Vacuum-hypothermic fetal extraction.

The risk of fetal injury during operative delivery through the natural birth canal is always present, but this risk increases sharply against the background of fetal hypoxia (asphyxia). In addition, obstetric operations themselves cause reflex changes in fetal cardiac activity, expressed to varying degrees and resembling those in asphyxia. Literature data and obstetric practice show that surgical interventions during labor are often combined with fetal asphyxia. In many cases, operations are used for threatened or incipient asphyxia of the intrauterine fetus, as well as in such conditions of the mother (late toxicosis, hemorrhage, etc.), which in themselves threaten the fetus with asphyxia.

For a long time, many obstetricians considered mechanical trauma that occurred during obstetric operations to be the main cause of birth trauma with consequences in the form of asphyxia, cerebral hemorrhage or neurological symptoms in newborns.

Currently, there are more and more reports that the main cause of damage to the central nervous system of the fetus is intrauterine asphyxia, which occurs due to various reasons, which can lead to severe circulatory disorders, up to the appearance of cerebral hemorrhages and ruptures of the cerebellar tentorium.

In recent years, the developed method of craniocerebral hypothermia of the fetus during childbirth has been successfully used to treat fetal asphyxia.

In modern biology and medicine, to increase the resistance of brain tissue (which, as is known, suffers first of all from hypoxia of the organism) to oxygen deficiency, to prevent the development of hypoxia and to eliminate its pathological consequences, a reliable method is considered to be a decrease in brain temperature - "hypothermia", which allows to temporarily and reversibly transfer the organism to a reduced level of vital activity. Numerous studies have proven that under conditions of a moderate decrease in brain temperature, oxygen consumption by its tissues decreases by 40-75%.

During the process of cooling a person, the body's oxygen consumption decreases by 5% with each degree of temperature decrease. Under the influence of hypothermia, the connection of oxygen with hemoglobin increases, and the solubility of carbon dioxide in the blood increases.

Cranio-cerebral hypothermia, compared to general hypothermia, allows to reduce the risk of complications from the respiratory and cardiovascular systems with the same or even deeper cooling of the brain, since a significant gradient is achieved between the temperature of the brain and the body. Experiments by Parkins et al. (1954) showed that against the background of hypothermia of the brain (32°), animals painlessly endure a 30-minute shutdown of the heart from the blood circulation. Similar results were also obtained by Allen et al. (1955). According to Duan-Hao-Shen (1960), when cooling the head (30°) in experimental animals, the cessation of blood flow to the brain through the cervical-cerebral arteries for 40-60 minutes did not lead to irreversible changes. At a brain temperature of 30.1-27.1° C (respectively, in the rectum 33-34° C), blood filling decreased by 40-50%; with deep hypothermia, it decreased by 65-70%.

Studies indicate a decrease in the blood flow rate in the cerebral vessels during cranio-cerebral hypothermia. During this process, slow potentials gradually appear on the electroencephalogram, and the bioelectrical activity of the brain is suppressed. According to the author, with moderate hypothermia, i.e. a decrease in the temperature of the brain to 28°C, the intensity of blood flow in the main vessels decreased by half. The amount of blood entering the brain decreased the faster the temperature decreased. The most important result of the action of cranio-cerebral hypothermia is its ability to significantly extend the time of use of oxygen reserves and maintain functional activity in conditions of its insufficiency. The conditions created by cranio-cerebral hypothermia should be considered gentle, switching the activity of vital functions of the body to a new, more economical level.

Conducting craniocerebral hypothermia in hypoxic conditions in a clinical setting has several goals:

• reducing the body's and, in particular, the brain's need for oxygen;
• prevention or elimination of cerebral edema due to restoration of blood flow and microcirculation in the cerebral vessels;
• restoration of the balance between the formation and removal of H ⁺ ions.

Hypothermia, causing a decrease in oxygen consumption by brain tissue, does not reduce its ability to absorb oxygen. The positive quality of craniocerebral hypothermia should be considered the possibility of rapid, effective hypothermia over a relatively short period of time.

The basis for the development and introduction into clinical practice of the method of craniocerebral hypothermia of the fetus and newborn in hypoxic conditions were the observations of a large number of authors who proved the harmlessness of cooling the fetus during hypothermia of the mother's body, through which the temperature of the fetus was lowered. Hypothermia was performed on pregnant women when there were indications for surgery due to severe diseases of the cardiovascular system and brain. The safety of cooling the mother's body for the fetus was shown in experimental studies, which showed that the cessation of blood circulation in the mother and a drop in temperature below 0 ° are compatible with the normal development of the fetus, with the exception of the stage of pregnancy when the hemochorial placenta is formed. Animals subjected to cooling during intrauterine development subsequently had normal offspring. Experiments on dogs showed that a decrease in uterine blood circulation during general hypothermia does not worsen the condition of the fetus. The authors come to the conclusion that hypothermia increases the resistance of the fetus to hypoxia, since due to a decrease in temperature, metabolic activity and oxygen consumption are sharply reduced.

Newborn animals are much more resistant to cold. This was shown in the experiments of Fairfield (1948), who reduced the body temperature of newborn rats to + 2.5", while in some observations they had no heart contractions for an hour and no oxygen consumption was observed, while the animals survived. According to Davey et al. (1965), Kamrin, Mashald (1965), Herhe et al. (1967), during intracranial operations in pregnant women under general hypothermia, pregnancy and childbirth proceeded without complications. After the operations, no negative effects on the fetus and its further development were observed. Hess, Davis (1964) conducted continuous recording of the ECG of the mother and fetus during an operation on a pregnant woman under general hypothermia. Observation continued for 16 hours - from the onset of hypothermia until normal temperature was restored. As the temperature decreased, there was a decrease in blood pressure and a slowdown in the mother's pulse, a decrease in the fetal heart rate. After the start of warming, the initial parameters gradually returned to the initial level. One month after the operation, term labor occurred. The child's Apgar score at birth was 7. Barter et al. (1958) described 10 cases of hypothermia during cesarean section due to eclampsia, with a favorable outcome for the mother and fetus. Herhe, Davey (1967) did not find any deviations in the psychomotor development of the child during a special psychological examination of a 4-year-old child, whose mother underwent intracranial surgery under general hypothermia at 36 weeks of pregnancy. The use of the method of cranio-cerebral hypothermia of the fetus during labor, undertaken for the first time in obstetrics by K. V. Chachava, P. Ya. Kintraya et al. (1971) made it possible to conduct cryotherapy of the fetus during its hypoxia, when other methods of influencing the fetus in order to improve its functional state were ineffective. According to the data of P. Ya. Kintraya et al. (1971) found that the use of this method in complicated births reduced perinatal mortality by 24.3%. A. A. Lominadze (1972) concluded that during craniocerebral hypothermia of the fetus during labor, the functional state of its cardiovascular system improves, resistance and tone of the cerebral vessels are normalized, intracranial pressure decreases, and cerebral circulation improves. Clinical, neurological, and electrophysiological (ECG, EEG, REG) examination of children who suffered intrauterine asphyxia against the background of craniocerebral hypothermia confirmed that the use of this method prevents the development of irreversible changes in the fetal brain, helping to accelerate the recovery processes in the central nervous system of the newborn. At the same time, in the neonatal period, there was a gradual increase in body temperature after hypothermia (over 48 hours). This can be assessed positively, since the normalization of metabolic processes in the tissues of the central nervous system after asphyxia occurs comparatively more slowly.A lower brain temperature thus reduces the tissue's need for oxygen not only during asphyxia, but also in the subsequent period of recovery of impaired functions.

In cases of fetal asphyxia during labor and the need for operative delivery through the natural birth canal, modern obstetrics uses obstetric forceps or vacuum extraction of the fetus. Instrumental extraction of the fetus is an extreme obstetric measure. As K. V. Chachava wrote (1969), the obstetrician takes up instruments in cases where the health and life of the mother and fetus are at risk. If we are talking about indications for surgery due to the threatening condition of the fetus, then this is primarily asphyxia, circulatory disorder. Forceps and a vacuum extractor are designed in such a way as to reliably fix the head for subsequent traction. And such fixation does not pass without a trace for the newborn and in itself can cause asphyxia and cerebral circulatory disorders.

In case of operative delivery, compared to spontaneous delivery, the frequency of perinatal morbidity and mortality naturally increases. Thus, according to Friedbeig (1977), the results of the analysis of 14,000 births showed that in case of delivery by caesarean section in full-term pregnancy, children with a low score on the Apgar scale are more often born (21.5%). Caesarean section operation not only negatively affects the child's adaptation to extrauterine existence in the first minutes of life, but also the course of the entire early neonatal period. Thus, the frequency of perinatal mortality in women delivered by caesarean section was 3.8%, in case of spontaneous delivery - 0.06%.

Obstetric operations performed for delivery through the natural birth canal are especially dangerous for the fetus. Among the methods of operative delivery through the natural birth canal, one of the most frequently used today is the method of vacuum extraction of the fetus. It should be noted that in some cases, in order to obtain a living child, vacuum extraction is the only possible delivery operation. According to Altaian et al. (1975), the perinatal mortality rate when using obstetric forceps was 2.18%, and with vacuum extraction - 0.95%. The frequency of severe maternal trauma is 16.4% when using obstetric forceps and 1.9% when using a vacuum extractor. According to M.A. Mchedlishvili (1969), the highest mortality rate was found in the group of children delivered by forceps (7.4%), then in the group delivered by Caesarean section (6.3%), and the lowest - when using a vacuum extractor (4.4%). An identical pattern was found in the work of V.N. Aristova (1957, 1962). According to G.S. Muchiev and O.G. Frolova (1979), the perinatal mortality rate in women whose birth ended with the use of forceps was 87.8%, and in the case of vacuum extraction of the fetus - 61%. According to Plauche (1979), when using a vacuum extractor, subaponeurotic hematomas occur in 14.3% of cases, abrasions and skull injuries - in 12.6%, cephalohematomas - in 6.6%, intracranial hemorrhages - in 0.35% of cases. When assessing the frequency of early and late neurological disorders in children, only a slight difference was noted between births using a vacuum extractor and spontaneous births. It was concluded that when technically correct and indicated in each individual case, the vacuum extractor is effective and less traumatic compared to other instrumental methods of delivery.

The vacuum extractor proved to be an effective tool when used as directed and with fewer adverse effects than obstetric forceps. The children were examined using the Brazelton Neonatal Behavior Scale and standard nephrological examinations on the 1st and 5th days after birth. The children extracted using the vacuum extractor responded less well to external stimuli on the 1st day in behavioral tests and gave fewer optimal responses in the neurological examination than the controls. These differences between the groups disappeared on the 5th day. It was found that the lowest perinatal mortality (1.5%) and morbidity (1.6-2.1%) of children were observed in cases where, in the absence of intrauterine fetal asphyxia, the indications for applying forceps were heart disease in the mother or weakness of labor. When forceps were applied for late toxicosis of pregnancy, or threatening intrauterine asphyxia, or a combination of these indications, perinatal mortality and morbidity of children increased by 3-4 times. The latter also increased with an increase in the duration of intrauterine asphyxia. Perinatal mortality also increased with an increase in the duration of labor and the anhydrous period, but such a connection for the morbidity of children during their subsequent development could not be established.

According to K. V. Chachava (1962), who first used vacuum extraction in the CIS countries, during clinical-neurological and electrophysiological examination of children extracted with obstetric forceps and a vacuum extractor, obstetric forceps are a more rude intervention and, together with neurological complications, often cause significant shifts in the electrical activity of the brain, and when using a vacuum extractor, which significantly reduces the possibility of brain injury, the electroencephalogram in most cases is characterized by a normal picture. Examining newborns extracted with obstetric forceps and a vacuum extractor, scientists came to the conclusion that their clinical-neurological status, electrophysiological indicators (ECG, EEG) indicate a greater damaging effect of obstetric forceps compared to a vacuum extractor. When studying the acid-base balance of the blood of the mother and fetus during vacuum extraction, acidosis of the blood of the mother and fetus was revealed during spontaneous and operative deliveries, and vacuum extraction does not have a negative effect on the acid-base balance of the blood of the mother and fetus. A number of researchers noted an increase in the number of newborns with retinal hemorrhages during fetal vacuum extraction compared to spontaneous deliveries. Thus, according to research data, retinal hemorrhages were found in 31% of newborns after spontaneous deliveries and in 48.9% after vacuum extraction. It is believed that the appearance of retinal hemorrhages is associated not so much with the vacuum extraction operation itself, but with the obstetric situation that required this intervention. Vacuum extraction of the fetus is currently the most common among obstetric operations.

It should be noted that many authors, comparing the long-term consequences of the forceps and vacuum extraction operations, do not take into account the position of the head in the pelvis, therefore, a number of studies compare the operation of vacuum extraction of the fetus with the head pressed to the entrance to the pelvis in comparison with cavity or obstetric forceps. When comparing operations performed for the same indications and conditions, many researchers come to the conclusion that the operation of vacuum extraction of the fetus is a more gentle operation for children than the application of obstetric forceps, and most of the unfavorable outcomes when using it are explained by a violation of the rules for performing the operation (rapid formation of a vacuum, continuous traction, their deviation from the pelvic axis and tearing off the cup of the device).

To assess the most subtle deviations in the psyche of preschool and school-age children, they undergo a psychological examination. For this purpose, various tests are used to identify the level of mental development of the child, the type of personality experience, and the child's fantasy. There was no relationship between the coefficient of mental development and the methods of delivery. There was also no relationship between the coefficient of mental development and the frequency of late toxicosis during pregnancy, prolonged labor, or the assessment of the child's condition according to the Apgar scale. The level of mental (56% of children began to speak on average at 18.4 months of life) and physical development (65% of children began to walk at 12.8 months of life) of children was the same.

In conclusion, it should be noted that vacuum extraction and the operation of applying obstetric forceps are not mutually exclusive operations, as some modern authors point out, and each of them has its own conditions, indications and contraindications.

As is known, there are no safe operations for delivery for the fetus and mother. If the fetus is not exposed to the damaging effects of hypoxia, short-term delivery operations of vacuum extraction or forceps, as a rule, do not cause damage to the fetus under favorable conditions for delivery (normal sizes of the pelvis and head, position of the head in the pelvic cavity). In case of fetal asphyxia, the possibility of damage increases with any method of surgical intervention, the degree of which directly depends on both the duration and severity of asphyxia and the duration of the operation. Modern methods of operative delivery through the natural birth canal, despite great achievements in practical obstetrics, are still quite imperfect. Therefore, the invention and introduction into obstetric practice of new delivery instruments that allow for the most careful, atraumatic extraction of the fetus is of no small importance.

An analysis of literature data and our own research show that craniocerebral hypothermia of the fetus during labor is a new, effective method of combating hypoxia, allowing to protect the fetus's CNS from intracranial birth trauma, the risk of which is especially high during instrumental delivery. In addition, most authors come to the conclusion that in case of fetal hypoxia, in combination with other indications for surgical delivery, which, as is known, are often combined, vacuum extraction is a more gentle and in some cases the only possible operation.

Due to the fact that in the domestic literature there are no monographic works on the use of the fetal hypothermia method in obstetric operations to deliver babies and there is no data on the comparative assessment of the cesarean section operation, obstetric forceps and vacuum-hypotherm extractor in perinatal care of the fetus, we provide a detailed description of the vacuum-hypotherm extractor device, as well as the technique of the operation, indications and contraindications for this operation.