Resultado de enfermagem equilíbrio hídrico no pós-operatório de cirurgia cardíaca : análise do conceito e construção de definições operacionais

Abstract

This PhD dissertation aimed to review the concept of the nursing outcome Fluid Balance from the Nursing Outcome Classification (NOC) in postoperative patients who underwent cardiac surgery, and develop operational definitions. For so, a concept analysis was carried out according to the Walker and Avant Model (2005), using the integrative review for searching. It was developed from October to December/2010, based on the leading questions: Which indicators allow the body fluid volume assessment on the postoperative period of cardiac surgery? How these indicators are defined and how could they be evaluated? Which features or values are indicative of normal and altered body fluid volume on the postoperative period of cardiac surgery? Water electrolyte balance, thoracic surgery, and postoperative period were used as searching descriptors. The sample consisted of articles which answered at least one of the searching question(s); with full text available through Portal da CAPES, the University of Iowa electronic system, or the interlibrary loan service; in Portuguese, English, or Spanish. Editorials, letters to the editor, qualitative studies, case report studies, proceedings, duplicate articles, and animal research were excluded. The identified works were submitted to a four step evaluation, which resulted on the selection of 48 articles (CINAHL: 12; PubMed: 12; Scopus: 21; Lilacs: 3). Predominated the narrative reviews, cohort, and descriptive studies (level of evidence IV and VI). From the analysis, 14 indicators were identified, plus the 23 present on the Fluid Balance NOC outcome. The integrative review had a limited contribution for the operational definitions construction, mainly due to the nature of the concept of interest. The concept analysis highlighted the attributes: solvent and/or solute movement (active or passive) through semi-permeable membranes and between physiological compartments; effective regulation by homeostatic mechanisms (gradient between hydrostatic and coloidosmotic pressure, electroneutrality, and neurohormonal mechanisms); and maintenance of compartments concentration and volume. The case model represented a healthy individual, with hormonal and fluid compartments control functions preserved, whereas the contrary cases opposed the attributes partially. The borderline cases consisted of morbid situations in which alterations occurred in at most two attributes. The antecedents of fluid balance corresponded to organic, behavioral, and/or environmental conditions that opposed to those listed for the unbalance, or even their absence. The consequences of unbalance encompassed the estates of fluid deficit or excess, as well as the related concepts of hydration, electrolyte balance (sodium) and systemic (volemia) and local (tissue) perfusion. The consequence of balance consisted of the fluid homeostasis or the absence of consequences of unbalance while the empirical referents corresponded to the indicators. The concept analysis allowed its scope delimitation and identify which parameters assure its presence or even its alteration (unbalance). It encompasses the electrolyte balance, perfusion, and hydration phenomena and is beyond the simple measurement and control of fluid intake and output. As initial validity phase of the nursing outcome, it requires the development of experts and clinical research.