Non-Specific Conditions

Introduction

The difference between a condition and a disease is an important distinction to make.

A condition is a state that a patient is in. It is a descriptive term, and it is the result of a disease process.

To put it simply, a condition is not a diagnosis. It is a finding.

There are many non-specific conditions that patients can be in throughout respiratory medicine, the most common of which are detailed below.

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Respiratory Failure

This is found through the interpretation of an Arterial Blood Gas (ABG) sample.

There are 2 types: They are completely SEPERATE – one does NOT lead to another. They are caused by different disease processes.

Type 1- ↓O₂ and NORMAL CO₂  – hypoxaemia and normocapnia

• Due to a V/Q (ventilation/perfusion) mismatch – can be either due to:
  • ↓ventilation (asthma attack causing bronchoconstriction), normal perfusion
  • ↓perfusion (Pulmonary Embolism [PE]), normal ventilation

Type 2 – ↓O₂ and ↑CO₂ – Hypoxaemia and Hypercapnia

• Due to hypoventilation which reduces effective gas transfer
  • A result of anything that makes it harder to breath:
    • COPD, Obesity, Pneumonia, Rib Fracture, Opiates, MND, Nerve damage to muscles.

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Pleural Effusion

This is the build-up of excess fluid between the parietal and visceral pleura.

It is found on a CXR and analysed further using a sample from a chest drain installed to remove this excess fluid.

Chest Drains

In the continual review of a chest drains position there are two things to look for:

• Swinging – The backwards and forwards motion of drained fluid within the tube as the patient breathes. – This shows an intact pressure gradient. – Positive Finding.
  • A lack of swinging indicates incorrect insertion, or a possible pneumothorax.
• Bubbles– Air within drained fluid. This is normally present immediately after insertion. A later finding of bubbles is in keeping with a pneumothorax. This should be investigated further.

More information on the insertion process can be found in the following videos:

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Transudate vs Exudate

There are broadly 2 types of pleural effusion – TRANSUDATE and EXUDATE.

They have their own set of differentials.

The easiest way to categorise them is according to protein content:

• Transudate– LOW PROTEIN (<30g/L):
  • This is the result of a FAILURE in a body system:
    • Kidneys – through nephrotic syndrome causing increased albumin loss leading to reduced oncotic pressure within the blood.
    • Liver- Through liver cirrhosis causing reduced albumin synthesis- therefore reduced oncotic pressure.
    • Heart- Through congestive heart failure causing back-up of blood leading to stasis within the pulmonary vasculature, due to an ineffectively pumping heart.

• Exudate– HIGH PROTEIN (>30g/L):
  • This is the result of INFLAMATION in the body:
    • Autoimmunity (commonly rheumatoid arthritis)
    • Malignancy
    • Infection

The most accurate way to categorise these however is through Light’s criteria, however this is beyond the scope of this guide. More information can be found on: geeky medics.

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Cor Pulmonale

This is RIGHT heart failure ONLY arising from WITHIN the lungs or PULMONARY vasculature.

Important to note here- there are many causes of right heart failure.

One of the causes of right heart failure is Pulmonary Hypertension- the intermediate stage to Cor Pulmonale. When not resolved it progresses to right heart failure.

NOT all causes of pulmonary hypertension arise within the lungs. One of the most common causes is LEFT heart failure- causing back pressure into the lungs (pulmonary hypertension). [As this does not arise within the lungs/vasculature of the lungs it is NOT a cause of cor pulmonale specifically.

Causes of Cor Pulmonale:

Pulmonary Causes:

• COPD
• Interstitial Lung Disease
• Obstructive Sleep Apnoea
• Cystic Fibrosis

Vascular Causes:

• Pulmonary Embolism
• Connective tissue diseases (Sjorgen’s, systemic sclerosis)

This eventually, can lead to right heart failure due to increasing resistance within the pulmonary vasculature that the right heart cannot overcome.