1. Provide the Legal Record of Care

In order to provide the legal record of care, the system must capture the clinician's expression of patient assessment, diagnosis, goals, the plan of care, the care actually delivered, the patient's responses to care, and the actual patient outcomes. A nomenclature that captures all of the enormous richness of this data set across the spectrum of patient care settings must have what is known as domain completeness. Existing nursing nomenclatures cover various aspects of the nursing process in varying depths in one setting or another, but none can claim domain completeness.

Even if a nomenclature claimed to have terms that describe all of the aspects of care in all settings, it must still support the human tendency to local variation. So the nomenclature must support synonymy, the ability to express the same concept in different ways depending on local preference. At this time, none of our nomenclatures supports synonymy. In addition to representing the entire domain, the terms in the nomenclature must be able to describe care at the clinical level, not at an administrative or epidemiological level; therefore the nomenclature's terms must have sufficient granularity to describe, for example, not only that a wound exists, but what the precise characteristics of the wound are, including size, location, nature and amount of drainage, etc.

Because our patients are complex beings, the description of their conditions is also complex, thus the need for the ability to qualify the description of their conditions with modifiers such "mild," "moderate," and "severe." Because nursing is not a hard science, it must be possible to represent the degree of certainty of a finding (such as "possible xxx" or "probable yyy") and it must also be possible to record a negative finding (such as "no evidence of..." or "patient denies..."). Some of our nomenclatures do have modifiers that can be attached to terms. For example, modifiers such as "potential," "actual," "family," and "individual" can be attached to problem terms in the Omaha System, and NANDA terms can be qualified with such descriptors as "acute," "chronic," "impaired," and so on.

Because human beings operate on their own perceptions of the world, the same term will have different meanings to different people, thus the need for a definition of each term in the nomenclature to insure non-ambiguity. Most of our nomenclatures do contain definitions of their terms, which assists with both understanding the meaning of a particular term, and also helps to assure consistency in use of the term. In fact, definitions for terms is one of the requirements for recognition of a nomenclature by the American Nurses Association, as is demonstrated clinical utility (McCormick, Lang, Zielstorff, Milholland, et al, 1994).

There are other types of attributes that contribute to the description of conditions, actions and patient states that, when combined with core concepts, result in complex phrases such as "Stage 2 pressure ulcer at the right lateral malleolus." A nomenclature that had such a phrase in it would have to have many variants including whether it was stage 1, 2, 3 or 4, the anatomic location, whether it was right or left, lateral or medial, etc. In our example, the entire phrase has been "pre-combined" to include all of the qualifiers. But experience with systems that use pre-combined phrases has shown that as new knowledge and new circumstances arise, the need for new phrases mushrooms; the vocabulary quickly becomes unwieldy, and lacks parsimony.

From an informatics perspective, it would be better if the nomenclature were more "atomic," with all qualifiers supplied from separate "axes" such as laterality (right, left, medial, lateral, etc.), anatomic location, stage or degree, and so on. Such a nomenclature would then be multi-axial and combinatorial, providing not only maximum parsimony, but maximum flexibility and extensibility. A few of our nomenclatures are somewhat combinatorial. The Omaha System, for example, allows combination of problem labels with modifiers, and allows action terms to be combined with "targets" to describe planned actions, but it is not accurate to say at this point that any of them is multi-axial.

When nomenclatures are combinatorial, it is helpful to supply rules for how the different axes can be combined, so that nonsensical phrases such as "left social isolation" do not occur. For example, the Omaha System states that its coded signs and symptoms should not be used when the prefix "Potential" is attached to a problem term. By definition, a problem that is "potential" does not have signs or symptoms. Rules such as this make up the syntax and grammar of a nomenclature.

While a nomenclature that is multi-axial and combinatorial and highly granular is desirable for many reasons, it can also be difficult to use by the clinician. Imagine having to make four clicks to select from four different lists of terms the words that make up the phrase as "Stage 2 pressure ulcer at the right lateral malleolus." One thing that clinicians abhor is an automated system that takes more time to use than the manual system they are used to. The technical challenge in developing a system that is both acceptable to clinicians and also captures data at a granular level in a form that can be manipulated by the computer for several different purposes is enormous. In fact, what we mostly see is compromise: we may ask the clinician to select a core concept from a list of terms (like "Stage 2 Pressure Ulcer") and allow the rest of the detail to be described in narrative text. Of course, it is then not possible to advise the nurse to consider infection when the drainage is described as odorous and purulent if that information is recorded in narrative text rather than in coded terms.

To summarize, a nomenclature that is useful for recording clinical care must have domain completeness, it must support synonymy, it must have sufficient granularity, it must be parsimonious, its terms must be able to be qualified with modifiers (including certainty and negation), and its terms must be non-ambiguous. At the same time, it must be easy to use in the clinical setting.