OB Anesthesia Management – Flashcards
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When is ketamine used for cesarean section? Specify the ketamine dose.
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Ketamine is used instead of thiopental if the mother is hypovolemic. Ketamine at doses of 0.2-0.5 mg/kg IV produce excellent analgesia for labor and delivery. [Morgan and Mikhail, Clinical Anesthesiology, 1996, pp711, 714; Barash Handbook, Clinical Anesthesia, 1997, p 1067; Stoelting, PPAP, 1995, pili J
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What is the maximum dose of ketamine to be used on a pregnant woman during a rapid sequence induction? What happens with larger doses?
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The maximum dose of ketamine for rapid sequence induction of a pregnant women is 1 mg/kg. Above this dose, uterine tone increases enough to endanger the fetus. [Barash, Clinical Anesthesia, 1997, p1067J
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What is the major concern for a patient who is sched uled for tubal ligation in the early post-partum period?
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The major concern is aspiration. [Stoelting, Co-Existing, 1993, p575; Stoelting and Miller, Basics, 1994, p378]
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How can the risk of aspiration be reduced in the patient who is scheduled for tuballigation in the early post-partum period?
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The risk of aspiration is diminished if the surgery was anticipated and continuous epidural analgesia or spinal was used. When regional anesthesia has not been used, wait 8-12 hours post-part urn to allow the patient to reach cardiovascular stability and increase the likelihood of gastric emptying. Give antacids or H2 antagonists. [Stoelting, Co-Existing, 1993, p575; Stoelting and Miller, Basics, 1994, p378]
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What are 5 major anesthetic concerns for the pregnant patient scheduled for nonobstet ric surgery?
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Five major concerns for the pregnant patient scheduled for nonobstetric surgery are: (1) maternal safety, (2) fetal well-being, (3) avoid or prevent pre-term labor, (4) fetal and uterine monitoring, and (5) maintaining uteroplacental perfusion. [Kirby, et aI., Clinical Anesthesia Practice, 2002, p1168]
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What are your concerns for the fetus in or after nonobstetric surgery in the pregnant patient?
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Perinatal mortality is a common complication from elective surgery in the pregnant patient and your concern for the fetus includes possible teratogenic effects of anesthetic agents, intrauterine fetal asphyxia, and premature labor (rare, according to Kirby). Nitrous oxide has been associated with inhibition of D A synthesis avoid 20 if possible. Maternal diazepam administration is associated with cleft lip/palate avoid benzodiazepines if possible. There is an increased risk of spontaneous abortion if elective surgery is done during the first or second trimester (most organogenesis occurs in the first trimester). [Duke, Secrets, 2000, p319; Kirby, et a1., Clinical Anesthesia Practice, 2002, ppl167-1168; Barash, ClinicalAnesthesia, 2001, p1164]
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What are nine concerns related to anesthetizing the pregnant patient for non-obstetric surgery during the third trimester?
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(1) Requirements for local or inhaled anesthetics are decreased; (2) functional residual capacity is reduced; (3) metabolic rate is high; (4) gastric emptying is slowed; (5) aortocaval compression is high; (6) teratogenicity of anesthetic drugs is possible; (7) utero placental circulation needs to be monitored; (8) premature labor can be inadvertently in itiated; and (9) fetal heart rate needs to be monitored. [Barash Handbook, Clinical Anesthesia, 1997, pp593-594; Barash, Clinical Anesthesia, 1997, pp1061-1062, 1087]
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The pregnant patient requires an appendec· tomy emergently. How do you premedicate this patient?
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A non-particulate antacid, such as 30 ml of 0.3 M sodium citrate, is given about one-half hour before the procedure. If necessary, a barbiturate may be given for sedation, and glycopyrrolate, which does not cross the placental barrier, can be used as a vagolytic and antisialagogue. Note: Appendicitis is the most common surgical emergency procedure during pregnancy. [Yao and Artusio, PO PM, 1998, pp722,726]
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Why is Bicitra given to the pregnant patient?
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Bicitra (sodium citrate) is an acid neutralizing buffer that raises gastric pH, which is advantageous should aspiration occur. [Omoigui, Anesthesia Drug Handbook, 1995, p326]
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What is the most common indication for using inhalational anesthesia for vaginal delivery?
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The most common indication for general anesthesia for vaginal delivery is the necessity for uterine relaxation. Uterine relaxation, usually with a potent volatile agent, is necessary for intrauterine manipulations (turning tlle baby), complete breach extraction, manual removal of the placenta, and replacement of an inverted uterus. [Shn ider and Levinson, Anes. for OB., 1993, P 194; Barash, Clinical Anesthesia, 2005, pl161j
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How does N20 affect uterine tone?
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Nitrous oxide does not signiftcantly affect uterine tone. [Omoigui, Anesthesia Drugs Handbook, 1995, p384
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Is general anesthesia appropriate for elective vaginal delivery? Why or why not?
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General anesthesia is not indicated for elective vaginal delivery because of the inherent risk of aspiration. [Morgan and Mikhail, Clinical Anesthesiology, 1996, p711 ]
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What are the primary concerns when a general anesthetic is used on the obstetric patient?
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Decreased FRC and mucosal congestion may cause problems in the patient awakening from anesthesia. Laryngeal spasm or edema after extubation, rapid desaturation, opioid depression of respiration, and chance of vomiting or regurgitation with aspiration are potential problems. [Barash, Clinical Anesthesia, 1997, pp1068- 1070]
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What drugs are appropriate for general anesthesia for an emergency vaginal delivery?
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(I) Thiopental (4 mg/kg) and succinylcholine (1.5 mg/kg) are most used for induction. If the patient is hypotensive, use ketamine (1mg/kg) in place of thiopental. (2) After intubation, 1- 2 MAC of any potent volatile inhalation agent may be administered with 100% O2. (3) If skeletal muscle relaxation is necessary, atracurium, cisatracurium, vecu ronium, rocuronium, and/or succinylcholine infusion may be used .(4) Once the fetus and placenta are delivered, the concentration of a volatile agent is decreased to less than 0.5 MAC or discontinued; an oxytocin infusion is started (20-40 units/L of IV fluid) and a nitrous oxide opioid technique can be used. [Morgan and Mikhail, Clinical Anesthesiology, 1996, p711]
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What two physiologic changes lead to rapid oxygen desaturation during periods of apnea (e.g., induction with thiopental and succinylcholine) in the near-term pregnant patient?
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The combination of a decreased functional residual capacity and an increased oxygen consumption leads to rapid oxygen desaturation during periods of apnea. At term, maternal oxygen consumption has increased 20% and maternal functional residual capacity has decreased 20%. [Morgan and Mikhail, Clinical Anesthesiology, 1996, p693]
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What are five advantages of volatile anesthetic agents for the patient undergoing elective cesarean section?
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Low dose halothane (0.5%), isoflurane (0.75%), or enflurane (1.0%) supplemented with nitrous oxide (I) decreases awareness and recall, (2) permits higher inspired O2, (3) may improve uterine blood flow, (4) does not increase uterine bleeding, and (5) does not depress the newborn. [Shnider and Levinson, Anes. for OB., 1993, p234J
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Describe the best induction intubation technique for a C-section with a full stomach.
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After pre-oxygenation, induce with thiopental (3-5 mg/kg) and succinylcholine (1-1.5 mg/kg). Within 90 seconds, intubation is possible, having applied cricoid pressure. [Stoelting and Miller, Basics, 1994, p376 J
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List three actions that can be taken to prevent hypotension during a C-section.
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(1) Increase the effective intravascular volume by fluid loading with 500- 1000 mL 15-30 minutes prior. (2) Left uterine displacement. (3) Possibly use vasopressors, preferably ephedrine, a mixed agonist which increases blood pressure while restoring uterine blood flow. [Davison, Eckhardt, and Perese, Mass General, 1993, pp258, 259, 262J
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What is the most common cause of maternal death during obstetric general anesthesia?
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Hemorrhage is the most common cause of maternal death. [Stoelting andMiller, Basics, 1994, p3721
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Which is more important to neonatal outcome: the induction of anesthesia-to delivery interval or the uterine incision-to delivery interval?
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The uterine incision-to-delivery interval seems to be more important to neonatal outcome than the induction of anesthesia-to-delivery interval. The uterine incision-to-delivery interval is ideally less than 3 minutes (J 80 seconds). [H ughes Shnider and Levinsons Anes. for OB., 2002, pp223-225, 651-652; Norris, Ob. Anes., 1999, pp392, 405; Barash, Clinical Anesthesia, 200 I, P 1150 J
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What are the primary concerns when a regional anesthetic is used to anesthetize an obstetric patient?
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Regional anesthetic complications include hypotension, total spinal anesthesia, convulsions induced by local anesthetics, nausea, vomiting, breathing difficulties, headache, effects of nerve injury. [Barash, Clinical Anesthesia, 1997, p1067-1068, 1080]
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The pregnant patient has been given a subarachnoid block with opioids only and no local anesthetics. What conditions may have necessitated this technique?
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Subarachnoid block with opioids only would be most useful (appropriate) in high risk patients who may not tolerate the JunctionaL sympathectomy associated with spinal or epidural anesthesia. Patients who have signifIcant cardiovascular disease, such as hypovolemia, aortic stenosis, tetralogy of rallot, Eisenmenger's syndrome, or pulmonary hypertension, are candidates for this technique. [Morgan and Mikhail, Clinical Anesthesiology, 1996, p707; orris, Obstetrical Anesthesia, 1999, p444]
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Which types of block can be used for the first stage of labor?
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Paracervical, lumbar epidural, caudal, and spinal (modified saddle) blocks all can block TlO-Ll. [Stoelting and Miller, Basics, 1997, ppI067-1069]
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At what stage of/abor is a pudendal block given?
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A pudendal nerve block is given just before delivery (end of second stage). [Bonica, p487]
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Which regional techniques would block the pelvic plexus?
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Pudendal nerve block, lumbar epidural or caudal block, low subarachnoid block. [Shnider and Levinson, Anes. for OB., 1993, ppI50-151]
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What are two disadvantages of paracervical block during labor and delivery?
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(I) Paracervical block is not effective during the second stage oflabor. (2) The major disadvantage of a paracervical block is the 8- 40% incidence of fetal bradycardia that develops 2-10 minutes after injection. Fetal acidosis often accompanies the bradycardia. [Stoelting and Miller, Basics, 1994, pp364,365]
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The efficacy of epidural opioids is impaired when used in conjunction with which local anesthetic?
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Chloroprocaine is not a suitable agent for use with epidural opioids, because studies suggest that chloroprocaine interferes with the effectiveness (efficacy) of the opioid agonists. Opioid agonists with mu-receptor activity such as fentanyl and morphine have red uced effect because chloroprocaine or its metabolites compete for opioid mu receptors in the spinal cord. [Shnider and Levinson, Anes. for OB., 1993, p85; Morgan and Mikhail, Clinical Anesthesiology, 1996, p71O]
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Which opioids would be most effective when used epidurally with chloroprocaine, opioid agonists, opioid agonist-antagonists, or opioid antagonists?
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The opioid agonist-antagonists, which have their actions predominately on kappa receptors, are more effective than opioid agonists such as fentanyl or morphine which have strong mu receptor actions. Butorphanol or nalbuphine are the opioid agonist -antagonists appropriate to use with chloroprocaine; however, the opioid agonist-antagonists have a short duration of action and can cause heavy sedation. [Shnider and Levinson, Anes.for OB., 1993, p85]
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List five disadvantages of redosing the obstetric patient with epidural chloroprocaine.
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(1) Injecting a volume in excess of 20 to 25 mL has been shown to cause severe backache. (2) The efficacy of opioids is diminished by chloroprocaine, and the choice of intraspinal opioids is limited to opioid agonistantagonists such as butorphanol. (3) Chloroprocaine is metabolized rapidly if the patient's pseudocholinesterase is normal; the effects of the chloroprocaine last only 35 to 50 min. (4) Chloroprocaine may decrease the efficacy of subsequent epidural bupivacaine-induced analgesia. (5) Tachyphylaxis to chloroprocaine can develop. [Sh nider and Levinson, Anes. for OB., 1993, pp85-86; Stoelting, PPAP, 1991 , p156]
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Why would you choose to give a laboring woman an epidural?
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An epidural or spinal anesthetic will relieve pain and anxiety initially and then during the first and second phases of labor, epidural analgesia blunts the increases in maternal cardiac output, heart rate and blood pressure. This may convert a dysfunctional labor pattern to normal. This may benefit the fetus by eliminating maternal hyperventilation which leads to reduced fetal arterial oxygen tension. [Barash Handbook, Clinical Anesthesia, 1997, p1274]
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What do you want to maintain in the healthy (nontoxemic) pregnant patient undergoing lumbar epidural anesthesia: systolic pressure, diastolic pressure, or mean arterial pressure?
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Systolic pressure. You want to prevent the systolic pressure from decreasing from baseline by 20 to 30% or falling below 100 mm Hg. [Shnider and Levinson, Anes.for OB., 1993, p397; Morgan and Mikhail, Clinical Anesthesiology, 1996, p709; Miller, Anesthesia, 1994, p2047]
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The parturient has received a neuraxial opioid and is experiencing nausea and vomiting. Which drug is effective for opioidinduced nausea in laboring women, but has the most significant side-effects?
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Droperidol is effective for the treatment of nausea in laboring women, but it has significant side-effects, namely dysphoria, akathisia (an unpleasant sensation of "inner restlessness" accompanied by the inability to sit still), and oculogyric crisis. Furthermore, the FDA has issued a "black box" warning because of the concern that the administration of droperidol may result in an increased risk of cardiac arrhythmias. [Chestnut, OB Anes. 3e. 2004 pp3s8; Authors]
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The APGAR scoring system for the standard evaluation of newborn infants during the first 60 seconds after delivery assesses what five parameters?
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(1) Heart rate, (2) respiratory effort, (3) reflex irritability, (4) muscle tone, and (5) color. [Barash Handbook, Clinical Anesthesia, 1997, ps92]
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List seven actions that should be taken if the newborn's APGAR score is 4-6.
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(I) Oropharyngeal airway inserted, and (2) O2 applied under pressure of 16-20 cm H20 for 1-2 seconds. If no response, (3) visualize airway with laryngoscope, (4) insert endotracheal tube, (5) ventilate through tube gently at 25-35 em H20, (6) start spontaneous respiration, (7) withdraw endotracheal tube after the infant has taken five or six breaths. [Barash Handbook, Clinical Anesthesia, 1997, p1082]
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List five actions that should be taken if the newborn's APGAR score is 0-3.
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(1) Establish ventilation without delay; (2) inspect glottis with scope; (3) if meconium is present, suction at once before lungs are inflated; (4) severely depressed infants may require 3-8 minutes of artificial ventilation before spontaneous gasp is taken; and (5) severe acidosis (pH 15 mEq/L) should be corrected promptly with sodium bicarbonate infused over two minutes to a total dose of2 mEq/kg. [Barash Handbook, Clinical Anesthesia, 1997, pl082-lOS3]
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What APGAR scores indicate that the neonate is severely depressed? What drugs might be appropriate for resuscitating the neonate with an APGAR score of 3?
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An APGAR score of 0- 3 indicates a severely depressed neonate. Epinephrine should be given for asystole or a spontaneous heart rate less than SO (some sources suggest atropine sulfate for bradycardia). Naloxone is given to reverse respiratory depression if opioids were given to the mother in the last four hours of labor, and the mother is not addicted to opioids. Other drugs that may be indicated for specific situations include sodium bicarbonate if the fetus is acidotic (pH < 7.1), calcium chlo ride in the presence of hypocalcemia, and dextrose in the present of hypoglycemia. [Morgan and Mikhail, Clinical Anesthesiology, 1996 p274; Duke and Rosenberg, Secrets, 1996, pp386-387]
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What is the neonatal dose of epineph rine for treatment of asystole?
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Epinephrine, 0.01-D.03 mglkg (0.1-0.3 mLlkg of a I: 1 0,000 solution), should be given for neonatal asystole or neonatal spontaneous heart rate < 60 bpm. Epinephrine administration may be repeated every 3-5 minutes, and epinephrine may be given down an endotracheal tube if venous access is not available. [Morgan, Mikhail, and Murray, Clinical Anesthesiology, 3rd ed., 2002, p84s1
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What is the appropriate drug [or the neonate with an APGAR score of 3 after 5 minutes?
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Sodium bicarbonate. Sodium bicarbonate may be administered during prolonged resusci tation (>5 minutes), particularly ifblood gas measurements are not available. [Morgan and Mikhail, Clinical Anesthesiology, 1996, pp724-725]
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The pregnant patient delivered baby under general anesthesia; what factor(s) correlates most with a depressed APGAR score at one minute?
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The general anesthetic factors which most depress the APGAR score at one minute are low FIOz and high zO. Initial lower APGAR scores under general anesthesia are probably due to transient sedation rather than asphyxia. The incidence of depressed APGAR scores at one minute can be markedly reduced by techniques that include: (1) higher FIOz, (2) reduced NzO, (3) lower dose (0.5 MAC) halogenated agents, (4) continuous lateral tilt, and (5) expeditious delivery time. Note: the fears that high maternal paz may cause uterine vasoconstriction are unfounded (Norris). [Hughes Shnider and Levinsons Anes.for OB., 2002, pp223- 225, 651-652; Norris, Ob. Anes., 1999, pp392, 405]
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What is done for the infant who is born with thin meconium in the mouth?
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For watery thin meconium found only in the mouth. a bulb syringe is used to suction the oropharynx followed by suctioning of each naris.[Cote, ed., PA le, 2e, p214; Barash, Clinical Anesthesia, 1997, pp 1093- 1094J
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If a newborn has meconium and blood below the cords, what are the appropriate actions?
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If meconium is below the cords, intubate and suction. [Davison, Eckhardt, and Perese, Mass General, 1993, pp513-514]
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What should be monitored during meconium suctioning?
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Heart rate should be monitored during suctioning. "Suctioning should not be carried out to the point of severe bradycardia or cardiac arrest." [Cote, ed. , PAlC, 2e, p2 14]
