Differential epidural block.

BACKGROUND AND OBJECTIVES: Loss of sensation to pinprick and cold are commonly used to test the extent of epidural anesthesia. To see what difference exists between the level of epidural block determined by various sensory modalities, we performed this study in ten volunteers using epidural anesthesia with plain 3% chloroprocaine hydrochloride. METHODS: Four injections of chloroprocaine were made via an epidural catheter inserted at L2-3 with increasing larger volumes. Sensory modalities tested were (1) absence of sensation when tested by pinprick (anesthesia), (2) loss of a sharp sensation compared to an unblocked dermatome when tested by pinprick (analgesia), and (3) loss of cold sensation when tested with an alcohol swab compared to an unblocked dermatome. RESULTS: At 20 minutes after each injection the level of anesthesia was found to be most caudad and the level of analgesia most cephalad. The zone of differential block was greater than four dermatomes at the highest level of block tested. The level of loss of cold sensation was found between the other two levels. Differences between the levels of analgesia and cold sensation tended to be greater with more extensive block. Differences between levels of anesthesia and cold sensation did not significantly change as the extent of epidural anesthesia was increased. CONCLUSIONS: This study establishes the existence of a differential epidural anesthesia during high thoracic block with chloroprocaine and suggests that the intensity of block diminishes as distance from site of injection increases.

Post dural puncture headache after lumbar sympathetic block: a report of two cases.

Dural puncture during lumbar sympathetic block (LSB) is a recognized but apparently uncommon complication. Interestingly, post dural puncture headache (PDPH) has not been reported as a complication of LSB. The authors report two cases of PDPH after LSB. In the first case an attempt to treat the PDPH with an epidural blood patch failed. In the second case the patient developed PDPH and a subdural block during separate LSBs. Possible anatomic explanations for these complications are discussed.

Back pain after epidural anesthesia with chloroprocaine in volunteers: preliminary report.

The incidence, character and treatment of backache associated with epidural anesthesia (EA) using 3% chloroprocaine (2-CP, Nesacaine-MPF) were observed in ten volunteers undergoing a study of the effects of EA upon plasma catecholamines. Three levels of epidural analgesia were sequentially sought, T10, T4 and C8, in ascending order. Each block was allowed to fully dissipate prior to the next injection. For the first, second and third injections, 15-20 ml, 25-35 ml and 52-60 ml, respectively, of 3% 2-CP were injected via an epidural catheter. Mean total volume of 2-CP injected was 103 ml (range, 92-115 ml) over seven hours. Back pain was first reported after as little as 15 ml (mean +/- SEM, 24.0 +/- 3.9 ml; range, 15-45 ml). The pain was described as a dull ache deep in the lumbar back, ranging in severity from mild to severe. No profound spasm of the erector spinae muscles was observed. Mean verbal analog scale pain scores after regression of the first, second and third blocks were 2.2, 4.3 and 6.5, respectively. Epidural fentanyl (100-200 micrograms) was effective in providing rapid relief of the pain. Large doses or possibly repeated injections of epidural Nesacaine-MPF are associated with an increased incidence and severity of postanesthesia lumbar back pain.

Changes in human plasma catecholamine concentrations during epidural anesthesia depend on the level of block.

To test the hypothesis that increasing levels of epidural analgesia will produce progressive decreases in circulating catecholamines, we sequentially produced three levels of analgesia, T8, T4, and C8, to pin prick in young, healthy volunteers. Three percent chloroprocaine (plain) was used as the local anesthetic. The epidural analgesia was allowed to dissipate following the T8 and T4 levels of block. After the C8 level the block was reinforced to study the effect of a "top-up" dose. Blood samples were drawn from a central venous catheter. Plasma concentrations of norepinephrine and epinephrine were determined by the single isotope radioenzymatic method. Despite extensive block, hemodynamic alterations were minimal, and no significant decrease in plasma epinephrine was observed as the level of analgesia was raised to the C8 dermatome. When the level of analgesia was raised above T8, there was a trend for norepinephrine to decrease, but this decrease did not become statistically significant until analgesia reached the C8 dermatome. Reinforcing the epidural block at the C8 level of analgesia resulted an insignificant decrease in epinephrine and norepinephrine NE. Under the conditions of the present study, epidural block with a sensory analgesia level as high as C8 did not significantly decrease the plasma concentration of epinephrine in unstressed volunteers. The plasma concentration of norepinephrine significantly decreased only when the level of sensory analgesia was approximately C8.