There are various types of pain relief for women in labour but not all provide effective and safe outcomes for both the mother and the infant such as: reduced pain intensity, satisfaction with pain relief, sensation of control of labour, satisfaction with childbirth experience, decrease in assisted delivery, caesarean section births, and adverse events (Jones et al. 2012). Women in labour are increasingly seeking non-pharmacological methods of pain relief while in labour; among the methods which may work include the use of acupuncture, immersion, relaxation, local anaesthetic nerve blocks and non-opioids for pain relief (Jones et al. 2012, Vixner et al. 2012, Smith et al. 2011). This study is looking at non-pharmacological method for pain relief in labour, with single needle acupuncture as the main method of pain relief. The literature review considers pain theories (sections 2.1 to 2.3) pain relief methods (section 2.4 to 2.6) and acupuncture as pain relief and its benefits (section 2.7 to 2.10).
2.2 Pain theories
Various definitions of pain exist. The variations exist because pain could be a manifestation of an underlying threat, danger or heralding an unpleasant event, this view supports the definition by the International Association for the Study of Pain (IASP) which defines pain as "an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage"(IASP 2012). The association considers pain to be subjective influenced by physiological, psychological and socio-cultural factors that were present in the individual at the time of the stimulus (IASP 2012).
How does the stimulus cause the sensation of pain? The stimulus carrying pain sensation to the brain, travel through Α δ and C fibers and the dorsal root ganglion cells to the dorsal horn of the spinal cord. From this point, the stimulus is processed, transmitted through the spinothalamic tract to brain stem, thalamus and cerebellum where spatial and temporal analysis occur, and to the hypothalamic and limbic system, where emotional and autonomic responses originate (Nina Kvorning).
To understand the mechanism by which the body mediates pain, communicates with the central nervous system and other parts of the body, certain theories have been put forward and would be considered by this study
2.2.1 Gate control pain theory
The theory alludes that pain stimulus travels from the initiation site by thin fibers which share similar gate with the thick fibers conveying touch, pressure and vibration. When there are more thick fibers conveying the stimulus, then the gates shut out the pain sensation reaching the higher centers in the brain (kanner, 2003).
2.2.2 Diffuse Noxious Inhibitory Control
Another theory for the pain mechanism is the diffuse Noxious Inhibitory Control (DNIC) which supports the fact that when a pain stimulus ascends towards the higher centers, another inhibitory stimulus from the higher centers can counter the pain stimulus abolishing the pain sensation (Le Bars2002).
2.2.3. Endorphins in labour
In the body exists naturally occurring opioid-like substances which moderate pain, they are endorphin, enkephalins and dynorfin which utilizes similar mechanism of action in the body as the opioids substances to relief pain (Guyton, Hughes, Terenius). Though levels of these substances continue to rise during pregnancy, and labour, their role is not clear as most women in labour still experience varying degree of pain (Pilkington, Gintzler, Varassi)
2.2.3 Labour pain theory as applied
The pain of labour is known to be norcipetive with stimulus transmitting via A d and C fibers which share the same pathways as the afferent stimulus from acupuncture (loeser and Bonica). Similarly, acupuncture studies suggests that the process releases neurotransmitters from the Central Nervous System (CNS) which are known to modulate nociceptive receptors (Han 2003) The pain from labour is norciceptive this research intend to evaluate if single needle acupuncture would modulate norciceptive stimulus providing pain relief in labour
2.3 Nature of labour pain
This section will take a closer look at the nature of labour pain.
Description Labour pain is often described by women experiencing their first pregnancy and childbirth as very severe (70-80%) while those women who have delivered before, describe the labour pains as being severe (50%) (Bonica, 1989).
Aetio-physiology of labour pain: The pain experienced by the woman in labour is caused by the uterine contractions and the dilatation of the cervix, and in the late first stage and the second stage by the stretching of the vagina and the pelvic floor to accommodate the presenting part (jones, 2012). Transmission of the stimulus is via spinal nerves T10-L1, with pains referred to abdomen, sacral region, iliac crests, gluteal areas and thighs. From the second stage of labour, the pain arises from distension of the vagina, perineum and pelvic floor. The impulses are transmitted via the nerve roots S2-S4 unto the spinal cord (Rowlands and Permezel 1998) The impulses from the uterine contractions are carried along A-delta and C afferents to the spinal cord, the site of transmission to nerve cells that in turn transmit the information all the way to the cortex where an interpretation of the impulses takes place (Martenssen)
Women perceptions and experiences of labour pain: Perception of labour and its experience vary between women as it ranges from widespread and diffuse to a well-defined and localized pain (Melzack and Wall, 1984). The view also exists that nulliparous woman experiences more pain when compared to the multiparous counterparts during the early phase of labour (Lowe, 2002). Women in labor who adopt either the upright position or lateral position experience severe pain in labour as compared to women who adopt the supine position in labour (Gupta, 2006)
Psychological factors: The fear-tension-pain cycle alludes to the fact that pregnant women often have an increased psychological perception of pain in labour (Dick and Read 2004). This perception is often modified by previous experience of labour and childbirth, culture and ethnicity, educational attainment and a woman's ability to cope are often suggested as significant mediating variables on the experience of labour pain (Jones 2012).
Pain measuring scales: There are three commonly used pain measuring scales namely; the Visual Analogue Scale (VAS), Verbal Rating Scale (VRS) and Numeric Rating Scale (NRS). According to Williamson and Haggard (2005), all the three pain-rating scales are valid, reliable and appropriate for use in clinical practice, although the VAS has more practical difficulties than the VRS or the NRS (Williamson, 2005). The NRS appeared to be a valid measure. It was as successful as the VAS in measuring the underlying pain variable. It was easier to administer and code than the VAS, and was sensitive to change in pain (Ritter, 2006)
2.4 History of pain relief methods in labour
The influence that the church weighed over medical practice delayed introduction of pain relief methods based on the biblical instruction which decreed that women would bear forth their children with some form of sorrow (GNT). However, by the 18th century, following the discovery of ether and an anesthetic gas, it was used as a pain relief in labour which was followed a year later by chloroform. However, the side effects of hallucinations, nightmares and cramps lead to it not being popular among the physicians of that time as well as the clergy opposition (58). When Queen Victoria had her eighth and ninth child with the aide of some form of pain relief, the method finally acceptance within the clergy as well as clinicians ()
2.5 Pharmacological pain relief methods in labour
2.5.1 Inhaled anaelgesia
Inhaled analgesia during labour involves the inhalation of sub-anaesthetic concentrations of anaesthetic agents while the mother remains awake and her protective laryngeal reflexes remain intact. The advantages of the inhaled anaesthesia include; ease of administration, relative lack of flammability, absence of pungent odour, absence of effect on uterine contractions, lack of reports of malignant
hyperthermia, minimal toxicity and minimal depression of the cardio-vascular system; a favourable partition coefficient leading to rapid onset and elimination from woman, fetus and neonate (knov, Rosen, 2002). The negative side effects when used improperly by the mother may include maternal drowsiness, hallucinations, vomiting, hyperventilation and tetany, and maternal or fetal hypoxia ( BOC, 2010) The continuous exposure to the inhaled anaesthetic agents by medical staff is its major disadvantage cause there is concern of loss of fertility, miscarriage, preterm birth and lowered concentrations of vitamin B12(albong etc)
Definition benefit and side effect
2.5.2 Opioids
Use of narcotic agents for pain relief in labour is increasingly becoming popular in most labour wards globally with popular opioids being morphine, nalbuphine, fentanyl and remifentanil (Evron 2007). However there is concern their effects in suppressing the mental judgement of women in labour, sedation, hypoventilation, hypotension, prolonged labour, urine retention, nausea and/ or vomiting, and the slowing of gastric emptying, which increases the risk of inhalation of gastric contents should a general anaesthetic be required in an emergency.(Lawrence 2009). For the infants, it cause respiratory depression, cardiac deceleration, delayed initiation of breastfeeding, and hypothermia (shekavat, 2007)
2.5.3. Non-opioids drugs
Acetaminophen and NSAIDs can effectively relieve mild to moderate pain, and for moderate to severe pain, they can be used in combination with other drugs to enhance pain relief in labour. The Non-opioids drugs act by chemical changes at the site of the injury typically result in inflammation and increased pain sensitivity. However, there are limits to the pain afforded by non-opioids; this is referred to as a 'ceiling effect'. Once that upper limit or ceiling is reached, taking more of the non-opioid will not provide any further pain relief (jones 2012). Their side effects are mostly over prolonged use for chronic pain (barayski Deuhurst)
2.6 Non-pharmacologic pain relief in labour
Increasingly gaining popularity among women who are in labour as a means of coping with labour pain during child birth (jones 2012)
2.6.1 Hypnosis
According to Gamsa (2003), Hypnosis describes a state of narrow focused attention, reduced awareness of external stimuli, and an increased response to verbal or non-verbal communications that result in apparent spontaneous changes in perception, mood or behaviour (Gamsa2003). Hypnosis for childbirth is self-hypnosis, where a practitioner teaches the mother how to manipulate her consciousness to a state similar to meditation which results in failure of normally perceived experiences reaching conscious awareness thereby minimizing the pain of labour (Cyna 2004). The disadvantage is the poor perception that women practising self-hypnosis lose their thought processes and mental state, which is quite contrary as self-hypnosis allow them control their physiology and psychology thereby breaking the cycle of fear-tension-pain associated with labour (landon 2011 Eng 2006)
2.6.2 Acupuncture
Acupuncture is the process of inserting specialised needles into specific points on the skin to a certain depth to impede stimulus in the central nervous system (jones 2012). Acupuncture will be discussed in details subsequently.
2.6.3. Aromatherapy
The process involves the application of essential oils found in plants on the skin, or inhaled or dispensed into the air for women in labour and is thought to affect their physiology and psychology resulting in the body's own reaction by secreting its natural relaxant neurotransmitters assisting the woman cope with pain in labour ( stevensen 1996)
2.7 Acupuncture
Acupuncture (Latin: acus - needle and punctum - puncture) is an ancient method and component of traditional Chinese medicine, in use for centuries. Acupuncture entails penetration of the skin with thin needles at certain points on the surface of the body. These points follow a predictable pattern and the lines linking the points are known as meridians
2.7.1 History of acupuncture and acupuncture in relieving labour pains
Acupuncture was originally developed in China more than 3000 years ago. It is one of several modalities which constitute traditional Chinese medicine. Use of the method for labour pain relief has increased rapidly in the 1990s
2.7.2 The mechanism of action of acupuncture
2.7.3 The efficacy of acupuncture
2.7.4 The pressure points used in acupuncture
2.7.5 Types of acupuncture
2.7.6 The single needle in the management of labour pains
2.7.7 Single needle versus multiple point acupuncture
2.8 Satisfaction with labour experience related to pain
Definition scales that measure it and what does literature states
2.9 Experience of pain during labour
2.10 Relaxation during labour
2.11 Summary of chapter
