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Regional Anesthesia

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Regional anesthesia involves numbing a specific area of the body, without affecting either the brain or breathing. In a hip replacement the area covered will be the hip joint, buttock and front and back of the thigh.

With just a regional anesthetic you will be awake during surgery so a sedative, such as benzodiazepines, or a low concentration of a general will be given. Either will relax you and put into a light sleep. However, some people chose to stay awake and chose to have no sedation.

Types of regional anesthesia blocks

The most commonly used regional blocks are a) an epidural block (single shot or continuous injection) or b) spinal block (single shot of continuous injection). Other blocks do exist e.g. continuous lumbar plexus blockade and continuous peripheral blockade but are currently still under development and won't be discussed here at this time.

Spinal Block

Also referred to as spinal anesthesia, spinal analgesia or sub-arachnoid block (SAB)

A spinal block involves injecting the anesthetic into the fluid surrounding the spinal cord in the lower part of the back (the subarachnoid space). This produces a rapid numbing effect that can last for hours, depending on the drug used.

Bupivacaine is the local anesthetic most commonly used. Sometimes a vasoconstrictor such as epinephrine is added to the local anesthetic to prolong its duration. Recently, many anesthesiologists are choosing to add opioids such as morphine, or non-opioids like clonidine, to the local anesthetic. These provide prolonged pain relief (analgesia) once the action of the spinal block has worn off.

Epidural Block

An epidural block uses a small tube (catheter) inserted in your lower back to deliver the anesthetic over a longer time period. The most frequently used one is bupivacaine.

Both types of block are administered in a very similar location; however, the epidural catheter is placed slightly closer to the skin and farther from the spinal cord. The block can be provided in small doses to achieve an anesthetic effect over a long period. Indeed the epidural catheter can be left in place and anesthesia continued after the surgery has finished to help control pain. Normally the patient is given control of the dose received, within preset limits.

Advantages of a regional block

The use of epidural or spinal anesthesia during hip surgery has been linked to: -

• reduced risk of perioperative complications like deep venous thrombosis (DVT)
• less deterioration of cerebral and pulmonary functions in patients who are at high risk for complications, and
• overall reduced blood loss.
• effective and safe postoperative pain control(allowing for lower opioid consumption and improved and earlier rehabilitation).
• High patient satisfaction.

Complications of regional anesthesia

Side effects from regional anesthesia include: -

• headaches
• trouble urinating - a catheter may be used to manage urinary incontinence
• allergic reactions - which are rare. These may occur as the anesthetic is given before the start of surgery. The allergic reaction produced consists of itching, swelling, elevated temperature, respiratory distress, increased heart beat, anxiety and in the worst case death. However every operating theater is fully equipped to deal with allergic reactions and will have an anaphylactic kit present.

Combination of general and regional anesthesia

This is now the preferred method of anesthesia used during hip replacement surgery. There are fewer anesthetic induced side effects and greater post-operative analgesia. Indeed it now understood that preemptive pain management reduces the level of pain experienced in the days and weeks following surgery - allowing for an earlier discharge.

As the patient is in less pain they are also more able to participate in physical therapy which, in turn, increases their rate of recovery.

The combination of regional and light general is also significantly cheaper than using a general anesthetic alone.

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For more information on anesthesia check out the Royal Collage of Anaesthetists patient information

Related Links: 

Preparing for Surgery 
Surgical Approaches 
Preparing for Recovery

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