Serum arterial lactate at the time of admission as a predictor of mortality in patients admitted with severe sepsis and septic shock to an ICU
- Adriell Ramalho Santana1,
- Fábio Ferreira Amorim1,
- Bárbara Magalhães Menezes1,
- Felipe Bozi Soares1,
- Fernanda Vilas Bôas Araújo1,
- Jacqueline Lima de Souza1,
- Mariana Pinheiro Barbosa de Araújo1,
- Louise Cristhine de Carvalho Santos1,
- Pedro Henrique Gomes Rocha1,
- Osvaldo Gonçalves da Silva Neto1,
- Guilherme Menezes de Andrade Filho1,
- Pedro Nery Ferreira Júnior1,
- Alethea Patrícia Pontes Amorim2,
- Rodrigo Santos Biondi3 and
- Rubens Antônio Bento Ribeiro3
© Santana et al.; licensee BioMed Central Ltd. 2013
Published: 5 November 2013
Elevated serum arterial lactate levels are often associated with an imbalance between oxygen demand and delivery, which has a strong correlation with poorer outcomes in critically ill patients [1, 2]. This study aims to evaluate serum arterial lactate as a predictor of mortality in critical patients admitted with severe sepsis and septic shock.
Materials and methods
Retrospective cohort study conducted in the ICU of Hospital Anchieta, Brasília, DF, Brazil, during 3 years. For the first analysis, patients were divided into two groups: group with arterial lactate >2 mmol/l and group with low arterial lactate ≤2 mmol/l at the time of admission. For a second analysis, patients were divided into two groups: group with arterial lactate >3.3 mmol/l and group with arterial lactate ≤3.3 mmol/l at the time of admission.
A total of 195 patients with sepsis were enrolled, 41% (n = 80) with septic shock. Mean age was 63 ± 22 years, ICU length of stay 9 ± 11 days, SAPS3 62 ± 16, and APACHE II 21 ± 9. ICU mortality in 4 days was 10.8% (n = 21), in 28 days was 12.3% (n = 24), and hospital mortality was 26.2% (n = 51). The nonsurvivor patients had higher lactate values (2.0 ± 1.4 vs. 1.3 ± 1.1, P = 0.00). Considering the arterial lactate cutoff value of 2.0 mmol/l, there was no difference between groups regarding ICU length of stay (10 ± 13 vs. 9 ± 2 days, P = 0.47), mortality in 4 days (12% vs. 10%, P = 0.85), mortality in 28 days (13% vs. 16%, P = 0.77), and hospital mortality (30% vs. 32%, P = 0.86). However, considering the lactate cutoff value of 3.3 mmol/l, the high lactate group had higher mortality in 4 days (27% vs. 9%, P = 0.04) and hospital mortality (67% vs. 23%, P = 0.00). There was no statistical significant difference regarding mortality in 28 days (27% vs. 11%, P = 0.08), and ICU length of stay (8 ± 7 vs. 9 ± 11 days, P = 0.59). The relative risk of hospital death in patients with arterial lactate >3.3 mmol/l was 2.93 (95% CI: 1.87 to 4.58). The specificity of arterial lactate >3.3 mmol/l for hospital mortality was 96.5% (95% CI: 92.1 to 98.5%), sensibility was 19.6% (95% CI: 11.0 to 32.5%), and LR+ was 5.65 (95% CI: 2.03 to 15.7%). The arterial lactate area under the ROC curve for mortality was 0.634 (95% CI: 0.540 to 0.748).
In the patients admitted with severe sepsis and septic shock for this sample, the nonsurvivors had higher lactate values. Arterial lactate >2 mmol/l at the time of admission was not associated with mortality. Arterial lactate >3.3 mmol/l was associated with mortality in 4 days, and hospital mortality. Indeed, lactate >3.3 mmol/l had high specificity for hospital mortality.
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