anesthetic considerations for women having surgery while pregnant alan. c. santos, md, mph st....
TRANSCRIPT
Anesthetic Considerations for Women Having Surgery While
Pregnant
Alan. C. Santos, MD, MPH
St. Luke’s-Roosevelt Hospital Center
New York, NY 10025
Contents
• Scope of the Problem
• Maternal Considerations (brief)
• Fetal Considerations Teratogenicity Obstetric Outcome Long-Term Consequences?
• Nuts and Bolts
Scope of the Problem
• 0.3 to 2.2% of all pregnancies
• 87,000 in US and 115,000 in Europe
Am J OB/GYN 1980; 138:1167Am J OB/GYN 1989; 161:1178
Indications
• Gynecologic/Obstetric circlage torsion
• Other Abdominal Surgery appendectomy cholecystectomy
• Trauma
Maternal - Hemodynamics
• Increase in plasma volume hemodilution - lower hematocrit greater free fraction of drug dilution of cholinesterase
• Increase CO/decrease SVR/±BP
• Aorta-caval compression
• Hypercoagulable state
Maternal - Respiratory
• Increase in minute ventilation increase arterial oxygen tension decrease in arterial carbon dioxide Ph remains unchanged
• Decrease in FRC
• Increase in oxygen consumption
Maternal - Gastrointestinal
• Relaxation of gastroesophageal sphincter heartburn
• Mechanical factors (growing uterus)
• Delayed gastric emptying opioids labor
Maternal – Local Anesthetic Effect
Group CSF Progesterone ng.ml-1
Dermatomal Spread
Non-pregnant 0 T3-T11
1st Trimester 0.23 T3-T11
2nd Trimester 0.49 C8-T11
3rd Trimester 1.46 C7-T7
BJA 1995; 75:683
Fetal Risks
• Congenital Anomalies
• Spontaneous abortion/embryonic loss
• Premature labor
• Fetal demise
• Long term consequences???
Teratogenicity
• Structural (exposure day 15 – 55) Congenital anomalies Growth restriction Enzyme deficiency Resorptions/Death
• Behavioral (exposure late pregnancy) Emotions Learning Adaptive
Teratogenicity
• Species Vulnerability
• Timing of Exposure
• Magnitude of Exposure
• Susceptibility/Genetic Predisposition
METHYLTERAHYDROFOLATEHOMOCYSTEINE
METHIONINE TERAHYDROFOLATE
S-ADENOSYLMETHIONINE
ACTIVE FORMATE
FORMYLTETRAHYDROFOLATE(FOLINIC ACID)
FORMYLTETRAHYDROFOLATE(FOLINIC ACID)
MethionineSynthetaseMethionineSynthetase
METHYLENE TETRAHYDROFOLATE
DIHYDROFOLATETHYMIDINEDNA
DEOXYURIDINE
Nitrous Oxide Teratogenicity
• N2O 70% - fetal resorption/malformation
• N2O & Folinic – partial reversal
• N20 & Isoflurane – reversal
• N20 7 Pnenoxybenzamine - reversal
Preventing Nitrous Oxide Effects
• Limit exposure
• No benefit from folinic acid
• Combine with potent agent
CNS Growth and Development
• 2nd trimester to 2nd postnatal month: major period of myelination
• 2nd and 3rd trimester: neuronal proliferation and migration region specific synaptogenesis remodeling
• 80% of adult brain volume by age 2 years
Potential Anesthesia CNS Effects:
Exposure+ GABA-NMDA
Cognitive: IQ psychomotor memory, attention
Morbidity: mental retardation affective disorders degenerative dis.
Mortality: early death
CNSToxicity
Mechanisms:(+) Apoptosis
(-) Neurogenesis ∆ Cytoskeleton
∆ Dendritic spines(-)Synapse
UNDEFINED?
Courtesy: Lena Sun
Early Exposure to Anesthetics
• ANIMALS: Sprague-Dawley rat pups day 7
• METHODS: Control: DMSO Study: 6 hour exposure to mock GA N2O in oxygen midazolam in DMSO isoflurane
J Neurosci 2003; 23:876
CNS Effects
• Atlanta Birth Defects Case-Control Database
• Infants born with major CNS defects No anesthesia General Anesthesia
Am J Public Health 1994; 84:1757
Anesthesia for Cesarean Delivery and Learning Disabilities
• Deliveries in Olmsted County, 1976-1982
• Cohort review: Vaginal Delivery Cesarean Delivery – GEA Cesarean Delivery – Regional
• Assessment of Learning
Anesthesiology 2009; 111:302
Isoflurane Exposure In Utero
• Animals: Pregnant rats at day 14
• Methods: Exposure to: isoflurane in 100% oxygen 100% oxygen
• Results: impaired spatial memory reduced anxiety
Anesthesiology 2011; 114:521
Hyperoxia is also bad!
• J Neurosci 2008; 28:1236
• J Neurosci Res 2006; 84:306
• Cell Death Differ 2006; 13:1097
• Neurobiol Dis 2004; 17:273
What Are the Limitations?
• Species: Rats vs Lambs vs Humans
• Study Design: Retrospective
• Dose and Magnitude of Exposure
• Specificity: All Drugs Equal All the Time?
An Academic Exercise?
• Surgery during pregnancy is undertaken only if absolutely necessary
• Mothers will require an anesthetic is regional better than general?
• Children requiring surgery need anesthesia
Any inhalational agent better: desflurane-isoflurane-sevflurane?• Animals: Neonatal mice
• Methods: Determine MAC in littermates Study: 0.6 MAC for 6 H Control: 6 h fast in RA Euthanize – caspase-3 neurons
• Results: No differences among the 3 agents
Anesthesiology 2011; 114;578
What Are the Important Determinants of Fetal Outcome?
• Maternal Disease
• Site of Surgery Obstetric Pelvic Abdominal Peripheral
Reproductive Outcome After Anesthesia and Surgery During Pregnancy
• All women delivering in Sweden 1973-1981
• Linked Registries:
Birth registry Congenital Anomalies Hospital Discharges
AJOG 1989; 161:1178
Appendectomy During Pregnancy
• All women delivering in Sweden 1973-1981 *appendectomy
• Linked Registries:
Birth registry Congenital Anomalies Hospital Discharges
Obstet Gynecol 1991; 77:835
Appendectomy During Pregnancy
• Prior to 24 weeks – no effect
• Of women at 24 to 36 weeks delivered: day of 16% day after 5% within 1 week 22%
Laparoscopy During Pregnancy
• Subjects: Women having abd/pelvic surgery Sweden – 1973-1993
• Method: Linked registries:
Birth registry Congenital Anomalies Hospital Discharges
Am J OB/GYN 1997; 177:673
Pregnant Patient
Elective Surgery Essential Surgery Emergency Surgery
Delay until postpartum 1st trimester 2nd/3rd trimester
If no minimal increased risk to mother, consider
delaying until mid-gestation.
If greater than minimal increased risk to mother,
proceed with surgery.
Proceed with optimal anesthetic for mother, modified by considerations for maternal physiologic changes and fetal well being.
Consider consulting a perinatologist or an obstetrician.
Intraoperative and postoperative fetal and uterine monitoring may be useful.
Nuts and Bolts (1)
• Timing as discussed
• Pre-anesthesia assessment: surgical disease co-morbidities gestational age risk of aspiration physiologic alterations fetal assessment
Nuts and Bolts (2)
• Prior to fetal viability: confirmation of FHR by Doppler
• At fetal viability: hospital that can manage obstetric issues obstetrician to assume care continuous fetal monitoring????
Nuts and Bolts (3)
• Second trimester on: avoid aorta-caval compression oxygenation and ventilation maintain blood pressure
• Choice of Anesthesia based on maternal condition avoid hyperoxia regional vs general??????