A spinal block is a type of short anesthetic treatment that may completely reduce sensation from the point of injection in the spine, at just above the hips, down to the feet. People use spinal blocks as a means of reducing pain for chronic medical conditions or lower back injuries.
Bupivacaine Marcaine is the local anesthetic most commonly used; lidocaine , tetracaine , procaine , ropivacaine, levobupivicaine and cinchocaine are also available. Sometimes a vasoconstrictor such as epinephrine is added to the local anesthetic to prolong its duration.
Of late, many anesthesiologists are preferring to add opioids like morphine, fentanyl or buprenorphine, or non-opioids like clonidine, to the local anesthetic used in spinal, to give a smoother 'effect' and to provide prolonged pain relief once the action of the 'spinal' has worn off. Regardless of the anesthetic agent drug used, the desired effect is to block the transmission of afferent nerve signals from peripheral nociceptors.
Sensory signals from the site are blocked, thereby eliminating pain. The degree of neuronal blockade depends on the amount and concentration of local anesthetic used, and the properties of the axon. Thin unmylenated C-fibres associated with pain are blocked first, while thick, heavily mylenated A-alpha motor neurons are blocked last. The desired result is total numbness of the area. A pressure sensation is permissible and often occurs due to incomplete blockade of the thicker A-beta mechnorecptors.
This allows surgical procedures to be performed with no painful sensation to the person undergoing the procedure. Some sedation is sometimes provided to help the patient relax and pass the time during the procedure, but with a successful spinal anesthetic the surgery can be performed with the patient wide awake. Spinal anesthetics are limited to procedures involving most structures below the upper abdomen.
To administer a spinal anesthetic to higher levels may affect the ability to breathe by paralyzing the intercostal respiratory muscles, or even the diaphragm in extreme cases called a "high spinal", or a "total spinal", with which consciousness is lost , as well as the body's ability to control the heart rate via the cardiac accelerator fibres.
Also, administration of spinal anesthesia higher than the level of L1 can cause damage to the spinal cord, and is therefore usually not done.
Can be broadly classified as immediate on the operating table or late in the ward or in the P. In both procedures there is risk for infection and chance that the dura will pierced, which can result in development of headaches that may come and go for months. Generally, greater potential problems result from an epidural including allergic reaction , though this may also occur to any anesthetic in a spinal block, back troubles, damage to nerves, and occasionally fever.
The term epidural is often short for epidural anesthesia, a form of regional anesthesia involving injection of drugs through a catheter placed into the epidural space. The injection can cause both a loss of sensation anesthesia and a loss of pain analgesia , by blocking the transmission of signals through nerves in or near the spinal cord.
The epidural space is the space inside the bony spinal canal but outside the membrane called the dura mater sometimes called the "dura". In contact with the inner surface of the dura is another membrane called the arachnoid mater "arachnoid".
The arachnoid encompasses the cerebrospinal fluid that surrounds the spinal cord. A patient receiving an epidural for pain relief typically receives a combination of local anesthetics and opioids. This combination works better than either type of drug used alone. Common local anesthetics include lidocaine , bupivacaine , ropivacaine , and chloroprocaine. Common opioids include morphine , fentanyl , sufentanil , and meperidine. These are injected in relatively small doses.
Occasionally other agents may be used, such as clonidine or ketamine. For a short procedure, the anesthetist may introduce a single dose of medication the "bolus" technique.
This will eventually wear off. Thereafter, the anesthetist may repeat the bolus provided the catheter remains undisturbed. For a prolonged effect, a continuous infusion of drugs may be employed.
Typically, the effects of the epidural are noted below a specific level on the body dermatome. This level the "block height" is chosen by the anesthetist.
The level is usually dermatomes higher than the point of insertion. A very high insertion level may result in sparing of very low dermatomes. For example, a thoracic epidural may be performed for upper abdominal surgery, but may not have any effect on the perineum area around the genitals or bladder.
Nonetheless, giving very large volumes into the epidural space may spread the block both higher and lower. The intensity of the block is determined by the concentration of local anesthetic drugs used. For example, 15 ml 0. Conversely, 15 ml of 0. Since the volume used in each case is the same, the spread of drug, and hence the block height, is likely to be similar.
Injecting medication into the epidural space is primarily performed for analgesia. This may be performed using a number of different techniques and for a variety of reasons. Additionally, some of the side-effects of epidural analgesia may be beneficial in some circumstances e.
When a catheter is placed into the epidural space a continuous infusion can be maintained for several days, if needed. Epidural analgesia may be used:. Whereas a spinal gives you pain relief for an hour or two, an epidural offers you the option of pain relief for a longer period of time. Learn more about the pros and cons of epidurals. There are births where a spinal has advantages over an epidural. If you experience any complications during birth or are having a cesarean delivery, also known as a C-section, your OB may advise you to opt for a spinal.
In these cases, you want immediate relief. In addition, by injecting anesthetics directly into the dural sac that contains cerebrospinal fluid, lower doses of medication can be used.
Both epidurals and spinals share the same amount of risk. Your medical team will monitor you closely, as the anesthetics that you receive also affect the central nervous system CNS , cardiovascular system, and respiratory system. Together, you make an informed decision. Just know that plans can change. You've seen the movies and heard the stories, but you want to know the details.
Is there a scale for the pain? How do contractions really feel? New moms-to-be often have a difficult time deciding between a no medication at all and getting an epidural during labor. Here are the pros and cons of…. Every delivery is as unique and individual as each mother and infant. Each woman may have a completely new experience with each labor and delivery. Spinal anesthesia numbs the body below and sometimes above the site of the injection.
The person may not be able to move his or her legs until the anesthetic wears off. A headache is the most common side effect of spinal anesthesia.
It can usually be treated easily. Headaches are less common with epidural anesthesia. Epidural and spinal anesthesia are usually combined with other medicines that make you relaxed or sleepy sedatives or relieve pain analgesics. These other medicines are often given through a vein intravenously, IV. Or they may be injected into the epidural space along with the local anesthetic.
You are monitored closely when receiving epidural or spinal anesthesia. That's because the anesthetics can affect the central nervous system, cardiovascular system, and respiratory system. Both spinal and epidural anesthesia may affect blood pressure, breathing, heartbeat, and other vital functions. Freedman MD - Anesthesiology. Author: Healthwise Staff. This information does not replace the advice of a doctor.
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