Vomiting

Question 1

What are the distinguishing features of vomiting versus regurgitation

Answer 1

Vomiting
- active retching/abdominal effort: present
- prodromal signs: often present
- timing: variable time after eating
- description of food: often partly digested and bile and/or blood may be present

Regurgitation
- abdominal effort: absent
- prodromal signs: absent
- timing: often shortly after eating
- description of food: can be tubular in nature and undigested

Question 2

Explain the main pathways that stimulate the vomiting center

Answer 2

The vomiting center is in the brainstem (medulla) and there are four main pathways that stimulate it:
- peripheral sensory receptors (i.e., intra-abominal sensory receptors, heart and large vessels, pharynx)
- bloodborne substances can stimulate the chemoreceptor trigger zone (e.g., uremia, bacterial toxins, drugs)
- vestibular input (i.e., inflammation, motion sickness)
- higher CNS centers (i.e., fear, stress, inflammation)

Question 3

Explain why is it better to use nonionic iodinated agents for contrast radiography when a foreign body is suspected

Answer 3

Nonionic iodinated agents (e.g., iopamidol, iohexol) should be used because intestinal perforation may be present
- barium is irritating to the peritoneum
- oral iodine compounds are hypertonic and thus they may draw fluid into the stomach and intestines after PO administration, with the potential of creating further fluid and electrolytes imbalances in an already compromised patient