anaesthesia for non obstetric surgery in pregnancy

8/10/2019 Anaesthesia for Non Obstetric Surgery in Pregnancy

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Anaesthesia for Non Obstetric

Surgery in Pregnancy

Presenter: Dr. Vaibhav Jain

Moderator: Dr. Aruna Chandak


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Incidence

0.3% to 2.2% of pregnant women undergosurgeries

Annual incidence - 75,00080,000 (USA)

Centralized data unavailable in India

Commonest surgery - Appendicectomy


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Incidence

Am J Obstet Gynecol 1989


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Surgeries in pregnancy

Pregnancy related

Cervical encirclage

Fetal surgery

Ovarian Cystectomy

Not related to pregnancy

Appendicectomy, Cholecystectomy

Trauma

Malignancies


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How these patient are dif ferent from other

surg ical pat ients?

Two patients - mother

- fetus

Physiological changes in mother


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Why this topic is important?

Must ensure safe anaesthesia for both mother andchild

Standard anaesthetic procedure may have to be

modified to accomodate both maternalphysiological 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


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KEY AREAS

Normal alterations in maternal phys io logy du r ingpregnancy

The potential fetal effectsfrom anaesthesia andsurgery

Maintenance of uteroplacental perfusion and fetaloxygenat ion

Pract ical consid erat ions

Importance of maternal counselling and reassurance

Special situat ions


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Altered maternal physiologyRespiratory system: O2 consumption & FRC rapid desaturation or

hypoxemia

Alveolar ventilation chronic respiratory alkalosis & bicarbonate and base buffer

mucosal vascularity & weight gain difficult maskventilation or intubation

Cardiovascular system:

Supine hypotension syndromeuteroplacentalperfusion

Distention of epidural venous plexus likelihood ofintravascular injection and enhanced spread of LA


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Altered maternal physiologyHematological changes Blood volume with lesser increase in RBCs volume

dilutional anemia

Factor I, VII, VIII, X, XII & FDP Increased risk ofthromboembolic complications

Benign leukocytosisdifficult to differentiate frominfection

Gastrointestinal system changes

LES tone, distortion of gastropyloric anatomy & gastric pressure from gravid uterusrisk ofregurgitation and aspiration


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Altered maternal

physiologyAltered response to anaesthesia Alveolar hyperventilation, reduction of FRC and

reduction of MACrapid induction of generalanaesthesia

thiopental requirements

protein binding due to low albumin free

fraction of drugs

sensitivity to peripheral neural blockadeL.A.dose requirement


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KEY AREAS






Special situat ions


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FETAL EFFECTS

Teratogenicity

Any significant postnatal change in function or formin 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)


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FETAL EFFECTS

Teratogenicity

Maximum sensitivity of organs for development ofstructural abnormalities

Brain 18-36 days

Heart 18-40 days

Eyes 24-40 days

Limbs 24-36 days

Gonads 37-50 days

Organogenesis: complete at 13 weeks


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Critical Periods


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FETAL EFFECTSDocumented 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 andsevere hypoglycemia

Infection

CMV, Herpes virus, Parvo virus B-19, rubella virus,toxoplasmosis

Drugs


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FETAL EFFECTSRadiology: a threat??

Effects are dose related

Less than 50 mGy is safe

Absorbed fetal dose for all conventional radiographicimaging is less than 50 mGy

No single diagnostic procedure results in a radiation dosethat threatens the wel l-being of the developing embry o andfetus(American College of Radiology)


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Diagnostic ultrasonography:

Considered to be devoid of embryotoxic effects

Potential side effects Fetal hyperthermiawith 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


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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


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FETAL EFFECTS

Anaesthet ic agents and

teratogenici ty

Teratogenic effects of anaesthetic agents are

probably minimal to non-existent and have never

been conclusively documented


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FETAL EFFECTS

Safe drugs: I/V induction agents

Narcotics

Neuromuscular blockers

Inhalational agents Local anaesthetics

Drugs of concern:

Nitrous oxide,

BZD


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FETAL EFFECTS

Nitrous oxideAnimal studies

Weak teratogen in rodents

Interferes with function of methionine synthetase by oxidation ofvitamin B12

decreased THF

decreased DNA synthesis

Decreased uterine blood flow : prevented by addition ofhalogenated inhalational agents


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FETAL EFFECTS

Nitrous oxideHuman studies No proved teratogenicity

Significant exposure for prolonged duration results in altered

enzyme activity

No teratogenic effects in clinically administered dose.


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FETAL EFFECTSBENZODIAZEPINES (BZD)

Earlier retrospective studies:Association between maternal diazepam ingestion during

1sttrimester and infant with cleft lip and palate

Later prospective studies:

- No higher risk when used in 1st trimester

Long term maternal administrationfetal BZD dependence &

withdrawal

Peripartum administration

Fetal hypotonia, hypothermia, respiratory depression,

feeding difficulties


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FETAL EFFECTS

A single shot of short acting BDZ or Nitrous oxide in

clinically administered anaesthetic concentration isunlikely to have any teratogenic effects


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FETAL EFFECTSBEHAVIORAL TERATOLOGY

Behavioral abnormality in absence of anyobservable morphological changes

CNS is specifically sensitive during period of major

myelination which extends from 4th

IU month to 2nd

postnatal month

Animalsprenatal administration of systemic

drugs e.g., Barbiturates, meperidine,promethazine & halothanebehavioral changes

Humanimplication remains unknown


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FETAL EFFECTS

There are not adequate data to

extrapolate the animal finding tohumans

(Anesthetic & Life Support Drug advisory Committeeof US FDA)


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Fetal effects

To summarize, anaesthesia and surgery are associated withhigher 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


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KEY AREAS






Special situat ions


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Uteroplacental perfusion and

fetal oxygentation

Fetal oxygenation depends on maternal oxygen delivery and

uteroplacental perfusion

Most serious risk during nonobstetric surgery is Intrauterineasphyxia

Maintenance of fetal well being :

Maternal oxygenation

Maternal carbon dioxide tension

Uterine blood flow


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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


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fetal oxygentation

Maternal CO2: Fetal CO2correlates 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.


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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 uterinevasoconstriction or hypertonus

(eg. ketamine>2mg/kg, toxic doses of LA)

CatecholaminesPain, anxiety, light anaesthesia increased plasmacatecholaminesdecreased UBF


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KEY AREAS






Special situat ions


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PRACTICAL CONCERNS

When to do the surgery?? Depends on the balance between maternal and fetal risk and

urgency of the surgery

1sttrimesterOrganogenesis

Increased fetal risk for teratogenesis and abortion

3rdtrimesterPeak of physiological changes of pregnancy

Increased maternal risk

Increased risk of preterm labour

Thus 2ndtr imesteris considered to be a ideal time for non

emergency, essential surgeries


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PRACTICAL CONCERNS

When to do the surgery??

Carvalho B, Anesth Analg Suppl IARS


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PRACTICAL CONCERNS

Fetal monitoring Intermittent or continuous FHR monitoring should

be considered for major surgical procedureswhenever technically feasible:

Ease of monitoring

Type & site of surgery (difficult during abdominal surgery)

Gestational age (after 18-20 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 andinterpret the tracing


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FHR variability

Good indicator of fetal well being after 25-27 wks

Loss of beat to beat variability and decreased baselineFHR are commonAnaesthetic agent administration

Declerations suggests fetal hypoxemia

Causes of FHR declerations

Inadvertent maternalhypoxemia, or inadequate uterine perfusion evaluation of maternal position, B.P, oxygenation, acidbase status and inspection of surgical sites asretractors may impair uterine perfusion.


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PRACTICAL CONCERNS

Anaesthetic considerations in 2nd and 3rdtrimester

Maternal

Prone to hypoxia

Aspiration prophylaxis

Preparation for difficult airway Increased risk of thromboembolic complications

Avoid hyperventilation


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PRACTICAL CONCERNS...

Fetal Premature labour / IUGR

Intrauterine asphyxia

Surgery related

Disease related problem

Diagnostic difficulties

Prolonged exposure to anaesthetics

Surgical manipulationsfetal risk

Anatomic and surface landmarks unreliable


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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 involvingradiation

Anatomic and surface landmarks can be unreliable


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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 surgeryand tocolytic therapy to be instituted if required

Not recommended at or after 34 wks

Do not affect the outcome


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PRACTICAL CONCERNS

Tocolytic agentsDrugs Side effects

2 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


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Counselling and reassurance

Patient should bereassured about the safety of anaesthesiaand the lack of documented associated teratogenicity

Warnedabout the increased risk of 1sttrimester miscarriage

and premature delivery in later trimesters

Educatethe patient about the symptoms of premature labour

and reinforce the need of left uterine displacement

Documentation of details of the risk discussed should bemaintained in patients records


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ANAESTHETIC MANAGEMENT


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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. preparationdrugs, machine, difficult airway cart, suctionand monitors


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ANAESTHETIC MANAGEMENTChoice of Anaesthesia

Choice of Anaesthetic technique depends on- Patients 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 theother in fetal outcomes

Regional techniques may be preferable

Safe anaesthetic management is more important thanparticular agent or technique


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AIM :

To maintain oxygenation, normotension, eucapnia and

euglycemia



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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)


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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 ( 2MAC) with high conc. of oxygen (FiO2 = 0.5) isrecommended.

The use of nitrous oxide should be limited during extremelylong operations in first trimester by giving high conc of oxygen


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Opioids and induction agents decreases FHR variabilityto greater extent than volatile agents

Positive pressure ventilation may reduce UBF

Avoid hyperventilation

Patients on magnesium for tocolysisreduce dose ofNMBs

Reversal agent to be given slowly (increased release ofAchincreased uterine tone and preterm labour)

Extubation when fully awake after return of protectiveairway reflexes


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ANAESTHETIC MANAGEMENT..

Regional anaesthesia

Advantages:

Minimal fetal drug exposure

Avoidance of complications of general anaesthesia

If no sedative or narcotics are supplementednochange in FHR variations to confuse interpretation

Post operative analgesia


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Management of regional anaesthesia

Pre-op preparation and monitoring same as of Generalanaesthesia

Reduced LA requirement / LA Toxicity

Careful aspiration and test dose

Avoid hypotension i.e., adequate preloading, maintain leftuterine tilt, choice of vasopressor

Patients on magnesium are more prone to hypotension, oftenresistant to treatment with vasopressors



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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 postoperativeanalgesia may mask awareness of early contractions and delaytocolysis

Early mobilization or DVT prophylaxis if required



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Postoperative Pain management

Pain

increased endogenous catecholamines

uterinevasoconstrictiondecreased UBFintrauterine hypoxia

Techniques: Nerve blocks

Local infiltration

Opioids

NSAID

NSAIDS

1stand 2ndtrimester - safe

3rd trimester - risk of premature closure of DA,

Pulm HTN, delayed labour

NSAID can be us ed before 32 wks and

Acetam inophen is safe


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Recommendations approved by AmericanSociety of Anaesthesiologists (ASA) and

American College of Obstetricians and

Gynecologists (ACOG) 2011

No currently used anaesthetic agentshave been shown to

have any teratogenic effectsin humans when using

standard concentrations at any gestational age

Fetal heart rate monitoringmay assist in maternalpositioning and cardiorespiratory management, and may

influence a decision to deliver the fetus


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Recommendations

It is mandatory to obtain an obstetr ic con sul ta tionbeforeperforming any non obstetric surgery or any invasive

procedures

Apregnant womanshould neverbe denied indicated surgery,

regardless of trimester.

Elective surgeryshould bepostponed

If possible, non-urgent surgery should be performed in thesecond trimesterwhen preterm contractions and

spontaneous abortion are least likely.


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KEY AREAS






Special situat ions

Special situation


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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.

Special situation

Laparoscopy

Special situation


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Guidelines by Society of American Gastrointestinal

Endoscopic Surgeons (SAGES) 2008

Safe during any trimester of pregnancy

Obtain preoperative obstetrician consultation

Intermittent lower extremity pneumatic compressiondevices to prevent venous stasis

The fetal heart rate and uterine tone should be

monitored in both preoperative and postoperativeperiods

End tidal CO2 should be maintained

Special situation

Laparoscopy

Special situation


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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 labouris present

Special situation Fetal


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Special situationFetal

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 procedureNeuraxial

anaesthesia

Open intrauterine proceduresGeneral anaesthesia

Special situation Fetal


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Special situationFetal

surgery.

Important considerations

Consider anaesthetic requirement of fetus

including amnesia, analgesia and immobilty

Control of uterine tone is essential

More intensive intraop FHR monitoring

Special situation


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pElectroconvulsive Shock

Therapy Used to treat major depression and BPD during

pregnancy when rapid control of symptoms is needed

Advantage

Avoids potential teratogenicity from psychotropicmedications

Not a risk factor for premature labour, miscarriage orstillbirth

Anaesthetic management

Confirm the absence of uterine contractions usingtocodynamometry before and after ECT

Monitor FHR before and after ECT

Special situationNeurosurgery


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p g y(e.g., Aneurysm, AV

malformation) Hypotensive anaesthetic techniques ( 2530% reduction in

SBP or mean BP less than 70 mmHg) can cause decrease inUBF

Dose (less than 0.5 mg/kg/hr) and duration of Sodium

Nitroprusside should be limited

FHR monitoring should be performed continuously specially ifinduced hypotension or hyperventilation is planned so thatnecessary adjustments can be made if fetal distress occurs

Hypovolemia and very large doses of mannitol should beavoided as they cause fetal dehydration

Endovascular treatmentsuterine shielding during periods ofradiation

Special situation Trauma


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Special situationTrauma

during pregnancy

Trauma is the leading cause nonobstetric cause of morbidityand mortality

Primary management goals are similar to the care ofnonpregnant trauma cases

Avoidance of hypoxia, hypotension, acidosis and hypothermiaare important for the maintenance of UBF and fetal well being

More prone to develop pulmonary edema

In stable patients without ongoing blood lossConservativefluid management

CVP monitoring should be considered if renal insufficiency orfluid overload occurs

Special situation Trauma


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Special situationTrauma

during pregnancy

Primary aim should be optimization of the mother and theobstetric 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

References


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References

Obstetric Anaesthesia, Principles and Practice. David H

Chestnut, 5th

Ed

Millers anesthesia. Ronald D Miller. 7thed.

Wylie and Churchill Davidsons A Practice ofAnaesthesia 7thed.

Clinical Anesthesia; Barash, Cullen, Stoelting, 7thedition

Yao &ArtusiosAnesthesiology. 7thedition

Nonobstetric surgery during pregnancy, ACOG committeeopinion, No. 474, Feb 2011

Roisin Ni M, David A. Anesthesia on pregnant patients fornonobstetric surgery. Journal of clinical anesthesia (2006) 18,60-66


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Thank You

anaesthesia for non obstetric surgery in pregnancy

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