Download - Sudip presentation
Non Obstetric Surgery in
Pregnant Patients
Dr. Sudip Kumar Saha
DA student
Department of
Anaesthesiology
SSMCMH, Dhaka
Introduction
Anaesthesiologist who care for pregnant patient undergoing non-obstetric surgery must provide safe anesthesia for both mother & fetus.
To maintain maternal safety the physiological & anatomical changes of pregnancy must be considered, anesthetic technique & drug administration modified accordingly.
Fetal wellbeing is related to avoidance of fetal asphyxia & teratogenic drugs & preterm labour.
Goals of an
Anaesthesiologist Optimization & maintainance of
normal maternal physiological function.
Optimization & maintainance of uteroplacental blood flow & O2 delivery.
Avoidance of unwanted drug effects on the fetus.
Avoidance of stimulating myometrium.
Avoidance of awareness during GA.
Using regional anesthesia , if possible.
Incidence
0.75% to 2% of pregnant women undergo
surgeries
75,000 – 80,000 procedures annually in USA
Centralized data unavailable in Bangladesh
Conditions common to this age group: Ovarian
cysts, appendicitis, cholelithiasis, cervical
incompetence, breast or other
malignancies, traumatic injuries.
Commonest surgery- Appendicectomy.
Incidence
23%
35%
42%
Distribution of surgery according to trimesters
1st Trimester
2nd Trimester
Trimester breakdown of nonobstetric surgery undertaken during pregnancy.
Modified from Mazze RI, Kallen B. Am J Obstet Gynecol 1989;161:1178–85.
Most common surgical procedures
performed in pregnant women
Type of
surgery
1st trimester 2nd trimester 3rd trimester
C.N.S. 6.7% 5.4% 5.6%
E.N.T. 7.6% 6.4% 9.5%
Abdominal 19.9% 30.1% 22.6%
Genitourinary/
Gynaecological
10.6% 23.3% 24.3%
Laproscopic 34.1% 1.5% 5.6%
Orthopaedics 8.9% 9.3% 13.7%
Endoscopy 3.6% 11% 8.6%
Skin 3.8% 3.2% 4.1%
Adapted from Mazze RL, Kallen B: Reproductive outcome after anaesthesia
and surgery during pregnancy: A registry study of 5,405 cases, Am J Obstet
Gynecol 161:1178-1185, 1989
Surgeries in pregnancy
Directly related to pregnancy -
◦ Eg: Cervical encirclage
Indirectly related to pregnancy -
◦ Eg: Ovarian Cystectomy
Not related to pregnancy -
◦ Eg: Appendicectomy, Intestinal
obstruction
4 areas of unique concern
Maternal Safety
Avoidance of
intrauterine asphyxia
Avoidance of
teratogenicdrugs
Prevention of preterm
labour
PHYSIOLOGICAL &
ANATOMICAL CHANGES
DURING PREGNANCY.
Maternal safety
Cardiovascular changes
CO increase in pregnancy by 50% due to combined increase in HR(25%) & SV(30%).
SVR decreased due to oestrogen & progesterone.
ECG changes occur in pregnancy are entirely normal include left axis deviation & ST/T changes. Heart murmur are also common due to turbulence associated with increased blood flow.
RCV increase 35-50%.
Pregnancy is a hypercoagulable state with an increase in most clotting factor. Platelet count fall but an increase in platelet consumption occur.
Pregnancy is a significant risk factor for thromboembolism.
Respiratory & GIT changes:
Oxygen consumption increases upto60% at term.
MV increases early due to an increase in RR & tidal volume &is up by 45%. Increased MV is mediated by progesterone which acts as a respiratory stimulant. Increased MV causes resp. alkalosis.
FRC is decreased in pregnancy. Circulating progesterone reduces the
LOS tone, increasing the incidence of esophageal reflux..
Drugs: altered pharmacokinetics/
pharmacodynamics The MAC of volatile agents is reduced
by 30% under the influence of progesterone.
There is a decrease in plasma cholinesterase level by 25%.
The increased blood volume causes physiological hypoalbuminemia.
The volume of epidural & subarachnoid space is reduced due to the gravid uterus compressing the IVC causing distension of epidural venous plexus.
Remember the following
manoeuverRemembering left lateral tilt to
prevent aortocavalcompression.
Remembering meticulous pre-oxygenation to prevent hypoxia.
Remembering antacid prophylaxis & RSI to reduce
risk of aspiration.
Anaesthesia Considerations
First “Rule of Thumb”
Administer drug to the patient only if benefits
clearly outweigh the risk, both to the mother and
the fetus
Planning the Anaesthesia Regimen
depends on-
1. Patient‟s present surgical status
2. Present gestational age of the fetus
3. Pregnancy induced physiological changes
4. Other coexisting co-morbidities
Emergencies will always outweigh the concern for the fetus
„The parturient is the primary patient‟
The regimen that has been chosen should cater to..
Needs of the Patient„Physical and emotional status of the patient dictates the regimen‟
Needs of the Operating Surgeon„Often the anaesthetic regimen that will optimize the positioning and surgical exposure‟
Needs of the Obstetrician„May need a regimen that causes uterine relaxation‟
Anaesthesia Considerations
Choice of Anaesthesia
Both General and Regional anaesthesiahave been used successfully in pregnant patients.
No technique has been proven to have superiority over the other in fetal outcomes.
Each technique has its own advantages and disadvantages and the selection of technique is based on maternal condition, site and nature of surgery and available resources.
Subarachnoid Block
Advantages Minimal amount of Local Anaesthetics
Rapid onset of anaesthesia
Definitive end point
Easy to administer
Dense Blockade
Disadvantages Hypotension, sometimes profound
Non rectifiable dermatomal level
PDPH
Limited post op analgesia as compared to epidural
More incidence of nausea/vomiting
Epidural Block
Advantages Minimal risk of severe hypotension
Rectifiable dermatomal level
Excellent post op analgesia
Risk of meningitis and PDPH eliminated
High level of haemodynamic stability
Disadvantages Procedure is more complex/skilled
Onset of action is slower
Amount of local anaesthetic required is more
Higher incidence of failure/partial action/sparing
Less profound block
General Anaesthesia
Advantages Definitive
Easy to titrate the depth
Best uterine relaxation
Risk of meningitis and PDPH eliminated
High level of haemodynamic stability
Disadvantages Possible teratogenic effect
Maternal risk of aspiration
High incidence of post op pain, nausea and vomiting
• Most serious risk during non-obstetric surgery is intrauterine asphyxia
• Causes of hypoxia: Difficult intubation, esophageal intubation, pulmonary aspiration, high levels of regional block, systemic local anesthetic toxicity or airway compromise from trauma
• Causes of decreased uteroplacentalperfusion: Aortocaval compression, high level of spinal or epidural blockade, hemorrhage, hypovolemia, hyperventilation, high dose of ά adrenergic agents or increased circulating catecholamines, uterine hypertonus from ketamine >2mg/kg in early pregnancy or toxic doses of local anesthetics.
Effects of anaesthesia on Foetus
Intrauterine foetal asphyxia
Avoided by maintaining the
following variables of foetal respiration-
• Maternal oxygenation
• Maternal CO2 tension
• Uterine blood flow
Consensus Statement
Approved by American Society of Anaesthesiologists (ASA) and American College of Obstetricians and Gynecologists (ACOG) on Oct 21, 2009
The following generalizations have been made: -
1. No currently used anaesthetic agents have been shown to have any teratogenic effects in humans when using standard concentrations at any gestational age.
2. Fetal heart rate monitoring may assist in maternal positioning and cardio-respiratory management, and may influence a decision to deliver the fetus.
Recommendations include..
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 until after delivery.
If possible, non-urgent surgery should be performed in the second trimester when preterm contractions and spontaneous abortion are least likely.
Recommendations for foetal
monitoring include.. Surgery should be done at an institution with neonatal
and pediatric services.
An obstetric provider with cesarean delivery privileges should be readily available.
A qualified individual should be readily available to interpret the fetal heart rate.
General guidelines for fetal monitoring include –
In a previable foetus - ascertain the fetal heart rate by Doppler before and after the procedure.
In a viable foetus - simultaneous electronic fetal heart rate and contraction monitoring, before and after the procedure to assess fetal well-being and the absence of contractions.
The fetus is viable, it is advisable to obtain informed consent to emergency cesarean delivery.
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
When to do the surgery??
Carvalho B, Anesth Analg Suppl IARS
2006
Teratogenecity: general
Fetal risk: 0-15 days- usually
embryotoxic(EGA 2-4 wks)
15-60 days(organogenesis)- great risk
to fetus.
Then functional defecit.
Nearly all drugs have been
demonstrated to be teratogenic in
some species at some dose.
Teratogenecity:
BZD/Opioids BZD/Minor tranquilizer: Associated
with increased anomalies. BZD
initially associated with increased cleft
palate.
FDA: Minor tranquilizer should almost
always be avoided in 1st trimester.
Single dose: no effect.
Synthetic opioids : Animal studies not
teratogenic.
Teratogenecity:
Muscle relaxant & LA Muscle relaxant: minimal placental
transfer.
LA(local anesthetics): no evidence of
problem in human.
Cocaine: is a known teratogen.
IUGR, preterm delivery, & increased
risk of abruptio placenta.
Teratogenecity:
induction agent Ketamine: not teratogenic but
>1mg/kg- increased risk of preterm
labour.
Thiopental Na: not teratogenic in
conventional doses.
Propofol: no adverse fetal effects
compared to thiopental.
Propofol+Succinylcholine may cause
severe maternal bradycardia.
Teratogenecity: N2O
Theoretical risk is decreased but
reversible DNA synthesis.
Pretreatment with folinic acid is not
proven effective in preventing
neurogenic teratogenecity in animal.
Conclusion: teratogenic only under
extreme condition. However slightly
increased abortion risk.
Teratogenecity:
inhalational agent Volatile anaesthetic: shows
teratogenecity in some species.
Volatile anaesthetic & N2O in rats
showed no anomaly at any gestational
age.
Like N2O , slightly increased risk of
abortion.
F.D.A classification of risk of
teratatogenicity of drugs (1979)Category Clinical Implications
Category A Adequate and well controlled studies have failed to demonstrate a
risk to the foetus in the first trimester of pregnancy (and there is no
evidence of risk in later pregnancies)
Category B Animal reproduction studies have failed to demonstrate a foetal risk
but there are no controlled studies in pregnant women, OR animal
reproduction studies have shown an adverse effect, but adequate
well controlled studies in pregnant women have failed to demonstrate
a risk to the foetus in any trimester.
Category C Animal reproduction studies have shown an adverse effect on the
foetus and there are no adequate well controlled studies in humans,
or studies in animals and humans are not available. Potential benefits
of drugs may warrant use of drug in pregnant women despite
potential risks.
Category D There is positive evidence of human foetal risk, but the benefits from
use in pregnant women may be acceptable despite the risk (e.g. life
threatening situation or serious disease for which safer drugs are not
available).
Category X Studies in animals or humans have demonstrated foetal
abnormalities, or evidence based on human experience, and the risk
of use of the drug in pregnant women clearly outweighs any possible
benefit. The drug is contraindicated in women who are or may
become pregnant.
Documented teratogens(Adapted: ACOG Educational Bulletin #236, 1997)
ACE inhibitors Lithium
Alcohol Mercury
Androgens Phenytoin
Antithyroid drugs Radiation (>0.5 Gy)
Carbamazepine Streptomycin/kanamycin
Chemotherapy agents Tetracycline
Cocaine Thalidomide
Coumadin Trimethadione
Diethylstilbestrol Valproic acid
Lead Vitamin A derivatives
Intra-operative monitoring
BP,HR,RR
ECG
SpO2ETCO2
FHR
Special situations - Trauma
Among the leading causes of maternal mortality/morbidity
Maternal life takes precedence over foetallife.
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
Indications for emergency Caesarean section in pregnant trauma patient: -1. Traumatic uterine rupture
2. Haemodynamically stable mother with foetal distess
3. Gravid uterus that is interfering with intraoperativesurgical repair
Special situations - Trauma
It is no longer considered to be a contraindication to laparoscopic surgery
Concerns in Laparoscopic surgeriesPneumoperitoneum with trendelenberg position
Reduced lung compliance and FRC.
Increased airway pressures
Hypoxia in advanced gestation.
Pneumoperitoneum with reverse trendelenberg position
Significant aorto venacaval compression
Reduced venous return & hypotension.
Pregnancy is a prothrombotic state.
Lower extremity venous stasis due to pneumoperitoneum- higher risk of thromboembolism
Special situations –
Laparoscopy
Recommendations for Laproscopy1. Use an open technique to enter the abdomen to
avoid potential uterine or fetal trauma.
2. Monitor maternal end-tidal CO2 (30–35 mmHg range) arterial blood gas (if the procedure is prolonged) to avoid fetal 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 uteroplacentalperfusion
5. Protect the uterus with lead shielding during intraopradiological procedures (Cholangiography)
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 feasible
Special situations –
Laparoscopy
Laparoscopic Vs Open
Appendicectomy A study was designed in USA (2007)
have shown that laparoscopic appendicectomy in pregnancy is associated with a low rate of intra-operative complication & less requirement of postoperative analgesia in all trimester. However, laparoscopic appendicectomy is associated with a significantly higher rate of fetal loss compared to open appendicectomy.
Open appendicectomy would appear to be the safer option for pregnant women for whom surgical intervention is indicated.
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.
Fetal 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.
Special situations - Neurosurgery
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 fetal oxygenation.
Osmotic diuresis can lead to fetal
dehydration.
Endovascular procedures abolish the need
for craniotomy. Fetal shielding during the
procedure is necessary
Special situations - Neurosurgery
Postoperative care:
Pregnancy is a hyper-coagulable state
& the risk of thromboembolic is further
increased by postoperative venous
stasis.
Early mobilization
Maintaining adequate hydration
Pneumatic stocking gloves
Pharmacological prophylaxis
Post op analgesia:
Adequate analgesia is important as pain will cause increased circulating catecholamines which impair uteroplacental perfusion.
Analgesia may mask the signs of early preterm labour.
Paracetamol & Diclofenac is pregnancy risk category B.
Ibuprofen, Morphine, Tramadol is pregnancy risk category C.
NSAIDS can cause early closure of ductus arteriosus in 3rd trimester.
OutcomeCohen, Kerem et all, American Journal of Surgery in 2005
conducted a literature review of 54 studies in England over
last 10 years
Statistics
Total patients reviewed – 12,452
Maternal deaths – 0.006%
Miscarriage – 5.8%
Elective termination of pregnancy – 1.3%
Preterm labor induced by surgery – 3.5%
Foetal loss – 2.5%
Prematurity – 8.2%
Major birth defects (1st trimester surgeries) – 3.9%
R. Cohen-Kerem et al. / The American Journal of Surgery 190
(2005) 467–473
OutcomeConclusions: - Using modern surgical and anesthetic techniques, the risk of
maternal death appears to be very low.
Surgery and general anesthesia do not appear to be major risk factors for spontaneous abortion.
The rate of elective termination appears to be in the rangeof the general population.
Non-obstetric surgical procedures do not increase the risk for major birth defects. Hence, urgent surgical procedures should be performed when needed.
Acute appendicitis, especially when accompanied by peritonitis, appears to be genuine risk for surgery induced labor or fetal loss.
R. Cohen-Kerem et al. / The American Journal of Surgery 190
(2005) 467–473
Conclusion:
Remembering the physiological & anatomical changes of
pregnancy.
Prevention of foetal asphyxia by maintaining maternal oxygenation, ventilation& haemodynamic stability.
Remembering postoperative thromboprophylaxis.
“ A baby is something you carry inside you for nine months, in your
arms for three years and in your heart till the day you die…”
-- Mary Mason