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OB 7
Princinples II Non-Obstetric surgery for pregnant patient
| Question | Answer |
|---|---|
| How many pregnant women undergo nonobstetric surgery | 0.5 - 2% |
| How many anesthetic per year | 80,000 |
| Trauma complicates | 6-7% of pregnancy |
| What are some perioperative risks | Fetal loss, fetal asphyxia, premature labor, premature ROM, difficulty airway, thromboembolism teratogens |
| Non OB surgery most common surgical procedures are | Cervical incompetence Appendectomy Adnexal/Ovarian Surgery torsion Trauma Cholecystectomy Bowel Obstruction adhesions Breast surgery |
| Cervical cerclage | is the surgical intervention used to prevent fetal loss from cervical incompetence. An incompetent cervix is the result of weakness of cervical os caused by trauma, congenital or multiple pregnancies Usually done between 12 and 26 weeks gestation |
| Contraindications to cerclage | - Bleeding Risks: Active labor PROM Ruptured membranes chorioamnionitis Cervical dilation > 4 cm PTL= pre-term labor Intrauterine infection cervical laceration Fetal abnormalities Abruptio Placenta |
| Did study shows any changes in patient with cervical cerclage VS patient with no cerclage | Not that much of a difference. Recent study: 252 pts with short cervix Cerclage group: 22% lasted until >33wks No cerclage group: 26% > 33 wks |
| Less common procedure | Neurosurgical procedures Aneurysm, tumor Cardiac/Valve Surgery CPB safe, circ arr not rec Transplant Urological |
| Physiological changes of pregnancy | Obstetric or Nonobstetric Surgery – major physiologic changes must be accounted for Understand the physiology, then use anesthetics and other medications to obtain goal |
| Cardiovascular changes | Increased HR, SV, CO; 50% of which occurs by 8th week of pregnancy Physiologically prepared for blood loss (delivery) Decr SVR, BP unchanged Supine hypotension syndrome Aortocaval compression decreasing preload, > first trimester |
| REspiratory | Incr O2 demand, MV (45%), TV (50%), Decr FRC, FRC/CC ratio (atelectasis supine) CC – volume at which small airways close Capillary engorgement of mucosa – edema of upper resp tract (complicating laryngoscopy) Friable (nasopharynx espec) mucosa |
| FRC | EVR + RV |
| Other Physiology | Hem: Incr blood volume (45%), red cell volume (30%), FVII, fibrinogen (hypercoaguable) GI: Decr esoph/intestinal motility, gastric emptying (?) Renal: Incr GFR, Cr clearance; BUN/Cr ‘normals’ are lower, any rise is alarming. CNS: Decr MAC (25-40%) RA&G |
| What do you do with subanesthetic doses | careful with subanesthetic doses. |
| Progesterone | Many relevant physiologic changes due to progesterone GI -Reduced pressure at LES -Increase in gastric acidity -Decreased GB motility (3% gallstones) |
| Progesterone also | Decreases SVR Sensitizes resp center to CO2 (contributes to resp alkalosis) May be responsible for decreased MAC |
| Uterine blood flow | Increases to 500- 700ml/min at term- -50 ml/min nonpregnant woman |
| UBF lacks | autoregulation. it dependent on maternal BP/CO for perfusion |
| What does maternal hypotension do to UBF | Uterine blood flow can/will decrease during maternal hypotn, sympathetic blockade, aortocaval compression, uterine hypercontractility |
| What organ in the body are autoregulated | Brain, kidney and the heart. |
| Anesthetic agents and the uterus (IV anesthetics) | Small reduction in uterine blood flow Dose-dependent BP decrease |
| Volatile anesthetics | Can decrease BP -> lower UBF Mild under 1 MAC Uterine relxation |
| Local Anesthetics | -High maternal blood levels cause uterine arterial vasoconstiction -Paracervical block - proximity to uterine AA |
| Anesthetic Agents: Fetal effects: (Dose the drug cross the placenta) | Placental transfer: MW, protein binding, lipid solubility, maternal drug conc, maternal/fetal pH MW – large drugs (>1000Da) do not cross placenta – heparin, protamine, insulin Charge – nonionized drugs cross more easily than ionized |
| Dose the drug cross the placenta | Protein binding – non protein bound drugs cross more easily, although protein bound drugs can cross (equilibrium with fetus) Lipophilic – higher lipophilicity is advantageous |
| Placental transfer (DO NOT cross) | Succinylcholine (ion) Non-Depol (MW) Glycopyrrolate Insulin Heparin |
| Placental trasfer (DO cross placenta) | DO cross placenta Volatile anesthetics Opiates Benzodiazepines Propofol Thiopental, etc Local Anesthetics Atropine B blockers Ephedrine |
| What happen when parturient is reversed | When parturient is reversed, the robinul will not cross, therefore, fetal bradycardia may occur |
| Ion trapping | Fetal blood is slightly more acidic than mother’s A distressed fetus becomes more acidic Weakly basic drugs (local anesthetics and opioids) can cross the placenta nonionized |
| What happen in an acidotic fetal environment in regards to ion trapping? | Then, in an acidotic fetal environment, they become ionized and can have trouble crossing back into maternal circulation This can cause buildup of drug in the fetus |
| Anesthesia and Fetus | Gestational age is key factor in management of parturients for nonobstetric surgery |
| What happen at 14 days gestation with anesthesia | Gest – 14 days: any adversity likely results in embryo death |
| Gestation <8weeks with anesthetics | <8 wks organogenesis: structural or developmental abnormalities possible |
| Gestation >13 weeks with anesthetics | >13 wks: less developmental risk Myelin, Motor neurons, nerve cell connections still to take place |
| 3rd trimenster with anesthetic | 3rd trimester: PTL (pre-term labor) is greatest risk |
| Elective surgery | Can wait >6 weeks postpartum |
| Best time for non OB surgery | 2 trimester |
| Anesthesia and Fetus: Chronic exposure to subanesthetic conc? | Survey found that it has a highter incidence of abortion and congenital an omalies -Female anesthsia personnel |
| Dentist/dental assistance (anesthesia and Fetus) | -Wives of dentists, female dental assistants -Spont Ab and cong anomalies -Different rates: inhal anes vs local anes -Most recent study: 19 people |
| Team of epidemiologist (after per, data in regards to anesthesia and fetus) | -Bias, uncontrolled variables -2 subsequent studies negative |
| Relative risk | Chronic N2O exposure -Spont Ab 1.3 -Congenital malform 1.2 Cigarette smoking 1.8 1-2 drinks a day 1.98 3 or more drinks 3.53 |
| Teratogens. are all anesthesia agents potentially teratogenic | Yes. Unethical to study teratogenicity -Drugs will not be tested in pregnancy, before/after market Teratogenicity depends on: -Dose Route of administration -Timing of exposure to fetus -Species, sensitivity to the agent |
| What are safe in this clinical circumstances | Local anesthetics, volatiles, induction agents, opioids, muscle relaxants are safe in clinical circumstances |
| Teratogenicity: Research Issues | Difficult to apply human and animal studies into practice variations in susceptibility between species human studies are not prospective difficulty in controls confounding multiple variables small numbers, not statistically significant |
| Documented teratogens | ACE INHIBITORS ALCOHOL ANDROGENS ANTITHYROID CHEMO-TX COCAINE COUMADIN DIETHYLSTIBESTEROL |
| More documented teratogens | LEAD LITHIUM MERCURY PHENYTOIN STREPTOMYCIN THALIDOMIDE TRIMETHADIONE VALPROIC ACID |
| DES | diethlstibesterol |
| Diethylstilbestrol | DES Synthetic steroid Dietary ingestion – cattle feed Used for breast, prostate Ca Given to teen girls to prevent “excess height” 1940-1970: given to pregnant women to prevent miscarriage |
| In 1971 what happen with DES | 1971: shown to cause clear cell adenocarcinoma in girls/young women exposed in utero 3rd generation being researched |
| Thalidomide | Sedative/hypnotic in 60’s, also used to treat morning sickness Was OTC in Germany in 1960 Eventually 10,000 cases of infants with phocomelia About 50% survived |
| Any anesthetics known teratogens (Bensodiazepines) | Association between BZs and cleft anomalies Prospective studies failed to show relationship |
| Anesthetic known teratogen (Cocaine) | Vasoconstriction, hypoxia, placental abruption |
| Anesthetic known teratogen with (Halogenated inhalational drugs) | Some animal data, 8-12 hrs of exposure during organogenesis |
| Anesthtics known teratogens with (NSAIDS) | – usually avoided, may constrict or close fetal ductus arteriosus in later gestation – Pulm Htn; higher risk of miscarriage 1st trimester |
| Anesthesia and Fetus (N2O) | Affects B12 synthesis increases adrenergic tone May vasoconstrict uterine vessels in animals Spont Ab and congenital anomalies in rats |
| Maternal conditions | Intra-abdominal infx/pathology Can incr risk of PTL Trauma 6-7% of pregnancies Most Common cz of maternal mortality Cardiac arrest 10% of maternal deaths ACLS, include LUD, cricoid?, higher compressions Delivery with 5 min of arrest |
| Trauma | Of 6-7%, most trauma occurs in 3rd trimester MVA, falls, assaults Leading cause of maternal death Direct fetal death is rare Maternal shock Placental abruption |
| Cardiac disease in the parturient | 1-4% of pregnancies complicated by cardiac disease -Rheumatic mitral disease, Ao dissection 15% of OB ICU admissions, 50% of deaths |
| Cardiac surgery in the parturient | : fetal mortality 9-30% Essentially unchanged (‘84-’96 v ‘96-’09) Peripartum cardiomyopathy – up to 5mo PP Amiodarone class D |
| Cardiac surgery in the parturient | Current recommendations: -maintain pump flow >2.5L/min - MAP > 70mmHg -Hct>28% -normothermia if possible -alpha stat pH mgt |
| Radiology | Exams should not be deferred because of presence of fetus 3 concerns for fetus -Radiation-induced cancer (1:3000 for 50 mGy, age<14) -Loss of fetus (less than 1%) -Radiation induced malformation (small head size) Risk begins about 100 |
| Radiation | 50-100mGy(milligray) –begin to expect adverse events - 3 mGy per year from background radiation Pelvic xray – 0.16 mGy Pelvic CT 20-50 (5-10??) mGy Ultra Sound or DPL |
| Radiation risks | Pediatric CT scans Avg mGy exposure 50mGy Increased risk of leukemia and brain tumors 175,000 patients Every 10,000 scans would produce 1 leukemia and 1 brain tumor |
| Anesthesia management is to | Maintain uterine perfusion + Adequate maternal oxygenation = preservation of fetal oxygenation |
| Anesthesia Management generally | Preoperative assessment Maintain maternal oxygenation, cardiac output, oxygen delivery Maintain uterine perfusion Fetal Monitoring Postop monitoring Postop analgesia and ca |
| Preoperative assessment | Includes HCG for women of child bearing age Aspiration Precautions Risk stratification and counseling Elective surgery postpone 6 wks postpartum Nonelective surgery – 2nd trimester Anes technique Educate pt on signs of preterm labor |
| Aspiration Precautions | Anesthesia technique MAC/IV sedation Unprotected airway Comfort vs airway reflexes Regional With or without sedation? General RSI +/- cricoid pressure Aiway equipment available ETT |
| Intraoperative FEtal Monitoring | FHR monitoring possible at about 18 weeks Only advised if fetus is considered viable (why otherwise?); at least 22-24 wks If not viable (<24 wks), check fetal heart tones pre and post op FHR by transabdom or transvaginal |
| during intraop fetal bradycardia generally means what? | Fetal bradycardia – generally indicates fetal distress (neostigmine/glycopyrrolateBeat-to-beat variability is decreased by general anesthesia, opiates, other CNS drugs Also by fetal hypoxia, acidosis |
| Intraop fetal monitoring must be monitored by who? | By a qualified (OB RN) |
| Has monitoring FHR improve outcome? (OB-pt consult) | Monitoring intraoperative FHR has never been shown to improve fetal outcome If detects early fetal compromise, may allow for adjustment Must have capability for immediate delivery (stat C/S – obstetrician, equipment available) Not anesthesia decision, OB |
| ACOG opinion # 474 | The decision to use fetal monitoring should be individualized and, if used, should be based on gestational age, type of surgery, and facilities available. Ultimately, each case warrants a team approach (anes, OB care providers, surg,ped,and RN) |
| The ACOG made this state, that the reasons is | for the optimal safety of the woman and the fetus” |
| Intraoperative management (anesthesia) | Choice of anesthetic None proven to be superior Depends on case, pt, co-morbid conditions Pt anxiety MAC or IV sedation Unprotected airway, Decr MAC Regional Convert to GA unexpectedly Anxiety, sedation Awake patient |
| General anesthesia | -Loss of airway -Fetal exposure to more anesthetic |
| what to avoid in intraoperative management | Hypoxemia Hypercarbia – fetal acidosis Hypocarbia – decr uterine perfusion Hypertonicity of uterus – no autoreg Hypotension – if prolonged, poses major risk to fetus |
| PTL (Preterm Labor) | Most difficult problem to overcome Preterm delivery – most common cause of fetal loss Usually surgery/process is most closely related, NOT the anesthetic No reliable technique to treat or prevent PTL |
| PTL | May complicate 3.5% of nonobstetric surgeries More common intra-abdominal, near uterus Least common 2nd trimester surgeries, avoiding uterine manipulation ? Use of preventative tocolytics MgSO4, terbutaline, CCBs |
| complications of tocolytics | Pulmonary edema Arrythmias, hypokalemia |
| Post op | Analgesia Opioids regional Thromboprophylaxis Is regional planned? Hypercoagulable state Virchow’s triad Hypercoaguability, stasis, endothelial injury |
| What is Virchow's triad | Hypercoaguability, stasis, entothelial injury |
| Outcome (Manitoba Canada) | 70s, 2500 pregnant women having surgery Incr spont Ab in 1st and 2nd trimester No increase in congenital anomalies |
| Outcomes in Sweden | 70s, 2500 pregnant women having surgery Incr spont Ab in 1st and 2nd trimester No increase in congenital anomalies |
| Laparoscopic Surgery | Established safety Decreases opiate req and LOS in 1st and 2nd trimesters Changes in CI, SVR, MAP similar to nonpregnant Mechanical ventilation more difficult Limited use of trendelenburg |
| LOS | Lenght of stay |
| Lap surgery part 2 | Avoid hypercarbia – ETCO2 as monitor Fetal resp acidosis does occur Pneumoperitoneum – 15mmHg; does it decrease uterine blood flow? Overall: No signif diff in PTL or other s/e noted on laparotomy vs laparoscopy |
| SAGE | Society of gastrointestinal and endoscopic surgeons |
| Guildlines for diagnosis treatment and usof of laparoscopy for surgical problems during pregnancy | Practice/Clinical Guidelines published on: 09/2007 by the Society of American Gastrointestinal and Endoscopic Surgeons (SAGES) http://www.sages.org/publications/publication.php?id=23 |
| External Cephalic version | Attempt to avoid cesarean section due to breech presentation Data shows increased success rates when epidural/CSE analgesia is provided Success rate 58% 4% return to breech If serious complication occurs, epidural catheter can be used for emergency c/ |
| Fetal surgery | Performed in a few major centers -Congenital diaphragmatic hernia, hydronephrosis, twin-twin transfusion syndrome, hydrothorax, myelomeningocele |
| Major problem with fetal surgery is | is postoperative preterm labor Tocolytics: volatiles, terbutaline, NTG |
| Anesthesia concerns | -maternal safety, uterine relaxation, fetal immobility, premature labor, postop pulmonary edema -High dose inhalational anesthesia for anesthetizing mother and fetus and provide uterine relaxation |
| Fetal immobilization | Fetoscopy, open surgery Fetal Immobilization can be achieved: Why not NMBs? Classically diazepam Opioids, Remifentanil can be used during RA |
| EXIT | Ex Utero Intrapartum Treatment Used for oropharyngeal or neck masses Or other situations that would compromise newborn airway C-Sx under GA, fetal head is delivered, but placenta is kept intact until airway is secured |
| Practical Approach | 2nd trimester surgery if possible Aspiration prophylaxis LUD ?FHR monitoring Laparoscopy is possible Regional anesthesia if feasible, o/w GA/RSI/ETT All anesthetics can be used |
| (practical approach) All anesthetic can be used | Evidence does not support avoidance of IV or volatile anesthetics, opioids, local anesthetics Probably avoid NO2, BZ’s AVOID: hypoxemia, hypercarbia, hypocarbia Keep CO2 in normal pregnancy range Hypotension – treat aggressively |
Created by:
eonaodow
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