Anaesthetic Techniques in Pre-Eclampsia

Anaesthetic Techniques in Pre-Eclampsia

Regional Anesthesia

Regional techniques are superior to general anaesthesia in pre-eclamptic patients without cerebral symptoms for the following reasons:

• Avoids difficult/failed intubation. Patients with pre-eclampsia have increased oedema of the airway.
• They provide maximum analgesia, eliminating the risk of pain, apprehension and so on, which can raise the blood pressure and precipitate a convulsion.
• They have no direct effect on the patient's heart, lungs, kidneys or liver (if the spinal is given carefully). However, coagulation tests may be necessary before a spinal.

Pre-Operative Care

• Give IV fluids until the patient is considered to be in fluid balance, as evidenced by the vital signs of pulse, blood pressure and urine output. (However, in the eclamptic patient these vital signs may be affected by the underlying pathology and may not be as useful). A large bore cannula must be inserted.
• Monitor vital signs until the patient is brought to the operating room. Intra-arterial monitoring is very useful in severe pre-eclampsia.
• Check the following:

• Premedicate with ranitidine, metoclopramide and sodium citrate if available. Avoid prophylactic ephedrine.
• Make sure all the equipment necessary for a general anaesthetic is available, especially suction, oxygen, airways, endotracheal tubes, laryngoscopes.
• Follow the routine for a spinal anaesthetic for an obstetric patient, taking the usual precautions. Following spinal anaesthesia there may be a large drop in the patient's blood pressure which must be treated with small doses of ephedrine (3-6mg) and 250-500 ml boluses of Hartmann's solution.
• Be ready to resuscitate the baby (see the following notes on neo-natal resuscitation).

General Anaesthesia

General anaesthesia is the anaesthetic of choice in all patients with diminished level of consciousness e.g. those who have had eclamptic convulsions or are showing signs of increased cerebral irritability.

General anaesthesia may also be necessary in pre-eclamptic patients because of coagulation problems, maternal haemorrhage, or severe foetal distress.

General Anaesthesia Technique in Pre-Eclamptic and Eclamptic Patients

• Assess airway as there may be damage or swelling as a result of convulsions.
• Prepare all equipment for difficult intubation.
• Preoxygenate as for any emergency case.
• Induce anaesthesia with thiopentone (4-5mg/kg) or propofol 2-3mg/kg followed by suxamethonium (1-1.5mg/kg) as per rapid sequence induction with cricoid pressure. Ketamine is contra-indicated because it causes hypertension.
• To prevent the hypertensive response during laryngoscopy and intubation in severe pre-eclampsia give a generous dose of induction agent and use another agent, such as esmolol (0.5mg/kg over 15-30 secs) magnesium (loading dose as above), lignocaine (1.5mg/kg), fentanyl (1.5 micrograms/kg) or alfentanil (10 micrograms/kg). The neonate may need naloxone if opioids are used. Esmolol can also be used to prevent a hypertensive response at extubation.
• Maintain anaesthesia with small doses of a non-depolarising relaxant or suxamethonium infusion and a low concentration of volatile agent. An opioid can be given as soon as the baby is delivered.