Epidural anesthesia during childbirth

The technique of catheterization of the epidural space is described in many manuals; the most popular epidural anesthesia during childbirth is the technique of loss of resistance. Lidocaine and bupivacaine may be used. Comparative studies of the use of various AI in labor did not reveal any differences in the evaluation of newborns on the Apgar scale, indices of CBS, and neuropsychiatric status. It should be noted that the use of bupivacaine in a concentration of 0.25-0.5% can cause a high degree of motor block, which is accompanied by an increase in the frequency of imposition of obstetric forceps by a factor of 5 and posterior occipital presentation by a factor of three. Currently, 0.125% of bupivacaine is considered the drug of choice for epidural anesthesia during childbirth, because at this concentration it does not adversely affect the dynamics of the birth act. The use of MA in low concentrations may lead to inadequate analgesia (more often in sympathetics). The combination of MA with the central alpha-agonist (clonidine) improves the quality of analgesia, helps to reduce the dose and the frequency of side effects.

[1], [2], [3], [4], [5], [6], [7], [8], [9], [10]

Epidural anesthesia during labor in the first period

If epidural anesthesia is performed during childbirth in the first period, it is necessary to carry out a sensory blockade at T10-L1 level. Puncture and catheterization of the epidural space for the anesthesia of labor is performed at the L3 level.

The duration of normal delivery is 12-14 h in primipara and 7-8 h in maternity females. To the category of pathological births include labor lasting more than 18 hours. Fast delivery is considered to be from 4 to 6 hours in primiparas and 2-4 hours in mongrel. Rapid births last 4 hours or less in primiparas and 2 hours or less in maternity females

I period of childbirth (opening period) lasts 8-12 hours in primiparous and 5-8 hours in moles, begins with the appearance of regular bouts and ends with the full opening of the cervix. The slow opening phase of the cervix is characterized by progressive smoothing and slow opening by 2-4 cm. The rapid opening phase is characterized by frequent contractions (every 3-5 minutes) and rapid opening of the cervix to 10 cm. The second period (the period of expulsion) continues from the moment of complete opening cervix of the uterus before the birth of a child - 1-2 hours in primiparas - from 5 minutes to 1 hour in maternity females II period is divided into 2 phases. 1-st phase - from the full opening of the cervix until the insertion of the head; The second phase is from the insertion of the fetal head to its birth.

III period (postpartum) begins with the birth of the child and ends with the separation of the placenta and membranes from the walls of the uterus and their birth.

Pain in the first stage of labor is due to contractions and opening of the cervix. Nerve fibers that transmit these painful sensations enter the spinal cord at the Th10-Th12 level. Visceral afferents, which conduct pain when the child enters the active phase, within the sympathetic nerves reach the plexus of the uterus and its cervix, and then pass through the hypogastric and aortic plexus into the spinal cord as part of the Th10-L1 rootlets. The appearance of pain in the perineum indicates the beginning of the fetal expulsion and the onset of the second stage of labor. Stretching and squeezing the anatomical structures of the pelvis and the perineum increases pain. Sensitive innervation of the perineum is performed by the genital nerve (S2-S4), so pain in the 2nd period encompasses Th10-S4 dermatomes.

MA can be introduced into the epidural space only with the established active labor activity!

Epidural anesthesia during childbirth begins at the opening of the cervix for 5-6 cm in primiparas and 4-5 cm in the re-emergent after the infusion preload, including 500-1000 ml of solutions that do not contain dextrose, and the administration of a test dose (1% lidocaine or 0 , 25% bupivacaine 7 3-4 ml) MA to exclude subarachnoid or intravascular catheter placement.

Preload: Sodium chloride, 0.9% rr, iv I 500-1000 ml, once.

Test dose: Bupivacaine, 0.25% rr, epidural 3-4 ml, single or lidocaine, 1% rr, epidural 3-4 ml, once ± Epinephrine epidurally 15-20 mkg, once (according to indications).

In / in the introduction of drugs can cause dizziness, metallic taste in the mouth, ringing in the ears, tingling around the mouth area. In pregnant women, the method of administering a test dose does not always prevent the introduction of an anesthetic into the lumen of the vessel. If the injection of MA with epinephrine (15-20 mcg) for 30-60 sec causes a heart rate increase of 20-30 / min in the parturient who does not receive beta adrenoblockers, the catheter (needle) is in the lumen of the vessel. The diagnostic value of this test is not absolute; The heart rate can fluctuate significantly during fights. In the literature, the development of a bradycardia after intravenous injection of 15 μg of epinephrine is described. In addition, it is proved that this dose of epinephrine reduces uterine blood flow (the degree of decrease, apparently, depends on the level of the initial sympathicotonia) and causes distress in the fetus / newborn. In this connection, MA solutions containing epinephrine are often used only as a test dose.

Subarachnoidal administration of anesthetic is accompanied by a heat surge, numbness of the skin and weakness in the muscles of the lower extremities.

Monitoring of vital functions is carried out every minute in the first 5 minutes, then every 5 minutes for 20 minutes and, finally, every 15 minutes. The first dose of anesthetic is slowly, fractional, 2-3 ml at intervals of 30-60 s until the calculated dose: Bupivacaine, 0.25% rr, epidurally 10-12 ml, single or lidocaine, 1% p- p, epidurally 10-12 ml, once ± I Clonidine epidurally 50-150 mcg, according to indications (more often fractional). Continue EA according to one of the schemes: in the case of the appearance of pain before the beginning of the II period, MA is injected repeatedly (10-12 ml); conduct a permanent epidural infusion with the introduction of the initial volume of anesthetic per hour, but at half the concentration (the rate of administration is adjusted depending on the effectiveness of epidural anesthesia during labor).

With the combination of MA with clonidine analgesic effect occurs after 15 minutes and lasts about 3-5 hours.

Indications for epidural anesthesia:

• with ineffectiveness of other methods of anesthesia;
• women with gestosis and severe hypertension;
• pregnant women with extragenital pathology;
• women with DRD;
• pregnant women with multiple pregnancies and pelvic fetal presentation;
• when delivering by applying obstetric forceps.

Benefits of epidural anesthesia:

The technique is effective, predictable, rarely complicates; and the patient is able to cooperate with medical staff; o Continuous infusion of anesthetic through the catheter maintains the comfortable state of the parturient woman throughout the delivery; and if necessary caesarean section provides an adequate level of protection.

Advantages of permanent infusion:

• more constant level of analgesia;
• less common dose of local anesthetic;
• less risk of developing a toxic reaction to it.

Disadvantages of permanent infusion:

• additional costs for infusion pumps;
• the need for breeding MA;
• the risk of inadvertent removal of the catheter from the epidural space and the infusion of anesthetic not for the intended purpose.

Relative contraindications to epidural anesthesia:

• refusal of the patient from this type of anesthesia,
• anatomical and technical difficulties for performing manipulation;
• neurological diseases.

Absolute contraindications to epidural anesthesia:

• lack of qualified anesthetic staff and monitoring equipment;
• the presence of infection in the area of the proposed puncture;
• treatment with anticoagulants or bleeding disorders;
• hypovolemia (blood pressure <90/60 mm Hg), anemia (hemoglobin <90 g / l), prenatal bleeding;
• tumor at the site of the proposed puncture;
• three-dimensional intracranial processes;
• pronounced spinal anomalies.

[11], [12], [13], [14]

Epidural anesthesia during labor in the second period

In the II period, epidural anesthesia during childbirth should be extended to S2-L5 dermatomes. If the epidural catheter is not installed in the first stage of labor, the puncture and catheterization of the epidural space in the sitting position is performed. If the catheter was installed, the woman in labor is transferred to the sitting position before the injection of the anesthetic. If necessary, an infusion load is performed and a test dose of MA (3-4 ml) is administered.

If after 5 minutes there are no signs of anesthetic entering the blood or subarachnoid space, 10-15 ml of LS are injected at a rate of no more than 5 ml in 30 seconds:

Bupivacaine, 0.25% rr, epidurally 10-15 ml, single or lidocaine, 1% rr, epidurally 10-15 ml, once.

The parturient is transferred to the prone position with a roller under the right or left buttock, measure BP every 2 minutes for 15 minutes, then every 5 minutes.

It should be remembered that epidural anesthesia during childbirth is an invasive procedure and not without undesirable side effects and complications. An important component of safety is awareness of possible complications of epidural anesthesia of all team members (anesthesiologist, obstetrician and neonatologist) and their ability to prevent or timely eliminate these complications. The parturient is at the center of this process: she is the only one who gives informed consent to perform the manipulation, in connection with which the anesthesiologist and obstetrician (jointly) are obliged to provide her with objective information about the risk. Since in any postpartum problems it is easy to blame epidural anesthesia, it is necessary to inform all those involved in the process (doctors and the woman in childbirth) of real risks and problems, only in time coinciding with it.

Taking a pregnant small doses of acetylsalicylic acid is not a contraindication for epidural anesthesia. Prophylactic use of heparin is stopped 6 hours before EA, but the prothrombin time and APTT should be normal. When the number of platelets is more than 100 x 103 / ml, conducting epidural anesthesia is safe without performing coagulation tests. When the platelet count is 100 x 103 - 50 x 103 / ml, the hemostasiogram must be checked for the presence of the DIC syndrome, in case of normal results of epidural anesthesia it is not contraindicated. With an amount of platelets of 50 x 103 / ml, epidural anesthesia is contraindicated. In addition, epidural anesthesia is not indicated in the presence of scars on the uterus, pronounced narrowing of the pelvis, giant fruit (more than 5000 g). Premature separation of amniotic fluid is not a contraindication for epidural anesthesia if there is no suspicion of infection.

Births through natural birth canals after cesarean section in the lower uterine segment are not currently contraindicated to RA. The opinion that RA can mask the pain caused by rupture of the uterus along the scar is recognized as insolvent, because such a break often occurs painlessly even in the absence of anesthesia. The most reliable symptom of uterine rupture is not pain, but changes in the tone and nature of uterine contractions.

[15], [16], [17], [18], [19]

Problems of epidural anesthesia in childbirth

• difficulty (impossibility) of catheterization of the epidural space occurs in 10% of cases;
• The vein puncture occurs in about 3% of cases. A random intravascular injection of MA can lead to dangerous complications, including convulsions and cardiac arrest. With the possible exception of Doppler echocardiography, all methods of identifying the vascular puncture (see above) often give false-positive or false-negative results. The use of low-concentration MA and a slow rate of administration increase the likelihood of detecting intravascular administration before the catastrophic consequences develop;
• puncture of the dura mater occurs in approximately 1% of cases. About 20% of these complications are not recognized at the time of the manipulation, the danger is a total spinal block; the unintentional entry of a needle or catheter into the lumen of the vessel or the subarachnoid space is possible even if no bleeding or cerebrospinal fluid is obtained in the aspiration sample;
• an incomplete block is received in 1% of cases, it is caused by an insufficient dose of anesthetic, its one-sided spread, subdural catheter introduction, the presence of adhesions in the epidural space;
• repeated manipulations produce approximately 5% of cases. Causes - getting into the vein, catheter displacement, incomplete block, puncture of the dura mater;
• the toxic effect of acute or cumulative overdose of MA is rare if bupivacaine is used. Early signs are dizziness and tingling around the mouth. There have been reports of the development of seizures and circulatory arrest;
• arterial hypotension develops in about 5% of cases, the most likely cause is a vegetative blockade in the background of the ACC syndrome;
• excessive motor block is an undesirable effect of epidural anesthesia in childbirth, its development depends on the dose of anesthetic;
• the development of infection is rare if the rules of asepsis are observed. However, isolated reports of epidural abscesses emphasize the need for postnatal observation:
• retention of urine during labor is possible without epidural anesthesia;
• nausea and vomiting are not the companions of epidural anesthesia;
• back pain, contrary to popular belief, is not a complication of epidural anesthesia;
• the distress of newborns is not a consequence of correctly conducted epidural anesthesia, which improves placental blood flow;
• prolonged labor / increased risk of surgical delivery. Correctly performed epidural anesthesia does not increase the risk of surgical delivery. It is proved that early epidural anesthesia (when the cervix is opened by 3 cm) does not increase the frequency of cesarean section or instrumental delivery;
• Neurological complications are more often caused by obstetric causes. The neurological deficit associated with epidural anesthesia involves compression of the spinal cord with hematoma or abscess (can occur in women in labor without spontaneous and without epidural anesthesia), damage to the spinal cord or nerve with a needle or injected air, neurotoxicity of drugs deliberately or accidentally injected into the epidural space.

A careful evaluation of the woman's condition before and after the epidural anesthesia, careful execution of manipulation are key points in the prevention and timely correct diagnosis of complications. The absence or inadequacy of the informed consent of a pregnant woman to conduct epidural anesthesia during childbirth is a frequent cause of complaints.