In the previous sections emphasis has been on descriptive concepts and their classification. Interventions, or prescriptive concepts, complete the diagnosis-intervention-outcome linkage that specifies the major elements and relationships that need to be developed for a nursing classification.

Historical Perspective: Intervention Classification

Nurses and administrators have always been interested in identifying what nurses do, perhaps for different reasons. At various points in time, even industrial task analysis was common. Assessing and monitoring medical treatments and technology, administering medications, and assisting the patient to carry out the physicians orders were high priority in the traditional typology of nursing interventions. This situation changed with the publication of nursing theories and philosophies beginning at mid-century and the introduction of nursing diagnosis and clinical judgment. "Independent" nursing interventions that were nurse-initiated were given increased emphasis in curricula and in practice. In the 1980s textbooks began to name nurse-initiated interventions and relate these to nursing diagnoses (Bulechek and McCloskey, 1992; 1985; Maas, Buckwalter, and Hardy, 1991; Snyder, 1985).

Intervention Concept Development

The first systematic approach to naming classes of interventions was reported by McCloskey and Bulechek in 1992 and updated in 1996. The nursing intervention classification (NIC) research team identified a set of intervention concepts through content analysis of the literature and other sources, project team focus groups, and graduate student ratings. Validation procedures included surveys of specialty organizations, individual nurses, nurse experts in theory development (taxonomy and content), and clinical field testing. Currently, over 433 intervention concepts and over 3000 nursing activities have been identified by the research team. Field testing continues in a variety of settings, an important factor when the claim is generalizability to all nursing areas (McCloskey and Bulechek, 1996).

The structure of an intervention includes the concept label, definition, and activities. The close involvement of one of the directors of both the NIC and NOC projects in the NANDA work may have influenced decisions about the structure of interventions and outcomes. All three classification elements consist of a

1. concept label,
2. definition, and
3. referents (defining characteristics, outcome indicators, or activities)

Three types of interventions have been classified by the McCloskey and Bulechek research team in the Iowa project (1992). They are defined as follows:

A nursing intervention is any direct care treatment that a nurse performs on behalf of a client. These treatments include nurse-initiated treatments resulting from nursing diagnoses, physician-initiated treatments resulting from medical diagnoses, and performance of the daily essential functions for the client {who} cannot do these (1992, p.21).

This definition provides clear direction for what is to be classified and, similar to the outcome project, procedures and criteria used in the classification project are clear. Critique of the intervention elements in the NIC includes:

1. various levels of abstraction in the intervention concepts,
2. unnecessary specification of populations or settings that may limit the use of interventions, and
3. the definition of nursing intervention as both autonomous and collaborative (Snyder, Egan, and Nojima, 1996).

Classification of Nursing Interventions

The number of interventions and activities (N=>3000) identified in the Iowa project required the use of a computer clustering. Similarity ratings and hierarchical clustering techniques were used to develop a taxonomy with 34 classes and six domains. The domains are physiological: basic, physiological: complex, behavioral, safety, family, and health system (McCloskey and Bulecheck, 1996, pp. 56-57). The use of nursing's tradifional terms may be necessary when classifications (intervention and outcome) contain both medical and nursing conditions. This is in contrast to the more abstract, but internally consistent, concepts, such as the nine Human Response Patterns (North American Nursing Diagnosis Association, 1996) or the 11 functional health patterns (Gordon, 1994). Perhaps with the start in 1998 of biennial NANDA-NIC-NOC Conferences there will be more contact among developers and a common way of looking at taxonomic structure may emerge.

Multidimensional scaling, factor analysis, and other procedures were used to analyze the dimensional structure of 26 NIC intervention classes. Results suggest that the embedded structure of interventions contains three components: complexity (urgency and skill and knowledge needed), intensity (acuity), and focus of care (target: individual to system) (Tripp-Reimer, Woodworth, McCloskey, and Bulechek, 1996). These are similar in nature to the taxonomic branches proposed for the NANDA classification: acuity, developmental level and individual-family-community.

Similar to a diagnostic and outcome classification, the intervention concepts within the classification represent first level, factor-isolating theory. This is the base for middle range theory development and the structure of nursing science