Anaesthesia and Analgesia

Pain relief is often required during labour and is required during and after operative procedures. Methods of pain relief discussed below include analgesic drugs and methods of support during labour, local anaesthesia, general principles for using anaesthesia and analgesia and postoperative analgesia.

ANALGESIC DRUGS DURING LABOUR

• The perception of pain varies greatly with the woman’s emotional state. Supportive care during labour provides reassurance and decreases the perception of pain.

• If the woman is distressed by pain, allow her to walk around or assume any comfortable position. Encourage her companion to massage her back or sponge her face between contractions. Encourage the use of breathing techniques and allow the woman to take a warm bath or shower if she chooses. For most women, this is enough to cope with the pain of labour. If necessary, give:

- pethidine 1 mg/kg body weight (but not more than 100 mg) IM or IV slowly every 4 hours as needed or give morphine 0.1 mg/kg body weight IM;

- promethazine 25 mg IM or IV if vomiting occurs.

Barbiturates and sedatives should not be used to relieve anxiety in labour. 

DANGER

If pethidine or morphine is given to the mother, the baby may suffer from respiratory depression. Naloxone is the antidote.

Note: Do not administer naloxone to newborns whose mothers are suspected of having recently abused narcotic drugs.

If there are signs of respiratory depression in the newborn, begin resuscitation immediately:

- After vital signs have been established, give naloxone 0.1 mg/kg bodyweight IV to the newborn;

- If the infant has adequate peripheral circulation after successful resuscitation, naloxone can be given IM. Repeated doses may be required to prevent recurrent respiratory depression.

• If there are no signs of respiratory depression in the newborn, but pethidine or morphine was given within 4 hours of delivery, observe the baby expectantly for signs of respiratory depression and treat as above if they occur. 

PREMEDICATION WITH PROMETHAZINE AND DIAZEPAM

Premedication is required for procedures that last longer than 30 minutes. The dose must be adjusted to the weight and condition of the woman and to the condition of the fetus (when present). 

A popular combination is pethidine and diazepam:

• Give pethidine 1 mg/kg body weight (but not more than 100 mg) IM or IV slowly or give morphine 0.1 mg/kg body weight IM.

• Give diazepam in increments of 1 mg IV and wait at least 2 minutes before giving another increment. A safe and sufficient level of sedation has been achieved when the woman’s upper eye lid droops and just covers the edge of the pupil. Monitor the respiratory rate every minute. If the respiratory rate falls below 10 breaths per minute, stop administration of all sedative or analgesic drugs. 

Do not administer diazepam with pethidine in the same syringe, as the mixture forms a precipitate. Use separate syringes.

LOCAL ANAESTHESIA

Local anaesthesia (lignocaine with or without adrenaline) is used to infiltrate tissue and block the sensory nerves.

• Because a woman with local anaesthesia remains awake and alert during the procedure, it is especially important to ensure:

- counselling to increase cooperation and minimize her fears;

- good communication throughout the procedure as well as physical reassurance from the provider, if necessary;

- time and patience as local anaesthetics do not take effect immediately.

• The following conditions are required for the safe use of local anaesthesia:

- All members of the operating team must be knowledgeable and experienced in the use of local anaesthetics;

- Emergency drugs and equipment (suction, oxygen, resuscitation equipment) should be readily available, and should be in usable condition and all members of the operating team trained in their use.

LIGNOCAINE

Lignocaine preparations are usually 2% or 1% and require dilution before use (Box C-1). For most obstetric procedures, the preparation is diluted to 0.5%, which gives the maximum
effect with the least toxicity.

BOX C-1 Preparation of lignocaine 0.5% solution 

ADRENALINE

Adrenaline causes local vasoconstriction. Its use with lignocaine has the following advantages:

• less blood loss;

• longer effect of anaesthetic (usually 1-2 hours);

• less risk of toxicity because of slower absorption into the general circulation.

If the procedure requires a small surface to be anaesthetized or requires less than 40 mL of lignocaine, adrenaline is not necessary. For larger surfaces, however, especially when more than 40 mL is needed, adrenaline is required to reduce the absorption rate and thereby reduce toxicity.

The best concentration of adrenaline is 1:200 000 (5 mcg/mL). This gives maximum local effect with the least risk of toxicity from the adrenaline itself (Table C-3).

Note: It is critical to measure adrenaline carefully and accurately using a syringe such as a BCG or insulin syringe. Mixtures must be prepared observing strict infection prevention
practices (page C-17).

Table C-3 

Formulas for preparing 0.5% lignocaine solutions containing 1:200 000 adrenaline

Desired Amount of Local Anaesthetic Needed	Normal Saline	Lignocaine 2%	Adrenaline 1:1 000
20 mL	15 mL	5 mL	0.1 mL
40 mL	30 mL	10 mL	0.2 mL
100 mL	75 mL	25 mL	0.5 mL
200 mL	150 mL	50 mL	1.0 mL

COMPLICATIONS

Prevention of complications

All local anaesthetic drugs are potentially toxic. Major complications from local anaesthesia are, however, extremely rare (Table C-5). The best way to avoid complications is to prevent them:

• Avoid using concentrations of lignocaine stronger than 0.5%. 

• If more than 40 mL of the anaesthetic solution is to be used, add adrenaline to delay dispersion. Procedures that may require more than 40 mL of 0.5% lignocaine are caesarean section or repair of extensive perineal tears.

• Use the lowest effective dose.

• Observe the maximum safe dose. For an adult, this is 4 mg/kg body weight of lignocaine without adrenaline and 7 mg/kg body weight of lignocaine with adrenaline. The anaesthetic effect should last for at least 2 hours. Doses can be repeated if needed after 2 hours (Table C-4).

Table C-4

Maximum safe doses of local anaesthetic drugs 

• Inject slowly.

• Avoid accidental injection into a vessel. There are three ways of doing this:

- moving needle technique (preferred for tissue infiltration): the needle is constantly in motion while injecting; this makes it impossible for a substantial amount of solution to enter a vessel;

- plunger withdrawal technique (preferred for nerve block when considerable amounts are injected into one site): the syringe plunger is withdrawn before injecting; if blood appears, the needle is repositioned and attempted again;

- syringe withdrawal technique: the needle is inserted and the anaesthetic is injected as the syringe is being withdrawn.

DIAGNOSIS OF LIGNOCAINE ALLERGY AND TOXICITY

Table C-5 

Symptoms and signs of lignocaine allergy and toxicity 

MANAGEMENT OF LIGNOCAINE ALLERGY

• Give adrenaline 1:1 000, 0.5 mL IM, repeated every 10 minutes if necessary.

• In acute situations, give hydrocortisone 100 mg IV every hour.

• To prevent recurrence, give diphenhydramine 50 mg IM or IV slowly, then 50 mg by mouth every 6 hours.

• Treat bronchospasm with aminophylline 250 mg in normal saline 10 mL IV slowly.

• Laryngeal oedema may require immediate tracheostomy.

• For shock, begin standard shock management.

• Severe or recurrent signs may require corticosteroids (e.g. hydrocortisone IV 2 mg/kg body weight every 4 hours until condition improves). In chronic situations give prednisone 5 mg or prednisolone 10 mg by mouth every 6 hours until condition improves. 

MANAGEMENT OF LIGNOCAINE TOXICITY 

Symptoms and signs of toxicity (Table C-5) should alert the practitioner to immediately stop injecting and prepare to treat severe and life-threatening side effects. If symptoms and signs of mild toxicity are observed, wait a few minutes to see if the symptoms subside, check vital signs, talk to the woman and then continue the procedure, if
possible. 

CONVULSIONS

• Turn the woman to her left side, insert an airway and aspirate secretions.

• Give oxygen at 6-8 L per minute by mask or nasal cannulae.

• Give diazepam 1-5 mg IV in 1 mg increments. Repeat if convulsions recur.

Note: The use of diazepam to treat convulsions may cause respiratory depression.

RESPIRATORY ARREST

• If the woman is not breathing, assist ventilation using an Ambu bag and mask or via endotracheal tube; Give oxygen at 4-6 L per minute.

CARDIAC ARREST

• Hyperventilate with oxygen.

• Perform cardiac massage.

• If the woman has not yet delivered, immediately deliver the baby by caesarean section using general anaesthesia.

• Give adrenaline 1:10 000, 0.5 mL IV.

ADRENALINE TOXICITY 

• Systemic adrenaline toxicity results from excessive amounts or inadvertent IV administration and results in:

- restlessness;

- sweating;

- hypertension;

- cerebral haemorrhage;

- rapid heart rate;

- ventricular fibrillation.

• Local adrenaline toxicity occurs when the concentration is excessive and results in ischaemia at the infiltration site with poor healing.

GENERAL PRINCIPLES FOR ANAESTHESIA AND ANALESIA

The keys to pain management and comfort of the woman are:

- supportive attention from staff before, during and after a procedure (helps reduce anxiety and lessen pain);

- a provider who is comfortable working with women who are awake and who is trained to use instruments gently;

- the selection of an appropriate type and level of pain medication.

• Tips for performing procedures on women who are awake include:

- Explain each step of the procedure before performing it;

- Use adequate premedication in cases expected to last longer than 30 minutes;

- Give analgesics or sedatives at an appropriate time before the procedure (30 minutes before for IM and 60 minutes before for oral medication) so that maximum relief will be provided during the procedure;

- Use dilute solutions in adequate amounts;

- Check the level of anaesthesia by pinching the area with forceps. If the woman feels the pinch, wait 2 minutes and then retest.

- Wait a few seconds after performing each step or task for the woman to prepare for the next one;

- Move slowly, without jerky or quick motions;

- Handle tissue gently and avoid undue retraction, pulling or pressure;

- Use instruments with confidence;

- Avoid saying things like “this won’t hurt” when, in fact, it will hurt; or “I’m almost finished” when you are not;

- Talk with the woman throughout the procedure.

• The need for supplemental analgesic or sedative medications (by mouth, IM or IV) will depend on:

- the emotional state of the woman;

- the procedure to be performed (Table C-6);

- the anticipated length of the procedure;

- the skill of the provider and the assistance of the staff.

Table C-6  Analgesia and anaesthesia options

POSTOPERATIVE ANALGESIA

Adequate postoperative pain control is important. A woman who is in severe pain does not recover well.

Note: Avoid over sedation as this will limit mobility, which is important during the postoperative period.

Good postoperative pain control regimens include:

• non-narcotic mild analgesics such as paracetamol 500 mg by mouth as needed;

• narcotics such as pethidine 1 mg/kg body weight (but not more than 100 mg) IM or IV slowly or morphine 0.1 mg/kg bodyweight IM every 4 hours as needed; 

• combinations of lower doses of narcotics with paracetamol.

Note: If the woman is vomiting, narcotics may be combined with anti-emetics such as promethazine 25 mg IM or IV every 4 hours as needed.

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