[Comparison of 2 devices to measure spinal fluid glucose concentration in hyperbaric spinal anesthesia]. / Comparación de dos sistemas de medida de las concentraciones de glucosa en líquido cefalorraquídeo en la anestesia intradural hiperbara.

OBJECTIVES: To compare spinal fluid glucose measurements recorded by the laboratory analyzer Synchron LX20 Pro and the glucometer Ascensia Elite XL during continuous spinal anesthesia after injection of 10 mg of hyperbaric bupivacaine, in order to assess the reliability and speed of the 2 devices for monitoring changes in glucose concentration. PATIENTS AND METHODS: Prospective study of 34 patients under continuous spinal anesthesia administered through a 22-gauge catheter; 9 samples of spinal fluid were extracted from each patient for glucose level measurement. The first extraction was before administration of the anesthetic and the remaining ones were during spinal anesthesia until the end of complete motor block. Correlation was assessed with the Pearson test and agreement with the Bland-Altman method. RESULTS: A total of 241 pairs of measurements were obtained. The correlation was r = 0.96 (P < .01). The mean (SD) difference in measurements from the 2 devices was -1.06 (34.82 mg x dL(-1)). The percentage of variation (systematic error) was -1.9% (11.8%), placing the 95% confidence interval between -25% and 21.2%. CONCLUSIONS: Measurements from the 2 devices are highly correlated. The absolute and percentage systematic error (bias) is negligible. Finding that 95% of measurements are within 23% of the mean seems a fair percentage of error to us. We therefore believe the percentage variation, or systematic error, is clinically acceptable and that either device can be used.

Comparación de dos sistemas de medida de las concentraciones de glucosa en líquido cefalorraquídeo en la anestesia intradural hiperbara / Comparison of 2 devices to measure spinal fluid glucose concentration in hyperbaric spinal anesthesia

OBJETIVOS: Comparar las mediciones de glucorraquia realizadas en el Laboratorio con el autoanalizador Synchron LX20 PRO(R) (Beckman Coulter) con las realizadas con un glucómetro Ascensia EliteXL&Elite(R) durante la anestesia espinal, después de administrar 10 mg de bupivacaína hiperbara para así disponer de un método rápido y fiable al medir las cifras de glucorraquia durante una anestesia espinal continua y seguir su evolución. PACIENTES Y MÉTODOS: Estudio prospectivo de 34 pacientes bajo anestesia espinal continua con un catéter 22 G a través del cual se extrajeron 9 muestras por paciente de líquido cefalorraquídeo para determinar la glucorraquia, la primera antes de la administración del anestésico y los siguientes durante la anestesia espinal hasta el final del bloqueo motor completo. La correlación se midió con el test de Pearson y el grado de concordancia con el método de Bland-Altman. RESULTADOS: Se obtuvieron 241 pares de medidas. El coeficiente de correlación fue de r = 0,96 (p < 0,01). La diferencia media entre los dos métodos fue de –1,06 ± 34,82 mg dL–1. El porcentaje de variación (error sistemático) fue de –1,9 ± 11,8%, situándose el intervalo de confianza del 95% entre el –25% y el 21,2%. CONCLUSIONES: Se obtiene una buena correlación entre ambos métodos. El error sistemático absoluto y porcentual (bias), es despreciable. Encontrar el 95% de los valores con un margen de un 23% sobre la media del error porcentual nos parece razonable, por lo que consideramos la variación porcentual del error sistemático clínicamente aceptable para poder intercambiar ambos métodos de medida

OBJECTIVES: To compare spinal fluid glucose measurements recorded by the laboratory analyzer Synchron LX20 Pro and the glucometer Ascensia Elite XL during continuous spinal anesthesia after injection of 10 mg of hyperbaric bupivacaine, in order to assess the reliability and speed of the 2 devices for monitoring changes in glucose concentration. PATIENTS AND METHODS: Prospective study of 34 patients under continuous spinal anesthesia administered through a 22-gauge catheter; 9 samples of spinal fluid were extracted from each patient for glucose level measurement. The first extraction was before administration of the anesthetic and the remaining ones were during spinal anesthesia until the end of complete motor block. Correlation was assessed with the Pearson test and agreement with the Bland-Altman method. RESULTS: A total of 241 pairs of measurements were obtained. The correlation was r=0.96 (P<.01). The mean (SD) difference in measurements from the 2 devices was –1.06 (34.82 mg·dL-1). The percentage of variation (systematic error) was –1.9% (11.8%), placing the 95% confidence interval between -25% and 21.2%. CONCLUSIONS: Measurements from the 2 devices are highly correlated. The absolute and percentage systematic error (bias) is negligible. Finding that 95% of measurements are within 23% of the mean seems a fair percentage of error to us. We therefore believe the percentage variation, or systematic error, is clinically acceptable and that either device can be used

[Relation between glucose concentrations in cerebrospinal fluid and sensory and motor block during spinal anesthesia with hyperbaric bupivacaine]. / Relación de los niveles de la glucorraquia con el bloqueo sensitivo y motor durante la anestesia raquídea con bupivacaína hiperbara.

OBJECTIVE: To study the relation between cerebrospinal fluid (CSF) glucose levels, the highest level of sensory block, and the duration of motor block after intrathecal injection of 2 mL of hyperbaric bupivacaine. To determine CSF glucose levels upon recovery from motor block. PATIENTS AND METHODS: A prospective study of 34 patients administered a spinal anesthetic in continuous infusion through a 22-gauge catheter. CSF samples were extracted through the catheter 5, 10, 15, 20, 30, 45, and 60 minutes after start of infusion and upon motor recovery. After each extraction the intensity of the motor block was assessed; the intensity of the sensory block was assessed after each extraction up to 20 minutes. RESULTS: Glucose concentrations in CSF tended to decrease from 5 minutes (1027.07 [SD 349.04] mg dL(-1)) until full motor recovery (247.50 [20.39] mg dL(-1)). The probability of finding a motor block at a CSF glucose concentration of 287.5 mg dL(-1) or higher was less than 5%. We identified a positive correlation between the highest level of sensory block and the duration of full motor block (r=0.62, P<0.01) and between CSF glucose levels at the moment of greatest sensory block and upon full motor recovery (r=0.50, P<0.01). CONCLUSIONS: After continuous spinal anesthesia with hyperbaric bupivacaine, glucose concentrations in CSF are directly related to the highest level of sensory block, the course of the blockade, and its reversal.