Obstetrics Flashcards
Amniotic Fluid Embolism
Considerations
Clinical Features
Management
DDx (Obs/Non Obs/Anaesthetic)
Amniotic Fluid Embolism
Considerations
Life threatening condition with multi-system derangements:
CNS: seizures, coma
Cardiovascular: hypotension, cardiovascular collapse, biventricular failure
Respiratory: pulmonary edema, ARDS
Hematological: coagulopathy
Pregnancy considerations (difficult intubation, aspiration, ↓ time to desaturation, aortocaval compression, 2 patients)
Need for immediate cardiopulmonary resuscitation & correction of coagulopathy
Need for multidisciplinary management including the ICU
Clinical Features (tend to happen suddenly)
Premonitory symptoms (restlessness, agitation, numbness, tingling)
Hypotension, biphasic cardiovascular collapse:
First phase (initial 15-30 min): RV failure & acute pulmonary hypertension
Second phase: LV failure
Hypoxemia, respiratory failure
Coagulopathy
Seizures/coma
Management
Call for help, code blue
If cardiac arrest → follow ACLS guidelines with obstetrical modifications:
Supradiaphragmatic IV
Left uterine displacement
Chest compressions higher on sternum than usual
Early intubation
Prepare for peri-mortem cesarean section; if no ROSC within 4 minutes of resuscitation, aim for delivery within 5 minutes of resuscitation
Ventilate/oxygenate: intubate, 100% O2
Fluid resuscitate in increments, avoid fluid overload that may lead to pulmonary edema or RV over-distension
Support circulation with vasopressors initially, may need inotropes in 2nd phase:
Start with norepinephrine
Add inodilators if needed: dobutamine, milrinone
Establish invasive monitoring: arterial line, central venous access & CVP monitoring
Call for transesophageal echocardiography
Treat coagulopathy:
Initiate massive hemorrhage protocol
Correct INR/PTT & platelets
Ensure normothermia & normocalcemia
Fetus management:
Institute fetal monitoring
Deliver fetus if fetal distress or maternal cardiopulmonary arrest
Post resuscitation care in ICU
Differential Diagnosis
Obstetrical:
Placental abruption
Eclampsia
Uterine rupture or laceration
Uterine atony
Peripartum cardiomyopathy
Non-obstetrical:
Myocardial infarction
Pulmonary embolism
Sepsis
Anaphylaxis
Venous air embolism
Transfusion reaction
Anesthetic:
High neuraxial
Local anesthetic toxicity
Medication error
Antepartum Hemorrhage
Considerations
DDx
Conflicts
Antepartum Hemorrhage
Considerations
Emergency situation
Pregnancy considerations (difficult intubation, aspiration, ↓ time to desaturation, aortocaval compression, 2 patients)
Potential for maternal massive hemorrhage, hemodynamic instability & lethal triad (coagulopathy, acidosis, hypothermia)
Potential for fetal distress & need for FHR monitoring
Discussion with obstetrics to determine the extent & cause of hemorrhage & whether emergency cesarean is required
Management
Simultaneous diagnosis & management in collaboration with obstetrics
Monitors (maternal & fetal), O2, & start 2 large bore IVs
Obtain history, perform physical examination including airway exam & intravascular volume status
Resuscitate to goal end points including FHR stability
Gather resources, get help, have OR set up for emergency cesarean section & possible massive hemorrhage:
Rapid transfuser
Massive transfusion protocol
Blood conservation techniques (cell saver, tranexamic acid, avoid lethal triad)
If emergency cesarean, will likely need GA (provided airway is reassuring) & titrated induction with ketamine & succinylcholine
Differential Diagnosis for Antepartum Hemorrhage
Placenta previa (painless)
Placenta abruption (painful)
Uterine rupture (true emergency)
Vasa previa (lethal to fetus, ok for mom)
Other less serious causes
Conflicts
Full stomach (RSI) vs. hemodynamic instability & need for titrated induction
Difficult airway vs. STAT cesarean section
Considerations in the Breastfeeding Patient
Transfer of Medications into Breast Milk
Maintaining supply
Considerations in the Breastfeeding Patient
Transfer of Medications into Breast Milk
“Pump and Dump” postop is outdated and no longer recommended
All anesthetic/analgesic drugs transfer to breast milk
Passive diffusion most common
Highly lipid soluble, less protein-bound, low MW, or higher pKa drugs have greater penetration into breast milk
Relative infant dose (RID) reflects relative neonatal drug exposure via breast milk
RID <10% considered safe
Almost all anesthetic drugs have RID «10%
Drugs not recommended in breastfeeding mothers:
Codeine, Tramadol (metabolized by CYP2D6 - ↑ risk if “ultra-metabolizer” mother breastfeeds “slow metabolizer” neonate)
Meperidine, high-dose morphine (low dose ok)
See https://www.ncbi.nlm.nih.gov/books/NBK501922/ for more info on specific agents
Minimize opioids/sedatives
Multimodal analgesia, regional techniques when possible
Pain interferes with successful breastfeeding → treat appropriately
Monitor patient & infant for sedation, respiratory depression
Resume breastfeeding as soon as possible postop (when patient is awake, alert, and able to hold infant)
https://pubs.asahq.org/anesthesiology/article/127/4/A15/19790/Anesthesia-amp-Breastfeeding-More-Often-Than-Not
Maintaining Supply of Breast Milk
Surgical stress often causes ↓ supply
Maintenance of adequate hydration
No prolonged fasting, encourage carbohydrate-containing clear fluids until 2 hrs preop
IV fluids (+/- dextrose) while NPO
PONV prophylaxis (ex Ondansetron, Metoclopramide, TIVA)
If possible, avoid drugs which may ↓ supply
Antihistamines
Anticholinergics
Phenylephrine
Where possible, breastfeed or pump immediately pre- and post-op
Consider pumping (and dumping) during prolonged surgery to maintain breast milk production & ↓ engorgement, risk of clogged ducts, & mastitis
Breech Presentation
Considerations
Management
Breech Presentation
Considerations
↑ risk of maternal mortality, morbidity, & complications (infection, perineal trauma, hemorrhage)
↑ risk of fetal complications:
Preterm delivery
Birth trauma
Major congenital anomalies
Umbilical cord prolapse
Hyperextension of the head
Spinal cord injuries with deflexion
Arrest of after-coming head
Intrapartum asphyxia
Intrapartum fetal death
Considerations of external cephalic version if performed
Recommended mode of delivery is cesarean section but vaginal delivery can be attempted with term singleton with adequate pre-planning (Canadian guidelines 2009)
Pregnancy considerations (difficult intubation, aspiration, ↓ time to desaturation, aortocaval compression, 2 patients)
Management
Analgesia for labor:
Early epidural if possible
The patient MUST NOT PUSH IN 1st stage of labor → might push a lower extremity through her partially dilated cervix, which may result in fetal head entrapment
Anesthesia for vaginal breech delivery:
Delivery preferred in the OR should emergency cesarean be required → always be ready to convert to GA!
Epidural strongly recommended
Very high risk including:
Umbilical cord compression
Fetal head entrapment
Anesthesia for cesarean delivery:
Neuraxial or GA
Possible need for uterine relaxation, have nitroglycerin available
May require larger incision or a vertical incision
Fetal head entrapment:
Nitroglycerin IV 100-400mcg OR nitroglycerin SL 400-800mcg
Likely need STAT GA: RSI (propofol/succinylcholine) & start 2-3 MAC of volatile to relax uterus
Be ready to support hemodynamics, control hemorrhage
Cervical Cerclage
Considerations
Management
Cervical Cerclage
Considerations
Pregnancy considerations (difficult intubation, aspiration, ↓ time to desaturation, aortocaval compression, 2 patients)
Risk of membrane rupture and degree of cervical dilation may dictate mode of anesthesia
Potential need for uterine relaxation and avoidance of coughing, straining, position changes that provoke bulging and rupture of membranes
Considerations for fetus:
Risk of preterm labor and need for fetal monitoring, avoidance of contraindicated medications (NSAIDS) after 32 weeks
Management
Depends on degree of cervical dilation with standard options of spinal, epidural or GA for transvaginal cerclage
Pudendal nerve block often inadequate
If no cervical dilation:
Typically spinal (or epidural) anesthesia requiring a T10 to S4 block (cervix: T10-L1 & vagina / perineum: S2-4)
If cervical dilation present:
Goals: produce adequate analgesia, prevent increase in intrauterine/intraabdominal pressure
Type of anesthesia depends on presence of bulging membranes and need for uterine relaxation:
Spinal:
Risk of sitting position and lumbar spine flexion leading to bulging of membranes, rupture and subsequent fetal death
Consider placing spinal/epidural in lateral position
Dose: 7.5 mg isobaric bupivacaine with fentanyl 15 mcg; alternative is 40 mg lidocaine
Epidural:
Midlumbar, 2% lidocaine with 5 mcg/mL epinephrine (10-15 mL total volume) with 100 mcg fentanyl for T8 block
General:
Indicated if bulging membranes in order to facilitate uterine relaxation with volatile anesthetics
Risks: coughing, bucking, vomiting leading to rupture of membranes, avoidance of GA in second trimester in terms of anesthetic exposure to fetus & risk of preterm delivery as well as risks of GA to parturient
CAS monitors, aspiration prophylaxis, left uterine displacement, RSI, maintain normal CO2, 0.5-1 MAC volatile plus opioid, fetal monitoring, avoidance of NSAIDS (ductus closure)
Removal of cervical cerclage:
Removed at 37-38 weeks; earlier if rupture of membranes or if labor begins
McDonald cerclage suture removal requires no anesthesia
Shirodkar suture removal requires anesthesia due to suture epithelialization; options are spinal or epidural
Some highly epithelialized sutures may require cesarean section
If epidural catheter placed consider leaving it in as labor may ensue within a few hours
Dyspnea in Pregnancy
Considerations
DDx (Cardiac/Resp/Obs/Others)
Dyspnea in Pregnancy
Considerations
Distinguish physiological vs pathological dyspnea
Focused differential diagnosis for pathological dyspnea (cardiac vs. respiratory vs. pregnancy-specific)
Perform a thorough physical exam & order appropriate investigations (e.g. labs, ECG, echo, PFTs, V/Q scan)
Liaise with internal medicine/obstetrics to diagnose & treat the underlying cause
Need for intrapartum invasive monitoring & postpartum monitoring in ICU/high acuity unit
Pregnancy considerations (difficult intubation, aspiration, ↓ time to desaturation, aortocaval compression, 2 patients)
Pathological vs. Physiological Dyspnea
Differential Diagnosis
Cardiac:
Cardiomyopathy (dilated/hypertrophic/restrictive)
Valvular heart disease (AR, AS, MR, MS)
Pulmonary hypertension & RV failure
Cardiac ischemia
Congenital heart disease
Arrythmias/heart block
Pericardial (percarditis/tamponade)
Respiratory:
Infections
Restrictive: interstitial lung disease, cystic fibrosis, neuromuscular disease, scoliosis
Obstructive: asthma, COPD
Pneumothorax
Anaphylaxis (bronchospasm)
Pregnancy-specific:
Severe preeclampsia/eclampsia
Amniotic fluid embolism
Pulmonary embolism (more common post-partum)
Tocolytic induced pulmonary edema
Peripartum cardiomyopathy (last month of pregnancy or during first 5 months post-partum)
High neuraxial blockade
Others:
Anemia
Hypothyroidism
Hepatic dysfunction
External Cephalic Version
Considerations
External Cephalic Version
Considerations
Pregnancy considerations (difficult intubation, aspiration, ↓ time to desaturation, aortocaval compression, 2 patients)
Must have continuous FHR monitoring during procedure
Complications (although uncommon) associated with the procedure:
Transient & persistent FHR abnormalities
Vaginal bleeding
Placental abruption
Fetomaternal hemorrhage (+ Kleihauer-Betke test)
Potential need for STAT delivery (have personnel, equipment, OR available)
Mode of anaesthesia (controversial):
Have full discussion with obstetrician & patient
Some evidence that neuraxial may ↑ success rates
Options: no anesthetic, IV analgesia, neuraxial (low vs high dose)
Fetal Distress
Considerations
Intra-uterine Resuscitation
Patterns
Fetal Distress
Considerations
Emergency situation with little time to optimize
Considerations of pregnancy, full stomach, 2 patients
Need for intra-uterine resuscitation & possible need to expedite delivery
Differential diagnosis to consider:
Maternal shock: excessive epidural/total spinal, sepsis, hemorrhage, cardiomyopathy
Maternal Fever
Cord prolapse
Placental abruption
Uterine hypertonus
Intrathecal narcotics (avoid CSE in women whose fetuses have decels)
Pregnancy induced hypertension
Uterine rupture
Footling breech
Need discussion with obstetrics regarding urgency of the distress & need for STAT delivery, maternal safety is the guiding factor
Intra-uterine Resuscitation
Fluid bolus (1-2 L crystalloid)
Supplemental O2
Left uterine displacement
Tocolysis: Stop oxytocin, consider nitroglycerine (1-2 sprays sublingual or 50-400 mcg IV)
Vasopressors to maintain uteroplacental perfusion
Reassuring (CLASS I or NORMAL) FHR Pattern
A baseline fetal heart rate of 110 to 160 bpm
Absence of late or variable FHR decelerations
Moderate FHR variability (6 to 25 bpm)
Early decelerations & accelerations may be present or absent
Non-reassuring (Class III or ABNORMAL) FHR Pattern: WORRISOME!
Absent baseline FHR variability
Recurrent late decelerations
Recurrent variable decelerations
Bradycardia
Sinusoidal pattern
Indeterminate (Class II) FHR Patterns: WATCH & SEE
The fetus may not be acidotic; however, continuation or worsening of the clinical situation may result in fetal acidosis
Examples: tachycardia, minimal or marked variability, absent variability without recurrent decelerations, absence of accelerations without absent variability, recurrent late or variable decelerations without absent variability, & prolonged decelerations
Multiple Gestation
Considerations
Anaesthetic management
Multiple Gestation
Considerations
Considerations of pregnancy, full stomach, 3 patients
↑ Maternal complications:
↑ aorto-caval compression
↑ desaturation
PPROM
Preterm labor
Prolonged labor
Pre-eclampsia/eclampsia
Placental abruption
DIC
Operative delivery
Uterine atony
Antepartum & PPH
↑ Fetal complications:
Preterm delivery
Congenital anomalies
Polyhydramnios
Cord entanglement
Umbilical cord prolapse
IUGR
Twin-to-twin transfusion
Malpresentation
↑ mortality
Anesthetic Management
If trial of labor & vaginal delivery as per obstetrics (most obstetricians allow a trial of labor if both twins have vertex presentation):
Ensure very good epidural & 2 large bore IV’s
Ensure OR & personnel ready for stat GA at any time especially for delivery of twin B
Have nitroglycerine available: uterine relaxation may be required to facilitate internal version & breech extraction of twin B
If cesarean section (more common scenario):
Ensure 2 large bore IV’s & active cross match
Epidural, spinal, & GA all safe for cesarean section
Aortocaval compression & rapid desaturation are exaggerated in this population
Have nitroglycerine ready for uterine relaxation
Be prepared for post partum hemorrhage, need for resuscitation & uterotonics
Neonatal resuscitation team must be present
Non Obstetric Surgery in Pregnancy
Considerations
Goals & Conflicts
Non Obstetric Surgery in Pregnancy
Considerations
Pregnancy considerations (difficult intubation, aspiration, ↓ time to desaturation, aortocaval compression, 2 patients)
Maintenance of uteroplacental perfusion:
FHR monitoring when possible
Avoid hypoxemia, hypotension, acidosis
Risk of preterm labour:
Obstetrical consult with consideration of steroids for lung maturity & magnesium for brain protection
Surgical considerations of a gravid uterus
Anesthetic drug effects on fetus (FHR changes, teratogenicity)
Goals & Conflicts
Delay nonelective surgery to the second trimester if possible
Optimize & maintain normal maternal physiologic function
Optimize & maintain uteroplacental blood flow & oxygen delivery (guided by FHR monitoring)
Preparations for preterm labour:
Fetal lung maturity
Availability of NICU
Avoid teratogens
Avoid stimulating the myometrium (oxytocic effects) to prevent preterm labour
Use regional anesthesia if possible
Peripartum Cardiac Arrest
Considerations
DDx
Gestational Age & Viability
Peripartum Cardiac Arrest
Considerations
Two patients with efforts focused on maternal resuscitation
Pregnancy considerations (difficult intubation, aspiration, ↓ time to desaturation, aortocaval compression, 2 patients)
Need for modified ACLS techniques:
Supradiaphragmatic IV
Left uterine displacement
Chest compressions higher on sternum than usual
Early intubation
Prepare for peri-mortem cesarean section; if no ROSC within 4 minutes of resuscitation, aim for delivery within 5 minutes of resuscitation
Rapid diagnosis & treatment of underlying etiology:
BEAU-CHOPS, H’sT’s, MgSO4 toxicity, local anesthetic toxicity
Aggressive interventions for difficult resuscitation (cardiopulmonary bypass, hypothermia, internal cardiac massage)
Differential Diagnosis
BEAU-CHOPS + H’sT’s:
B leeding/DIC
E mbolism: coronary/pulmonary/AFE
A nesthetic complications (high spinal, aspiration, failed airway, local anesthetic toxicity)
U terine atony
C ardiac disease (MI/ischemia/aortic dissection/cardiomyopathy)
H ypertension/preeclampsia/eclampsia
O ther: differential diagnosis of standard ACLS guidelines (“H’sT’s”)
Hyper-/hypokalemia, hypothermia, hypovolemia, hydrogen ion (acidosis), hypoxia
Tension pneumothorax, tamponade (cardiac), thrombus (coronary, pulmonary), toxins
P lacenta abruptio/previa
S epsis
Gestational Age & Viability
Fetal viability begins at approximately 24-25 weeks
Estimate gestational age:
<20 weeks: urgent cesarean section need not be considered because a gravid uterus of this size is unlikely to significantly compromise cardiac output
20-23 weeks: consider cesarean section for maternal resuscitation NOT survival of infant
> 24 weeks: cesarean section within 5 minutes for maternal & fetal resuscitation
Peripartum Cardiomyopathy
Background
Anesthetic Considerations
Anesthetic Management
Peripartum Cardiomyopathy
Background
Definition: new heart failure that develops in the last month of pregnancy or in the first 5 months postpartum
Echocardiogram findings: global dilation & dysfunction, strict criteria for EF ≦ 45%
Anesthetic Considerations
High risk cardiac patient & a very high risk of maternal/fetal M&M
Management at a cardiac centre in a multidisciplinary team setting
Management of cardiac medications & possible anti-coagulation
Anesthetic Management
Detailed review of functional capacity, echocardiogram, cardiology consults, & medications
Epidural, spinal, & GA are acceptable if goals met
Neuraxial may be contraindicated if patient anticoagulated
Set up OR for vasopressors, inotropes
Manage in a tertiary cardiac centre with invasive monitoring (arterial line, ± CVP/PAC) + TEE capability
Post-op ICU
Physiological Considerations of Pregnancy
Anesthetic Considerations:
Airway
CVS
Haematological
Physiological Considerations of Pregnancy
Anesthetic Considerations
Airway
Potentially more difficult laryngoscopy & intubation due to increased tissue edema & friability
↑ Risk reflux & aspiration, especially after 20 weeks GA & even more during labor
Respiratory
↑ minute ventilation (50%), ↑ oxygen consumption (20%)
↓ functional residual capacity (20%), at risk of rapid desaturation
PaCO2 ~30
Cardiovascular
Supine hypotension can occur due to aorto-caval compression
↑ Cardiac output, reaching a 40–50% ↑ by the third trimester. The largest increase occurs immediately after delivery. HR ↑ by 15-25%
↓ Blood pressure due to ↓ in SVR
Hematological
Physiologic anemia of pregnancy due to disproportionate ↑ in plasma volume (45% at term) compared with erythrocyte volume (20% at term)
Platelets usually normal unless gestational thrombocytopenia or other platelet disorders
Placenta Previa
Background
Considerations
Placenta Previa
Background
Placenta previa
Definition : presence of placental tissue that extends over the internal cervical os
Estimated to affect 1/200 pregnancies.
Known placenta previa necessitates cesarean birth somewhere between 36 to 37+6 gestational age
Placenta accreta spectrum includes 3 sub-types. The most important risk factor for developing these is placenta previa after a prior cesarean delivery
Accreta: placenta adhered to myometrium without invasion through uterine muscle
Increta: invasion of myometrium
Percreta: invasion of uterine serosa and other structure
Considerations
Pregnancy considerations (difficult intubation, aspiration, quick desaturation, aortocaval compression, 2 patients)
Increased risk of antepartum hemorrhage and the need for resuscitation and possibly emergency delivery
Increased risk of intra-operative blood loss even without pre-operative bleeding due to injury by obstetrician to an anteriorly located placenta during uterine incision and low uterine tone of the lower uterine segment implantation site
Placental Abruption
Considerations
Management
Placental Abruption
Considerations
Emergency with high maternal & fetal morbidity/mortality
Pregnancy considerations (difficult intubation, aspiration, ↓ time to desaturation, aortocaval compression, 2 patients)
Need to determine severity of abruption, amount of hemorrhage & degree of maternal/fetal compromise
Comorbidities associated with abruption:
Hypertension, pregnancy-induced hypertension, smoking, cocaine, EtOH, advanced maternal age, multiparity, multiple gestation, trauma, premature rupture of membranes, polyhydramnios
Mobilization of resources & personnel:
Multidisciplinary (2nd Anesthesiologist/anesthetic assistant, obstetrician, pediatrician, hematology/blood bank, ICU)
Resources (rapid infusers, blood products/massive transfusion protocol, uterotonics/tocolytics, invasive monitoring, tranexamic acid, cell salvage, rFVIIa)
Management
Urgency of delivery depends on severity of abruption
Establish large bore IV access, draw blood work, ensure close maternal & fetal monitoring, cross match & prepare for massive hemorrhage
Labor & vaginal delivery with epidural is safe for partial abruption without significant hypovolemia or coagulopathy
Urgent cesarean for more significant abruption with maternal or fetal compromise:
GA with RSI (ketamine & succinylcholine) if hemodynamic compromise
Aggressive volume resuscitation
Invasive monitors
Control & treat hemorrhage:
Massive transfusion protocol, rapid infuser, avoid acidosis/hypothermia/coagulopathy
Use of uterotonics
Blood conservation techniques: tranexamic acid, cell saver, rFVIIa, surgical technique
