title: Fluid and electrolyte balance after major thoracic surgery by bioimpedance and endocrine evaluation.
abstract: OBJECTIVE
  Weight gain with oedema development is a complication of major surgical procedures with an incidence as high as 40%. Fluid retention is not always clinically evident and it is reported despite fluid-restriction regime. The causes are several and not totally clear. We performed a prospective study to assess the amount of fluid accumulation and redistribution observed after major thoracic surgery.
  
  
  METHODS
  In 49 patients submitted to lobectomy with systematic lymph node dissection for lung cancer, we measured preoperatively and on the postoperative days 1, 2, 4 and 7, body weight, fluid balance, brain natriuretic peptide (BNP) and bioimpedance analysis (BIA)-derived parameters resistance (R) and reactance (X(c)).
  
  
  RESULTS
  The postoperative course was characterised by significant changes. Mean increase in body weight was 2.7 kg ((1.9-3.4); p<0.001) on postoperative day 2. Most of the patients had a negative basal fluid balance (-244 ml (-520 to -50)), whereas, on postoperative day 2, we observed a positive and significant change (+968 ml (646-1456), p<0.001)). Total body R and X(c) fell on the first day (p<0.001), anticipating the changes in weight and fluid balance. BNP increased on day 1, immediately after surgery, and remained significantly above basal values for the entire observation period (p<0.001), in the absence of clinical signs of heart failure.
  
  
  CONCLUSIONS
  The three methods used consistently showed a significant fluid retention over the course of the study. BIA was an easy, reproducible and non-invasive method for the estimation and early detection of fluid retention. Increase in BNP may be related to the systemic reaction to stress and to the decreased pulmonary vascular bed. We found no correlation between fluid retention and length of anaesthesia, sex, age, blood loss and body mass index. The clinical and prognostic implication of weight gain may be relevant to patient's health.
authors.affiliation: Thoracic Surgery Unit, Ospedale S.Maria della Misericordia, University of Perugia, Perugia, Italy. lucio.cagini@unipg.it
authors.forename: Lucio
authors.initials: L
authors.lastname: Cagini
authors.forename: Rosanna
authors.initials: R
authors.lastname: Capozzi
authors.forename: Valentina
authors.initials: V
authors.lastname: Tassi
authors.forename: Claudia
authors.initials: C
authors.lastname: Savignani
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Quintaliani
authors.forename: Gianpaolo
authors.initials: G
authors.lastname: Reboldi
authors.forename: Francesco
authors.initials: F
authors.lastname: Puma
mesh_terms: D000368:Aged; D015415:Biomarkers / Q000097:blood; D004487:Edema / Q000175:diagnosis / Q000209:etiology; D017097:Electric Impedance; D004568:Electrodiagnosis / Q000379:methods; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000601:surgery*; D008197:Lymph Node Excision; D008297:Male; D008875:Middle Aged; D020097:Natriuretic Peptide, Brain / Q000097:blood; D011013:Pneumonectomy / Q000009:adverse effects*; D011446:Prospective Studies; D014883:Water-Electrolyte Imbalance / Q000175:diagnosis / Q000209:etiology*; D015430:Weight Gain / Q000502:physiology
chemical_list: D015415:Biomarkers; D020097:Natriuretic Peptide, Brain