Material and Method: Hundred and ten septic patients who were followed up in ICU between March 2021 and November 2021 were included in this study. The patients included in the study were divided into two groups as survivors and deceased and all the parameters studied were statistically analyzed for both groups.

Results: Sixty-six (60%) were male of 110 patients. The mean age was 62(49-72) years. Mortality rate was 58%. LOS (length of stay) in ICU was 4(2-6) days. Septic shock was diagnosed in 60 (54.5%) of the patients upon admission to the ICU. The requirements for IMV (invasive mechanical ventilation) and NIMV non- invasive mechanical ventilation) for patients were 70(63.6%) and 43(39.1%), respectively. APACHE-II score was 24±9. Mean arterial lactate level was 3.5(2.4-5.2). As a result of the logistic regression analysis, Glasgow coma scale (GCS), requirement for IMV, arterial lactate level and LOS in ICU were determined as independent risk variables for mortality (OR =1.304 (1.073-1.586), p =0.008, OR =5.747 (1.501-22.002), p =0.011, OR =1.703 (1.190-2.518), p =0.004, OR =1.472 (1.042-2.213), p =0.04), respectively.

Conclusion: As a result of the logistic regression analysis, GCS, requirement for IMV, arterial lactate level and LOS in ICU were determined as independent risk variables for mortality.

Statistical analysis
Kolmogorov-Smirnov test was used to investigate the conformity of the data to the normal distribution and continuous data were given as mean ± standard deviation or median and interquartile range. In the compari-son of measurement data, independent samples t-test was used in independent groups and Mann-Whitney-U test was used in cases where normal distribution could not be achieved. Pearson Chi-Square and Fisher's exact tests analyzes were used in the analysis of the created cross tables. Binary logistic regression was applied to determine association between mortality and covariates. Patients were divided into two groups as the survivors and nonsurvivors and the differences between the two groups were analyzed for all variables. The outcomes of the regression analyses were expressed as odds ratio (OR) and 95% confidence interval (CI). A p-value less than 0.05 were presumed statistically significant. Statistical analyses were carried out using IBM SPSS version 22.0.

Power analysis
The group of patients included in this study provided 0.98 actual power and 0.72 effect size according to conventional acceptable values that for power and α are 80% or above and 5% or below, respectively. In summary, this study has sufficient power and level of effect size. The power level and effect size calculated in this study were determined using the G* Power Version 3.1.9.4.

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Table 1: Baseline characteristics of the patients.

In the binary logistic regression analysis, GCS, need for IMV, arterial lactate and LOS in ICU were found to be independent risk factors for mortality (OR =1.304 (1.073-1.586), p =0.008, OR =5.747 (1.501-22.002), p =0.011, OR =1.703 (1.190-2.518), p =0.004, OR =1.472 (1.042-2.213), p =0.04), respectively (Detailed demographic characteristics were described in table 2).

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Table 2: Multivariable binary logistic regression modeling of parameters for 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.

1) Singer M, Deutschman CS, Seymour CW et al. The Third International Consensus Definitions for Sepsis and Septic Shock (Sepsis-3). JAMA 2016; 315: 801-10.

2) Khosravani H, Shahpori R, Stelfox HT, Kirkpat-rick AW, Laupland KB. Occurrence and adverse effect on outcome of hyperlactatemia in the critically ill. Crit Care 2009; 13: 90.

3) Sheikh T, Shuja H, Bin Waqar SH. Frequency of Hyperlactatemia in Intensive Care Patients within Tertiary Care Hospital in Pakistan. Cureus 2020; 12: e8264.

4) Garcia-Alvarez M, Marik P, Bellomo R. Sepsis-associated hyperlactatemia. Crit Care 2014; 18: 503.

5) Casserly B, Phillips GS, Schorr C et al. Lactate measurements in sepsis-induced tissue hypoperfusion: results from the Surviving Sepsis Campaign database. Crit Care Med 2015; 43: 567-73.

6) Evans L, Rhodes A, Alhazzani W et al. Surviving Sepsis Campaign: International Guidelines for Management of Sepsis and Septic Shock 2021. Crit Care Med 2021; 49: e1063-143.

7) Vincent JL, Rello J, Marshall J et al. International study of the prevalence and outcomes ofinfection in intensive care units. JAMA 2009; 302: 2323-9.

8) Sauer CM, Gómez J, Botella MR et al. Understanding critically ill sepsis patients with normal serum lactate levels: results from U.S. and European ICU cohorts. Sci Rep 2021; 11: 20076.

9) López R, Pérez-Araos R, Baus F et al. Outcomes of Sepsis and Septic Shock in Cancer Patients: Focus on Lactate. Front Med (Lausanne) 2021; 8: 603275.

10) Bou Chebl R, Tamim H, Abou Dagher G et al. Sepsis in endstage renal disease patients: are they at an increased risk of mortality? Ann Med 2021; 53: 1737-43.

11) Villar J, Herrán-Monge R, González-Higueras E et al. Clinical and biological markers for predicting ARDS and outcome in septic patients. Sci Rep 2021; 11: 22702.

12) Clar J, Oltra MR, Benavent R et al. Prognostic value of diagnostic scales in community-acquired sepsis mortality at an emergency service. Progno-sis in community-adquired sepsis. BMC Emerg Med 2021; 21: 161.

13) Peng LG, Zhou C, Zhou HX et al. Risk factors associated with in-hospital mortality in hospitalized patients with acute exacerbation of chronic obstructive pulmonary disease: a multicenter retrospective study. Zhonghua Yi Xue Za Zhi 2021; 101: 3932-7.

14) Andersen LW, Mackenhauer J, Roberts JC, Berg KM, Cocchi MN, Donnino MW. Etiology and therapeutic approach to elevated lactate levels. Mayo Clin Proc 2013; 88: 1127-40.

15) Filho RR, Rocha LL, Corrêa T, Pessoa CM, Co-lombo G, Assuncao MS. Blood lactate levels cu-toff and mortality prediction in sepsis-time for a reappraisal? A retrospective cohort study. Shock 2016; 46: 480-5.

16) Yao L, Zhang L, Zhou C. Analysis of Prognostic Risk Factors of Sepsis Patients in Intensive Care Unit Based on Data Analysis. J Healthc Eng 2022; 2022: 3746640.

17) Schork A, Moll K, Haap M, Riessen R, Wagner R. Course of lactate, pH and base excess for prediction of mortality in medical intensive care patients. PLoS One 2021; 16: e0261564.

18) Kliegel A, Losert H, Sterz F et al. Serial lactate determinations for prediction of outcome after cardiac arrest. Medicine 2004; 83: 274-9.