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  • Nathan Riley, MD

Obgyno Wino Podcast Episode 18 - Critical Care in Pregnancy

"English, which can express the thoughts of Hamlet and the tragedy of Lear, had no words for the shiver and the headache...let a sufferer try to describe a pain in his head to a doctor and language at once runs dry." - Virginia Woolf, 'On Being Ill'

E-6 Spanish Red from Locations Wine

PB#211 - Published April 2019

Five Pearls

  1. Asking for help is not a sign of weakness

  2. In sepsis, fever may be absent, cultures may be negative, and a source may not be readily identified

  3. Optimization of maternal status will optimize fetal status

  4. Keep in mind the normal physiologic changes seen in pregnancy; a normal ABG in a non-pregnant patient may indicate impending respiratory failure in the pregnant patient

  5. Risks of preterm delivery must be weighed against the risks of continuing the pregnancy in the setting of critical illness


Let's start with some stats

- 1-10 obstetrics patients per 1,000 deliveries are admitted to the ICU

- majority postpartum

- usually for intensive monitoring

- usually short duration (1-2 days)

- maternal death rate after ICU admission varies greatly between high- and low-income countries (3.3% median versus 14%, respectively)

- demand for ICU admission is often driven by factors other than medical need, such as bed availability, staffing, or hospital culture, thus admission alone is not helpful in assessing maternal morbidity across hospitals (don't be fooled by the data!)

When to get an ICU consult for your OB patient?

- when in doubt, err on the side of ICU consult; encourage your colleagues to consult if they ever have a doubt!

- in the ICU, you'll find a better nurse to patient ratio, so more attention to your patient, as well as specialized monitoring equipment and training to nurses

- not every consult will result in ICU admission; you may even just get a second set of eyeballs and specialized recommendations from an intensivist

- general scenarios in which consult might be considered: clinically unstable (hypotension, hypoxemia) or high risk for deterioration (increased work of breathing)

- there's also the Sepsis in Obstetrics Score that you might consider utilizing, but validation studies only looked at pregnant women in the emergency department of one institution

- your clinical judgment supersedes all scoring systems

- Your biggest fear? The ICU team evaluates your patient and tells you to take a chill pill

- The actually worst case scenario? You don't call the ICU, then your patient crunk and dies


Pearl: Asking for help is unfortunately not rewarded in medical training, but you need to get over this if you want to be considered a competent physician, colleague and patient ally.

Common causes of maternal ICU admission

- hemorrhage and hypertensive disorders are the most common (covered in other practice bulletins; I have covered HTN in pregnancy in prior episodes 5, 6, 16, and 17)

- other common scenarios prompting ICU admission: sepsis and acute respiratory distress syndrome (ARDS)

Sepsis

- the terms systemic inflammatory response syndrome (SIRS) and severe sepsis have been abandoned

- now we use: infection, sepsis, and septic shock

- sepsis: infection + end organ damage

- septic shock: patient requires vasopressor support to maintain MAP of >65 mmHg and a serum lactate level >2 mmol/L after adequate fluid resuscitation

- how do you assess for end organ damage? unfortunately there isn't a slam dunk test

- the Quick Sequential Organ Failure Assessment has been proposed as a screen for sepsis, but it has not been validated in pregnancy and doesn't take into account the normal physiologic changes seen in pregnancy/postpartum

- in non- pregnant women, any two of the following are considered a positive screen and need for further assessment: systolic BP 100 mmHg or less, RR 22 breaths/min or more, or altered mental status

- rapid initiation of treatment for sepsis is important: early antibiotics and fluid resuscitation

Pearl: in sepsis, fever may be absent, cultures may be negative, and a source may not be readily identified

ARDS

- nonspecific response of the lung to an insult: inflammation, increased fluids within the lung tissue due to increased vascular permeability, and loss of aerated lung units

- lung compliance drops, significantly increasing effort required to moved air leading to profound hypoxemia

- pregnant women are at increased risk! also more likely to require mechanical ventilation compared to non-pregnant women

- can be seen as a complication of preeclampsia and amniotic fluid embolism (AFE)

Recall: Mortality of AFE is as high as 85%. May present as acute dyspnea/respiratory failure, cardiovascular collapse, seizures, and/or DIC, commonly during obstetric procedures or evacuation of the uterus after fetal demise. Management: secure airway, IV hydrate, and bleeding. Collect ABG, CBC, coags, and fibrinogen. Call the ICU if you suspect AFE!

- in the past, mortality rates as high as 40%, though more recent data out of Canada suggests that it's now closer to 3%. Incidence is largely unclear, but likely much less than 1 in 1000 delivery hospitalizations. In a U.S. study, ARDS was identified in 33% of maternal deaths

- Diagnosis: onset of respiratory failure within 1 week of a clinical event in association with bilateral opacities on chest imaging and no other identifiable cause such as cardiac failure or fluid overload

Transport considerations for mom and fetus To another hospital

- stabilize mom before transport to another; if stabilization is impossible or delivery is imminent, then it's OK to wait until postpartum to transfer

- continuous cardiac rhythm and pulse oximetry monitoring

- establish venous access before transport

- if high probability of requiring intubation and mechanical ventilation during transport, secure an airway prior to departure

- transport should not be delayed by the inability to monitor fetus

Pearl: optimization of maternal status will optimize fetal status

Within hospital

- assess vitals during transport, have a defibrillator on-board as well as airway management equipment and supplemental O2 (crash cart); plus 2 staff members at least!

- individualize fetal monitoring: are you prepared to intervene in the hallway if you detect a fetal heart rate deceleration?!

- requesting an ICU bed ahead of is always helpful when you foresee complications (e.g. planned c-hyst for placenta accreta)

Ok...your patient is in the ICU. Now what?

- round on the patient daily; You are the expert on vaginal or surgical site bleeding, obstetric sources of infection, management of preeclampsia or eclampsia prophylaxis, and lactation --> share your expertise w/ the primary team!

- have a plan in place with all invested parties for plan for delivery in the event of acute deterioration

- if the patient is still pregnant, this will require a conversation with the patient about the risks/benefits of continuing the pregnancy as well as risks/benefits of early delivery of a preterm fetus

- if the patient is postpartum, every effort should be made to unite the patient with her baby when possible

Special considerations for managing critically ill pregnant women

- once mom is stable (1st priority!!!), determine gestational age of fetus, as this will likely affect the plan of care (example: if fetus is term, deliver! if preterm, risks/benefits of prematurity to fetus must be weighed against the risk of continuing pregnancy to the mom

- drug choice should be guided by potential adverse effects if the drug is known to cross the placenta and thus cause fetal malformation or alter placental perfusion (e.g. ↑HR, ↓BP from beta agonists; vasodilation due to negative inotropic effect of magnesium sulfate)

- risk to fetus to ionizing radiation and potentially teratogenic, albeit life-saving medications must be weighed against benefit of therapies to mom


Fun fact: A millisievert (mSv) is defined as "the average accumulated background radiation dose to an individual for 1 year, exclusive of radon, in the United States." 1 mSv is the dose produced by exposure to 1 milligray (mGy) of radiation. A chest x-ray exposes you to ~0.02 mGy. Abdominal CT exposes you to 8 mGy.


From CO#723: "Guidelines for Diagnostic Imaging During Pregnancy and Lactation"

From CO#723: "Guidelines for Diagnostic Imaging During Pregnancy and Lactation"

From CO#723: "Guidelines for Diagnostic Imaging During Pregnancy and Lactation"

- consider corticosteroids to promote lung maturation in pregnant women admitted to the ICU between 24w0d - 34wga and as early as 23w0d gestation, depending on a patient's or family's preferences regarding neonatal resuscitation; be judicious: only administer if, delivery is likely within the next 7 days

- steroids may cause hyperglycemia, hypokalemia, leukocytosis, and impaired wound healing, thus risks may outweigh benefits in critical maternal illness

- changes in fetal heart rate tracing may indicate sub-optimal maternal status and thus may reflect other end-organ damage

- if changes are noted, evaluate maternal VS, oxygenation and ventilation, acid-base balance, and cardiac output

- correction of these factors may result in improvement of the tracing without necessitating delivery

- if fetal monitoring is pursued with the knowledge that the patient is not stable for operative delivery, then "a clear plan must be made with the patient's family with the understanding that delivery is not safe regardless of deterioration of the fetal heart rate tracing"


Considerations for the laboring patient who requires critical care

- multi-disciplinary approach (obstetrics team, ICU team, anesthesiology, NICU staff, etc.)

- pre-viable: unlikely that L&D unit will be safest option

- advanced gestational age: L&D unit may be reasonable if adequate maternal support, monitors, and medications are readily available

- untreated pain can lead to significant hemodynamic changes

- if regional anesthesia isn't possible due to coagulopathy, hemodynamic instability, or limitations to patient positioning, parenteral or inhalational analgesics should be considered

- c-sections in the ICU setting pose obvious challenges: space is limited, infectious organisms are rampant, and staff aren't familiar with the procedure

- c-section in the ICU should be restricted to the rare occasion in which transport to an OR is not possible or peri-mortem


The fun stuff: physiology!

- physiologic changes in pregnancy abound:




Mechanical ventilation

- increased oxygen consumption, minute ventilation, and decreased functional residual capacity mean you have to act fast if ventilation is required

- remember how a ventilator works: a machine provides breaths through positive pressure; breaths are either triggered by the patient or by elapsed time after the last breath; gas will flow until a set volume or pressure is reached

- low-tidal-volume ventilation is now preferred over mechanical ventilation

- mechanical ventilation can still be life-saving, but both high oxygen concentrations and physical effects of positive pressure ventilation can damage the lungs

- low-tidal-volume ventilation aims to limit inflation pressures rather than chasing arterial blood gases (associated with lower mortality in non-pregnant women...obviously not enough data to make same assessment in pregnant women)


Hemodynamic monitoring

- central venous lines may be helpful for medication administration and in monitoring central venous pressure, which corresponds to left ventricular end-diastolic volume; subclavian or internal jugular access is preferred over femoral in the pregnant patient

- arterial cannulation is indicated if instantaneous BP monitoring is required, as in shock or with vasoactive medications, or when frequent ABGs are needed; radial access is preferred over femoral in the pregnant patient

- pulmonary artery catheter (Swan-Ganz) has been abandoned for peripheral lines


How to code a pregnant woman

- displace the uterus to the left to avoid aortocaval compression while perform chest compressions

- if initial resuscitative efforts fail, hysterotomy (i.e. perimortem cesarean delivery) may help, esp if the uterus is >20 wga, by alleviating aortocaval compression and restoring cardiac output

- it may also improve likelihood of fetal survival

- all that you need is a scalpel, homie

- go for it if 4-5 minutes of CPR haven't been adequate

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