Hemodynamic instability secondary to anemia from GI bleeding needs to be treated aggressively with volume and blood product resuscitation, large-bore IV access, and adequate hemodynamic monitoring. Vasopressors may be necessary to maintain an adequate MAP during resuscitation.
Identification of the source of bleeding is imperative to treatment. A thorough history and physical examination in addition to NGT placement are necessary.
ICU patients whose lungs are mechanically ventilated for greater than 48 hours; have coagulopathy, history of GI ulceration or bleeding within the last 12 months; or two of the following risk factors: sepsis, ICU admission longer than 7 days, occult bleeding of 6 days or longer, or daily use of 250 mg of hydrocortisone or an equivalent are at risk for stress-related mucosal damage.
Initiation of proton pump inhibitor therapy is recommended for upper GI bleeding. Prescribing proton pump inhibitors for 72 hours with endoscopic hemostasis decreases the risk for rebleeding, the need for surgery, and mortality.3, 4
EGD identifies the location and type of bleeding in 90% of cases and decreases the mortality from hemorrhage.13
IAH: A sustained IAP greater than 12 mm Hg (often causing occult ischemia) without obvious organ failure. The normal IAP is 0 to 5 mm Hg, but it varies with body habitus and different disease states.
There are many risk factors for IAH, and they include sepsis, large-volume resuscitation, abdominal masses, pancreatitis, peritonitis, hypothermia, and abdominal surgery. IAH increases patient morbidity and mortality.26, 27, 28
ACS: IAH greater than 20 mm Hg with at least one organ dysfunction or failure.
Bladder pressure measurements are a cost-effective, safe, and accurate instrument for identifying IAH and guiding therapy.32, 33, 34, 35, 36 Measurements are made by attaching a pressure-monitoring system to the injection port of a Foley catheter, and should be measured every 4 to 6 hours.
The physiologic changes in ACS (decreased preload, increased afterload, increased intrathoracic pressure) can result in hypotension, which can lead to mesenteric ischemia and AKI and hypoxemia. Unfortunately, aggressive treatment often leads to worsening IAH and continued clinical deterioration.
An IAP of 15 mm Hg can affect ICP, CPP, and cerebral blood flow. An increased intrathoracic pressure elevates central venous pressure and decreases venous drainage from cerebral vessels. Cerebral venous congestion leads to elevated ICP, resulting in intracranial hypertension (ICP greater than 20 mm Hg).
Medical management for intracranial hypertension should be initiated in patients with IAH and elevated ICP. Intracranial hypertension secondary to brain injury or IAH may be refractory to medical therapy. Decompressive laparotomy has been shown to be useful in decreasing ICP in traumatic brain injury patients with refractory intracranial hypertension.
APP should be calculated in patients with elevated bladder pressures. APP is calculated from the difference between the MAP and the IAP (APP = MAP − IAP). Hemodynamic therapy targets an APP of 60 mm Hg. In patients with an IAP of 20 mm Hg, a MAP of 80 mm Hg will likely maintain adequate perfusion pressure to the abdominal organs, including the kidneys, liver, and intestines.37, 53, 54, 55
The terminology of partial versus complete obstruction is based on abdominal radiographic evidence, and 65% to 80% partial obstructions resolve without surgery. The clinical feature of continuous abdominal pain is common in patients with strangulated bowel, but its presence is not definitive.
Contrast-enhanced CT is becoming the study of choice for SBO evaluation.
Postoperative adhesions and hernias cause 70% of SBO.
Common practice for nonstrangulated adhesive SBO involves the administration of Gastrografin. Gastrografin is a water-soluble, radiopaque, hypertonic liquid oral contrast that is used to diagnose and treat adhesive SBOs. It draws fluid into the lumen from the bowel wall, decreasing edema and promoting peristalsis.
Complications such as dehydration, infection, ischemia, and perforation can follow obstruction of the small bowel.
It is more difficult to obtain a history and to perform an abdominal examination in patients whose lungs are mechanically ventilated because they are often sedated and receiving analgesic medications.
A patient who has a ruptured appendix and peritonitis may have a similar presentation to a patient with strangulated bowel and ischemia. With a complicated abdominal history, partial SBO and peritonitis, the patient should continue on antibiotics for 3 to 5 days.