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Analgesia means the relief of pain. Drugs used to relieve pain are called analgesics. Analgesics must not be confused with sedatives which do not relieve pain but only make the patient drowsy.
Anaesthesia means the loss of all sensation, including pain. Local anaesthesia causes the loss of all sensation in that region of the body. With general anaesthesia the patient loses consciousness.
Pain in labour is caused by:
The amount of pain experienced by patients in labour is very variable. Some patients have little pain, while others have severe pain, even during early labour.
Anxiety, fear and uncertainty lower the pain threshold. This is particularly noticeable in primigravida patients, especially if they are very young. Pain increases the patient’s anxiety, which in turn reduces her ability to tolerate pain.
A patient should be prepared for her labour during the antenatal period. Primigravidas must be told in simple terms what is going to happen during labour. Relaxation exercises and breathing methods can help patients prepare for labour, and should be taught as part of antenatal care.
During labour, particularly during the latent phase and early in the active phase of the first stage, patients may be encouraged to walk around and not spend all the time in bed in the labour ward. This reduces the amount of pain experienced during contractions. In addition, contractions will be more effective, resulting in labour progressing faster.
A calm, considerate and caring attitude from those who are attending the patient in labour is important. Thorough but gentle clinical examinations, rubbing the patient’s back and talking to her all do much to relieve the stress of labour and to some extent, the pain.
Most patients find it helpful to have someone with them during labour. A lay person or doula can fulfill this role perfectly well. A patient should be encouraged to have her partner, a family member, or someone else that she knows well to stay with her during labour.
Antenatal preparation and emotional support are important in reducing anxiety and pain during labour.
The nerve impulses that come from the lower back travel to the same spinal segments as the nerves from the uterus and cervix. The nerve impulses from the lower back, therefore partially block those from the uterus and cervix. As a result, the pain of contractions is experienced as less painful by the patient if her lower back is rubbed.
The relief of pain is very important and must receive careful attention when a patient is cared for during labour.
No. Some patients have little pain in labour and, therefore, may not need an analgesic. Other patients feel that they are able to tolerate the pain of uterine contractions, e.g. by concentrating on their breathing, and choose not to have analgesia. It is important to consider the patient’s wishes when deciding whether or not to give analgesia. However, most patients do need analgesia during labour.
Pethidine. This drug is a powerful analgesic but commonly causes nausea and vomiting as a side effect. Pethidine also produces some sedation.
Promethazine (Phenergan) or hydroxyzine (Aterax). They combine well with pethidine for three reasons:
The dose of promethazine is 25 mg and hydroxyzine is 100 mg, irrespective of the amount of pethidine given.
It is a powerful analgesic which causes depression of the central nervous system. Large doses can therefore cause respiratory depression. A drop in blood pressure may also occur. Pethidine crosses the placenta and can cause respiratory depression in the newborn infant who may, therefore, need resuscitation at birth.
Morphine, which is less commonly used, has similar actions and side effects to pethidine.
An overdose of pethidine may cause respiratory depression in both the mother and her infant.
There is no limit to how late in labour pethidine can be given. If the patient needs analgesia she should be given the appropriate dose. However, if she receives pethidine within 6 hours of delivery, the infant may have respiratory depression at birth.
Pethidine may be given late in labour if needed.
If an adequate dose of intramuscular pethidine is given, it is usually not necessary to repeat the drug within 4 hours. (In South Africa registered nurses are allowed by law to give 100 mg pethidine by intramuscular injection during labour, without a doctor’s prescription, and to repeat the injection after an interval of 4 hours or more.)
Naloxone (Narcan) is a specific antidote to pethidine (and morphine) and will reverse the effects of the drug.
If a patient was given pethidine during labour, and delivers an infant who does not breathe well after birth, the infant should be given naloxone (Narcan). The correct dose of naloxone is 0.1 mg/kg (i.e. 0.25 ml/kg). A 1 ml ampoule contains 0.4 mg naloxone. Therefore, an average-sized infant requires 0.75 ml while a large infant up to 1 ml naloxone. Do not give naloxone to asphyxiated infants whose mothers have not received pethidine (or morphine). Naloxone will not reverse the respiratory depression caused by barbiturates (e.g. phenobarbitone), benzodiazepines (e.g. Valium) or a general anaesthetic.
Research has shown that the previously recommended dose (0.01 mg/kg) of neonatal Narcan is tenfold too low. The use of neonatal Narcan must, therefore, be stopped and replaced with adult Narcan.
Infants who do not breathe well after delivery should only receive naloxone if their mothers were given pethidine or morphine during labour.
Usually naloxone is given to a newborn infant by intramuscular injection into the anterolateral aspect of the thigh. The drug will reverse the effects of pethidine. Meanwhile, it is important to continue ventilating the infant. Naloxone can also be given intravenously. The drug acts more rapidly when given intravenously, e.g. into the umbilical vein.
Yes. A single dose of naloxone is almost always adequate to reverse the respiratory depression caused by pethidine. The action lasts about 30 minutes. Some infants may become lethargic after 30 minutes and may then require a second dose of naloxone.
In practice there are very few indications for the use of sedatives in labour. If a patient is restless or distressed, it is almost always because of pain and she therefore needs analgesia. The sedative effect of promethazine (Phenergan) or hydroxyzine (Aterax) together with pethidine will provide sufficient sedation for a restless patient. The dose is 25 mg promethazine (Phenergan) and 100 mg hydroxyzine (Aterax).
There is no role for sedation with tranquillisers e.g. diazepam (Valium) and barbiturates. Tranquillisers also cross the placenta and sedate the infant. Diazepam (Valium) can cause severe respiratory depression in the infant and this effect is not reversed by naloxone.
The most commonly used inhalational analgesic is Entonox. This is a mixture of 50% nitrous oxide and 50% oxygen. It is usually supplied in cylinders and is breathed in by the patient through a mask when she needs pain relief.
The advantages of Entonox are:
The disadvantages of Entonox are:
A patient requiring analgesia for the first time in advanced labour, where the delivery is expected within an hour.
No. Entonox is completely safe and cannot be used in excessive doses.
Entonox is a completely safe analgesic.
Local anaesthetics are drugs which are injected into the tissues and which result in a loss of all sensation in the injected area. Local anaesthetics often give a burning sensation which lasts 1 to 2 minutes while they are being injected. The patient should be warned about this before starting the injection.
Lignocaine (Xylocaine) is the local anaesthetic used most commonly. Although available in different concentrations it is best to only use the 1% solution. The possibility of giving an overdose will then be reduced.
There are two main indications for local anaesthesia in labour:
The maximum safe dose of lignocaine is 3 mg/kg body weight. 1 ml of a 1% lignocaine solution contains 10 mg lignocaine.
An overdose, or intravenous injection, of a local anaesthetic may cause convulsions.
Lignocaine results in loss of sensation in the infiltrated area for 45 minutes. If the maximum dose has already been given but more local anaesthetic is required, a further 10 ml or half of the amount determined by body weight of 1% lignocaine may be given after 30 minutes.
This is the ideal form of local anaesthesia as it offers the patient complete pain relief. Unfortunately special training and equipment are necessary for giving epidural anaesthesia and, therefore, it is only available in most level 2 and 3 hospitals.
Any pregnant or postpartum patient who receives a general anaesthetic has a very high risk of vomiting and aspirating her stomach contents because:
Patients who have been starved must be managed in the same way as patients who have recently eaten. During a general anaesthesic, the risk of the patient vomiting is particularly high during intubation and extubation.
A patient and her husband present at the maternity hospital. She is 26 years old, gravida 2 para 1 and at term. Her antenatal course has been normal and her routine observations on admission are also normal. The fetal presentation is cephalic with 2/5 of the fetal head palpable above the pelvic brim. The membranes rupture spontaneously and her cervix is found to be 5 cm dilated on vaginal examination. The patient is relaxed and does not find her contractions painful. She is admitted to the labour ward and given 100 mg pethidine and 25 mg promethazine by intramuscular injection as she is already in the active phase of the first stage of labour. Her husband is asked to wait outside the labour ward. It is suggested that he go home for a while as the infant is unlikely to be born during the next 5 or 6 hours.
No. She did not require analgesia. Not all patients need analgesia during labour. Some patients experience little pain during labour while others handle the pain of contractions with no difficulty.
The patient should have been reassured that her labour was progressing normally. She should have been encouraged to walk about and not spend all the time in bed. Analgesia need not be given routinely to all patients in active labour.
No. Most patients prefer to have someone they know well remain with them during labour. Her husband should have been encouraged to stay with her if that was what the patient wanted.
Simply being there is reassuring to the patient. He can help to keep her relaxed and comfortable. Furthermore, he can be shown how to rub her back during contractions.
Rubbing a patient’s lower back is of great help as the nerve impulses that come from the skin over the lower back travel to the same spinal segments as the nerve impulses from the cervix and uterus. The nerve impulses from the lower back partially block those from the uterus and cervix. As a result, the pain of contractions is experienced as less painful by the patient if the lower back is rubbed.
A 16-year-old patient presents in labour at term after a normal pregnancy. She is very anxious, does not co-operate with the labour ward staff and complains of unbearable pain during contractions. She bears down with every contraction even though the cervix is only 4 cm dilated. The patient is told to behave herself. She is informed that the worst part of labour is still to come and is scolded for becoming pregnant. As she is a primigravida, she is promised analgesia when her cervix reaches 6 cm dilatation.
Because she is unprepared for labour and does not know what to expect. In addition, she is in a strange environment and the staff are unfriendly and aggressive. Being anxious results in her experiencing her contractions as very painful while the pain in turn makes her even more anxious.
Receiving good information about the process of labour at antenatal visits, attending antenatal exercise classes and visiting the labour ward during the last weeks of pregnancy would have resulted in a far more relaxed patient in labour.
She should have experienced a pleasant atmosphere in the labour ward with understanding and encouragement from the staff. They should have reassured her that everything was under control and that there was no reason for her to be frightened. The staff themselves should appear confident, relaxed and caring. It is important that a family member or friend of the patient’s remain with her.
No. Tranquillisers, especially diazepam, should be used very rarely because they may result in severe respiratory depression in the infant at birth. This complication is not reversed by the commonly available drugs at delivery.
She should have been encouraged to concentrate on her breathing during contractions. In addition she should have been given adequate analgesia as soon as possible.
The ideal form of analgesia for this patient would have been an epidural anaesthetic as it provides complete pain relief. Alternatively she should have been given pethidine and promethazine (Phenergan) or hydroxyzine (Aterax) by intramuscular injection. The sedative effect of promethazine or hydroxyzine would have helped to lessen her anxiety.
Cervical dilatation in a multigravida patient in labour at term progresses from 3 cm to 8 cm in 4 hours. Now for the first time she complains that her contractions are very painful. The midwife informs her that she is progressing fast and that her cervix will soon be fully dilated. She adds that the patient must just continue without analgesia for the last 2 hours as the delivery will soon be over.
No. The patient needs analgesia and the most appropriate form of analgesia should be offered to her.
Entonox (nitrous oxide with oxygen) as it works rapidly and is completely safe. She also only needs analgesia for a short time as her cervix will soon be fully dilated.
Pethidine and promethazine (Phenergan) or hydroxyzine (Aterax).
The pethidine should preferably be given intravenously. Pain relief will then be obtained in 5 minutes and the effect of the drug should last 2 hours.
The infant may have respiratory depression and as a result may not breathe adequately at birth.
The infant must be resuscitated with oxygen and artificial respiration provided via a face mask or endotracheal tube. Naloxone (Narcan) must be given to the infant to reverse the effect of the pethidine. Naloxone is usually given by intramuscular injection. However, it acts more rapidly if it is injected into the umbilical vein.
A multigravida patient, who has had two previous Caesarean sections, is booked for an elective Caesarean section under general anaesthesia at 39 weeks gestation. The patient is admitted to hospital at 07:00, having had nothing to eat since 24:00 the previous night. She is prepared for surgery at 08:00. As the patient has been kept nil per mouth, no drug to prevent vomiting during intubation and extubation is given. Only an intravenous infusion is started and a Foley catheter passed before she is moved to theatre.
No. All pregnant patients are at risk of vomiting during general anaesthesia even if they have taken nothing by mouth during the past few hours.
Because her stomach has a delayed emptying time, the lower oesophageal tone is reduced and she has a raised intra-abdominal pressure.
Metoclopramide (Maxalon) 20 mg (2 ampoules) should have been given intravenously 15 minutes before the induction of anaesthesia. It is anti-emetic, it increases the stomach emptying time, and raises the sphincter tone of the lower oesophagus. These effects will reduce the danger of vomiting. An antacid should also be given before the general anaesthetic. The drug of choice is 30 ml of a 0.3 molar solution of sodium citrate.
The metoclopramide (Maxalon) acts for 2 hours so need not be repeated. However, the sodium citrate only acts for 30 minutes and, therefore, must be repeated before the start of the anaesthetic.