Resuscitation in pregnancy

Resuscitation in pregnancy

• Survival rate 6.9%

Physiological changes

• Uterine blood flow not autoregulated – directly proportional to MAP
• Aortocaval compression – Can reduce CO 10-30%
  • Supine hypotension syndrome after 30 minutes supine
  • Need left lateral tilt – Cardiff wedge provides 27 degrees tilt
• Avoid femoral or saphenous sites for IV access as abdominal vasculature compression can limit delivery of medications >20 weeks
• Minute ventilation increased by progesterone via tidal volume NOT respiratory rate so do NOT dismiss tachypnoea
• Diaphragm rises 4cm, thoracic cage 2cm wider
• Increased metabolic O2 consumption and rapid hypoxia
• Target SpO2 >95% to maintain PaO2 >70mmHg to optimise maternal oxygenation and placental O2 delivery

Physiology

• Foetal mechanisms
  • Physiological acidaemic state allows preferential oxygen transfer vs. mother
    • Also causes right shift of oxygen-dissociation curve to increase oxygen delivery to fetal tissues
  • Fetal cardiac output protects against brief hypoxia by increasing umbilical blood flow, placental gas exchange and redistribution to vital organs
• Increase fluid volumes delivered are increased 50% above that required by non-pregnant patient
• Volume MUST be adequately replaced before vasopressors are initiated as uterine arteries are maximally dilated and blood flow is pressure dependent

Vasopressors

• Vasopressor selection
  • Phenylephrine (Cat C)
    • Alpha-1 selective with no beta-activity. Crosses placenta but favourable fetal acid-base profile
  • Ephedrine (Cat C)
    • Mixed alpha and beta stimulation and can induce foetal acidosis
  • Noradrenaline, dopamine and vasopressin are all Cat C with limited data
  • Atropine cat B, dobutamine cat B
  • Amiodarone Cat D. Do not use due to risk of congenital goitre and hypothyroidism

Sepsis

• Septic shock is rare in pregnancy 
  • 0.002 to 0.01% of deliveries
  • 0.3-0.6% of pregnancies
• Pyelonephritis, pneumonia, chorioamnionitis and septic abortion are commonly seen
• Pyelonephritis
  • Progesterone dilates ureters, and mechanical compression can cause relative obstruction
  • Hospitalise all pregnant cases of pyelonephritis as higher risk of bacteraemia
• Pneumonia
  • Can be particularly severe as rapid decline in SpO2 with/without sepsis

Airway

• Airway oedema, weight gain, difficult mask ventilation, laryngoscopy and intubation
• Desaturation due to increased oxygen consumption and decreased FRC
• Mallampati Class II increases
• Capillary friability
• Avoid nasal intubation (fragile engorged mucosa)
• Difficult intubation 1-6% and failed intubation 0.1-0.6%
• Decreased lower oesophageal tone, increased intra-abdominal pressure, decreased gastric emptying and a full stomach all increase aspiration risk

Intubation

• Intubation
  • Smaller sized ET should be used
  • Short handled laryngoscopes
  • Video scopes facilitate first-pass success, direct visualisation and reduce risk of complications and hypoxia
  • Place patient in supine position and manually displace uterus to left
  • Sniffing position
  • Standard doses of RSI drugs
  • Avoid respiratory alkalosis as decreases uteroplacental flow

Causes of arrest

• Obstetric
  • Haemorrhage 17.2%
  • Severe pregnancy-induced HTN 15.7%
  • Amniotic fluid embolism
  • Idiopathic peripartum cardiomyopathy (8.3%)
  • Iatrogenic events
  • Failed intubation
  • Pulmonary aspiration
  • IV LA overdose
  • Drug error/allergy
  • Hypermagnesaemia
• PE 19.6% – Thrombus, air, fat
• Stroke 5%
• Trauma
• Infection or sepsis 12.6%
• Other – 19.2%

Resuscitation in pregnancy

• If fundal height at or below the umbilicus (<20 weeks) then resuscitative efforts should be no different to non-pregnant female
• If uterus palpable above umbilicus, need to manually displace uterus to left and make preparations for perimortem C-section
  • No evidence for improved haemodynamics or outcomes with aortocaval decompression but manual displacement is as good or better than lateral tilt
• Factors associated with improved fetal survival
  • Gestational age >28 weeks or fetal weight >1kg
  • Short interval between maternal death and delivery
  • Maternal death not due to chronic hypoxia
  • Healthy fetal status prior to maternal death
  • NICU
  • Quality of maternal resuscitation

Resuscitative hysterotomy

• If estimated >24 weeks (i.e. viable)
• Prognosis best if delivery within 5 minutes of maternal death (should still be performed if >5 minutes though)
• One case report of neurologically intact survival at 30 minutes so proceed
• Drain bladder if will not delay incision
• Splash abdomen with povidone-iodine. Do not drape (too slow)
• Vertical incision from just below umbilicus to symphysis pubis
• Use fingers to blunty separate rectus muscles
• Bluntly or with scalpel enter peritoneum
• Retract above and below
• Make vertical incision in midline of uterus and enter cavity bluntly with fingers and extend incision with scissors
• If anterior placenta identified, go through this as increased bleeding is a necessary complication

Resuscitative hysterotomy

• Rupture amniotic sac with sharp instrument if not occurred spontaneously and suction
• Place hand into uterine cavity between symphysis pubis and fetal vertex or buttocks (if breech)
• Elevate vertex or buttocks out of pelvis and then remove bladder retraction
• Once head or buttocks at level of incision, have assistant put pressure on fundus
• If breech, deliver buttocks, then both legs, then body to shoulders and when one arm is delivered, rotate and deliver contralateral arm, flex head and deliver baby
• If footlng breech do same but deliver feet first then arms as per breech
• Doubly clamp the cord, cut between clamps (do not delay – resuscitation is more important)
• Manually remove placenta and provide 10U IM oxytocin + uterine massage
• Clean out uterine cavity with sponges, pack with moistened laparostomy sponges and wait for surgeon

Last Updated on October 13, 2020 by Andrew Crofton