Pulmonary Oedema Nursing Care of the Critically Ill Patient

Pulmonary Oedema refers to an accumulation of fluid in the interstitial spaces of the lungs that diffuses into the alveoli. This accumulation causes severe hypoxia. Thus, in pulmonary oedema nursing care, the patient’s oxygenation needs are prioritised.

Pulmonary Circulation VS Systemic Circulation

Pulmonary Oedema Pathophysiology

  1. excess vascular water fills the interstitium
  2. interstitial lymphatics situated within the pulmonary system are unable to drain excess water
  3. alveolar spaces flood and become unable to perform gas exchange due to ventilation/perfusion (V/Q) mismatch

RIGHT SIDE Heart Failure = Peripheral Oedema

LEFT SIDE Heart Failure = Pulmonary Oedema

Retrieved from https://www.otsuka.co.jp/en/health-and-illness/heart-failure/symptoms/ on 19th December 2022

Cardiogenic Pulmonary Oedema VS Non-Cardiogenic Pulmonary Oedema

Pulmonary oedema can be Cardiogenic Pulmonary Oedema a.k.a. Hydrostatic (pressure-related), Non-Cardiogenic Pulmonary Oedema (increased permeability), or a combination of both.

Cardiogenic Pulmonary Oedema a.k.a. Hydrostatic Oedema happens due to increased left ventricular filling pressure.

Non-Cardiogenic Pulmonary Oedema happens in the absence of elevated left ventricular pressure.

Pulmonary Oedema Signs & Symptoms + Radiographic Features

Pulmonary Oedema signs and symptoms onset is usually sudden, requiring immediate medical attention, usually due to intense dyspnoea resulting from the sudden V/Q Mismatch (happens when part of the lung receives oxygen without blood flow or blood flow without oxygen – respiratory reserve can help continue/preserve perfusion in V/Q mismatch, but only for a limited time), which leads to the patient becoming anxious and scared. Noisy respirations are also present due to secretions within the larynx and trachea. The patient’s skin becomes moist, cold and clammy – signs of shock.

Cyanosis develops rapidly in the late stage of respiratory failure. The patient develops a cough with copious frothy blood-stained sputum. Crepitations are heard throughout the chest on auscultation. A chest x-ray typically features a bat-like picture of the lungs. Note that a chest x-ray featuring pneumonia is very similar to one featuring pulmonary oedema, thus, in critical care it is important to distinguish between the two.

Full list of signs & symptoms of pulmonary oedema includes:

  • restlessness
  • anxiety
  • breathlessness
  • sense of suffocation
  • cyanotic nail beds
  • greyish skin tone
  • cold and moist hands
  • weak and rapid pulse
  • jugular vein distension
  • coughing
  • increasing foamy sputum
  • confusion and stuporous (as pulmonary oedema progresses)
  • rapid noisy moist-sounding breathing
  • significant decrease in oxygen saturation level
  • assessment includes crackles on auscultation
Retrieved from https://twitter.com/onsquares/status/1346344297214447616 on 18th December 2022

Cardiogenic Pulmonary Oedema Causes

  • Congestive Heart Failure (CHF) – the heart muscle doesn’t pump enough blood as it should, causing blood to back up, leading to fluid build-up in the lungs
  • Mitral Stenosis – narrowing of the valve between the two left heart chambers which reduces or blocks the blood flow into the heart’s left ventricle, leading to left-sided heart failure
  • Cor Pulmonale – a condition that causes the right side of the heart to fail
  • Myocardial Infarction a.k.a. heart attack – when blood flow to the heart muscle is blocked

Non-Cardiogenic Pulmonary Oedema Causes

  • Acute Respiratory Distress Syndrome – ARDS occurs when fluid builds up in the alveoli, keeping the lungs from filling with enough air; less oxygen reaches the bloodstream, depriving the organs of much needed oxygen to function adequately
  • Smoke Inhalation Burns

Pulmonary Oedema Nursing Care

  • record and monitor vital signs
  • administer high oxygen concentration to relieve cyanosis
  • position patient in an upright position or with legs and feet down or ideally dangling over the side of bed to promote better circulation – correct positioning increases the vital capacity of the patient’s lungs
  • reassure patient to reduce anxiety – do not leave patient alone
  • morphine can be administered to help further with the reduction of anxiety, as well as dilating peripheral circulation leading to a reduction in left ventricular pressure during diastole; IMPORTANT – morphine can depress the respiratory system, so never leave patient unattended
  • administer diuretics – monitor for medication effects including patient’s fluid and electrolyte levels; diuretics, especially if loop diuretics are administered, waste potassium and sodium; potassium administration may be required
  • bronchodilators can be used to relieve bronchospasm and facilitate bronchial toilet a.k.a. toilet bronchoscopy – a potentially therapeutic intervention to aspirate retained secretions within the endotracheal tube and airways and revert atelectasis; aspiration of airway secretions is the most common indication to perform a therapeutic bronchoscopy in the intensive care unit (ICU)
  • patients with pulmonary oedema are at times electively ventilated so that through PEEP,t further water leakage into the alveoli may be prevented
  • identify and treat primary cause eg. need for mitral valve prosthesis, opening blocked arteries etc.

NOTE: intubation and mechanical ventilation may be required if the patient’s condition worsens; haemodynamic monitoring (BP and PAWP) and ABGs act as guidance in artificial ventilation management.

NOTE: PAWP refers to Pulmonary Artery Wedge Pressure which is the pressure within the pulmonary arterial system that occurs when catheter tip ‘wedges’ in the tapering branch of one of the pulmonary arteries.


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Capillary Exchange, Haemodynamics and Blood Flow

The term haemodynamics refers to the physical principles of blood flow, with ‘flow’ being the amount of blood flow in a given time (mL/min). The cardiovascular system’s main aim is to keep blood flowing throughout the capillaries so that capillary exchange can happen.

Capillary exchange is a two-way traffic type movement of substances that occurs between the blood plasma and the interstitial fluid.

It is important to note that tissue perfusion occurs through capillary exchange, making the blood within the capillaries (which is usually around 250-300ml at a given time) the most important blood within the body.

Chemicals pass through capillary walls through 3 possible routes:

  • endothelial cell cytoplasm
  • intercellular clefts
  • filtration pores of the fenestrated capillaries

Movement through the capillary walls happen by:

  1. Diffusion: allows exchange through the use of the concentration gradient across a permeable membrane (eg. glucose, oxygen, carbon dioxide and waste);
  2. Transcytosis: through pinocytosis, fluid droplets are picked up by endothelial cells. Vesicles move across the cell and releases fluid through exocytosis (eg. fatty acids, albumin and hormones);
  3. Filtration: fluids and solutes from blood capillaries move into the interstitial fluid due to blood hydrostatic pressure (BHP), which is the pressure that water within the blood plasma exerts against blood vessel walls, and interstitial fluid osmotic pressure (IFOP), which is the opposing pressure of the interstitial fluid;
  4. Reabsorption: fluids and solutes from the interstitial fluid move into the blood capillaries due to blood colloid osmotic pressure (BCOP).

Starling’s Law of the Capillaries refers to the near equilibrium existing between the volume of liquid reabsorbed and the volume filtered. The discrepancy in filtration and re-absorption is normally absorbed back into circulation through the lymphatic system.

If filtration exceeds re-absorption in an excessive way, oedema becomes present due to the abnormal increase in interstitial fluid volume. Excessive filtration can be caused by an increase in capillary blood pressure and capillary permeability, while inadequate re-absorption can be caused by a decrease in the concentration of plasma proteins which in turn lowers the blood colloid osmotic pressure (BCOP).

Below you can find a collection of videos that can help provide a more visual approach to Capillary Exchange.

Capillary Exchange and Oedema animation

capillary exchange

Special thanks to the creators of the featured videos on this post, specifically Youtube Channels Alila Medical Media and Medicina Didactica.

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