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 |