Diagnosis of postoperative meningitis using CSF lactate

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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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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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Corrected CSF WBC countCorrected CSF WBC count

(WBC – (RBC /600))(WBC – (RBC /600))

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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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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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Age distributionAge distribution

391425TOTAL

523More than 50

yrs

2281418-50 yrs

1248 Less than 18

yrs

TOTALCONTROLCASEAGEGROUP

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Sex distributionSex distribution

391425TOTAL

716FEMALE

321319MALE

TOTALCONTROLCASESEX

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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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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



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


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


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

Diagnosis of postoperative meningitis using CSF lactate

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