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Postoperative MeningitisPostoperative MeningitisDiagnosing using CSF LactateDiagnosing using CSF Lactate
Shashwat MishraShashwat Mishra, Deepak Agrawal, BS Sharma, Deepak Agrawal, BS Sharma
Dept of Neurosurgery,Dept of Neurosurgery,
All India Institute of Medical SciencesAll India Institute of Medical Sciences
New Delhi-110029New Delhi-110029
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INTRODUCTION INTRODUCTION
POSTOPERATIVE MENINGITISPOSTOPERATIVE MENINGITIS A neurosurgical diagnostic dilemmaA neurosurgical diagnostic dilemma Symptoms and signs not dependableSymptoms and signs not dependable CSF pleocytosis due to operative insultCSF pleocytosis due to operative insult Blood and blood degradation products further Blood and blood degradation products further
confuse the diagnosisconfuse the diagnosis
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Diagnose early and reliably!Diagnose early and reliably!
Need for early diagnosisNeed for early diagnosis Medical emergencyMedical emergency
Need for confident diagnosisNeed for confident diagnosis Indiscriminate antimicrobial therapy promotes Indiscriminate antimicrobial therapy promotes
antibiotic resistanceantibiotic resistance
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Recommended criteriaRecommended criteria
Culture positive, which is the gold standard, Culture positive, which is the gold standard, along with PMN count >250/cummalong with PMN count >250/cumm
PMN count>500/cumm (when culture is PMN count>500/cumm (when culture is negative and patient received antibiotics and negative and patient received antibiotics and steroids)steroids)
Leib et al : Clinical and infectious diseases 1999:29 :69-74Leib et al : Clinical and infectious diseases 1999:29 :69-74
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Actual ScenarioActual Scenario
CSF hemorrhagicCSF hemorrhagic Cultures rarely positiveCultures rarely positive CSF Sugar may be spuriously lowCSF Sugar may be spuriously low
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Aims and objectivesAims and objectives
To determine biochemical markers which may To determine biochemical markers which may have increased sensitivity in detecting have increased sensitivity in detecting postoperative meningitispostoperative meningitis
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Materials & MethodsMaterials & Methods
Prospective study over three month periodProspective study over three month period
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Materials and methodsMaterials and methods
Test groupTest group Operated NS patients with fever and clinical Operated NS patients with fever and clinical
suspicion of meningitissuspicion of meningitis
Control groupControl group Patients who had lumbar drain/EVD placed Patients who had lumbar drain/EVD placed
prophylactically for CSF , no clinical suspicion prophylactically for CSF , no clinical suspicion of meningitisof meningitis
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Materials & MethodsMaterials & Methods
Parameters assessedParameters assessed CSF cell count (WBC/RBC)CSF cell count (WBC/RBC) CSF Sugar & ProteinCSF Sugar & Protein CSF Lactate (Using ABG machine*)CSF Lactate (Using ABG machine*) CSF CultureCSF Culture
* * Validated from a standard labValidated from a standard lab
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CSF Sampling frequencyCSF Sampling frequency
Test groupTest group Day 1, 3 and 7Day 1, 3 and 7
Control groupControl group Day 1, 3 and 5 ,+/- 7Day 1, 3 and 5 ,+/- 7
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Materials & MethodsMaterials & Methods
Corrected CSF WBC countCorrected CSF WBC count
(WBC – (RBC /600))(WBC – (RBC /600))
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Materials & MethodsMaterials & Methods
AIIMS protocolAIIMS protocol All patients with suspected meningitis are started All patients with suspected meningitis are started
on 3on 3rdrd gen Cephalosporin + Aminoglycoside gen Cephalosporin + Aminoglycoside empiricallyempirically
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Materials & MethodsMaterials & Methods
Statistical tests usedStatistical tests used Chi square test for association between categorical Chi square test for association between categorical
variablesvariables Students t test Students t test Pearson’s correlation coefficientPearson’s correlation coefficient SPSS 12.0 softwareSPSS 12.0 software
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ObservationsObservations
Cases-25 Cases-25
Controls-14 Controls-14
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ObservationsObservations
Age distributionAge distribution
391425TOTAL
523More than 50
yrs
2281418-50 yrs
1248 Less than 18
yrs
TOTALCONTROLCASEAGEGROUP
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ObservationsObservations
Sex distributionSex distribution
391425TOTAL
716FEMALE
321319MALE
TOTALCONTROLCASESEX
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ObservationsObservations
Site of CSF SamplingSite of CSF Sampling
135
112
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0 5 10 15
LP
EVD
Lumbar Drain
CONTROL
CASE
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ObservationsObservations
FeverFever
10010Did not Subside
18315Subsided
28325PRESENT
TOTALCONTROLCASEFEVER
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Observations Observations
Incidence of positive cultureIncidence of positive culture
392910Total
14140Control
251510 (40 %)Case
TotalCulture -Culture +Category
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RESULTSRESULTS
Mean corrected WBC countMean corrected WBC count
0
100
200
300
400
500
600
700
Day 1 Day 3 Day 5/7
Day of analysisCases
Controls
0.0443312Day 5/7
0.556278371Day 3
0.547405609Day 1
Mean Corr WBC/mm3
2 tailed significance
CONTROLCASEDAY OFSAMPLING
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0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
Day 1 Day 3 Day 5/7
CSF:BLOOD GLUCOSE RATIO
Cases
Controls
.06.61.48Day 5/7
.002.62.38Day 3
.001.68.32Day 1
Mean CSF:Blood Glucose
2 tailed significance
CONTROLCASEDAY OFSAMPLING
Mean CSF: Blood glucose ratio
RESULTS
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CSF lactate values
4.436
3.571
5.0765.564
3.1573.257
0
1
2
3
4
5
6
7
Day 1 Day 3 Day 5/7
Cases
Controls
RESULTS
.2113.5714.436Day 5/7
.0003.1575.076Day 3
.0013.2575.56Day 1
Mean CSF Lactate values2 tailed significance
CONTROLCASEDAY OFSAMPLING
Mean CSF lactateMean CSF lactate
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CSF lactate trends in relation to culture positivity (n=cases)
4.587 4.053 3.6
7.03 6.615.68
0
2
4
6
8
10
Day 1 Day 3 Day 5/7
culturenegative
culturepositive
RESULTS
Mean CSF lactate trends correlated with culture positivity
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RESULTSRESULTS
5.7
3.5
5.15.6
4.95.6
0
1
2
3
4
5
6
Day 1 Day 3 Day 5/7
didn'trespond
respond
Mean CSF lactate trends correlated with subsidence of fever
.0053.55.7Day 5/7
.425.14.9Day 3
.9975.65.6Day 1
Mean CSF Lactate values
2 tailed significance
RespondedDidn’t respondDAY OFSAMPLING
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RESULTSRESULTS
CULTURE -
251510Total
990Combination -
16610Combination +
TOTALCULTURE +
Combination of CSF lactate>5.0 and Sugar ratio < 0.4
Senstivity = 100% , specificity = 60%
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RESULTSRESULTS
CULTURE -
251015Total
16511WBC -
954WBC +
TOTALCULTURE +
Conventional CSF analysis (CSF WBC >500/cumm)
Senstivity = 27% , specificity = 50%
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DiscussionDiscussion
High CSF lactate levels suggestive of infectionHigh CSF lactate levels suggestive of infection Can be easily determined in an ABG machine Can be easily determined in an ABG machine
with good agreement with standard lab values.with good agreement with standard lab values. In combination with low CSF: blood sugar ratio, In combination with low CSF: blood sugar ratio,
CSF lactate carries high sensitivity and specificity CSF lactate carries high sensitivity and specificity
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CONCLUSIONSCONCLUSIONS
CSF lactate can be used as single valid parameter CSF lactate can be used as single valid parameter in the diagnosis of meningitis.in the diagnosis of meningitis.
Initial baseline determination can be used to Initial baseline determination can be used to monitor therapy.monitor therapy.
Rapid and reliable diagnosis.Rapid and reliable diagnosis.
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Thank YouThank You