Using Entonox in labor

Entonox - or ‘gas and air’, as it is popularly known, is a 50-50 mixture of oxygen and a gas called nitrous oxide. It is the latter component that is aimed at the pain.

Entonox is a rapidly acting agent but the action lasts only a short duration, usually no more than 60 seconds after the last inhalation.

Probably the main attraction of Entonox is the fact that it is inhalational (no needles involved!) and is self-administered. This means the mother can have it if and when she wants it.

Many women find it quite helpful but are rather frustrated by its short duration of action. This means, if a woman uses it exclusively, she has to keep breathing on it practically continually.

Other women find it disagreeable because of the sedative effect it produces. In fact, some women fall asleep between contractions because they have been pulling energetically on the gas and air. The majority of women will probably be of the opinion that at the height of labor pains, especially with pushing in the second stage of labor, gas and air is hardly ever adequate.

Entonox does not have any adverse effects on the baby.

Painkillers given by injection in labor

Pethidine is the most common injectable analgesic (painkiller) used in labor. Debate still rages on the effectiveness of this drug in controlling pain. There is no question that Pethidine has a strong sedative effect and there is quite a large section of the obstetrics and midwifery fraternity who believe that pethidine actually works through sedation rather than true pain relief.

There are many women in labor who have reported finding Pethidine totally inadequate. The most common side-effect of pethidine is nausea and vomiting. In many units, an anti-emetic (anti-sickness) drug to counter this is routinely administered with pethidine. Other units have a policy of administering an anti-emetic only if the laboring woman complains of nausea and/or vomiting.

Pethidine can be given repeatedly every three hours or so, depending on requirements.

Using Diamorphine for pain relief in labor

Diamorphine is another popular choice in labor. Diamorphine is synthesized from morphine and in fact it partially converts back to morphine once in the body. Diamorphine and heroin are the same thing.

The drawback is that this very powerful narcotic cannot be given repeatedly. This is because the problem of dependency sets in rather rapidly. In most units, it will be administered as a one-off at the onset of painful contractions or at any time in labor when the mother is in marked distress because of the pain. This occasional use does not carry the risk of dependency.

Another positive aspect of Diamorphine is the fact that it causes less nausea and/or vomiting when compared to Pethidine.

Other injectables that have been used in labor but are less common include Meptazinol (Meptid®) and Pentazocine. They are both morphine-related opiates. They have no particular advantage over Pethidine.

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