Fast glycorrhachia and cerebrospinal fluid protein as predictors of sensory block in anesthesia with subarachnoid Ropivacaine.

BACKGROUND: Identify if glycorrhachia and cerebrospinal fluid protein could influence the time of sensory block to T10, the duration and the metameric block's level, after a standard dose of Ropivacaine. METHODS: 80 patients, ASA I - III undergoing to transurethral prostate resection with spinal anesthesia in a prospected open study were recruited. A 0.2 ml liquor's sample was taken; glycorrhachia, by glycemic stix and CSF protein, by urinary stix, were got, before Ropivacaine 0.5% 15 mg injection (0.10 - 0.15 mlsec). After anti-trendelemburg, with 30 ° tilting for 15 min, the onset of sensory block to T10, the maximum metameric level to 15' and the time of sensory block were reported. The data collection were analyzed using the software language R. RESULTS: A significant correlation liquor specific weigh preoperative glycemia (0.749), liquoral specific weigh glycorrhachia (rho = 0.751; R2 = 0.564; P 0.05) and specific weigh CSF protein (rho = 0.684; R2 = 0.468; P 0.05) were reported. Inverse relation CSF weightsensory block level (rho -0.789, P 0.05, R2 0.621) was evidenced. Inverse relation onset time to T10 glycorrhachia (84%) and cephalic block glycorrhachia (76%) were found. Inverse correlation onset time to T 10 CSF protein and cephalic block proteinorrachia was respectively 84% and 67%. A rho of 0.712 with R2 of 51% BMI onset to T10 and rho of 0.681 with R2 of 51% BMI maximum cephalic block with P 0.05 were reported. CONCLUSIONS: The predictability of a iso-hypobaric local anesthetic could reduce the risk of procedure failure and adverse events by further cephalic spread.

Correlation between glucose and bupivacaine levels in cerebrospinal fluid after spinal anesthesia: glycorrhachia as predictor for duration of sensory block.

BACKGROUND: Prediction of the duration of motor block after injection of a local anesthetic into cerebrospinal fluid (CSF) would be a very useful tool in clinical practice. However, previous attempts have not shown conclusive results. In this work, glycorrhachia is demonstrated to be an adequate predictive parameter after spinal anesthesia using 0.5% hyperbaric bupivacaine. METHODS: Two mL of local anesthetic through a continuous spinal catheter was administered to 40 patients. CSF was sampled at different time intervals from the onset of infusion to motor recovery. CSF bupivacaine concentrations were measured using chromatography. An automated analyzer was used for determining glycorrhachia in the same samples. RESULTS: For all patients, good correlation (r(2)>0.95, p<0.05) was obtained. From these results, it was possible to develop a general model which establishes the relationship between CSF glucose and bupivacaine concentrations (R(2)=0.987, p<0.05). Motor block is reached when CSF glucose concentration is about 245 mg/dL (13.5 mmol/L), which corresponds to 35 microg/mL of bupivacaine. CONCLUSIONS: Glycorrhachia measured during surgical intervention in patients undergoing spinal anesthesia with hyperbaric bupivacaine provides a mechanism for predicting the duration of motor block in a rapid and simple manner.

Auditory evoked responses under total spinal anesthesia in rats.

In order to investigate the function of the auditory pathway from the cochlea to the brain stem under total spinal anesthesia, the auditory brain stem response (ABR), compound action potential of the cochlear nerve (CAP), and cochlear microphonics (CM) were simultaneously recorded in rats. Total spinal anesthesia was induced by infusion of 2% lidocaine hydrochloride at a constant rate of 0.10 mL/min into the cerebrospinal fluid through the rats' skulls. The ABR completely disappeared within 1.5 to 4 minutes. After cessation of the injection, the ABR reappeared, starting from wave I and progressing through waves II and III to wave IV. The latency change of the CAP throughout the recording period was quite similar to that of wave I of the ABR. A reduction in amplitude of the CM was observed, but the CM did not disappear during the recording period. Disappearance of the ABR was due, not to loss of cochlear function, but to anesthetic effects on the acoustic nerve and the brain stem. Monitoring of the ABR provided information on the level of neural activity in the brain stem under total spinal anesthesia.