*With the exception of programs from the ACCEL series, each of which qualifies for up to 4 Category 1 CME credits.
NEW Audio-Digest Anesthesiology
Volume 55, Issue 13
April 7, 2013
Obstetric Emergencies for the Nonobstetric Anesthesiologist Lydia S. Grondin, MD
Analgesia During Labor Robert R. Gaiser, MD, MSEd
The following is an abstracted summary, not a verbatim transcript, of the lectures/discussions on this audio program.
Anesthesiology Program Info Accreditation InfoCultural & Linguistic Competency Resources
Anesthetic Care of the Obstetric Patient
The goals of this program are to improve the management of obstetric hemorrhagic emergencies and labor analgesia. After hearing and assimilating this program, the clinician will be better able to:
1. Identify and administer the appropriate medical method of control to a patient experiencing postpartum hemorrhage.
2. Implement techniques to optimize uterine blood flow to support preservation of pregnancy.
3. Describe the physiology of labor and the associated pain.
4. Choose the best technique for epidural placement.
5. Prevent complications of neuraxial labor analgesia.
In adherence to ACCME Standards of Commercial Support, Audio-Digest requires all faculty and members of the planning committee to disclose relevant financial relationships within the past 12 months that might create any personal conflicts of interest. Any identified conflicts were resolved to ensure that this educational activity promotes quality in health care and not a proprietary business or commercial interest. For this program, the faculty and planning committee reported nothing to disclose. In their lectures, Drs. Grondin and Gaiser present information that is related to the off-label or investigational use of a therapy, product, or device.
Obstetric Emergencies for
the Nonobstetric Anesthesiologist
Lydia S. Grondin, MD, Assistant Professor of Anesthesiology, University of Vermont College of Medicine, and Director, Obstetric Anesthesia, Fletcher Allen Health Care, Burlington
Case example: 27-yr-old gravida 5, para 2, at 27-wk gestation with bleeding and premature rupture of membranes (ROM); good airway on examination; has history of 2 cesarean deliveries and exploratory laparotomy, and of anxiety; no active bleeding, but known anterior placenta previa (magnetic resonance imaging shows acreta, but no percreta); intravenous (IV) access obtained; patient typed and cross-matched for 4 U packed red blood cells (PRBC); obstetric-gynecologic oncology surgeon consulted; patient stable for cesarean delivery, but at high risk for bleeding
Regional anesthesia (RA): not absolutely contraindicated; consider duration of surgery (possibly prolonged due to previous abdominal surgeries) and risk for bleeding; risks — procedure may outlast spinal anesthesia (SA); sympathectomy undesirable with chance of hypovolemia; may require airway management while focusing on volume status; benefits — less exposure of fetus to volatile agents and medications (long-term effects possible); support person present; however, if bleeding occurs, support person may need escort by staff member (ie, may reduce available help); combined spinal epidural (CSE) — accommodates lengthy surgery; allows improved postoperative pain control; general anesthetic (GA) — benefits include secure airway and allowing focus on hemodynamic stability; risks include fetal exposure to multiple medications and contribution of volatile agents to uterine atony
Anesthetic plan: SA to minimize fetal exposure, with conversion to GA if prolonged procedure needed; obtain preoperative central venous access; patient developed acute bleeding, with nonreassuring fetal heart rate (FHR) tracing; rapid induction of GA with IV access and monitoring established; oxytocin (Pitocin, Syntocinon) infusion administered for bleeding from unanticipated placenta percreta and massive transfusion protocol implemented with cell salvage; estimated blood loss (EBL) of ≈3 L replaced with 4 U PRBCs, 2 U fresh frozen plasma (FFP), and 266 mL from cell salvage; patient extubated and transferred to intensive care unit
Postpartum hemorrhage (PPH): ≥500 mL for vaginal delivery and >1 L for cesarian delivery; increasing incidence in United States due to increased uterine atony (most commonly caused by prolonged induction)
Medical methods of control: oxytocin — may be ineffective after oxytocin induction; dose ≤40 U/L; may cause hypotension; methylergonovine (Methergine) — ergot alkaloid; dose 0.4 mg intramuscularly; causes systemic hypertension; carboprost (Hemabate) — prostaglandin F2α analogue; causes systemic and pulmonary vasoconstriction and bronchoconstriction; use with caution in patients with asthma; misoprostol (Cytotec) — historically administered rectally, but recent practice utilizes buccal or sublingual routes; has gastrointestinal side effects
Surgical methods of control: manual evacuation — stop uterotonic drugs, transfer to operating room, and provide RA or GA (based on hemodynamic status); resume uterotonic drugs after evacuation; uterine compression devices — intrauterine tamponade (with, eg, Bakri balloon, Sengstaken-Blakemore tube); embolization — for stable patient after vaginal delivery; surgeon should remain immediately available; temporary occlusion (2-6 wk) preserves fertility; laparotomy with or without hysterectomy — perform when derangement of vital signs exceeds that expected with EBL (suggesting uterine rupture or internal hemorrhage), or if conservative management unsuccessful; uterine sandwich — compression sutures plus balloon tamponade (imposing internal and external compression)
Cell salvage: theoretic concerns — amniotic fluid embolus, alloimmunization, and heparin contamination; single suction preferred (gave larger volume for reinfusion); minimal risk for alloimmunization seen with 0.8 mL fetal RBC in reinfusion pack (≈9 mL in maternal system after vaginal delivery)
Maternal trauma: leading cause of maternal death in developed countries; occurs in 6% to 7% of pregnancies, with 0.3% to 0.4% admitted to hospital; two-thirds due to motor vehicle accidents and 10% to 30% from falls or physical abuse; risk for serious abdominal injury increased (serious chest or head injuries less likely); most injuries blunt trauma; morbidity and mortality rates similar to those of nonpregnant patients; placental abruption most common cause (42%) of fetal death; fetal demise increases with increasing injury severity score, maternal shock, truncal injury, and vaginal bleeding; increased maternal blood volume may mask hypovolemia; pregnancy may elevate heart rate 10 to 15 bpm and decrease systolic blood pressure by 10 to 15 mm Hg, but hypotensive, tachycardic patient should be treated for hypovolemia; normal respiratory changes include elevated O2 consumption, decreased functional reserve capacity, increased minute ventilation, and pCO2 ≈30 mm Hg; hypovolemia from uterine vasoconstriction may put fetus at risk; administer O2 on arrival to prevent fetal hypoxia and acidosis; hypocapnia and alkalosis can reduce O2 delivery to fetus; maternal analgesia reduces hyperventilation; give early thought to airway management, as massive resuscitation may exacerbate difficult airway
Initial assessment: maternal — follow Advanced Cardiac Life Support guidelines; hypovolemic shock associated with fetal mortality of 80%; fetal monitoring determines viability of pregnancy
Secondary survey: assess laboratory values; type and cross; administer immunoglobulin for Rh-negative patient; radiographic studies — should allow for viable fetus; fast examinations have sensitivity of 83% for intraperitoneal fluid in pregnant patient; computed tomography (CT) can lead to neonatal neoplastic effects (use with caution); indications for diagnostic laparotomy — same as for nonpregnant patients
Direct abdominal trauma: causes placental abruption in ≤66% of cases (consider abruption in suddenly unstable anesthetized patient); standard of care dictates continuous FHR monitoring and tocodynamometry; negative predictive value 100% for pain-free patient with normal FHR and tocodynamometer tracing
Reasons for delivery: control hemorrhage, enable exposure of nonobstetric injuries, or for unstable spinal injury; with emergent delivery, infant survival 45% and maternal survival 72%; in cases of maternal cardiac arrest, make decision to deliver within 4 min (may aid maternal resuscitation)
Intraoperative management: secure airway; risks for difficult intubation, aspiration, and hypoxia elevated; perform left uterine displacement to prevent uterine aortocaval compression; use laboratory values to guide product administration
Preservation of pregnancy: optimize uteroplacental blood flow if delivery delayed; maintain blood pressure with vasopressors (eg, ephedrine, phenylephrine); avoid maternal hypovolemia and hypoxia; severe hypercapnia can cause myocardial depression and hypotension in fetus; normothermia beneficial to coagulation status; FHR — can be monitored at ≥18 wk gestation; variability present at 24 to 27 wk; trained personnel should monitor and make decisions; have plan if FHR tracing becomes unstable (delivery vs continued monitoring); discuss case with obstetrician; obtain preoperative FHR to ascertain viability, and establish postoperative FHR and tocodynamometry
Transfusion therapy: based on trauma studies; early initiation of blood components prevents dilutional coagulopathy; hypotensive resuscitation may be attempted, but must be modified based on fetal wellbeing; transfuse using 1:1:1 ratio of PRBCs to FFP to platelets
Recombinant factor VIIa: approved by Food and Drug Administration (FDA) only for hemophilia patients; has potential for thromboembolic complications; expensive (≈$10,000 per dose); its use for maternal bleeding (often, low tissue factor states) described in many case reports; results inconclusive (based on biased studies)
Tranexamic acid: inhibits plasminogen activation and plasmin activity, which prevents clot breakdown; contraindicated in disseminated intravascular coagulation; CRASH-2 study saw reduction in all-cause mortality of 9%, with no increase in vascular occlusive events; also associated with slightly decreased blood loss in normal cesarian deliveries, decreased need for uterotonic drugs, increased hemoglobin 24 hr postoperatively, and faster cessation of PPH
Conclusions: treat stable patients like other obstetric patients, but have backup plan in place and maintain extra precautions (eg, large bore IV); treat unstable patients like trauma patients (utilize surgical and medical methods of hemorrhage control); cell salvage safe and effective; special needs of pregnant trauma patients include changes in ventilator settings, left uterine displacement, and possible fetal monitoring or delivery
Analgesia During Labor
Robert R. Gaiser, MD, MSEd, Professor and Program Director, Department of Anesthesiology and Critical Care, Hospital of the University of Pennsylvania, Philadelphia
Definition of labor: pathophysiologic process in which sufficiently frequent, strong uterine contractions cause thinning and dilation of cervix, permitting passage of fetus from uterus through birth canal; 2 components of labor (cervical dilation and uterine contraction) account for sensation; original Friedman labor curve represented period of minimal cervical dilation followed by rapid cervical dilation; currently, onset of contractions to cervical dilation considered stage 1, and complete cervical dilation to delivery of baby considered stage 2; original curve developed when most parturients <70 kg and without epidurals (1950s), and does not apply to current patients; modern curve shows more linear progression through first stage of labor; with epidural, duration of stage 1 ≈4 hr (stage 2 ≈1 hr)
First stage of labor: visceral pain, primarily result of dilation of cervix, with small component from mechanical receptors; nerves pass through paracervical region and synapse in lamina 5 of dorsal horn; cutaneous fibers from T10 to L1 also synapse in lamina 5 of dorsal horn; pain referred to T10 to L1 distribution (nonspecific sensation)
Second stage of labor: somatic pain occurs as baby descends through birth canal, causing stretching of fascia, skin, subcutaneous tissue, and other somatic structures; localized pain in perineum caused by pudendal nerve (synapses at S2-S4); anesthetic plan must address T10 to L1 (stage 1) and S2 to S4 (stage 2)
Chronic pain after delivery: chronic postsurgical pain known entity (after, eg, breast surgery, thoracotomy, inguinal hernia); cohort study reveals 10% of women complain of acute pain 36 hr postdelivery; ≈10% of women also report pain 8 wk postpartum; patients become hypersensitized during immediate postpartum period; prevention of acute postpartum pain theorized to decrease chronic pain associated with vaginal delivery
Informed consent: courts upheld maternal consent during labor; birth plan not informed consent, and active experience of labor may influence decisions
Techniques for epidural placement: ultrasonography — complicated, with prolonged learning curve; not often used; study found distance from skin to epidural space decreased in Asian population, compared with black population (accidental dural puncture more common in Asian patients)
Loss of resistance to air vs saline: 50% of providers use air and 50% use saline; no difference found in incidence of accidental dural puncture; risk for postdural puncture headache (PDPH) markedly higher in air group vs saline group: PDPH caused by air in intrathecal space (has rapid onset); technique during study used full 5 mL of air; technique safe if least amount of air possible used (ie, syringe not emptied); meta-analysis shows no difference in outcome, number of attempts, paresthesias, or accidental dural puncture; injection of saline (3-5 mL) into epidural space before introducing catheter decreases probability of cannulation of epidural vein
Input from patient: among morbidly obese patients, often helpful in identifying midline
Sleep deprivation: study reveals no difference in time to placement, number of attempts, or complications when comparing providers at beginning or end of 24-hr shifts; more providers harmed by 24-hr call than patients
Infectious complications: epidural abscess — incidence high following neuraxial anesthesia in obstetric population; collection of pus in epidural space compressing spinal cord; incidence 1 in 200,000; more common in immunocompromised patients; most common organisms Staphylococcus aureus and Staphylococcus epidermidis (skin flora); meningitis — presents with headache 8 hr to 8 days after dural puncture (similar to PDPH); aggressive approach indicated if fever present; generally occurs in healthy people; causative agent α-hemolytic streptococci (respiratory organism); mask should be worn during epidural placement and changed between patients (case of maternal death from meningitis documented in which organism cultured from respiratory track of anesthesiologist)
Preparation of skin: chlorhexidine not approved by FDA;, culture positive 1 in 3 times after iodine preparation (air dried), but only 1 in 10 times after chlorhexidine preparation; adding alcohol yields even better results; FDA approval withheld because chlorhexidine causes irreversible conduction of phrenic nerve in rats, and documentation of one case of aseptic meningitis
Labor analgesia: guidelines — goal of least amount of motor block possible (decreases risk for operative vaginal delivery); multiple infusates available; Cochrane review confirms epidural results in improved pain relief, reduced neonatal acidosis, increased incidence of assisted vaginal delivery (due to motor block), and higher incidence of hypotension, compared with no epidural
Patient-controlled epidural analgesia (PCEA): associated with fewer interventions and less local anesthetic use, compared with continuous infusion; pain with pushing slightly higher with PCEA, but no difference in satisfaction rates reported
Automated bolus: study randomized patients to 2.5 mL every 15 min, 5 mL every 30 min, or 10 mL every 60 min, with same infusate; patients receiving 10 mL bolus most comfortable; larger bolus produces increased spread in epidural space, with improved sacral anesthesia; speaker now uses low continuous rate (5-6 mL/hr), with 8 mL bolus every 20 min or 10 mL bolus every 30 min
Dr. Grondin was recorded at the 17th Annual Vermont Perspectives in Anesthesia, held March 7-11, 2012, in Stowe, VT, and sponsored by the University of Vermont College of Medicine. Dr. Gaiser was recorded at Scottsdale Anesthesia: New Developments and Controversies, held October 21-25, 2012, in Scottsdale, AZ, and sponsored by Holiday Seminars. For information on upcoming meetings sponsored by University of Vermont College of Medicine, please visit cme.uvm.edu, and for those sponsored by Holiday Seminars, visit holidayseminars.com (or check our website, Audio-Digest.org, under “Upcoming Meetings”). The Audio-Digest Foundation thanks the speakers and the sponsors for their cooperation in the production of this program.
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