Nausea is usually defined as the inclination to vomit or as a feeling in the throat or epigastric region alerting an individual that vomiting is imminent. Vomiting is defined as the ejection or expulsion of gastric contents through the mouth, often requiring a forceful event.
WHAT ARE THE CAUSES OF NAUSEA AND VOMITING?
Specific etiologies associated with nausea and vomiting are presented in Table 1–1.
Table 1–2 presents cytotoxic agents categorised by their emetogenic potential. Although some agents may have greater emetogenic potential than others, combinations of agents, high doses, clinical settings, psychological conditions, prior treatment experiences, and unusual stimuli to sight, smell or taste may alter a patient’s response to drug treatment.
The three consecutive phases of emesis are nausea, retching, and vomiting. Nausea, the imminent need to vomit, is associated with gastric stasis.
Retching is the laboured movement of abdominal and thoracic muscles before vomiting. The final phase of emesis is vomiting, the forceful expulsion of gastric contents due to GI retroperistalsis.
Vomiting is triggered by afferent impulses to the vomiting centre, a nucleus of cells in the medulla. Impulses are received from sensory centres, such as the chemoreceptor trigger zone (CTZ), cerebral cortex, and visceral afferents from the pharynx and GI tract. When excited, afferent impulses are integrated by the vomiting centre, resulting in efferent impulses to the salivation centre, respiratory centre, and the pharyngeal, gastrointestinal (GI), and abdominal muscles leading to vomiting.
WHAT ARE THE SIGNS AND SYMPTOMS OF NAUSEA AND VOMITING?
The clinical presentation of nausea and vomiting is given in Table1–3. Nausea and vomiting may be classified as either simple or complex.
Genomic Medicine UK is the home of comprehensive genomic testing in London. Our consultant medical doctors work tirelessly to provide the highest standards of medical laboratory testing for personalised medical treatments, genomic risk assessments for common diseases and genomic risk assessment for cancers at an affordable cost for everybody. We use state-of-the-art modern technologies of next-generation sequencing and DNA chip microarray to provide all of our patients and partner doctors with a reliable, evidence-based, thorough and valuable medical service.