CARDIOGENIC PULMONARY EDEMA

DEFINITION OF PULMONARY EDEMA

Acute pulmonary edema constitutes sudden accumulation of fluid in the lung tissue and alveoli due to either fluid redistribution as in hypertensive pulmonary edema, or fluid accumulation as in cardiogenic shock, due to pump failure

ETIOLOGY

RISK FACTORS WHICH MAY CONTRIBUTE TO WORSENING HEART FAILURE. 

Patients are prone to acute pulmonary edema if they have the following ethiologies:-

1.Acute coronary syndrome

2.Hypertensive emergency

3.Arrhythmia(such as AF or VT)

4.Pulmonary embolism

[Mmnemonic:CHAMP]

CLASSIFICATION OF CARDIOGENIC PULMONARY EDEMA

Cardiogenic pulmonary edema can be either classified into.

A.VASCULAR TYPE FLUID REDISTRIBUTION IN   WHICH THE HYPERTENSION PREDOMINANTES.

B. CARDIAC TYPE FLUID ACCUMULATION DUE TO PUMP FAILURE IN WHICH CONGESTION PREDOMINANTES. 

PATHOPHYSIOLOGY OF PULMONARY EDEMA

Pathophysiology of pulmonary edema is based on an imbalance of fluid reabsorption and filtration. INCREASED PULMONARY CAPILLARY PRESSURE quickly leads to fluid build up in the lungs and MASSIVELY IMPAIRED gas exchange, which explain the respiratory failure. Lung complaince and vital capacity decrease, airway resistance and range in path length to gas exchange increase. The pathophysiology of high altitude pulmonary edema may be explained by a combination of adecreased pulmonary oxygen content,pulmonary vasoconstriction and decreased alveolar pressure. 

CLINICAL FEATURES OF PULMONARY EDEMA

depending on the stage of pulmonary edema, symptoms may inclu

🔶Dyspnea and cough

🔶Thick mucus discharge

🔶Tachycardia

🔶Signs of cyanosis

🔶Restlessness

🔶Orthopnea

🔶Sharp breathing noises

🔶Moist rattling sounds

SPECIAL FORMS OF PULMONARY EDEMA

Progression of pulmonary edema can be divided into 4 stages:-

STAGE 1:- CONNECTIVE TISSUE EDEMA MEANING INTERSTITIAL PULMONARY EDEMA

◾️elevated LA pressure cause distension and opening of small pulmonary vessels

◾️at this stage,blood gas exchange doesn't deteriorate, or it may even be slightly improved

STAGE 2:- PROGRESSION IN TO ALVEOLAR PULMONARY EDEMA

◾️fluid and colloid shift into the lung interstitium from the pulmonary capillaries, but an initial increase in lymphatic outflow efficiently removes the fluid

◾️The continuing filtration of liquid and solutes may overpower the drainage capacity of the lymphatics.In this case, the fluid initially collects in the relatively complaint interstitial compartment which is generally the perivascular tissue of the large vessels,especially in the dependent zone

◾️The accumulation of liquid in the interstitium may compromise the small airways,leading to mild hypoxemia

◾️Hypoxemia at this stage is rarely of sufficient magnitude to stimulate tachypnea

STAGE 3:-INCREASED FLUID ACCUMULATIONAND FORMATION OF FOAM

◾️as fluid filtration continues to increase and the filling of loose interstitial space occurs,fluid accumulates in the relatively non complaint interstitial space

◾️The interstitial space can contain upto 50mL of fluid. With further accumulations,the fluid crosses the alveolar epithelium in to the alveoli, leading to alveolar flooding

◾️At this stage, abnormalities in gas exchange are noticeable. vital capacity and other respiratory volume are substantially reduced and hypoxemia become more severe

STAGE 4:- ASPHYXIA

DIAGNOSTIC METHODS

◾️PHYSICAL EXAMINATION AND HISTORY    

COLLECTION

   *aside from medical history and clinical picture,moist rattling sounds are noticeable in case of alveolar pulmonary edema. 

◾️BLOOD TEST

    *Routine;CBC

    *Liver function test

    *Renal function test

    *Arterial blood Gas analysis

    *serum cardiac biomarkers

    * level of B type Natriuretic peptide (BNP). 

      increased BNP indicates pulmonary edema is  

      caused by a heart condition. 

◾️️ECG

    The ECG may suggest acute tachyrhythmia or bradydysrhythnia or acute myocardial ischemia or infarction as the cause of cardiogenic pulmonary  edema

◾️ chest x ray

◾️ECHO TEST

  identifies the underlying heart defects. 

◾️CARDIAC CATHETERIZATION 

  cardiac catheterization is indicated when

  🔹cause remains uncertain

  🔹pulmonary edema which is refractory to 

      therapy

  🔹 Pulmonary edema accompanied by 

       hypotension

   CARDIOGENIC Vs NON CARDIGENIC PULMONARY EDEMA

🔶Cardiogenic pulmonary edema

  ▪️findings supporting cardiogenic edema

     *S3 gallop

     *elevated JVP

     *Peripheral edema

  ▪️Hypoxemia is due to ventilation perfusion

      mismatch. 

  ▪️Respond to administration of oxygen

  ▪️distinguishing X-Ray features in cardiogenic 

       cause

      *cardiomegaly

      *kerley B lines and loss of distinct vascular 

        margins

      *cephalization: enlargement of vasculature 

        to the apices

     *perihilar alveolar infiltration 

🔶Non-Cardiogenic pulmonary edema

  ◾️Pulmonary finding may be relatively normal 

      in the early stages

  ◾️Clincal picture ranges from mild dyspnea to

      respiratory failure despite CXR showing 

      diffuse alveolar infiltrates

  ◾️Hypoxemia is due to intra pulmonary shunt

  ◾️Persists despite oxygen supplementation

  ◾️distinguishing X-Ray features in non 

      cardiogenic cause

    *heart size is normal

    *uniform alveolar infiltrate

    *pleural effusion is uncommon

    *Lack of cephalisation

TREATMENT  OF CARDIOGENIC PULMONARY 

EDEMA

 🔶immediate general measures

 ◾️ immediate measure include,a sitting position

     with the legs dangling inorder to improve

     pulmonary vascular pressure,sedation, 

     administration of oxygen,and as diuretics, the

    immediate measure as well

 ◾️If the initial evaluation of a patient presenting

     with pulmonary edema reveals cardiogenic

    shock or respiratory failure,immediate CCU 

    admission is necessary. If the patient presents

    with respiratory failure,ventilatiory support

    using eithe non-invasive CPAP or intubation

    should be immediately implemented. 

🔶Specific treatment 

  ◾️vascular -type fluid redistribution requires 

     vasodilators(as nitrates)initially then diuretics

  ◾️cardiac type fluid accumulation requires

      diuretics first, thennitrates and ultrafiltration if no response to diuretics, as in patients with

     impaired kideney function.

patients in shock(cardiogenic shock)should be hypoperfused, also termed WET-COLD hypoperfusion.In this scenario, the patient also

requires vasopressors or inotropes

 LMNOP MMNEMONIC..

  ◾️Lasix(furosemide)

  ◾️Morphine

  ◾️Nitrates

  ◾️Oxygen

  ◾️Position(upright)

REFERENCE

 🔶▶️CARDIOVASCULAR PATHOLOGY FOR USMLE EXAM-2019 edition