Features of the course of pneumonia in pregnancy

One of the priority areas in the development of national healthcare is ensuring safe motherhood and childhood. This issue is extremely relevant due to the decrease in the population of healthy mothers, which leads to an increase in perinatal pathology.

The development of pathology in the perinatal period in 99.5% of cases is associated with conditions that arise during pregnancy, during childbirth and appear at the time of birth of the child, and only in 0.5% of cases does this occur during the first week of life.

Today, it has been proven that almost all pre-pregnancy chronic diseases lead to systemic changes in hemodynamics and microcirculation during the formation of the fetoplacental circulation, resulting in fetoplacental insufficiency (FPI). Fetoplacental insufficiency is a clinical syndrome caused by morphological and functional changes in the placenta against the background of disturbances in the mother's body and is manifested by fetal hypoxia and impaired growth and development. The most common cause of fetoplacental insufficiency is extragenital pathology of the mother.

Extragenital pathology is a large group of diseases or conditions that to varying degrees affect maternal and perinatal mortality rates, the frequency of complications during pregnancy, childbirth and the postpartum period, and perinatal morbidity.

In the structure of causes of maternal mortality in Ukraine in 2007, extragenital pathology accounted for 27.7%; bleeding - 25.3%; preeclampsia/eclampsia - 14.4%; amniotic fluid embolism - 10.9%; pulmonary embolism - 12.1%; sepsis - 4.8%; other causes - 4.8%. As can be seen from the data provided, almost a third of women die from extragenital pathology.

Among the causes of maternal mortality from extragenital pathology, the first place is occupied by infections - 36.3%; then - diseases of the circulatory system - 31.8%, digestive organs - 13.6%; malignant neoplasms - 13.6%.

Mortality of pregnant women and women in labor from lung diseases (mainly from pneumonia) ranks third (13%) after cardiovascular diseases (28.5%) and acute viral hepatitis (18.6%). Among the causes of death from infectious diseases, pneumonia ranks first.

The wide prevalence of extragenital pathology and the diversity of nosological forms complicating the course of pregnancy required the mandatory inclusion of a new link in the classical chain of interaction "obstetrician - gynecologist - pregnant woman" - a therapist or a narrow specialist. Such interaction helps to provide assistance to the mother and child at a qualitatively new level due to the choice of a strategy for the treatment of extragenital pathology taking into account the physiological changes in the female body, the development of tactics of management, optimal timing and methods of delivery with maximum safety for the life of the mother and child.

One of the current areas of such interdisciplinary interaction is pregnancy management against the background of respiratory system pathology. In a situation where "the mother breathes for two", pneumonia is especially dangerous as the most common cause of acute respiratory failure (ARF) during pregnancy.

The prevalence of community-acquired pneumonia among pregnant women ranges from 1.1 to 2.7 per 1000 births, which does not exceed the rates among non-pregnant women aged 20 to 40 years. The development of pneumonia during pregnancy increases the risk of complications for the mother and fetus, while mortality rates are comparable to those in the general population.

The situation changes when it comes to periods of influenza A epidemics. Experience from the largest influenza epidemics of the 20th century has shown that the highest morbidity and mortality during the epidemic period is typical for pregnant women. Clinical manifestations of acute respiratory viral infection (ARVI) and influenza in pregnant women do not differ from those in a comparable age population of non-pregnant women, but by the third trimester the risk of hospitalization increases even for women without risk factors.

According to data from the California Department of Public Health for April-August 2009 (the period of the California H1N1 flu epidemic), 10% of the 1,088 hospitalized were pregnant women, 57% of whom were in the third trimester.

The development of influenza A during pregnancy has always increased the risk of complications such as premature birth, acute respiratory distress syndrome, and increased maternal and infant mortality rates.

Pregnant women make up only 1-2% of the general population, and 7-10% of patients hospitalized during the H1N1 flu pandemic. According to FDA data, from April 14 to August 21, 2009, 15% of all patients with confirmed H1N1 flu were pregnant.

It is important to emphasize the fact that pregnancy as a physiological state of the female body is not a risk factor for the development of pneumonia, but is associated with a large number of complications of this disease. In order to understand the features of the course of pneumonia in this group of patients, it is necessary to consider in more detail a number of physiological changes in their respiratory system, gas exchange and immunity.

Physiological features of the respiratory system during pregnancy. Changes in the respiratory system begin as early as the first week of pregnancy. Due to the secretion of progesterone, changes in respiratory volumes and sometimes in the frequency of respiratory movements occur. Similar phenomena can be observed in non-pregnant women in the luteal phase of the cycle or when progesterone is prescribed to them.

Due to the pregnant uterus, the diaphragm rises by 4 cm, while its excursion does not change. The functional residual capacity of the lungs decreases by 20%. Maximum ventilation of the lungs increases throughout pregnancy and by the time of delivery increases by 20-40%, alveolar ventilation increases by 50-70% to compensate for respiratory alkalosis, developing under the influence of progesterone.

Blood gas composition. During pregnancy, oxygen consumption increases by 33%.

Physiological hyperventilation leads to the development of respiratory alkalosis - Pa CO2 = 28-32 mm Hg, while Pa O2 should be maintained at 105 mm Hg. Minor changes in the gas composition of the mother's blood lead to significant changes in fetal oxygenation. The body's need for oxygen during pregnancy increases by 15-20%, while the reserve volumes of the lungs decrease. Thus, increased oxygen consumption and a decrease in the compensatory capabilities of the respiratory system are factors predisposing to the development of severe respiratory failure. The risk of transfer to artificial ventilation in the event of pneumonia in patients of this group increases by 10-20%. The development of severe hypoxia against the background of pneumonia is the third most common indication for intubation among all obstetric patients.

Immunity. During pregnancy, there is a decrease in the cytotoxic activity of lymphocytes, a decrease in the number of T-helpers and a decrease in the activity of NK-killers, which increases susceptibility to viral and fungal infections. Pregnant women with foci of acute and chronic infection are characterized by suppression of cellular immunity and the absence of an adequate response from humoral immunity. Pregnancy increases the risk of flu complications by 50%.

The increased incidence of influenza among pregnant women is associated not only with physiological and immunological changes in the mother's body, but also with the constantly changing antigenic structure of the virus.

The H1N1 influenza pandemic showed that patients in the third trimester of pregnancy and women in the early postpartum period are most susceptible to this virus. According to the California Pandemic (H1N1) Working Group, 22% of the total number of observed patients (102 women) required hospitalization in the intensive care unit (ICU) and respiratory support. The mortality rate among pregnant women at the end of the 2009 pandemic was 4.3 maternal deaths per 100,000 live births.

Among the risk factors for the development of pneumonia that are not related to the physiology of pregnancy, the most significant are HIV, cystic fibrosis, anemia, steroid use, including for obstetric indications, bronchial asthma (detected in 16% of pregnant women hospitalized for pneumonia during the California H1N1 flu epidemic), and the third trimester of pregnancy (according to various studies, 50 to 80% of pneumonia cases occur during this period).

As a consequence of respiratory failure, the most serious complications of pneumonia are acute fetal distress, antenatal fetal death, premature birth with low birth weight babies (less than 2500 g in 36% of cases).

In newborns of mothers with pneumonia against the background of H1N1 influenza, intrauterine pneumonia, cerebral ischemia, intraventricular hemorrhage, convulsive and vegetative-visceral syndrome, transient myocardial dysfunction more often developed. Complications arising against the background of this pathology lead to an increase in infant mortality rates; depending on the studies conducted, it ranges from 1.9 to 12%.

The aim of this study was to determine the characteristics of the course of pneumonia during pregnancy and the effectiveness of the PSI, CURB-65 and Coopland scales in assessing the condition of pregnant women, to identify groups and risk factors for the development of severe respiratory failure, and to develop an algorithm for managing patients with ARVI symptoms from the perspective of a general practitioner.

A total of 25 case histories of pregnant women who had been treated in the intensive care unit and/or the pregnancy pathology department (PPD) for the period from October 2009 to March 2011 were selected. The patients were divided into two groups: those who had been treated in the intensive care unit (n = 18) - the first group, and those who had been treated in the PPD (n = 7) - the second group. The average age of pregnant women in the first group was 29±3.3 years, in the second group - 23±6.7 years.

Data analysis showed that 88% of patients were in the third trimester of pregnancy at the time of illness. In both the first and second groups, women with extragenital pathology predominated - 67% and 72%, respectively. All patients treated in the intensive care unit were hospitalized during the 2009-2010 flu epidemics, only 3 had virologically confirmed influenza A H1N1.

According to the order of the Ministry of Health of Ukraine dated 19.03.2007 No. 128 "On approval of clinical protocols for providing medical assistance in the specialty "Pulmonology"", the PSI and CURB-65 scales are used to assess the severity of the patient's condition with pneumonia and determine the level of medical care.

A retrospective assessment of the condition of pregnant women at the time of admission to the intensive care unit or hospital showed that, according to the CURB-65 scale, 50% of patients hospitalized in the intensive care unit were subject to outpatient treatment, 48.2% were subject to hospitalization, and only 1.8% met the criteria for treatment in the intensive care unit. 100% of patients in the second group scored 0 points on CURB-65, i.e. were subject to outpatient treatment.

A similar picture was obtained when using the PSI scale. Of the 18 patients hospitalized in the intensive care unit, 16 scored no more than 70 points (risk groups I and II) - an indication for outpatient treatment, 1 patient was assigned to group III (hospital treatment) and 1 to IV (intensive care unit treatment). All pregnant women treated in the intensive care unit were assigned to risk group I according to the PSI scale.

According to the order of the Ministry of Health of Ukraine dated 28.12.2002 No. 503 "On improvement of outpatient obstetric and gynecological care in Ukraine" pregnant women were assessed according to the Coopland scale to determine the level of medical care. All patients belonged to groups of high or very high risk of developing perinatal or maternal pathology. In the first group, the majority (62%) of pregnant women were in very high risk groups, in the second group this category of patients was 42%.

Pregnant women who had been through the intensive care unit were divided into two groups: patients whose first visit to the hospital coincided with the date of hospitalization in the intensive care unit (n = 12); patients who were initially admitted to specialized hospitals (the primary hospital, the obstetric department of the central district hospital) (n = 7).

Features of the group of pregnant women initially hospitalized in the intensive care unit:

• 84% of women were between 30 and 40 years old;
• According to the Coopland scale, 4 patients belonged to the high risk group and 8 to the very high risk group (from 7 to 17 points);
• four patients with the lowest scores in the group on the Coopland scale (5-6 points) were recorded to seek medical help the latest - on the 3rd-4th day from the onset of the disease;
• 50% of patients in the very high risk group according to Coopland are hospitalized in the intensive care unit 24-48 hours after the onset of the disease, which indicates a predisposition of this group of pregnant women to the development of acute respiratory failure;
• In the structure of extragenital pathology in the entire group of patients initially hospitalized in the intensive care unit, chronic pyelonephritis, bacterial vaginosis, and stage I-II anemia predominated.

The main indication for ICU admission was a decrease in Sat O2 to 95%. Venous blood gas analysis data showed that even with Sat O2 within 90-95%, the partial pressure of O2 in venous blood (Pv O2) significantly decreases. For example, with Sat O2 equal to 94%, Pv O2 is 26 mm Hg with a norm of 37-42 mm Hg, which indicates the presence of "latent hypoxia" associated with the features of the hemoglobin dissociation curve.

Oxygenation is characterized by two parameters: hemoglobin oxygen saturation and blood oxygen tension. These parameters are related to each other in a manner determined by the shape and position of the hemoglobin dissociation curve (Figure). The steep section of the curve indicates the possibility of oxygen binding by hemoglobin in the lungs and its release to tissues with small changes in the partial pressure of oxygen (Pv O2). The flat section of the curve indicates a decrease in hemoglobin affinity for oxygen in the region of high Pv O2 values.

Moderate hypoxemia is characterized primarily by a decrease in Pv O2, while blood oxygen saturation changes little. Thus, with a decrease in Pv O2 from 90 to 70 mm Hg, saturation decreases by only 2-3%. This explains the so-called "hidden" or "latent" hypoxia, identified by some authors, when, with pronounced pulmonary respiration disorders, hypoxemia, judging by blood oxygen saturation, is not detected.

The data presented indicate that the use of pulse oximetry alone to determine the degree of hypoxia, especially in patients with extragenital pathology, may lead to an underestimation of the severity of the pregnant woman's condition. Therefore, the examination plan for patients with respiratory pathology during pregnancy with a saturation value of less than 95% should include an analysis of the gas composition of the blood.

Thus, the risk factors for the development of severe pneumonia, especially during influenza epidemics, include: third trimester of pregnancy; age from 30 to 40 years; the presence of extragenital pathology, especially anemia and foci of chronic infection (chronic pyelonephritis, bacterial vaginosis); high and very high risk according to the Coopland scale; late seeking of medical care, leading to a worsening prognosis of the course of the disease even in patients without extragenital pathology.

Given these facts, women in the second and third trimesters of pregnancy should be recommended to get a flu shot, and pulse oximetry should be performed on all patients with pneumonia at each stage of medical care, followed by determination of the blood gas composition in the intensive care unit. Treatment of pneumonia in pregnant women, regardless of the gestational age and the presence or absence of extragenital pathology, requires dynamic monitoring by both an obstetrician-gynecologist and a therapist. Therefore, the optimal treatment regimen for this category of patients is inpatient.

Prof. T. A. Pertseva, Assoc. Prof. T. V. Kireeva, N. K. Kravchenko. Peculiarities of the course of pneumonia during pregnancy // International Medical Journal No. 4 2012

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