Guide to Pain Management in Low-Resource Settings
What if Shillah continues to have neuropathic
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- Case report 2 (analgesia when breastfeeding)
- Does pain after cesarean delivery really need to be treated well
- What should the “district” hospital be able to off er Agnes
- What are the eff ects of these drugs on the breastfed baby
- What other methods might the city referral hospital be able to off er Agnes
- Might any other local anesthetic blocks be useful in reducing Agnes’s risk of having poorly controlled pain
- Case report 3 (analgesics in later pregnancy)
- What sort of painful conditions occur during pregnancy
- What initial treatment would you suggest for Martine
- Would local anesthetics or opioid drugs be suitable in this case
What if Shillah continues to have neuropathic pain later in pregnancy? Good levels of evidence support both the effi cacy and safety of typical doses of amitriptyline (initially 10–25 mg orally at night). Ketamine, another potent analgesic, can be eff ective for both acute and neuropathic pain, although oral tablet or lozenge forms are still being de- veloped. Ketamine has been used in large numbers of pregnant women without links to malformations, so it is considered safe, making it a valuable option when patients are admitted to hospital when either acute or neuropathic pain is diffi cult to manage(bolus up to 0.25 mg/kg and initial infusion rate 5–10 mg/h). Because lo- cal anesthetics are safe during pregnancy, lidocaine (lig- nocaine) infusion (1 mg/kg over 20 minutes then 10–30 mg/h, see the chapter on neuropathic pain) is another option that is eff ective in a minority of patients with neuropathic pain. If gabapentin is available, it can be considered. It does not cause major malformations in animal stud- ies and has not demonstrated evidence of harm in lim- ited human experience to date. Mexiletine also appears to be of low risk to the fetus, but it is less eff ective and has more side eff ects. In contrast, carbamazepine, al- though still used during pregnancy in some epileptic patients because its benefi t is considered to outweigh the risk of harm, should be avoided, even after the fi rst trimester, because it causes major and minor abnor- malities, including spina bifi da, craniofacial defects, and coagulation disorders in humans. Th e selective se- rotonin reuptake inhibitors and similar drugs (citalo- pram, paroxetine, venlafaxine), lamotrigine (an anti- convulsant) and pregabalin (a voltage-gated calcium channel blocker) have limited information available and are best avoided. 238 Author(s) Case report 2 (analgesia when breastfeeding) Agnes is a 28-year-old multigravid woman who has two children and is now 34 weeks pregnant. She comes from a good and sensible family that is well known to you. She has come to you for advice because the obstetrician has just booked her for an elective repeat cesarean delivery in 1 month. She has been told that the baby appears to be much bigger than last time, when she experienced failed progress of labor and had to have an urgent cesar- ean section. Although she has been doing well and un- derstands why it would be best to have another cesarean, she is very anxious and is not sure whether to have her operation at the district mission hospital or whether to ask if she can go to the referral hospital in the nearby city with better facilities. Agnes is worried for two reasons. First, after her last cesarean she had a lot of pain, especially during the fi rst two days, and she is scared about suff ering the same experience. Second, local women elders had told her that if she had any strong painkillers after the operation, the baby would not be able to breastfeed—but she can- not aff ord to use milk formula. You listen sympatheti- cally because you are aware that many women are not getting very good pain management after their cesarean at the district hospital. You are planning to talk to the doctors there to suggest some simple changes that you think will improve the situation signifi cantly. You dis- cuss with Agnes the options that are likely to be avail- able for her postoperative analgesia at the two hospitals and their implications when she starts to breastfeed— and then you make some recommendations and prom- ise to contact the hospital to try and make sure she gets satisfactory treatment. Does pain after cesarean delivery really need to be treated well? Most women experience moderate to severe pain in the fi rst 48 hours after abdominal surgery, including ce- sarean section, and both mother and baby will benefi t from good pain relief. If the mother is able to move in relative comfort, she can mobilize soon after recover- ing from the anesthetic (within a few hours of surgery after a spinal anesthetic), which reduces the risk of pul- monary infections and venous thromboembolism, an important cause of sudden death from pulmonary em- bolism. She will be able to eat within hours of the op- eration and continue to care for and interact with her baby, while establishing lactation and breastfeeding. Eff ective, regular, and early pain relief reduces the risk of moderate or severe pain after the fi rst one to three days such that most women need only paracetamol (acetaminophen) and/or an NSAID by the third to fi fth postoperative day (and may reduce the risk of chron- ic wound pain later!). Most methods of postcesarean pain relief are based on opioids, the majority of which are considered safe for the breastfed baby if used only short-term during lactation. What should the “district” hospital be able to off er Agnes? Th e best approach to acute pain management for Ag- nes is a “multimodal” approach, which means combin- ing diff erent painkillers or analgesic methods to reduce the dose and thus side eff ects of each component. An opioid such as morphine should be prescribed, pref- erably using regular doses with extra supplementary doses if requested, for the fi rst 24–48 hours. If an in- travenous method (patient-controlled analgesia or continuous infusion, see below for these referral hos- pital methods) is unavailable, then the oral or subcuta- neous route can be used. Intramuscular injections are more painful than subcutaneous (especially if the latter are given through a small cannula or ‘butterfl y” nee- dle); they have a higher risk of deep infection and are no more reliable in their effi cacy. Giving the opioid “as required” leads to undertreatment and poor pain relief because of inconsistent absorption pharmacokinet- ics and individual response. If a range of doses is pre- scribed, then the smallest can be used fi rst and substi- tuted with a larger dose subsequently if required. Th e drug of choice is morphine, which may be available as a tablet or oral syrup (30–45 mg every 8 hours) or a parenteral formulation (subcutaneous 10–15 mg every 6 hours). Oral codeine (60 mg every 6 hours) should only be used if another oral opioid is not available. During lactation, pethidine (meperidine) should be avoided unless there is no other alternative. It has an active metabolite, norpethidine (normeperidine), that has a very long elimination half-life in the newborn (approximately 72 hours), and as both accumulate in the neonate, the baby becomes sleepier and less active, and its ability to suck on the breast is impaired. Th ese eff ects are prominent when intravenous doses are giv- en after cesarean delivery, but they also occur from lower intramuscular dosing during labor. If the baby is very premature and has worrisome apneic spells, all Chapter Title 239 opioid doses should be minimized and if possible sub- stituted with tramadol, which is safe for the baby in the fi rst few days after delivery when breastfeeding is be- ing established. Every attempt should be made to make sure that Agnes also gets either an NSAID such as diclofe- nac (a second choice is indomethacin, which has more side eff ects), paracetamol (acetaminophen), or even both. Th ese painkillers reduce the dose of morphine needed by 30–40% and 10–20% respectively, and an NSAID can reduce “cramping” pain from the uterus. Oral paracetamol (1 g every 6 hours) has almost no side eff ects and is contraindicated only in patients with severe liver dysfunction. An NSAID, preferably given at its maximum recommended dose (e.g., diclof- enac 50 mg t.i.d. [three times daily] or indomethacin 100 mg b.i.d. [twice daily]) and with food to avoid gas- trointestinal upset, is contraindicated in women with hypertensive disease including preeclampsia, renal impairment, peptic ulcer, or symptomatic refl ux dis- ease, and in women with a bleeding disorder or cur- rent bleeding risk. An additional measure for the surgeon, that is not too expensive, is infi ltration of local anesthetic (for example, 0.25% bupivacaine up to a maximum dose of 2 mg/kg) into the wound. Skin infi ltration alone is not eff ective, but injection beneath the rectus sheath fascia and subcutaneously may reduce the amount of opioid needed, with a low risk of complications. What are the eff ects of these drugs on the breastfed baby? With a couple of exceptions, especially those apply- ing to pethidine (meperidine), Agnes can be assured that all these drugs have been evaluated well and that they are considered safe and acceptable to use in the fi rst few days after delivery. At this time, production of breast milk is increasingly rapidly, but the content is still changing from protein-rich colostrum, which is a poor transfer medium for most drugs, to fat-rich milk. Th e transfer of morphine and codeine, paracetamol, and NSAIDs into breast milk is only 2–4% of the weight- adjusted maternal dose, and none has adverse eff ects in the infant. Aspirin is not as good a choice as paracetamol/ acetaminophen, which has no detectable eff ects de- spite immature glucuronide conjugation. Aspirin is contraindicated in those at risk of bleeding due to its eff ect on platelet function, and although considered acceptable for use during lactation, it has been as- sociated with the rare and serious condition of Reye’s syndrome in newborns, so prolonged administration should be avoided. You should explain to Agnes that she should try to time her feeds to avoid the peak milk concentrations of the opioid she is taking, which will usually coincide with 1–2 hours after the last dose. What other methods might the city referral hospital be able to off er Agnes? Th ere may be a number of potentially superior meth- ods of postoperative pain relief at the referral hospi- tal that Agnes can consider and request. Intravenous morphine (and in some countries the metabolite-free but more expensive opioid fentanyl) provides better quality pain relief than subcutaneous or intramuscular morphine and is preferably administered using a pa- tient-controlled analgesia (PCA) device (standard set- ting, e.g., 1 mg bolus on demand, no continuous infu- sion, 5-minute lockout interval) to safeguard patients from unintentional overdosing. Neuraxial (spinal or epidural) opioid methods of analgesia provide better relief than intravenous, sub- cutaneous, intramuscular, or oral opioid administration. If spinal anesthesia is used, then intrathecal morphine 100–150 μg is a very safe and eff ective means of achiev- ing excellent pain relief. Morphine’s long elimination half-life in cere- brospinal fl uid results in clinically good or excellent pain relief for 4–24 hours (on average 12 hours), es- pecially if an oral NSAID is also given. Sedation, nau- sea, and vomiting are common side eff ects after opi- oids. In general, sedation will be greater after systemic administration (oral, intramuscular, and intravenous) and itch more severe after neuraxial (spinal or epi- dural) administration. All patients receiving opioids, especially neuraxial, should be monitored for overse- dation and low respiratory rate, although serious mor- bidity is rare in the obstetric population. Many hos- pitals and doctors appear especially concerned about spinal or epidural opioids, but when they are used correctly, case series suggest a signifi cantly higher risk of clinically important respiratory depression associ- ated with intravenous opioid. Postoperative epidu- ral analgesia is less likely to be available but is highly eff ective. It can be achieved with single or repeated (8–12 hourly) doses of morphine 3 mg or in technol- ogy-rich hospitals, with epidural infusion or patient- 240 Author(s) controlled epidural analgesia (PCEA) using fentanyl (2 μg bolus, 15 minute lockout time) or pethidine/me- peridine (20 mg bolus, 15 minute lockout time). Th ese epidural methods are associated with lower rates of opioid consumption (by 20–50%) than intravenous opioid and although short-term epidural opioid ad- ministration after cesarean delivery has not been well investigated, clinical experience suggests the breast- fed neonate is not aff ected. Immediate-release oxycodone (e.g., 5–10 mg regularly 4 hourly for 48 hours, with additional doses on request) is a more eff ective oral opioid than codeine and also tastes less unpleasant than oral morphine. Trama- dol (50–100 mg intravenous or oral, repeated 2 hourly to a maximum of 600 mg per day) is also an excellent choice for postoperative pain relief. Agnes can also be reassured that short-term use for a couple of days im- mediately postpartum is associated with low transfer of drug into breast milk (less than 3%) and that there are no apparent eff ects on the baby. In some countries the new generation of NSAIDs, the cyclooxygenase-2-spe- cifi c inhibitors (COX-2 inhibitors) such as intravenous parecoxib (40 mg daily) and oral celecoxib (400 mg then 200 mg 12 hourly) may be available, and because they have no eff ect on platelet function they are the best choice for women who are bleeding or at high risk of bleeding. However, they have not yet been adequately evaluated during human lactation, and although the risk of aff ecting the breastfeeding baby appears low, safety cannot be guaranteed. Some countries may also have in- travenous paracetamol/acetaminophen, which provides higher and more rapid peak plasma concentrations than an equivalent oral dose. Might any other local anesthetic blocks be useful in reducing Agnes’s risk of having poorly controlled pain? Wound infusion of local anesthetic (or perhaps even di- clofenac) is eff ective in reducing the dose of opioid need- ed, but it requires expensive pumps and wound cath- eters, so it is not likely to be available. If there is a doctor with suitable training, bilateral ilioinguinal and iliohypo- gastric blocks into the abdominal wall near the anterior iliac crest, or a rectus sheath block, can achieve similar opioid dose-sparing in the fi rst 12–24 hours. Th e best peripheral nerve block, if someone has the knowledge and expertise, would be for Agnes to receive bilateral transverse abdominis plane (TAP) blocks. Th is regional analgesic block is performed using, for example, 20 mL of 0.25% bupivacaine or 0.5% ropivacaine on each side. Th e injection is made just above the pelvic brim in the posterior section of the triangle of Petit, in the gap be- tween latissimus dorsi and the external oblique muscle. A “two-pop” (or in some countries ultrasound-guided) technique (as the blunt-tip needle passes through the external oblique fascial extension, then internal oblique fascia) allows local anesthetic to be deposited between the internal oblique and transverse abdominis muscles. Combined with oral analgesics, an eff ective TAP block covers the incision for cesarean delivery well (T10 to L1 dermatomes) and lasts up to 36 hours. Case report 3 (analgesics in later pregnancy) Th e nurse comes to tell you that Martine, a healthy woman in her fourth pregnancy at 33 weeks gestation who is attending the antenatal clinic, has been com- plaining of severe stabbing pain both at the back of her pelvis and low down at the front. Th e pain has been get- ting progressively worse for several weeks, and Martine can no longer care properly for her children. She fi nds it very painful to rise from a sitting position and is more comfortable crawling around the house on all four limbs than walking. When you see Martine, she explains that it took her 2 hours to walk from her house to the clinic, a journey that usually takes her 20 minutes. She is very tender to palpation over both the suprapubic region and upper buttocks. Th e pain is increased by “springing” the pelvis. “Please, is there anything that you can do to help me?”asks Martine. You explain that she appears to have symphysial diastasis with signifi cant separation and sec- ondary disruption and infl ammation at the sacroiliac joints. You explain the problem and discuss an initial plan of management with her. You tell her that she can start on some strong medications if she has not improved within a week. What sort of painful conditions occur during pregnancy? Diastasis of the pubic symphysis is an example of a very painful and disabling condition that frequently occurs during and after pregnancy. However, the principles of drug treatment for pain present after the fi rst trimes- ter of pregnancy can be applied to most painful condi- tions or diseases, including musculoskeletal pain (other examples are lumbar vertebral facet pain, disk protru- sion or rupture); visceral pain (cholecystitis, renal Chapter Title 241 colic, degenerating uterine fi broids, or bowel pain); neuropathic pain (intercostal neuralgia, meralgia par- esthetica of the lateral cutaneous nerve of the thigh, iliohypogastric and genitofemoral neuralgia, various cancer-induced neuralgias, post-traumatic complex regional pain syndrome, or post-amputation pain); migraine; and invasive cancer pain. What initial treatment would you suggest for Martine? Irrespective of the cause of the pain, nonpharmacologi- cal pain management options should be considered and tried, where possible, before analgesic drugs are used for acute pain that appears likely to require prolonged treatment or a stepwise approach to continued manage- ment. Your plan for Martine should start with physi- cal therapies (for example referral to a therapist for a sacroiliac pelvic support belt; gentle manipulation and postural exercises; and local application of heat or ice, transcutaneous electrical nerve stimulation, acupunc- ture or similar treatments), but it would also be reason- able to introduce nonopioid analgesic drugs, bearing in mind their safety for the fetus and neonate. Paracetamol (acetaminophen) has been used in millions of pregnant women and is safe. Aspirin is acceptable, but its pro- longed use is best avoided (see case 2 above). Tramadol has not been evaluated in large trials during pregnancy but is widely used after the fi rst trimester, so it would be acceptable for short-term use for Martine to reduce the severe pain until other measures have had a chance to become eff ective. It would not be ideal to continue tra- madol for several weeks until the time of delivery, be- cause a neonatal withdrawal syndrome at 24–36 hours has been reported. NSAIDs have a limited role during pregnancy, and it is very important to understand the implications of prescribing them. Th ese drugs prevent prostaglan- din-induced myometrial gap junction formation and transmembrane infl ux and sarcolemmal release of cal- cium, making indomethacin an eff ective tocolytic drug that has been used to prevent preterm labor after the period of organogenesis. However, they are contrain- dicated in later pregnancy, certainly after 32 weeks gestation (as applies to Martine), and some would ar- gue from the start of fetal viability (23–24 weeks in re- source-rich countries and hospitals). Th is leaves only a short period during the second trimester of pregnancy when these drugs may be useful. Fetal exposure in late pregnancy may result in oligohydramnios due to renal impairment, premature closure of the ductus arterio- sus with subsequent neonatal pulmonary hyperten- sion, and neonatal intracranial hemorrhage. Th ere is insuffi cient information about the eff ects of the COX-2 inhibitors (e.g., celecoxib), so these agents should also be avoided. Would local anesthetics or opioid drugs be suitable in this case? It is the case with many painful conditions (including Martine’s) that the treatment you start with ultimate- ly proves insuffi cient. Th e possibility of a neuropathic component should be considered in Martine’s case, and the appropriate drug treatment is discussed in case 1 above. However, the two main options to consider next for Martine are local anesthetic infi ltration and oral opioid analgesia. Infi ltration with local anesthetic pro- vides temporary (and sometimes prolonged) relief of joint pain (another example is into the coccyx for coc- cydynia, or into the facet joint for back pain) and myo- fascial pain (for example into trigger points in the ab- dominal wall, neck, or shoulders or the costochondral and intercostal area). A steroid such as triamcinolone could be included if infl ammation is suspected, but steroids are best omitted in the fi rst trimester and in repeated injections. Provided the operator has knowl- edge of the relevant anatomy and adequate expertise, infi ltration is generally a low-risk procedure that can be useful both diagnostically and therapeutically. Th e local anesthetic drugs are of no or minimal risk to the fetus, although maximum dose limits for the individu- al drug and the type of block should be applied. Extra care must be taken when injecting near major organs or the fetus (for example, when injecting near the blad- der and lower uterine segment or cervix at the pubic symphysis). As a fi nal option, if epidural techniques are available in a referral hospital, a period of epidural an- algesia with a combined local anesthetic and opioid can be very benefi cial. If opioid analgesia is commenced during pregnancy, it would be best to arrange inpatient care for a few days. This strategy allows oral opioid titra- tion and stabilization (see case 1 above) and supple- mentation with intravenous opioid or intravenous ketamine to establish pain control. Oral or sublingual opioids (morphine, methadone, codeine, and in some countries oxycodone, buprenorphine, and fentanyl) can be used safely for short periods during pregnancy (and in some cases will already be prescribed or are 242 Author(s) being used by patients illicitly). If prolonged admin- istration is expected, drugs without active metabo- lites are preferable, for example methadone rather than morphine for maintenance therapy in opioid ad- dicts. Although there is a slightly higher rate of low birth weight and stillbirth among women on chronic opioid therapy, the majority have good neonatal out- comes. It has been suggested that chronic opioid use in pregnancy is associated with addictive behavior in later adult life, but observational evidence does not prove causality, and such findings should be viewed with some scepticism. Women who become opi- oid tolerant and need escalating doses will provide a number of challenges in managing pain during labor, as well as during and after cesarean section. Options such as opioid rotation and multiple opioids may need to be considered (see chapter on chronic opioid therapy). These women need more interventions and increase the staff workload. The neonatal effects of opioid analgesics be- ing used at the time of childbirth are important, so a number of staff need to be aware of opioid con- sumption, including the obstetrician, midwife, pe- diatrician, and local doctor. Neonatal respiratory de- pression may be present at birth, so staff skilled in neonatal resuscitation may be required; if possible, naloxone should be available. Also, the baby should be observed in a high-dependency care area if possi- ble, and staff trained to watch for neonatal withdraw- al/neonatal abstinence syndrome. This syndrome usually commences in the hours or days following birth (depending on the half-life of the specific opi- oid, i.e., 6–36 hours for morphine and 24–72 hours for methadone and buprenorphine), but it is occa- sionally delayed for several days. The risk is greatest if the mother has become opioid-tolerant and has needed an escalation dose or high maintenance doses (30–90% incidence with long-term methadone use and 50% incidence, but less severe, with buprenor- phine maintenance therapy). Unfortunately, breast- feeding does not prevent the syndrome. The signs and symptoms in the baby are due to autonomic overactivity (which can manifest as yawning, sneez- ing, or fever) and cerebral irritability (for example tachypnea, tremor, increased tone, poor feeding be- havior, and in severe cases, seizures). The severity of the syndrome also correlates partly with the maternal dose, so is most severe in opioid-tolerant or addicted women. The baby should be swaddled and nursed in a quiet environment, and some will need treatment with sedative drugs such as phenobarbitone (10 mg/day), di- azepam, clonidine, or morphine (starting at 0.4–1.0 mg/ day in divided doses and increasing 10–20% every 2–3 days as needed). Treatment may need to be continued for 4–20 days and sometimes much longer. Download 4.8 Kb. Do'stlaringiz bilan baham: |
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