Sepsis, which is very common in ICUs around the world, increases the mortality, causes deterioration of general condition especially in elderly patients and causes long-term acute care hospitalization and also causing serious harm to the patients and their relatives and the country's economy
7. Different factors that increase mortality can be observed in each ICU and awareness of these causes and timely intervention seri-ously contribute to a reduce in death ratios in the ICU. As an example, if gram-negative bacterias are the most detected agents as a source of sepsis in the ICU, mortality rates may be reduced by empirically initiated antibiotherapy for gram-negative active agents. Apart from individual factors, factors such as high lactate parameter value, use of vasopressors, or prolonged invasive mechanical ventilator support, which have been shown to be effective many times in previous studies, increase mortality
8-10. Villar et al
11 showed that invasive mechanical ventilation is one of the best predictors of mortality in ICU in their study called biological or clinical indicators for estimating ARDS and outcomes in septic cases. In the study of Clar et al
12 in which they investigated the prognostic values in community-acquired sepsis, they observed GCS<13 as a factor that increases in-hospital mortality.
In the study of Peng et al13 it was shown that pro-longed hospital stay in cases with chronic obstructive pulmonary disease increases mortality independently of other risk factors. We evaluated prognostic factors, including lactate, to identify causes of mortality in critically septic patients and similar to the results of these mentioned studies, we found that the combination of low GCS, need for IMV, LOS in ICU and arterial lactate level can predict mortality risk for ICU admission.
Lactate level is used as a global indicator of perfusion and oxygenation adequacy and microcirculatory dysfunction. A rised lactate >2 mmol/L has been associated with increased death rates. According to Surviving Sepsis Campaign Guidelines, in case of lactate levels of >4 mmol/L or systolic blood pressure of less than 90 mmHg, it should be started directly the resuscitation of the cases6. The cause of lactate elevation may be a decrease in clearance from the body, an increase in the amount produced, or it may be possible for every two conditions to occur together. The combination of increased lactate production and decreased lactate clearance can also be observed in severe liver failure, and this condition may become more obvious with hypoperfusion due to multi-organ failure observed in sepsis. Effectively, the clearance of lactate from the body is associated with a decrease in mortality rates. Therefore, the failure to clear serum lactate level turns into a poor prognosis and understanding the cause of lactate elevation is important for increasing treatment success. Lactate levels may rise due to ischemic bowel disease, permanent mitochondrial injury, a severe untreated infection, trauma, multi-organ failure, insufficient cardiac output, damage secondary to a pharmacological agent (for example, caused by metformin), lack of thiamine levels, or other conditions14. Filho et al15 in their study in the ICU, showed that a lactate level of more than 2.5 mmol/L at the time of hospitalization was associated with a significant increase in 28-day mortality. Yao et al16 demonstrated that 24 h lactate clearance rate is independent factor that influence the prognosis of critical care cases. Schork et al17 demonstrated that one of the best indicators of death defined by ROC (Receiver Operating Characteristic) were maximum lactate in 24 hour. Kliegel et al18 in their study of patients who survived at least 48 hours after successful cardiopulmonary resuscitation from cardiac arrest, they deduced that hyperlactatemia worsens the neurological prognosis and is also an important predictor of mortality. Lactate level may vary with laboratory derangements, vasopressor use, steroid use, drug use, trauma, multi-organ failure, infection, excessive muscle activity, burns, smoke inhalation, seizure, regional ischemia, liver dysfunction, diabetic ketoacidosis, and intravenous fluid use. The mentioned parameters could not be evaluated clearly since it is a retrospective study. The number of patients included in the study can be considered insufficient in terms of generalizing the results. The study was carried out retrospectively by scanning the files of the patients in the ICU of a single-center hospital and selection bias cannot be ruled out, making it difficult to generalize the findings to all patients.
In conclusion, our study showed that lactate level was an independent predictor of mortality in septic ICU patients.
Ethical Approval: The study was ratified by the institutional ethic committee of our hospital (date: April 07, 2022; no.60) and informed consent from patients was not provided because of the retrospective investigation.
Conflict of Interest: Authors declared no conflict of interest.
Financial Disclosure: Authors declared no financial support.