Critical Care in

Obstetrics:

An Innovative and Integrated Model for Learning the Essentials

Respiratory Distress Syndrome and Pulmonary Edema

Sonya S. Abdel-Razeq, MD

Maternal-Fetal Medicine Surgical Critical Care

Assistant Professor

Yale School of Medicine New Haven, CT

I have no conflicts of interest to disclose

Disclosure

§  Learning objectives

§  ARDS

§  Background

§  Diagnosis & Treatment

§  Pulmonary edema

§  Background

§  Diagnosis & Treatment

§  Summary

§  Evidence

Outline

§  Define Acute Respiratory Distress Syndrome (ARDS)

§  Identify causes of ARDS and pulmonary edema

§  Understand diagnostic evaluation and treatment options

Learning Objectives

ARDS: Background

Case Scenario

§  35yo G1P0 IVF twin gestation EGA 26w admitted for worsening PNA. Increasing O2 requirement despite appropriate culture guided antibiotic therapy. BMI 38 kg/m2.

§  What must you be suspicious of?

§  Drug resistant organism

§  Poor med compliance

§  Undiagnosed infection

§  ARDS

§  Berlin Definition (2012 task force):

§  Respiratory failure not explained by cardiac failure or fluid overload

§ Occurs within one week of known insult or new/ worsening respiratory symptoms

§  Unexplained bilateral opacities (CXR or CT)

§  Three severity categories based on PaO2/ FIO2 ratio

ARDS: Background

§ 60-day mortality rate: 22% § ARDS Network trials: NIH Heart, Lung and

Blood Institute

§  Responsible for up to 19% obstetric ICU admissions

ARDS: Background

§  Alveolar lung injury causes diffuse alveolar damage

§ Release of pro-inflammatory cytokines § Tumor necrosis factor (TNF), interleukin (IL)-1,

IL-6, IL-8

§ Neutrophil recruitment

§ Subsequent damage to capillary endothelium and alveolar epithelium

ARDS: Pathophysiology

§  Protein escapes from vascular space, then oncotic gradient is lost, then air spaces contain proteinaceous fluid and debris

§  Loss of surfactant

§  ARDS effects

§  Impairment of gas exchange

§ Decreased lung compliance

§  Increased pulmonary arterial pressure

ARDS: Pathophysiology

§  What was/were her risk factor(s)?

§ Multiple gestation

§ AMA

§ Pneumonia

§  IVF

§ Obesity

§  More than 60 attributable causes identified

§  Sepsis most common etiology

§  Aspiration §  One-third of hospitalized that have aspirated

§  Pneumonia §  Community-acquired pneumonia most common cause

outside of hospital

§  Massive transfusion, >15 units red cells

§  Transfusion-related acute lung injury

§  Severe trauma

§  Other: obesity, pancreatitis, contrast, drugs

ARDS: Causes

§  Unique to pregnancy §  Preeclampsia/ eclampsia

§  Tocolytic-induced pulmonary edema

§  Chorioamnionitis

§  Amniotic fluid embolism

§  Placental abruption

§ Obstetric hemorrhage and resuscitation

§  Endometritis

§  Retained products of conception

§  Septic abortion

ARDS: Causes

ARDS: Stages

§  Exudative stage §  Day 1 to day 7-10

§  Alveolar damage

http://commons.wikimedia.org/wiki/File:ARDS.jpg http://www.medindia.net/patients/patientinfo/respiratory-distress-syndrome.htm

§  Proliferative phase §  Resolution of pulmonary edema

§  Proliferation of type II alveolar cells

§  Fibrotic stage § Obliteration of normal lung architecture

§  Diffuse fibrosis

§  Cyst formation

ARDS: Stages

ARDS: Diagnosis & Treatment

§  Hypoxemia appears within 6 to 72 hours of inciting event

§  Dyspnea, cyanosis, and diffuse crackles

§  Rapid progression

§  Diagnosis §  ARDS versus cardiogenic pulmonary edema

§ Physical exam

§ Brain natriuretic peptide (BNP), < 100 pg/mL

§ Echocardiogram may be helpful

ARDS: Diagnosis

ARDS §  Chest X-ray

§  35yo G1P0 IVF twin gestation EGA 26w admitted for worsening PNA. Increasing O2 requirement despite appropriate culture guided antibiotic therapy. BMI 38 kg/m2. Nonproductive cough.

§  T 99F HR 120 RR 32 BP 110/60 90% (4L)

§  What is your next intervention?

§  Broaden antibiotic coverage and wait for response

§  Oxygen supplementation via nonrebreather facemask

§  Rapid Response Team activation

§  Transfer to ICU and intubate

§  Supplemental oxygen § High flow oxygen, 70% via facemask

§ ARDS usually requires higher concentration

§ Mechanical ventilation

ARDS: Treatment

§  Mechanical Ventilation

§ Low tidal volume ventilation §  VT 4 to 6 mL/kg predicted body weight (PBW)

§  Plateau pressure < 30 cmH2O

§  RR titrated to maintain pH

§  Appropriate fraction of inspired (FIO2) and positive end-expiratory pressure (PEEP)

§ No published studies in pregnant women

§ Pre-ARDSnet data suggesting more barotrauma with higher VT

ARDS: Treatment

§  She is now in the ICU. Her mental status has declined and she is unable to protect her airway. Intubation occurs without difficulty. The RT asks for vent parameters.

§  The intensivist, nurse, and RT all look over at you…

§  What parameters will you need to specify?

§  Mode of ventilation

§  Respiratory rate

§  FIO2

§  PEEP

§  All of the above

§  Respiratory changes in pregnancy § 20% increase in O2 consumption

§ 15% increase in metabolic rate

§ VE increases, RR stable

§ VT increase by 40% over baseline

§ ABG: respiratory alkalosis compensated by metabolic acidosis § Stable pH

§ PaCO2: 28 to 32 mmHg

Key Points: Gravid Patient

§  Minute Ventilation (VE)

§ Amount of gas that moves in or out of lung in one minute

§ VT x rate = VE

§  Tidal Volume (VT)

§ Amount of gas that moves in or out of lung in one breath

Helpful Definitions

§  Indicated with inability to maintain airway or adequate oxygenation or ventilation

§  Respiratory rate (RR) > 30/min

§  Inability to maintain arterial O2 saturation > 90% with FIO2 > 0.60

§  PCO2 > 50 mmHg with pH < 7.25

Endotracheal Intubation

§ Ventilator Settings § VE adjusted to maintain PaCO2 30 to 32

mmHg

§ pH 7.40 to 7.47

§ PaCO2 < 30 mmHg may decrease uterine blood flow due to significant respiratory alkalosis

Goals

§ Gravid Patient

§ Permissive hypercapnia § Does not appear to adversely affect fetus

(CO2 level 60 mmHg)

§ Positive End-Expiratory Pressure (PEEP) § Added to mitigate end-expiratory

alveolar collapse, usually 5 cm H2O

§ Higher levels may be required in third-trimester

Other Considerations

§ Most medications for analgesia, sedation, paralysis reach fetal circulation

§ Analgesia § Opioids acceptable, avoid NSAIDs

Other Considerations

§  Permissive hypercapnia (PaCO2 >60 mmHg)

§ Results from lower VT and minute ventilation

§ Causes vasodilation, tachycardia, hypotension

§ Does not appear to adversely affect fetus

§  Increases uterine vascular resistance

§  No human data regarding permissive hypercapnia in pregnancy

ARDS: Treatment

§  She is now intubated and respiratory status critical but stable. What other interventions are indicated at this time?

§  Bicarbonate therapy

§  PEEP of 2 cm H2O

§  Prone positioning

§  Fluid conservative management

§  Corticosteroids

§  Bicarbonate solution §  Advocated by some to correct acidosis

§  Placental transfer not well studied

§  Positive End-Expiratory Pressure (PEEP) § Mitigate end-expiratory alveolar collapse,

usually 5 cm H2O

§ May need higher levels in third-trimester

§  Increased intra-thoracic pressure and decreased venous return

ARDS: Treatment

§  Prone positioning

§ Data supports this in refractory hypoxemia to improve oxygenation

§ Not shown to improve overall mortality

§ In pregnancy, meticulous positioning and fetal monitoring required

ARDS: Treatment

§  Appropriate treatment of precipitating event

§  Fluid and hemodynamic management

§  Lowest intravascular volume to maintain adequate tissue perfusion

§  Urine output, acid-base status, CVP monitoring

§  Vasopressors/ inotropes as needed

§  Nutrition

§  Enteral route preferred

§  Corticosteroids

§  Controversial benefit

ARDS: Treatment

§  Best judgement

Fetal Monitoring

Pulmonary Edema

§  Occurs in 0.08% of normal pregnancies

§  Occurs in 3.4% of preeclamptic pregnancies

§  Occurs in 5% preterm labor situations

§  In all affected pregnancies

§ Tocolytic therapy or cardiac disease: 50%

§ Preeclampsia (PEC) or iatrogenic volume overload: 50%

Pulmonary Edema: Background

CATEGORY SPECIFIC RISK FACTORS

Prepregnancy conditions Cardiovascular diseases Obesity Increased maternal age Endocrine disorders

Pregnancy-specific diseases PEC Cardiomyopathy Sepsis Preterm labor Amniotic fluid embolism Pulmonary embolism

Pharmacological agents Beta-agonists Corticosteroids Magnesium sulfate Illicit drugs

Iatrogenic volume overload

Fetal conditions Multiple gestation

Pulmonary Edema: Risk Factors

§ Clinical presentation

§ Tachypnea

§ Dyspnea

§ Hypoxemia

§ Tachycardia

§ Diffuse crackles

§ Imaging findings

Pulmonary Edema: Presentation

§  Tocolytic therapy

§  Beta-2 agonists

§  Calcium channel blockers

§ Magnesium sulfate

§  Contributing factors §  Multiple gestation, maternal infection

§  Simultaneous administration of multiple medications

§  Fluid overload

§  Cardiac dysfunction

§  Capillary permeability

Pulmonary Edema: Tocolytic Therapy

§ No definitive diagnostic tests

§ Diagnosis of exclusion in those receiving tocolytic therapy

Pulmonary Edema: Tocolytic Therapy

§  Treatment

§ Discontinuation of offending agent

§ Supplemental oxygen

§ Fluid restriction

§ Diuresis

§ Mechanical ventilation as necessary

Pulmonary Edema: Tocolytic Therapy

§ 23 per 1,000 deliveries during delivery

§ 11 per 1,000 deliveries during postpartum

§ Due to preexisting or new cardiac disease

Pulmonary Edema: Cardiogenic

§ Uncommon complication

§  Risk factors

§ Older

§ Multigravid

§ In presence of additional organ system dysfunction

Pulmonary Edema: Preeclampsia

§  Multifactorial Etiology §  Volume overload

§  Decreased plasma oncotic pressure

§  Increased capillary permeability

§  Increased pulmonary capillary hydrostatic pressure

Pulmonary Edema: Preeclampsia

Pulmonary Edema:

Diagnosis & Treatment

§  Physical exam

§  CXR

§  Blood studies §  Electrolytes, creatinine, protein

§  Urinalysis

§  Arterial blood gas (ABG)

Pulmonary Edema: Diagnosis

§  EKG

§  Echocardiogram §  Myocardial, valvular, structural pathologies

Pulmonary Edema: Diagnosis

§  40yo G1P0 EGA 34w admitted for superimposed PEC evaluation in the setting of new onset dyspnea, cough and office BP 152/90 mmHg. Bilateral crackles on PE.

§  P 115 BP RR 20

§  What is your next step?

§ Obtain CXR

§  Expanded history and exam

§  Administer furosemide 40 mg IV

§  Prepare for delivery in light of PEC

Pulmonary Edema

http://www.histopathology-india.net/PulEd.htm Image courtesy Sherif R. Zaki, MD, Ph.D. www.cdc.gov

Pulmonary Edema

§  Chest X-ray (CXR)

http://en.wikipedia.org/wiki/Image:Noncardiogenic_pulmonary_edema.JPG

§  CT Chest, coronal

§  Treatment

§ Discontinuation of offending agent

§ Treatment of underlying condition

§ Supplemental oxygen

§ Fluid restriction

§ Diuresis

§ Mechanical ventilation as necessary

Pulmonary Edema: Treatment

Summary

§  Respiratory failure in pregnancy is rare

§  ARDS is a type of respiratory failure, with acute onset of bilateral infiltrates and hypoxemia

§  ARDS causes impaired gas exchange, decreased compliance, increased pulmonary arterial pressure

§  More than 60 possible causes of ARDS have been identified

§  Mechanical ventilation with low VT strategy is standard management

Summary

§  Permissive hypercapnia and increased PEEP may be considered.

§  Pulmonary edema is most often secondary to tocolytic therapy, cardiac failure, severe preeclampsia, or eclampsia.

§  Treatment of respiratory failure involves treatment of the underlying cause, oxygenation/ ventilatory support, sedation, analgesia, volume management, hemodynamic support, nutritional support, DVT prophylaxis.

Summary

§  Acute respiratory failure requiring endotracheal intubation is notable for:

§  respiratory rate (RR) > 30/min

§  inability to maintain arterial O2 saturation > 90% with FIO2 > 0.60 (PaO2 <55 mmHg)

§  PaCO2 > 50 mmHg with pH < 7.25

Summary

§ Multiple modes of ventilation may be used in pregnancy

§ Ventilator goals for the gravid patient:

§ VE adjusted to maintain PaCO2 30 to 32 mmHg

§ pH 7.40 to 7.47

Summary

 Thank You for Your Attention!

Planning Committee  

 Mike Foley, Director Shad Deering, co-Director Helen Feltovich, co-Director Bill Goodnight, co-Director Loralei Thornburg, Content co-Chair Deirdre Lyell, Content co-Chair Suneet Chauhan, Testing Chair Mary d’Alton Daniel O’Keeffe Andrew Satin Barbara Shaw