Peripheral vasodilation also occurs, worsening the hypotension. This may lead to complete cardiovascular collapse with no pulse, no blood pressure and no cardiac rhythm. For example, the dose needed for cardiovascular collapse divided by the dose needed for convulsions is 3.7 for bupivicaine, versus 7.1 for lidocaine. When bupivicaine toxicity occurs, it is more likely to result in ventricular arrhythmias than with other agents. As indicated, these arrhythmias are best treated with bretylium.
Pregnant women appear to be more sensitive to bupivicaine cardiac toxicity.
For example, epinephrine added to lidocaine used in the repair of a scalp wound can help reduce blood loss in this highly vascular area. There is, however, a downside to using epinephrine. First, when absorbed systematically it can cause hypertension, tachycardia and even arrhythmias, and this is obviously a potential concern in hypertensive patients or patients with coronary artery disease. Finally, epinephrine should not be used on digits, toes or on the penis because of concerns that ischemia may occur from vasoconstriction. When using local anesthesia in large amounts, always ensure that the patient has an intravenous line in place in case of local anaesthetic toxicity.