anaesthesia for non obstetric surgery in pregnant patients presenter: dr. satya pal moderator: dr....

Anaesthesia for Non Anaesthesia for Non Obstetric Surgery in Obstetric Surgery in Pregnant PatientsPregnant Patients

Presenter: Dr. Satya PalModerator: Dr. Geetanjali

University College of Medical Sciences & GTB Hospital, Delhi

email: [email protected]

IncidenceIncidence0.3% to 2.2% of pregnant women undergo

surgeries

Annual incidence - 75,000 – 80,000 (USA)

Centralized data unavailable in India

Commonest surgery - Appendicectomy

IncidenceIncidence

Am J Obstet Gynecol 1989

Surgeries in pregnancySurgeries in pregnancy Pregnancy related

Cervical encirclageFetal surgeryOvarian Cystectomy

Not related to pregnancy

Appendicectomy, CholecystectomyTraumaMalignancies

How these patient are different from other surgical patients?

Two patients - mother - fetus

Physiological changes in mother

Why this topic is Why this topic is important?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

KEY AREASKEY 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

Altered maternal Altered maternal physiologyphysiologyRespiratory system: 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

Altered maternal Altered maternal physiologyphysiologyHematological changesHematological 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

Altered maternal Altered maternal physiology…physiology…Altered response to anaesthesiaAlveolar 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


during pregnancy





Special situations

FETAL EFFECTSFETAL EFFECTSTeratogenicityTeratogenicityAny 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)

FETAL EFFECTS…FETAL EFFECTS…Teratogenicity…Teratogenicity…Maximum sensitivity of organs for

development of structural 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

FETAL EFFECTS…FETAL EFFECTS…Documented teratogens: 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

FETAL EFFECTS…FETAL EFFECTS…Radiology: a threat?? 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)

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

Documented teratogenic Documented teratogenic drugsdrugs(Adapted: ACOG Educational Bulletin )(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

FETAL EFFECTS…FETAL EFFECTS…

Anaesthetic agents and teratogenicity

Teratogenic effects of anaesthetic agents are probably minimal to non-existent and have never been conclusively documented


Safe drugs: I/V induction agents Narcotics Neuromuscular blockers Inhalational agents Local anaesthetics

Drugs of concern:

Nitrous oxide,

BZD

FETAL EFFECTS…FETAL EFFECTS…Nitrous oxideNitrous oxideAnimal 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

FETAL EFFECTS…FETAL EFFECTS…Nitrous oxide…Nitrous oxide…Human studies No proved teratogenicity

Significant exposure for prolonged duration results in altered enzyme activity

No teratogenic effects in clinically administered dose.

FETAL EFFECTS…FETAL EFFECTS…BENZODIAZEPINES (BZD)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


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

FETAL EFFECTS…FETAL EFFECTS…BEHAVIORAL TERATOLOGYBEHAVIORAL 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


“There are not adequate data to extrapolate the animal finding to humans”

(Anesthetic & Life Support Drug advisory Committee of US FDA)

Fetal effects…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


during pregnancy





Special situations

Uteroplacental perfusion Uteroplacental perfusion and fetal oxygentationand 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

Uteroplacental perfusion Uteroplacental perfusion and fetal oxygentation…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

Uteroplacental perfusion Uteroplacental perfusion and fetal oxygentation…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.

Factors affecting the Factors affecting the Uteroplacental perfusionUteroplacental 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


during pregnancy





Special situations

PRACTICAL CONSIDERATIONSPRACTICAL CONSIDERATIONS

Timing of surgeryFetal monitoringFull stomach precautionsLeft uterine displacementAnaesthetic considerationsTocolytic agents

PRACTICAL CONCERNS…PRACTICAL CONCERNS…

When to do the surgery??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


When to do the surgery??When to do the surgery??

Carvalho B, Anesth Analg Suppl IARS


Fetal monitoringFetal 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 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 and interpret the tracing

FHR variability Good indicator of fetal well being after 25-27 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.


Anaesthetic considerations in1st Trimester

Maternal ↑ oxygen requirementModified drug pharmacokineticsCareful airway manipulation

FetalRisk of teratogenicity Impaired UBF

PRACTICAL CONCERNS…PRACTICAL CONCERNS…Anaesthetic considerations in 2nd and

3rd trimester

Maternal

Prone to hypoxiaAspiration prophylaxisPreparation for difficult airway Increased risk of thromboembolic

complicationsAvoid hyperventilation

PRACTICAL CONCERNS...PRACTICAL CONCERNS...Fetal 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

PRACTICAL CONCERNS….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

PRACTICAL CONCERNS…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

PRACTICAL CONCERNS…PRACTICAL CONCERNS…Tocolytic agentsTocolytic 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


during pregnancy





Special situations

Counselling and Counselling and reassurancereassurance 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

ANAESTHETIC MANAGEMENT

Pre-anaesthetic Pre-anaesthetic preparation..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

ANAESTHETIC MANAGEMENT… ANAESTHETIC MANAGEMENT… Choice of AnaesthesiaChoice 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

AIM : To maintain oxygenation, normotension, eucapnia

and euglycemia

ANAESTHETIC MANAGEMENT… ANAESTHETIC MANAGEMENT…

MonitoringMonitoringMaternal 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)

ANAESTHETIC ANAESTHETIC

MANAGEMENT… 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

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

ANAESTHETIC MANAGEMENT..… 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

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


Postoperative managementPostoperative 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


Postoperative Pain Postoperative Pain managementmanagement Painincreased endogenous catecholamines

uterine vasoconstrictiondecreased UBFintrauterine 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


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

Recommendations…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.


during pregnancy





Special situations

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 – Special situation – LaparoscopyLaparoscopy

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



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

Special situation – Fetal Special situation – Fetal surgerysurgery

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

Special situation – Fetal Special situation – Fetal surgery….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 – Special situation – Electroconvulsive Shock Electroconvulsive Shock TherapyTherapy 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

Special situation – Special situation – Neurosurgery (e.g., Neurosurgery (e.g., Aneurysm, AV Aneurysm, AV malformation)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

Special situation – Trauma Special situation – Trauma during pregnancyduring 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

Special situation – Trauma Special situation – Trauma during pregnancy…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

ReferencesReferences

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

Thank You

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anaesthesia for non obstetric surgery in pregnant patients presenter: dr. satya pal moderator: dr....

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