Q about using pethidine during labour...

[BellyBelly]

What are the disadvantages of using pethidine for pain relief in labour?

Pethidine may not provide adequate pain relief for some women. Nausea and vomiting are common, a medication may be mixed with the pethidine to help reduce these effects. Some women report feeling drowsy and confused. The effects pethidine has on perception may make the contractions difficult to deal with. Other potential side effects for the woman in labour include difficulty passing urine, dry mouth, hallucinations, respiratory depression, low blood pressure and allergic reaction .

There are no advantages to the baby if the mother has pethidine. Pethidine is known to cross the placenta and is present in breastmilk. The major problem for the baby is that pethidine can cause breathing difficulties after birth due to its depressive effect on the baby’s respiratory centre. These effects are at the worse if the baby is born one to three hours after an injection of pethidine has been given. This is the reason that pethidine is ideally avoided when the birth is perceived to be close. An antidote can be given to the baby to reverse the effects of pethidine, however the effects of the antidote only last a short time and when they wear off the baby may re-experience breathing problems. Baby’s are more likely to have jaundice if their mothers have pethidine. Pethidine effects the baby’s sucking reflex and can cause breastfeeding difficulties for the first few days. Baby’s may require special care or neonatal intensive care from the effects of pethidine, resulting in separation of mother and baby.

This is from Birth International (Andrea Robertson's site)

Narcotic (Opiate) Drugs
Pethidine (demerol), Morphine, Heroin (diamorphine)

This group of drugs have similar properties and effects. They are usually given as a sedatives in labour. They are not pain killing drugs, but may ease the pain indirectly as the mother becomes sedated.

Pethidine (demerol) is the most widely used, so it will be used as an example. Less is known about the effects of the other opiates on women and newborns because less research has been conducted to test their efficacy and safety.

Dosage:
The drug is supplied in prepared doses and 100mg is the commonest size, although smaller doses may be available. It should be given according to body weight. Pethidine is usually prescribed by a doctor but given by the midwife, and if a smaller dose is requested by the mother, the midwife will have to consult the doctor before the dose can be varied. 75 mg would be required for an average man when being used for post-operative pain.

It may be possible to request a smaller dose to begin, on the basis that if this is not enough, more can be administered later. Once in the system it is impossible to remove the drug except by waiting for the woman's body to eliminate the drug through her liver and kidneys (about 6 hours in a pregnant woman).

Time lag:
10-20 minutes

Duration:
2-3 hours

Route administered:
Usually by injection into the thigh or buttock. Sometimes via a drip, if one is in place.

When given:
During first stage, once labour is established. Should not be given if the birth is expected within 2 hours. Sometimes given for pain relief following Caesarean section.

Effects on the mother:
Advantages:
1. Sedates.
2. Has a secondary effect as a muscle relaxant, which ay lessen pain and reduce muscle tension, allowing faster dilatation.
3. May reduce pain.

Disadvantages:
1. Does not relieve the pain directly.
2. Creates a high', with feelings of floating and light-headedness that makes concentration difficult.
3. Some people are so sedated that drowsiness makes it difficult to cope with contractions.
4. Nausea, vomiting and dizziness are all common side-effects. An additional drug to counteract these effects is usually mixed with the pethidine before injection.
5. Depresses the mother's breathing rate, which can reduce oxygenation of the blood.
6. If the sedation results in a more rapid rate of dilatation than was expected, the baby may be born with more of the drug in its system than was intended.
7. Opiate drugs cause delayed emptying of the stomach, increasing the risks of aspiration syndrome, a serious complication, if a general anaesthetic becomes necessary.

Effects on the baby
Advantages: None.

Disadvantages:
1. Pethidine crosses the placental barrier and depresses the baby's respiratory centre. This will cause breathing difficulties for the baby if it is born when the drug is at a maximum dosage in its system (between 1 and 3 hours after the injection).
2. An antidote to counteract the depressive effects on the baby can be given but this gives only temporary relief and the baby may still suffer breathing difficulties when the antidote wears off after a few hours.
3. Increased likelihood of jaundice as the baby's immature system works to eliminate the drug (and its antidote, if given). It may take 4-5 days for the baby to eliminate most of this drug from its system.
4. Separation of mother and baby if these problems are severe.
5. Difficulties establishing breastfeeding due to a depressed suckling reflex.
6. Research has demonstrated a potential link between exposure of some babies to pethidine during labour and their later development of an addiction to opiate drugs as teenagers.