What Do You Mean By Pulmonary Edema?
Pulmonary edema can be defined as the condition that is characterized by the accumulation of fluid in the lungs which is usually caused by the extravasation of fluid from the pulmonary vasculature into the interstitium and air sacs of the lungs.
Pulmonary edema leads to exchanging of the impaired gas which causes respiratory failure. It is due to failure of the left ventricle of the heart to remove blood from pulmonary circulation, or injury to the lung tissue or blood vessels of the lungs.
Causes
Pulmonary edema is often caused by the congestive heart failure which means when the heart is unable to pump efficiently then the blood can back up into veins that take blood through the lungs.
As the pressure in these blood vessels rises then the fluid is pushed into the alveoli of the lungs in which the fluid reduces normal oxygen movement through the lungs.
Congestive heart failure leads to pulmonary edema that is caused by the following condition:
- heart attack or any disease of the heart that weakens the heart muscles.
- narrowed heart valves
- severe high blood pressure
Pulmonary edema may also be caused by:
- Kidney failure
- major injury
- certain medicines
- exposure to high altitude
- narrowed arteries that bring blood to the kidneys
- lung damage caused by the poisonous gas
- lung damage caused by infection
Symptoms
The symptoms of pulmonary edema include:
ACUTE ( short term )
- shortness of breathing
- feeling of suffocation
- anxiety, restlessness
- frothy sputum
- chest pain if it is caused by a cardiac abnormality
- papitation
- excessive sweating
- pale skin
CHRONIC ( long term )
- paraxosomal nocturnal dyspnea
- rapid weight gain
- loss of appetite
- fatigue
- swelling of ankle and leg
- orthopnea
Signs
- tachycardia
- confusion
- tachypnea
- anxious
- hypertension
- cool extremities
- wheezing
- rales
- diaphoric
Special Consideration
1) Unilateral pulmonary edema after the evacuation of pneumothorax
- findings may be apparent only by the radiology.
- Dyspnea with the physical findings localized to the edematous lung
2) Lymphatic blockage secondary to fibrotic and inflammatory diseases.
- both clinical, as well as radiographic manifestations, are dominated by the underlying disease.
3) Neurogenic pulmonary edema
- symptoms that occur within the minutes to an hour of the injury.
Investigations
1) CXR-PA view:
Unilateral or bilateral involvement, cardiogenic or noncardiogenic pattern that includes the air bronchogram signs, opacities by involving the lobar in the post-infectious pulmonary edema.
2) ABG analysis:
Hypoxia and hypocapnia with respiratory alkalosis and hypercapnia in the later stage with respiratory metabolic acidosis.
3) Hemodynamic measurement with the Swan-Ganz catheter
4) Blood work up as well as septic screen.
Management Therapy
- Treat underlying cause that includes sepsis, high altitude, hypoxia, fluid overload, hypoproteinemia, obstruction, heart failure, etc.
- Respi support that includes the NIV vs Intubation f/b venti support
Indication for intubation f/b venti support
- Refractive hypoxia
- Excessive work of breathing rate> 35/min, MV>12L/min.
- inability to protect airway
- rapid clinical deterioration
- hemodynamic instability
iii. NIV support: CPAP
Reasonable initial venti settings are EPAP of around 7 cm H2O and IPAP of around 15cm H2O with adjustment according to the tolerance of the patient.
Decreased work of breathing, FRC is increased, the collapse of alveoli due to edema fluid is prevented which helps in opening of collapsed alveoli.
A good response is observed in 30 minutes, if worsening is seen then consider an elective intubation f/b venti support.
Treatment In Special Condition
1) High altitude pulmonary edema
Slow ascent, prophylactically tab. nifedipine 20 mg sustained-release 8 hrly or inhaled salmeterol.
Descent and supplemental O2 are definitive treatments if descent is not possible and O2 is not available then start the pharmacotherapy in order to reduce the pulmonary artery pressure. Tab. nifedipine 10 mg sublingually f/b 20 mg SR tab 6 hourly. Also hydralazine, inhalation of the nitrous oxide acetazolamide are useful.
2) Post aspiration pulmonary edema
- Preop gastric emptying by physical means that is by using the Ryle’s tube aspiration or by the means of the pharmacology that includes the atropine, perinorm, etc.
- induction in lateral position
- supportive steroids
- head low position
- anti-emetics drugs which are ondansetron, granisetron.
- bronchoscopic removal of aspirated material
- PEEP and mechanical venti till edema clears
Prevention
In those with heart disease, effective control of the symptoms of the congestive prevents pulmonary edema in which dexamethasone is widespread use for the prevention of pulmonary edema.
Complications
Some of the major complications of pulmonary edema are:
- leg swelling
- abdominal swelling
- arrhythmias
- pleural effusion
- swelling of the liver
- electrolyte disturbance
- protein enteropathy
- respiratory arrest
- death
- mesenteric insufficiency
- acute heart attack
