Final answer:
The best option for an IV regional anesthesia for a hand surgery in a 68-year-old man would be E. 50 mL of 0.5% lidocaine, as this provides an adequate amount of anesthetic to ensure both efficacy and safety within the maximal recommended dose limits.
Step-by-step explanation:
To provide safe and reliable surgical anesthesia for the hand during the procedure to release trigger fingers in a 68-year-old man, option E. 50 mL of 0.5% lidocaine would typically be selected. Intravenous regional anesthesia, also known as a Bier block, involves injecting local anesthetic into a vein of an extremity with a tourniquet applied to prevent systemic distribution of the drug. The chosen concentration and volume of the local anesthetic must be sufficient to provide anesthesia while remaining within safe limits to avoid toxicity.
Lidocaine is frequently used for IV regional anesthesia because it has a rapid onset of action and a safety profile that is well suited for procedures lasting up to 1-2 hours, which matches the surgeon's estimated time for this hand surgery. The concentration of 0.5% lidocaine in a 50 mL volume provides an adequate amount of anesthetic to ensure both efficacy and safety, as larger volumes of dilute concentrations are preferred for IV regional anesthesia to cover the extensive sensory area of the hand.
It is important not to exceed recommended doses; for lidocaine, the maximal recommended dose without epinephrine is typically 4.5 mg/kg,a and with epinephrine is usually around 7 mg/kg. With this patient's weight of 80 kg, the maximum safe dose without epinephrine would be 360 mg, and option E provides exactly 250 mg of lidocaine (50 mL × 0.5% = 250 mg), which is within the safe limits. The other options provide either an insufficient volume or concentration for effective hand anesthesia or exceed toxicity thresholds.