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PAIN MANAGEMENT IN THE OBSTETRIC PATIENT 

EPIDURAL ANALGESIA

Continuous epidural infusion with LA has many advantages over intermittent bolus injection epidural, spinal anesthesia, anesthesia in labor. It maintains a stable level of analgesia and reduces the need for bolus injections. Hemodynamic disturbances are thus reduced, and fetal and neonatal outcome are improved. The risks of infection and intrathecal and intravascular migration of the epidural catheter are reduced, and safety is increased epidural, spinal anesthesia, anesthesia in labor. A combination of LA and epidural opioids produces good analgesia with rapid onset and longer duration of action and fewer side effects than LA alone. Parturients receiving epidural infusions of LA and opioids receive less bupivacaine, with reduced motor block at delivery. Continuous epidural infusion of bupivacaine is safe and does not cause hemodynamic changes or result in accumulation of LA in the mother or fetus.

The most commonly used LA is bupivacaine, at a standard concentration of 0.25% for bolus injections with an infusion of 0.125%, with fentanyl as the opioid at a rate of 8 to 12 mL/hr. Pain varies among parturients, so the bolus injections and rate of infusion must be varied greatly for adequate pain relief. Recent literature suggests an increased incidence of instrumental delivery rate related to epidural use in laboring women, but this conclusion is disputed. The result of this debate has been a surge of interest in the use of dilute concentrations of LA with opioids. Ultra-low concentrations of bupivacaine with opioids have been used with resulting good pain relief. These low concentrations produce minimal or no motor block and let the mother remain able to walk. Sufentanil with

Carefully titrated continuous epidural analgesia to a T10 sensory level provides satisfactory analgesia for labor and delivery. Epidural analgesia with appropriate monitoring would be useful for labor analgesia in most critically ill parturients providing there are no contraindications to placement of an epidural catheter. Uterine displacement must be maintained at all times to avoid aortocaval compression. Decreases in blood pressure must be corrected with

INTRATHECAL OPIOIDS

When compared with LA, spinally administered opioids produce selective analgesia. Intrathecal opioids do not produce motor block, sympathectomy, hypotension, or adverse effects on uterine contractility. When given in small doses, they produce no adverse fetal or neonatal effects. Intrathecal morphine (0.5-2.0 mg) has been shown to provide good analgesia in the early first stage of labor, which lasts up to 11 hours. It takes 30 to 60 minutes for the parturient to experience significant pain relief with intrathecal morphine, and side effects can last for more

Side Effects

Side effects of intrathecal fentanyl and intrathecal sufentanil appear to be mild and do not require treatment. Intrathecal sufentanil, being more potent and lipid soluble than intrathecal fentanyl, can cause respiratory depression and apnea, and the parturient should be monitored carefully for at least 1 hour after injection. Intrathecal

COMBINED SPINAL-EPIDURAL ANALGESIA

A combined spinal-epidural (CSE) anesthesia technique provides rapid onset of analgesia with drugs administered via a small-gauge pencil-point spinal needle into the intrathecal space. An epidural catheter placed simultaneously provides flexibility of epidural analgesia. Pain relief can be provided later with the epidural catheter when the

CONTINUOUS SPINAL ANALGESIA

The development of small-bore catheters produced an interest in continuous spinal analgesia techniques for labor. The catheter overcomes some of the drawbacks of single opioid injections. Reports of cauda equina syndrome after widespread use of small-gauge spinal catheters led to withdrawal of the catheter from the market in 1992 by the

PATIENT-CONTROLLED EPIDURAL ANALGESIA

Pain varies greatly among parturients during labor and even within the same parturient during the course of labor. Some parturients like to participate more actively in all aspects of intrapartum care, including pain relief. The advantages of patient-controlled epidural analgesia (PCEA) are control of pain relief by the parturient to her own

PATIENT-CONTROLLED INTRAVASCULAR ANALGESIA

An apparatus for patient-controlled intravascular analgesia (PCIA) in labor has been shown to be successful and safe. The goal of PCIA is to produce a relatively stable blood level by allowing the patient to give multiple frequent small bolus doses of narcotic, after an initial loading dose. Patient-controlled intravascular analgesia with meperidine and nalbuphine produces satisfactory analgesia and reduces the consumption of systemically administered opioid. Nalbuphine produces good pain relief in labor when compared with meperidine, and fentanyl appears to be better

NEW DRUGS

Stimulation of alpha₂ adrenoreceptors by epinephrine and clonidine in the spinal cord produces analgesia. Therefore, epidurally administered epinephrine and clonidine have the potential to produce segmental analgesia. Clonidine produces hemodynamic disturbances and sedation, and this drug is 

Neostigmine, a cholinesterase inhibitor, potentiates the analgesic effect of acetylcholine in the spinal cord dorsal horn in response to painful stimulus. Intrathecal neostigmine has been used in labor but provides little labor

POSTOPERATIVE PAIN RELIEF

Effective analgesia after cesarean section must maintain the patient's ability to walk and avoid significant sedation, to allow the mother to interact with the newborn. Intramuscular analgesics have traditionally been used, but these cause undue sedation and do not provide adequate analgesia. Patient-controlled intravascular analgesia allows patients to titrate the opioids as necessary, achieving good analgesia and maintaining steady plasma levels as

COAGULOPATHY AND CENTRAL NERVOUS BLOCKADE

Some critically ill parturients develop coagulopathy or may be on anticoagulants such as heparin. It is important to examine the complications of central neural blockade in the presence of coagulopathy and anticoagulants.

Spinal hematomas are rare complications of spinal or epidural anesthesia. Acute spinal cord compression from a hematoma in the epidural, subdural, or subarachnoid space can rapidly produce permanent paraplegia. In most

Disseminated Intravascular Coagulation

Disseminated intravascular coagulation (DIC) is the result of abnormal activation of the coagulation cascade, leading to formation of thrombi, depletion of coagulation factors, activation of the fibrinolytic system, and hemorrhage. The disorders associated with DIC can be due to release of procoagulant-like material into the circulation or due to

Anticoagulation Therapy

Warfarin is not used during pregnancy because of the risk of teratogenicity in early pregnancy and the risk of central nervous system abnormalities in the second and third trimesters. Heparin is the 

PAIN RELIEF FOR NONOBSTETRIC PROBLEMS

Pregnancy is associated with physiologic changes that can affect the pharmacokinetics of drugs. These effects are caused by alteration in the activity of drug metabolizing enzyme systems, excretion, secretion and transport process, changes in body composition, and alteration of protein binding. Most of the medications that are used during pregnancy reach the fetus to some degree, with the exception of highly charged polar compounds such as heparin.

Exposure to certain drugs during the most critical period of organogenesis, during days 31 to 71 after the last menstrual period, can result in malformations. The long-term effect of drug exposure in utero may not become apparent for many years, and drug use should be reduced or postponed during pregnancy. When possible, drug therapy should be avoided, or the minimum dose should be used, and parturients should be educated about

Pain Relief in Sickle Cell Disease

Management of pain during vasoocclusive crisis is mainly supportive and symptomatic. Understanding the factors that precipitate sickle cell crisis and its pathophysiology is essential in management of these patients. Rehydration, correction of acidosis, oxygen, treatment of infection, pain management, and transfusion to reduce sickle cell

CARDIAC DISEASE AND PREGNANCY

Acquired heart disease such as rheumatic heart disease is uncommon in young women but with advances in medical care those with congenital heart disease survive to reproductive age. Problems in the pregnant woman with cardiac disease are due to normal physiologic changes that occur during pregnancy.

Pregnant cardiac patients with symptoms of right or left ventricular failure and asymptomatic patients need effective analgesia and invasive hemodynamic monitoring during labor and delivery. Management of the patient is based on

Pulmonary Hypertension

Whatever the cause, pulmonary hypertension carries a very poor prognosis during pregnancy. Maternal mortality is 30% to 50% during labor and in the peripartum period. Many authors suggest that women with pulmonary hypertension avoid pregnancy and advise therapeutic abortion in early pregnancy. Hemodynamic changes include mean pulmonary pressure in excess of 25 mm Hg, right ventricular hypertrophy, and eventually, heart failure with a low fixed cardiac output. In patients with Eisenmenger's syndrome the decrease in systemic vascular resistance

Mitral Stenosis

Mitral stenosis in pregnancy is an acquired condition commonly due to rheumatic heart disease. The main hemodynamic disturbance is obstruction of left ventricular diastolic filling, resulting in fixed cardiac output. Decreased emptying of the left atrium results in increased left atrial and pulmonary artery pressures, resulting in dyspnea, hemoptysis, and pulmonary edema. Progressive pulmonary hypertension leads to right ventricular hypertrophy and right ventricular failure. Cardiac output in patients with mitral stenosis depends on two factors, diastolic filling time and left ventricular preload. Tachycardia of any cause can limit diastolic filling and increase left atrial and pulmonary arterial pressures and pulmonary edema in these patients. Therefore, tachycardia due to

Aortic Stenosis

The major problem associated with aortic stenosis is a limited ability to compensate for the cardiovascular demands of pregnancy. Patients with severe disease will be symptomatic with angina, myocardial infarction, dyspnea, syncope, or sudden death. The maintenance of cardiac output is essential; any factor that diminishes preload will cause an  

Myocardial Infarction

Myocardial infarction is uncommon in pregnant women. The incidence of myocardial infarction is less than 1:10,000, according to Ginz. The prognosis after infarction is significantly worse in late pregnancy, with an overall mortality rate of 40% to 50% in the third trimester.  According to a review by Hankins et al, delivery within 2 weeks of

Peripartum Cardiomyopathy

Peripartum cardiomyopathy, with an incidence of approximately 1 in 3000 to 4000, occurs during the last month of the pregnancy or more