(BQ) Part 2 book “A practical approach to obstetric anesthesia” has contents: Ultrasound and echocardiographic techniques in obstetric anesthesia, impact of neuraxial analgesia on obstetric outcomes, newborn resuscitation, obstetric emergencies, postcesarean analgesia, postpartum tubal ligation, endocrine disorders, management of the opioid dependent parturient,… and other contents.
Postpartum Issues Postcesarean Analgesia Richard N.Wissler I Introduction II Multimodal therapy A Goals B Components of multimodal therapy III Medications: oral, systemic, neuraxial, and regional administration A Opioids B Local anesthetics C Nonsteroidal anti-inflammatory drugs D Acetaminophen E Other medications F Medications in breast milk IV Summary KEYPOINTS The use of multimodal analgesia and differing routes of administration will increase overall postcesarean delivery (post-CD) analgesia and reduce the incidence of unwanted side effects 2 Opioids are the mainstay of post-CD analgesia Intravenous patientcontrolled analgesia (PCA) opioid administration provides superior pain relief compared to intermittent caregiver administration and may have 3 5 analgesic effectiveness comparable to neuraxial opioid administration Neuraxial opioids are the gold standard in providing post-CD analgesia by decreasing overall opioid consumption, improving ambulation, allowing earlier return of bowel function, and improving reductions in breast milk levels of opioids compared to systemically administered opioids Neuraxial opioids are associated with nausea, vomiting, urinary retention, respiratory depression, and pruritus Continuous wound infiltration with local anesthetic using catheter techniques may offer significant post-CD analgesia The use of transversus abdominis blockade does not offer significant analgesic advantage when added to neuraxial opioid administration Nonsteroidal anti-inflammatory drugs, when administered orally or intravenously and when added to local anesthetics used in neuraxial blockade, are useful analgesic adjuncts to opioids Acetaminophen may offer significant analgesia and is safe for mother and child Predicting the effects of maternally administered medications that appear in breast milk is complex Consulting the published guidelines written by professional organizations is recommended I Introduction Pain relief after cesarean delivery (CD) has many of the same clinical considerations as analgesia following other forms of abdominal surgery Additional concerns in the post-CD population include the goal of minimizing maternal sedation to facilitate interactions with the newborn, family, and friends; transfer of analgesic medications in breast milk; and reducing time to discharge to home CD is a very common surgical procedure, and anesthesiologists should be familiar with current post-CD analgesic techniques More than 1.28 million CD were performed in the United States in 2013, representing 32.7% of all births.1 As seen in the subsequent text, the anesthetic method used for CD often influences the choices for postcesarean analgesia Both scheduled and unplanned CD have similar acute postoperative pain scores and analgesic requirements.2 Acute postoperative or nociceptive pain following CD is a combination of visceral pain from the uterus and somatic pain from the abdominal wall Recent research has focused on the subsequent development of chronic neuropathic pain at the abdominal incision site Retrospective and prospective studies of chronic pain after CD report an incidence range of 1% to 18%.3 At this time, modifications of post-CD analgesia to decrease the incidence of chronic incisional pain are investigational only This chapter focuses on current analgesic strategies for acute nociceptive post-CD pain However, some data suggest that effective treatment of acute postoperative pain may minimize the development of chronic pain in these patients.4 Effective post-CD analgesia is an attainable goal recommended by several national professional organizations.5,6 One prospective written survey of pregnant patients before delivery demonstrates that pain during and after CD are the two most concerning anesthesia outcomes.7 A prospective study of healthy parturients shows that preoperative questions about anxiety, expected postoperative pain, and expected needs of postoperative analgesic medications are moderately predictive of post-CD analgesic requirements.8 However, the practical application of preoperative questionnaires for routine clinical practice is not clear II Multimodal therapy A Goals Utilizing several medications and/or routes of administration that complement each other.5,9 The goals are: Increasing the effectiveness of analgesia Decreasing medication side effects by decreasing doses of individual medications B Components of multimodal therapy Examples of multimodal therapy for post-CD analgesia include different combinations of the following: Systemic opioids Systemic nonsteroidal anti-inflammatory drugs (NSAIDs) Epidural medications a Opioids b Adjuncts c Local anesthetics Intrathecal (IT) medications a Opioids b Adjuncts Direct wound site treatments a Local anesthetics b NSAIDs CLINICAL PEARL A multimodal approach to post-CD analgesia will improve overall analgesia and reduce side effects III Medications: oral, systemic, neuraxial, and regional administration A Opioids They have historically been and remain the mainstay of post-CD and analgesic medications Reported routes of administration include intramuscular (IM), intravenous (IV), epidural, IT, oral (PO), rectal, and rarely, intranasal Systemic opioids a Specific medications studied include morphine, meperidine, hydromorphone, fentanyl, sufentanil, oxymorphone, butorphanol, and diamorphine Choice of opioid is influenced by its overall direct effects, time of onset, duration of action, and the frequency and nature of side effects b IV meperidine is seldom used for post-CD analgesia due to concerns about infant sedation by the active metabolite, normeperidine.10 However, patientcontrolled epidural analgesia (PCEA) with meperidine results in lower maternal systemic doses that should be compatible with neonatal safety during breastfeeding.11 c Diamorphine (heroin) is a Drug Enforcement Administration (DEA) Schedule I medication and not available for clinical use in the United States, although it has enjoyed widespread epidural and IT use in the United Kingdom and other parts of Europe d IV opioid administration, particularly by patientcontrolled analgesia (PCA), provides superior post-CD analgesia compared to the IM route.12 e Direct comparisons of demand-only IV PCA with IV PCA and continuous basal infusion are limited in women after CD.13 In the absence of a definite overall advantage of basal infusion IV PCA, along with safety concerns regarding respiratory depression associated with the basal infusion rates in other postsurgical populations,14 the author recommends the demand-only mode of IV PCA in post-CD patients f Table 18.1 lists the IV PCA doses for several opioids The effectiveness of IV PCA as an analgesic modality requires adequate loading doses g The demand-only IV PCA incorporates several safety features to minimize the possibility of a patient receiving unsafe doses of IV opioid First, the PCA pump is programmed to limit the amount of opioid per patient request and per hour Second, if the patient is very sedated, she will be unable to push the PCA demand button and the current opioid effect will diminish Unfortunately, even with these safeguards, adverse outcomes have occurred with IV PCA in post-CD patients Examples include visitors activating the PCA demand button for the patient (i.e., PCA by proxy) and medication and programming errors.15,16 CLINICAL PEARL IV PCA opioid administration offers superior pain relief compared to intermittent administration by health care workers Its safety is maximized if given by patient demand only without use of a low-dose baseline infusion Epidural opioids a Specific medications studied include morphine, meperidine, hydromorphone, fentanyl, sufentanil, oxymorphone, methadone, nalbuphine, butorphanol, buprenorphine, and diamorphine (not available in the United States) b The rationale for neuraxial (i.e., epidural or spinal) administration of opioids is to improve the analgesic efficacy while minimizing the side effects of the opioids when administered by other routes These side effects include sedation, respiratory depression, nausea and vomiting, itching, and urinary retention However, all these side effects can occur with either systemic or neuraxial opioids c A single dose of epidural morphine: (1) Provides better post-CD analgesia than a saline placebo17 or IM opioids12,18 (2) Has similar analgesic efficacy and patient satisfaction compared to IV PCA morphine12,18 (3) Is associated with more pruritus than IV PCA or IM morphine (4) May be less effective than if given by continuous infusion19 d Studies of PCEA in patients receiving post-CD analgesia with fentanyl, sufentanil, or hydromorphone demonstrate: (1) Better pain relief, less medication administration, and more pruritus compared to IV PCA opioids20,21 (2) No benefit of continuous basal infusion PCEA versus demand-only PCEA22,23 e A single dose of epidural fentanyl should be diluted to an injection volume of at least 10 mL for the best effect.24 However, injection volume variations with single doses of epidural morphine do not have a significant effect on post-CD analgesic efficacy.25 f Extended-release epidural morphine (1) It was approved by the U.S Food and Drug Administration (FDA) in 2004 for postoperative analgesia, with the trade name of DepoDur.26 (2) Two prospective randomized studies have compared DepoDur® to conventional morphine for post-CD epidural analgesia.27,28 The patients who received DepoDur had improved pain scores at rest and with movement as well as improved functional ability The differences between DepoDur and conventional morphine were restricted to the 24 to 48 hour postoperative time frame, but the magnitude of those differences was clinically modest (3) Although it is approved for clinical use, it is currently not being produced by the pharmaceutical company, Pacira, who currently own the license They are using the carrier, DepoFoam to manufacture the long acting local anesthetic preparation, Exparel g Table 18.2 lists the recommended single doses of conventional epidural opioids, based on prospective randomized studies h Adjuncts and epidural opioids (1) Clonidine (75 to 150 àg) improves post-CD analgesia when added to single epidural doses of fentanyl or morphine.29,30 However, there is an FDA black box warning for clonidine Duraclonđ (epidural clonidine) is not recommended for obstetric, postpartum, or perioperative pain management ” Use of clonidine alone does not offer significant analgesic improvement over neuraxial opioid use, and the associated side effects of frequent sedation and hypotension mitigate against its routine use (2) Epinephrine has demonstrated inconsistent effects in improving analgesia and reducing side effects when added to single doses of epidural opioids (3) The use of N-methyl-D-aspartate (NMDA) antagonists (e.g., ketamine, magnesium), although safe and effective in producing analgesia in a very limited number of studies, should be considered experimental at present Intrathecal Opioids a Specific medications studied include morphine, meperidine, fentanyl, sufentanil, nalbuphine, butorphanol, and buprenorphine b In contrast to systemic and epidural routes of administration, IT administration of opioids does not lead to clinically significant maternal serum concentrations of these agents.31,32 c In most circumstances, IT opioid administration implies a “single-shot” opioid delivery as part of a spinal or combined spinal-epidural (CSE) anesthetic A number of IT local anesthetics have been combined successfully with IT opioids including lidocaine, bupivacaine, tetracaine, mepivacaine, and ropivacaine d Direct comparisons of the IT and epidural routes of administration for single-dose morphine show similar efficacy for post-CD analgesia.31,32 However, the recommended dose is reduced by approximately 20-fold in the IT space e In many instances, pruritus is more prevalent and intense with IT opioids, compared with either epidural or systemic administration f Table 18.3 lists the recommended single doses of IT opioids based on the best available evidence g Adjuncts and IT opioids (1) Clonidine (60 to 150 µg) improves postcesarean analgesia when added to a single IT dose of morphine or sufentanil.33–35 IT clonidine is likely to increase the duration of the spinal anesthetic as well as maternal intraoperative sedation.34,35 Refer to section III.A.3.h.(1) for the FDA “black box” warning on neuraxial clonidine (2) Neostigmine (12.5 μg) improves post-CD analgesia and may reduce side effects when added to a subtherapeutic dose of IT morphine.36 Its short Primary apnea, 346 Primary pulmonary hypertension, 523–524 Procaine, 37t, 44t, 48 Professional negligence, 79 Progesterone, 11, 14 Prolactin, 13 Prolactinomas, 466 Prone position, 382 Prophylactic antibiotics, 245 Prophylactic epidural blood patch, 384, 407 Propofol, 504, 519, 642 Propranolol, 475 Propylthiouracil (PTU), 462t, 463 Prostacyclin analogues, 519 Prostaglandin imbalance, 439 Prostaglandins anesthetic considerations, 68 drugs, 67 mechanism of action, 67 route of administration/dose, 67–68 toxicity/side effects, 68 uses, 67 Prostaglandin synthase See Cyclooxygenase inhibitors Protein C deficiency, 485 Protein S deficiency, 485–486 Prothrombin gene mutation, 485 Pruritus, 184, 370 Pseudoephedrine, 31t Pseudotumor cerebri See Benign intracranial hypertension; Idiopathic intracranial hypertension PTU See Propylthiouracil Pulmonary artery catheter, 504 Pulmonary embolism, during pregnancy guidelines on, 697 imaging studies, 590–592, 591f introduction, 589 treatment, 592 venous thromboembolism maternal death from, 669 obesity and, 616–617 pregnancy effects on, 589 risk factors for, 590 treatment and anesthetic implications, 592–593 Pulmonary function tests, 583f, 584–585 Pulmonary hypertension, 508, 523–524 Pulmonary physiology, fetal, 344, 345f Pulmonary system, 612–614 Pulmonary ultrasound applications, 200–201 introduction, 199 sensitivity and specificity of auscultation, chest radiography, and lung ultrasonography, 201t technique, 199–200 Pulmonary vascular resistance (PVR), 507 Pulsatility index (PI), 101 Pulse oximetry, 519 PVR See Pulmonary vascular resistance Pyelonephritis, 570–571 Pyridostigmine, 550 Radiation, 85t Radioactive iodine 131, 461, 462t Rapid sequence intubation, 622–623 Recombinant factor VII, 321, 494 Reflexology, 139 Relaxation techniques, 138 Remifentanil, 148, 149–150, 150f–152f, 153, 502 maternal and neonatal effects, 155t for pheochromocytoma, 178 studies for labor analgesia, 154t Renal disease anesthetic implications altered responses to drugs, 566 potential nephrotoxins, 566 preoperative preparation and laboratory studies, 566–567 anesthetic management, 467 categories of renal dysfunction and influence on pregnancy, 561–562, 561t DM and, 456 etiology collagen vascular diseases, 564 diabetes mellitus and hypertension, 564 primary renal diseases, 563–564 renal transplant patients, 564–565 general management strategies, 565 HIV and, 124–125 introduction, 558–559 loop diuretics and, 565 monitoring, during pregnancy, 563t multidisciplinary team, 559 renal anatomy, 559 renal changes, in pregnancy, 560t renal disease, dialysis, and pregnancy outcomes, 571–572 renal failure associated with pregnancy acute fatty liver of pregnancy (AFLP), 571, 575–577, 576t acute kidney injury, 568–569, 568t, 569t hemolytic uremic syndrome (HUS), 571 preeclampsia and, 569–570 pyelonephritis, 570–571 renal colic, 571 renal function assessment, in pregnancy, 560–561 renal physiology, 559–560 signs and symptoms of acute renal decompensation, 565t systemic effects, 562, 563t of chronic renal disease, 567t Renal system, 11–12, 441–442 Resistance index (RI), 101 Respiratory diseases, obstetric anesthesia for parturients with acute respiratory distress syndrome (ARDS) and respiratory failure, 604– 605, 604t amniotic fluid embolism (AFE), 593–595 aspiration pneumonitis, 599–600 asthma, 583–589, 614 cystic fibrosis, 601–602 introduction, 582 lung transplantation, 602–603 obstructive sleep apnea (OSA), 598–599, 614f pulmonary embolism, during pregnancy, 589–593 restrictive lung disease, 603–604 sarcoidosis, 599 smoking, 597 summary, 605 venous air embolism (VAE), 595–597 Respiratory gas exchange, 24–26 Respiratory system in hypertensive disorders, 441 in multiple gestation pregnancy, 291 in pregnancy, 6–9 Respiratory tract infection, 119–120 Restrictive lung disease, 603–604 Resuscitation, 169, 530–531 See also Newborn resuscitation Retained placenta, 329–330 Retinopathy, 456 RI See Resistance index Risk disclosure, 80 Ritodrine, 56, 57 Rocuronium, 428 Ropivacaine, 37t, 41, 43, 44t, 179 for spinal anesthesia, in cesarean delivery, 253 Sacral plexus, 394 Salbutamol, 56, 57 Salvage therapies, 647 Sarcoidosis, 599 SARS See Severe acute respiratory syndrome Sciatic nerve, 395–397 Scoliosis anesthetic considerations, 536–538 cesarean delivery and, 540 clinical issues, 535–536 intrapartum management, 538–540 obstetric management, 536 other neuromuscular disorders and, 538 pathophysiology, 536–537 preanesthetic consultation, 538 respiratory function, 537–538 restrictive lung disease and, 603 Screening ultrasound survey, 97–98 S/D See Systolic-to-diastolic ratio Secondary apnea, 346 Seizure prophylaxis, 443, 444t, 448 Seizures, 408 epilepsy, 553–554, 553t Sepsis and septic shock, 129–131 neonatal shock, 356 Serum albumin concentration, 11 Serum estrogen, 11 Serum progesterone, 11 Severe acute respiratory syndrome (SARS), 128 Severe maternal morbidity, 670–671 Severe thyrotoxicosis, 459–460 Severe ventricular dysrhythmias, 45 Sheehan syndrome, 469 Shingles See Herpes zoster Shock See Sepsis and septic shock Shoulder dystocia anesthetic management, 335–336 diagnosis and recognition, 334 obstetric management, 334–335 delivery of posterior arm, 335 intravaginal pressure on posterior shoulder, 335 McRoberts maneuver, 335 suprapubic pressure, 335 Zavanelli maneuver, 335 risk factors, 334 SHS See Supine hypotension syndrome Sinus thrombosis, 381 Sleep apnea, 598, 599, 614f Smoking, 597 Society for Obstetric Anesthesia and Perinatology (SOAP), 699–700 Sodium bicarbonate, 356–357 Sodium iodide, 462t Sodium nitroprusside, 444t, 445 Spina bifida, 543–544 Spinal anesthesia anesthetic management in obstetric patients with predicted difficult airway, 274–275 for cesarean delivery, 250–253 additives to local anesthetics, 253 examples of spinal needles, 251f after failed epidural, 253 local anesthetics for, 253 potential complications, 252–253 for PPTL, 427–428 single-shot, 520, in left-to-right shunting Spinal cord injury anesthetic management, 542–543 clinical issues acute phase, 540–541 autonomic hyperreflexia, 541–542, 542t, 544 chronic phase, 541 level of injuries, 541 other complications, 541 obstetric management, 542 restrictive lung disease and, 603 with spinal needles, 400 Spinal cord ischemia, 398–399 Spinal fluid leakage, 404–408 Spinal surgery, 540 Spontaneous intracranial hypotension, 382, 408 Spontaneous vaginal delivery, 182 Sterile water injection, 142–143, 143f Stillbirth and neonatal deaths, 626–627 Streptomycin/kanamycin, 85t Stress-dose steroids, 470–471 Subarachnoid block, 390 Subarachnoid doses, 15 Subarachnoid hemorrhage, 380 Subdural hematoma, 381 Succinylcholine, 428, 475, 502, 543, 552, 642 Sufentanil, 153, 156, 179, 366, 367–368 dose ranges, 179t for PPTL, 429 recommended single doses, for postcesarean analgesia, 368t, 369t Sugammadex, 642 Sulfonamides/trimethoprim, 31t Sulindac, 61 Supine hypotension syndrome (SHS), 615–616 Supraglottic airway, 261 Suprapubic pressure, 335 Surgical cricothyroidotomy, 282 Surgical wound infiltration, 371 SVR See Systemic vascular resistance Sympathomimetics, 48 Syphilis, 127 Systemic vascular resistance (SVR), 5, 509, 520 Systolic-to-diastolic ratio (S/D), 101 T4 sensory level, 425 TA See Tricuspid atresia Tachyarrhythmias, 509t TENS See Transcutaneous electrical nerve stimulation Tension headache, 380 Teratogenicity agent effects, 30 of anesthetic agents, in nonobstetric surgery, during pregnancy, 84–85, 86t classification of birth defects, 29 dose effect, 30 drug teratogenicity, 30–31, 30t, 31t etiology of congenital malformations, 29 genetic susceptibility, 29 manifestations, 29 mechanisms of, 29 principles of, 29–30 timing of exposure, 29 Terbutaline, 56, 111 Terminal apnea, 346 Tetracaine, 37t Tetracycline, 31t, 85t Tetralogy of Fallot (ToF), 510–512 TGV See Transposition of great vessels Thalidomide, 85t The Joint Commission 2015 National Patient Safety Goals, 169 Thoracic neuraxial anesthesia, 587–588, 588f Thrombocytopenia, 492–493 Thrombolysis, 592 Thrombophilia acquired, 488 anesthetic implications, 488–489 guidelines for timing neuraxial anesthesia, in anticoagulated patient, 488, 489t guidelines on, 696–697 inherited, 485–486, 487t management of parturients with suspected thrombophilia, 486–488 recommended anticoagulation regimes, 487t recommended thromboprophylaxis, with inherited thrombophilia, 487t screening, 486 treatment, 486–488 risk factors, 484–485, 486t risk of venous thromboembolism, 486t Virchow’s triad, 484 Thromboprophylaxis, 487t, 625–626 Thrombotic control, 481f, 482–483 Thyroid disorders changes in thyroid function test results, 459t hyperthyroidism, 459–464 hypothyroidism, 464–466 introduction, 458 thyroid physiology, 458–459 Thyroid function, 12 Thyroid storm, 461–463 Thyromental distance, 268 Tinzaparin, 487t TNS See Transient neurologic symptoms Tocolytic medications See also specific medications calcium channel blockers, 58–59 cyclooxygenase (prostaglandin synthase) inhibitors, 61–62 magnesium sulfate, 59–61 β-mimetic therapy, 56–58 in multiple gestation pregnancy, 293–294 nitroglycerin, 62–63 oxytocin antagonist (atosiban), 63 ToF See Tetralogy of Fallot Tracheal intubation, 261, 277–279, 447, 448f pheochromocytoma, 474–475 Tramadol, 156–157 Transcutaneous electrical nerve stimulation (TENS), 142 Transfusion activated recombinant factor VII, 321 autologous, 317 dilutional coagulopathy, 319–320 disseminated intravascular coagulation, 320, 321t electrolyte balance, 319 massive blood loss and, 318–321, 318t monitoring, 319 in obstetric hemorrhage, 316–317, 318–319, 318t risks, 318t Transient neurologic symptoms (TNS), 48–49 Transposition of great vessels (TGV), 512–514, 513f Transtracheal jet ventilation, 283 Transversus abdominis plane blocks, 371, 663 Trauma, 88 anesthetic considerations, 642 airway management, 642 anesthetic induction and maintenance, 642 assessing severity of maternal injury, limitations, 637–638 advanced trauma life support training and use of vital signs, 637 clinical assessment of patient severity, 637–638 implications of physiologic changes of pregnancy, 637 severity of injury, 637 clinical test findings versus pregnancy outcome, 640–642 flow cytometry, 641–642 Kleihauer-Betke testing, 641 minor injuries, 641 prenatal maternal injury, 640–641 direct nerve, 399–400 epidemiology, 632–633 by fetal head, 394 general treatment guidelines, 634–637 always prefer mother, 634 assessment and implications of fetal viability, 636–637 perform trauma surveys, 634–636, 635f pregnancy workup, 636 standard care protocols, 634 introduction, 632 preterm birth and, 644 radiologic assessment, principles of, 638–640 magnetic resonance imaging (MRI), 640 standard radiology and computed tomography scanning, 639–640 ultrasound imaging, 638–639 salvage therapies, 647 specific mechanisms of injury, 643–647 burns, 646 domestic violence, 645 falls, 644 motor vehicle accidents, 643–644 penetrating injury, 646–647 summary, 647–648 uterine rupture, 644 Tricuspid atresia (TA), 514–517 Tricyclic antidepressants, 473 Trimethadione, 85t Trimethaphan, 475 Tuberculosis, 127–128 Tubulointerstitial diseases, 563–564 Ultrasound fetal, 369 screening ultrasound survey, 97–98 for trauma, 638–639 Ultrasound and echocardiographic techniques airway examination, 216 focused cardiac ultrasound, 192–198 gastric volume measurement, 211–213 intracranial pressure measurement, 209–211 introduction to, 191–192 lower extremity vein ultrasound, 216–218 pelvic/abdominal ultrasound, 213–215 pulmonary ultrasound, 199–201 scanning and equipment requirements, 192t ultrasound-guided neuraxial anesthesia, 202–208 applications, 206–208 introduction, 202 operator outcomes ultrasound-versus non-ultrasound-guided epidural analgesia, 207t technique, 202–206 ultrasound-guided regional anesthesia, 208–209 application, 208–209 introduction, 208 technique, 208 Ulysses directive, 78 Umbilical blood flow, 24 Umbilical cord blood gas measurements, 349 Umbilical cord compression/prolapse, 336 in breech presentation, 299 Umbilical cord gases, 311 Uncontrolled maternal pain, 8 Unfractionated heparin, 590, 592–593 Unintended dural puncture, 185 Urinary retention, 186 Urinary tract infection (UTI), 120–121 Uterine arteries, 20 Uterine atony, 246 epidemiology, 327–328 invasive therapy, 329 medical management, 328 Uterine blood flow, 22–24, 23f, 26f Uterine hypertonus, 56 Uterine inversion, 332–333 Uterine rupture, 644 anesthetic considerations, 327 conditions associated with, 326 definition, 326 diagnosis, 326–327 epidemiology, 326 obstetric management, 327 Uteroplacental anatomy anatomic and physiologic changes,20–21 fetal circulation, 21–22 human placenta, 21 nutrient drug/transfer, 27–29 drugs, easily crossing placenta, 28t drug transfer, 27–28 mechanisms of exchange, 27 nutrient transfer, 28–29 respiratory gas exchange, 24–26 carbon dioxide transfer, 26 oxygen transfer, 24–26 teratogenicity, 29–31 uteroplacental circulation, 22–24 placental circulatory development, 22 umbilical blood flow, 24 uterine blood flow, 22–24, 23f, 26f Uterotonic medications See also specific medications carbetocin, 65–66 ergot alkaloids, 66–67 mechanism of action, 65f oxytocin, 64–65 prostaglandins, 67–68 Uterus, 55 UTI See Urinary tract infection VAE See Venous air embolism Vaginal delivery analgesia for, 182–183 anesthesia, in multiple gestation pregnancy, 294–295 for breech presentation, 297–300, 299t hypertensive disorders and, 446–447 instrumental vaginal delivery, 182–183, 227–229 obesity and, 618–620 spontaneous vaginal delivery, 182 Valproic acid, 85t Valvular heart disease aortic insufficiency (AI), 506–507 anesthetic management, 507 cesarean delivery and, 507 general anesthesia, 507 pathophysiology, 506 peripartum considerations, 506 aortic stenosis (AS), 502–504 anesthetic management, 503–504 general anesthesia, 504 invasive monitors, 504 overview, 502–503 pathophysiology, 503 peripartum considerations, 503 mitral regurgitation (MR), 504–506 pathophysiology, 504–505 peripartum considerations, 506 mitral stenosis (MS), 500–502 anesthetic management, 501–502 general anesthesia, 502 invasive monitoring, 502 pathophysiology, 500–501 peripartum considerations, 501 mitral valve prolapse (MVP), 506 Vancomycin, 475 Varicella zoster immune globulin (VZIG), 128 Varicella zoster virus (VZV), 128 Vasa previa, 323–324 Vasopressin, 48 Vasopressor administration, 245–246 Vecuronium, 428 Vena cava filter, 592 Venous air embolism (VAE), 595–597 Venous thromboembolism See Pulmonary embolism, during pregnancy Ventilation/perfusion scans, 590 Ventilation/perfusion single photon emission computed tomography, 590–591 Viral hepatitis, 578 Vitamin A derivatives, 85t Volume expanders, 356 von Willebrand disease, 490, 491t VZIG See Varicella zoster immune globulin VZV See Varicella zoster virus Warfarin, 31t, 490t, 592 Written consent, 78 Zavanelli maneuver, 300, 335 ... Low-dose intravenous ketamine improves postoperative analgesia after caesarean delivery with spinal bupivacaine in African parturients Int J Obstet Anesth 20 12; 21 :21 7? ?22 1 68 Reza FM, Zahra F, Esmaeel F, et al Preemptive analgesic effect of ketamine in patients undergoing... These headaches are of mildto-moderate intensity and are usually bilateral, nonpulsating, and unaffected by activity Nausea and photophobia are absent Pregnancy appears to increase the incidence of tension headache C Intracranial hemorrhage... Case report: epidural blood patch in the treatment of abducens palsy after a dural puncture Can J Anaesth 20 07;54:146–150 3 Zeidan A, Farhat O, Maaliki H, et al Does postdural puncture headache left untreated lead to subdural hematoma? Case report and a review of the literature