3. Vomiting (acute, chronic)

What can vomiting lead to?

There will be loss of stomach acid, causing:

- Chloride-responsive metabolic alkalosis

Ruptures of the esophagus, called:

- Mallory-Weiss syndrome

Most frequent disorder of gastric emptying?

Vomiting

- Defense mechanism used to get rid of potentially dangerous substances

What is vomit commonly preceded by?

Nausea

What is always increased during vomiting?

Parasympathetic tone

Vomiting involves?

- Closing the pylorus

- Retroperistaltic movements in the intestines

- High abdominal pressure (from diaphragm & contracting abdominal m.m.)

- Opening of the cardia

- Opening of lower esophageal sphincter

What happens to the heart during vomiting?

Increased abdominal pressure compresses inferior vena cava, decreasing the preload

= Compensatory tachycardia occurs

Parasympathetic tone will later cause bradycardia

What can evoke vomiting?

GI-related

- Gastritis

- Enteritis

- Hepatic congestion

- Mesenteric disorders

Diseases that cause severe pain

- AMI

- Kidney stone, gall stone

Hypersensitivity of the "vomit"-centre (area postrema)

- Pregnancy

- Hypocapnia

Bleeding into stomach

High intracranial pressure

Toxic substances & drugs

- Heavy metals

- Mushroom, alcohol, morphine

- Uraemic toxins

- Ketones

Psychological

- Fear, anxiety

- Sensory (taste, smell, sight, pain)

Motion sickness

Consequences of vomiting?

Not a big deal if it happens now and then, mostly causing mild salt, water- & acid loss

However, there may be some severe consequences

Severe consequences of vomiting?

In case of severe, strong vomiting;

- Strong forces can lacerate the esophageal mucosa -> causing hematemesis "Mallory-Weiss" syndrome

- Aspiration may occur (especially w/ disordered consciousness

What can the consequences of fluid loss during repeated vomiting lead to?

- There will be a significant loss of gastric acid, that metabolic alkalosis occurs

- There is high fluid loss, so exsiccosis occurs w/ hypovolemia -> causing secondary hyperaldosteronism:

= Tubules will be filled with K+ and H+, when they try to reabsorb Na+ to increase the body fluid volume

- Urine = kaliuria and aciduria

= Worsens the alkalosis & causes hypokalemia

What role does ADH play in vomiting?

- Nausea stimulates the release of ADH

- Hypovolemia stimulates the release of ADH

= May result in hypotonicity -> which further can induce more vomiting (perhaps due to increased intracranial pressure)

Acetonemic vomiting?

Called "Cyclic vomiting syndrome"

- Special case of chronic vomiting, mostly occurring in infants

One theory:

- A deficiency in gluconeogenetic enzymes are involved

= Causing infants to enter ketosis between meals -> as the liver cannot maintain a normal blood glucose level in the in-between meals periods.

Ketonaemia causes vomiting

More modern theory on acetonemic vomiting?

Involves a connection with migraines