Anestesia

Epidural Anesthesia
Epidural anesthesia involves the use of local anesthetics injected into the epidural space to produce a reversible loss of sensation and motor function. Epidural anesthesia requires larger amounts of local anesthetic than a spinal anesthetic. Close attention to the total dose is required to avoid toxicity. Epidural anesthesia is versatile and can be administered by a singleinjection or through a catheter. The use of a catheter allows the anesthesia provider to add local anesthetics as surgery progresses, extending duration beyond the original dose. Epidural anesthesia can be combined with a general anesthetic or used as the sole anesthetic. In addition, the epidural catheter can be used for postoperative analgesia. Epidural anesthesia provides excellent operatingconditions for surgical procedures below the umbilicus. Procedures include:  cesarean section  procedures of the uterus, perineum*  hernia repairs  genitourinary procedures  lower extremity orthopedic procedures In addition, it is an excellent option for the elderly patient who may not tolerate a general anesthetic. It is important not to use an epidural anesthetic in patients who arehypovolemic or severely dehydrated. Patients receiving an epidural anesthetic should be preloaded with .5-1 liter of crystalloid solution, such as ringers lactate, immediately prior to the block. Epidural anesthesia has a higher rate of failure for surgical procedures in the perineal area. Lower lumbar and sacral nerve roots are large and there is an increase in the amount of epidural fat which can affectlocal anesthetic penetration and subsequent blockade. This phenomenon is known sacral nerve sparing.

Advantages of Epidural Anesthesia
Several advantages of neuraxial blockade were listed in the Introduction to Neuraxial Blockade section of this manual. Additional advantages specific to epidural anesthesia include: Easy to perform (though it takes a bit more practice than spinal anesthesia)Reliable form of anesthesia Provides excellent operating conditions The ability to administer additional local anesthetics increasing duration The ability to use the epidural catheter for postoperative analgesia Return of gastrointestinal function generally occurs faster than with general anesthesia Patent airway Fewer pulmonary complications compared to general anesthesia Decreased incidence of deepvein thrombosis and pulmonary emboli formation compared to general anesthesia

Disadvantages of Epidural Anesthesia

There are several disadvantages to epidural anesthesia including: Risk of block failure. The rate of failure is slightly higher than with a spinal anesthetic. Always be prepared to induce general anesthesia if block failure occurs. Onset is slower than with spinal anesthesia.May not be a good technique if the surgeon is impatient or there is little time to properly perform the procedure. Normal alteration in the patient’s blood pressure and potentially heart rate (generally slower onset with less alteration in blood pressure and heart rate than with a spinal anesthetic). It is essential to place the epidural block in the operating room/preoperative area withmonitoring of an ECG, blood pressure, and pulse oximetry. Resuscitation medications/equipment should be available. Risk of complications as outlined in Introduction to Neuraxial Blockade chapter. There is an increase in the complication rate compared to spinal anesthesia. Continuous epidural catheters should not be used on the ward if the patient’s vital signs are NOT closely monitored. Risk for infection,resulting in serious complications.

Contraindications

Please review chapter 2 for contraindications.

Site of Action for Local Anesthetics in the Epidural Space
The majority of the local anesthetic administered is absorbed systemically by the rich venous plexus found within the epidural space. Dura surrounding spinal nerve/nerve roots are a modest barrier to the spread of local...