1. Anaesthesia for Non Obstetric Surgery in Pregnant Patients
Presenter: Dr. Satya Pal
Moderator: Dr. Geetanjali
University College of Medical Sciences & GTB Hospital, Delhi

2. Incidence 0.3% to 2.2% of pregnant women undergo surgeries
Annual incidence - 75,000 – 80,000 (USA)
Centralized data unavailable in India
Commonest surgery - Appendicectomy

3. Incidence Am J Obstet Gynecol 1989
Trimester breakdown of nonobstetric surgery undertaken during pregnancy. A
Am J Obstet Gynecol 1989

4. Surgeries in pregnancy
Pregnancy related
Cervical encirclage
Fetal surgery
Ovarian Cystectomy
Not related to pregnancy
Appendicectomy, Cholecystectomy
Trauma
Malignancies

5. How these patient are different from other surgical patients?
Two patients - mother
- fetus
Physiological changes in mother

6. Why this topic is important?
Must ensure safe anaesthesia for both mother and child
Standard anaesthetic procedure may have to be modified to accomodate both maternal physiological changes and presence of fetus
Risk to the fetus is more-
the effect of disease process,
teratogenicity of anaesthetic agents,
intraoperative impairment of uteroplacental circulation, and
risk of abortion or preterm delivery

7. KEY AREAS Normal alterations in maternal physiology during pregnancy
The potential fetal effects from anaesthesia and surgery
Maintenance of uteroplacental perfusion and fetal oxygenation
Practical considerations
Importance of maternal counselling and reassurance
Special situations
OPTIMAL ANAESTHETIC MANAGEMENT OF THESE PREGNANT PATIENTS AND THEIR FETUSES REQUIRES AN UNDERSTANDING OF THESE KEY AREAS

8. Altered maternal physiology Respiratory system:
↑ O2 consumption & ↓ FRC rapid desaturation or hypoxemia
↑ Alveolar ventilation  chronic respiratory alkalosis & ↓ bicarbonate and base buffer
↑ mucosal vascularity & weight gain difficult mask ventilation or intubation
Cardiovascular system:
Supine hypotension syndrome ↓ uteroplacental perfusion
Distention of epidural venous plexus ↑ likelihood of intravascular injection and enhanced spread of LA

9. Altered maternal physiology Hematological changes
↑ Blood volume with lesser increase in RBCs volume dilutional anemia
↑ Factor I, VII, VIII, X, XII & FDP  Increased risk of thromboembolic complications
Benign leukocytosis difficult to differentiate from infection
Gastrointestinal system changes
↓ LES tone, distortion of gastropyloric anatomy & ↑ gastric pressure from gravid uterus risk of regurgitation and aspiration

10. Altered maternal physiology…
Altered response to anaesthesia
Alveolar hyperventilation, reduction of FRC and reduction of MAC rapid induction of general anaesthesia
↓ thiopental requirements
↓ protein binding due to low albumin  ↑ free fraction of drugs
↑ sensitivity to peripheral neural blockade ↓ L.A. dose requirement

11. KEY AREAS Normal alterations in maternal physiology during pregnancy
The potential fetal effects from anaesthesia and surgery
Maintenance of uteroplacental perfusion and fetal oxygenation
Practical considerations
Importance of maternal counselling and reassurance
Special situations
The fetal effects of AA has already been discusses in detalis in previous seminar, we will be discussing the teratogenic effects of AA

12. FETAL EFFECTS Teratogenicity
Any significant postnatal change in function or form in an offspring after prenatal treatment
Factors that influence teratogenicity of a drug
Species susceptibility
Threshold or amount of exposure
Duration and timing of administration
Genetic predisposition
Manifestation of teratogenicity (Death, Structural abnormality, Growth restriction, functional deficiency)

13. FETAL EFFECTS… Teratogenicity…
Maximum sensitivity of organs for development of structural abnormalities
Brain days
Heart days
Eyes days
Limbs days
Gonads days
Organogenesis: complete at 13 weeks
day 31 to day 71after 1st day of last menstrual period

14. FETAL EFFECTS… Documented teratogens:
Radiation
increased risk of malignant disease, genetic disease, cong. malformation &/or fetal death
Maternal metabolic imbalance
Alcoholism, cretinism, diabetes, folic acid deficiency, hyperthermia, prolonged hypoxia, hypercarbia and severe hypoglycemia
Infection
CMV, Herpes virus, Parvo virus B-19, rubella virus, toxoplasmosis
Drugs

15. FETAL EFFECTS… Radiology: a threat??
Effects are dose related
Less than 50 mGy is safe
Absorbed fetal dose for all conventional radiographic imaging is less than 50 mGy
“No single diagnostic procedure results in a radiation dose that threatens the well-being of the developing embryo and fetus”
(American College of Radiology)

16. Diagnostic ultrasonography:
Considered to be devoid of embryotoxic effects
Potential side effects
Fetal hyperthermia – with prolonged scans
Post-natal neurobehavioral effects – with repeated exposures
Hande et al. Teratogenic effects of repeated exposures to X-rays and or ultrasound in mice. Neurotoxic Teratol 1995

17. Documented teratogenic drugs (Adapted: ACOG Educational Bulletin )
ACE inhibitors
Lithium
Alcohol
Mercury
Androgens
Phenytoin
Antithyroid drugs
Vitamin A derivatives
Carbamazepine
Streptomycin/kanamycin
Chemotherapy agents
Tetracycline
Cocaine
Thalidomide
Coumadin
Trimethadione
Diethylstilbestrol
Valproic acid
Lead

18. FETAL EFFECTS…
Anaesthetic agents and teratogenicity Teratogenic effects of anaesthetic agents are probably minimal to non-existent and have never been conclusively documented

19. FETAL EFFECTS… Safe drugs: I/V induction agents Narcotics
Neuromuscular blockers
Inhalational agents
Local anaesthetics
Drugs of concern:
Nitrous oxide,
BZD

20. FETAL EFFECTS… Nitrous oxide
Animal studies
Weak teratogen in rodents
Interferes with function of methionine synthetase by oxidation of vitamin B12
decreased THF
decreased DNA synthesis
Decreased uterine blood flow : prevented by addition of halogenated inhalational agents

21. FETAL EFFECTS… Nitrous oxide…
Human studies
No proved teratogenicity
Significant exposure for prolonged duration results in altered enzyme activity
No teratogenic effects in clinically administered dose.

22. FETAL EFFECTS… BENZODIAZEPINES (BZD)
Earlier retrospective studies:
Association between maternal diazepam ingestion during 1st trimester and infant with cleft lip and palate
Later prospective studies:
- No higher risk when used in 1st trimester
Long term maternal administration – fetal BZD dependence & withdrawal
Peripartum administration
– Fetal hypotonia, hypothermia, respiratory depression, feeding difficulties

23. FETAL EFFECTS…
A single shot of short acting BDZ or Nitrous oxide in clinically administered anaesthetic concentration is unlikely to have any teratogenic effects

24. FETAL EFFECTS… BEHAVIORAL TERATOLOGY
Behavioral abnormality in absence of any observable morphological changes
CNS is specifically sensitive during period of major myelination which extends from 4th IU month to 2nd postnatal month
Animals prenatal administration of systemic drugs e.g., Barbiturates, meperidine, promethazine & halothane behavioral changes
Human implication remains unknown

25. FETAL EFFECTS…
“There are not adequate data to extrapolate the animal finding to humans”
(Anesthetic & Life Support Drug advisory Committee of US FDA)

26. Fetal effects…
To summarize, anaesthesia and surgery are associated with higher incidence of abortion, IUGR and perinatal mortality.
These adverse outcomes can often be attributed to the procedure, the site of the surgery (e.g., proximity to the uterus), and/ or the underlying maternal condition
No evidence that anaesthesia results in overall increase in congenital abnormality
No evidence of clear relation between outcome and type of anaesthesia
EFFECT OF ANAESTHESIA ON FOETUS

27. KEY AREAS Normal alterations in maternal physiology during pregnancy
The potential fetal effects from anaesthesia and surgery
Maintenance of uteroplacental perfusion and fetal oxygenation
Practical considerations
Importance of maternal counselling and reassurance
Special situations
OPTIMAL ANAESTHETIC MANAGEMENT OF THESE PREGNANT PATIENTS AND THEIR FETUSES REQUIRES AN UNDERSTANDING OF THESE KEY AREAS

28. Uteroplacental perfusion and fetal oxygentation
Fetal oxygenation depends on maternal oxygen delivery and uteroplacental perfusion
Most serious risk during nonobstetric surgery is Intrauterine asphyxia
Maintenance of fetal well being :
Maternal oxygenation
Maternal carbon dioxide tension
Uterine blood flow

29. Uteroplacental perfusion and fetal oxygentation…
Maternal oxygenation:
Severe maternal hypoxia can occur with:
difficult / oesophageal intubation
pulmonary aspiration
total spinal anaesthesia
systemic LA toxicity
Moderate hyperoxia improves fetal oxygenation and is not associated with intrauterine retrolental fibroplasia and premature DA closure
Any complication LIKE CAN cause profound maternal hypoxemia and is a potential threat to the fetus.. On contrary

30. Uteroplacental perfusion and fetal oxygentation…
Maternal CO2:
Fetal CO2 correlates to maternal levels
Maternal hyperventilation can results in
Umbilical artery constriction
Alkalosis:
shift maternal oxyhemoglobin dissociation curve to left.
Hypocapnia:
↑ ventilation  ↓ venous return ↓ cardiac output  ↓ uterine blood flow.

31. Factors affecting the Uteroplacental perfusion
Maternal hypotension
deep levels of anaesthesia
high levels of spinal or epidural blockade
aortocaval compression,
hemorrhage/ hypovolumia
Anaesthetic agents causing uterine vasoconstriction or hypertonus
(eg. ketamine>2mg/kg, toxic doses of LA)
Catecholamines
Pain, anxiety, light anaesthesia  increased plasma catecholamines decreased UBF
Factors directly REDUCING UBF…………uterine hypertonicitydecrease uterine blood flow
volatile anaesthetic agents: low conc.uterine relaxation & vasodilation maintain UBF
high conc.falling cardiac outputprogressive fetal hypoxia & acidosis

32. KEY AREAS Normal alterations in maternal physiology during pregnancy
The potential fetal effects from anaesthesia and surgery
Maintenance of uteroplacental perfusion and fetal oxygenation
Practical considerations
Importance of maternal counselling and reassurance
Special situations
OPTIMAL ANAESTHETIC MANAGEMENT OF THESE PREGNANT PATIENTS AND THEIR FETUSES REQUIRES AN UNDERSTANDING OF THESE KEY AREAS

33. PRACTICAL CONSIDERATIONS
Timing of surgery
Fetal monitoring
Full stomach precautions
Left uterine displacement
Anaesthetic considerations
Tocolytic agents

34. PRACTICAL CONCERNS… When to do the surgery??
Depends on the balance between maternal and fetal risk and urgency of the surgery
1st trimester – Organogenesis
Increased fetal risk for teratogenesis and abortion
3rd trimester – Peak of physiological changes of pregnancy
Increased maternal risk
Increased risk of preterm labour
Thus 2nd trimester is considered to be a ideal time for non emergency, essential surgeries

35. PRACTICAL CONCERNS… When to do the surgery??
Carvalho B, Anesth Analg Suppl IARS

36. PRACTICAL CONCERNS… Fetal monitoring
Intermittent or continuous FHR monitoring should be considered for major surgical procedures whenever technically feasible:
Ease of monitoring
Type & site of surgery (difficult during abdominal surgery)
Gestational age (after wks)
Tool to monitor intrauterine fetal well being
Done by transabdominal doppler or vaginal doppler probe
Requires the presence of a trained practitioner to monitor and interpret the tracing
Transabdominal monitoring may not be possible during abdominal surgeries or when the mother is obese so vaginal doppler probe may be used in selected patients

37. Good indicator of fetal well being after 25-27 wks
FHR variability
Good indicator of fetal well being after wks
Loss of beat to beat variability and decreased baseline FHR are common – Anaesthetic agent administration
Declerations suggests fetal hypoxemia
Causes of FHR declerations Inadvertent maternal hypoxemia, or inadequate uterine perfusion  evaluation of maternal position, B.P, oxygenation, acid base status and inspection of surgical sites as retractors may impair uterine perfusion.

38. PRACTICAL CONCERNS… Anaesthetic considerations in1st Trimester
Maternal
↑ oxygen requirement
Modified drug pharmacokinetics
Careful airway manipulation
Fetal
Risk of teratogenicity
Impaired UBF

39. PRACTICAL CONCERNS…
Anaesthetic considerations in 2nd and 3rd trimester
Maternal
Prone to hypoxia
Aspiration prophylaxis
Preparation for difficult airway
Increased risk of thromboembolic complications
Avoid hyperventilation

40. PRACTICAL CONCERNS... Fetal Surgery related Premature labour / IUGR
Intrauterine asphyxia
Surgery related
Disease related problem
Diagnostic difficulties
Prolonged exposure to anaesthetics
Surgical manipulations – ↑ fetal risk
Anatomic and surface landmarks unreliable
Diagnostic difficulties as nausea, vomiting, constipation and distension are commmon symptoms of normal pregnancy and abdominal pathology, second increase TLC, Thirdly difficulty in performing radiology

41. PRACTICAL CONCERNS…. DIAGNOSTIC DIFFICULTY
As nausea, vomiting, constipation, and distention are common symptoms of both normal pregnancy and abdominal pathology
Increase WBC count
Reluctance to perform necessary studies involving radiation
Anatomic and surface landmarks can be unreliable
Because of these diagnostic difficulties, the disease (e.g., intrabdominal pathology) may be advanced at the time of surgery

42. PRACTICAL CONCERNS… TOCOLYTICS AGENTS
Prophylactic use in nonobstetric surgery is controversial
May be considered
abdominal surgeries involving uterine manipulations or
Surgeries with high risk of premature labour i.e., cervical encirclage
Uterine contractions should be monitored during the surgery and tocolytic therapy to be instituted if required
Not recommended at or after 34 wks
Do not affect the outcome

43. PRACTICAL CONCERNS… Tocolytic agents
Drugs
Side effects
ß2 agonist
Terbutaline
Ritodrine
Isoxsuprine
fetal tachycardia, hypoglycemia, hypotension,
Pulmonary edema, myocardial ischemia
Calcium channel blockers
Nifedipine
(one of the most commonly used)
transient hypotension
Magnesium sulphate
least commonly used
interaction with NMBs, CNS depression
Indomethacin
peptic ulcer, thrombocytopenia,
premature closure of D.A.
Atosiban
(newer agent)
oxytocin antagonist
Blunts Ca2+ influx in myometrium and inhibit contractility

44. KEY AREAS Normal alterations in maternal physiology during pregnancy
The potential fetal effects from anaesthesia and surgery
Maintenance of uteroplacental perfusion and fetal oxygenation
Practical considerations
Importance of maternal counselling and reassurance
Special situations
OPTIMAL ANAESTHETIC MANAGEMENT OF THESE PREGNANT PATIENTS AND THEIR FETUSES REQUIRES AN UNDERSTANDING OF THESE KEY AREAS

45. Counselling and reassurance
Patient should be reassured about the safety of anaesthesia and the lack of documented associated teratogenicity
Warned about the increased risk of 1st trimester miscarriage and premature delivery in later trimesters
Educate the patient about the symptoms of premature labour and reinforce the need of left uterine displacement
Documentation of details of the risk discussed should be maintained in patients records

46. ANAESTHETIC MANAGEMENT

47. Pre-anaesthetic preparation..
Counselling and reassurance
Consult obstetrician & discuss about the use of tocolytics
Overnight fast
Aspiration prophylaxis
Anxiolytic premedication- to allay anxiety and apprehension
Transport in left lateral position
O.T. preparation – drugs, machine, difficult airway cart, suction and monitors
Anxiolysis as it can decrease UBF

48. ANAESTHETIC MANAGEMENT… Choice of Anaesthesia
Choice of Anaesthetic technique depends on-
Patient’s present surgical status (site and nature of surgery)
Present gestational age of the fetus
Pregnancy induced physiological changes
Other coexisting comorbidities
No technique has been proven to have superiority over the other in fetal outcomes
Regional techniques may be preferable
Safe anaesthetic management is more important than particular agent or technique

49. AIM :
To maintain oxygenation, normotension, eucapnia and euglycemia

50. ANAESTHETIC MANAGEMENT… Monitoring
Maternal monitoring:
Noninvasive / invasive blood pressure
Electrocardiography
Pulse oximetry
Capnography
Temperature monitoring
Use of peripheral nerve stimulator
Blood glucose levels
Fetal monitoring:
External doppler device (FHR )
Tocodynamometer (Uterine contractility)
Glucose levels during prolonged surgery or patients GDM

51. ANAESTHETIC MANAGEMENT… ..
General anaesthesia
Maintain left uterine displacment
Preoxygenation
Rapid sequence induction (Thiopent. sod. & succinyl choline, cricoid pressure  tracheal intubation using cuffed E.T. tube)
Maintenance : A moderate conc. of inhalational agent ( ≤ 2 MAC) with high conc. of oxygen (FiO2 = 0.5) is recommended.
The use of nitrous oxide should be limited during extremely long operations in first trimester by giving high conc of oxygen
Inhalational agents decreases uterine tone and inhibits contractions, in concentrations below 2 MAC TO PREVENT FALL IN CO

52. Opioids and induction agents decreases FHR variability to greater extent than volatile agents
Positive pressure ventilation may reduce UBF
Avoid hyperventilation
Patients on magnesium for tocolysis – reduce dose of NMBs
Reversal agent to be given slowly (increased release of Ach increased uterine tone and preterm labour)
Extubation when fully awake after return of protective airway reflexes

53. ANAESTHETIC MANAGEMENT..…
Regional anaesthesia
Advantages:
Minimal fetal drug exposure
Avoidance of complications of general anaesthesia
If no sedative or narcotics are supplemented – no change in FHR variations to confuse interpretation
Post operative analgesia

54. Management of regional anaesthesia
Pre-op preparation and monitoring same as of General anaesthesia
Reduced LA requirement / ↑ LA Toxicity
Careful aspiration and test dose
Avoid hypotension i.e., adequate preloading, maintain left uterine tilt, choice of vasopressor
Patients on magnesium are more prone to hypotension, often resistant to treatment with vasopressors

55. ANAESTHETIC MANAGEMENT… Postoperative management
Oxygenation in left uterine tilt
Vitals monitoring
Obstetrician consultation for FHR & uterine activity monitoring
Pediatric consultation in case of premature labour
Adequate pain relief – reduce the risk of premature labour
Tocodynamometry is useful in high risk patients as postoperative analgesia may mask awareness of early contractions and delay tocolysis
Early mobilization or DVT prophylaxis if required

56. ANAESTHETIC MANAGEMENT… Postoperative Pain management
Painincreased endogenous catecholamines uterine vasoconstrictiondecreased UBFintrauterine hypoxia
Techniques: Nerve blocks
Local infiltration
Opioids
NSAID
NSAIDS 
1st and 2nd trimester - safe
3rd trimester - risk of premature closure of DA,
Pulm HTN, delayed labour
NSAID can be used before 32 wks and
Acetaminophen is safe

57. ANAESTHETIC MANAGEMENT…
Recommendations approved by American Society of Anaesthesiologists (ASA) and American College of Obstetricians and Gynecologists (ACOG) 2011
No currently used anaesthetic agents have been shown to have any teratogenic effects in humans when using standard concentrations at any gestational age
Fetal heart rate monitoring may assist in maternal positioning and cardiorespiratory management, and may influence a decision to deliver the fetus

58. Recommendations…
It is mandatory to obtain an obstetric consultation before performing any non obstetric surgery or any invasive procedures
A pregnant woman should never be denied indicated surgery, regardless of trimester.
Elective surgery should be postponed
If possible, non-urgent surgery should be performed in the second trimester when preterm contractions and spontaneous abortion are least likely.

59. KEY AREAS Normal alterations in maternal physiology during pregnancy
The potential fetal effects from anaesthesia and surgery
Maintenance of uteroplacental perfusion and fetal oxygenation
Practical considerations
Importance of maternal counselling and reassurance
Special situations
OPTIMAL ANAESTHETIC MANAGEMENT OF THESE PREGNANT PATIENTS AND THEIR FETUSES REQUIRES AN UNDERSTANDING OF THESE KEY AREAS

60. Special situation – Laparoscopy
No longer a contraindication in pregnant patients
Concerns:
- Uterine and fetal trauma
- Fetal acidosis from absorbed carbon dioxide.
- Decreased maternal cardiac output and uteroplacental perfusion due to increased abdominal pressure.

61. Special situation – Laparoscopy
Guidelines by Society of American Gastrointestinal Endoscopic Surgeons (SAGES) 2008
Safe during any trimester of pregnancy
Obtain preoperative obstetrician consultation
Intermittent lower extremity pneumatic compression devices to prevent venous stasis
The fetal heart rate and uterine tone should be monitored in both preoperative and postoperative periods
End tidal CO2 should be maintained

62. Special situation – Laparoscopy
Left uterine displacement should be maintained
An open (Hassan) technique, a veres needle or an optical trocar technique to enter abdomen
Low pneumoperitoneum pressures (10-15mm Hg) should be used
Tocolytic agents should not be used prophylactically but should be considered when evidence of preterm labour is present

63. Special situation – Fetal surgery
Anaesthetic considerations remains similar to those of non obstetric surgeries
Two surgical patients
Maternal safety is important
Choice of anaesthetic technique
Minimally invasive endoscopic procedure – Neuraxial anaesthesia
Open intrauterine procedures – General anaesthesia

64. Special situation – Fetal surgery….
Important considerations
Consider anaesthetic requirement of fetus including amnesia, analgesia and immobilty
Control of uterine tone is essential
More intensive intraop FHR monitoring

65. Special situation – Electroconvulsive Shock Therapy
Used to treat major depression and BPD during pregnancy when rapid control of symptoms is needed
Advantage –
Avoids potential teratogenicity from psychotropic medications
Not a risk factor for premature labour, miscarriage or stillbirth
Anaesthetic management
Confirm the absence of uterine contractions using tocodynamometry before and after ECT
Monitor FHR before and after ECT

66. Special situation – Neurosurgery (e.g., Aneurysm, AV malformation)
Hypotensive anaesthetic techniques ( 25 – 30% reduction in SBP or mean BP less than 70 mmHg) can cause decrease in UBF
Dose (less than 0.5 mg/kg/hr) and duration of Sodium Nitroprusside should be limited
FHR monitoring should be performed continuously specially if induced hypotension or hyperventilation is planned so that necessary adjustments can be made if fetal distress occurs
Hypovolemia and very large doses of mannitol should be avoided as they cause fetal dehydration
Endovascular treatments – uterine shielding during periods of radiation

67. Special situation – Trauma during pregnancy
Trauma is the leading cause nonobstetric cause of morbidity and mortality
Primary management goals are similar to the care of nonpregnant trauma cases
Avoidance of hypoxia, hypotension, acidosis and hypothermia are important for the maintenance of UBF and fetal well being
More prone to develop pulmonary edema
In stable patients without ongoing blood loss – Conservative fluid management
CVP monitoring should be considered if renal insufficiency or fluid overload occurs

68. Special situation – Trauma during pregnancy…
Primary aim should be optimization of the mother and the obstetric management is planned later
No radiological tests should be withheld because of fetal concerns, uterus should be shielded during radiation procedures
Indications for an Emergency Cesarean delivery in a pregnant trauma patients
Traumatic uterine rupture
Stable mother with viable fetus that is in distress
An unsalvagable mother who still has a viable fetus
A gravid uterus that is interfering with intraoperative surgical repair

69. References
Obstetric Anaesthesia, Principles and Practice. David H Chestnut, 4th Ed
Miller’s anesthesia. Ronald D Miller. 7th ed.
Wylie and Churchill Davidson’s ‘A Practice of Anaesthesia’ 7th ed.
Clinical Anesthesia; Barash, Cullen, Stoelting, 6th edition
Yao & Artusio’s Anesthesiology. 7th edition
Nonobstetric surgery during pregnancy, ACOG committee opinion, No. 474, Feb 2011
Roisin Ni M, David A. Anesthesia on pregnant patients for nonobstetric surgery. Journal of clinical anesthesia (2006) 18, 60-66

70. Thank You