obstetric emergencies
- 2. 5/8/2013 2 OB Emergencies Non Hemorrhagic Emergencies • Fetal distress • Impending fetal distress (2nd twin is breech, etc) Hemorrhagic Emergencies • Placental abruption • Placenta previa • Placenta acreta (increta, percreta) • Retained placenta • Uterine rupture • Uterine atony Indications for Immediate Cesarean Delivery • Persistent FHR < 80 beats/min • Frequent repeated late decelerations with poor FHR variability • Maternal hemorrhage • Impending vaginal delivery when vaginal delivery is contraindicated – Placenta previa – Frank breech presentation – Active herpes
- 3. 5/8/2013 3 Anesthesia for Emergency Cesarean Section Choice usually based on • Urgency of situation – Speed of onset: GA > existing epidural > spinal > new epidural • Maternal intravascular volume status – Hypovolemia is usually considered greater problem for regional anesthesia • Coagulation status – Coagulopathy and thrombocytopenia can be contraindications to neuraxial block placement. Epidural for Emergency Cesarean Section • Extension of an existing epidural that is working well • Dosing can begin before transport to the delivery room – increases chances of achieving sufficient block in time – risks hypotension or other regional anesthesia complications in transit. • In very urgent cases prepare for general anesthesia and assess quality of block when surgery about to begin
- 4. 5/8/2013 4 Local Anesthetics for Epidural Anesthesia • 2% lidocaine with or without epinephrine – Without epinephrine: higher pH, faster onset – With epinephrine: longer duration, easier to detect intravascular injection • 3% 2‐chloroprocaine – Fast onset but short duration often <1 hr – May interfere with effectiveness of epidural morphine • 0.5% bupivacaine – Slower onset, longer duration. • Typical dose usually 20 cc (15‐30 cc range) • Lower concentrations likely to give inadequate blocks. Anesthesia for Emergency Cesarean Section • Spinal anesthesia has rapid onset and in the right circumstances (cooperative patient with helpful anatomy, skillful provider, adequate preparation) placement can be rapid. • The use of general anesthesia for cesarean section is now largely limited to patients who have a contraindication to regional anesthesia or to the most extremely urgent operations
- 5. 5/8/2013 5 General Anesthesia for CS • Advantages: – Fast – Few contraindications – Indefinite duration – Patient not awake • Disadvantages – Airway risks – Aspiration risks – Patient not awake – Fetal uptake of anesthetics – Uterine relaxation from volatile agents – Drug interactions (e.g. neuromuscular blockers & MgSO4) Risks of General vs Regional Anesthesia • General anesthesia is generally associated with more bad anesthesia outcomes – increased risk factors in obstetric patients – increased use of GA in high risk OB patients and emergent situations
- 6. 5/8/2013 6 Hawkins JL, Koonin LM, Palmer SK, Gibbs CP. Anesthesia‐related Deaths during Obstetric Delivery in the United States, 1979‐1990. Anesthesiology 1997;86:277‐284. 1st national study in USA, performed by the CDC and National Pregnancy Mortality Surveillance System Reviewed, where available: Death certificates (1979‐1990) for all pregnancy related deaths. Pregnancy outcome data for relation to anesthesia. (89% avail.) Number of live births from National Files of Health Statistics. Estimates of C/S rates, RA and GA rates from other surveys. 4097 deaths; 129 associated with anesthesia OB Anesthesia Deaths in US NumberofDeaths(N=129) Hawkins et al., 1997
- 7. 5/8/2013 7 CI = confidence interval *Per million general anesthetics for cesarean section †Per million regional anesthetics for cesarean section 95% CI 1.8 ‐ 2.0 95% CI 1.8 ‐ 9.4 ReferentReferent1.9†8.6†919Regional 95% CI 12.9 ‐ 21.8 95% CI 1.9 ‐ 2.9 95% CI 25.9 ‐ 49.9 95% CI 17.7 ‐ 22.7 16.72.332.3*20.0*3233General 1985‐19901979‐19841985‐19901979‐19841985‐ 1990 1979‐ 1984 Risk RatioCase Fatality RateNumber of Deaths Numbers, Case Fatality Rates, and Risk Ratios of Anesthesia‐related Deaths during Cesarean Section Delivery by Type of Anesthesia: United States, 1979‐1984 and 1985‐1990 Hawkins et al., 1997 Anesthesia for Cesarean 0 10 20 30 40 50 60 70 80 90 % General Epidural Spinal CSE 1981 1992 2001 Elective Bucklin et al., 2005, Anesthesiology 103:64 2001 Emergent S 100‐500 M 500‐1499 L >1500 S M L GA 41% RA 55% GA 16% RA 84%
- 8. 5/8/2013 8 Limitations Limitations of the Hawkins study: • Numbers are estimates • Types of anesthesia from independent surveys • Data on who provided anesthesia is lacking • Details on the actual events often sparse Nonetheless: Maternal Anesthetic Mortality in UK 0 10 20 30 40 50 60 1961 1964 1967 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 Triennium Beginning GA RA Lyons and Akerman 2005, Minerva Anestesiol 71:27
- 9. 5/8/2013 9 Anesthesia for Fetal Stress / Distress Regional anesthesia safe in chronic fetal stress. General anesthesia usually preferred in dire distress ‐ placental abruption, severe fetal bradycardia, uterine rupture. Intermediate degrees of distress often managed well with regional anesthesia. Consider early use of epidural anesthesia in patients at high risk of operative delivery Peripartum Hemorrhage • Hemorrhage has been one of the leading causes of maternal mortality since records have been kept • #1 cause of maternal death worldwide • A major cause of maternal death in developed and developing countries • ~ 125,000 deaths per year • Affects 5‐15% of women giving birth • Increases morbidity in ~20,000,000 women
- 10. 5/8/2013 10 Placental Abruption • Aka abruptio placentae, accidental hemorrhage (UK) • “Premature separation of the normally implanted placenta”. Different from placenta previa in that placenta is implanted some distance beyond the cervical internal os. • Frequency ≈ 1 in 100‐200 deliveries • 10 – 12% of all third‐trimester stillbirths • Requires “emergent” CS if fetus viable and vaginal delivery not imminent • May require maternal transfusion & resuscitation Placenta Previa Placenta implanted over or very near internal cervical os. Risk of major antepartum bleed Cervical os – edge of placenta: <10 mm 10‐20 mm Risk of bleeding: 29% 3% Will require cesarean: 75% 31% Therapy: Elective delivery at 36 weeks. Risk from fetal lung immaturity < risk from hemorrhage.
- 11. 5/8/2013 11 Placenta Previa, Prior Cesarean Section and Placenta Accreta # Patients with # Patients with # Prior C/S placenta previa placenta accreta % 0 238 12 5 1 25 6 24 2 15 7 47 3 5 2 40 4 3 2 67 Clark, et al. 1985, Obstet Gynecol 66:89 Placenta Accreta Normal decidua Accreta 78% Increta 17% Percreta 5% Abnormally adherent placenta
- 12. 5/8/2013 12 Placenta Accreta Incidence: ~ 1/500 ~35 % not confirmed at the time of surgery or pathology Risk Factors: • Previous cesarean (1 CS: 0.3%, 2 CS: 0.6%, 3 CS: 2.4%) • Low lying placenta/placenta previa • Maternal age > 35 years • High parity‐gravidity • History of uterine curettage • High 2nd‐trimester AFP and β‐hCG • Previous uterine surgery • Uterine fibroids • IVF pregnancy Placenta Accreta Maternal Complications: • Postpartum hemorrhage • Maternal mortality (0 ‐ 4.25% in Western nations) • Increased rate of required uterine curettage Treatment: • Cesarean hysterectomy at 34 – 37 weeks – Decreased blood loss and morbidity if planned – Preoperative balloon catheters into the internal iliac arteries may decrease blood loss and shorten surgery – Conservative treatment should only be attempted in high risk centers prepared for sudden severe hemorrhage
- 13. 5/8/2013 13 Uterine rupture Rare when no history of uterine surgery or trauma Associated with • Direct or blunt trauma • Excessive fundal pressure, version • Forceps, curettage or other intrauterine injury • Inappropriate oxytocin • Uterine anomaly • Placenta percreta • Tumors • Fetal macrosomia, malposition, anomaly Retained Placenta • ~ 1% of deliveries • Bleeding usually slow but persistent • Usually requires manual extraction of remaining placenta • Anesthesia often needed for extraction – Good reason to delay removal of labor epidural for 30‐60 minutes after delivery • Uterine relaxation sometimes needed – Inhalation anesthesia gives excellent relaxation – Nitroglycerine 50‐150 μg iv gives good relaxation
- 14. 5/8/2013 14 Uterine atony Drugs to treat hemorrhage from uterine atony • Oxytocin (Pitocin) – Pituitary hormone – 10 – 40 units/liter continuous infusion – Direct bolus injection (> 5 units) associated with maternal hypotension and possible death • Methylergonovine (Methergine) – Ergot alkaloid; smooth muscle constrictor active also on vascular smooth muscle. Can cause vasospasm, severe hypertension if overdose or given i.v. Avoid in hypertension. – 0.2 mg IM repeat up to every 2 hrs Uterine atony • 15‐methyl PGF2α (Carboprost, Hemabate) – Prostaglandin F2α analog, smooth muscle constrictor active also on bronchial smooth muscle. Can cause/exacerbate bronchospasm. Avoid in asthma. – 0.25 mg IM. May repeat every 15 – 90 minutes up to 8 doses. • Dinoprostone (Cervidil, Prepidil, Prostin E2) – Prostaglandin E2. Can cause/exacerbate hypotension. Fever common. – 20 mg vaginal or rectal suppository, may repeat every 2 hours. – Stored frozen, must be thawed.
- 15. 5/8/2013 15 Uterine atony • Misoprostol (Cytotec) – Prostaglandin E1 analog – 800‐1000 mcg rectally or sublingually, single dose – The only prostaglandin for uterine atony that can be stored at room temperature – Caution giving sublingually in patients under GA (aspiration risk) Uterine atony: Surgical options • Uterine tamponade – Gauze packing ± soaked in saline/thrombin 5000 units/5 ml – Foley catheter; one or more, inflated – Sengstaken‐Blakemore tube – SOS Bakri tamponade tube • Uterine curretage • Uterine artery ligation • B Lynch suture (uterine corpus compression) • Hysterectomy
- 16. 5/8/2013 16 Uterine Tamponade Devices Sengstaken‐Blakemore tube SOS Bakri tamponade tube Massive Transfusion Protocol • Once initiated, Anesthesia, OB, Nursing, Blood Bank, Pathology, etc. all working from a written protocol. • Protocol readily available (i.e. by computer). • Pre‐set amounts of blood products are prepared automatically • Blood products prepared automatically, laboratory prepared to process samples quickly, ancillary personnel made available.