Biomedical Engineering Reference
In-Depth Information
9.2
Regulatory definition of medical devices
The defi nition of a medical device in the United States (with which there is
fundamental international concurrence) is, according to section 201(h) of
the Food, Drug, and Cosmetic Act, 'as an instrument, apparatus, implement,
machine, contrivance, implant,
in vitro
reagent, or other similar or related
article, including a component, part or accessory, which is:
recognized in the offi cial National Formulary, or the United States
Pharmacopoeia (USP), or any supplement to them,
intended for use in the diagnosis of disease or other conditions, or in
the cure, mitigation, treatment, or prevention of disease, in man or
animals,
intended to affect the structure or any function of the body of man or
other animals, and which does not achieve any of its primary intended
purposes through chemical action within or on the body of man or
other animals and which is dependent upon being metabolized for
the achievement of any of its principal intended purposes' (CDRH,
1992).
In practice, the fi eld of medical diagnostics, which typically relies on
in vitro
evaluation of samples (plasma, serum, blood, urine, feces and others) col-
lected from patients and analyzed externally to the body, is regulated as
devices. Since there is no actual patient contact, there is no correspond-
ing safety concern (arising from the diagnostic device itself) or non-clinical
evaluation of the same. This also applies to imaging devices which operate
externally to the body (X-rays, MRI and CAT scan devices) to the extent
that there is no non-clinical biocompatibility assessment.
9.3
International Standards Organization
(ISO) regulation and guidance
The basic guidance (and regulation) of biocompatibility evaluation arises
not from a governmental body, but rather from ISO, a non-governmental
organization (NGO). The primary defi nition of the non-clinical testing
that is required in the USA to support evaluation of a device in humans
(via the mechanism of an Investigational Device Exemption, or IDE) or
to market approval of a device (via either a 510(k), 513(f) or product mar-
keting approved (PMA)) is to be found in ISO 10993-1:1997, Biological
evaluation of medical devices - Part 1: Evaluation and Testing. This guid-
ance calls for an initial determination of what the nature of patient body
contact will be:
