Introduction
Labor pain is one of the most intense pains that women can experience. Most of the women state it as unbearable or intolerable pain. Labor pains can be characterized as continuous painful uterine contractions associated with the cervix's dilation. It is one of the most intense pain and, to overcome this pain, the doctor uses analgesics (painkillers) to control the labor pains. So that further delivery can be easily performed.
What Should Labor Analgesia Have?
A few ideal points to consider in labor analgesia are:
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It should be safe for both mothers and infants.
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It should not interfere with the process of delivery.
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It should provide flexibility in response to changing conditions.
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It should provide consistent pain relief.
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It should have a good and long duration of action.
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It should report minimum side effects.
What Are Spinal Blocks?
A spinal block is given to numb the nerves of the spinal cord. The injection for the block is delivered at the spinal sac (subarachnoid space) in the spinal cord. Therefore, the block is also called the subarachnoid block. The spinal block technique blocks the nerve of the buttocks, legs, and lower back, as the doctor gives the injection to the lumbar area of the lower back region. Spinal block is a type of regional anesthesia (a type of anesthesia to numb a particular body part rather than anesthetize the whole body). It is used alone or in combination with other anesthesia medicines or techniques. Spinal and epidural anesthesia (a method of injecting anesthetic medicine in the epidural space in the spinal cord) can work together in cases of Cesarean section. A spinal block injection contains both an anesthetic agent and an opioid to numb the area.
What Are the Local Anesthetic Agents Used in Spinal Blocks?
Local anesthetic agents used in spinal analgesia are:
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Lignocaine - It has a rapid onset of action. It can block the dense motor nerves, but it can cause a risk of cumulative toxicity (severe toxicity from the beginning of injection).
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Bupivacaine - It is a good anesthetic agent to block the sensory nerves. It is used less to block the motor nerves. It is safe for labor as no adverse effects are reported related to Bupivacaine.
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Ropivacaine - It has a low level of toxicity and can work less over the motor nerves. However, it is less potent.
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Levobupivacaine - It has lesser toxicity than Bupivacaine.
What Is the Opioid Used in the Spinal Blocks?
Opioids are drugs that are used to suppress pain as they work on nerve sensations and block neurotransmitter release. The opioid used in spinal blocks are:
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Morphine.
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Fentanyl.
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Sufentanil.
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Meperidine.
How Are Single-Shot Spinal Blocks Performed?
Spinal blocks are performed as follows:
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Initially, the doctor relaxes the patient and makes the patient sit or lie on the bed.
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The patient's position is important to create a straight path for the needle to reach the spinal sac. Most patients are made to sit for easy access.
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After the patient is positioned, the doctor locates the site to insert the needle.
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Before insertion, the doctor cleans the area with an antiseptic solution to disinfect the skin.
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Local anesthesia (usually Lignocaine) is used for skin infiltration.
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After infiltration, the needle is prepared to insert into the skin. The needle passes the outer skin to the fatty layer under the skin into the spinal ligaments.
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The needle is inserted deep into the skin to reach the spinal sac. An in-depth passage for spinal blocks is made; the needle reaches the subarachnoid area, which is the site for depositing the spinal block and the medicine is injected.
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After the deposition of the anesthetic agent, the needle is removed, and the site is bandaged.
What Happens After the Single Shot of a Spinal Block?
Immediately after the anesthetic agent deposition, it takes nearly five minutes for the anesthetic agent to relieve the patient's pain. Next, the patient starts feeling a warm sensation over the legs, and soon numbness will initiate, and the patient's pain will be inhibited. The whole pain relief process remains for two to four hours; after that, the body begins to feel sensation and the legs can move. After all this, the doctor uses a painkiller tablet to control further the pain after the spinal anesthesia wears off.
How Do Single-Shot Spinal Blocks Work for Labor Pains?
Single-shot spinal blocks are single injection doses delivered near the spinal nerves. It helps to control the pain felt by the patient. It can work for two to three hours to control the labor pain of the patient. Still, after two hours, a single-shot spinal block injection generally vanishes, and soon the patient begins to feel a painful sensation. It has a definite but rapid duration of action and has effective results for a particular time.
Advantages of Single-Shot Spinal Blocks for Labor Analgesia
The advantages of the single-shot spinal blocks for labor analgesia are:
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It causes the least depressing effect.
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It has a rapid duration of onset.
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It decreases maternal catecholamines (the hormone that takes part in high blood pressure and stress).
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It also improves uteroplacental perfusion (helps to deliver nutrition to the fetus).
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It does not have any effect on the uterus of pregnant women.
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It does not cause any harm to the baby of the pregnant woman.
What Are the Cases When Single-Shot Spinal Blocks Cannot be Used?
A single-shot spinal block cannot be used in cases like:
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It is not delivered if the patient refuses to have spinal blocks.
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Spinal blocks are not delivered when the patient suffers a systemic infection.
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Spinal blocks cannot be used in cases of neurological deficiency.
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It is not given if the patient suffers from hypovolemic shock (occurs due to a major blood vessel burst or injured).
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It is not given if any infection is present over the injection site.
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It is not used if there is increased intracranial pressure.
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It is not used in conditions like thrombocytopenia (deficiency of platelets in the blood).
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If the patient is suffering from any heart disease.
Complications related to single-shot spinal blocks are:
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Swelling over the site of injection.
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Hypotension (low blood pressure).
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Nausea and vomiting.
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Spinal hematoma (accumulation of blood in the spinal area).
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Arachnoiditis is the infection of subarachnoid spaces.
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Neurological injury.
Conclusion
Single-shot spinal blocks are used during labor to control the unbearable labor pains. Spinal blocks are usually delivered in a single shot, whereas epidurals are provided by the catheter inserted during the labor and delivery. Single-shot spinal blocks have a rapid duration of onset and present effective results within a particular time, after which the spinal wears off its effect. Though it has a limited action time, it provides a pain-free situation for the mother to undergo the procedure without unwanted complications.
