Postoperative Nausea and Vomiting
This is one of the most common complaints following surgery, and its incidence ranges from 30 to 70 percent in high-risk patients (Møller, 2002). Those at risk for postoperative nausea and vomiting (PONV) include females, nonsmokers, those with prior motion sickness or prior PONV, and those with extended surgeries (Apfelbaum, 2003).
A multimodal approach to prevention is recommended (Apfel, 2004). Currently, combinations of 4 to 8 mg of dexamethasone prior to anesthesia induction are followed, toward the end of surgery, by less than 1 mg of droperidol (Inapsine) and 4 mg of ondansetron (Zofran). This pretreatment significantly reduces symptoms by 25 percent. However, if symptoms develop within 6 hours of surgery, antiemetics from a different pharmacologic class than previously administered are considered (Habib, 2004). Persistent nausea may benefit from combining agents from different classes (Table 42-7).
TABLE 42-7Commonly Used Medications for Nausea and Vomiting ||Download (.pdf) TABLE 42-7 Commonly Used Medications for Nausea and Vomiting
|Medication (Brand Name) ||Usual Dosage ||Route(s) |
| Antihistamines || Every 6 hr |
|Diphenhydramine (Benadryl) ||25–50 mg ||IM, IV, PO |
|Hydroxyzine (Atarax, Vistaril) ||25–100 mg ||IM, PO |
|Meclizine (Antivert) ||25–50 mg ||PO |
| Benzamides || Every 6 hr |
|Metoclopramide (Reglan) ||5–15 mg ||IM, IV, PO |
|Trimethobenzamide (Tigan) ||250 mg ||IM, PO, PR |
| Phenothiazines || Every 6 hr |
|Prochlorperazine (Compazine) ||5–10 (25 PR) mg ||IM, IV, PO, PR |
|Promethazine (Phenergan) ||12.5–25 mg ||IM, IV, PO, PR |
| Serotonin Antagonists |
|Ondansetron (Zofran) ||8 mg every 8 hr ||IV, PO |
|Granisetron (Kytril) ||2 mg daily ||IV, PO |
|Dolasetron (Anzemet) ||100 mg daily ||IV, PO |
Bowel Function and Diet Resumption
Normal GI function requires synchronized motility, mucosal transport of nutrients, and evacuation reflexes (Nunley, 2004). However, following intraabdominal surgery, dysfunction of enteric neural activity typically disrupts normal propulsion. Activity first returns in the stomach and is noted typically within 24 hours. The small intestine also exhibits contractile activity within 24 hours after surgery, but normal function may be delayed for 3 to 4 days (Condon, 1986; Dauchel, 1976). Rhythmic colonic motility resumes last, at approximately 4 days following intraabdominal surgery (Huge, 2000). Passage of flatus characteristically marks this return of function, and stool passage usually follows in 1 to 2 days.
Postoperative feeding is most effective when started early. It improves wound healing, promotes gut motility, decreases intestinal stasis, raises splanchnic blood flow, and stimulates reflexes that elicit GI hormone secretion to shorten postoperative ileus (Anderson, 2003; Braga, 2002; Correia, 2004; Lewis, 2001). The decision to initiate “early feeding” with liquids or with solid food has been studied prospectively (Jeffery, 1996). In patients who were given solid food as the first postoperative meal, the number of calories and amount of protein consumed on the first postoperative day were higher. In addition, the number of patients requiring diet changes to NPO (nil per os) was not statistically different (7.5 percent in regular diet and 8.1 percent in the clear diet groups). The improved tolerance and better palatability of solids makes this a reasonable option.
Postoperative ileus (POI) is a transient impairment of GI activity that leads to abdominal distention, hypoactive bowel sounds, nausea and vomiting related to GI gas and fluid accumulation, and delayed passage of flatus or stool (Livingston, 1990).
The genesis of POI is multifactorial. First, bowel manipulation during surgery leads to production of contributory factors. These include: (1) neurogenic factors related to sympathetic overactivity, (2) hormonal factors related to the release of hypothalamic corticotropin-releasing hormone (CRH), which plays a key role in the stress response, and (3) inflammatory factors (Tache, 2001). Second, perioperative opioid use also increases POI rates. Thus, in selecting opiates, clinicians balance the beneficial analgesia produced by central opioid receptor binding against the GI dysfunction that results from peripheral receptor binding effects (Holzer, 2004).
No single treatment defines POI management. Electrolyte repletion and IV fluids to reestablish euvolemia are traditional. In contrast, routine nasogastric tube (NGT) decompression to promote bowel rest has been challenged by multiple prospective randomized trials. A metaanalysis including nearly 5240 patients found routine NGT decompression unsuccessful and inferior to its selective use in symptomatic patients. Specifically, patients without NGTs had significantly earlier return of normal bowel function and decreased risks of wound infection and ventral hernia (Nelson, 2007). Additionally, tube-related discomfort, nausea, and hospital stays were reduced. For these reasons, postoperative NGTs are recommended only for symptomatic relief of abdominal bloating and recurrent vomiting (Nunley, 2004).
Gum chewing after laparotomy as a preventive modality for POI has been the focus of several small but randomized studies. In these, sugarless gum is usually chewed 15 to 30 minutes at least three times daily. In evaluations, this practice is associated with earlier improvement in bowel motility markers (Ertas, 2013; Jernigan, 2014). However, compared with placebo, gum chewing achieves these goals on average only several hours earlier (Li, 2013).
Obstruction of the small intestines may be partial or complete and can result from adhesions following intraabdominal surgery, infection, or malignancy. Of these, surgical adhesions are the most common cause (Krebs, 1987; Monk, 1994). Small bowel obstruction (SBO) develops following 1 to 2 percent of total abdominal hysterectomies, and nearly 75 percent of obstructions are complete (Al-Sunaidi, 2006). Obstruction may be remote from surgery, and the mean interval between primary intraabdominal procedure and SBO approximates 5 years (Al-Took, 1999).
Initial SBO management is similar to that for POI, but distinguishing between the two is important to prevent serious SBO sequelae. During SBO, the bowel lumen dilates proximal to the obstruction, and decompression may develop distally. Bacterial overgrowth in the proximal small bowel can promote bacterial fermentation and worsening dilation. The bowel wall also becomes edematous and dysfunctional (Wright, 1971). Progressive increases in bowel pressure compromise perfusion to the intestinal segment and can ultimately lead to ischemia or rupture (Megibow, 1991).
Clinical signs that may help distinguish SBO from POI include tachycardia, oliguria, and fever. Physical examination may reveal abdominal distention, high-pitched bowel sounds, and an empty rectal vault during digital examination. Last, leukocytosis with a neutrophil dominance should alert to possible coexistent bowel ischemia.
Computed tomography (CT) scanning is the primary imaging tool to identify SBO. Water-soluble contrast can safely help identify the cause and severity of an obstruction. Gastrografin, the most commonly used water-soluble dye, is a mixture of sodium amidotrizoate and meglumine amidotrizoate and may aid resolution of small bowel edema due to its high osmotic pressure. Gastrografin is also theorized to enhance smooth muscle contractility (Assalia, 1994). Although the use of oral Gastrografin does appear to reduce hospital length of stay, it has no therapeutic benefit in adhesion-related SBO (Abbas, 2007).
Treatment of SBO varies with the degree of obstruction. For partial obstruction, feedings are held, IV fluids and antiemetics are initiated, and an NGT is placed for significant nausea and vomiting. Continued surveillance monitors for signs of bowel ischemia. Symptoms in most cases of partial SBO improve within 48 hours. In contrast, for most of those with complete bowel obstruction, surgery to relieve the obstruction is indicated.
Colonic obstruction is rare following gynecologic surgery but carries a high mortality rate (Krstic, 2014). The colon can be obstructed by intrinsic lesions such as colon cancer or diverticulitis-related strictures or can be compressed by a pelvic mass or foreign body, such as a retained surgical sponge. An enlarged cecum found on an abdominal radiograph requires further evaluation by either a barium enema or colonoscopy. Immediate intervention is necessary when the cecal diameter exceeds 10 to 12 cm to minimize perforation risks.
Transient episodes of postoperative diarrhea are not uncommon after major gynecologic surgery as the GI tract returns to its baseline motility and function. Protracted episodes and excessive amounts of diarrhea almost always stem from infection and warrant further evaluation. Stool samples are examined for ova and parasites, cultured for bacteria, and assayed for Clostridium difficile toxin. Of potential etiologies, broad-spectrum antibiotics can impair normal GI flora growth and thereby promote C difficile toxin-associated pseudomembranous colitis. If toxin is identified, oral metronidazole or vancomycin is initiated and continued for 10 to 14 days after diarrhea resolution (Cohen, 2010). Regardless of the pathogen, aggressive fluid and electrolyte replacement is critical to prevent further aberrations that can delay recovery.
The primary goals of postoperative nutrition are to improve immune function, promote wound healing, and minimize metabolic disturbances. Despite the additional stress in the immediate postoperative period, underfeeding is accepted for a brief period (Seidner, 2006). Table 42-8 offers a summary of basic immediate postoperative metabolic needs. However, extended protein calorie restriction in a surgical patient can lead to impaired wound healing, diminished cardiac and pulmonary function, bacterial overgrowth within the GI tract, and other complications that increase hospital stays and patient morbidity (Elwyn, 1975; Kinney, 1986; Seidner, 2006). If substantial oral caloric intake is delayed for 7 to 10 days, nutritional support is warranted.
TABLE 42-8Postoperative Nutritional Requirements ||Download (.pdf) TABLE 42-8 Postoperative Nutritional Requirements
|Nutritional Requirements ||Recommendations |
|BEE in women ||65.5 + 1.9 (height in cm) + 9.6 (weight in kg) - 4.7 (age in years) |
|Total calories ||100% to 120% BEE |
|Glucose ||50–70% total caloric intake. Maintain blood glucose level <200 mg/dL |
|Protein ||1.5 g/kg/d of current weight (BMI <25) |
| ||2.0 g/kg/d of ideal weight (BMI >25) |
In the absence of contraindications, enteral nutrition is preferred to a parenteral route, especially when infectious complications are compared (Kudsk, 1992; Moore, 1992). Other advantages of enteral nutrition include fewer metabolic disturbances and lower cost (Nehra, 2002).