Hypoperfusion context as a predictor of 28-d all-cause mortality in septic shock patients:A comparative observational study

BACKGROUND As per the latest Surviving Sepsis Campaign guidelines,fluid resuscitation should be guided by repeated measurements of blood lactate levels until normalization.Nevertheless,raised lactate levels should be interpreted in the clinical context,as there may be other causes of elevated lactate levels.Thus,it may not be the best tool for real-time assessment of the effect of hemodynamic resuscitation,and exploring alternative resuscitation targets should be an essential research priority in sepsis.AIM To compare the 28-d mortality in two clinical patterns of septic shock:hyperlactatemic patients with hypoperfusion context and hyperlactatemic patients without hypoperfusion context.METHODS This prospective comparative observational study carried out on 135 adult patients with septic shock that met Sepsis-3 definitions compared patients with hyperlactatemia in a hypoperfusion context(Group 1,n=95)and patients with hyperlactatemia in a non-hypoperfusion context(Group 2,n=40).Hypoperfusion context was defined by a central venous saturation less than 70%,central venousarterial PCO_(2)gradient[P(cv-a)CO_(2)]≥6 mmHg,and capillary refilling time(CRT)≥4 s.The patients were observed for various macro and micro hemodynamic parameters at regular intervals of 0 h,3 h,and 6 h.All-cause 28-d mortality and all other secondary objective parameters were observed at specified intervals.Nominal categorical data were compared using theχ^(2)or Fisher’s exact test.Nonnormally distributed continuous variables were compared using the Mann-Whitney U test.Receiver operating characteristic curve analysis with the Youden index determined the cutoff values of lactate,CRT,and metabolic perfusion parameters to predict the 28-d all-cause mortality.A P value of<0.05 was considered significant.RESULTS Patient demographics,comorbidities,baseline laboratory,vital parameters,source of infection,baseline lactate levels,and lactate clearance at 3 h and 6 h,Sequential Organ Failure scores,need for invasive mechanical ventilation,days on mechanical ventilation,and renal replacement therapy-free days within 28 d,duration of intensive care unit stay,and hospital stay were comparable between the two groups.The stratification of patients into hypoperfusion and nonhypoperfusion context did not result in a significantly different 28-d mortality(24%vs 15%,respectively;P=0.234).However,the patients within the hypoperfusion context with high P(cva)CO_(2)and CRT(P=0.022)at baseline had significantly higher mortality than Group 2.The norepinephrine dose was higher in Group 1 but did not achieve statistical significance with a P>0.05 at all measured intervals.Group 1 had a higher proportion of patients requiring vasopressin and the mean vasopressor-free days out of the total 28 d were lower in patients with hypoperfusion(18.88±9.04 vs 21.08±8.76;P=0.011).The mean lactate levels and lactate clearance at 3 h and 6 h,CRT,P(cv-a)CO_(2)at 0 h,3 h,and 6 h were found to be associated with 28-d mortality in patients with septic shock,with lactate levels at 6 h having the best predictive value(area under the curve lactate at 6 h:0.845).CONCLUSION Septic shock patients fulfilling the hypoperfusion and non-hypoperfusion context exhibited similar 28-d all-cause hospital mortality,although patients with hypoperfusion displayed a more severe circulatory dysfunction.Lactate levels at 6 h had a better predictive value in predicting 28-d mortality than other parameters.Persistently high P(cv-a)CO_(2)(>6 mmHg)or increased CRT(>4 s)at 3 h and 6 h during early resuscitation can be a valuable additional aid for prognostication of septic shock patients.

Role of cerebrospinal fluid lactate in diagnosing meningitis in critically ill patients

BACKGROUND Meningitis is a life-threatening clinical condition associated with high mortality and morbidity.Early diagnosis and specific treatment may improve outcomes.Lack of specific clinical signs or tests make the diagnosis challenging.AIM To assess the efficacy of cerebrospinal fluid(CSF)lactate in diagnosing meningitis in critically ill patients.METHODS A prospective,observational cohort study was carried out in a neuro-medical intensive care unit(ICU)over a 22 mo period.Adult patients,with suspected meningitis admitted in ICU,were serially recruited.Patients who refused consent,those with peripheral sensorineural deficit,or with any contraindication to lumber puncture were excluded.CSF cytology,bio-chemistry,lactates,culture and polymerase chain reaction based meningo-encephalitis panel were evaluated.Patients were divided in two groups based on clinical diagnosis of meningitis.The efficacy of CSF lactate in diagnosing meningitis was evaluated and compared with other tests.RESULTS Seventy-one patients were included and 23 were diagnosed with meningitis.The mean values of CSF total leucocyte count(TLC),proteins and lactates were significantly higher in meningitis group.There was a significant correlation of CSF lactate levels with CSF cultures and meningo-encephalitis panel.CSF lactate(>2.72 mmol/L)showed good accuracy in diagnosing meningitis with an area under the curve of 0.81(95% confidence interval:0.69-0.93),sensitivity of 82.6%,and specificity 72.9%.These values were comparable to those of CSF TLC and protein.Twelve patients with bacterial meningitis had significantly higher CSF lactate(8.9±4.7 mmol/L)than those with non-bacterial meningitis(4.2±3.8 mmol/L),P=0.006.CONCLUSION CSF lactate may be used to aid in our diagnosis of meningitis in ICU patients.CSF lactate(>2.72 mmol/L)showed good accuracy,sensitivity,and specificity in diagnosing meningitis and may also help to differentiate between bacterial and non-bacterial meningitis.