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Pulmonary lactate production in septic patients with and without ARDS


The lungs may be a source of lactate in septic patients, specially when severe respiratory failure is present. Furthermore, first-days lactate levels have been related to outcome in those patients.


To describe the relationship between pulmonary lactate flux and PaO2/FiO2 ratio in septic patients; to verify the relationship between lactate flux and outcome.


A large general ICU.


Prospective, observational study.


Thirty-two adult septic patients.


All patients were monitored with pulmonary artery catheter and gastric tonometer. Systemic hemodynamic and oxygen variables, arterial and mixed-venous lactate levels, and gastric mucosal pCO2 (PgCO2) were measured every 8 hours for 5 days. PCO2gap (PCO2gap = PgCO2 — PaCO2) and pulmonary lactate flux [(arterial lactate — mixed venous lactate) × cardiac output] were calculated. Results were expressed as median and inter-quartile 25–75%. The median values at the first day were used to statistical analyzes. Mann–Whitney U-test was used to evaluate of differences between the groups.


Mean age was 57 ± 17 years, being higher among patients with ARDS than the ones without ARDS. Mean APACHE II and SOFA scores were 21.5 ± 6.6 and 9.9 ± 2.5, respectively. The lactate flux showed a trend to be greater in non-survivors than survivors septic patients (P = 0.06).


Despite of respiratory failure severity, all septic patients presented pulmonary lactate production, which was significantly greater in patients with ARDS.

Table 1 The first day data for hemodynamic and oxygenation parameters

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Silva, E., Garrido, A., Barbas, C. et al. Pulmonary lactate production in septic patients with and without ARDS. Crit Care 5, P138 (2001).

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  • Lactate
  • Cardiac Output
  • Pulmonary Artery
  • Respiratory Failure
  • Septic Patient