Pharmacological and Non-pharmacological Approaches to Reduce Labor Pain - Research Paper Example

The current report addresses the question Are pharmacological approaches including analgesics through epidural or injection more effective than non-pharmacological approaches including acupuncture and relaxation technique? Labour pain has been an integral part of child bearing process. Several pain relief measures are known; pharmacological as well as non-pharmacological or alternative. While the latter find origin in different cultures and have been used traditionally and popularly, they still lack scientific evidences. The pharmacological measures include analgesia which vary in type and mode of administration. Despite the universality of the association of pain with labour; an appropriate pain relief strategy is yet to be researched. The probable cause of this is the lack of controlled trials providing evidences for their relative efficacy. The problem is further complicated by the wide variety of traditionally practiced techniques which though reported to be effective, lack scientific data. The current report discusses the relative efficacy of the pharmacological technique of epidural analgesia that is being frequently used in the recent years; and analgesic injection, a widely used but equally controversial measure. The study further compares the efficacy of non-pharmacological techniques of relaxation and acupuncture. Though only epidural analgesia was concluded to be an effective measure of pain relief on the basis of available literature, further researches are needed to assess the efficacy and drawbacks of the rest. Are pharmacological approaches (analgesic e.g. through epidural or injection) more effective than non-pharmacological approaches (acupuncture and relaxation technique) in reducing labour pain? BACKGROUND Pain has intrigued science of medicine for centuries. Symptoms of pain are difficult to ignore and yet the cause isn’t easy to deduce. It involves intolerable agony for some and some derive pleasure from pain. In some situations the excruciating pain is borne without a twinge, while in others a mild pain can be unbearable (Wall, 2000). Pain involves our state of mind, our social mores and beliefs, and our personal experiences and expectations. The way we deal with pain is an expression of individuality.” Patrick David Wall Pain and pain control Rene Descartes in his essay “L’Homme” attributed reflex behaviours of animals to pain stimuli to ‘animal spirits’ flowing through their nerves (Arnaldo & Joyce, 1999). Centuries of research have resulted in a precise comprehension of the concept and mechanisms of pain. It is now known that sensory pathways commencing with a stimulus effect and are converted by sensory receptors into neural signals through transduction. These neural signals are transmitted to the brain and are interpreted. Thus perceiving a sensation involves its conversion from an electrical impulse to a psycho-somatic phenomenon with multiple advanced repercussions (Hains, 2007). Though one of the most common symptoms dealt with by the physicians and experienced by an individual, pain is difficult to define. International Association for the Study of Pain defines pain as “an unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage” (Chen, 2004). Several theories have evolved with the growth of scientific researches in the field of medicine and technology (Gatchel et al., 2007). While the classical theories stressed the physiological aspects of pain, the multidimensional theories included the physiological as well as psychological, cognitive and social aspects of pain (Gatchel et al., 2007). Mechanism of pain, in its most simplified version involves stimulation of pain receptors followed by transfer of stimulus to spinal cord and then to brain through specialized peripheral nerves. Nociception is the process encompassing pain processing and involves four basic processes of pain transduction, transmission, perception and modulation (Mccaffery & Pasero, 1999). Figure 1: Mechanism of Pain (Jarvis, 1990) Clinicians investigate patients’ history of pain to identify the source and thereby recommend pain management strategies. The critical points in pain history are identified on the basis of the mnemonic “P, Q, R, S, T” (figure 2) (Jarvis, 1990). Figure 2: Critical points in pain history (Based on Jarvis, 1990) The major goal of pain management strategies is to reduce pain along with control of acute pain and prevention of further injury to the patient (ICSI, 2008). Labour pain Labour pain or the pain associated with the process of childbirth is a complex phenomenon resulting from interaction of physiological and psychological; excitatory and inhibitory processes (Rowlands & Permezel, 1998). During the initial stage of labour, pain similar in experience to abdominal cramping occurs as a consequence of distension of lower uterine segment, mechanical dilatation of cervix, and expansion of excitatory nociceptive afferents. The last factor results as a consequence of the contraction of uterine muscles that form the myometrium (Melzack & Wall, 1996). During the next stage pain intensifies and is no more intermittent due to additional factors such as pressure as well as traction on parietal peritoneum, urethra, bladder, rectum, uterine ligaments, fascia and muscles of pelvic floor. Nerve entrapment or pressure due to baby’s head can further cause severe back or leg pain. Pain intensity correlated with stages of labour as well as pain bearing (Baker et al., 2001), is affected by the presence or lack of prior childbearing experiences (Ranta et al., 1996). The neural pathways associated with labour pain involve the afferent nerve fibres that supply the uterus and cervix. The unmyleniated ‘C’ visceral fibres are responsible for the transmission of nociception to 10th, 11th, and 12th thoracic nerves as well as the 1st lumbar nerves and to dorsal horn synapse (Kuczkowski, 2007; Bonica & McDonald, 1990). The pathway is also mediated by chemicals such as bradykinin, leukotrienes, prostaglandins, serotonin, lactic acid and substance P (Rowlands & Permezel, 1998). Labour pain is also associated with stress responses in the respiratory and cardiovascular system along with hormonal changes. It affects the metabolism of both the foetus and the mother. During the stages of labour pain hyperventilation leads to respiratory alkalosis and hypocarbia followed by compensating acidosis. Oxygen demand increased due to enhanced oxygen consumption is further intensified as a consequence of lower tissue oxygen transfer (Frye et al., 2011; Brownridge, 1995). The cardiovascular system is also stressed due to enhanced stroke volume with maximum increase in cardiac output experienced immediately after birth as a consequence of enhanced venous flow post relaxation of venacava compression (Sohnchen et al., 2011; Lowe, 2002). Pain initiates the release of beta-endorphin and ACTH, the enhanced anxiety further causing pituitary secretion (Fajardo et al., 1994). Adrenaline as well as noradrenaline are secreted from the adrenal medulla causing peripheral resistance and enhanced cardiac output. In the mother’s body levels of growth hormones, rennin, glucagon and anti-diuretic hormone (ADH) rise while those of insulin and testosterone fall during labour (Risberg, 2009). Factors affecting labour pain Though the association of labour and pain is strong and undeniable, there are several obstetric, environmental and psychological factors that influence the nature, intensity and handling of this pain. On one extreme is the probably ‘unreasonable’ dread of the childbirth process coining the term ‘tocophobia’ (Hofberg & Ward, 2004); and on the other hand is the pro labour pain concept claiming it to be a preparation for the more demanding job of child rearing (Jordaan, 2009). Among the physiological factors affecting the severity of labour pain the prominent ones are foetal size, maternal fitness levels, posture, stature, and sensitivity; and primiparity. The maternal psychological factors determine the handling of pain by the mother. Thus control and feeling of self efficacy of the mother are important factors determining the handling of the childbirth and associated pain (Simkin & Bolding, 2004; Lowe, 2002). Labour pain control Mechanisms of control of labour pain can be broadly categorized in to two groups: those occurring within the maternal body as preparatory mechanism, and the ones administered from outside. The latter can further be classified as pharmacological and non-pharmacological (also known as complementary or alternative methods) (Mander, 2011). Among the theories attempting to account for the body’s internal mechanisms of pain control, the most accepted theory is the Gate Control Theory. Initially proposed in 1965 and later refined in 1988 by Melzack and Wall. According to this theory pain perception involves A-d and C nerve fibres that are involved in sharp, aching or burning pain sensation; along with A-b beta nerves that are present in skin and are responsible for sensing touch, pressure, heat and cold. The latter larger fibres being quicker inhibit the transmission of pain sensations by the former smaller nerves acting as ‘gates’. However when the pain is intense the ‘gate’ is forced open, rendering the pain sensation highly intense (Mårtensson et al., 2008). Endorphins are also part of the body mechanism to control pain sensation acting as natural opiates, similar in action to analgesics (Deakin et al., 1980). The maternal body in preparation of the labour process begins to synthesize higher levels of endorphins prior to entering labour (Jones et al., 2011; Iverson, 1979). Non Pharmacological Methods of control of Labour Pain Psychoprophylaxis Psychoprophylaxis or prior psychological preparation for labour pain through education, positive attitude development staff support and antenatal relaxation techniques reduce the need of pharmacological interventions for pain relief (Cyna et al., 2004). Antenatal tutorials involve training for breathing and calming exercises. Further music (Browning, 2000), aromatherapy, massage and warm baths (Ohlsson et al., 2001) on one hand are soothing as well as provide distraction during the pain. Transcutaneous Electrical Nerve Stimulation (TENS) TENS involves electrical stimulation of dorsal columns of spinal cord using high frequency low intensity current (0-40mA at 40-150MHz). Two electrodes each are placed over the dermatomes of T11-L1 and S2-S4, over intact skin. While the low intensity signals are known to initiate release of endorphins, the high frequency shut spinal neuronal gate. The cumulative impact of the two is to block the pain stimuli, thereby reducing pain sensation (Bedwell et al., 2011). Besides these several complementary and alternative techniques such as body postures and positions (Michel et al., 2002), acupuncture (Nesheim et al., 2003) and acupressure, hydrotherapy, homeopathy, hypnosis (Cyna, et al., 2004), naturopathy, massage (Chang et al., 2002) or Shiatsu and many herbal preparations are traditional used to provide pain relief in different cultures; though most of these are still not backed by scientific data supporting their efficacy (George et al., 2009). The major advantage of non-pharmacological methods is that multiple methods can be used simultaneously or in rotation as the need arises with progressive stages of labour (Smith et al., 2004). Pharmacological Methods of Labour Pain Control Pharmacological methods of pain relief involve the use of several analgesics and anesthesia administered intravenously, intramuscularly or through inhalation. The strategies vary with respect to choice of analgesic and the manner of administration. Systemic opiates such as Pethidine, Morphine and Fentanyl as well as non opiates such as ketamine are commonly used analgesics. Analgesic Injections Pharmacological pain relief is primarily based on the administration of systemic opioids injected in combination with or without sedatives or anti-emetics. Pethidine and diamorphine alone or in combination are popularly used, though there are risks of side effects such as nausea, hypotension, gastric stasis, respiratory depression to the mother and lower neonatal apgar score and respiratory depression. Anti-emetics are administered therefore to overcome nausea due to opioids. In cases of excessive anxiety, sedatives such as benzodiazepines are given. To counteract respiratory depression naloxone is used (Ullman et al., 2010). Inhalation Analgesics Among the inhalable analgesics the most commonly used is nitrous oxide, administered in combination with oxygen (50:50). Volatile agents such as isofluorane (0.75%) or sevoflurane (0.8%) are also used at low inspired concentrations (Klomp, et al., 2011). Pudendal Analgesics Pudendal analgesics are local anaesthetics administered using the pudendal needle that is inserted in the sacrospinous ligament through which passes the pudendal nerve. This is useful especially in low outlet forceps or venthouse delivery (Jones et al., 2011). Regional Analgesia Lumbar Epidural Analgesia is the most common form of regional analgesia administered in cases of slow and long labour, maternal cardiac or respiratory disease, occipito-posterior presentation and during multiple pregnancy. The process involves an initial intravenous infusion of 500-1000ml of crystalloid fluid followed by a test dose of a short term anesthetic such as lidocaine through an epidural catheter. Next if the situation remains normal, either repeated doses or regular infusion of long term anaesthetic such as bupivacaine is administered with simultaneous monitoring of signs of maternal hypotension and baby’s distress. Epidurals may also involve many other complications such as reduced maternal urge to push as a consequence of relaxed pelvic floor. Cases of dural puncture causing CSF leak and spinal headache have also been reported. Such complications render sound judgment with respect to decision regarding epidural analgesia imperative (Datta et al., 2010). Another form of regional analgesia is spinal analgesia or an injection of local anaesthetic in the sub-arachnoid space. This is effective for 2-4 hrs and is useful for caesarean section and other instrumental deliveries. They carry complications similar to epidural analgesia. However, regional analgesia is the most effective and also lowers the need for general anaesthesia in cases of operative deliveries. Combined spinal and epidural technique (CSE) carries additional advantage of immediate analgesia from spinal components along with maintenance of epidural analgesia (Schewe et al., 2009). Research Question On the basis the preceding discussion it can be stated that: 1. Labour and pain exhibit eternal association. 2. Multiple techniques of labour pain relief are available and popularly practiced. 3. Immense and exhaustive research have been conducted to test the administration and efficacy of these techniques. 4. In spite of the above three clauses, the process of child birth continues to be associated with pain, usually severe and unbearable. Thus an important question that needs to be reviewed is “Are pharmacological approaches (analgesics through epidural or injection) is more effective than non-pharmacological approaches (acupuncture and relaxation technique)?” The following discussion is aimed at finding an appropriate answer to the research question. DISCUSSION Just as no two babies born are alike; so are no two deliveries and associated conditions alike. Each mother, and child birth process is unique and comparisons or generalizations are inappropriate. However, certain techniques that were effective in providing pain relief to a studied group of mothers have higher probabilities of being effective for others as well. On this premise, the current report aims to make a comparative assessment of the efficacy of selected pharmacological (epidural and injection analgesia) and non-pharmacological (relaxation and acupuncture) techniques for pain relief during labour. Relaxation Relaxation techniques include a wide variety of strategies such as breathing exercises, postures and positions, music and labour support. Childbirth education tutorials provide instructions as well as rehearsals to pregnant women regarding these techniques and their utility. The technique has been reported to be effective in providing pain relief; however these reports are not backed by scientific data. No randomized control trials assessing the efficacy of relaxation techniques exclusively are available. However there are reports of surveys conducted on American women. Of the women surveyed, 61% confirmed to have used relaxation techniques of which only 69% considered them to be slightly or extremely useful; and 30% reported them to be “not very useful”. These techniques are employed to enable women to gain confidence and a feeling of control. Hence they are frequently employed only during early stages of labour. There are no known disadvantages of the use of these techniques (DeClerq et al., 2002). Acupuncture Acupuncture originated in China and has been in use for thousands of years. The technique involves insertion of fine needles at specific points in the body that intend to rectify energy imbalances. Modern acupuncture techniques are based on identification of trigger points, segmental points and formula points and attempts have been made to provide explanations for the same on basis of neurophysiology and anatomy. This theory finds support in the fact that most acupuncture target points are located in the vicinity of neural structures; correlating them with the nervous system. Another mechanism of action of acupuncture is based on their stimulation of endorphins (Stener-Victorin et al., 2006). However the World Health Organization (WHO) essentially categorizes acupuncture as non-pharmacological method (Ramnero et al., 2002). The technique has been used for labour pain relief since 1970s however there was complete lack of scientific data supporting its efficacy. Among the first RCTs conducted to evaluate the efficacy of acupuncture techniques exclusively for pain relief during labour was a study conducted by Ramnero and colleagues (2002) in Sweden over a 14 month period. 46 patients receiving acupuncture treatment in lieu of analgesia were observed and the efficacy of the technique was assessed based on the criteria of pain intensity, relaxation and delivery outcome. It was observed that acupuncture reduced the need for epidural analgesia and provided higher degrees of relaxation. Moreover no negative effects were reported as a consequence of acupuncture. Several recent studies however do not provide significant benefits of acupuncture. In comparison to absence of pain relief strategies, acupuncture has been reported to provide relief only during the first 30min of labour (Ramnero et al., 2002). In another study, compared to conventional analgesia lower doses of analgesics were needed by women receiving acupuncture (Borup et al., 2009). Thus no conclusive statement can be made on the basis of the available literature on the efficacy of acupuncture because of the vast variability in the nature of the studies and inadequate number of evidences available. Epidural Analgesia Epidural analgesia has been use for labour pain relief since 1946 but its use has been found to increase rapidly during the last two decades. Available data indicate that approximately 20% of women in UK and 50% in USA use epidural analgesia for labour pain relief (Khor et al., 2000; Declercq et al., 2002). Though drugs and protocols used for the technique vary but the technique has proven efficacy for pain relief (Howell et al., 2001). Besides this epidural analgesia being regional provide the added advantage to women since they are alert and active part of the child birth process. The commonly used epidural drugs for labour pain are local anaesthetics. It has been reported that low dose anaesthetics such Bupivacaine are effective and involve lower risk since they have minimum placental accumulation. Addition of opioids to anaesthetics has been known to reduce the effective doses of LA, and hence reduces the risks of toxicity along with effective pain relief (Paech, 2000). However there are also several disadvantages related to the technique such as risk of inadequate analgesia. Reports of maternal hypotension leading to reduced oxygen supply to the baby in extreme cases are also available (Vincent & Chestnut, 1998). Besides this urinary retention, itchiness, drowsiness, etc have also been reported (Liang et al., 2002). Epidural analgesia have also been associated with higher risks of caesarean sections and instrumental deliveries, however in absence of adequate evidences the issue remains debatable (Lieberman & ODonoghue, 2002). Injection Analgesia Systemic opioids such as pethidine, diamorphine, meptazinol, pentazocine etc administered intramuscularly are widely used for labour pain relief with (39%-56% cases in America). Among these the most common is pethidine administered at doses of 50-100mg effective within 15 minutes and its impact lasting for 2-3 hours. However, very few studies support the use of systemic opioids with most providing evidences for their inefficacy (Olofsson et al., 1996). Further opioids have been associated with several adverse impacts on both the mother and the baby. Pethidine has been known to traverse the palcenta and accumulate in faetal circulatory system risking the survival of the baby. These issues render the testing of systemic opioids unethical and controversial, leading to inadequate number of placebo controlled RCTs available. A prospective double blind pacebo controlled RCT conducted by Tsui et al (2004) has provided valid evidence proving the efficacy of pethidine for labour pain relief compared to placebo however, its analgesic effect was found to be mild. For the other opioids adequate data enabling there assessment and estimation of their comparative efficacy in pain relief is lacking (Elbourne & Wiseman, 2002). CONCLUSION Childbirth definitely is one of the most painful experiences an individual is likely to suffer and every woman about to deliver a new born is apprehensive of it. The anxiety and the fear can only be partially overcome by pre-labour preparedness and labour support. Adequate as well as appropriate pain relief measures are essential to ensure the safety of the mother and the baby. Further adequate research providing evidence for their efficacy as well as side effects; both immediate and long term; and on both maternal and baby health is needed. Among the methods studied; sufficient data is available exclusively for epidural analgesia. Epidural analgesia have been reported to be more effective pain relief measure compared to other techniques but involved the risks of longer first stage of labour and caesarean sections. Further studies have failed to make an assessment of some of the rare adverse impacts of epidural analgesia. Studies involving larger sample sizes are needed to estimate the frequency and risks associated with these. Further data regarding the long term impacts of epidural analgesia are also completely lacking. Studies need to be planned to enable assessment of short term risks as well as long term impacts of the technique. Intramuscular analgesia on the other hand is much lesser studied though more prevalently used. The use of Pethidine is based on its low cost and easy availability as well as administration. But the drawbacks of the use of these opioids needs to be well documented to enable an informed decision for their use, both on part of medical supervisors as well as patients. Use of acupuncture as a pain relief measure does not find support in scientific investigation. However evidences are insufficient to make a conclusive statement possible. Further researches are needed to provide sound evidences for their efficacy as well as side effects. Relaxation techniques on the other hand determine solely the level of preparedness of the women during labour and are not effective in providing pain relief. References 1. Arnaldo, B., & Joyce, A. 1999. Rene Descartes physiology of pain. Spine , 2115. 2. Baker, A., Ferguson, S. A., Roach, G. D., & Dawson, D. 2001. Perceptions of labour pain by mothers and their attending midwives. Journal of advanced nursing , 171-9. 3. Bedwell, C., Dowswell, T., Neilson, J. P., & Lavender, T. 2011. 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