Page 1479 - Hall et al (2015) Principles of Critical Care-McGraw-Hill

1018 PART 9: Gastrointestinal Disorders

should be undertaken only when massive hemorrhage persists despite the presence of massive LGI bleeding, immediate angiographic or surgi-
nonsurgical therapy in a viable patient with treatable medical problems. cal intervention without endoscopic evaluation is indicated.
The different diagnostic and treatment modalities used in the man-
Prophylaxis: Since hemorrhage from SRMD presents a therapeutic agement of LGI hemorrhage (see Fig. 105-5) are outlined below. In
challenge and carries a high mortality, much attention has been given contrast to UGI hemorrhage, a role for adjunctive pharmacotherapy has
to prophylactic therapy. Despite the existence of SRMD in the setting not been established in LGI bleeding.
of low or normal acid secretion, prophylaxis has been directed toward
acid suppression or neutralization. The superior efficacy of intrave- ■ COLONOSCOPY
nous H RAs compared with sucralfate in preventing SRMD has been
2
demonstrated, and therefore, H RAs are preferred. Furthermore, prior Following the exclusion of a UGI source, an emergent colonoscopy
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2
concerns regarding the increased incidence of nosocomial pneumonia after a rapid oral purge is the initial examination of choice for diagnosis
with acid-suppressive therapy has not been observed in subsequent and treatment. Studies have indicated that following colonic cleansing,
studies. Oral and intravenous PPIs have also been used effectively for colonoscopy offers a higher diagnostic yield and a lower complication
prophylaxis. A recent meta-analysis showed that PPI prophylaxis sig- rate than the traditional angiographic approach. 91,95 An accepted bowel
nificantly decreased rates of clinically significant bleeding compared cleansing protocol is 4 L polyethylene glycol (golytely) given orally
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with H RA, without affecting the development of nosocomial pneumo- or via a nasogastric tube over 2 hours. Metoclopramide (10 mg) is
2
nia or mortality rates. However, the magnitude of this benefit and its administered at the start of the purge to facilitate intestinal transit and
88
cost-effectiveness are still unclear. In most patients, H RA should be a to minimize the risk of emesis.
2
sufficient regimen to prevent the development of SMRD. The overall diagnostic yield of emergent colonoscopy in LGI bleed-
In addition to pharmacologic therapy, adequate nutritional support ing is 69% to 80%. 91,96 Diverticular bleeding and angiodysplasia are
and, in particular, enteral nutrition have been shown to decrease the the most common findings in the majority of large series, with colitis
incidence of SRMD. 89,90 The prophylactic effect of enteral nutrition is (ischemic, inflammatory, or radiation induced), neoplasia, and anorectal
not mediated by an increase in gastric pH and instead may involve an disease being some of the minor etiologies. If an adequate colonoscopic
increase in gastric epithelial energy stores, which, in turn, maintain evaluation does not reveal a bleeding source, and an upper endoscopy
epithelial integrity and prevent necrosis and ulceration. Therefore, the is negative, a small intestinal etiology should be considered. Intubation
initiation of adequate nutrition support in the critically ill patient, pref- of the terminal ileum at the time of colonoscopy may be useful because
erably via the enteral route, may play a prophylactic role against SRMD. fresh blood emanating from the ileum may be indicative of small intes-
In the absence of a functional gastrointestinal tract, total parenteral tinal bleeding. Small bowel evaluation with push enteroscopy, capsule
nutrition (TPN), which has demonstrated a protective effect against endoscopy, or enteroclysis can be initiated once hemostasis is achieved
SRMD, can be considered, although the net effect may be harmful. 89 spontaneously or with nonendoscopic methods. A further discussion
regarding the evaluation of small intestinal bleeding will follow.
LOWER GASTROINTESTINAL HEMORRHAGE ■ ENDOSCOPIC THERAPY
LGI bleeding is defined as bleeding originating from a source distal to The hemostatic techniques used in therapeutic colonoscopy are similar
the ligament of Treitz. Hematochezia is the common presenting sign of to those used in therapeutic upper endoscopy. Both thermal coagulation
LGI bleeding, and the two frequent LGI sources are diverticulosis and and injection therapy with epinephrine have been used successfully to
angiodysplasia. However, in the patient with hematochezia and hemo- obtain hemostasis in acute LGI bleeding. With further expertise and
dynamic compromise, a briskly bleeding UGI source should be included advances in endoscopic technology, this relatively new field of therapeu-
in the differential diagnosis. Studies have indicated that as many as 10% tic colonoscopy is expected to evolve.
of patients suspected initially to have LGI bleeding ultimately are found
to have a UGI source, and an upper endoscopy should be strongly Diverticular Bleeding: The endoscopic visualization of a visible vessel or
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pigmented protuberance within a diverticular segment identifies patients
considered early in the management of these patients. LGI bleeding 97
continues to be an important problem, with some studies showing who are at high risk for persistent or recurrent diverticular bleeding. In
this setting, thermal coagulation or injection therapy with epinephrine
increasing rates of hospitalizations in the past 15 years. 92
In the past two decades, technologic advances in endoscopy have may be used individually or together to achieve successful hemostasis
greatly improved the diagnostic and therapeutic utility of colonoscopy (Fig. 105-6). Studies have suggested that endoscopic hemostasis may pre-
18,98,99
in LGI bleeding. The American society for Gastrointestinal Endoscopy vent recurrent diverticular bleeding and the need for hemicolectomy.
Therefore, endoscopic therapy offers a viable long-term alternative to
guidelines recommends colonoscopy in the “early” management of
severe acute LGI bleeding. However, the utility and optimal timing surgical therapy for diverticular bleeding in the elderly patient, who
93
may not be an ideal candidate for surgical intervention. However, mas-
of colonoscopy in these patients remain unclear. Some studies have
suggested that emergency therapeutic colonoscopy for acute LGI hem- sive diverticular bleeding may not be amenable to endoscopic therapy
because of poor endoscopic visualization or failed endoscopic therapy,
orrhage facilitates early control of bleeding, reduces rebleeding and
surgical intervention rates, and improves short-term morbidity thereby necessitating angiographic or surgical therapy.
and mortality. 17,18 Other studies have not confirmed those findings, and Angiodysplasia: Bleeding from angiodysplastic lesions is frequently
showed that use of urgent colonoscopy in severe LGI bleeding showed responsive to endoscopic therapy. These lesions are located often in
no evidence of improving clinical outcomes. 19,94 the cecum and right colon, and represent acquired arteriovenous mal-
The evaluation and management of LGI hemorrhage is outlined in formations. Successful hemostasis can be achieved with both injection
Figure 105-5. Most patients who experience severe LGI bleeding are therapy and thermal coagulation. The periphery of the lesion should
100
elderly, with an average age of 65, and have comorbidities, including be treated before the center in order to obliterate the feeder vessels.
cardiac and respiratory disease. Therefore, prompt resuscitative measures With respect to thermal coagulation, the recommended power
aimed at multiple-organ support should be initiated. As mentioned pre- settings are lower than those used for a bleeding peptic ulcer owing to
viously, in the setting of hematochezia and hypotension, a UGI source the increased risk of perforation in the right colon.
should be considered in the differential diagnosis. The presence of a posi- Additional lesions responsive to thermal and injection therapy
tive NG aspirate or historical risk factors for UGI bleeding should prompt include postpolypectomy sites, radiation colitis, and anorectal sources.
an emergent EGD. A negative NG aspirate and a clinical suspicion for an Noncontact modalities such as the argon-plasma coagulator (APC)
LGI source should lead to a diagnostic and potentially therapeutic colo- have been used effectively in the management of radiation colitis and
noscopy following a rapid oral purge with polyethene glycol (PEG). In postpolypectomy bleeding. In addition, a band ligation technique

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