BIOMED - Pathophysiology

🧅 𝘈𝘴𝘤𝘪𝘵𝘦𝘴

What is Ascites?
Ascites is a condition wherein we have fluid collection in abdomen. This fluid accumulation increases the risk of infection, and greater fluid collections may put pressure on lungs, making it difficult for the person to breathe. Additionally, this fluid may move up into chest & surround the lungs, possibly leading to accumulation within the pleural space (pleural effusion) and subsequent lung collapse and heart shifting across the mediastinum.

Accumulation of fluids can be as much as 22 litres, and drainage of this fluid is regulated (eg, 10L per day) to avoid hypovolaemic shock. Ascites drainage is paired with the intravenous administration of Albumin (a blood product), such as 100mL of Albumin infused for every 2L drained in order to avoid shock.

Symptoms:
- Abdominal swelling & increased abdominal girth
- Peripheral oedema
- Sudden weight gain
- Bloating / feeling "full" or "heavy"
- Nausea, vomiting
- Indigestion & heartburn
- Fever
- Loss of appetite
- Shortness of breath / breathing difficulty
- Haemorrhoids

Pathophysiology of Ascites
Causes?
There are 3 theories on the causes of Ascites:

1. Underfilling
Inappropriate draining of fluid in the splanchnic vascular bed, likely due to portal hypertension and a drop in blood circulatory volume.

2. Overflow
Pressure due to intravascular hyper/hypovolaemia, causes overflow into peritoneal cavity, causing Potassium and Sodium imbalances.

3. Peripheral arterial vasodilation
Includes both of the above points.
Portal HTN ☞ vasodilation ☞ insufficient arterial blood volume.

As the condition furthers, Sodium in the body remains, thus the plasma volume expands, overflowing into the peritoneal cavity, and ∴ we end up with ascites.

Note:
The most common cause of Ascites is Cirrhosis of the liver, which is commonly brought about by alcohol consumption.

Further reading:

Nursing Interventions & Expectations
Weights are often a good indicator of how many litres of fluid a person has onboard, and how many we can expect to drain.

Drainage of Ascites is limited to a certain number of litres per day to avoid going into hypovolaemic shock, and drainage of fluid is paired with infusion of Albumin - a blood product which supports intravascular volume. This may be 100mL of Albumin infused for every 2L drained, etc, as per Drs. orders.

Diagnosis
Diagnosis incorporates patient history and physical examination, and abdominal ultrasound may confirm presence of Ascites.

Risk Factors
- Hep B infection
- Alcohol Abuse
- Severe liver disease (i.e. Cirrhosis)
- Cancer in abdominal organs
- Renal Failure
- Congestive Heart Failure

Medical Management
- Sodium restriction of 20-30mEg/dL
- Diuretics
- Water restriction (in persistent hyponatraemia)
- Albumin replacement therapy
- 24 hour urinary Sodium measurements in those with portal HTN to assess sodium levels, in response to diuretics and diet compliance.

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