction
(See also Chaps. 238 and 239) Patients with these acute ischemic syndromes usually complain of symptoms similar in quality to angina pectoris, but more prolonged and severe. The onset of these syndromes may occur with the patient at rest, or awakened from sleep, and sublingual nitroglycerin may lead to transient or no relief. Accompanying symptoms may include diaphoresis, dyspnea, nausea, and light-headedness.
The physical examination may be completely normal in patients with chest discomfort due to ischemic heart disease.