What are the advantages and disadvantages of the various anesthetic options?
General anesthesia allows for excellent muscle relax-ation and a secure airway. Also, the anesthetic can be con-tinued for as long as the procedure lasts. However, it necessitates multiple drugs and may foster hemodynamic instability. There is also a strong possibility of the patient incurring postoperative nausea and vomiting from volatile agents, opioids, and reversal agents, and a sore throat if tra-cheal intubation is performed.
Spinal anesthesia also provides excellent muscle relax-ation, but like general anesthesia may cause hemodynamic instability. While general anesthesia can continue indefi-nitely, a spinal anesthetic will only last a finite amount of time (as spinal catheters are not utilized currently) and may wear off in the middle of a case, necessitating conver-sion to a general anesthetic. Intrathecal morphine can provide excellent postoperative pain relief but requires appropriate monitoring. Other complications associated with spinal anesthesia include but are not limited to postdural puncture headache, back pain, transient neu-ropathies, and the rare but devastating consequence of epidural abscess and hematoma.
Epidural anesthesia can be titrated to allow for better hemodynamic stability. If a catheter is placed, the anes-thetic can be prolonged for an indefinite period of time. A catheter can also be utilized for postoperative pain control. Onset is significantly slower than for spinal anes-thesia and at times muscle relaxation may not be adequate, especially when there is a “patchy” block. An epidural, like a spinal, carries the risk of neurologic complications, headache, back pain, infection, and hematoma.
Both spinal and epidural anesthesia seem to decrease the risk of deep vein thrombosis in the lower extremity.
A combined spinal/epidural technique provides the excellent muscle relaxation and quick onset of spinal anes-thesia and the ability to provide anesthesia indefinitely by placement of the epidural catheter. A disadvantage of this technique, however, is that the efficacy of the epidural catheter cannot be tested until the spinal anesthetic has begun to recede. If the catheter is non-functional, this would necessitate converting to a general anesthetic in the middle of the surgical procedure.
Femoral and sciatic nerve blocks, while somewhat time-consuming to perform, in experienced hands proba-bly take as long as the performance of a difficult spinal anesthetic. These nerve blocks, like neuraxial anesthetics, obviate the need for the polypharmacy associated with general anesthesia and at the same time allow for greater hemodynamic stability compared with neuraxial anesthe-sia. The placement of femoral and sciatic nerve catheters allow for the provision of excellent postoperative pain control.