Lecture of shock in obstetrics

2021-03-22 12:00 AM

For shock that occurs due to birth complications such as uterine rupture, placenta previa, placental abruption of the first baby, prolonged labor, anxiety, and fatigue.

Changes of pregnant women during pregnancy and labor

Periodic change

Water:

Right from the beginning of pregnancy, pregnant women have kept water in the body. By the 13th week, foreign blood vessels, in the ectopic organs and mammary glands begin to increase until delivery. The total amount of foreign cells increased by about 1.51%. It is characterized here that the water retained in the body is evenly distributed among the soft tissues, and is normally retained in the lower extremities. Water gradually increased and increased significantly in the last 10 weeks until labor and after delivery, it decreased dramatically.

Blood:

The plasma volume increases rapidly and is more foreign than the cell. By the 6th week of pregnancy, plasma volume increases markedly and continues to increase until weeks 30-34. By this time plasma has increased by 50% compared with before pregnancy. Then the volume of plasma remains pooled, unchanged until farrowing. After birth, at 6 weeks, plasma volume returns to normal as before pregnancy. Total erythrocyte volume also begins to increase from month 2 and by 30% by delivery. Considering both the volume of plasma and red blood cells, when the fetus grows, there is a dilution of blood in the blood vessels.

Cardiovascular changes

The woman's heart rate increases gradually with the gestation period. Systolic volume and cardiac output increased gradually and peaked at 28 and 36 weeks, then decreased slightly, but still very high compared to before pregnancy.

Maximum and minimum arterial pressure both decrease by 20 weeks, but gradually return to normal. The reason for the decrease in arterial blood pressure is because more blood vessels develop in the placenta this time. Remember, many women who lie on their back on the delivery table, especially with anesthesia, spinal or epidural anesthesia, can experience sudden heart failure because the aorta is squeezed by the uterus. Insufficient blood to the heart.

Changes in blood clotting and fibrinolysis

This is a problem of much attention when pregnant women reach the delivery period in healthy people, normal pregnancy, also have changes in blood clotting and fibrinolysis. The rate of fibrinogen in the blood increases gradually during pregnancy and is highest at birth (from 3.5 to 5.5g / l). As the plasma volume increases by 50%, the total fibrinogen also increases by more than 50%. Other clotting factors such as thromboplastinogen factors VII, VIII, IX, X also increase in late pregnancy.

In 1970, Coloditz and Josey gave some figures for central venous blood pressure due to the upper thigh vein as follows:

Non-pregnant women: 7.8 - 11.2cm H2O (average: 9cm H2O).

Pregnant women in the first 3 months: 6.8 - 8.2cm H2O (average: 7.7cm).

Middle 3-month pregnant women: 3.6 - 4.6 cm H2O (average 4cm H2O).

Pregnant women in the last 3 months: 2.0 - 4.4cm H2O (average 3.8cm H2O).

Thus, the later in pregnancy, the lower the central venous blood pressure. It is worth noting that when measuring central venous blood pressure, the patient must be considered lying on his back or on his side. If the patient is lying on his back, the venous blood pressure may be blocked, the blood returning to the heart decreases, so the central venous blood pressure will be low.

In 1970, Goltner et al. Monitored the change in central venous blood pressure according to uterine contraction. While the uterus contracts, the central venous blood pressure will increase from 4.5cmH2O to 5.8cm H2O. The reason that central venous blood pressure is higher than normal is that when contracting, the uterus pushes into the vena cava a volume of 250-300ml of blood to bring to the right heart. After giving birth, to the 3rd or 5th day, the central venous blood pressure will increase to 7.5cm H2O, because circulation back to the heart increases more than before.

Fibrinolytic capacity increases during pregnancy, the proportion of plasminogen increases, but plasminogen activators decrease and fibrinolysin inhibitors such as alpha 1 antitrypsin and alpha 2 macroglobulin increase.

It has been found that the mother's blood is temporarily hypercoagulation during labor and especially during delivery.

Respiratory changes

Even in the first few weeks of pregnancy, a woman breathed a lot. The mechanism of increased respiration is considered to be progesterone. Breathing rate increases about 10% compared to before pregnancy. Air circulation increases by about 40%, while the elasticity of the lungs and the living volume does not change. Airway resistance, functional residue volume, and exhaled reserve gas volume decreased. After delivery, lung relaxation will increase from 25 to 30%.

Changes in blood gases

Many works show that during pregnancy until labor and delivery, the blood gases in the blood, hemoglobin oxygen saturation of the pregnant woman are different from the normal person. However, many authors find that the partial pressure of arterial blood oxygen (PaO2) is lower than normal in the last months of pregnancy, because of the arterial-pulmonary shunt, because of an imbalance between respiration and circulation due to an elevated diaphragm. During labor, when pregnant women breathe a lot, the partial pressure of CO2 (PaCO2) will decrease. Parallel to depression, there will be metabolic acidosis. The excess can be as low as - 10Eq / l (if the woman is not adequately relieved).

The risk of reflux

Respiratory obstruction causes acute asphyxiation or Mendelson's syndrome: during labor force the pressure in the pregnant woman's stomach increases.

 

 

The average pressure in stomach (cm H2O)

Centrifugal sphincter resistance maximum (CmH2O)

The pressure difference (cm H2O)

Normally when not pregnant

12,1

34,8

22,7

Pregnant

no heart disease

17,2

44,8

27,6

Pregnant

have heart disease

16,5

23,8

7,3

If the woman is under anesthesia, especially with thiopental anesthesia, the Hiss angle widens, the resistance of the sphincter is no longer, so water and food in the stomach will easily back up, and because the bronchus is also enlarged, so water and food will flow down into the gas - bronchi, causing the above accident. As a result, the lack of oxygen is very severe, and pregnant women can die immediately.

The most common type of shock in obstetrics 

Shock due to blood loss

In obstetrics, blood loss shock is often caused by the following causes:

Broken uterus.

Tearing of the genital tract and episiotomy.

Pour each other.

Sputum of the uterus

Forwards placenta

Young placenta

The course of shock is similar to that of general hemorrhagic shock:

Arterial blood pressure drops.

Rapid pulse.

The whole body was pale.

The nose and extremities are very cold

According to the cause of shock, there are some characteristics as follows:

For ectopic rupture: many women arrive at the hospital, although symptoms of intrauterine bleeding and symptoms of ectopic rupture are evident, arterial blood pressure remains almost normal, The pulse is only slightly fast 120 to 130 times/minute. When the anesthesia is completed and the surgeon operates the abdominal surgery, the arterial blood pressure drops from 100 to 80 mmHg to 0 mmHg, and the abdomen has 1,500-2,000 milliliters of blood or more. This is a reminder that once ectopic pregnancy rupture is suspected, it is necessary to find a definite way to operate immediately, and at the same time find a way to resuscitate so that the shock does not go into the irreversible stage.

For shock caused by complications at delivery such as rupture of the uterus, forward placenta, premature peeling placenta, if the baby is a pig, prolonged labor, worried and tired pregnant women, even though little blood loss: but shock can happen and be very severe. Women who have given birth many times, have fast labor, have less anxiety, can tolerate blood loss better than those who give birth, but once the shock has occurred, the consequences will be more serious, leading to shock. to the stage of not recovering quickly.

By the date of delivery, the number of red blood cells and hemoglobin is low, if there is some anemia, the lower the hemoglobin in the blood and when shocked, the hypoxia will be very severe.

For women who have given birth many times, after giving birth, the uterus shrinks more slowly than women who give birth for the first time, so the amount of blood lost during and after giving birth may be more. Once there is blood loss, lack of oxygen, the uterus becomes stiffer, the more blood loss will be, this is a vicious cycle that makes shock even worse.

Regardless of the cases of embolism due to amniotic fluid, in women with blood clotting disorders such as fibrinolytic or scattered blood clots in the lumen, often shock easily switches to the irreversible stage. The mechanism is as follows: although fibrinogen, other coagulation factors such as thromboplastin VII, VIII, IX, X increase, plasminogen increase, fibrinolysin inhibitors increase, plasminogen activators decrease. but due to rapid and severe hypoxia, severe metabolic acidosis, coagulation factors as well as fibrinolytic factors are susceptible to activation. Clinically, there will be a lot of bleeding in the incision or the vagina and not clotting. The woman is cold, her pulse is fast, difficult to catch, the arterial blood pressure is absent, the lips and limbs are pale. Without timely intervention, the woman will die in a short time.

Septic shock

In obstetrics and gynecology, septic shock is often caused by:      

Common in cases of unsafe abortion.

Sour placenta after giving birth.

There is inflammation in the fallopian tubes and fallopian tubes, or pre-existing genital tract.

Late uterine rupture.

The clinical symptoms are the same as those of septic shock in general.

For unsafe abortion, it is easy to have sepsis or anaerobic infection, or with the associated liver-kidney syndrome. In addition to severe heart failure, pale, pale, or pale lips and extremities, cloudy skin, high fever, chills, dry lips, dirty tongue, jaundice, jaundice, urine. The bacteria that are found are usually anaerobic hemolytic streptococci, which may have a slightly necrotic type of gangrene.

In many cases of late uterine rupture, the patient is in a very toxic infection and when the abdomen is operated on, the pregnant woman has a rotten smell. In most cases, patients are hospitalized with cardiovascular failure. A large number of people died on the operating table or immediately after surgery because the patient suffered both blood loss shock and very serious septic shock.

Shock due to obstruction of amniotic fluid

Amniotic fluid embolism is uncommon, can be seen during normal delivery, or must be intervened by forceps, or cesarean section. Clinically, there are usually three prominent syndromes:

Shortness of breath.

Cardiomyopathy.

Blood clotting disorder.

During labor, women suddenly find it difficult to breathe, lack oxygen, as if someone is blocking the neck. Accompanied by severe chest pain. The pregnant woman panicked, feeling like she was about to die. The whole body is purple, especially the lips and head limbs are purple and black.

Arterial blood pressure absent, pulse not palpable, heart rate very fast and distant. There may be arrhythmias and extrasystole, or ventricular tachycardia.

Parallel to the above symptoms, there is black blood flowing from the vagina or in the incision, the blood rises, flows in a stream, into a pool very quickly. At the hand injection sites, the veins also have a hemorrhage. Taking venous blood into a test tube for 10 - 15 - 30 minutes or longer the blood does not clot, the woman dies quickly. The mechanism is as follows:

Amniotic fluid embolism: The amniotic fluid entering the mother's bloodstream can pass through:

Blood vessels in the cervix.

In the placenta when it is damaged.

The blood vessels when the membranes rupture.

Any blood vessels of the uterus during cesarean section.

Disorders of blood clotting: there are many thromboplastins in amniotic fluid, so when entering the mother's blood, a series of maternal coagulation factors have been activated, causing scattered clotting syndrome in the lumen. On the one hand, due to the natural reaction mechanism when there is strong blood clotting, on the other hand, the mother's plasminogen is elevated during pregnancy, so when activated, it turns into plasmin, causing very heavy fibrinolysis. Here, fibrinolysis can be considered both as the cause parallel with scattered blood clots in the lumen, and secondary to this coagulation syndrome.

Shock due to injury

Due to uterine confusion, is pain shock and blood loss. Anesthesia treatment to reposition.

Diagnose

Diagnosis of shock in obstetrics is similar to trauma shock, blood loss, infection in general, still has to rely primarily on clinical. Clinics include:

A prolonged drop in blood pressure.

Rapid pulse.

Cold nose and extremities.

If septic shock is accompanied by septic syndrome, if it is due to occlusion of amniotic fluid, the above-mentioned respiratory distress syndrome and coagulation disorder are included.

In two cases of septic shock and amniotic shock:

Blood culture, urine culture, vaginal fluid culture, bacteria search (do many times).

Do blood clotting tests. 

Test for blood clotting

Fibrinolytics

Scattered blood coagulation lumen

Clotting time

Howell time

Vonkaulla assayed euglobulin

Platelet count

 

Amount of fibrinogen

Coagulation chart

 

 

Ethanol test

Test protamine sulfate

Fibrin degeneration products

Prolonged

Lengthening (normally 1 min 30)

Very short 15 minutes 30 minutes, (normally over 2 hours)

 

Normally 150.00 - 300,000

 

low or normal

defrosting, a straight line or narrow tuning fork (diapason).

negative

negative

 

below 80 μg / 100ml

Prolonged

Lasts very long

Normal or moderately short.

 

Down as low as 80,000 - 90,000 is very low,

1,5 - 2g/100ml

narrow, rhombohedral or diapason

 

positive

positive

 

over 80 μg / 100ml

If there is no biochemical room, take 2 ml of the mother's venous blood into a test tube for 15 minutes. If there is no clotting or if there is a temporary clot, but when the tube is turned upside down, the clot dissolves immediately, thus either fibrinolysis or a scattered blood clot in the lumen. With this rudimentary method, it is impossible to distinguish the two above disorders.

In parallel with the above tests, it is recommended to do pH tests for blood gases, excess alkalinity, to find ketones in the urine, to evaluate metabolic acidosis. Do liver function tests (bilirubin, control phosphate, SGOT, SGPT), kidney function, blood urea, blood creatinine, urea, albumin density, urinary cylinder, to support treatment.

Prevention and treatment 

Prevention

Must make pregnant women feel more secure and less anxious in the days near giving birth and during labor.

Do not let pregnant women work until the day of delivery.

It is advisable to apply methods of pain relief during delivery such as painless labor exercises, local anesthesia of the shy nerve, anesthesia in the ponytail, for pregnant women to breathe oxygen after a long labor, and difficult delivery.

If an emergency cesarean section is required, endotracheal anesthesia with an oxygen rate of at least 60%.

Pay attention to the woman's position, if lying on her back but blood pressure drops, she must immediately switch to her side. Prevent reflux for newly pregnant women.

Early detection and active treatment of cases of pregnancy poisoning or valvular heart disease.

Iron must be given to pregnant women during pregnancy, if there is severe anemia (red blood cells below 3 million, hemoglobin less than 10g / 100ml).

This is not based on hematocrit, because it is inaccurate. Blood transfusion is required, but preparation is required.

Must choose new blood to take and when taking fasting blood donors, there is no viral hepatitis, use blood from the same group (2 cross tests).

Must give pregnant women a diuretic (Lasix x 20mg), pre-urinate a volume of water at least 500ml before starting blood transfusion. For every 500ml of urine output, 250ml of blood will be injected. To avoid the risk of transmitting too much, do not transmit a large amount at once. In very urgent circumstances should also the only transfusion no more than 500ml of blood (if the patient does not bleed) and preferably red blood cell infusion (leaving plasma).

Do not have too much vaginal prenatal examination when it is not needed. Wash hands and wear sterile gloves each time.

Early and timely detection of all manifestations of infection.

Treatment

For blood loss shock:

Treatment is the same as for traumatic and surgical shocks in general. But in the case of blood loss shock due to rupture of ectopic pregnancy, it is possible to take the blood back to the pregnant woman (return blood), to bring the hemoglobin, coagulation factors to the pregnant woman and must transfuse Soon.

Minimize the serum, especially saline serum when pregnant women are infected with pregnancy or heart disease.

Substances with large molecules can be used to replace blood such as fresh plasma, dry plasma, and albumin.

In conditions where there is no blood but serum must be used, it must be very careful, must rely on arterial blood pressure, central venous blood pressure, and especially oxygen under pressure. If intubation is required, give CPR and set PEEP from + 5 to + 10cm H2O. (PEEP: Positive End Expiratory Pressure, last positive pressure then exhale)

If the alkaline solution is infused to neutralize metabolic acidosis, it must be based on the formula and principles described in the previous section.

Must give patients sedatives and pain relievers according to the formula: valium 5 - 10mg + Fentanyl 0.05 - 0.1mg, intravenous injection or for artificial coagulation.

If the woman is late, the shock is severe:

Dextran infusion 40,000 to treat blood cell adhesion, with a dose of 500 - 1000ml, a rate of 30-50 mg/min, in parallel with blood transfusion or other solutions.

Cardiac support with Dopamin 5µg / kg / min or Isoprenalin 0.1 µg / kg / min.

If the woman has low urination, arterial blood and central venous blood have returned to normal, Lasix must be given from 20 - 200 mg/day, ensuring at least 60ml of urine per hour.

If there is a blood clotting disorder, it must be properly diagnosed to correct, however, before using specific drugs must:

Ensure good respiration. If necessary, add PEEP to bring the partial pressure of oxygen in the arterial blood to at least 100mmHg.

Must raise arterial blood pressure and keep at 100 - 120mmHg.

Must adjust the acid-base balance.

Without biochemical test facilities, dextran 40,000 should be infused and mainly fresh blood should be given. If still no results, use a mixture of Heparin and Epsilon Aminocaproic acid (EACA).

For septic shock:

Anti-bacterial infection:

Antibiotic: a broad-spectrum antibiotic, in combination and as an antibiotic for subsequent antibiotic adjustment.

There is a specific management attitude for each infected organ.

Anti-cardiomyopathy: the same as in general septic shock, but if the infection persists, the shock worsens, the uterus should be removed.

For thromboembolic shock caused by amniotic fluid:

This is the most difficult type of shock to treat. Treatment must be urgent and coordinated in many aspects.

Endotracheal intubation, do artificial respiration with continuous positive or non-alternating positive pressure, or add PEEP + 5 to + 10mmHg H2O, with an oxygen concentration of 60-80%, ensure a PaO2 from 100 - 120mmHg.

Cardiac support with Dopamine or Isoprenaline in parallel with the use of alpha-inhibitors Adrenecgic, to dilate the vasodilators and work to both reduce the post-cardiac burden and enlarge microcirculation, minimize the deficiency. oxygen in the tissues.

Heparin (even though patients undergoing surgery) must be given the first dose of 0.5 mg / kg, then every 4 or 6 hours, add 0.25 to 0.5 mg / kg or more (based on coagulation tests) to keep clotting time from 30 - 60 minutes, Howell time 2.30 - 3 minutes, Prothrombin rate 30% TEG (Emx / k = 5 - 10).

If, after giving heparin, the Vonkaulla test is still disturbed (less than 30 minutes), Epsilon Aminocaproic acid (EACA) can be given from 1- 2g, intravenously.

Must give Dextran 40,000 and fresh blood transfusion, the amount of Dextran does not exceed 1,500ml, the amount of fresh blood depends on the central venous blood pressure, arterial blood pressure, to the hematocrit (kept at 30-35%), fresh blood to prevent loss of blood fibrin.

Must give alkaline solutions of Natribicabonat (based on biochemical results). In the absence of biochemical tests, the following formula can be given: Vml (7.40% solution) = 10 x P (kg).

A catheter must be placed, monitor urine, for either the Mannitol 20% or Lasilix diuretics, so that 60ml of urine can be obtained every hour.

Fibrinogen 4g, if no result, 1 hour later, continue.