Assessing nausea and vomiting

Nausea and vomiting in children with palliative care needs

Nausea and vomiting are commonly experienced by children with serious illnesses. Nausea is not always accompanied by vomiting and children who vomit are not always necessarily nauseous. Understanding the underlying cause or trigger factor may help in choosing the correct anti emetic (anti-vomiting) drugs.

Causes

There are many physical causes of nausea and vomiting which act via direct (central) or indirect (peripheral receptor) mechanisms that can stimulate the vomiting centre in the brain. Psychological causes of nausea and vomiting include anxiety, fear and pain. Children also have a sensitive gag reflex and any irritation in the back of the throat may trigger vomiting. It is therefore important to assess the child fully to identify the underlying causes and mechanisms before treating the child.

Note: There are multiple central and peripheral receptors with neurotransmitter pathways that stimulate the vomiting centre in the medulla oblongata of the brain stem. Vomiting is usually triggered by the stimulation of either the vagal afferent receptors in the gut, the vestibular apparatus or direct stimulation of the vomiting centre in the medulla.

Vomiting triggers

There are generally four (4) mechanisms that cause nausea and vomiting.

  • A mechanical mechanism which is caused by effects on the gut (gastrointestinal tract):

    • Oesophageal causes such as compression, mucosal inflammation due to reflux, or infections due to candidiasis or Herpes simplex.
    • Incomplete stomach emptying (gastric flow obstruction) e.g. partial or complete bowel obstruction, tumours, masses or constipation.
    • Any cause of slow stomach emptying (gastric stasis or poor gut motility).
    • Inflammation of the stomach mucosa from drugs e.g. non-steroids anti-inflammatory drugs (NSAIDs), steroids, antibiotics, and untreated anxiety.
    • Stimulation of receptors (vagal stimulation) in the gut which stimulate the vomiting centre in the brain.
    • Ascites or a large abdominal mass causing intra-abdominal pressure.
  • A “toxic” mechanism which stimulates receptors in the gut to send messages via the chemoreceptor trigger zone (CTZ) to the vomiting centre in the brain:

    • Drugs e.g. opioids, antibiotics chemotherapy, TB medication and anti-retroviral drugs.
    • Biochemical e.g. hypercalcaemia, uraemia, liver failure.
    • Toxins from tumour breakdown or infections.
  • Direct effects on the vomiting centre in the brain from triggers such as:

    • Raised intracranial pressure.
    • Brain metastases or primary brain tumours.
    • Radiotherapy to the brain.
    • Pain, fear, memories and anxiety can be major triggers of nausea and vomiting in children.
  • Vestibular (inner ear) effects from:

    • Motion sickness
    • Cerebellar tumour

 Pathways to the vomiting centre in the brain

Assessing nausea and vomiting in a child

When assessing nausea and vomiting in a child you need to follow these steps:

  1. Take a full history, including all medication the child is receiving.
  2. Complete a clinical examination focusing particularly on the neurological and gastrointestinal systems.
  3. Identify the possible effects of the vomiting, e.g. dehydration.

Questions to ask when taking a history of the nausea and vomiting

To obtain a full history you would question the child, if they are old enough to give a history, as well as the caregiver (nursing staff and parents) about:

  • Whether they are experiencing feelings of nausea or not.

  • Timing, frequency, consistency and volume of the vomiting.

  • The stool habits e.g. constipation or diarrhoea.

  • Any factors that may be contributing e.g. certain food or medications.

  • Any factors that may help reduce vomiting e.g. eating before taking medication.

  • Any neurological problems that may be contributing e.g. swallowing problems.

  • Any gastrointestinal problems that may be contributing e.g. gastro-oesophageal reflux.

  • Any pain or anxiety that may be contributing to the nausea.

  • Any movement or positioning that may trigger nausea and/or vomiting.

  • Any history of allergies.

Signs and symptoms and possible causes of nausea and vomiting

It is important that you identify the possible underlying cause of vomiting with a thorough history and examination before treating. Below is a table of common symptoms and their possible causes.

Symptoms and signs

Possible causes

Blood stained vomiting (haematemesis) Oesophagitis, swallowed blood, peptic ulcer, oesophageal varices
Coffee ground vomitus Upper gastrointestinal bleeding, stress ulceration, pre-terminal event, Disseminated Intravascular Coagulopathy (DIC)
Undigested milk/food Gastric outlet obstruction
Associated diarrhoea Gastro-enteritis
Projectile vomiting Raised gastrointestinal obstruction
Abdominal distension, decreased bowel sounds Ileus (a temporary lack of the normal muscle contractions of the intestines), electrolyte disturbances
Tender right upper quadrant, jaundice Hepatitis
Guarding and rebound tenderness Appendicitis, pancreatitis
Oliguria (low urine output), oedema  Renal failure
Chemotherapy, radiotherapy Toxicity, radiation enteritis
Bulging fontanelles, blurred disc margins, hypertension, bradycardia Raised intracranial pressure, hydrocephalus, space occupying lesion
Photophobia, meningism (neck stiffness) Meningitis
Smell of ketones, coma Diabetic ketoacidosis or other metabolic disorders
Associated headaches, blurred vision Migraines