Pulmonary causes of Peripartum Hypoxia

By/ Islam Ezz Eldin OsmanAssistant lecturer of Anesthesia, intensive care and pain management

Ain Shams University, 2016

Introduction

The respiratory system undergoes a number of anatomic and physiologic changes during

the course of a normal pregnancy.

Some of these changes predispose to development of several acute pulmonary

disorders.

Pregnancy can also affect the course of some chronic pulmonary diseases, most notably,

asthma and sarcoidosis.

Chronic causes

• Pneumonia• Bronchial asthma• Tuberculosis• Interstitial lung

disease(Sarcoidosis, Cystic fibrosis,…etc)

Acute causes

• Venous thromboembolism

• Aspiration Pneumonia• Amniotic fluid embolism• ARDS• Pulmonary edema• Anesthetic

complications causing hypoxia

• Pneumothorax

Pulmonary causes of Peripartum Hypoxia

Pneumonia• Although infrequent, it is the most common non-

obstetric infection to cause complications as well as maternal and fetal mortality in the peripartum period.

• The most common bacterial pathogens include Pneumococcus and H.influenzae.

Diagnosis

History taking Clinical signs and examination

Investigations (CBC, culture results, …etc).

Pneumonia

Antibiotics (penicillins and cephalosporins are usually preferred)

Hospitalization , administration of IV antibiotics, oxygen therapy

In severe cases ICU admission and possible need for mechanical ventilation.

Management

Bronchial Asthma

Some studies suggest that poor

asthma control may have an

adverse effect on pregnancy

decreased birth weight

Preterm Birth

increased rates of neonatal and maternal mortality

Although the mechanisms for these findings are still unclear, maternal hypoxia and alkalosis may play a role.

Bronchial Asthma

Diagnosis

History or presence of

typical symptoms

Wheezes

Chest tightness

Cough

Dyspnea

Reversible airway obstruction on

spirometry

Bronchial Asthma

Management of Asthma

Attention should be paid to preventing fetal hypoxemia during attacks. Thus, administration of supplemental oxygen to keep maternal oxygen saturation greater than 95% is recommended.

Patient education on avoiding triggers for asthma, decresing frequency of attacks.

Drug therapy including :1. Reliever medications (short actingβ2agonists).2. Controller medications ( Corticosteroids, cromolyn

sodium, nedocromil sodium, sustained-release theophylline, and long-acting β-agonists).

Bronchial asthma

Special considerations during labor and delivery :

It is recommended that stable patients be given their usual medications during labor and

delivery.

If the patient has required chronic oral glucocorticoids, stress doses of parenteral steroids

should be given until 24 hours postpartum to prevent exacerbations during labor.

Oxytocin is the drug of choice for labor induction, a PGE2 suppository may be the safest of additional alternatives, since both

methylergonovine and PGF2α have been associated with bronchospasm and should be avoided.

Venous Thromboembolism

•Decreased venous tone and blood flow in the lower extremities, leading to venous stasis.•Compression of the inferior vena cava and left iliac vein by the uterus, leading to venous outflow obstruction and stasis.•An increase in several clotting factors and a decrease in fibrinolytic activity, leading to a hypercoagulable state.

Venous Thromboembolism

Symptoms of a DVT include calf pain and swelling, however some patients are asymptomatic.

Clinical symptoms of pulmonary embolism (PE) include the sudden onset of dyspnea, tachypnea, tachycardia, and pleuritic chest pain. In massive

PE, arrhythmias, syncope, and cardiovascular collapse may develop.

Venous Thromboembolism

Diagnosis

DVT

Venous Thromboembolism

Anticoagul

ants

• Warfarin is contraindicated

• Heparin is the drug of choice

• Low molecular weight heparin is a solid alternative.

Thro

mbolytic th

erapy

• Pregnancy is a relative contraindication to the use of thrombolytic therapy, and these should be used only in patients suffering from massive PE and cardiovascular instability

Vena cava

l filter

•The use of vena cava filters is indicated for those patients who cannot be anticoagulated or for those who have recurrent PE while on adequate anticoagulant therapy.

Management of DVT and PE

Amniotic Fluid Embolism

Amniotic fluid containing :

o Fetal Debriso Desquamated

cellso Meconiumo Lanugo hairo Mucin

Damaged fetal

membrane

Disruption of uterine veins

Sufficient Pressure gradient

Amniotic Fluid

Embolism

Pathogenesis

Amniotic Fluid Embolism

Premature rupture of membranes

Advanced age

Use of uterine stimulants

Multiparity

Meconium staining of amnion

Occurs during / shortly after delivery

Severe Dyspnea Hypoxemia, cyanosis

Skin rash may be present

CVS collapse

Seizures, Coma

DIC , ARDS

Sudden onset

Mechanical obstruction of the pulmonary

vasculatureAlveolar capillary

leak (ARDS) secondary to

extensive microembolic

insult.

Pulmonary edema due to left ventricular

failure. Anaphylaxis

due to sudden exposure to fetal antigen

Risk factors Clinical Picture

Amniotic Fluid Embolism

Diagnosis

•Mainly by exclusion, the only sure way of diagnosis is by cytologic examination of blood removed from the distal lumen of a pulmonary artery catheter showing contents of amniotic fluid

Treat

ment

•Largely supportive•Mortality ranges from 80-90 %

Aspiration pneumonia

Clini

cal picture

•Tachypnea•Cyanosis•Hypoxemia•Hypotension•Tachycardia•Bronchospasm

Diagn

osis

•Witnessed event•Suspicion supported by radiographic findings of isolated or diffuse lung infiltrates.

Trea

tme

nt

•Mainly supportive:•Oxygen•Bronchodilators•Ventilation

•Antibiotics should be started early if bacterial infection is suspected

Adult Respiratory Distress Syndrome

ARDS is diagnosed on the basis of:

Acute onset (within 1 week of known clinical insult)

Bilateral opacities on CXR (not explained by effusions, collapse, or nodules)

Respiratory failure not fully explained by heart failure or fluid overload (objective assessment such as echocardiogram recommended)

Severity of ARDS• Mild: 300 ≥PaO2/FiO2 >200 with PEEP >5 cm H2O• Moderate: 200 ≥PaO2/FiO2 >100 with PEEP >5 cm H2O• Severe: 100 ≥PaO2/FiO2 with PEEP >5 cm H2O.

Adult Respiratory Distress Syndrome

•Eleminate the cause if possible •Deliver the baby if patient can tolerate and baby is at safe gestational age•Supportive care:•IV fluids•Nutritional support•Antiinflammatories ( steroids)•Antibiotics•Cardiovascular support•Ventilatory support weather invasive or non invasive•ECMO

Pulmonary edema with pregnancy

Extra pulmonary causes

Preeclampsia

Tocolytic pulmonary edema

Cardiogenic pulmonary edema

Etc…

Advanced pneumonia

Aspiration pneumonia

ARDS

Negative pressure pulmonary edema

Negative pressure pulmonary edema (NPPE)

3 Mechanisms have been incriminated in NPPE

Marked negative intrathoracic pressure

Increased venous return

Sudden increase in pulmonary

microvascular pressure

Hypoxia and metabolic acidosis increase

vasoconstriction at the pre capillary level

Elevation of pulmonary

microvascular pressure alters pulmonary

capillary permeability

Acute relief of obstruction

Dissapearance of autoPEEP

Negative intrapulmonary

pressure

Pulmonary Edema

Negative pressure pulmonary edema (NPPE)StridorWorking accesory muscles of respirationHypoxia and declining SPO2

Frothy pink sputum

Clinical Picture

Develops within one hour, may be delayedMainly based on history of precepitating event.Chest Xray supports diagnosis

Diagnosis

o First priority is to releif obstruction and correct hypoxemia

o Mainainance of airway patency and supplemental O2

o Diuretics are often administeredo Ventilatory support by non-invasive or

invasive modalities may be required

TreatmentTreatment

• Spontaneous pneumothorax rarely occurs during pregnancy and labor

• Traumatic pneumothorax may occur and needs prompt evaluation and control

Causes

• Pleuritic chest pain associated with dyspnea, tachypnea and cyanosis

• Unilateral diminished air entry and limited chest expansion

Clinical presentation

• History and clinical examination• Confirmation by imaging studies if possibleDiagnosis

Pneumthorax

Pneumothorax

• Conservative in mild cases, hospitalization, supplementary O2 and follow up.

• Needle aspiration, needle drainage and chest tube insertion.

• For patients who have not received definitive surgical therapy, epidural anesthesia and forceps assistance are recommended to prevent increased intrathoracic pressure due to the expulsive efforts during the second stage of labor and possible worsening or recurrence of pneumothorax.

Treatment