Epidural needle block complications

1. Perforating the dura mater

1. Reasons There are two reasons for the perforation of the dura mater, the operational factors and the patient factors. Operational factors: Beginners do not have a deep understanding of the different levels of acupuncture in the intervertebral ligament, so it is inevitable that puncture will occur; when puncturing the needle is too fast, sometimes mistakes are inevitable; the bevel of the puncture needle is too long, and the quality of the catheter is excellent. Increases the likelihood of perforating the dura. Patient factors: due to repeated trauma, bleeding or chemical stimulation of drugs, the epidural space is narrowed due to adhesion, and the puncture needle can often penetrate the dura after passing through the ligamentum flavum; spinal deformity or disease, huge intra-abdominal mass Or ascites, the spine is not easy to bend, causing difficulty in puncture; repeated exploratory puncture may penetrate the dura mater; in the elderly, the ligament is calcified, and the force during puncture is too large, often slipping into the subarachnoid space after passing through the ligamentum flavum, so the elderly The perforation rate is 2 times higher in humans than in young adults; in children, because the epidural space is narrower than in adults, the operation is more difficult and the dura is more likely to be perforated.

2. Prevention must be carried out in accordance with regular operating procedures every time; do not rely too much on various epidural indicating devices; operator knowledge and experience are more important for determining the entry of the puncture needle into the epidural space; be proficient in puncturing of various approaches Methods: In case of difficulties, the needle insertion method can be changed at will to achieve smooth success; skilled and calm, not blindly pursuing speed, the most important thing is the first test volume to avoid mistakenly entering the subarachnoid space.

3. Treatment after perforation Once the dura is perforated, it is best to change to other methods, such as nerve blocks. If the puncture point is below L2, and the surgical area is in the lower abdomen, lower limbs or anus and perineum, spinal anesthesia can be prudently performed.

2. The puncture needle or catheter is mistakenly inserted into the blood vessel

The epidural space is rich in blood vessels, and it is not uncommon for puncture needles or catheters to stray into the blood vessels, especially in full-term pregnancy.

The measures to prevent the puncture needle or catheter from piercing the blood vessel include: the catheter should be inserted from the dorsal midline approach; the front end of the catheter should not be too sharp; after the catheter is placed in place, it should be gently aspirated before injecting local anesthetic to verify whether there is blood; routine Inject the test dose of local anesthetic first through the catheter; if there is blood in the catheter and the syringe containing the local anesthetic, be alert to the possibility of the catheter entering the vein

3. Air embolism

Epidural puncture is performed, and the gas injection test is used to determine whether the puncture needle has entered the epidural space, which is a common identification method and also provides a way for air to enter the circulation.

Due to the lack of specific clinical manifestations of air embolism, definitive diagnosis of even larger air embolisms is difficult. Usually in the event of air embolism, the patient presents with a sharp drop in end-expiratory CO2 partial pressure and blood pressure, ventricular ectopic, and changes in heart sounds, such as wheezing dyspnea if the patient is conscious. Once a venous air embolism is diagnosed, the patient should be placed in the left lateral decubitus position immediately, which can not only prevent the air embolism from ascending into the brain, but also make the air embolism stay in the right atrium and be broken by the heartbeat to avoid the formation of air mass obstruction. For patients with atrial septal defect or ventricular septal defect, the patient should be placed in the left lateral position, so that the left and right coronary openings are in the lowest position to prevent coronary air embolism; for cardiac arrest, such as chest compression for 2 to 3 If min is invalid, chest compressions and ventricular puncture should be performed immediately.

4. Perforation of the pleura

The puncture needle is deviated to one side and the needle is inserted too deep, which may puncture the pleura, resulting in pneumothorax or mediastinal emphysema.

Fifth, the catheter is broken

1. Reasons Catheters that have entered the epidural space can often be cut off by the bevel of a sharp puncture needle; the catheter is easy to become hard and brittle after poor texture or repeated use; when it is difficult to extubate, the catheter will be pulled off if it is pulled out forcefully.

2. Treatment Because the catheter stump left in the epidural space is not easy to locate, even if the tube is made of X-ray opaque material, it is difficult to distinguish it from the bone on the X-ray film, and the residual catheter generally does not cause complications. It is best to explain to the patient's family members to reassure the family members, so as to avoid unnecessary worries for the patient, and at the same time, they should continue to observe. If the broken tube is found after the operation, and the broken end of the catheter is subcutaneous, it can be taken out through the incision under local anesthesia.

6. General spinal anesthesia

The puncture needle or epidural catheter is mistakenly inserted into the subarachnoid space and cannot be detected in time. Local anesthetics that exceed the amount of spinal anesthesia several times are injected into the subarachnoid space, which can produce an abnormally extensive block, which is called general spinal anesthesia. The clinical manifestations were analgesia, hypotension, loss of consciousness, and respiratory arrest in all areas innervated by the spinal nerves. The symptoms and signs of general spinal anesthesia mostly appear within a few minutes after injection, and cardiac arrest may occur if not treated in time.

1. Prevention To prevent the perforation of the dura mater, it is emphasized that the test dose should be injected before the injection of the full amount of local anesthetic.

2. Treatment Maintain the patient's circulatory and respiratory function. If the patient stops breathing and loses consciousness, endotracheal intubation, mechanical ventilation, accelerated infusion, and if necessary, intravenous infusion of vasoconstrictors to increase blood pressure should be performed. If the circulatory function can be maintained stable, the patient can be awake after 30 minutes and resume spontaneous breathing.

7. Abnormally extensive block

After injection of conventional doses of local anesthetics, abnormally extensive nerve block occurs, but it is not general spinal anesthesia. Although the block is wide, it is still segmental, and the phenomenon of respiratory and circulatory inhibition needs to be dealt with.

8. Spinal nerve root injury and spinal cord puncture

Spinal cord puncture injuries, due to secondary edema, make the clinical presentation much more severe than the actual injury. Treatment measures include dehydration therapy, which can reduce the compression of edema on blood vessels in the spinal cord and reduce neuronal damage; corticosteroids can prevent lysosome damage and reduce autolysis after spinal cord injury, and should be applied as soon as possible.

The consequences of spinal cord injury are serious, and prevention should be the main priority. Puncture above L2 should be especially careful. If there is abnormal sensation or pain during puncture, the needle should be withdrawn for observation.

9. Epidural hematoma

The direct cause of the formation of hematoma is the injury of the puncture needle, especially the inserted catheter, and factors that promote bleeding, such as the patient's coagulation mechanism disorder and anticoagulation therapy.

1. Prognosis depends on early diagnosis. The effect of surgical removal of hematoma within 8 hours is better. Delayed surgery often leads to permanent disability. Therefore, seeking the opportunity to decompress the hematoma as soon as possible is the key to treatment.

2. Prevention Epidural anesthesia should be avoided for patients with coagulation disorders and anticoagulant therapy; for general patients, epidural puncture and catheter placement should be careful and gentle. The dosage is 5 ml each time, and other anesthesia methods are used after the blood color of the reflux fluid becomes pale.

10. Infection

Epidural and subarachnoid infections are the most serious complications.

1. Staphylococcus is the most common pathogenic bacteria in epidural space infection. The bacterial invasion routes include: contaminated anesthetic appliances or local anesthetics; puncture needles pass through infected tissues; acute or subacute infection foci in other parts of the body, bacteria spread through blood Infection of the epidural space.

2. In subarachnoid space infection, symptoms of meningitis usually appear about 4 hours after epidural block, that is, chills, headache, fever and neck stiffness; cerebrospinal fluid is cloudy, leukocytosis, and bacteria are often difficult to detect on smears. Bacterial type of infection, antibiotics are given.

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