Anesthesia for cesarean section

Anesthesia for cesarean section may vary. The anesthesiologist should remember and inform the obstetrician and neonatologist if more than 8 minutes pass from the skin incision to the extraction of the fetus and more than 3 minutes from the uterine incision to its extraction. Regardless of the technique, there is a high risk of developing intrauterine hypoxia and acidosis in the fetus/newborn.

Advantages of RAA:

• minimal risk of aspiration of gastric contents into the trachea;
• the risk of failure during tracheal intubation appears only when complications develop;
• presence at childbirth, early contact with the child;
• there is no risk of unexpected exit from the state of anesthesia.

Disadvantages of RAA:

• complete absence or insufficient effect is possible;
• unexpectedly high or complete block;
• headache after spinal puncture;
• neurological complications;
• toxicity of local anesthetics when administered epidurally.

Advantages of endotracheal anesthesia for cesarean section:

• rapid advance;
• provides quick access to all areas of the body for surgical and anesthetic interventions;
• allows you to control gas exchange and hemodynamics;
• quickly relieves cramps.

Disadvantages of endotracheal anesthesia for cesarean section:

• risk of unsuccessful tracheal intubation;
• risk of aspiration of stomach contents into the trachea;
• risk of intraoperative recovery of consciousness;
• risk of CNS depression in the newborn;
• development of abnormal reactions to the drugs used is possible.

The pregnant woman is placed on the table with a cushion under the right/left buttock. The risk of developing arterial hypotension when using regional methods is higher than when using them for analgesia during labor. When choosing these methods, it is necessary to preventively administer 1200-1500 ml of crystalloids and/or starches and prepare an ephedrine solution:

Hydroxyethyl starch, 6% solution, intravenous

500 ml,

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Crystalloids intravenously 800 ml, or Crystalloids intravenously 1200-1500 ml.

[ 1 ], [ 2 ], [ 3 ], [ 4 ]

Epidural anesthesia for cesarean section

In case of planned caesarean section it is the method of choice. It is used:

Bupivacaine, 0.5% solution, epidural 15-25 ml, or Lidocaine, 1.5-2% solution, epidural 15-25 ml. If the test dose does not reveal incorrect catheter position, MA is administered fractionally, 5 ml at a time, up to a total dose of 15-25 ml. In pregnant women with sympathicotonia, adding clonidine to the MA solution deepens and prolongs anesthesia during cesarean section without adversely affecting the fetus and newborn:

Clonidine epidurally 100-200 mcg, as indicated (usually in divided doses). If pain occurs, MA is administered again in divided doses of 5 ml until the effect is achieved. Epidural administration of morphine at the end of the operation provides adequate postoperative pain relief for 24 hours. An alternative is continuous epidural infusion of fentanyl or sufentanil:

Morphine epidurally 3-5 mg, or Sufentanil epidurally 10-20 mcg/h, the duration of administration is determined by clinical appropriateness, or Fentanyl epidurally 50-75 mcg/h, the frequency of administration is determined by clinical appropriateness.

[ 5 ], [ 6 ], [ 7 ], [ 8 ]

Spinal anesthesia for cesarean section

Fast and reliable anesthesia for cesarean section in the absence of contraindications. Used:

Bupivacaine, 0.5% solution (hyperbaric solution), subarachnoid 7-15 mg, or Lidocaine, 5% solution (hyperbaric solution), subarachnoid 60-90 mg. The use of thin (22 G and thinner) pencil-type spinal needles (Whitacre or Sprott) reduces the risk of post-puncture headache. Even with the Th4 blockade level, a pregnant woman may experience discomfort during uterine traction. Adding opioids in small doses to MA (fentanyl 10-25 mcg) reduces the intensity of these sensations without adversely affecting the condition of the newborn. There are data on the use of clonidine (50-100 mcg) in combination with bupivacaine in SA.

Long-term spinal anesthesia for cesarean section is advisable in case of unintentional puncture of the dura mater during catheterization of the epidural space. The catheter is inserted 2-2.5 cm into the subarachnoid space and fixed, after which it can be used for drug infusion.

General anesthesia for cesarean section

The method of choice for planned and emergency cesarean sections when RAA is contraindicated, significant blood loss is expected or has already occurred (placental abruption and previa, uterine rupture, etc.). Premedication:

Diphenhydramine IM 0.14 mg/kg (in emergency situations - IV before induction) 30-40 minutes before the planned operation

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Atropine IV 0.01 mg/kg, on the operating table or Metocinium iodide IV 0.01 mg/kg, on the operating table

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Ketoprofen IV 100 mg, 30-40 minutes before the planned operation or Ketorolac IV 0.5 mg/kg, 30-40 minutes before the planned operation. In a planned situation, prescribe: Ranitidine orally 150 mg, 6-12 hours and 1-3 hours before induction or Cimetidine orally 400 mg or intramuscularly 300 mg, 6-12 hours and 1-3 hours before induction

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Metoclopramide IV 10 mg, 1.5 hours before induction

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Sodium citrate, 0.3M solution, orally 30 ml, 30 minutes before induction. The most effective use of omeprazole:

Omeprazole orally 40 mg, at night and in the morning on the day of surgery. In an emergency, prescribe:

Ranitidine IV 50 mg, or Cimetidine IV 200 mg,

Metoclopramide IV 10 mg,

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Sodium citrate, 0.3 M solution, orally 30 ml, 30 minutes before induction. An alternative is the administration of omeprazole:

Omeprazole IV 40 mg.

There is no consensus on how to empty the stomach. The author likes the following method

If 3-4 hours have passed since the meal and the risk of difficult tracheal intubation is low, the above-mentioned prophylaxis is sufficient. If less than 3-4 hours have passed since the meal and the risk of difficult intubation is high, it is necessary to compare the significance of the consequences of hypercatecholaminemia and the "triggering" of the gag reflex in response to the introduction of a gastric tube with the risk of developing aspiration of gastric contents into the trachea if its introduction is refused and your own skills in tracheal intubation in pregnant women. The conclusion will suggest the optimal solution to the problem. A nasogastric tube is unreliable as a means of removing gastric contents (but if used, the diameter should be maximum), its presence in the stomach during induction increases the risk of regurgitation, therefore it is better to remove the tube before induction. It should not be assumed that the stomach is completely emptied by vomiting and/or the introduction of the tube, therefore the above-mentioned prophylaxis should always be carried out.

Then you need to:

• insert a large diameter catheter (1.7 mm) into a vein (peripheral and/or central);
• insert a catheter into the bladder (the obstetrician decides if there are no direct indications);
• conduct standard monitoring;
• lay the pregnant woman on her back and move the uterus to the left/right by placing a cushion under the right/left buttock;
• perform preoxygenation with 100% oxygen for 3 minutes (in an emergency, mechanical ventilation is started only after tracheal intubation). If the anesthesiologist is preparing for difficult tracheal intubation (difficulty assessment according to SR Mallampati), the risk of failure during its implementation is significantly reduced: a conscious algorithm allows to significantly reduce the time for finding solutions, and the availability (readiness) of the necessary equipment - the time for their implementation. The life of the woman in labor has priority over delivery, but one should also remember the high responsibility for the successful birth of a new life.

The necessary equipment includes (the list should be reviewed regularly):

• second laryngoscope;
• set of endotracheal tubes;
• combination tube with esophageal obturator;
• set of oral airways; o nasal airways;
• laryngeal masks (size 3 and 4) to temporarily maintain adequate ventilation in a critical situation;
• conicotomy kit;
• Dilatational tracheostomy kit; o fiber bronchoscope;
• high professional level of application of all of the above according to a conscious algorithm. The described preoperative preparation is advisable for all pregnant women whose method of delivery is cesarean section, since in case of failure in performing regional methods, the alternative will be endotracheal anesthesia for cesarean section, but without time for preparation.

Induced anesthesia for cesarean section

Ketamine IV 1-1.2 mg/kg, (scheme 1) or Hexobarbital IV 4-5 mg/kg, single dose (scheme 2) or Ketamine IV 0.5-0.6 mg/kg,

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Hexobarbital IV 2 mg/kg (scheme 3) or Clonidine IV 2-3.5 mcg/kg,

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Ketamine IV 0.8-1 mg/kg (scheme 4) or Clonidine IV 2-3.5 mcg/kg,

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Hexobarbital intravenously 3-3.5 mg/kg, once (scheme 5).

If there are no contraindications, induced anesthesia for cesarean section is performed with intravenous ketamine or hexobarbital (or their combination, respectively). In case of bleeding, there is no alternative to ketamine, but it should be remembered that sometimes in pregnant women with severe hemorrhagic shock, circulatory failure, LS can reduce the contractility of the myocardium due to sympathetic hyperstimulation.

In pregnant women with initial sympathicotonia and/or gestosis, depending on the initial blood pressure level, schemes 4 or 5 are used with additional administration of tranexamic acid, which can also be included in schemes 1-3 if a traumatic operation with significant blood loss is expected:

Tranexamic acid intravenously 8-9 mg/kg, once.

Muscle relaxation:

Suxamethonium chloride intravenously 1.5 mg/kg, single dose.

After induction, anesthesia for cesarean section is performed with suxamethonium chloride (it is desirable that the total dose before fetal extraction does not exceed 180-200 mg), tracheal intubation is performed using the Sellick maneuver, and artificial ventilation is switched to. The only drug that provides rapid muscle relaxation is suxamethonium chloride. Suxamethonium chloride is poorly soluble in fats and has a high degree of ionization. Due to this, it passes through the placenta in very small quantities. A single administration of the drug to the mother at a dose of 1 mg/kg is safe for the fetus, but large doses or repeated administrations at short intervals can affect neuromuscular transmission in the newborn. In addition, if the mother and fetus are homozygous for atypical plasma pseudocholinesterase, then, despite the administration of minimal doses of suxamethonium chloride to the mother, its concentration in the blood of the fetus may be sufficient to cause severe depression of neuromuscular conduction.

In case of induction of anesthesia for cesarean section according to schemes 1, 2 or 3, anesthesia for cesarean section is performed using:

Dinitrogen oxide with oxygen by inhalation (1:1 or 2:1). After the fetus is extracted, the following is administered:

Fentanyl IV 3-4 mcg/kg (0.2-0.3 mg), single dose, then after 15-20 min I IV 1.4 mcg/kg, single dose

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Diazepam IV 0.14-0.2 mg/kg (10-15 mg), once as indicated

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Droperidol intravenously 0.035-0.07 mg/kg, single dose.

In case of induction of anesthesia according to schemes 4 and 5, anesthesia for cesarean section is performed using:

Dinitrogen oxide with oxygen by inhalation (1:1 or 2:1). After the fetus is extracted, the following is administered: Fentanyl intravenously 1.4-2 mcg/kg, once, then after 25-30 minutes intravenously 0.7-0.8 mcg/kg, once.

+

Diazepam intravenously 0.07-0.14 mg/kg, single dose.

In pregnant women with initial sympathicotonia and/or gestosis, depending on the initial blood pressure level, schemes 4 or 5 are used with additional administration of tranexamic acid at the stage of uterine incision, which is also included in schemes 1-3 if the operation is traumatic and may be accompanied by significant blood loss:

Tranexamic acid intravenously 5-6 mg/kg, once.

Until the fetus is extracted, artificial ventilation is continued with dinitrogen oxide and oxygen in a 1:1 ratio; muscle relaxation is maintained with suxamethonium chloride or by administering short-acting non-depolarizing muscle relaxants (mivacurium chloride).

Hyperventilation should be avoided due to its negative effect on uterine blood flow. After the fetus is extracted, an antibiotic is administered (prevention of intraoperative infection - agree with the obstetrician). After separation and removal of the placenta - methylergometrine (if there are no contraindications) and/or switch to oxytocin infusion (agree with the obstetrician): Methylergometrine intravenously 1 ml, once or Oxytocin intravenously 5-10 U, once, then drip 5-10 U.

In case of uterine hypotension, calcium preparations are additionally administered:

Calcium gluconate, 10% solution, intravenous 5-10 ml, once or Calcium chloride, 10% solution, intravenous 5-10 ml, once.

After clamping the umbilical cord, continue artificial ventilation with dinitrogen oxide and oxygen in a ratio of 1:1 or 2:1 and switch to NLA or ataralgesia. Fentanyl and diazepam or midazolam are administered in an equivalent dose.

It is necessary to remember that diazepam has an enterohepatic cycle, which provokes the onset of resedation, coinciding in time with the appearance of active metabolites. Within a few hours, such a rebound phenomenon can cause not only resedation, but also respiratory failure. Fentanyl is administered again after 15-20 minutes at a dose of -1.4 mcg/kg (0.1 mg), stopping the administration 30-40 minutes before the end of the operation (before immersion of the uterus into the abdominal cavity). Droperidol is used if indicated. For pregnant women with initial sympathicotonia and/or gestosis (see algorithm), it is recommended to include central alpha-adrenergic agonists (clonidine and its analogues - dexamethasone, etc.) and/or protease inhibitors (tranexamic acid) in the anesthesia regimen. Anesthesia for cesarean section is performed using clonidine (schemes 4 and 5) identical to the above. Clonidine is administered immediately after the pregnant woman is admitted to the operating room (a thorough assessment of the volemic status is necessary, and correction if necessary; the drug in this situation has only an antihypertensive effect, while maintaining autoregulation of systemic blood flow).

Within 5 minutes, the blood pressure, heart rate, and level of consciousness are assessed, and based on the heart rate data, the required dose of atropine (methocinium iodide) is determined and administered. Due to the analgesic, sedative, and vegetative-stabilizing properties of clonidine, the body's sensitivity to anesthetics, anxiolytics, analgesics, neuroleptics, and muscle relaxants increases, the doses of which are reduced by 1/3 compared to standard doses. Induction is performed with ketamine or hexenal.

After the fetus is extracted, fentanyl and diazepam (or midazolam) are administered. Fentanyl is administered again after 25-30 minutes, depending on the trauma and duration of the operation.

Compared with standard anesthesia, cesarean section provides more stable hemodynamic parameters at the intra- and postoperative stages: after consciousness is restored, there is no pain, muscle tremors, or microcirculation disorders.

Anesthesia for cesarean section using tranexamic acid is identical to the above. In addition to the above option, there is another option for using tranexamic acid - 7-8 mg / kg before induction and in the same dose intravenously by drip every hour of surgery. The use of tranexamic acid allows you to reduce the doses of narcotic analgesics, anxiolytics and muscle relaxants, and therefore the frequency of side effects and complications, is accompanied by less bleeding and blood loss (by 20-30%).

In the absence of contraindications in pregnant women with pronounced sympathicotonia and severe gestosis during cesarean section, the use of combined (endotracheal and regional) anesthesia is indicated during cesarean section, in which analgesia and NVT are represented mainly by the regional method, and the remaining components are endotracheal, which together is called multicomponent anesthesia balanced at the level of subcomponents and routes of their administration.