[Crisis event] Sudden supine hypotension syndrome during perianesthesia

Sudden supine hypotension syndrome during peri-anesthesia period Contribution: Hang Bo Typesetting: Onion 1.
Occurrence and harm of sudden supine-position hypotension syndrome during peri-anesthesia period 1.
Syndrome of sudden supine-position hypotension syndrome during peri-anesthesia period Supine hypotensive syndrome (SHS) refers to the significant enlargement of the uterus in the third trimester of pregnancy.
When lying on the back, the heavy uterus presses against the spine, compresses the inferior vena cava, and obstructs the return of blood flow to the pelvic and inferior vena cava.
The sudden decrease in cardiac blood volume leads to a rapid decrease in cardiac output, resulting in a series of manifestations caused by insufficient heart and tissue supply
.

The main manifestations are: rapid drop in blood pressure, systolic blood pressure below 80mmHg or blood pressure drop >30mmHg, accompanied by fast and weak pulse, poor breathing, dizziness, chest tightness, nausea, sweating,
etc.

Supine hypotension syndrome in the peri-anesthesia period refers to the supine-position hypotension syndrome that appears within 1 to 2 days after the decision to undergo surgical anesthesia to the end of anesthesia
.

2.
Sudden supine hypotension syndrome in the peri-anesthesia period About 90% of puerperae in the third trimester will compress the inferior vena cava to varying degrees, and about 50% will have obvious symptoms of supine hypotension syndrome
.

The incidence of supine hypotension syndrome during cesarean section is 30%, and the incidence of hypotension during combined spinal-epidural anesthesia is more than 40%
.

Foreign studies have reported that in obstetric surgery, the incidence of supine hypotension syndrome after spinal anesthesia can be as high as 50% to 80%
.

Several situations of supine hypotension syndrome in pregnant and lying-in women are as follows: (1) During cesarean section, supine hypotension syndrome most often occurs 10 to 20 minutes after anesthesia and before delivery of the newborn, and spinal anesthesia is more common.
See (epidural block anesthesia, subarachnoid space block anesthesia, combined spinal-epidural block anesthesia), but less frequently in general anesthesia
.

Compared with epidural anesthesia, supine hypotensive syndrome occurs earlier and more frequently in subarachnoid block anesthesia
.

Since the pelvic sigmoid colon occupies the left side, the uterus will have different degrees of right rotation in the third trimester of pregnancy, and the inferior vena cava located on the right side of the spine has the characteristics of thin blood vessel wall and large lumen, and is easily compressed by the uterus
.

Pregnant women without anesthesia can compensate for pulse volume by increasing systemic resistance and accelerating heart rate, or by venous bypass, paraspinal veins, or the azygos system, and anesthesia attenuates these compensatory mechanisms
.

Studies have shown that timely monitoring and treatment of maternal hypotension is particularly important, and short-term hypotension will not increase maternal and fetal mortality
.

② The supine position is the conventional position during ultrasonography, and sometimes the uterus is pushed to the right in order to perform left abdominal exploration, which will aggravate the compression of the inferior vena cava and induce supine hypotension syndrome
.

Supine hypotension syndrome can also occur in pregnant women in the third trimester of pregnancy who spend too much time on their backs (while resting or sleeping)
.

(3) In the case of multiple pregnancy, polyhydramnios, macrosomia, etc.
, the enlarged uterus will increase the pressure in the abdominal cavity, thereby compressing the inferior vena cava and obstructing the return of blood.
Patients with poor cardiopulmonary function and preeclampsia are more prone to supine hypotension syndrome
.

3.
The symptoms of sudden supine hypotension syndrome during the peri-anesthesia period Hypotensive shock-related symptoms that occurred after pregnant women in the third trimester of pregnancy were supine for several minutes: dizziness, chest tightness, nausea, vomiting, whole body cold sweat, rapid pulse, systolic blood pressure decreased by 30mmHg or Drop to below 80mmHg; hypotension can cause acute fetal distress: increased fetal heart rate, increased fetal movement, followed by slow fetal heart rate and weakened fetal movement
.

The symptoms of supine hypotensive syndrome after anesthesia can be rapidly improved or completely resolved by changing position and delivery of the fetus, which can be differentiated from other causes of blood pressure drop after neuraxial anesthesia
.

4.
Hazards of sudden supine hypotension syndrome during peri-anesthesia period Supine hypotension syndrome can lead to fetal and neonatal asphyxia, endangering the lives of mothers and neonates
.

How to predict and prevent the occurrence of supine hypotension syndrome in peri-anesthesia period is a common problem faced by all anesthesiologists and obstetricians
.

(1) Hazards to the fetus or newborn: When the supine hypotension syndrome occurs during anesthesia, the return blood volume of the pregnant woman is reduced, the placental blood perfusion is reduced, and the fetus will experience fetal distress and neonatal asphyxia due to ischemia and hypoxia
.

In a state of hypoxia, in order to ensure the blood supply of vital organs, the cardiovascular and cerebrovascular vessels are expanded and other vessels are constricted
.

The constriction of the mesenteric vessels leads to gastrointestinal hypoxia, increased bowel motility, and relaxation of the anal sphincter, which ultimately leads to meconium contamination of the amniotic fluid
.

When fetal aerobic metabolism is inhibited, anaerobic glycolysis will be enhanced, and severe hypoxia for a long time will lead to the accumulation of acidic metabolites, causing internal environment disorders and acid-base balance disorders
.

(2) Harm to the mother: ① placental abruption
.

In supine hypotensive syndrome, increased intrauterine venous pressure leads to congestion or rupture of the decidual venous bed, and decidual hematoma can lead to partial or complete dissection of the placenta from the uterine wall.
Supine position occurs after anesthesia and before birth.
High incidence of hypotensive syndrome and placental abruption
.

②Acute left-sided heart failure: Due to the wrong diagnosis of supine hypotension syndrome in pregnant and lying-in women after anesthesia, no timely measures were taken to relieve the oppression of the uterus on the inferior vena cava, and it was mistaken for drug-induced hypotension and spinal canal resistance.
Insufficient blood return to the heart caused by stagnant vasodilation, application of vasopressor drugs and a large number of rapid infusions, resulting in increased circulating blood volume and peripheral vasoconstriction, and the sharp increase in return blood volume aggravates the afterload before the heart, resulting in acute pulmonary edema and left occurrence of heart failure
.

2.
Analysis of the causes of sudden supine hypotension syndrome during the peri-anesthesia period? 1.
Patient factors ① Increased blood volume: The blood volume increases at the 6th week of pregnancy and reaches a peak at 32 to 34 weeks of pregnancy
.

② Dilution of blood: It is manifested as a decrease in hemoglobin concentration, hematocrit and blood viscosity, and an acceleration of erythrocyte sedimentation rate
.

Reason: The increased blood volume is the sum of plasma volume and blood cells.
Plasma volume increases first and more, while red blood cells increase later and less
.

③ Increased interstitial fluid: hemodilution, decreased plasma albumin concentration, and increased intracapillary venous pressure lead to increased interstitial fluid production, and increased plasma estrogen, aldosterone, and deoxycorticosterone concentrations during pregnancy lead to sodium and water retention
.

④Increase of cardiac output: The cardiac output and heart rate increase from the 10th week of pregnancy, and reach the peak at the 28th week of pregnancy
.

⑤ Cephalopelvic asymmetry: When approaching the expected date of delivery, the connection of the fetus in the normal fetal position into the pelvis will reduce the compression of the inferior vena cava, while the abnormal fetal position (buttock, transverse, twin and giant fetal position) prevents the fetal head from entering the pelvis
.

2.
Surgical factors ① Patients with elective cesarean section have not yet experienced paroxysmal uterine contractions, the uterine blood flow is sufficient and the volume and weight are relatively large, which also has a greater impact on the blood return of the lower extremities and pelvis, so supine hypotension is prone to occur Syndrome; ② Pregnant women with emergency cesarean section often have regular uterine contractions, and paroxysmal uterine contractions can reduce uterine blood flow and relatively increase circulating blood volume; contract the uterus and lift it up along the birth axis, which can reduce the impact on the inferior vena cava.
The sympathetic nervousness of the puerperae entering the labor process is hypertensive, the breathing is deepened and accelerated, and the vascular tone is increased, and the negative pressure of the intrathoracic vein is conducive to venous return
.

3.
Anesthesia factors (1) Vasodilation: After spinal anesthesia, local anesthetics block sympathetic preganglionic fibers to dilate blood vessels within the blocking plane, resulting in decreased return blood volume and relatively insufficient blood volume
.

(2) Weakening of muscle strength: Local anesthetics and muscle relaxants can weaken the muscle strength of abdominal muscles and pelvic muscles, thereby weakening the supporting effect of muscles and ligaments around the uterus on the uterus, and aggravating the compression of the pregnant uterus on the inferior vena cava
.

(3) Diffusion of local anesthetic solution and high nerve block: In the third trimester of pregnancy, epidural vena cava distention and increased intra-abdominal pressure can increase the pressure of the epidural space, and pregnancy itself is sensitive to local anesthetics Increase, conventional doses of local anesthetics can lead to high block, the blood vessels in the block plane will expand and reduce the blood return to the heart, and the plane above T6 can also block the cardiac sympathetic nerve, manifested as decreased myocardial sympathetic tone, decreased contractility and heart rate.
Slow down, more prone to supine hypotensive syndrome
.

3.
Coping strategies for sudden supine hypotension syndrome during peri-anesthesia period Manifested as blood pressure drop (systolic blood pressure drops below 80mmHg or blood pressure drop >30mmHg), accompanied by fast and weak pulse, poor breathing, dizziness, chest tightness, nausea and sweating, etc.
; Improvement or complete disappearance can be diagnosed as supine hypotension syndrome
.

2.
Monitoring (1) Supine stress test: measure the blood pressure and heart rate of the puerperae in the left lateral position and supine position respectively.
If the heart rate of the puerperae in the supine position is measured twice in a row, the increase is faster than the basic value in the lateral position by 10 times.
/min, or the systolic blood pressure in the supine position measured twice in a row is more than 15mmHg lower than the baseline value in the lateral position, or the mother has symptoms such as dizziness, chest tightness, nausea, vomiting, cold sweat all over the body, and rapid pulse, and one of them is satisfied.
can be diagnosed
.

The supine stress test had a sensitivity of 69% and a specificity of 92% in predicting supine hypotension syndrome after spinal anesthesia
.

(2) Hanss et al.
have proved that heart rate variability can reflect autonomic balance.
The basic low frequency and high frequency ratio (LF/HF) was divided into two groups.
The results showed that the incidence of supine hypotension syndrome after spinal anesthesia in the high LF/HF group Significantly larger than the low LF/HF group
.

(3) Advanced maternal (N35 years old), obesity (BMI>29~35), macrosomia (weight>4000g) are all risk factors affecting supine hypotension syndrome after spinal anesthesia
.

(4) Young-Tae Jeon and other studies found that the incidence of hypotension was 41% when the change in mean arterial pressure before anesthesia caused the change in mean arterial pressure above 11mmHg
.

3.
Treatment Before anesthesia, after anesthesia or during the operation, closely observe whether the pregnant woman has the early manifestations of supine hypotension syndrome: palpitations, shortness of breath, chest tightness,
etc.

In the left lateral position, the intra-abdominal pressure is significantly lower than that in the supine position.
After the anesthesia is completed, take the supine position, tilt the operating bed on the left side or raise the right buttock by 15° to 30°, and push the uterus to the left side of the abdominal cavity to facilitate amniotic fluid flow.
To the left can reduce the incidence of supine hypotensive syndrome after anesthesia
.

During the peri-anesthesia period, once the symptoms of hypotension syndrome in the supine position occur, immediate measures should be taken and help is called for: (1) keep the airway unobstructed, and use a mask to inhale high-flow oxygen; (2) keep the left lateral decubitus position or push the uterus to the left.
The uterus of pregnant and lying-in women will be left-rotated.
If the above measures are not effective, consider adjusting the operating table in the opposite direction: (3) Remove vomit in time to prevent aspiration; (4) Select appropriate vasoactive drugs according to the degree of blood pressure drop and heart rate increase to maintain Stable hemodynamics; ⑤ Try to shorten the operation time and make preparations for rescuing the newborn
.

4.
Thoughts on sudden supine hypotension syndrome in peri-anesthesia Language, more important than understanding the disease is to understand the patient
.

" It can be seen that good communication is an important prerequisite for ensuring a harmonious relationship between doctors and patients, and it is also the basis for improving the quality of medical services
.

The "bio-psycho-social" medical model also requires doctors to have good doctor-patient communication skills
.

As one of the non-technical contents of anesthesiologists, doctor-patient communication plays a pivotal role in maintaining a good doctor-patient relationship, reducing doctor-patient conflicts, and reducing the incidence of medical disputes
.

Anesthesiologists are a high-risk profession.
All operations related to anesthesia are invasive.
Improper use of anesthesia drugs will lead to fatal consequences.
It reflects the importance of the work of anesthesiologists
.

Faced with today's complex medical environment, anesthesiologists should pay more attention to improving doctor-patient communication skills, thereby reducing doctor-patient conflicts and medical disputes
.

①Besides paying attention to the general situation of pregnant women before surgery, you should also ask about your body position preference during pregnancy and whether you feel uncomfortable after changing the body position; ②Explain the operation method, anesthesia method, intraoperative cooperation and other related matters, so as to relieve psychological pressure and prevent excessive tension, which is effective and effective.
Nursing intervention can shorten the time of supine hypotensive syndrome; ③For high-risk women with supine hypotensive syndrome (uterine fibroids complicated with pregnancy, macrosomia, placenta previa, cephalopelvic disproportion, and transverse breech position), before surgery Have first aid supplies ready
.

2.
Routine oxygen inhalation and preventive infusion Routine oxygen inhalation after anesthesia to increase the oxygen partial pressure of the mother and the fetus, shorten the operation time as much as possible after the occurrence of supine hypotension syndrome, and prepare for neonatal rescue
.

(1) Infusion site: In the third trimester of pregnancy, the uterus compresses the inferior vena cava, the venous blood return of the lower extremity is slow, and the intravascular pressure is higher than that of the upper extremity, and spinal anesthesia will cause vasodilation of the lower extremity, while the upper extremity veins are not compressed or anesthetized.
Due to the influence of the block, the smooth return of the upper limb infusion is conducive to speeding up the infusion and treatment.
Once the supine hypotension syndrome occurs, the effective circulating blood volume can be replenished in time.
Therefore, the upper limb vein should be selected as the infusion site
.

(2) Types of fluids: Appropriate infusion can reduce and prevent the occurrence of supine hypotensive syndrome, and colloid and hypertonic crystalloids are more effective than isotonic crystalloids
.

About 75% of the crystalloid will be transferred to the interstitial space, and the volume expansion effect can only be maintained for 15 minutes; while the colloid remains in the blood vessel for a long time, and the cardiac output and tissue perfusion can be effectively improved by increasing the intravascular colloid osmotic pressure
.

3.
Anesthesia methods After spinal anesthesia and during surgery, keeping awake parturients is helpful for the detection of supine hypotension syndrome
.

Compared with general anesthesia, intraspinal anesthesia is more commonly used for cesarean section
.

Spinal anesthesia includes continuous epidural block anesthesia, subarachnoid space block anesthesia, and combined spinal-epidural block anesthesia
.

Epidural space stenosis at the end of pregnancy, the use of spinal anesthesia should reduce the amount of local anesthetic
.

Continuous epidural block: administer the test dose first and then divide the dose, monitor the block level to prevent extensive epidural block
.

Subarachnoid block has the advantages of fast onset, good analgesic effect, and perfect muscle relaxation, but it is prone to supine hypotension syndrome
.

V.
Sharing of typical cases of sudden supine hypotension syndrome during the peri-anesthesia period
.

Weight gain during pregnancy is 20kg
.

Admission examination: systemic edema (+++), urine protein (+), abdominal circumference 118cm, palace height 42cm, slightly larger than the gestational age, electrocardiogram: abnormal ST segment T wave (lower lateral wall), abnormal electrocardiogram
.

The preoperative diagnosis was: pregnancy 38+5w G4P1 ROA expecting labor
.

Entering the operating room: blood pressure: 125/70mmHg, heart rate 105 beats/min, epidural puncture was performed in the L1-2 space, the puncture was successful, no cerebrospinal fluid was withdrawn, 5ml of 2% lidocaine was slowly pushed in, and a 4cm catheter was placed in the head.
, put the patient in the supine position, the patient was normal after 5 minutes, and 10ml of 2% lidocaine was pushed into the epidural catheter again.
After 6 minutes, the patient felt dizzy and nauseated.
Blood pressure: 75/35mmHg, heart rate 114 beats/ 20 mg of ephedrine was administered intravenously immediately, but the effect was not good.
Then the patient developed agitation, complained of general discomfort and difficulty in breathing.
Immediately, the mask was pressurized to give oxygen, and 20 mg of ephedrine was injected intravenously again, but the patient was still restless and had difficulty breathing.
Aggravated, cyanotic lips
.

Blood pressure measurement: 56/25mmHg, heart rate 118 beats/min, clear breath sounds in both lungs, no dry or wet rales
.

Immediately, the operating table was tilted to the left and the uterus was moved, but the blood pressure was undetectable, and the heart rate was 128 beats/min.
The patient was still irritable, the cyanosis was further aggravated, and the consciousness gradually disappeared.
Immediately, a rapid intravenous infusion of 60 mg of dopamine and 10 mg of dexamethasone was administered intravenously.
, the blood pressure quickly rose to 120/60mmHg, and the consciousness quickly recovered.
This process took about 12 minutes
.

At this time, the anesthesia level was measured below T8
.

Keep pushing the uterus, the operation ended smoothly, and the mother and child were safe
.

2.
1 case of placental abruption caused by supine hypotension syndrome A 26-year-old patient was admitted to hospital at 10 am due to 40+3 weeks of menopause, G1P0, LSA, breech presentation (mixed breech presentation)
.

Physical examination on admission: body temperature 37°C, pulse 80 beats/min, respiration 19 beats/min, blood pressure 110/70mmHg
.

Obstetric examination: palace height 33cm, abdominal circumference 100cm, breech presentation, fetal heart rate 136 beats/min
.

At 2:30 pm on the day of admission, no uterine contractions, no rupture of membranes, fetal heart rate 144 beats/min, NST response type score 10 points, fetal weight is about 3600g, considering the mixed breech position and the large fetal weight are the surgical indicators.
Signs, cesarean section
.

The patient entered the operating room at 3:30 p.
m.
, conscious and in good spirits, blood pressure 115/70 mmHg, heart rate 80 beats/min, continuous epidural puncture and catheterization were all smooth, changed to supine position, fetal heart rate 140 beats/min, At 3:45 p.
m.
, the test volume of local anesthetic 2% lidocaine plus 3ml of 1:200,000 U epinephrine mixture was injected.
After 10 seconds of injection, the patient was restless, nauseated, palpable, and blood pressure continued to drop.
At 3:51:30 p.
m.
Second blood pressure was as low as 60/30 mmHg, heart rate was as slow as 42 beats/min, and the plane of acupuncture anesthesia did not appear.
The possibility of anesthesia accident and allergy was excluded, and supine hypotension syndrome was considered
.

Adjust the operating table to the left tilt of 30°, push the uterus to the upper left with both hands, inhale oxygen through the mask, inject 30 mg of ephedrine intravenously, but no improvement is seen.
The surgeon immediately started the operation under local anesthesia.
The skin was incised at 3:58:30 pm, and the abdomen was opened at 4:1:20 pm.
Bloody amniotic fluid was seen during the incision of the uterus.
Lu delivered a baby boy weighing 3800g.
Apgar score was 5 points in 1 minute and 9 points in 10 minutes after rescue.
He was transferred to pediatric treatment
.

After the fetus was delivered, the bloody amniotic fluid gushed out, the color was red, the amount was about 1600ml, 20U of oxytocin was injected into the uterus, and the placenta was quickly delivered.
The placenta was checked for 1/3 of the abruption surface, but there was no blood clot impression, indicating that the placental abruption was very short.
(within 10 minutes)
.

After the fetus was delivered, the patient's blood pressure rose to 120/70mmHg after rehydration.
The estimated intraoperative blood loss was about 1200ml, and the rehydration was 2000ml
.

Postoperative diagnosis: ① intrauterine pregnancy 40+3 weeks, G1P0, LSA delivery; ② breech foot presentation; ③ placental abruption; ④ postpartum hemorrhage; ⑤ supine hypotension syndrome
.

After the operation, the patients were treated with fluid, blood, and anti-infection
.

The blood pressure was maintained at 110~120/60~70mmHg, the sutures were removed on the 6th day, and the mother and child were discharged safely on the 7th day
.