Glucose Concentration in Cerebrospinal Fluid
as Predictor of Sensory Block Quality
during Spinal Anesthesia in Clinical Practice

Möllmann M, Raabe B, Cord S, Lahme T, Holst D (1999)

posterpresentation,
ASRA Annual Meeting and Workshop,
May 6-9, 1999, Philadelphia/PA, USA,
American Society of Regional Anesthesia and Pain Medicine

Goal of study:
- Variablity in lumbosacral cerebrospinal fluid (LS-CSF) volume among individuals is regarded as the deciding factor that leads to spinal sensory anesthesia of unpredictable extent and duration (1).
- As LS-CSF volume could not be predicted by readily available patient characteristics yet; uncertainty seemed inevitable after intrathecal injection of a single anesthetic dose.
- The aim of this prospective study was to determine whether the change of glucose concentration after  administration of glucose free solution can predict the volume of LS-CSF and thus predict the spread of the sensory block extent.

Methods:
- 25 patients who underwent minor onthopedic or vascular sugerv received spinal anesthesia with 2 or 3 ml plain bupivacaine (bv) 0.5%.
- Before the   local anesthetic was administered, 1 ml of LS-CSF was aspirated and glucose concentration was determined by glucose-oxidation (GOD).
- Two minutes after 0.5% bv had been injected, a new LS-CSF sample was gained and glucose concentration was measured again.
- The difference of glucose concentration in LS-CSF was regarded as a parameter of real distribution area of bv.
- The extent of sensory anesthesia was assessed with pin prick at 10 min after the intrathecal injection of 0.5% bv.

Results:
- In 25 patients all parameters could be determined; no difference in demographics was noted:

- Differences of glucose concentration in LS­CSF were found from 6 - 32 mg/dl.
- Peak sensory height reported from the patients ranged from L3 to Th3.

Conclusions:
- The decrease of LS-CSF glucose concentration after administration of glucose free local anesthetic depends on the real existing distribution area (high glucose concentration differences coincide with a low distribution area).
- Therefore  we  correlated  decrease  of glucose  concentration  and  spread  of anesthesia.
- We found that differences in  LS-CSF glucose concentration correlate with the achieved peak sensory block height and thus do provide a possibility to determine LS-CSF volume in an easy and practical way.
- Therefore, extent and duration of neural blockade in the individual patient produced by a defined volume of local anesthetic become more predictable under routine conditions using continuous spinal anesthesia.