Mepivacaine for spinal anesthesia in parturients undergoing elective cesarean delivery: maternal and neonatal plasma concentrations and neonatal outcome.

OBJECTIVE: Worldwide, long-acting bupivacaine is most commonly used for spinal anesthesia in parturients undergoing elective Cesarean delivery. However, advances in surgical technique and shorter duration of surgery make short-acting local anesthetic like mepivacaine appropriate, particularly if combined with opioids to enhance postoperative maternal pain relief. MATERIAL AND METHODS: We assessed the effect of 4% hyperbaric mepivacaine (60 mg) plus 10 microg fentanyl for spinal anesthesia in 11 parturients undergoing elective Cesarean delivery. Sensory, motor and analgesic block characteristics, neonatal outcome (Apgar scores, umbilical cord blood analysis, neurologic and adaptive capacity score) as well as fetal and maternal mepivacaine plasma concentrations at delivery were determined (HPLC/UV). RESULTS: Motor block (Induction-Bromage 0) duration lasted 113 +/- 20 min. Effective analgesia (VAS < or = 40) was 128 +/- 35 min. Maternal and fetal mepivacaine free plasma concentration were 0.18 +/- 0.05 microg/ml and 0.10 +/- 0.03 microg/ml, respectively. The fetal to maternal (UV/MV)-ratio for mepivacaine free plasma concentration was 0.56. Apgar scores, NACScores and the umbilical blood analysis showed no evidence of neonatal depression. CONCLUSIONS: Particularly with short duration of surgery (21 +/- 5 min) intrathecal mepivacaine combined with fentanyl offers a favorable clinical alternative in parturients undergoing elective Cesarean delivery.

Compliance in anastomoses with and without vein cuff interposition.

OBJECTIVE: to compare anastomotic compliance in end-to-side anastomoses with and without vein cuff interposition. Materials polytetrafluoroethylene graft to bovine carotid artery without (standard) and with vein interposition (Linton-patch and Miller-cuff). METHODS: zonewise compliance measurement of end-to-side anastomoses in an in-vitro circulation system. The zone most distal to the suture-line served as reference compliance. RESULTS: directly distal to the suture-line the compliance of the Linton-patch (5.6+/-1.6%/100 mmHg) and Miller-cuff anastomosis (5.2+/-1.1%/100 mmHg) more closely approached reference compliance (standard: 5.0+/-1.2, Linton-patch: 4.5+/-1.5, Miller-cuff: 4.9+/-1.0%/100 mmHg) than that of the standard anastomosis (7.9+/-3.0%/100 mmHg). The maximal compliance values of the Linton-patch (9.5+/-2.3%/100 mmHg) and Miller-cuff anastomoses (9.8+/-2.7%/100 mmHg) were significantly higher than that of the standard end-to-side anastomosis (7.9+/-3.0%/100 mmHg). However, maximal compliance was shifted from the zone directly distal to the suture line in the standard end-to-side anastomosis, to the vein cuff interposition in the Linton-patch and Miller-cuff anastomoses. CONCLUSION: the shift in maximal compliance to the wider portion of the anastomosis in the Miller-cuff and Linton-patch anastomoses may obviate reocclusion.