Gastrointestinal function in intensive care patients: terminology, definitions and management. Recommendations of the ESICM Working Group on Abdominal Problems

AGI grade I (risk of developing GI dysfunction or failure)—the function of the GI tract is partially impaired, expressed as GI symptoms related to a known cause and perceived as transient.

Rationale Condition is clinically seen as occurrence of GI symptoms after an insult, which expectedly has temporary and self-limiting nature.

Examples Postoperative nausea and/or vomiting during the first days after abdominal surgery, postoperative absence of bowel sounds, diminished bowel motility in the early phase of shock.

Management The general condition is usually improving and specific interventions for GI symptoms are not needed, except the replacement of fluid requirements by intravenous infusions. Early enteral feeding, started within 24–48 h after the injury, is recommended [17, 18] (grade 1B). The use of drugs impairing GI motility (e.g. catecholamines, opioids) has to be limited whenever possible [19, 20, 21, 22] (grade 1C).

AGI grade II (gastrointestinal dysfunction)—the GI tract is not able to perform digestion and absorption adequately to satisfy the nutrient and fluid requirements of the body. There are no changes in general condition of the patient related to GI problems.

Rationale The condition is characterized by acute occurrence of GI symptoms requiring therapeutic interventions for achievement of nutrient and fluid requirements. This condition occurs without previous GI interventions or is more severe than might be expected in relation to the course of preceding abdominal procedures.

Examples Gastroparesis with high gastric residuals or reflux, paralysis of the lower GI tract, diarrhoea, intra-abdominal hypertension (IAH) grade I (intra-abdominal pressure (IAP) 12–15 mmHg), visible blood in gastric content or stool. Feeding intolerance is present if at least 20 kcal/kg BW/day via enteral route cannot be reached within 72 h of feeding attempt.

Management Measures to treat the condition and to prevent the progression to GI failure need to be undertaken (e.g. treatment of intra-abdominal hypertension [23], grade 1D; or measures to restore the motility function of GI tract, such as prokinetic therapy [24, 25, 26], grade 1C). Enteral feeding should be started or continued; in cases of high gastric residuals/reflux or feeding intolerance regular challenges with small amounts of enteral nutrition (EN) should be regularly considered (grade 2D). In patients with gastroparesis, initiation of postpyloric feeding should be considered in this state, when prokinetic therapy is not effective (grade 2D).

AGI grade III (gastrointestinal failure)—loss of GI function, where restoration of GI function is not achieved despite interventions and the general condition is not improving.

Rationale Clinically seen as sustained intolerance to enteral feeding without improvement after treatment (e.g. erythromycin, postpyloric tube placement), leading to persistence or worsening of MODS.

Examples Despite treatment, feeding intolerance is persisting—high gastric residuals, persisting GI paralysis, occurrence or worsening of bowel dilatation, progression of IAH to grade II (IAP 15–20 mmHg), low abdominal perfusion pressure (APP) (below 60 mmHg). Feeding intolerance is present and possibly associated with persistence or worsening of MODS.

Management Measures to prevent worsening of GI failure are warranted (e.g. monitoring and targeted treatment of IAH [23], grade 1D). Presence of undiagnosed abdominal problem (cholecystitis, peritonitis, bowel ischaemia) should be excluded. The medications promoting GI paralysis have to be discontinued as far as possible [19, 20, 21, 22] (grade 1C). Early parenteral feeding (within the first 7 days of ICU stay) supplementary to insufficient enteral nutrition is associated with higher incidence of hospital infections and should be avoided [27] (grade 2B). Challenges with small amounts of EN should be regularly considered (grade 2D).

AGI grade IV (gastrointestinal failure with severe impact on distant organ function)—AGI has progressed to become directly and immediately life-threatening, with worsening of MODS and shock.

Rationale Situation when AGI has led to an acute critical deterioration of the general condition of the patient with distant organ dysfunction(s).

Examples Bowel ischaemia with necrosis, GI bleeding leading to haemorrhagic shock, Ogilvie’s syndrome, abdominal compartment syndrome (ACS) requiring decompression.

Management Condition requires laparotomy or other emergency interventions (e.g., colonoscopy for colonic decompression) for life-saving indications [28, 29, 30] (grade 1D). There is no proven conservative approach to resolve this situation.

As differentiation of the acute GI problem from previously existing chronic condition might be very difficult, we suggest using the same definitions also in cases where the condition (e.g. GI bleeding, diarrhoea, etc.) might be due to a chronic GI disease (e.g. Crohn’s disease). In patients on chronic parenteral feeding, GI failure (equal to AGI III) should be considered chronically present, and no new acute interventions to restore function are indicated. However, monitoring of IAH and exclusion of the new acute abdominal problems should be performed similarly as in AGI grade III management.

IAH is present if IAP is found to be 12 mmHg or higher, confirmed by at least two measurements, 1–6 h apart [37].

Rationale Normal IAP is around 5–7 mmHg [38]. There are inherent variations and fluctuations in the IAP. IAH should also be considered present if the mean of the IAP measurements of the day is 12 mmHg or higher provided that at least four measurements were performed [39].

Management Monitoring of fluid resuscitation is necessary to avoid over-resuscitation [23] (grade 1C). Continuous thoracic epidural analgesia may decrease IAP in postoperative patients with primary IAH [40] (grade 2B). Nasogastric/colonic decompression is suggested for evacuation of intraluminal contents [23] (grade 2D). In patients with intraperitoneal fluids, percutaneous catheter decompression is recommended [23] (grade 1C). Elevation of head of bed above 20° should be considered as an additional risk for development of IAH [23] (grade 2C). Neuromuscular blockade decreases the IAP [41], but due to many undesirable effects it should be considered only in selected patients (grade 2C).

Abdominal compartment syndrome (ACS) is defined as a sustained (minimally two standardized measurements, performed 1–6 h apart) increase in IAP above 20 mmHg with new onset organ failure [37].

Management Although decompression remains the only definite management for ACS, the exact indications and timing of this procedure still remain controversial [42]. Currently it is recommended (1) to perform surgical decompression as a life-saving intervention in patients with ACS that is refractory to other treatment options [28, 43] (grade 1D), and (2) to consider pre-emptive decompression at the time of laparotomy in patients who demonstrate multiple risk factors for IAH/ACS [23] (grade 1D). In most severe cases of ruptured abdominal aortic aneurysm or abdominal trauma the initial use of mesh closure avoids development of ACS [44, 45] (grade 1C).

Vomiting (emesis) is the occurrence of any visible regurgitation of gastric content irrespective of the amount.

Rationale Vomiting is commonly defined as the oral expulsion of GI contents resulting from contractions of gut and thoracoabdominal wall musculature [46]. Vomiting is contrasted with regurgitation, which is the effortless passage of gastric contents into the mouth [46]. In ICU patients the forcefulness of the act is often not detectable; therefore, regurgitation and vomiting should be assessed together.

Management Several guidelines for prevention and management of postoperative nausea and vomiting are available [47, 48, 49, 50, 51]. However, no studies have addressed management of vomiting in mechanically ventilated ICU patients; therefore, no specific recommendation can be given.

Gastric residual volume could be considered high if a single volume exceeds 200 ml [52, 53, 54].

Rationale There is no sufficient scientific evidence or physiological ground to define precise values for high gastric residuals [53, 55]. Measurement of gastric residuals is neither standardized nor validated [56]. It has been suggested that gastric residual volume greater than 200 ml should prompt careful bedside evaluation, but automatic cessation of enteral nutrition solely on the basis on residual volumes of 200–500 ml should be avoided [53, 56, 57]. Despite the lack of scientific evidence, the members of the WGAP arbitrarily use total volumes of gastric residuals above 1,000 ml/24 h as a sign of abnormal gastric emptying, which requires specific attention.

Management Intravenous administration of metoclopramide and/or erythromycin is recommended for management of high gastric residuals, whereas cisapride is no longer approved [58] (grade 1B). Routine use of motility agents is not recommended [58] (grade 1A). Acupuncture stimulation may facilitate gastric empting in neurosurgical ICU patients [59] (grade 2B). Use of opioids and deep sedation should be avoided/reduced if possible. Cessation of gastric feeding is suggested if residual volumes exceed 500 ml per single measurement [57]. Here, postpyloric feeding should be considered [58] (grade 2D). Routine application of postpyloric feeding is not advocated [58] (grade 2D). Postpyloric feeding may cause severe small bowel dilatation and perforation in rare cases.

Diarrhoea is defined as having three or more loose or liquid stools per day with a stool weight greater than 200–250 g/day (or greater then 250 ml/day) [60, 61].

Rationale Normal bowel frequency ranges from three times a week to three times a day. Secretory, osmotic, motor and exudative diarrhoea may be distinguished [61], but in the ICU it is often better to distinguish between disease-, food/feeding- and drug-related diarrhoea [61, 62].

Management Symptomatic therapy—replacement of fluids and electrolytes, haemodynamic stabilization and organ protection (e.g. correction of hypovolaemia to prevent impairment of renal function) forms the basic management [61, 63, 64] (grade 1D). At the same time, trigger mechanisms need to be discovered and when possible stopped (e.g. laxatives, sorbitol, lactulose, antibiotics) or treated (e.g. malabsorption, inflammatory bowel disease). Feeding-related diarrhoea in critically ill patients may require reduction of infusion rate, repositioning of feeding tube, or dilution of nutrition formula. Changing formula by adding soluble fibre prolongs transit time [61, 64, 65, 66] (grade1C). Only in cases of severe or recurrent Clostridium difficile-associated diarrhoea is oral vancomycin superior to metronidazole [67, 68, 69] (grade 2C).

GI bleeding is any bleeding into the GI tract lumen, confirmed by macroscopic presence of blood in vomited fluids, gastric aspirate or stool.

Rationale Asymptomatic, endoscopically evident mucosal damage occurs in the majority of ICU patients [2]. Clinically evident GI bleeding reflecting considerable damage to GI mucosa may be seen in 5–25% of ICU patients [2]. Clinically important bleeding, defined as overt bleeding in association with haemodynamic compromise or the need for blood transfusions [70], occurs in 1.5–4% of mechanically ventilated patients [2, 70, 71].

Management In cases of clinically evident GI bleeding, the haemodynamic status dictates the approach. In cases of bleeding with haemodynamic instability endoscopy is the diagnostic tool of choice [72], but when bleeding is ongoing and massive, precluding adequate endoscopic assessment, angiography is appropriate (grade 2C). Early upper GI endoscopy (less than 24 h) is recommended [72, 73] (grade 1A), except for patients with acute variceal bleeding in whom a more expedite procedure (less than 12 h) should be considered [74] (grade 2C). Epinephrine injection can be used in combination with another method, such as clips, thermocoagulation or sclerosant injection [72] (grade 1A). Routine second endoscopy is not recommended, but in cases of rebleeding, a second attempt for endoscopic therapy is recommended [72] (grade 1A). In cases of a negative upper endoscopy with evidence of GI bleeding, colonoscopy should be performed, followed by small bowel exploration using push enteroscopy if colonoscopy is negative [75] (grade 2C). In cases of ongoing bleeding with negative endoscopies, abdominal surgery with intraoperative endoscopy or interventional radiology should be considered [76, 77] (grade 2C).

Paralysis of lower GI tract (paralytic ileus) is the inability of the bowel to pass stool due to impaired peristalsis. Clinical signs include absence of stool for three or more consecutive days without mechanical obstruction. Bowel sounds may or may not be present.

Rationale Outside of the ICU, the terms constipation and obstipation include uncomfortable or infrequent bowel movements, hard stool and painful defecation. Because these symptoms may not be expressed in ICU patients, it is suggested to use the term paralysis of lower GI tract. A cut-off level of 3 days has been used in most of the epidemiological ICU studies [78, 79].

Management Inhibitory drugs for GI motility (e.g. catecholamines, sedatives, opioids) must be withdrawn if possible and conditions impairing motility (e.g. hyperglycemia, hypokalaemia) corrected [19, 20, 21] (grade 1C). Because of their delayed onset of action, laxative drugs must be started early or given prophylactically [24, 25] (grade 1D).

Because of unknown long-term efficacy and safety the routine use of opioid antagonists cannot be recommended [80, 81] (grade 2B).

Prokinetics like domperidone, metoclopramide and erythromycin are used to stimulate the upper GI tract (stomach and small bowel), whereas neostigmine stimulates small bowel and colonic motility [25, 30]. Despite the lack of well-controlled studies and sufficient evidence, we recommend a standardised approach in using prokinetics for management of motility disorders [24, 25] (grade 1D).

Abnormal bowel sounds

Bowel dilatation is present if colonic diameter exceeds 6 cm (greater than 9 cm for caecum) or small bowel diameter exceeds 3 cm, diagnosed either on plain abdominal X-ray or CT scan [85, 86].

Rationale Bowel dilatation is a common sign in obstruction at any level of the GI tract. Bowel dilatation may also appear without an obstruction; the terms toxic megacolon following colitis and acute colonic pseudo-obstruction or Ogilvie’s syndrome, are used to describe acute severe colonic dilatation.

Management Next to the correction of fluid and electrolyte imbalance, nasogastric decompression may be helpful [29, 87] (grade 1D), although routine usage of nasogastric tubes after elective laparotomy is not recommended [88] (grade 1A). After exclusion of mechanical obstruction, intravenous neostigmine could be considered in patients with a caecal diameter >10 cm and without improvement within 24 h [29, 89] (grade 2B). Colonoscopy is recommended for non-surgical decompression in patients with a caecal diameter >10 cm and no improvement after 24–48 h of conservative treatment [29, 87, 90] (grade 1C). Colonoscopic decompression is effective in up to 80%, but carries a certain morbidity/mortality risk [30]. Conservative treatment together with colonoscopy may be continued for 48–72 h unless the caecum is >12 cm wide [30, 91] (grade 2C). In cases of unresponsiveness to conservative treatment, surgery is indicated due to the threatening risk of perforation [29, 30] (grade 1D). Usage of a laparoscopic technique with thoracic epidural anaesthesia where appropriate enhances bowel function after abdominal surgery [92, 93, 94] (grade 1B), and may therefore prevent bowel dilatation.