Diarrhea in critically ill patients in the intensive care unit is an underestimated but common problem. Data from a large number of published human studies support the hypothesis that the gastrointestinal tract contributes to morbidity and mortality in critically ill patients in the intensive care unit.
Gut dysfunction during enteral feeding
ANNA M BATCHELOR
Introduction
Problems with enteral feeding
Of the 24 patients who could be weighed, more than half lost weight during enteral tube feeding. Enteral tube feeding was discontinued in 84% of patients, and 66% of these discontinuations were judged to be due to avoidable causes.
Gastric physiology
Sepsis also results in slow gastric emptying, and this change may be one of the first signs of new sepsis in a patient previously successfully enteral fed. The presence of fat in the small intestine is the most potent inhibitor of gastric emptying, resulting in relaxation of the proximal stomach and decreased contractions of the distal stomach—when the fat is absorbed, the inhibitory stimulus is removed and productive gastric motility resumes.
Intestinal physiology
Nutrient density is sensed primarily in the small intestine by osmoreceptors and chemoreceptors, and transmitted to the stomach as inhibitory neural and hormonal messages that delay emptying by altering gastric motility patterns.
Critical illness and intestinal motility
However, it should be remembered that both of these studies are very small with only 11 and seven patients and are not representative of the general ICU population. There are also studies that have used the instillation of barium in different parts of the GI tract during surgery as a model for what happens in critical illness.
Assessment of gastric emptying
The study found that gastric emptying was slower in patients compared to volunteers, and the authors concluded that the 13C-octanoic acid breath test is a novel and useful bedside technique for measuring gastric emptying in critically ill patients. The area under the paracetamol level curve may be influenced by factors other than the rate of gastric emptying and the delivery of paracetamol from the stomach to the duodenum. Metabolism rate, excretion rate and volume of distribution are important. .
Improving gastric emptying
Blinded manual bedside method for placement of feeding tubes in the small intestine was compared with an ultrasound-assisted bedside technique in 35 critically ill patients. 13 All patients were hemodynamically stable, mechanically ventilated and required tube placement for short-term enteral feeding due to impaired gastric emptying. . This new technique obviously has the potential for rapid, accurate and safe feeding tube placement in patients requiring nutritional support.
Summary
The average time to place delivery tubes using this manual technique was 139 min. Standard feed tubes were placed under direct vision using a 22 mm optical scope through the feed tube.
Diarrhoea
MARK C BELLAMY
Definition of diarrhoea
A study by Guenter and Sweed2 addressed the problem of quantifying diarrhea in enterally fed patients. A major problem in determining whether diarrhea exists in enterally fed patients is the quantification of stool output.
Spectrum of diarrhoea
Although there are no clear definitions, most studies have criteria that use frequency and consistency to produce some sort of scoring system. Based on this need, Guenter and Sweed developed a stool output assessment tool, which they tested for validity and reliability.
Causes of diarrhoea
A large Spanish multicenter study was published by Montejo, commissioned by the Nutritional and Metabolic Working Group of the Spanish Society of Intensive Care Medicine and Coronary Units.7 The frequency of gastrointestinal complications in a prospective cohort of critically ill patients receiving enteral nutrition and the effects on nutrient administration and relationship to outcome were evaluated. Infectious causes of nosocomial diarrhea are due to intestinal pathogens in outbreak situations and virtually all causes are due to Clostridium difficile.
Prevention of diarrhoea
Five independent factors were associated with diarrhea in a multivariate analysis: fever or hypothermia, malnutrition, hypoalbuminaemia, previous cessation of oral nutrition, and presence of a site of infection. However, enteral nutrition with soluble partially hydrolyzed guar gum was shown to reduce the incidence of diarrhea in a cohort of non-critically ill medical-surgical patients.
Conclusion
Management of
NIGEL SCOTT
Resuscitation
Restitution
SNAP
Enteral nutrition should be preferred over parenteral nutrition if the majority of the intestine is available for digestion and absorption of food. Fistelography through the external opening(s) is often able to demonstrate the origin of the fistula.
Reconstruction
The role of octreotide in the early closure of fistulas in patients with postoperative enterocutaneous fistulas has been investigated.5 In the Scott et al. report, 19 patients were randomized double-blind to receive either octreotide (100g tds) for 12 days. by subcutaneous injection or 12 days of placebo injections. Fistula closure, defined as no fistula output for two consecutive days during the 12-day treatment period, was observed in only one patient receiving octreotide and three patients receiving placebo.
Rehabilitation
Outcome
The gut as the motor of organ failure
JOHN C MARSHALL
History
Nosocomial infection
A similar study in Canada revealed that nosocomial infection with common ICU pathogens was significantly associated with the severity of organ failure (Figure 4.1).4 The association between proximal gastrointestinal colonization and the development of nosocomial infection and multiple organ failure was investigated in a high at-risk population of critically ill surgical patients. These data suggest that the upper gastrointestinal tract is a reservoir of organisms that cause hospital-acquired infections.
Bacterial translocation
Postoperative septic complications developed in 104 patients (23%) and enteric organisms were responsible in 74% of patients. This study again showed that bacterial translocation is associated with the development of post-operative sepsis in surgical patients.
The role of endotoxin
Systemic levels of endotoxin and cytokines were also measured in a control group of seven patients undergoing internal carotid surgery. Portal blood endotoxin was detectable in 36% of patients who underwent aortic surgery after bowel manipulation and in 71% after clamp release.
The gut immune system
It has been suggested that reduced microbial stimulation during infancy and early childhood may impair the development of tolerance in the gut immune system. The proportions of aerobic bacteria in the intestinal flora were also higher in allergic children, and the opposite was true in anaerobes.
Feeding and nosocomial infection
The interaction between the intestinal flora and the intestinal immune system serves not so much to protect against bacteria in the gut, but to limit innate immunity against the bacteria present. In critically ill patients, if either the intestinal flora or the intestinal immune system is altered, systemic inflammation can be induced.
Decontaminating the gut
Mesenteric ischaemia
ULF HAGLUND, HELEN F GALLEY
Causes of ischaemia
Mesenteric vasculature
In chronic vascular insufficiency, blood flow in an individual system can be maintained through these collateral connections even when the arterial trunk is completely blocked, and the caliber of these connections can vary considerably. However, in up to 30% of people, the collateral connections between the superior and inferior mesenteric arteries, via the arch of Riolan and the marginal artery of Drummond, may be weak or nonexistent, making the area of the splenic flexure particularly vulnerable to acute ischemia. .
Splanchnic blood flow
Local factors appear to be mainly involved in coordinating tissue blood flow with metabolic needs. Importantly, endothelin-1 blockade restored mucosal blood flow and oxygenation, which may be of particular interest given the implications for maintaining mucosal integrity in low baseline conditions.
Classification of intestinal ischaemia
An increased metabolic rate can produce a decreased pO2, increased pCO2, and an increased level of adenosine, each of which can mediate a hyperemic response. Burgener and colleagues1 recently showed that endothelin-1 blockade in a porcine acute heart failure model improved mesenteric but not renal perfusion, illustrating the regional importance of endothelin-1-induced vasoconstriction.
Pathophysiology of intestinal ischaemia
Acute occlusion or hypoperfusion of a large mesenteric vessel usually results in transmural (gangrenous) ischemia of the small bowel and/or colon. The earliest event in intestinal ischemia is changes in the tip of the intestinal villi.
Ischaemia and sepsis
Thus, gut-derived lymph plays an important role in the onset of injury to external organs after shock, especially lung injury. Factors produced in the gut are transported to the systemic circulation by mesenteric lymphatics which empty into the thoracic duct, which is then drained into the systemic and especially pulmonary circulation.
Therapeutic approaches in the critically ill
Medical management of non-variceal upper
PAUL WINWOOD
Epidemiology of upper gastrointestinal bleeding
However, the subgroup of patients with upper GI bleeding who do not do well accounts for the overall mortality. First, age and the prevalence of comorbidity continue to increase among patients with upper gastrointestinal bleeding.
Patients on ICU
Origin of upper gastrointestinal bleeding
Pre-disposition to bleeding from ulcers
Clinical presentation and prognostic indicators
A number of endpoints have been used to assess patients with bleeding ulcers, including number of units of blood transfused, requirements for urgent surgery and mortality. Contributing factors to these criteria include the severity of the first bleed, whether rebleeding occurs, and the patient's age and comorbidities.
Endoscopic stigmata for the assessment of risk of re-bleeding
Risk factors for mortality
This simple numerical score (the "Rockall" score) can be used to categorize patients presenting with acute upper gastrointestinal bleeding according to risk of death. The Rockall score can also be used to help manage patients with upper gastrointestinal bleeding.
Strategies for management
Department of Health guidelines state that every hospital managing upper GI bleeding must have therapeutic endoscopy available 24 hours a day. Overall, 5% of patients with upper GI bleeding have surgery, although the rate of surgical intervention is up to four times higher in patients with upper GI bleeding admitted to surgical units than for those admitted to medical teams.19 In patients with acute upper GI bleeding surgical intervention is largely limited to the highest-risk patients and the continued high mortality in such patients is therefore to be expected.
Therapeutic options
Endoscopic treatment is not necessary in most patients with bleeding ulcers, only in those with clinical signs of severe bleeding (eg, hemodynamic instability with tachycardia, hypotension, or postural changes in blood pressure or pulse; falling hematocrit or need for transfusion). ) and endoscopic evidence of active bleeding or a visible vessel that is not bleeding. Additionally, early elective surgery after initial endoscopic hemostasis should be considered in elderly patients with comorbidity and/or hemodynamic instability who have active bleeding from an arterial ulcer controlled by endoscopic hemostasis.
Conclusions
Acute pancreatitis
JOHN R CLARK, JANE EDDLESTON
Initial events
Epidemiology
Aetiology
Circulating factors may have an effect on pancreatic function by affecting pancreatic blood flow or acinar function. Endothelin, an endothelium-derived peptide with vasoactive properties, may play a role in blood flow dysregulation in sepsis.
Grading the severity of the disease
In severe acute pancreatitis, there is no normal enhancement of contrast of all or part of the gland, which is consistent with pancreatic necrosis. The degree of necrosis and the degree of peripancreatic inflammation are combined to give a CT severity index, also known as the Balthazar score (Table 7.4).37 The score has been validated in terms of excellent correlation between the CT view of necrosis and the development of complications and death (Table 7.5).38 Table 7.4 Relationship between CT grading system and morbidity.37,38.
Pathophysiology of acute pancreatitis
Large pseudocysts may rupture leading to pancreatopleural or pancreatopericardial fistulas, or more commonly, pancreatic ascites, resulting in chemical peritonitis. Alternatively, pseudocysts may cause compression and obstruction of the duodenum and/or common bile duct.
Remote organ dysfunction
This is a sterile process that reflects the activity of digestive and lysosomal enzymes of the pancreas and leukocytes. Necrotic tissue provides a fertile medium for bacterial growth, and developing pseudocysts can become infected with bacteria or fungi, resulting in pancreatic abscess in 30–50% of cases.
Endothelial dysfunction and multiple organ dysfunction syndrome
Diabetic ketoacidosis or nonacidotic diabetic coma may be a feature, especially in patients with hyperlipidemia. All patients with severe acute pancreatitis develop pleural effusion, and 20% will develop acute respiratory distress syndrome (ARDS).
Clinical relevance of cytokines
Controversies in Management
Patients with severe acute pancreatitis experience increasing metabolic demands throughout the course of the disease,78 and therefore the provision of nutritional inputs is an essential part of supportive therapy. Both drugs also stimulate reticuloendothelial system activity and play a regulatory role, mostly inhibitory, in the modulation of the immune response.
Clinical Intervention
Prevalence and prediction of multiorgan failure and mortality in acute pancreatitis. J Crit Care. Endothelium-derived selectins in the development of organ dysfunction in acute pancreatitis. Crit Care Med.
