anaesthesia for non obstetric surgery in pregnant patients presenter: dr. satya pal moderator: dr....
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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
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
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
FETAL EFFECTS…FETAL EFFECTS…
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
FETAL EFFECTS…FETAL EFFECTS…
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
FETAL EFFECTS…FETAL EFFECTS…
“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
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
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
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
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
PRACTICAL CONCERNS…PRACTICAL CONCERNS…
When to do the surgery??When to do the surgery??
Carvalho B, Anesth Analg Suppl IARS
PRACTICAL CONCERNS…PRACTICAL CONCERNS…
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.
PRACTICAL CONCERNS…PRACTICAL CONCERNS…
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
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
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
ANAESTHETIC MANAGEMENT… ANAESTHETIC MANAGEMENT…
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
ANAESTHETIC MANAGEMENT… ANAESTHETIC MANAGEMENT…
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
ANAESTHETIC MANAGEMENT… 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
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.
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
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
Special situation – Special situation – LaparoscopyLaparoscopy
Special situation – Special situation – LaparoscopyLaparoscopy
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
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