To investigate the role of initial venous lactate in predicting the severity progression to overt septic shock and 30-day mortality in non-elderly patients without hemodynamic shock who suspected to have acute infections.

Blood lactate is one of the markers that can predict the organ failures and mortality in emergency department (ED) patients with sepsis. Regarding its predictive role in the clinical deterioration in normotensive sepsis patients, a recent prospective observational study of the patients with moderately-high serum lactate (2.0-3.9 mmol/L) showed that one-forth of the patients eventually developed progressive organ dysfunctions or required vasopressor or mechanical ventilator. Unfortunately, low serum lactate (< 2.5 mmol/L) was still found up to 50% of overt septic shock patients, even in vasopressor-dependent cases. For the prognostic role on mortality, numbers of articles showed that blood lactate can also predict death in sepsis patients, especially in those who are elderly and critically-ill. However, no previous study was done in younger patients since lactate kinetics in the body may differ among the age groups. The primary aim of our study is to investigate the role of initial venous lactate levels in predicting the chance of severity progression to overt septic shock especially in non-elderly patients who suspected to have acute infections and without hemodynamic shock in ED. The secondary outcomes are to evaluate its prognostic role on hospital length of stay and 30-day mortality of this target population.

Inclusion Criteria:

• Age 18 to 65 years
• Confirmed or suspected diagnoses of acute infections (within 7 days)
• Major infections (e.g. Acute pyelonephritis, Acute bronchitis/pneumonia, Acute hepatobiliary tract infections, intrabdominal abscesses, meningitis and other central nervous system infections, soft tissue infections involving more than 10 square centimeters of the skin surface or deeper down beyond the dermis, significant tropical infections; dengue fever, leptospirosis, typhus fevers, or high fever from any infectious sources)
• Systolic blood pressure more than 90 mmHg at presentation
• Mean arterial pressure more than 70 mmHg at presentation

Exclusion Criteria:

• Duplicated cases that have participated in this study during the study period
• Overt organ hypoperfusion (e.g. cold, clammy or mottling skin, altered mental status; Glasgow Coma Scale equal to or less than 12 or decrease > 1 compared with the baseline)
• Pulse oximetry equal to or less than 90% at ambient air
• received intravenous fluid more than 10 ml/kg prior to the venous blood sampling
• received intravenous antibiotics for more than 1 hours prior to the venous blood sampling
• Minor infections (e.g. uncomplicated upper respiratory tract infections, gastroenteritis, minor skin infections)
• currently taking antiretroviral drugs
• having or suspicious of having seizures in the past 72 hours

Emergency department patients of King Chulalongkorn Memorial Hospital (a 1500-bed, tertiary-care, university-affiliated urban hospital)

Overall study period

1. This was an observational study that did not evaluate the aggressiveness of the treatment strategies. 2. The study was done in a single, urban, university hospital. 3. The staging of co-morbidity (e.g. cancers) was not well-categorized.