An Outpatient Approach to Nausea and Vomiting
N/V is a common side effect of medications to varying degrees of clinical relevance. Most instances of drug-induced N/V are from activation of D2, 5HT3, H1, and M1 receptors and are dependent on the specific medication utilized. Some drugs, such as metformin, may cause N/V when administered without food; simply administering with food would save a beneficial drug from being discontinued due to unpleasant side effects. Classes of medications commonly associated with N/V include opiates, digoxin, dopamine agonists, hormones, and nicotine.
Cytotoxic medications used for cancer chemotherapy are especially tied to N/V, which is classified as postchemotherapy nausea and vomiting (PCNV) or chemotherapy-induced N/V (CINV). PCNV is further subdivided into the acute phase, which is N/V within 24 hours of chemotherapy; the delayed phase, which occurs after 24 hours postadministration of chemotherapy; and the anticipatory phase, brought about by the anticipation of chemotherapy administration. The treatment of PCNV varies on the emetogenicity of the chemotherapy agent used and usually necessitates more than one class of antiemetic.
Diseases that may induce N/V include gastroparesis, cyclic vomiting, migraine, gastric outlet obstruction, and peptic ulcer disease. Gastroparesis may be medication-induced or caused by physiological changes such as those found in patients with long-standing diabetes mellitus who rely on insulin for glucose control. Drugs that are found to induce gastroparesis include narcotics, clonidine, dopamine agonists, tricyclic antidepressants, calcium channel blockers, lithium, and progesterone.
Infectious causes of N/V are typically acute in onset and self-limiting. Viral gastroenteritis and bacterial sources may be responsible. For example, food poisoning from staphylococcal enterotoxin will typically present within 6 hours of ingestion, with symptoms lasting up to 48 hours.
Postoperative nausea and vomiting (PONV) may be experienced from inpatient or outpatient procedures. The overall incidence of N/V from outpatient procedures postdischarge has been estimated at 17% for nausea and 8% for vomiting. Symptoms may present and last up to 3 days after the procedure, making it difficult for providers to evaluate the patient for appropriate treatment in out-patient procedures. Pain, hypotension, dehydration, and anesthesia have been identified as risk factors for PONV, with treatment depending on the individual patient and on maximizing antiemetic therapy with multiple medications.
N/V related to motion sickness and vertigo is due to stimulation of the vomiting center located in the vestibular system. Sensory nerves located here contain H1 and M1 receptors.
Pregnancy is frequently associated with N/V and is commonly referred to as morning sickness. The incidence of pregnancy-induced N/V is high, with up to 70% of women reporting N/V in the first trimester. One mechanism behind N/V in pregnancy is human chorionic gonadotropin (hCG) stimulation of the CTZ. Women often experience most N/V in the first trimester when hCG levels are highest, though it can occur at any point throughout the pregnancy. Other factors contributing to N/V in pregnancy include elevated estrogen levels, gastric reflux, and hyperthyroidism.
Causes of N/V
Medications
N/V is a common side effect of medications to varying degrees of clinical relevance. Most instances of drug-induced N/V are from activation of D2, 5HT3, H1, and M1 receptors and are dependent on the specific medication utilized. Some drugs, such as metformin, may cause N/V when administered without food; simply administering with food would save a beneficial drug from being discontinued due to unpleasant side effects. Classes of medications commonly associated with N/V include opiates, digoxin, dopamine agonists, hormones, and nicotine.
Chemotherapy
Cytotoxic medications used for cancer chemotherapy are especially tied to N/V, which is classified as postchemotherapy nausea and vomiting (PCNV) or chemotherapy-induced N/V (CINV). PCNV is further subdivided into the acute phase, which is N/V within 24 hours of chemotherapy; the delayed phase, which occurs after 24 hours postadministration of chemotherapy; and the anticipatory phase, brought about by the anticipation of chemotherapy administration. The treatment of PCNV varies on the emetogenicity of the chemotherapy agent used and usually necessitates more than one class of antiemetic.
Disease States
Diseases that may induce N/V include gastroparesis, cyclic vomiting, migraine, gastric outlet obstruction, and peptic ulcer disease. Gastroparesis may be medication-induced or caused by physiological changes such as those found in patients with long-standing diabetes mellitus who rely on insulin for glucose control. Drugs that are found to induce gastroparesis include narcotics, clonidine, dopamine agonists, tricyclic antidepressants, calcium channel blockers, lithium, and progesterone.
Infections
Infectious causes of N/V are typically acute in onset and self-limiting. Viral gastroenteritis and bacterial sources may be responsible. For example, food poisoning from staphylococcal enterotoxin will typically present within 6 hours of ingestion, with symptoms lasting up to 48 hours.
PONV
Postoperative nausea and vomiting (PONV) may be experienced from inpatient or outpatient procedures. The overall incidence of N/V from outpatient procedures postdischarge has been estimated at 17% for nausea and 8% for vomiting. Symptoms may present and last up to 3 days after the procedure, making it difficult for providers to evaluate the patient for appropriate treatment in out-patient procedures. Pain, hypotension, dehydration, and anesthesia have been identified as risk factors for PONV, with treatment depending on the individual patient and on maximizing antiemetic therapy with multiple medications.
Motion Sickness
N/V related to motion sickness and vertigo is due to stimulation of the vomiting center located in the vestibular system. Sensory nerves located here contain H1 and M1 receptors.
Pregnancy
Pregnancy is frequently associated with N/V and is commonly referred to as morning sickness. The incidence of pregnancy-induced N/V is high, with up to 70% of women reporting N/V in the first trimester. One mechanism behind N/V in pregnancy is human chorionic gonadotropin (hCG) stimulation of the CTZ. Women often experience most N/V in the first trimester when hCG levels are highest, though it can occur at any point throughout the pregnancy. Other factors contributing to N/V in pregnancy include elevated estrogen levels, gastric reflux, and hyperthyroidism.
SHARE
