Curtis L. Baysinger

Evaluation of Neurotoxicity after Subarachnoid Injection of Large Volumes of Local Anesthetic Solutions

Recent case reports describing prolonged neurologic deficit after accidental spinal anesthesia with large volumes of 2− chloroprocaine have led to the suggestion that chloroprocaine may be more likely to cause such complications than other local anesthetics. We evaluated the neurologic effects of lumbar puncture alone and of large-volume subarachnoid administration of 2-chloroprocaine (3%), bupivacaine (0.75%), lidocaine (2%), Elliotts solution B (which is similar to CSF), or the carrier solution of 2-chloroprocaine (Nesacaine) in 48 sheep and 8 monkeys. Cerebrospinal fluid of sheep was collected on days 1 and 7 for biochemical and biological analyses, and CSF pressures of monkeys were recorded before and after injection. Animals were observed for neurologic deficits for seven days. Twelve sheep were unable to stand. Monkeys, on the other hand, had no apparent neurologic deficits. Autopsies revealed that 5 of the 12 sheep had lumbar subpial demyelination with macro- phage infiltration: two of the five had received lidocaine; two received 2-chloroprocaine; and one had only a lumbar puncture. Two other sheep also had subpial demyelination: one had received lidocaine and one received 2-chloroprocaine. Three of the eight monkeys had lumbar subpial demyelination with macrophage invasion; two had received bupivacaine, and one received 2-chloroprocaine. No solution produced significant abnormalities in sheep CSF composition. We conclude that no local anesthetic or solution was more neurotoxic than another when injected in large volumes into the subarachnoid space of sheep or monkeys.

The successful treatment of dural puncture headache after failed epidural blood patch.

Puncture of the lumbar dura can lead to a severe and often incapacitating headache. A single injection of autologous blood into the epidural space relieves the headache in 90% of the patients so affected, whereas a second blood patch successfully treats the majority of those in whom the first blood patch is ineffective (1 ) . The management of patients in whom the repeat blood patch fails is not clear. We describe the effective treatment of postdural puncture headache in two patients using patient-controlled, continuous, epidural infusion of saline after failed epidural blood patch.

Epidural Hydromorphone With and Without Epinephrine for Post-operative Analgesia After Cesarean Delivery

The efficacy of epidural hydromorphone alone or in combination with epinephrine for postoperative analgesia was evaluated in 30 healthy women who underwent cesarean delivery with epidural anesthesia. They were assigned randomly to receive either 1.5 mg hydromorphone alone (N = 15) or 1.5 mg hydromorphone with 1/200,000 epinephrine (N = 15). Duration of analgesia (mean ± SD) was 24.3 ± 9.4 hours after the epidural injection of hydromorphone plus epinephrine. This was significantly greater (p < 0.01) than the duration of 18.2 ± 5.9 hours after the same dose of plain hydromorphone. Analgesia was more rapid in onset and significantly better at the 0.5, 1, 3, and 12 hours postoperatively in the hydromorphone-epinephrine group. Side effects including pruritus (73%), nausea (20%), and vomiting (15%) were of similar frequency with and without epinephrine. Although mean venous PCO2 (Pv,CO2) levels three and six hours after the hydromorphone-epinephrine dose were elevated significantly over the pre-drug PvCO2 levels, no respiratory depression was detected by an apnea monitor to which all patients were connected. The addition of epinephrine to epidural hydromorphone hastened onset and prolonged the duration of analgesia after cesarean section.

Imaging During Pregnancy

The use of imaging techniques in women who are pregnant has increased greatly over the past decade. This focused review discusses the risks and indications of ultrasonography, magnetic resonance imaging, computed tomographic scanning, and fluoroscopy for the evaluation of the parturient with non-obstetric disorders. Diagnostic imaging of the pregnant woman for the evaluation of disorders not related to pregnancy is evolving, and protocols will vary from institution to institution. The potential benefit from indicated diagnostic radiological procedures in the parturient nearly always outweighs risk to the fetus because radiation exposure from a single procedure conveys little fetal risk.

Evaluation of Neurotoxicity After Subarachnoid Injection of Large Volumes of Local Anesthetic Solutions

Recent case reports describing prolonged neurologic deficit after accidental spinal anesthesia with large volumes of 2− chloroprocaine have led to the suggestion that chloroprocaine may be more likely to cause such complications than other local anesthetics. We evaluated the neurologic effects of lumbar puncture alone and of large-volume subarachnoid administration of 2-chloroprocaine (3%), bupivacaine (0.75%), lidocaine (2%), Elliotts solution B (which is similar to CSF), or the carrier solution of 2-chloroprocaine (Nesacaine) in 48 sheep and 8 monkeys. Cerebrospinal fluid of sheep was collected on days 1 and 7 for biochemical and biological analyses, and CSF pressures of monkeys were recorded before and after injection. Animals were observed for neurologic deficits for seven days. Twelve sheep were unable to stand. Monkeys, on the other hand, had no apparent neurologic deficits. Autopsies revealed that 5 of the 12 sheep had lumbar subpial demyelination with macro- phage infiltration: two of the five had received lidocaine; two received 2-chloroprocaine; and one had only a lumbar puncture. Two other sheep also had subpial demyelination: one had received lidocaine and one received 2-chloroprocaine. Three of the eight monkeys had lumbar subpial demyelination with macrophage invasion; two had received bupivacaine, and one received 2-chloroprocaine. No solution produced significant abnormalities in sheep CSF composition. We conclude that no local anesthetic or solution was more neurotoxic than another when injected in large volumes into the subarachnoid space of sheep or monkeys.