Surgical operations during pregnancy: when can’t you wait? Is it possible to administer local anesthesia to pregnant women?

None of us are immune from health problems; often these kinds of troubles also worry expectant mothers. Particularly serious diseases sometimes require urgent surgical intervention, which raises a lot of questions and worries, since treatment, especially anesthesia, is not particularly desirable during pregnancy. But there is no point in delaying the operation if it is urgent and urgent. Here you have, as they say, a double-edged sword.

During pregnancy, the mother's body works in a special mode, the composition of the blood changes, and the load on all organ systems increases. Chronic diseases may worsen and progress to a stage where immediate surgery is required. Also, the help of a surgeon may be needed in case of an unexpected injury or dental problem. Therefore, doctors must be extremely careful not to harm either the mother or the child; their work is comparable only to jewelry.

At what stage of pregnancy is anesthesia safest for the unborn child?

During the operation, responsibility lies not only with the surgeon, but also with the anesthesiologist; he needs to very accurately calculate the dose of anesthesia, taking into account the gestational age, fetal sensitivity, placental permeability, and possible consequences. An incorrectly selected dose of anesthesia during pregnancy can cause disturbances in the development of the child, its metabolism, and in especially severe cases, provoke deformity or death of the baby. A particularly dangerous period for administering anesthesia is considered to be 2-8 weeks inclusive. From the 28th week until the end of the pregnancy, the risk is also increased. If surgical intervention is necessary and there is an opportunity to delay time, then doctors recommend the period from 14 to 28 weeks for operations, during which time the uterus does not react so strongly to external influences, and the baby’s main organs are already formed.

What types of anesthesia are acceptable for pregnant women?

The most suitable method in terms of safety is regional anesthesia. In this case, anesthesia is administered over the membrane of the spinal cord, while the mother remains conscious, the lower part of the body becomes anesthetized. But options cannot be excluded when there are contraindications to this method, for example, neurological diseases, or it cannot be used due to the duration of the operation. Therefore, doctors have to use multicomponent balanced anesthesia, which requires artificial ventilation. Before the operation, medications must be prescribed that help reduce the acidity of gastric juice to prevent vomiting.

The drugs used for anesthesia will depend on your age, condition and complexity of the operation. For minor operations, lidocaine is usually used, which provides local anesthesia; it breaks down quite quickly and does not have time to harm the fetus. Ketamine is prescribed for intravenous anesthesia, but it is used in small doses and carefully, since it can increase the tone of the uterus; in the third trimester, its negative effects become more weakened. Nitrous oxide is used for combined anesthesia, but very rarely and for a short time; this drug is harmful to a small organism. If the expectant mother suffers from severe pain, then Morphine or Promedol can be used for injections; they are the least dangerous and almost do not cause developmental defects in the child. Of course, you must be extremely careful and prevent such health situations from arising. If the inevitable happens, then you should trust only experienced and qualified specialists.

Medical statistics show that 2% of pregnant women need to perform some kind of surgical intervention related to acute diseases, injuries or the need for dental treatment. In some cases, anesthesia is used to eliminate pain, in others local anesthesia is used, the choice is made individually in each specific case.

When is anesthesia used during pregnancy?

Unfortunately, the happy state of expecting a baby in some pregnant women is overshadowed by the development of acute diseases that require urgent surgery and, of course, pain relief. It is well known that any operation and anesthesia contain a certain amount of risk for an ordinary patient. During pregnancy, this risk increases - both for the fetus and for the woman herself.

And yet, despite all the risks, the doctor is obliged to choose the lesser of two evils, because in any case, anesthesia during pregnancy is associated with operations that are performed for health reasons in the following cases:

• acute appendicitis;
• acute cholecystitis;
• peritonitis;
• intestinal obstruction;
• bleeding of various etiologies;
• acute gynecological pathology (ovarian cyst torsion);
• injuries of the abdominal and thoracic cavities;
• development of abscesses, phlegmon, purulent pleurisy.

Sometimes general anesthesia can be used for various manipulations and diagnostic procedures. For example, in the case of esophagogastric bleeding, it is carried out.

It is extremely rare to use anesthesia in dental practice. In the vast majority of cases in pregnant women, it is performed using local technology.

Advice: If pain or injury occurs, pregnant women should not take any analgesics, sedatives, or hypnotics on their own without the knowledge of the doctor. They can “erase” the manifestations of the disease and also have a negative impact on the fetus. In these cases, you should immediately consult a doctor.

How does anesthesia affect the mother and fetus?

It is quite true that there are no harmless medicines, or, as they say in everyday life, one medicine heals, and another cripples. This is quite true in relation to anesthesia. General anesthesia affects the nervous, vascular, respiratory and endocrine systems, metabolism, liver and kidney function.

But the question is that such anesthesia is nothing more than a vital necessity, and it is performed in pregnant women only during operations that have vital indications. Here, as they say, there is nowhere to go, and the choice is clear. In principle, modern technologies prevent any serious and long-term damage, and it is quickly cleared and restored.

As for the unborn child in the womb, anesthesia poses a much greater danger for him, especially in the early stages. Any negative effects in the first trimester, including narcotic drugs, sedatives, analgesics, can affect the formation of fetal organs and subsequently various congenital anomalies can form.

At later stages of pregnancy, that is, after 3 months, the fetus is already fully formed, that is, it is already a real little person with the functioning of all organs and systems. At these times there is no need to worry about anomalies, but the consequences may manifest themselves in the form of hypoxia and developmental delays.

Advice: Once a situation has arisen where an operation under anesthesia is necessary on a pregnant woman, we must overcome all fears and realize that this choice is being made in the name of preserving life, and the possible consequences of anesthesia in this case are secondary. Moreover, modern anesthesia technologies are more gentle, and it is possible to eliminate negative consequences.

How to choose anesthesia during pregnancy

The basic principle of pain management during pregnancy is to make maximum use of local anesthesia. The best option for both the mother and her unborn baby is epidural anesthesia - the injection of an anesthetic around the dura mater of the spinal cord. This method does not cause significant general intoxication, but only temporary side effects occur in the form of nausea, changes in blood pressure, and so on.

When there is a question about serious abdominal interventions, when muscle relaxation is necessary, anesthesia is used. There are many types of it - mask, intravenous, intubation. Various narcotic substances are used - nitrous oxide, fluorotane, calypsol. For pregnant women, anesthesia is selected individually - neuroleptanalgesia with drugs that do not affect the tone of the uterus and do not interfere with the blood circulation of the placenta.

An example of such a drug is calypsol, which is used for short-term intravenous anesthesia and is subsequently quickly eliminated from the body. In any case, the choice of anesthetics and their combination are selected individually, depending on the nature and duration of the upcoming operation.

In dentistry, when urgent dental treatment is necessary in pregnant women, anesthesia is used extremely rarely; local anesthetics are used - lidocaine, ultracaine and others.

Anesthesia during pregnancy is dictated by necessity - life-saving interventions. If performed professionally by specialists, it does not have dangerous consequences for the body.

Attention! The information on the site is presented by specialists, but is for informational purposes only and cannot be used for independent treatment. Be sure to consult your doctor!

There is no doubt: the treatment of pregnant women requires special attention and careful selection of medications. This is true for surgery and (doubly!) for anesthesiology. There are no absolutely safe anesthetic drugs; they all have their own toxicity threshold, which they reach in certain doses. And in each specific case, the anesthesiologist needs to correctly calculate the dose in order to put the patient to sleep, make him insensitive to pain, completely relax all the muscles and even stop his breathing. But all this is only for the duration of the operation itself, after which the person must “wake up”.

Any surgical intervention and associated anesthesia carries a certain risk for any patient. What can we say about a woman carrying a child under her heart! Pregnancy significantly changes the functioning of almost all major organs and systems of a woman. She begins to breathe differently, her liver, kidneys and heart work harder, the composition of her blood changes, her immune system is partially suppressed, her digestive organs are forced to work in a “squeezed” state, etc. And all this changes as the pregnancy itself progresses. When choosing anesthesia, the doctor takes into account the permeability of the placenta for anesthetic drugs, the baby’s ability to “digest” anesthetic “cocktails” and their effect on the formation of a small organism. All this puts a pregnant woman in a special risk group.

Most often, a pregnant woman ends up on the surgical table due to injuries, acute surgical diseases of the abdominal organs (such as appendicitis), exacerbation of chronic surgical diseases and dental problems.

So, in the first and second trimesters, anesthetic drugs are more dangerous for the child than for the mother, especially in the period between. At this time, the formation of the baby’s main organs occurs, and most anesthetics (painkillers) pass through the placenta, inhibiting the growth and development of cells, thereby increasing the risk of deformities (terratogenic effect). In addition to this, due to the operation itself and the action of anesthetic drugs, placental and uterine blood flow is disrupted, and the child’s nutrition deteriorates.

Surgery is also important for the mother. Due to the release of adrenaline and other stress factors, the risk of miscarriage increases. The mother is more likely to vomit during surgery and have the vomit enter the lungs (aspiration) and develop severe pneumonia. Because of all these dangers, in the first and second trimesters, pregnant women are operated on under general anesthesia only for health reasons, that is, in cases where refusal to operate directly threatens the life of the mother. Minor surgeries can be performed under local anesthesia, where an anesthetic is injected directly into the site of the planned surgery (for example, emergency dental procedures). But even so, part of the anesthetic can reach the baby, and maternal pain can increase the tone of the uterus, worsen uteroplacental blood flow and increase the risk.

If necessary and if possible, doctors try to reschedule the operation to a later date (second trimester), since at this time the child’s organs are formed, and the excitability of the uterus to external influences is minimal.

In the third trimester, the risk of miscarriage and life-threatening complications increases even more; the abdominal organs are displaced and “squeezed” by the uterus, which also puts pressure on the main blood vessels in the abdomen, disrupting blood flow. Increased pressure in the abdominal cavity is transferred to the chest cavity, reducing the volume of respiratory movements, and the need for oxygen, on the contrary, increases: the mother also breathes for the child. Therefore, if major surgical interventions are necessary, doctors try to wait until the child’s lungs mature. First, they perform it in the usual manner, and then perform the necessary operation.

Pain relief for expectant mothers - the best choice

The safest method of pain relief for mother and baby during pregnancy is considered epidural anesthesia.

To carry it out, a needle is inserted through holes in the spinal canal directly above the dura mater of the spinal cord, into the epidural space - just where the nerve roots pass that carry pain impulses from the uterus. To make the procedure painless, the skin at the site of the intended injection is numbed before the injection. Then a special needle is inserted into which a thin silicone tube (catheter) is inserted; the needle is removed, and the catheter remains in the epidural space - a strong local anesthetic is injected into it. As needed, a medicinal substance can be added through the catheter, prolonging the analgesic effect to 24-36 hours.

What to do if you are injured or have a question about emergency surgery?

In any situation, do not forget to tell the doctors that you are pregnant, indicate the due date and indicate whether you have a burdened obstetric history (complications during preparation for pregnancy or complications from this and previous pregnancies). Your escorts should know this too.

If you are offered hospitalization, do not refuse, just ask to be taken to a multidisciplinary hospital, where, in addition to a specialist in your illness, there will also be obstetricians and gynecologists.

Don’t be afraid if, in case of severe pain, the ambulance doctors give you an injection of Morphine or Promedol: these narcotic analgesics have been studied very well, and it has been proven that they do not harm the baby, and you will reduce the risk of miscarriage due to adrenaline and its derivatives, which accumulate in the body from pain and increase the excitability of the uterus. Both mother and child do not become accustomed to narcotic analgesics in such a short period.

Tell the anesthesiologist everything about your chronic diseases and your pregnancy, including the presence of intolerance not only to medications, but also to foods and odors, because he will have to choose the method of anesthesia during surgery.

What to expect during surgery

Immediately before surgery, Ranitidine is prescribed once or twice to reduce the acidity of gastric juice and reduce the risk of gastric burn to the upper respiratory tract in case of unexpected vomiting during anesthesia. In this dosage, it usually does not affect the development of the child’s nervous system.

If possible, pregnant women undergo regional (epidural, conduction) anesthesia. And if it is impossible to use this method, multicomponent balanced anesthesia with artificial ventilation of the lungs is performed through a special tube inserted into the trachea (endotracheal tube).

Mask anesthesia, in which the anesthetic enters the body through the respiratory tract, is not given to pregnant women due to the high risk of vomiting and getting it into the respiratory tract (aspiration).

Nitrous oxide, used inhalation - using a mask, with constant use can cause miscarriage or harm the development of the child. However, in low concentrations (ratio to oxygen content 1:1) and for a short time, it is still prescribed during surgery. In this mode, it does not have time to have a negative effect, but causes good sleep and relaxes the muscles, including the uterus.

Ketamine (Calipsol)- an anesthetic, which is usually used for intravenous anesthesia, is used in the first and second trimester in small doses only for special indications and in combination with other drugs, as it increases the tone of the uterus. In the third trimester, its negative effect decreases.

When working with pregnant women, the anesthesiologist chooses pain management tactics and anesthesia drugs that meet the following principles:

• maximum child protection,
• support of normal placental blood flow,
• decreased excitability and decrease,
• supporting the sustainable functioning of the mother’s body in the face of changes associated with pregnancy.

In any case, if the need for surgical intervention arises, the doctor chooses one or another method of pain relief depending on the patient’s condition, the duration and characteristics of the proposed surgical intervention, and the capabilities of the given anesthesiology department, so it is impossible to clearly name the optimal method for such cases.

If surgery is necessary, you must follow all the recommendations of the anesthesiologist and other doctors and take the medications that are prescribed to you. If you doubt them, discuss it again with your doctor. Remember that almost all medications say that it is not recommended to take them during pregnancy. But when the issue of your health and life, as well as the health and life of the baby, is being decided, taking some medications is possible - of course, only under the control and supervision of your doctor.

The main thing is caution!

Thus, surgical treatment methods and their anesthesia for a pregnant woman are complex and dangerous, but sometimes they cannot be avoided. There is only one way out in this situation: take care of yourself! Try to deal with your chronic diseases that require surgery before pregnancy. Don’t forget about dental problems: sadly, one of the reasons for abortions is dental intervention during pregnancy, especially acute conditions, that is, dental diseases that cause toothache. Their treatment, as a rule, is also associated with pain. However, most of these diseases can be prevented by treatment before testing.

Try to avoid places that are dangerous for injury. If you are busy in production, ask management to comply with the Labor Code and transfer to a quiet area. Please note that a car is not the safest place in the city, and even if an ace is driving your car, it is possible that your neighbor on the highway will be a reckless driver. During pregnancy, you should sacrifice panache for convenience: hide thin stilettos, high heels and slippery soles away in the closet. Wear comfortable and stable shoes. Reduce for yourself and for your unborn child the risk of injury in the apartment (sharp corners, boxes falling from mezzanines, swinging stepladders and stools, etc.).

But if the need for surgical intervention does arise, do not delay, consult a doctor. Take care of yourself and your baby.

Dmitry Ivanchin
anesthesiologist-resuscitator,
senior doctor of the operational department of the Emergency Care Center of the Moscow Department of Health

Charles P. Gibbs, M.D.
Professor and Chairman

Joy L. Hawkins, M.D.
Associate Professor
University of Colorado Health Sciences Center
Denver, Colorado 80262

Surgery during pregnancy is not that uncommon. Every year, 0.75-2 percent of pregnant women undergo surgery. In the United States, approximately 75,000 anesthesia procedures are performed annually for this reason 1,2. The most common reasons for surgery are trauma, ovarian cyst, appendicitis 3,4, breast tumors and cervical pathology. We also point out that pregnant patients have successfully undergone craniotomy under controlled hypotension, heart surgery with cardiopulmonary bypass, and even liver transplantation. During all these manipulations, we take care of the safety of both the mother and the fetus. In this regard, it is necessary to remember the following things: 1) some physiological processes in the body of a pregnant woman occur differently; 2) certain anesthetics appear to be teratogenic; 3) during anesthesia, the blood supply to the uterus should in no case be disrupted; 4) anesthesia may adversely affect the fetus; and 5) premature birth is unacceptable, since it is the main cause of death of the child.

Physiological changes during pregnancy

When planning anesthetic care for a pregnant woman, drawing up an anesthesia plan, the anesthesiologist must take into account the physiology of the mother and fetus. Already in the first trimester, there is an increase in cardiac output and circulating blood volume, and by 28 weeks of gestation these indicators are already 30-40 percent higher than those before pregnancy. If a woman is pregnant with twins, her circulating blood volume may increase by 60 percent. By about 30 weeks of gestation, cardiac output increases by 30 percent. This indicator reaches its maximum value immediately after childbirth (increases by 80 percent of the norm), which is associated with autotransfusion of blood from the reduced size of the uterus and the cessation of compression of the abdominal aorta and inferior vena cava; Usually cardiac output returns to its original parameters by 12 weeks postpartum, although this may not occur. Normal blood pressure is maintained by vasodilation. Despite an increase in circulating blood volume and cardiac output, pregnant patients are prone to hypotension in the supine position. Approximately 10 percent of women in late pregnancy may experience symptoms of hypovolemic shock when lying on their back, which occurs due to mechanical compression of the inferior vena cava, which impairs venous return to the heart. Compression of the abdominal aorta does not cause any significant symptoms in the mother, but causes hypotension in the uterine vessels and fetal hypoxia. Therefore, during transportation to the hospital and throughout the entire stay in the operating room, it is necessary to shift the uterus to the left side.

The most significant change in pulmonary function during pregnancy is a decrease in functional residual capacity (FRC). Starting from the second trimester, FRC decreases by 20 percent, while oxygen consumption increases by 20 percent. In addition, 30 percent of pregnant women, especially smokers and late-parous women, experience airway closure during normal exhalation when lying on their back. These factors reduce the delivery of oxygen to the body at a time when it is needed in increased quantities, which predisposes to a rapid drop in p02 in the operating room during apnea or a short episode of airway obstruction. All pregnant patients should receive adequate preoxygenation before intubation. The minute volume of ventilation in pregnant women is increased by 50 percent due to an increase in tidal volume; therefore, the normal value of pco2 decreases by 10 mm. Hg Art., which is accompanied by a decrease in bicarbonate concentration. Arterial pO2 values ​​are elevated as alveolar ventilation increases by 70 percent. Throughout the respiratory tract, capillaries are filled with blood, which increases the likelihood of traumatic injury to the airways during manipulations to maintain their patency or during insertion of a tube into the stomach. It is recommended to use smaller endotracheal tubes (6 or 7), avoid nasotracheal intubation, and avoid inserting gastric tubes through the nose.

Pregnant women have an increased risk of aspiration due to both hormonal and mechanical causes. Gastrin levels begin to increase already in the very early stages of pregnancy, which leads to an increase in the acidity of gastric contents, while progesterone reduces the motor activity of the gastrointestinal tract. An enlarged uterus displaces the pyloric section of the stomach, which disrupts the process of emptying it and leads to dysfunction of the pyloric sphincter. The symptom of “burning pain in the heart” indicates the presence of reflux, which occurs due to a decrease in the pressure gradient on opposite sides of the pyloric sphincter; it averages about 7 mm H 2 O ( for comparison, normally the pressure gradient is 28 mm H 2 O). In the preoperative period, all pregnant patients should be prevented from aspiration using nonspecific antacids, as well as H2 blockers and metoclopramide (Cerucal).

Neurological changes that occur during pregnancy become a factor due to which the minimum alveolar concentration (MAC) of inhalational anesthetics decreases by 25-40 percent. Loss of consciousness can occur even when inhaling “sedative doses” of inhaled drugs. In addition, the need for local anesthetics when administered epidurally and subarachnoidally is reduced by 30 percent, probably due to the effect of progesterone on the sensitivity of the nerve fiber. In the epidural space, local anesthetics spread more widely, which becomes noticeable already in the first trimester of pregnancy, and this phenomenon is caused more by hormonal factors than by mechanical factors (mechanical factors include, for example, dilation of the veins of the epidural space due to compression of the inferior vena cava) .

Oxygenation of the fetus depends on the amount of oxygen in the mother's blood and is directly proportional to the intensity of uterine blood flow. Hyperventilation and alkalosis lead to a shift in the dissociation curve of maternal oxyhemoglobin to the left, which causes an increase in the affinity of hemoglobin for oxygen in the mother's blood, so the fetus begins to receive less oxygen. With continuous positive pressure ventilation, there is a decrease in venous return to the heart, which can cause a 25% reduction in uterine blood flow. Any episode of maternal hypotension, regardless of its cause, can cause fetal asphyxia.

Teratogenicity and safety of anesthesia drugs

What should an anesthesiologist tell a pregnant patient before surgery about the side effects of anesthesia drugs on the fetus? Can an anesthesiologist convince his patient? Serious birth deformities occur at a rate of 3 percent in the general population, but the exact cause or mechanism of a particular deformity can be identified in less than 50 percent of cases 5 . Although anesthesiologists are often asked the question about the teratogenicity of the drugs they use, there is often no consensus and it is sometimes impossible to achieve it. However, the problem of teratogenicity is based on several overarching principles, familiarity with which helps determine the anesthesia plan.

The potential teratogenicity of a drug is influenced by factors such as: 1) timing of drug administration, 2) individual patient sensitivity to the drug, 3) number of drug administrations, and 4) overall incidence of congenital anomalies with the drug. When prescribing teratogenic agents, it is necessary to remember that the fetus is most vulnerable in the 15-90 days of gestation, when the processes of organogenesis occur (Figure 1). The processes of organogenesis are completely completed by the 13th week of gestation; after this time, the main teratogenic effect is expressed in delayed fetal development or the occurrence of functional disorders; gross anatomical defects are less common. Different organs are vulnerable at different times.

The periods of maximum sensitivity of organs to the effects of teratogenic drugs during the period of organogenesis are as follows: for the brain this is 18-38 days of gestation; for the heart - 18-40 days; for visual organs - 24-40 days; for limbs - 24-36 days; for the genitals - 37-50 days.

Drugs can cause specific defects if they are prescribed during the above critical periods of organogenesis, but during other periods of gestation they may not have any pathological effect. Different genotypes show different sensitivity to the effects of teratogenic factors. Children of chronic alcoholics are born with multiple manifestations of fetal alcohol syndrome. 6,7 In addition, there is a certain threshold below which small amounts of the drug are not teratogenic, although higher concentrations may cause congenital anomalies. In any population there is a certain number of congenital deformities, regardless of the effect of certain medications. For example, if 1 million women take acetaminophen (paracetamol) during pregnancy, 30,000 of their children will have other abnormalities that are not related to acetaminophen.

The incidence of developmental anomalies is also influenced by medical and social factors. Congenital anomalies in children born to mothers with diabetes occur in 4-12 percent of cases. Recent studies have found that careful monitoring of glucose levels before implantation of a fertilized egg and throughout pregnancy can reduce the incidence of congenital anomalies to 1.2 percent. 8 Cocaine and heroin abuse lead to microcephaly and other abnormalities of fetal brain development. 9-11 What teratogenic drugs the father took is also of great importance. The offspring of men who abuse cocaine have an increased risk of congenital abnormalities. 12 Cocaine penetrates sperm and can enter the egg during fertilization, causing disruption of normal fetal development. Before any drug, including anesthetics, is classified as teratogenic, it is necessary to carefully assess the possible influence of all the above-mentioned factors.

The study of teratogenicity and abortogenicity of drugs used in anesthesiology occurs in three directions: 1) experiments on small animals ( For example, Sprague-Dawley rats and chick embryos), 2) epidemiological surveillance of operating room personnel and dentists, i.e., individuals who are constantly exposed to subnarcotic doses of inhalational anesthetics, and 3) follow-up studies in women who during pregnancy underwent surgical intervention.

Experiments on small animals

Such studies are difficult to implement in practice and even more difficult to interpret their results. The teratogenic effect is expressed differently in different animal species, and the data obtained during experiments do not always make it possible to predict the possible effects of certain drugs on the human body. For example, thalidomide causes one or two defects in rodents, although the same drug has proven to be highly teratogenic in humans. Experiments in which rodents or chick embryos are placed for long periods of time in an environment with a high concentration of inhalational anesthetics do not accurately simulate the true conditions that exist in the operating room. Researchers may not be able to monitor blood pressure, temperature, ventilation parameters, oxygenation, or blood sugar levels - indicators that are normally closely monitored by anesthesiologists. For example, if sedation or anesthesia prevents a test animal from feeding normally, it may develop hypoglycemia. It is difficult to determine whether physical defects at birth are the result of the drug itself, or whether they arise under the influence of physiological changes induced by the general anesthetic. Despite everything, experiments on small animals are beneficial and must be continued, since otherwise obtaining information about the teratogenicity of drugs would require conducting studies on a large number of pregnant women. Such studies are quite difficult to conduct, and sometimes they are completely impossible.

Experiments on small animals have already established the safety of some drugs. The safety of opioids is beyond doubt. Morphine 13 , fentanyl 14 , sufentanil 15 and alfentanil 15 have been shown to have no side effects even when used in very high doses. Children of women who abuse drugs often exhibit delayed physical development, although in this risk group congenital anomalies at birth are observed with the same frequency as in children born to healthy mothers. 10 Studies have established the safety of other intravenous drugs, such as thiopental, methohexital, etomidate, and ketamine. 16

In 1975, it was first reported that taking diazepam during pregnancy increased the incidence of cleft lip in children. 17 Further studies could not confirm this fact; moreover, it turned out that in addition to diazepam, these women took other teratogenic drugs and abused alcohol. 18 However, the leaflet on the use of benzodiazepines, including midazolam, contains the following warning: “Some studies have found that taking benzodiazepines (diazepam and chlordiazepoxide) during pregnancy increases the risk of congenital anomalies in infants. Therefore, before using drugs from this group during pregnancy, your patient should be advised of the potential for adverse effects of these pharmacological agents on the fetus.” 19 The anesthesiologist must clearly determine whether the use of benzodiazepines is justified in a particular clinical situation.

Studies have found that inhalation of halothane, enflurane or isoflurane during gestation for 6 hours a day for three days at doses of 0.75 MAC (which is 0.8 percent for halothane, 1.05 percent for isoflurane or 1.65 percent for enflurane) does not have a teratogenic effect. 20 The use of lidocaine before conception and throughout the entire period of pregnancy in doses up to 500 mg/kg/day does not have a teratogenic effect and does not affect reproductive functions. 21.22

Nitrous oxide

There is still controversy among anesthesiologists about the appropriateness of using nitrous oxide in early pregnancy, and some scientific centers recommend against its use. 23 Their recommendations are based on the fact that nitrous oxide can inhibit methionine synthetase (MS), which could potentially interfere with DNA synthesis in a rapidly growing fetus. Recent studies in Sprague-Dawley rats have found that a 24-hour inhalation of 75 percent nitrous oxide on day 9 of gestation resulted in a fourfold increase in the incidence of “pregnancy resorption” (which is the equivalent of miscarriages in humans), a sevenfold increase in the incidence of organ abnormalities, and delayed pregnancy loss. formation of the musculoskeletal system. 24 Such a nitrous oxide dosing regimen is extremely rare in non-experimental conditions; in addition, the researchers did not monitor the functioning of the cardiovascular and respiratory systems and carried out inhalation of nitrous oxide during the critical period of gestation. Among other things, the rats did not eat any food during the inhalation of 75 percent nitrous oxide. However, this experiment has brought renewed attention to the issue of the use of nitrous oxide (N2O) during pregnancy in humans. Inhalation of N 2 O causes time- and dose-dependent dysfunction of the bone marrow and megaloblastic anemia, similar to that that develops with vitamin B12 deficiency. This was first described in patients with convulsive syndrome, who were ventilated and sedated using N 2 O. 25-27 Nitrous oxide inactivates vitamin B 12, which is a coenzyme of methionine synthetase (MS), which causes a decrease in the activity of methionine synthetase and disrupts the synthesis of DNA precursors. 28 The administration of folic acid helps prevent dysfunction of the bone marrow, 29 on the basis of which it has been suggested that a decrease in methionine synthetase activity is one of the reasons for the teratogenic effect of nitrous oxide.

Further experiments on Sprague-Dawley rats showed that the activity of MS in the fetus is normally 50 percent of the activity of this enzyme in the mother animal. 30 Inhalation of nitrous oxide resulted in a time- and dose-dependent suppression of metabolic syndrome activity even when the concentration of nitrous oxide was only 7.5 percent. 31 However, the teratogenic effect of nitrous oxide was realized only when its concentration exceeded 25 percent. 32 In other words, inhibition of MS activity was observed at concentrations of nitrous oxide less than 10 percent, while the teratogenic effect of this drug was realized at concentrations of 25 percent or more. Other data also did not support the assumption that the teratogenic effects of nitrous oxide develop due to inhibition of methionine synthetase. Initial experiments were carried out under fairly specific conditions: fetal abnormalities were found with inhalation of 75 percent nitrous oxide for 24 hours, although this dosing regimen is never actually carried out in the operating room. On the other hand, repeated 8-hour inhalations of nitrous oxide during other periods of gestation did not cause any side effects. 35 Such contradictions have forced some researchers to search for other mechanisms through which the side effects of nitrous oxide on the fetus are realized.

Because suppression of MetS activity impairs folic acid metabolism, some researchers have pretreated animals with folic acid (and again given 24-hour inhalation of 75% nitrous oxide on day 9 of gestation). 34 Survival (rate of miscarriages) was similar in the two groups of animals, and the incidence of gross musculoskeletal malformations increased fivefold, from 8.4 percent in the control group to 41.3 percent in the group of animals that received nitrous oxide without folic acid . However, the incidence of abnormalities in the folic acid group was 19.1 percent, which is not much different from the control group. In this regard, some research centers began to prescribe folic acid preparations before surgery to women who are planning to undergo general anesthesia during pregnancy. Recent human studies have shown that administration of folic acid before and after fertilization of the egg leads to a reduction in the incidence of neurological defects in the fetus. 35 For this reason, the United States Public Health Service recommends that all women of childbearing age take folic acid supplements daily.

The data obtained from experiments on rodents is quite difficult to interpret in relation to humans. The two studies below cast doubt on the relevance of the methionine synthetase data in humans. The first study measured MC activity in human placental tissue following cesarean sections performed using nitrous oxide. 36 It was found that in this case, the activity of MC was no different from the level of activity of the same enzyme in the placenta after normal vaginal delivery without the use of nitrous oxide. Since nitrous oxide does not affect MS activity in the human placenta, it is unlikely to inhibit MS in human fetal tissue. A second study measured the rate of MS inactivation in women undergoing laparotomy using 70% nitrous oxide. 37 It turned out that the enzyme activity decreases by half within 46 minutes, but in rats this happens in just 5 minutes. Therefore, it is believed that nitrous oxide has no harmful effects in humans if inhaled for less than 45 minutes.

Disagreements regarding the use of nitrous oxide become significantly less when the problem of biochemical disorders (decreased MS activity) and adverse effects on reproductive processes (miscarriages and congenital anomalies) begin to be considered by specialists each separately. The biochemical theory is based on the assumption that the adverse effects of nitrous oxide on reproductive processes are the result of a decrease in the activity of metabolic syndrome, as a result of which the metabolism of folic acid is disrupted and the processes of DNA synthesis are distorted. However, this does not take into account the fact that disruption of biochemical processes (decreased MS activity) occurs even with inhalation of extremely low doses of nitrous oxide (0.75 percent) for a short period of time (5 minutes), and teratogenic effects are realized within 24 hours. inhalation of nitrous oxide in high concentrations.

There is another theory that considers the effect of nitrous oxide on the tone of the sympathetic nervous system. As is known, nitrous oxide increases the tone of the sympathetic nervous system and causes vasoconstriction. The addition of halogenated general anesthetics to the inhalation mixture of nitrous oxide makes it possible to completely avoid congenital malformations and cases of “resorption of pregnancy,” although the activity of metabolic syndrome in both groups decreases by the same amount. 38,39 The sympatholytic effects of halothane and isoflurane appear to reduce sympathetic hyperactivity caused by nitrous oxide, allowing adequate blood flow through the uterus to be maintained. In this study, the protective effect of folic acid was not confirmed, which gave the right to its developers to declare that there is no need to prescribe folic acid supplements to pregnant women whose general anesthesia is planned to be carried out using nitrous oxide. Researchers argue that teratogenicity is due to the fact that nitrous oxide increases the tone of the sympathetic nervous system and reduces uterine blood flow. A decrease in methionine synthetase activity is unlikely to be the only, much less the main, factor explaining the teratogenic effect of nitrous oxide.

Some retrospective human studies have assessed the effects of nitrous oxide in early pregnancy and concluded that the drug does not cause any side effects associated with its use. 40-41 Crawford and Lewis state that “...we believe that the view that women in the first and second trimesters of pregnancy should not inhale nitrous oxide without first administering folic acid is unjustified and causes unnecessary stress and anxiety among women of childbearing age.” age and their medical representatives.” 40 Even in cases where oocyte retrieval for subsequent artificial insemination in vitro was carried out under anesthesia using nitrous oxide, the frequency of chromosomal abnormalities and the index of successful fertilization remained unchanged. 42

Data on the use of nitrous oxide can be summarized as follows. First, nitrous oxide may have a teratogenic effect in animals, which is most likely due to a decrease in uterine blood flow rather than inhibition of methionine synthetase activity. The use of halogenated general anesthetics helps prevent a decrease in uterine blood flow. Second, some studies do not show that folic acid is protective, although daily maintenance doses of folic acid do reduce the overall incidence of neurological defects at birth. And third, despite the fact that nitrous oxide can cause teratogenic effects in animals under certain dosage regimens, nitrous oxide has not been proven to be teratogenic in humans.

Effect of anesthetic agents on personnel in the operating room

An alternative way to study the effects of anesthetics during pregnancy is to study the effects of inhalational anesthetics on operating room or dental personnel. The atmospheric air in the dental office and operating room is contaminated with vapors of gaseous anesthetics; In the literature, there is evidence that women working in such conditions are more likely to have miscarriages, and their children are more likely to have congenital anomalies. 43,44 A recent study sought to examine the effects of high concentrations of nitrous oxide on women working in dentistry; It turned out that this category of people had a significantly reduced reproductive function, which was assessed based on counting the number of menstrual cycles required for pregnancy. 45

However, retrospective studies may be subject to methodological errors. For example, one study found that the rate of spontaneous miscarriage among members of the population who do not encounter inhalational anesthetics in their daily lives was 31 percent. 46 In contrast, many studies of the harmful effects of inhalational anesthetics on health care personnel report significantly lower spontaneous miscarriage rates (3.5–10.5 percent) in control groups. This may be partly due to the fact that women whose work involves contact with inhalational anesthetics are aware of the harmful effects of the latter on the reproductive function of the body and have a better understanding of the consequences this can lead to. Another weakness of retrospective studies is the lack of strict criteria determining the nature or duration of anesthetic effects, as well as their concentration (these criteria vary greatly, depending on several factors, For example on the range of tasks within the competence of this specialist ( For example one doctor specializes in performing mask anesthesia, the other performs regional blockades), the anesthetic equipment used, the effectiveness of cleaning systems). All this complicates the process of creating a representative control group of subjects. Researchers may not take into account other factors such as stress, radiation exposure, maternal age, smoking, obstetric history, and comorbidities such as diabetes.

In our review of studies published before 1985, we found a large number of inaccuracies in study designs. 47 Among them are the lack of clear criteria for the duration and nature of the effects of anesthetics, underestimation of the influence of potential associated factors, and much more. Some authors of these studies have concluded that there is insufficient evidence to suggest that exposure of operating room personnel to inhalational anesthetics results in an increase in spontaneous miscarriages or congenital anomalies.

In later work, an attempt was made to eliminate previous shortcomings, and as a result it was found that in women whose professional activity is related to work in the operating room, the likelihood of miscarriage and the occurrence of congenital anomalies in the child does not increase, the risk of having children with underweight does not increase, and there is no increase in perinatal mortality. In one such study, the study involved nurses working in the operating room who had experienced miscarriages or fetal abnormalities; As a result, it turned out that in this category of people the nature of the action and dose of inhalational anesthetics were no different from those that affected nurses who constantly worked in the operating room and gave birth to normal newborns. 48 Another study compared the stress levels of nursing staff in an operating room with those of nurses in a regular medical ward; It turned out that the frequency of miscarriages, fetal anomalies and the level of perinatal mortality in the compared groups were the same. 49 Nowadays, operating rooms are widely equipped with air filtration and purification systems, and therefore there is little reason to believe that constant contact with inhalational anesthetics in the operating room poses a health hazard during pregnancy.

Consequences of surgery during pregnancy

Surgery during pregnancy increases the risk of miscarriage. 50,51 There are several reasons for this; surgical intervention can lead to intrauterine death of the fetus, provoke premature birth or contribute to the occurrence of certain anomalies. No studies have established a direct link between surgery and the occurrence of congenital anomalies, but there is convincing evidence that fetal anomalies (often incompatible with life) are often the main cause of premature birth. What is the cause of fetal death - unfavorable preoperative background, surgical aggression or anesthesia? Some studies have examined follow-up data from women who underwent surgery during pregnancy; these works were aimed at establishing the causes of fetal death.

One such work was carried out in Canada, where health insurance contracts for the period 1971-1978, concluded by various insurance companies with more than 2,500 women who underwent surgical interventions during pregnancy, were retrieved from the archives; the data obtained were compared with the results of a survey of the same number of patients whose pregnancy proceeded smoothly, without surgery. 52 As a result, it was found that the risk of congenital anomalies does not increase, but the risk of spontaneous miscarriage increases in those women who underwent surgery under general anesthesia in the first or second trimester of pregnancy (risk score was 2 for gynecological interventions and 1.54 for operations on other organs). The risk of miscarriage did not increase in the group of women who did not receive any general or local anesthetics during pregnancy and who did not undergo spinal blockade. The authors of the work concluded that surgery has a significant impact on the course of pregnancy, especially when it is performed on reproductive organs, and general anesthesia itself is a risk factor. 53

Even more comprehensive work was carried out in Sweden, where 5,400 pregnant women who underwent surgery were examined between 1973 and 1981. 2 Again, studies have shown that surgery during pregnancy is not associated with an increased incidence of congenital anomalies; however, it appears that perinatal mortality rates are increasing and low birth weight (less than 1,500 grams) babies are being born more often, even if the surgery was performed well before birth. No analgesic method has been identified as presenting a particular risk to the fetus. On the contrary, the risk of any undesirable consequences during general anesthesia was even below, than it was assumed, which gave the authors grounds to talk about the “protective effect” of general anesthesia. The researchers concluded that the disease that caused the surgery is the main factor influencing the course of pregnancy. Since nitrous oxide was used in 98 percent of general anesthesia, the authors concluded that nitrous oxide was neither toxic nor teratogenic. In a smaller subgroup of patients who underwent appendectomy during pregnancy, similar results were obtained - the risk of congenital anomalies does not increase, and the frequency of spontaneous miscarriages increases during the first week after the operation. 54

Unfortunately, none of these studies have been able to determine the exact cause of miscarriages. Preterm birth in the postoperative period (which is identified in the above-mentioned studies as the main cause of fetal death) was most likely due to the presence of an unfavorable premorbid background before surgery and was not associated with the use of any anesthetic, a particular method of anesthesia, or a particular technique. operations. Intra-abdominal pathology, pathology of the pelvic and uterine organs pose the highest risk during pregnancy.

To summarize all that has been said, we note that not a single drug used in anesthesiology, with the exception of cocaine, has so far been designated as having a teratogenic effect in humans. Table 1 lists drugs classified as teratogenic by the American Association of Obstetricians and Gynecologists. 5 Please note that this list does not contain any anesthetics other than cocaine, which will be of interest to those anesthesiologists who specialize in providing pain management to women during pregnancy. However, it must be remembered that hypoxia 55, hypercapnia and hypotension (impairing uterine blood flow) contribute to the occurrence of developmental abnormalities and can lead to fetal death at any stage of gestation.

Carrying out anesthesia in patients with surgical pathology during pregnancy

Preoperative examination

Tables 2 and 3 present the basic principles of patient management in early and late pregnancy. The choice of the most adequate method of pain relief is made taking into account whether pregnancy has been verified in a particular patient with surgical pathology. An anesthesiologist, when visiting his patient of childbearing age in the preoperative period, in all cases is obliged to inquire whether she is pregnant. If there is any doubt, a pregnancy test should be performed. Unpublished data suggest that only about 10 percent of anesthesiologists and surgeons are interested in the date of last menstrual period (LMP). 56 The anesthesiologist is required to indicate the DPM in the medical history.

If possible, elective surgical intervention should be postponed until the second or third trimester of pregnancy in order to protect the fetus from exposure to anesthetics during the period of organogenesis (up to the 13th week of gestation). One study examined the risk of cholecystectomy during pregnancy, 57 with nine patients undergoing surgery for cholecystitis at different stages of pregnancy. In three of them the operation was performed in the first trimester; In two women, miscarriage occurred shortly after surgery, and in one, spontaneous termination of pregnancy occurred 3 weeks after surgery. Three patients were operated on in the third trimester of pregnancy; in two of them the birth was premature and occurred shortly after the operation, in one patient the birth was urgent. The last three patients underwent surgery in the second trimester of pregnancy, and all of them gave birth to healthy babies at term. These data may indicate that when surgery is performed in the second trimester of pregnancy, the risk of premature birth is lower than when surgery is performed later in pregnancy, since in later periods of gestation the uterus becomes more susceptible to the effects of various irritants.

During the preoperative assessment, the anesthesiologist and surgeon discuss whether surgery may cause spontaneous premature termination of pregnancy and what risk it poses to the fetus; In addition, the patient should be reassured that the anesthetics or pain relief techniques used will not cause significant harm to the fetus. Use effective premedication regimens that sufficiently reduce anxiety, make the mother feel more comfortable, and also prevent the release of endogenous catecholamines, which can reduce uterine blood flow. Opioids and barbiturates can be used safely even in early gestation. If the clinician intends to use benzodiazepines, he or she should first become familiar with the contents of the accompanying package insert. Having decided to use agents that reduce salivation, it is necessary to remember that glycopyrrolate does not have a compromising effect on the hemodynamics of the maternal body; in addition, neither atropine nor glycopyrrolate have any adverse effects on the fetus. 58 In the preoperative period, it is necessary to prevent aspiration complications. using for this purpose a combination of a nonspecific antacid, an H2 receptor blocker and metoclopramide (cerucal). The administration of paracetamol helps reduce the rate of gastric emptying in the first trimester of pregnancy. 59

For preventive purposes, the obstetrician may prescribe tocolytic (labor-reducing) drugs. For this, suppositories with indomethacin are most often used; The anesthesiologist, as a rule, does not participate in such purely obstetric activities. 60 However, before administering β-agonists or magnesium sulfate, their effects on hemodynamics and interactions with anesthetic drugs should be assessed. The patient needs to be told about the symptoms of preterm labor, such as back pain, since in the postoperative period this makes it possible to detect the onset of preterm labor at an earlier date. Finally, if the gestation is greater than 20 weeks, strongly encourage your patient to lie on her left side during transport to the operating room to avoid compression of the inferior vena cava and abdominal artery.

Carrying out anesthesia

During the operation, it is mandatory to monitor the mother's blood pressure, oxygenation (based on FI O2 and pulse oximetry), ventilation (preferably based on end-tidal CO 2) and temperature. Try to avoid hypoglycemia. After the 16th week of gestation, if possible, use an external Doppler sensor to measure the fetal heart rate and a tocodynamometer to measure uterine contractility, if the place of their attachment does not interfere with the operation. 61 In cases where surgery is performed on the abdominal and pelvic organs, the Doppler sensor, after preliminary sterilization and wrapping, is fixed in a special way, which makes it possible to monitor fetal heart sounds.

The anesthesiologist must explain to surgeons and obstetricians why such close monitoring of the fetus is carried out during surgery. Observation is Not aims to determine when and how labor will begin, as happens in obstetric practice when dealing with a patient giving birth. Monitoring the vital functions of the fetus allows you to once again make sure that the environment existing inside the uterus is optimally suitable for the fetus. For example, a slowing of the fetal heart rate during surgery may indicate unintentional maternal hypoxia, which can be corrected by increasing FI O2 or repositioning the endotracheal tube. 62 Most likely, it is hypoxia that is the most stressful factor for the fetus during surgery and the most common cause of developmental anomalies. A slow fetal heart rate may also indicate inadequate uterine blood flow, which can be increased by increasing lateral displacement of the uterus to the left or by increasing mean maternal blood pressure using infusion or pressor drugs (such as ephedrine). In cases. when the operation is performed under controlled hypotension or accompanied by cardiopulmonary bypass, it is the fetus that is the most reliable monitor to assess the adequacy of blood flow in the mother’s body. 63 Opioids, barbiturates, and other anesthetics can cross the placental barrier and affect the fetal heart rate during surgery. This can continue in the postoperative period until these drugs are completely excreted from the fetal body (the mother’s body is usually freed from them at an earlier date). 64 In this regard, assessing the condition of the fetus in the postoperative period is sometimes a difficult task.

There is no reason to believe that any specific drug or particular anesthetic technique is superior to others as long as maternal tissue perfusion (blood pressure and cardiac output) and oxygenation are maintained within normal limits. In other words, it is necessary to try by all means to avoid hypoxia and hypotension. When performing anesthesia, try to think first of all about its safety, and not about which drugs or techniques will be most appropriate. Decreased maternal blood pressure, mechanical ventilation, 65 pain or anxiety, increased uterine activity, and use of vasoconstrictors, 66 all lead to decreased placental blood flow.

Ideally, the administration of general anesthetic begins 5 minutes after the onset of preoxygenation, which helps prevent a rapid decrease in saturation. The rapid sequence induction technique combined with cricoid pressure reduces the risk of aspiration. If ketamine is used as the main anesthetic for induction, then in early gestation it is administered in doses of less than 2 mg/kg to prevent increased uterine tone. 67,68 Ketamine does not increase uterine tone in late pregnancy. Inhalational anesthetics are usually used to reduce uterine tone and contractility. This is especially desirable when performing various manipulations on the abdominal and pelvic organs, but it has not yet been proven that the use of inhalational anesthetics can reduce the incidence of preterm birth. When halogenated anesthetics are used in doses of 2 MAC or higher, there is a decrease in blood pressure and cardiac output in the mother, which leads to acidosis in the fetus. 69,70 Due to the fact that nitrous oxide may reduce uterine blood flow 38,39 and reduce the activity of methionine synthetase, some scientific centers recommend refraining from its use in the first trimester of pregnancy or prescribing folic acid for prophylactic purposes in the preoperative period. 33 As stated previously, there is no convincing evidence to justify such recommendations, and some animal studies have shown that all of the unwanted effects of nitrous oxide can be counteracted by the addition of an inhalational anesthetic. When deciding to eliminate residual neuromuscular blockade associated with the use of non-depolarizing muscle relaxants, it must be remembered that drugs such as pyridostigmine, neostigmine and edrophonium have a quaternary structure and therefore do not pass through the placenta and do not cause bradycardia in the fetus. However, theoretically, they can increase uterine tone indirectly, as they help increase the release of acetylcholine. These drugs should be administered slowly in combination with an anticholinergic agent such as glycopyrrolate. Summarizing all of the above, we note once again that the features of general anesthesia in pregnant women with surgical pathology are the use of the method of rapid sequential induction, the use of high concentrations of oxygen and acceptable combinations of a narcotic analgesic, an inhalational anesthetic and a muscle relaxant.

The use of various methods of regional anesthesia, especially spinal blockade, is associated with minimal drug exposure to the fetus, which is very important in the first trimester of pregnancy. If no additional sedative or narcotic drugs are administered, then there is no need to talk about their effect on the embryo, and therefore, the condition of the fetus in the postoperative period is fairly accurately assessed by the rhythm of its heartbeats. Adequate pre-infusion load and constant lateral displacement of the uterus to the left side help avoid hypotension. It must be remembered that the need for local anesthetics during pregnancy decreases already in the first trimester. 71 If it becomes necessary to administer a pressor, ephedrine is preferred because it does not affect uterine blood flow, although there are indications that phenylephrine has been successfully used as a pressor in some patients during cesarean section without affecting the fetus. . 72.73

Postoperative follow-up

In the recovery room, monitoring of the fetal heart rate and spontaneous activity of the uterus continues. Sometimes it may be appropriate to entrust this task to a specially trained nurse-midwife. Anesthetics or pain control agents that have not been eliminated from the body in the postoperative period can dull the pain associated with uterine contractions, and therefore monitoring of uterine contractile activity must be continued for at least 24 hours after the end of the operation in order to detect the onset of premature delivery and begin the necessary preemptive therapy as early as possible. Epidural or intrathecal administration of narcotic analgesics is an excellent method of combating pain in the postoperative period, which does not require additional systemic administration of sedatives to the mother’s body, and therefore the fetal heart rate remains unchanged. The pediatric service must be informed of the surgical intervention and the possibility of premature birth.

ABOUTbeaning

To summarize all that has been said, we note that pregnant patients with surgical pathology must be treated with attention and respect, and not with fear. The likelihood of teratogenic complications when using various painkillers is either extremely small or completely absent. The concept of adequate pain relief during surgical interventions during pregnancy implies high professionalism of the anesthesiologist and a rational, safe approach to any anesthesia, which is more important than the choice of a specific drug or anesthesia technique.

Table 1. Drugs classified as teratogenic