Postoperative Nausea and Vomiting

Postoperative nausea and vomiting (PONV) constitute a relatively common complication after surgery. The incidence of nausea and vomiting varies with the surgical procedure, gender, age, obesity, anesthetic procedure, and analgesia used. A previous history of motion sickness and PONV also is an indicator of the likelihood of developing this postoperative complication. Factors associated with obesity that may contribute to a higher incidence of nausea and vomiting are a larger residual gastric volume, increased esophageal reflux, and increased risk for gallbladder and gastrointestinal (GI) disease. Fat-soluble anesthetics may also accumulate in adipose tissue and continue to be released long after anesthesia is discontinued. Pain not treated with appropriate analgesia may also induce nausea and vomiting. Surgical procedures that have a higher incidence of PONV are extraocular muscle and middle ear manipulations, testicular traction, and abdominal surgery. Women have a higher incidence of PONV, possibly because of hormonal differences. Children ages 11 to 14 years have the highest incidence based on age group. Patients who have had general anesthesia have a higher incidence of PONV than those who have had regional anesthesia; spinal anesthesia is generally associated with less PONV than general anesthesia, and peripheral regional anesthesia is the least emetogenic. Analgesics (e.g., morphine, fentanyl, alfentanil) used as premedication or with regional anesthetics frequently induce nausea and vomiting. Patients under nitrous oxide anesthesia have a higher incidence of nausea and vomiting than do those under halothane, enflurane, or isoflurane. Swallowed blood and gas accumulation in the stomach may also induce nausea and vomiting.

Motion Sickness

Nausea and vomiting associated with motion are thought to result from stimulation of the labyrinth system of the ear, with subsequent transmission of this stimulus to the vestibular network located near the VC. When there is strong or frequent stimulation, such as from a rocking ship or airplane, the vestibular network is bombarded with an abnormally high number of impulses that radiate by cholinergic nerve impulses to the adjacent VC. Thus, drugs that inhibit the cholinergic nerve impulses from the vestibular network to the VC should be effective in treating motion sickness.

Nausea and Vomiting in Pregnancy

The percentage of women reporting vomiting during the first 16 weeks of gestation is relatively constant at about 40%, decreasing to 20% from 17 to 20 weeks; only 9% of women report vomiting after 20 weeks of pregnancy. Vomiting is much more common among primigravidas, younger women, nonsmokers, African Americans, and obese women. Contrary to commonly held beliefs, vomiting is not more common in women who have experienced prior fetal losses or women with hypertension, proteinuria, or diabetes. There is also no association between vomiting and cohabitation; unplanned pregnancy; or gallbladder, liver, or thyroid disease.

Although traditionally described as “morning sickness,” most women report that symptoms of nausea and vomiting tend to persist to varying degrees throughout the day. The cause of morning sickness is unknown, but its occurrence and severity appear to be related to the levels of free and bound estradiol and sex hormone–globulin-binding capacity.

A woman with severe persistent vomiting that interferes with nutrition, fluid, and electrolyte balance may be experiencing hyperemesis gravidarum, a condition in which starvation, dehydration, and acidosis are superimposed on the vomiting syndrome. Hospitalization for fluid, electrolyte, and nutritional therapy may be required.

Psychogenic Vomiting

Psychogenic vomiting can be self-induced, or it can occur involuntarily in response to situations that the person considers threatening or distasteful (e.g., eating food whose origin is considered repulsive).

Chemotherapy-Induced Nausea and Vomiting

Chemotherapy-induced nausea and vomiting (CINV) is the most unpleasant adverse effect associated with the use of cancer chemotherapy. Many patients regard it as the most stressful aspect of their disease, more so even than the prospect of dying. Because the object of cancer therapy is at least to prolong life, the effect of CINV on the quality of life must be considered.

Three types of emesis have been identified in patients receiving antineoplastic therapy—anticipatory nausea and vomiting, acute CINV, and delayed emesis.

Anticipatory nausea and vomiting is a conditioned response triggered by the sight or smell of the clinic or hospital or by the knowledge that treatment is imminent. The onset of anticipatory nausea and vomiting is usually 2 to 4 hours before treatment and is most severe at the time of chemotherapy administration. Patients who experience anticipatory nausea and vomiting are more likely to be younger and to have received about twice as many courses of chemotherapy, with more drugs, for about three times as long as patients who do not experience this complication.

Patient factors also affect acute CINV. The incidence and severity of CINV are generally higher in younger people, women, those in poor general health, and those with metabolic disorders (e.g., uremia, dehydration, infection, GI obstruction). Patients with a history of motion sickness seem to be more sensitive to the emetic effects of cytotoxic agents. The patient’s outlook and attitude about cancer and therapy can significantly influence the frequency and severity of nausea and vomiting.

Delayed emesis occurs 24 to 120 hours after the administration of chemotherapy. The mechanisms are not known, but delayed emesis in patients receiving chemotherapy may be induced by metabolic by-products of the chemotherapeutic agent or by destruction of malignant cells. The emesis experienced is usually less severe than that which occurs acutely, but it still can be significant in reducing activity, nutrition, and hydration. Patients who have incomplete control of acute emesis often experience delayed emesis. Events that often trigger delayed nausea and vomiting are brushing teeth, using mouthwash, manipulating dentures, seeing food, and quickly standing up after getting out of bed in the morning.

Radiation-Induced Nausea and Vomiting

Another common cause of emesis associated with the treatment of cancer is radiation-induced nausea and vomiting (RINV). The use of high-energy radiation (also known as radiotherapy) from x rays, gamma rays, neutrons, and other sources to kill cancer cells and shrink tumors also induces nausea and vomiting, especially when concurrent chemotherapy is used. Radiation may come from a machine outside the body (external beam radiation therapy), or it may come from radioactive material placed in the body near cancer cells (internal radiation therapy, implant radiation). The frequency of RINV depends on the treatment site, field exposure, dose of radiation delivered per fraction, and total dose delivered.

Postoperative Nausea and Vomiting

As noted, there is no single cause of PONV, and therefore treatment with a single pharmacologic agent for all cases is unlikely. Measures such as limiting patient movement and preventing gastric distention can reduce PONV. Adequate analgesia can also forestall this complication. Nonsteroidal anti-inflammatory analgesics are not emetogenic (opioids are emetogenic) and should be given consideration if appropriate to the type of surgical procedure. Antiemetics used include dopamine antagonists, anticholinergic agents, and serotonin antagonists. The histamine-2 (H2) antagonists (e.g., cimetidine, ranitidine) also are occasionally used to reduce gastric secretions to minimize nausea and vomiting.

PONV is usually managed with an as-needed (PRN) order, but patients who are considered to be at moderate to high risk for PONV should be considered for prophylactic antiemetic therapy. In addition to minimizing the risk factors listed, a multimodal treatment approach is recommended because of the variety of receptor types associated with PONV. Therapy may include hydration, supplemental oxygen, a benzodiazepine for anxiolysis, a combination of antiemetics that work by different mechanisms (e.g., droperidol, dexamethasone, serotonin antagonist), intravenous (IV) anesthesia induction agents (e.g., propofol and remifentanil), and analgesia with a nonsteroidal anti-inflammatory drug (e.g., ketorolac) rather than an opioid. Nonpharmacologic techniques prior to surgery using acupuncture, transcutaneous electrical nerve stimulation, and acupressure stimulation have also been shown to reduce PONV.

The first step in treating PONV is to identify the cause. If a nasogastric (NG) tube is in place, check its patency and placement in preventing abdominal distention. Do not move an NG tube that was inserted during surgery (e.g., gastric resection); in this case, there is a danger of penetrating the suture line. Irrigation of a blocked NG tube may alleviate the nausea and vomiting. (A health care provider’s order to irrigate the NG tube is required.) Administration of PRN antiemetics when the patient first reports nausea will often prevent vomiting.

Motion Sickness

Most agents used to reduce nausea and vomiting from motion sickness are chemically related to antihistamines. The effectiveness of antihistamines in motion sickness probably results from their anticholinergic properties, not from their ability to block histamine.

Nausea and Vomiting in Pregnancy

In most cases, morning sickness can be controlled by dietary measures alone. The woman should be advised to eat small, frequent dry meals and to avoid fatty foods and other foods found to cause problems. Sometimes it may be difficult or impossible to work in the kitchen around food, and assistance may be required.

Psychogenic Vomiting

When a person has chronic or recurrent vomiting, a diagnosis of psychogenic vomiting is made after eliminating all other possible causes. The person with psychogenic vomiting usually does not lose weight and can control vomiting in certain situations (e.g., in public). Identification of the causes of psychogenic vomiting and successful resolution of the problem may not be possible. After an extensive workup eliminates other potential causes, a short course of an antiemetic drug (e.g., metoclopramide) or antianxiety drug may be prescribed, along with counseling.

Anticipatory Nausea and Vomiting

People with a negative attitude toward therapy, such as the belief that it will be of no benefit, are more likely to develop anticipatory nausea and vomiting. It tends to become more severe as treatments progress unless behavior therapy modifies the conditioned response. Such treatments include progressive muscle relaxation, mind diversion, hypnosis, self-hypnosis, systematic desensitization, music therapy, acupressure, and benzodiazepines (alprazolam, lorazepam). Nurses can play a significant role by maintaining a positive supportive attitude with the patient and making sure that the patient receives antiemetic therapy before each course of chemotherapy.

Chemotherapy-Induced Nausea and Vomiting

Antiemetic therapy to minimize acute CINV is based on the emetogenic potential of the antineoplastic agents used. Combinations of antiemetics are often used, based on the assumption that antineoplastic agents produce emesis by more than one mechanism. In general, all patients being treated with chemotherapeutic agents of moderate-to-high emetogenic potential should receive prophylactic antiemetic therapy before chemotherapy is started. Combinations of ondansetron, dolasetron, granisetron or palonosetron, dexamethasone, aprepitant, and possibly lorazepam and/or an H2 blocker (e.g., ranitidine) and/or a proton pump inhibitor (e.g., esomeprazole, pantoprazole) are often used. Antiemetic therapy should be continued for 2 to 4 days to prevent delayed vomiting. Emesis induced by moderately emetogenic agents may be treated prophylactically with a similar regimen and therapy should be continued for 24 hours. Dexamethasone with or without a phenothiazine (prochlorperazine) or metoclopramide is recommended if the chemotherapy has low emetic potential. Lorazepam and an H2 blocker or proton pump inhibitor (such as cited earlier) may be added to the antiemetic regimen, if necessary. Antiemetic therapy is not recommended with medications with minimum emetic risk, although prochlorperazine may be used to prevent delayed emesis. All antiemetics should be given an adequate amount of time before chemotherapy is initiated and should be continued for an appropriate time after the antineoplastic agent has been discontinued.

Delayed Emesis

In general, patients who have complete control of acute emesis have a much lower incidence of delayed-onset emesis. A combination of prochlorperazine, lorazepam, and diphenhydramine given orally 1 hour before meals has successfully controlled delayed emesis. Recent studies have indicated that providing optimal antiemetic therapy with the chemotherapy will significantly reduce the frequency of delayed emesis. Adding aprepitant, the neurokinin-1 (NK1) antagonist, in combination with a serotonin antagonist plus dexamethasone, significantly reduces the incidence of delayed emesis.

Radiation-Induced Nausea and Vomiting

Clinical guidelines recommend that patients who will be receiving radiation over a large portion of the body or those receiving single-exposure, high-dose radiation therapy to the upper abdomen should receive preventive antiemetic therapy. Granisetron and ondansetron, serotonin antagonists, with or without dexamethasone are approved and recommended to treat RINV. Patients at low to intermediate risk for RINV should receive granisetron, ondansetron, or prochlorperazine before each dose of radiation. Rescue medicines used to treat RINV include prochlorperazine and metoclopramide. Patients who require rescue antiemetic therapy should be pretreated with a serotonin antagonist before the next dose of radiation therapy.

Nursing Implications for Nausea and Vomiting

Nausea and vomiting are associated with illnesses of the GI tract and other body systems and with adverse effects of medications and food intolerance. Nursing care must be individualized to the patient’s diagnosis and needs at all times.