Cardiac output may decrease when patients are in the supine position but not in the lateral decubitus position. It is prudent to delay surgery, when possible, until after the birth of the infant. In parturients with “heartburn,” the lower esophageal sphincter tone is greatly reduced. This has been attributed to an EDTA-induced leaching of calcium from paravertebral muscles. The rates of distribution, metabolism, and excretion of the drug, which may vary, are equally important. Abruptio placentae occurs in 0.2–2.4% of pregnant women, usually in the final 10 weeks of gestation and in association with hypertensive diseases. The pKa (acid dissociation constant) is the pH at which the concentrations of free base and cation are equal. The pudendal nerves are derived from the lower sacral nerve roots (S2–4) and supply the vaginal vault, perineum, rectum, and sections of the bladder. The placental transfer of an active metabolite, normeperidine, which has a long elimination half-life in the neonate (62 hours), has also been implicated in contributing to neonatal depression and subtle neonatal neurobehavioral dysfunction. In contrast, 2-chloroprocaine, an ester local anesthetic, undergoes rapid enzymatic hydrolysis in the presence of pseudo-cholinesterase. This educational activity may contain discussion of published and/or investigational uses of agents that are not indicated by the FDA. Although paracervical block effectively relieves pain during the first stage of labor, it is now rarely used in the United States because of its association with a high incidence of fetal bradycardia, particularly with the use of bupivacaine. Before inducing epidural blockade, it should be ascer-tained that the fetus is neither hypoxic nor acidotic. Thus, greater hemodynamic stability may be observed with epidural anesthesia, where gradual titration of local anesthetic allows for better control of the block level as well as for adequate time for vasopressor administration in anticipation of blood pressure reduction. The absorption rate can vary with the site of injection. The implementation of general anaesthesia (4), combined spino-epidural anaesthesia (5), epidural anaesthesia (6), and continuous spinal anaesthesia (7) in pregnant women with PAH has been reported . Regardless, increased alveolar ventilation occurring during pregnancy actually leads to a reduction in the partial pressure of carbon dioxide in arterial blood (PaCO2) to 32 mm Hg and an increase in the partial pressure of oxygen in arterial blood (PaO2) to 106 mm Hg. Epidural or spinal hematoma is a rare complication of neuraxial anesthesia in pregnant women 85 and is seen most often in patients with a known coagulopathy. Consumption coagulopathy may require infusion of fresh whole blood, platelet concentrates, fresh frozen plasma, and cryoprecipitate. The addition of epinephrine 15 mcg with careful continuous heart rate and blood pressure monitoring may herald intravascular injection with a transient increase in heart rate and blood pressure. A shortening of the PR and QT intervals and an increase in heart rate are also present. Paravertebral lumbar sympathetic block is a reasonable alternative to central neuraxial blockade. Many of the symptoms associated with preeclampsia, including placental ischemia, systemic vasoconstriction, and increased platelet aggregation, may result from an imbalance between the placental production of prostacyclin and thromboxane. Transient nonreassuring fetal heart rate patterns may occur because of uterine hyperstimulation, presumably as a result of a rapid decrease in maternal catecholamines resulting in the unopposed effects of oxytocin. The following maneuvers are useful to rule out the pos-sibility of high neuraxial anesthesia: Systolic blood pressure consistently more than 15% above baseline, Diastolic blood pressure consistently more than 15% above baseline. The patient’s ability to handle a glucose load is decreased, and the transplacental passage of glucose may stimulate fetal secretion of insulin, leading, in turn, to neonatal hypoglycemia in the immediate postpartum period. A recent study demonstrated that a pudendal nerve block does not provide reliable analgesia for the second stage of labor, probably related to the upper vagina being innervated by lumbar, rather than sacral, fibers. Prematurity (gestation of less than 37 weeks), postmaturity (gestation of 42 weeks or longer), intrauterine growth retardation, and multiple gestation are fetal conditions associated with risk. demonstrated that increased sFlt-1 levels and reduced PlGF levels predicted the subsequent development of preeclampsia. During normal pregnancy, the placenta produces equal amounts of the two, but in a preeclamptic pregnancy, there is seven times more thromboxane than prostacyclin. 86 Almost all anesthesiologists will initiate neuraxial anesthesia if the platelet count is more than 100,000/mm 3. Peripheral nerve injury as a result of instrumentation, lithotomy position, or compression by the fetal head may occur even in the absence of neuraxial technique. Levine et al. The use of levobupivacaine compared to racemic bupivacaine has been demonstrated to result in fewer fetal bradycardias. Some tumours such as meningiomas may express oestrogen or progesterone receptors and as such rapidly increase in size in the pregnant state. Coagulation factors I, VII, VIII, IX, X, and XII increase during pregnancy, whereas factor XI and XIII concentrations decrease and factor II and V concentrations remain unchanged during pregnancy. Lidocaine has an onset and duration intermediate to those of 2-chloroprocaine and bupivacaine. However, with the prolonged administration of highly protein-bound drugs, such as bupivacaine, substantial accumulation of drug can occur in the fetus. The HELLP syndrome is a particular form of severe preeclampsia characterized by hemolysis, elevated liver enzymes, and low platelets. showed that women who received lumbar sympathetic blocks had a more rapid rate of cervical dilatation during the first two hours of analgesia and a shorter second stage of labor compared to epidural analgesia. The space between either the second and third or the third and fourth lumbar vertebrae was used. However, the half-life was longer in the newborn; this is related to a greater volume of distribution and tissue uptake, so that, at any given moment, the neonate’s liver and kidneys are exposed to a smaller fraction of lidocaine accumulated in the body. Most studies have demonstrated that the incidence of emergency cesarean section delivery is no greater with CSE analgesia than after conventional epidural analgesia. Gastric secretions are more acidic, and lower esophageal sphincter tone is decreased. In another study, alfentanil PCA failed to provide adequate analgesia compared to fentanyl PCA. The choice of anesthetic for a woman with placental abruption depends on maternal and fetal condition and how urgently the procedure needs to be performed. Laparoscopic surgery during pregnancy. This injury occurs as a result of reduced placental perfusion, leading to a production and release of substances (possibly lipid peroxidases) causing endothelial cell injury. The goals of anesthesia during pregnancy are to ensure recovery of the mother and normal continuation of the pregnancy without damage to the fetus. The pathogenesis may be due to a weakened epidural vascular architecture. A potential disadvantage is a high incidence of maternal sedation. However, there is less room for error because many of these functions may be compromised before the induction of anesthesia. Catheter aspiration alone is not always diagnostic. Fetal bradycardia and death may ensue. Rapid injection of 1 mL of air with simultaneous precordial Doppler monitoring appears to be a reliable indicator of intravascular catheter placement. Similar results have been reported in another study involving lidocaine administration to human infants in a neonatal intensive care unit. In severe cases or if the fetus is mature at the onset of symptoms, prompt delivery is indicated, usually by cesarean section. Regional analgesia can benefit the fetus by eliminating maternal hyperventilation with pain, which often leads to a reduced fetal arterial oxygen tension owing to a leftward shift of the maternal oxygen–hemoglobin dissociation curve. The most frequently chosen methods for relieving the pain of parturition are psychoprophylaxis, systemic medication, and regional analgesia. Postgraduate Institute for Medicine is jointly accredited by the Accreditation Council for Continuing Medical Education (ACCME), the Accreditation Council for Pharmacy Education (ACPE), and the American Nurses Credentialing Center (ANCC), to provide continuing education for the healthcare team. Leighton et al. The residual volume and FRC return to normal shortly after delivery. However, butorphanol use was associated with fewer maternal side effects, such as nausea, vomiting, and dizziness, than meperidine. The severe manifestation of the disease occurs in approximately 1:10.000 cases (8). Facts About the Spinal Block Procedure. II. Recent studies do not support the administration of corticosteroids or lung lavage with saline and bicarbonate to neutralize acidity. Note: For more information on thrombocytopenia in pregnancy including etiologies and management, see ‘Related ObG Topics’ below, Neuraxial Anesthesia: Thrombocytopenia-Related Spinal Henatoma, We found no evidence from RCTs or non‐randomised studies on which to base an assessment of the correct platelet transfusion threshold prior to insertion of a lumbar puncture needle or epidural catheter, …clinicians and patients should engage in shared decision-making about the perceived competing risks/benefits of proceeding with or withholding neuraxial anesthesia in cases of severe thrombocytopenia and concurrent aspirin use, The Society for Obstetric Anesthesia and Perinatology Interdisciplinary Consensus Statement on Neuraxial Procedures in Obstetric Patients with Thrombocytopenia, SOAP Thrombocytopenia Consensus Statement FINAL, Cochrane Review: Use of platelet transfusions prior to lumbar punctures or epidural anaesthesia for the prevention of complications in people with thrombocytopenia, Already an ObGFirst Member? It has been suggested that meperidine administration may prolong the latent phase of labor but shorten the cumulative length of the first stage of labor. For that reason, some authors believe that a test dose should be administered to improve detection of an intrathecally or intravascularly placed epidural catheter. However, a recent study showed no benefit to the administration of meperidine in order to possibly shorten the first stage of labor in women having dystocia. However, there was no difference in the rate of dilatation during the active phase of labor. Pregnancy results in significant changes affecting most maternal organ systems (Table 1). This has led some clinicians to avoid the use of lidocaine for intrathecal administration (see “Systemic Toxicity of Local Anesthetics” below). This angiogenesis is a result of the trophoblast invasion into the decidual and myometrial segments of the spiral arteries. The relatively smaller increase in red blood cell volume (20%) accounts for a relative reduction in hemoglobin (to 11–12 g/L) and hematocrit (to 35%); the platelet count, however, remains unchanged. Nerve root irritation may have a protracted recovery, lasting weeks or months. In addition, epinephrine may potentially reduce uteroplacental perfusion in some patients. It has been demonstrated that for effective prevention of hypotension, the blood volume increase from preloading must be sufficient to result in a significant increase in cardiac output. Smaller doses of local anaesthetic are needed for spinal anaesthesia in pregnancy, and the spread in cerebrospinal fluid (CSF) is less . Other side effects are nausea and vomiting, dose-related depression of ventilation, orthostatic hypotension, the potential for neonatal depression, and euphoria out of proportion to the analgesic effect, leading to misuse of the drug. It combines the rapid, reliable onset of profound analgesia resulting from spinal injection with the flexibility and longer duration of epidural techniques. All identified COI are thoroughly vetted and resolved according to PIM policy. Plasma volume expansion combined with vasodilation fulfills these goals. Antihypertensive therapy in preeclampsia is used to lessen the risk of cerebral hemorrhage in the mother while maintaining, or even improving, tissue perfusion. These changes may be progressive during the course of gestation and are often difficult to predict for an individual drug. Apart from trauma, the most common emergencies are abdominal, intracranial aneu-rysms, cardiac valvular disease, and pheochromocytoma. This technique is most useful for multiparous parturients who are rapidly progressing in labor and require analgesia or anesthesia of short duration before complete cervical dilation and anticipated vaginal delivery or in settings in which continuous epidural analgesia is not possible. Nonetheless, it would seem prudent to avoid general anesthesia in preference for regional techniques during pregnancy because of the maternal and fetal considerations previously discussed. Studies have shown preloading with crystalloid does not reliably prevent neuraxial anesthesia–induced hypotension. on the safe administration of neuraxial anesthesia to a pregnant patient with an implanted spinal cord stimulator, particularly a thoraco-lumbar stimulator. It also means the mother is conscious and the partner is able to be present at the birth of the child. Epidural anaesthesia (local anaesthetic during pregnancy) is used during delivery for labour analgesia. This causes a larger total amount of local anesthetic to accumulate in the fetal plasma and tissues. In the presence of severe clotting abnormalities or severe plasma volume deficit, the risk–benefit ratio favors other forms of anesthesia. In the case of most anesthetic agents, these changes are minor and transient, lasting for only 24–48 hours. The anesthetic numbs the area below the point of injection as well as the legs, and allows you to remain awake during the delivery. However, it may also induce unac-ceptable amnesia that may interfere with the mother’s recollection of the birth. Regional anesthesia can be success-fully used, with nitroglycerin available for uterine relaxation if needed. Cardiovascular changes and pitfalls in advanced pregnancy include the following: Increase in heart rate (15%–25%) and cardiac output (up to 50%). Repeat spinal anesthesia after a failed spinal block in a pregnant patient with kyphoscoliosis for elective cesarean section Rakesh Kumar, Kunal Singh, Ganga Prasad, Nishant Patel Department of Anaesthesiology and Intensive Care, All India Institute of Medical Sciences, New Delhi, India There are few data to guide medical decision making, but altering the type of surgical technique (eg, converting from laparoscopic to open appendectomy) should be entertained in order to facilitate the use of regional anesthesia. Studies have shown that PCEA with a relatively low continuous epidural infusion and top-ups required fewer anesthetic interventions compared to PCEA without a basal rate epidural infusion. However, hypotension and sedation have been reported with spinal clonidine and may limit its routine use. Pregnancy and parturition are considered high risk when accompanied by conditions unfavorable to the well-being of the mother or fetus, or both. Initial analgesia is achieved with bolus doses of local anesthetic. Friability of the mucous membranes during pregnancy can cause severe bleeding, especially on airway instrumentation. Result: The incidence of spinal anesthesia-induced hypotension was higher in non-preeclamptic parturients than preeclamptic parturients (55.6% vs. 34.1%, respectively) and the degree of blood . Severe complications, such as respiratory distress syndrome, intracranial hemorrhage, hypoglycemia, hypocalcemia, and hyperbilirubinemia, are prone to develop in preterm infants.Obstetricians frequently try to inhibit preterm labor to obtain time for fetal lung maturity. Spinal anaesthetic. The medication is fast acting and can achieve a complete block of pain in as little as 2-3 minutes. The most commonly used local anesthetic agents are 2-chloro-procaine 3%, bupivacaine 0.5%, and lidocaine 2% with epinephrine 1:200,000. With the development of newer needles and bevel designs and methods whereby the incidence of hypotension can be minimized, spinal anaesthesia is making a reappearance in obstetrical anaesthesia spheres. The panel was convened to address an ongoing issue where obstetric patients with thrombocytopenia are often denied neuraxial anesthesia due to risk of spinal epidural hematoma. Although spinal anaesthesia is the most commonly used method of providing surgical anaesthesia for elective caesarean delivery, spinal hypotension can commonly occur in up to 70% of patients . demonstrated that the incidence of cesarean section delivery was no different in nulliparous women having epidural analgesia initiated during the latent phase (at 4 cm dilation) compared with women whose analgesia was initiated during the active phase. The reduced epidural pressure increases the risk of cerebrospinal fluid leakage through the dural opening. Labor pain, a form of acute pain, is perceived by many women as very severe or intolerable. Regarding neuraxial anesthesia for a patient with a history of scoliosis: a. Neuraxial anesthesia is contraindicated due to the high risk of neurologic damage b Surgical correction of scoliosis presents additional challenges c. Epidurals have been shown to be more effective in providing an adequate block than a single shot spinal d. These changes are caused by increased extracellular fluid and vascular engorgement. Rather than a specific blood pressure elevation, a blood pressure that is consistently 15% above baseline is now considered diagnostic. In addition, motor block may be uncomfortable for some women and may prolong the second stage of labor. Hypotension resulting from sympathectomy is the most common complication that occurs with central neuraxial blockade. Even with an adequate dermatomal level for surgery, women undergoing cesarean section may experience discomfort, particularly during exteriorization of the uterus and traction on abdominal viscera. The QT interval shortening may have implications for women with long QT syndrome. In the presence of maternal tachycardia, phenylephrine 25–50 mcg may be substituted for ephedrine in women with normal uteroplacental function. A spinal block is a spinal anesthesia often called a "spinal." In this procedure, a narcotic or anesthetics such as fentanyl, bupivacaine or lidocaine is injected below the spinal column directly into the spinal fluid, which provides pain relief for as long as 2 hours. It can be administered by IV injection (effective analgesia in 5–10 minutes) or intramuscularly (peak effect in 40–50 minutes). Spinal anesthesia is a safe technique, widely used and tested in the gynecological field, so as to be considered the first choice technique in cesarean section, which allows to quickly obtain a valid sensor and motor block. In support of improving patient care, this activity has been planned and implemented by the Postgraduate Institute for Medicine and The ObG Project. Note that organogenesis occurs from 15-56 days of gestation. Jason Choi, Liane Germond, and Alan C. Santos. spinal. A study of anesthesia-related deaths in the United States between 1979 and 1990 showed that the case fatality rate with general anesthesia was 16.7 times greater than that with regional anesthesia. Spinal anaesthesia uses a very thin needle that is placed in the spine where the spinal fluid is located. The anesthetic management should be the same as for the nonpregnant patient with an aneurysm, except that a pregnant patient is actually two . conducted a prospective cohort study that showed the risk of significant spinal anesthesia–induced hypotension was significantly lower in preeclamptic women compared to normotensive pregnant women. Advances in regional anes-thesia and its widespread routine use have resulted in significantly enhanced maternal safety compared with that of general anesthesia. In countries outside the United States, intermittent nitrous oxide has been used for labor analgesia. Experience with the newer synthetic opioids, such as fentanyl and alfentanil, has been limited. One common side effect of spinal anesthesia is maternal hypotension, or low blood pressure (sometimes this is also referred to as a hypotensive crisis).Maternal hypotension may cause nausea and vomiting in the mother . Significant hypotension is more likely to occur in pregnant versus nonpregnant women undergoing regional anesthesia, necessitating uterine displacement or lateral pelvic tilt maneuvers, intravascular preloading, and vasopressors. Alternatively, the epidural component may be activated when necessary. However, it has been questioned whether ropivacaine produces spinal anesthesia of similar quality to that of bupivacaine. This chapter focuses on the management of obstetric patients with a primary focus on regional anesthesia techniques. A randomized controlled trial of preinsertion ultrasound guidance for spinal anaesthesia in pregnancy: outcomes among obese and lean parturients: ultrasound for spinal anesthesia in pregnancy J Anesth. If hypotension occurs despite these measures, left uterine displacement should be increased, the rate of IV infusion augmented, and IV ephedrine 5–15 mg (or phenylephrine 25–50 mcg) administered incrementally. The origin of preeclampsia-eclampsia is unknown, but all patients manifest placental ischemia. After epidural injection, the mean half-life in the mother is approximately 3 minutes; after reinjection, 2-chloroprocaine can be detected in the maternal plasma for only 5–10 minutes, and no accumulation of this drug has occurred. Unless the lowest placental edge is more than 2 cm from the internal cervical os, an abdominal delivery is usually required. The premature infant is known to be more vulnerable than the term newborn to the effects of drugs used in obstetric analgesia and anesthesia. The experimental evidence on exposure to specific drugs and agents is discussed briefly, with the understanding that it is difficult to extrapolate laboratory data to the clinical situation in humans. Decreased placental per-fusion occurs in early pregnancy in women destined to become preeclamptic, and there is a failure of the normal trophoblastic invasion. The mainstay of anticonvulsant therapy in the United States is magnesium sulfate. Spinal anaesthetic - this is the most common; Epidural - you might have your epidural topped up if you've had one for labour; Spinal anaesthetic and epidural together; More about epidurals. Maternal acceptance is excellent, and demands on anesthesia manpower may be reduced. The planners of this activity do not recommend the use of any agent outside of the labeled indications. The most recent formulation of 2-chloroprocaine contains no additives and is packaged in an amber vial to prevent oxidation. By reducing the maternal secretion of catecholamines, epidural analgesia may convert a previously dysfunctional labor pattern to a normal one. In a recent double-blind trial, remifentanil PCA was compared to lumbar epidural for equivalent analgesia. In one study, Apgar and neurobehavioral scores were good in neonates whose mothers were given an IV infusion of remifentanil, 0.1 mcg/kg/min, during cesarean section delivery under epidural anesthesia. Before caudal injection, a digital rectal examination must be performed to exclude needle placement in the fetal presenting part. The diagnosis of abruptio placentae is based on the presence of uterine tenderness, hypertonus, and vaginal bleeding of dark, clotted blood. The most common side effects of intrathecal opioids are pruritus, nausea, vomiting, and urinary retention. found a reduced risk (risk ratio [RR] = 0.38) of cardiac events during pregnancy in woman with prolonged QT syndrome. Epidural and Spinal Anesthesia During Labor. Although preeclampsia is accompanied by exaggerated retention of water and sodium, the shift of fluid and proteins from the intravascular into the extravascular compartment may result in hypovolemia, hypoproteinemia, and hemoconcentration, which may be further aggravated by proteinuria. The use of epidural anesthesia increases the risk of vacuum- or forceps-assisted vaginal delivery. The ultrasound imaging technique can be a reliable guide to facilitate spinal anesthesia, especially in obese parturients. Dr Graham Hocking Consultant in Anaesthesia and Pain Medicine, John Radcliffe Hospital, Oxford, UK Email: ghocking@btinternet.com This tutorial will detail the factors that determine how local anaesthetic spreads within the CSF therefore determining the extent of the block.
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