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The effect of excess fluid balance on the mortality rate of surgical patients: a multicenter prospective study

João M Silva124*, Amanda Maria Ribas Rosa de Oliveira23, Fernando Augusto Mendes Nogueira1, Pedro Monferrari Monteiro Vianna1, Marcos Cruz Pereira Filho1, Leandro Ferreira Dias1, Vivian Paz Leão Maia1, Cesar de Souza Neucamp1, Cristina Prata Amendola3, Maria José Carvalho Carmona2 and Luiz M Sá Malbouisson2

Author Affiliations

1 Hospital do Servidor Público Estadual-SP, R. Pedro de Toledo, 1800, Vila Clementino, São Paulo, SP 04039-004, Brazil

2 Hospital das Clinicas SP-FMUSP, Anesthesiology Department, Av. Dr. Enéas de Carvalho Aguiar, 255, Cerqueira César, São Paulo, SP 05403-000, Brazil

3 Hospital do Câncer de Barretos, Rua Antenor Duarte Vilela, 1331 - Doutor Paulo Prata, Barretos, SP 14780-000, Brazil

4 Faculdade de Medicina da Universidade de São Paulo (FMUSP), Anesthesiology Postgraduate, Av. Dr. Arnaldo, 455, Cerqueira Cesar, São Paulo, SP 01246-903, Brazil

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Critical Care 2013, 17:R288  doi:10.1186/cc13151

Published: 10 December 2013



In some studies including small populations of patients undergoing specific surgery, an intraoperative liberal infusion of fluids was associated with increasing morbidity when compared to restrictive strategies. Therefore, to evaluate the role of excessive fluid infusion in a general population with high-risk surgery is very important. The aim of this study was to evaluate the impact of intraoperative fluid balance on the postoperative organ dysfunction, infection and mortality rate.


We conducted a prospective cohort study during one year in four ICUs from three tertiary hospitals, which included patients aged 18 years or more who required postoperative ICU after undergoing major surgery. Patients who underwent palliative surgery and whose fluid balance could change in outcome were excluded. The calculation of fluid balance was based on preoperative fasting, insensible losses from surgeries and urine output minus fluid replacement intraoperatively.


The study included 479 patients. Mean age was 61.2 ± 17.0 years and 8.8% of patients died at the hospital during the study. The median duration of surgery was 4.0 (3.2 to 5.5) h and the value of the Simplified Acute Physiology Score (SAPS) 3 score was 41.8 ± 14.5. Comparing survivors and non-survivors, the intraoperative fluid balance from non-survivors was higher (1,950 (1,400 to 3,400) mL vs. 1,400 (1,000 to 1,600) mL, P <0.001). Patients with fluid balance above 2,000 mL intraoperatively had a longer ICU stay (4.0 (3.0 to 8.0) vs. 3.0 (2.0 to 6.0), P <0.001) and higher incidence of infectious (41.9% vs. 25.9%, P = 0.001), neurological (46.2% vs. 13.2%, P <0.001), cardiovascular (63.2% vs. 39.6%, P <0.001) and respiratory complications (34.3% vs. 11.6%, P <0.001). In multivariate analysis, the fluid balance was an independent factor for death (OR per 100 mL = 1.024; P = 0.006; 95% CI 1.007 to 1.041).


Patients with excessive intraoperative fluid balance have more ICU complications and higher hospital mortality.