Comparative study on anesthetic potency depending on concentrations of lidocaine and epinephrine: assessment of dental local anesthetics using the jaw-opening reflex.

Anesthetic potency of a local anesthetic on the dental pulp was investigated by increasing or decreasing the concentration of lidocaine and that of epinephrine. An electromyogram of the digastric muscle in Japan White male rabbits was recorded during the jaw-opening reflex induced by electrical stimulation of the dental pulp. Probit analysis was used for the determination of the 50% effective volume (ED50) values of the anesthetic. The anesthetics used were plain 2% lidocaine solution (2Lid-0 group), 2% lidocaine solution with 12.5 microgram/mL of epinephrine (2Lid-1/8 group), 2% lidocaine solution with 6.25 microgram/mL of epinephrine (2Lid-1/16 group), and 4% lidocaine solution with 5 microgram/mL of epinephrine (4Lid-1/20 group). No anesthetic effect was shown in the 2Lid-0 group. The 2Lid-1/8 group indicated adequate anesthetic potency with the smallest dosage at all observation periods. The potency in the 2Lid-1/16 group was 0.3-0.5 times, and that in the 4Lid-1/20 group was 0.3-0.4 times as much as the 2Lid-1/8 group. The decrease in epinephrine concentration produced the decrease in the anesthetic potency on the dental pulp independent of lidocaine concentration. These results suggest that the increase in lidocaine concentration may not compensate the decrease in epinephrine concentration.

[Anesthetic management for neonates with congenital cystic adenomatoid malformation].

We experienced two cases of congenital cystic adenomatoid malformation (CCAM) diagnosed by prenatal ultrasonography. The first case with type I CCAM underwent the resection of the right upper lobe 8 days after birth. Postoperative course was uneventful. The second case with type III CCAM developed non-immune hydrops, severe mediastinal shift, and polyhydroamnios at 29 weeks' gestation. At 30 weeks' gestation, cesarean section was performed. Immediately after birth, the resection of lung tumor for the neonate was performed. However, the neonate died on the 1st postoperative day.

[Combined intercostal nerve block and epidural anesthesia in a patient with severe aortitis syndrome].

A 74-year-old woman with aortitis syndrome was scheduled for mastectomy. Her left vertebral artery was totally occluded and left carotid arteries, left subclavia artery and bilateral common renal arteries were occluded. For anesthesia a catheter was inserted into the epidural space between T3 and T4. Lidocaine 80 mg (2%, 4 ml) was administered epidurally. Then intercostal nerve block was performed with bupivacaine 15 mg (0.5%, 3 ml) at T3 and T4 level. Local infiltration of lidocaine 50 mg (1%, 5 ml) was added. During the surgery, hemodynamics were stable and no neurological symptom was observed. Epidural anesthesia alone might be sufficient for anesthesia if higher concentration of local anesthetic was used. However, to avoid hemodynamic change, we used 1% lidocaine and added intercostal nerve block. We conclude that combined intercostal nerve block and epidural anesthesia was useful for a patient with severe aortitis syndrome in oder to monitor consciousness to detect cerebral ischemia and to avoid hemodynamic instability.