We compared the systemic toxicity of bupivacaine, levobupivacaine, and ropivacaine in anesthetized rats. We also compared the ability to resuscitate rats after lethal doses of these local anesthetics. Bupivacaine, levobupivacaine, or ropivacaine was infused at a rate of 2 mg. kg(-1). min(-1) while electrocardiogram, electroencephalogram, and arterial pressure were continuously monitored. When asystole was recorded, drug infusion was stopped and a resuscitation sequence was begun. Epinephrine 0.01 mg/kg was administered at 1-min intervals while external cardiac compressions were applied. Resuscitation was considered successful when a systolic arterial pressure > or =100 mm Hg was achieved within 5 min. The cumulative doses of levobupivacaine and ropivacaine that produced seizures were similar and were larger than those of bupivacaine. The cumulative doses of levobupivacaine that produced dysrhythmias and asystole were smaller than the corresponding doses of ropivacaine, but they were larger than those of bupivacaine. The number of successful resuscitations did not differ among groups. However, a smaller dose of epinephrine was required in the Ropivacaine group than in the other groups. We conclude that the systemic toxicity of levobupivacaine is intermediate between that of ropivacaine and bupivacaine when administered at the same rate and that ropivacaine-induced cardiac arrest appears to be more susceptible to treatment than that induced by bupivacaine or levobupivacaine.

We examined the effect of dextran (molecular weight 71,000) in counteracting the surfactant inhibitory action of plasma albumin. The surface adsorption time of 0.5 mg/ml modified natural surfactant (MNS; porcine lung extract consisting of phospholipids and hydrophobic surfactant proteins) with 7.5 mg/ml albumin decreased from 681 to 143 s by addition of dextran at a concentration of 10 mg/ml (P < 0.01). The minimum surface tension of 2.0 mg/ml MNS with 30 mg/ml albumin decreased from over 21 mN/m to below 3 mN/m when dextran was added at a concentration of 10 mg/ml (P < 0.01). Surfactant-deficient newborn rabbits given 10 ml/kg of a liquid containing 2.0 mg/ml MNS with 30 mg/ml albumin had a mean tidal volume 13 ml/kg (P < 0.05). Although the underlying mechanism remains to be elucidated, we conclude that dextran restores the albumin-inhibited surface activity of MNS.

The left-molar approach with OELM improves the laryngeal view in patients with difficult laryngoscopy.

Although in 15% of patients indirect laryngoscopy could not be performed because of excessive gag reflex, indirect laryngoscopy can serve as an effective method to predict difficult intubation.