Pregnancy and Anaesthesia

1. ANAESTHESIA FOR NON-
OBSTETRIC SURGERY IN
PREGNANCY
PRESENTER- DR NANDINI
DESHPANDE
GUIDE- DR SHOBHA PARASHAR

2. • The American College of Obstetrician and Gynecologists’ Committee
on Obstetric practice acknowledges that the issue of non-obstetric
surgery during pregnancy is an important concern for physicians
who care for women. It is important for a physician to obtain an
obstetric consultation before performing non-obstetric surgery and
some invasive procedures (e.g; Cardiac catheterization or
Colonoscopy) because obstetricians are uniquely qualified to discuss
maternal physiology and anatomy that may affect intraoperative
maternal- foetal wellbeing.
• The American College of Obstetrician and Gynecologists
Committee Opinion. Number 474. February 2011. Reaffirmed 2013 .

3. Issues approved by American Society of
Anesthesiologists (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 .
• Foetal heart rate monitoring may assist in maternal
positioning and cardiorespiratory management, and may
influence a decision to deliver the foetus.
• Surgery should be done at an institution with neonatal and
paediatric service.

4. GUIDELINES:
• A pregnant woman should never be denied indicated
surgery, regardless of the 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 .
Non-obstetric surgery during pregnancy, ACOG committee
opinion, No. 474, Feb 2011, Reaffirmed 2013

5. INCIDENCE:
• 0.75% to 2% of pregnant women undergo surgeries
• Annual incidence - 75,000 – 80,000 (USA)
• Centralized data unavailable in India
• Most common indication - Acute abdominal infections ,
Appendicitis (1:2000) , Cholecystitis (8:10 000)

7. SURGERIES IN PREGNANCY:
• Directly related to pregnancy - e.g. Cervical
encirclage
• Indirectly related to pregnancy - e.g. Ovarian
Cystectomy
• Not related to pregnancy - e.g.
Appendicectomy[MOST COMMON], Intestinal
obstruction

8. OUR ROLE AS AN ANAESTHETIST??
• Anaesthesiologist who care for pregnant patient
undergoing non-obstetric surgery must provide safe
anaesthesia for both mother & foetus.
• To maintain maternal safety the physiological &
anatomical changes of pregnancy must be considered,
anaesthetic technique & drug administration modified
accordingly.
• Foetal wellbeing is related to avoidance of foetal asphyxia
& teratogenic drugs & preterm labour.

9. GOALS:
1. Optimization & maintenance of normal maternal physiological
function.
2. Optimization & maintenance of uteroplacental blood flow & O2
delivery.
3. Avoidance of unwanted drug effects on the foetus.
4. Avoidance of stimulating myometrium.
5. Avoidance of awareness during GA.
6. Using regional anaesthesia , if possible.
7. To prevent hypotension, hypovolemia, hypoxia and hypothermia

10. Safe anaesthesia in
pregnancy
Understanding the altered
pharmacology
Proper
counselling of
the parturient
and family
Understanding
maternal and
foetal
physiology

11. PHYSIOLOGICAL CHANGES DURING
PREGNANCY & ANAESTHETIC IMPLICATIONS:

12. SYSTEM PHYSIOLOGICAL
CHANGES
ANAESTHETIC
IMPLICATIONS
CARDIOVASCULAR
SYSTEM
↑ in CO up to 50%
↑ in Uterine perfusion Uterine perfusion not
autoregulated
↓ SVR, ↓ PVR Hypotension common
under regional and
general anaesthesia
Aortocaval compression
occurs from 13 weeks
Supine hypotension
syndrome requires left
lateral tilt

13. SYSTEM PHYSIOLOGICAL
CHANGES
ANAESTHETIC
IMPLICATIONS
RESPIRATORY ↑ Minute ventilation Faster inhalation induction
Respiratory alkalosis (PaCO2
3.7–4. 2 kPa)
Maintain PaCO2 at normal
pregnancy
↓ ERV, ↓ RV, ↓ FRC ↑ V/Q
mismatch
↑ Oxygen consumption
Upward displacement of
diaphragm
Potential hypoxaemia in the
supine position
↑ Thoracic diameter Breathing more diaphragmatic
than thoracic
Mucosal oedema Difficult laryngoscopy and
intubation; bleeding during

14. SYSTEM PHYSIOLOGICAL
CHANGES
ANAESTHETIC
IMPLICATIONS
CNS ↑ Epidural veins Bloody tap more common
engorgement
↓ Epidural space volume More extensive local
anaesthetic spread
↑ Sensitivity to opioids
spread
and sedatives
HAEMATOLOGICAL
SYSTEM
↑ Red cell volume 30%, ↑
WCC
↑Plasma volume 50% Dilutional anaemia
↑ Coagulation factors Dilutional anaemia
↓ Albumin and colloid
osmotic pressure
Oedema , decreased protein
binding of drugs

15. SYSTEM PHYSIOLOGICAL
CHANGES
ANAESTHETIC
IMPLICATIONS
GASTROINTESTINAL
SYSTEM
↑ Intragastric pressure Aspiration risk
↓ Barrier pressure Antacid prophylaxis, RSI
after 18
weeks gestation
RENAL SYSTEM ↑ Renal plasma flow
Normal urea and
creatinine may mask
↑ GFR impaired renal function
↓ Reabsorptive capacity Glycosuria and
proteinuria

18. COUNSELLING & REASSURANCE:
1. Patient should be reassured about the safety of
anaesthesia and the lack of documented associated
teratogenicity.
2. Warned about the increased risk of 1st trimester
miscarriage and premature delivery in later trimesters .
3. Educate the patient about the symptoms of premature
labor and reinforce the need of left uterine displacement .
4. Documentation of details of the risk discussed should be
maintained in patients records .

19. FOETAL CONSIDERATIONS:
Risks
of
foetu
s
Disease process/therapy
related
Teratogenicitiy
Abortion/Pre-term
delivery
Perturbation of
uteroplacental
circulation

20. TERATOGENICITY:
• Teratogenicity is defined as the observation of any significant
change in the function or form of a child secondary to prenatal
treatment .
• Between 31st -71st days of gestation, period of organogenesis, the
embryo is most vulnerable to teratogenic effects .

21. ANAESTHETIC AGENTS & TERATOGENICITY:
1. Anaesthetic agents like propofol, barbiturates, opioids, inhalational
agents, neuromuscular blocking agents and local anaesthetics are
safe in pregnancy .
2. Association between BZD and craniofacial defects and cardiac
anomalies are debated .
3. Benzodiazepines (BZD) are not teratogenic and a single dose
appears safe but use in the first trimester should be avoided .
4. 50% N2O has weak teratogenic effects in rodents when used for
more than 24 hours .
5. Current evidence does not support withholding N2O in clinical
practice

22. BENZODIAZEPINES/OPIOIDS:
• Benzodiazepines/minor tranquilizers: associated with
increased anomalies. BZD’s initially associated with
increased cleft palate.
• FDA: minor tranquilizer should almost be avoided in 1st
trimester.
• Single dose: no effect
• Synthetic opioids: Animal studies not teratogenic.

23. MUSCLE RELAXANTS & LOCAL ANAESTHETICS:
• Muscle relaxants: minimal placental transfer.
• LA(local anaesthetics): no evidence of problem in human.
• Cocaine: is a known teratogen. IUGR, preterm delivery, &
increased risk of abruptio placenta.

24. INDUCTION AGENTS:
• Ketamine: not teratogenic but >1mg/kg- increased risk of
preterm labour.
• Thiopental Na: not teratogenic in conventional doses.
• Propofol: no adverse foetal effects compared to thiopental.
• Propofol+ Succinylcholine may cause severe maternal
bradycardia.

25. NITROUS OXIDE [N2O]:
• Theoretical risk is decreased but reversible DNA synthesis.
• Pretreatment with folinic acid is not proven effective in
preventing neurogenic teratogenicity in animal.
• Conclusion: teratogenic only under extreme condition.
• However slightly increased abortion risk.

26. INHALATIONAL AGENTS:
• Volatile anaesthetics: shows teratogenecity in some
species.
• Volatile anaesthetics & N2O in rats showed no anomaly at
any gestational age.
• Like N2O , slightly increased risk of abortion.

29. PREVENTION OF PRE-TERM LABOUR:
• Surgery, especially intra-abdominal procedures, increases the risk of
preterm labor or abortion.
• Perioperative FHR & HR variability monitoring may be helpful but
controversial .
• Prophylactic tocolytic therapy considered in the third trimester in
abdominal surgeries involving uterine manipulations or surgeries
with high risk of premature labor i.e. cervical encirclage .
• Tocographic monitoring during the first hours or days
postoperatively to detect and treat preterm labor as early as
possible .

30. TOCOLYTIC DRUGS & MATERNAL &FOETAL SIDE
EFFECTS:
Tocolytic agent Maternal side effects Foetal side effects
Magnesium Hypotension and Cardiovascular
collapse, pulmonary edema,
sensitivity to NDMR
Loss of beat to beat variability
Beta-adrenergic drugs Tachycardia, ↓ed SVR,
hypokalemia, pulmonary
oedema
Foetal tachycardia
Nitroglycerine ↓ed preload with hypotension,
pulmonary edema
Prostaglandin inhibitors Prolonged bleeding time Premature closure of PDA
Atosiban ( oxytocin antagonist) Blunts Ca2+ influx in
myometrium and inhibit
contractility

31. UTEROPLACENTAL PERFUSION & FOETAL
OXYGENATION:
• Most serious risk during non-obstetric surgery is
Intrauterine asphyxia.
• Foetal oxygenation depends on maternal oxygen delivery
and uteroplacental perfusion.
• Maintenance of foetal well being :
1. Maternal oxygenation
2. Maternal carbon dioxide tension
3. Uterine blood flow

32. AVOIDANCE OF FOETAL HYPOXIA:
• Prolonged maternal hypoxaemia → uteroplacental vasoconstriction →
reduced uteroplacental perfusion → foetal hypoxaemia → acidosis → foetal
death.
• Excessive positive pressure ventilation → maternal hypocapnia → increased
intrathoracic pressure → reduced venous return → reduced uterine blood flow.
• Maternal hypotension of any cause should be treated immediately with IV
fluids, vasopressors, blood products and adjustments of ventilation and
position.
• Hypocapnia results in uterine vasoconstriction → a shift in the maternal
oxyhaemoglobin dissociation curve to the left → reduced oxygen release to
the foetus
• Hypercapnia → foetal acidosis → myocardial depression → death.
• Uterine hypertonus → increased uterine vascular resistance → decreased
blood flow .

33. FOETAL MONITORING:
• Monitoring of FHR from 18-22 weeks and HR variability
from 25 weeks onwards requires a skilled interpretation.
• Difficulty in continuous monitoring & interpretation in
both baseline FHR & HR variability.
• Cardiotocography (CTG) monitoring used in viable foetus.
• Monitoring enables optimization of maternal condition in
signs of foetal compromise.

36. WHEN TO DO THE SURGERY??
• It depends on balance between maternal and foetal risk
urgency of the surgery.
• 1st trimester – Organogenesis . Increased foetal risk for
teratogenesis.
• 3rd trimester – Peak of physiological changes of pregnancy
Increased maternal risk.
• Thus 2nd trimester is considered to be a ideal time for
non emergency, mandatory surgeries.

38. ANAESTHETIC CONSIDERATIONS IN 1ST
TRIMESTER:
• Maternal
1. ↑ oxygen requirement
2. Modified drug pharmacokinetics
3. Careful airway manipulation
• Foetal
1. Risk of teratogenicity
2. Impaired uterine blood flow

39. IN 1ST & 2ND TRIMESTER:
•Maternal
1. Aortocaval compression
2. Prone to hypoxia
3. Aspiration prophylaxis
4. Preparation for difficult airway
5. Avoid hyperventilation
6. Increased risk of thromboembolic complications

40. •Foetal
1. Premature labour / IUGR
2. Intrauterine asphyxia
•Surgery related
1. Disease related problem
2. Diagnostic difficulties
3. Prolonged exposure to
anaesthetics
4. Surgical manipulations –
↑ foetal risk
5. Anatomic and surface
landmarks unreliable

41. PRE- ANAESTHETIC CHECKUP & PREPARATION:
• Evaluation, Counselling and Reassurance
• Attention to be paid to airway examination
• Routine investigations, adequate arrangement of blood for major
surgical intervention
• Consult obstetrician & discuss about the use of tocolytics
• Overnight fasting for 6- 8 hours
• Aspiration prophylaxis with H2-receptor antagonists and
nonparticulate antacids
• Anxiolytic premedication- to allay anxiety and apprehension
• Transport in left lateral position
• O.T. preparation – drugs, machine, difficult airway cart, suction and
monitors

42. EFFECTS OF ANAESTHESIA ON MOTHER & FOETUS:

43. CHOICE OF ANAESTHESIA???
• Choice of Anaesthetic technique depends on-
1. Patient’s present surgical status (site and nature of surgery)
2. Present gestational age of the foetus
3. Pregnancy induced physiological changes
4. Other coexisting comorbidities
• No technique has been proven to have superiority over the other in foetal
outcomes
• Regional techniques may be preferable
• Safe anaesthetic management is more important than particular agent or
technique

44. MONITORING:
BP,HR,RR
ECG
sp02ETCO2
FHR

45. GENERAL ANAESTHESIA:
• Maintain left uterine displacement to prevent aortocaval
compression
• Preoxygenation
• Rapid sequence induction (Thiopental sod. & succinylcholine,
cricoid pressure -tracheal intubation using cuffed E.T. tube)
• Maintenance : Muscle relaxant, an opioid and/ or 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 concentration
of oxygen

46. • Opioids and induction agents decreases FHR variability to
greater extent than volatile agents .
• Ketamine increases uterine tone (in early pregnancy) and
should not be used .
• Positive pressure ventilation may reduce UBF.
• Avoid hyperventilation to maintain end tidal CO2 in normal
pregnancy range.
• 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.

47. •Advantages
1. Definitive
2. Easy to titrate the depth
3. Best uterine relaxation
4. Risk of meningitis and PDPH eliminated
5. High level of haemodynamic stability

48. •Disadvantages
1. Possible teratogenic effect
2. Maternal risk of aspiration
3. High incidence of post op pain, nausea and
vomiting
4. Difficult intubation

49. ALOGARITHM FOR DIFFICULT OBSTETRIC
INTUBATION

51. REGIONAL ANAESTHESIA[SPINAL]:
Advantages:
• Minimal foetal 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
• Reduced LA requirement / LA Toxicity
• Careful aspiration and test dose

52. • 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
• Disadvantages: Hypotension, sometimes profound
1. Non rectifiable dermatomal level
2. PDPH
3. Limited post op analgesia as compared to epidural
4. More incidence of nausea/vomiting

53. EPIDURAL ANAESTHESIA
•Advantages :
1. Minimal risk of severe hypotension
2. Rectifiable dermatomal level
3. Excellent post op analgesia
4. Risk of meningitis and PDPH eliminated
5. High level of haemodynamic stability

54. •Disadvantages :
1. Procedure is more complex/skilled
2. Onset of action is slower
3. Amount of local anaesthetic required is more
4. Higher incidence of failure/partial action/sparing
5. Less profound block

55. POST-OPERATIVE MANAGEMENT:
• Oxygenation in left uterine tilt
• Vitals monitoring
• Obstetrician consultation for FHR & uterine activity monitoring
• Paediatric consultation in case of premature labour
• Adequate pain relief with Nerve block, Local infiltration, Opioids,
NSAIDs
• 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
• NSAIDs can be used before 32 weeks and Acetaminophen is safe

56. SPECIAL SITUATIONS

57. LAPROSCOPY IN PREGNANCY
• It is no longer considered to be a contraindication to laparoscopic surgery
• Concerns in Laparoscopic surgeries :
1. Pneumoperitoneum with trendelenberg position
2. Reduced lung compliance and FRC
3. Increased airway pressures
4. Hypoxia in advanced gestation.
• Pneumoperitoneum with reverse trendelenberg position
1. Significant aorto venacaval compression
2. Reduced venous return & hypotension.
• Pregnancy is a prothrombotic state
1. Lower extremity venous stasis due to pneumoperitoneum - higher risk of
thromboembolism

58. RECOMMENDATIONS FOR LAPROSCOPY:
1. Use an open technique to enter the abdomen to avoid potential
uterine or foetal trauma.
2. Monitor maternal end-tidal CO2 (30–35 mmHg range) arterial
blood gas (if the procedure is prolonged) to avoid foetal
hypercarbia and acidosis
3. Maintain low pneumoperitoneum pressures (8–12 mm Hg, not 15
mm Hg)
4. Minimize insufflation time or use a gasless technique to avoid
decreases in uteroplacental perfusion
5. Protect the uterus with lead shielding during intraop radiological
procedures (Cholangiography

59. 6. Limit the extent of Trendelenburg and reverse
Trendelenburg positions. Initiate any position
changes slowly. Left lateral tilt is to be
maintained.
7. Pneumatic stockings to be used
8. Monitor fetal heart rate and uterine tone
when

60. NEUROSURGERY IN PREGNANCY
Indications :
1. Subarachnoid haemorrhage
2. Intracranial haemorrhage
3. Acute traumatic brain injury
4. Primary or metastatic brain tumour
• All neurosurgical procedures during pregnancy must be
considered as major interventions

62. • Aneurysm clipping may be needed during pregnancy.
• Meningiomas have steroidal receptors, it increases in
size during pregnancy due to vascular proliferation
and increased intravascular volume.
• Foetal monitoring is necessary when blood loss,
large volume shifts and hypotension is expected .
• Placental circulation has poor autoregulation. It
depends on systemic pressure.
• Reduction in systolic pressures > 20-30% or MAP<70
mmHg, reduces placental blood flow.

63. • SNP in doses > 0.5mg/kg/hr can cause cyanide
toxicity in the foetus. NTG is a safer option.
• Maternal hyperventilation and resultant hypocarbia
(pCO2 < 25mmHg) shifts the oxyhaemoglobin curve
to the right and hampers foetal oxygenation.
• Osmotic diuresis can lead to foetal dehydration.
• Endovascular procedures abolish the need for
craniotomy. Foetal shielding during the procedure is
necessary .

64. TRAUMA IN PREGNANCY:
• Incidence : 8% of all pregnancies
• Type: 1) Blunt , 2) Penetrating
• Effects
1. Direct foetal injuries
2. Placental abruption
3. Pre-term labour
4. Massive foeto-maternal haemorrhage
5. Uterine rupture
6. Foetal loss

65. • Among the leading causes of maternal mortality/morbidity
• Maternal life takes precedence over foetal life.
• Primary management goals (Fluid resuscitation/Airway
management) is similar to non pregnant females.
• Mother should receive all diagnostic tests deemed necessary for her
optimal management, shielding the foetus when possible.
• More prone to pulmonary oedema due to relative hypoproteinemia
& hypervolemia
• Conservative, CVP guided fluid therapy is recommended
• Early USG – Foetal viability, monitoring to continue
• Avoid – Hypoxia, Hypotension, Hypothermia and Acidosis
• Causes of foetal loss – ◦ Maternal mortality ◦ Abruption

66. • Indications for emergency Caesarean section in
pregnant trauma patient:
1. Traumatic uterine rupture
2. Haemodynamically stable mother with foetal
distress
3. Gravid uterus that is interfering with intraoperative
surgical repair

67. CARDIAC SURGERY DURING PREGNANCY:
• Incidence of heart disease in pregnancy : 1-3%
• Incidence of maternal death : 10-15%
• Higher morbidity and mortality with cardiac surgery
• First managed medically
• Surgery reserved for severe decompensation
• Percutaneous balloon valvuloplasty seems to be better
alternative

68. CONDITIONS REQUIRING SURGERY:
•Severe valvular disease
•Aortic aneurysm
•Aortic dissection
•Severe congenital anomaly
•Pulmonary thromboembolism
•Severe coronary artery disease

69. • Four major risk factors predict adverse maternal
outcomes :
1. History of transient ischemic attack, stroke, or arrhythmia
2. NYHA heart failure classification of three or four before
onset of pregnancy
3. Left-heart obstruction (e.g., mitral valve area <2 cm2,
aortic valve area <1.5 cm2, peak left outflow gradient >
30mmHg)
4. Left ventricular (LV) ejection fraction <40%

70. • Complications of cardiac surgery:
1. Pulmonary oedema
2. Arrhythmias
3. Myocardial infarction
4. Stroke
5. Heart failure
6. Death

71. FOETAL PROTECTION STRATEGIES DURING CPB:
• High pump flow rate (>2.5 L min-1 m-2)
• Increased perfusion pressure (> 70 mm Hg)
• Maintenance of maternal haematocrit 28%
• Limit hypothermia(< 32 degree)
• Monitor uterine tone and FHR
• Minimize CPB time
• Consider pulsatile perfusion
• Optimize acid-base, glucose, PaO2 & PaCO2

72. CONCLUSION:
• To check pregnancy tests before anaesthesia & surgery
• To consider maternal risk associated with anatomical & physiological
changes
• To consider foetal risk associated with teratogenicity, UBF & preterm
labor
• Diagnosis of the pathology often become delayed ,increasing the foetal
& maternal risk
• Maternal hypoxia, hypercarbia, hypotension, acidosis may pose greatest
risk to the foetus
• No anaesthetic agent is proved to be teratogenic, N2O may only be
harmful to animals
• It is not clear whether the adverse foetal outcome is due to prolonged
use of anaesthetic or surgery itself
• Laparoscopic surgery is likely to be a useful modality for surgical
intervention
• FHR & CTG monitoring may be useful