To Determine Blood Lactate Levels in Patients with Sepsis Admitted to a Respiratory Intensive Care Unit and to Correlate with their Hospital Outcomes

Sepsis is one of major causes of mortality in non-cardiac ICU patients. The screening of the patients for sepsis needs a careful evaluation of criteria and confirmation of infection. SIRS criteria for identification of patients with sepsis is not alone sufficient. Lactate has been shown to be a very important severity marker in sepsis cases and has been found to be more useful for predicting the outcome of sepsis than common severity scores such as the Age and Chronic Health Evaluation (APACHE) II score and the Sepsis related Organ Failure Assessment (SOFA) score. The levels of lactate are very high in sepsis patients and earlier studies have tried to correlate the lactate levels with the onset and mortality associated with sepsis. Though evidence exists that lactate can be used as diagnostic marker in critically ill patients all the studies have been done only in Western countries. The present study aims at correlation between lactate levels and sepsis in Indian patients. Our study found significantly higher mean lactate values among patients of sepsis than control group (3.13 ± 2.86 vs. 2.16 ± 1.86 respectively, p = 0.03). The proportion of subjects with high lactate clearance (> 10% clearance) were higher among survivors as compared to non-survivors, while those with low lactate clearance (< 10% clearance) were higher among non-survivors than survivors within 6 hours, and between 12 to 18 hours of admission. Survival analysis between subjects with high and low lactate clearance within 6 hours and between 12 to 18 hours of admission showed a significantly higher survival in the group with high lactate clearance. Thus, this study is one of the earliest ones which shows that lactate levels and clearance could be used as reliable marker for non-cardiac ICU patients with infection and sepsis onset in Indian scenario. ISSN: 2474-3674 DOI: 10.23937/2474-3674/1510045 Asati et al. Int J Crit Care Emerg Med 2018, 4:045 • Page 2 of 14 • derlying each of the organ failures also need to consider while addressing the sepsis. So, based on these criteria newer definitions of sepsis have been developed. Sepsis is defined as life-threatening organ dysfunction caused by a dysregulated host response to infection. Sepsis is a syndrome which is caused by activity of both infective pathogen and the host immune system. Organ dysfunction is usually assessed on basis of sepsis related organ failure assessment (SOFA) score. A higher SOFA score is associated with mortality. The SOFA score is a six-organ dysfunction/failure score, which is graded from 0 (Normal) to 4 (the most abnormal) providing a maximum of 24 points. qSOFA criteria for assessment of sepsis include three major considerations which are Respiratory rate ≥ 22/min, Altered mentation and Systolic blood pressure ≤ 100 mmHg [18-20]. Sepsis and Systemic Inflammatory Response Syndrome (SIRS) Systemic inflammatory response syndrome or SIRS is nonspecific and can be caused by ischemia, inflammation, trauma, infection or any other insult to the body. SIRS is not always related to infection. SIRS is defined and identified based on atleast two of the four parameters identified by American College of Chest Physicians (ACCP) and Society of Critical Care Medicine’s (SCCM) respectively. The four parameters include: Heart rate > 90 beats per minute (tachycardia), Body temperature < 36 °C (96.8 °F) or > 38 °C (100.4 °F) (hypothermia or fever), Respiratory rate > 20 breaths per minute or, on blood gas, a PaCO2 less than 32 mmHg (4.3 kPa) (tachypnea or hypocapnia due to hyperventilation) and White blood cell count < 4000 cells/mm3 or > 12000 cells/mm3 (< 4 × 109 or > 12 × 109 cells/L), or greater than 10% band forms (immature white blood cells). If any of the two are met, then it is defining as SIRS. SIRS do not lead to sepsis. Sepsis is systemic response to infection. Patients with sepsis have SIRS along with infection which complicates the whole condition. Patients with severe sepsis have SIRS, infection and additional organ dysfunction symptoms with hypoperfusion and hypertension usually seen. The distinction between SIRS and sepsis is important though both are usually used in conjunction with one another [5]. Diagnostic factors for sepsis Diagnostic features for sepsis and severe sepsis and septic shock are indicated below. A. General variables (include the routine parameters for assessment) 1. Fever (core temperature, > 38.3 °C). 2. Hypothermia (core temperature, < 36 °C). 3. Elevated heart rate (> 90 beats per min or > 2 SD above the upper limit of the normal range for age). 4. Tachypnea. organ failure [8]. Therapeutic interventions to deal with increased blood lactate levels have been going on for long time. Studies done in patients for correcting lactate levels have shown that the controlling lactate alone does not help to improve the outcome in critically ill patients [9,10]. A combination therapy of improving oxygen supply, decreasing lactate would be far more useful in controlling morbidity and mortality [11-14]. Breakthrough studies done on human lactate levels showed that an increase in lactate levels from 2.1 to 8 mmol/L decreased the survival from 90% to 10% [15]. Studies on hemodynamically stable surgical patients found significantly higher levels of lactate at 12, 24, and 48 hours after surgery in non-survivors. Several other studies also have shown that high levels of lactate despite therapy can cause significant drop in survival. Studies from Nguyen HB, et al. [16] showed that a lactate clearance cutoff of < 10% had the maximum sum of sensitivity plus specificity for predicting in-hospital mortality. The lactate clearance was calculated based on lactate at Emergency Department (ED) presentation at hour 0 minus lactate at hour 6, divided by lactate at ED presentation, then multiplied by 100. The subjects were categorized as being in the low-clearance group which was less than 10% lactate clearance or high-clearance group which is > 10% lactate clearance. After 6 hrs of intervention, a lactate clearance of < 10% had a sensitivity of 44.7%, specificity of 84.4%, and accuracy of 67.6% for predicting in-hospital mortality [16]. A multicenter prospective study by Arnold RC, et al. [17] in 166 subjects with severe sepsis showed, lactate non-clearance was found to be an independent predictor of death (odds ratio, 4.9 [confidence interval, 1.5-15.9]). The study concluded that failing to clear lactate during resuscitation carried a high risk of death [17].