Validation the use of refractometer and mathematic equations to measure dietary formula contents for clinical application.

BACKGROUND AND AIMS: Gastric residual volumes are widely used to evaluate gastric emptying for patients receiving enteral feeding, but controversy exists about what constitutes gastric residual volume. We have developed a method by using refractometer and derived mathematical equations to calculate the formula concentration, total residual volume (TRV), and formula volume. In this study, we like to validate these mathematical equations before they can be implemented for clinical patient care. METHODS: Four dietary formulas were evaluated in two consecutive validation experiments. Firstly, dietary formula volume of 50, 100, 200, and 400 ml were diluted with 50 ml water, and then the Brix value (BV) was measured by the refractometer. Secondly, 50 ml of water, then 100 ml of dietary formula were infused into a beaker, and followed by the BV measurement. After this, 50 ml of water was infused and followed by the second BV measurement. The entire procedure of infusing of dietary formula (100 ml) and waster (50 ml) was repeated twice and followed by the BV measurement. RESULTS: The formula contents (formula concentration, TRV, and formula volume) were calculated by mathematical equations. The calculated formula concentrations, TRVs, and formula volumes measured from mathematic equations were strongly close to the true values in the first and second validation experiments (R2>0.98, P<0.001). CONCLUSIONS: Refractometer and the derived mathematical equations may be used to accurately measure the formula concentration, TRV, and formula volume and served as a tool to monitor gastric emptying for patients receiving enteral feeding.

Preoperative issues in clinical nutrition.

Allowing a patient's nutritional state to deteriorate through the perioperative period adversely affects measureable outcome related to nosocomial infection, multiple organ dysfunction, wound healing, and functional recovery. Careful preoperative nutritional assessment should include a determination of the level of stress, an evaluation of the status of the GI tract, and the development of specific plans for securing enteral access. Patients already demonstrating compromise of nutritional status (defined by > 10% weight loss and serum albumin level < 2.5 g/dL) should be considered for a minimum of 7 to 10 days of nutritional repletion prior to surgery. Widespread use of total parenteral nutrition in unselected patients is unwarranted, may actually worsen outcome, and should be reserved for preoperative nutritional support only in severely malnourished patients in whom the GI tract is unavailable. Compared with the parenteral route, use of perioperative enteral feeding has been shown to provide more consistent and beneficial results, and can be expected to promote specific advantages in long-term morbidity and mortality.

Incomplete intestinal metaplasia in the diagnosis of columnar lined esophagus (Barrett's esophagus).

To investigate the distribution and specificity of intestinal metaplasia (IM) in columnar lined esophagus (CLE), the authors reviewed biopsies of the hiatal hernia pouch (HHP) and esophagus from 17 patients with CLE (84 biopsies) and 10 controls (25 biopsies). The proximal margin of the gastric folds was used as an endoscopic landmark, corresponding to the gastroesophageal muscular junction (GEMJ). No biopsies obtained above the GEMJ in control patients showed columnar mucosa. No goblet cell metaplasia was seen in 21 biopsies of the HHP from patients with CLE or in 13 corresponding biopsies from controls. In contrast, alcian blue (AB) stains showed diffuse acid mucins in 3 of 21 biopsies of the HHP from patients with CLE and in 10 of 13 corresponding biopsies from controls, demonstrating that goblet cell metaplasia clearly distinguishes biopsies of CLE from the HHP (P less than 0.01), whereas small amounts of diffuse acid mucin on AB stains do not. IM evidenced by goblet cell metaplasia was frequently seen in biopsies only 2-3 cm above the GEMJ, and CLE was limited to that area in three patients, suggesting that the distal esophagus cannot be dismissed as a site for metaplastic and possibly premalignant mucosa. Adenocarcinoma was diagnosed during the course of the study in one patient with only 5 cm of columnar mucosa above the GEMJ.

Artificial nutrition in pancreatic disease: what lessons have we learned from the literature?

Acute pancreatitis is a disease process that begins with an initial injury to the pancreatic acinar cell due to the erroneous premature activation and intracellular release of digestive enzymes. The local injury is amplified through the induction of a systemic inflammatory response, mediated by the generation and release of cytokines and an aggressive inflammatory cell recruitment. Failure to maintain gut integrity may exacerbate the stress response and the systemic inflammatory reaction associated with this process, worsening the overall clinical severity of the pancreatitis and contributing further to complications of organ failure and nosocomial infection. Emphasis in the clinical nutritional management of these patients has shifted from efforts to minimize stimulation of the gland, to attaining enteral access, starting tube feeds low in the gastrointestinal tract, and monitoring tolerance. While clinical guidelines help identify those patients with acute pancreatitis at greatest need for aggressive nutritional support, the proper timing to initiate feeding, the optimal composition of the enteral formula, and whether or not enteral feeding is better than no nutritional therapy is still not clear from the current literature.

Continuous nasogastric tube feeding: monitoring by combined use of refractometry and traditional gastric residual volumes.

BACKGROUND & AIMS: Traditional use of gastric residual volumes (GRVs) is insensitive and cannot distinguish retained enteral formula from the large volume of endogenous secretions. We designed this prospective study to determine whether refractometry and Brix value (BV) measurements could be used to monitor gastric emptying and tolerance in patients receiving continuous enteral feeding. METHODS: Thirty-six patients on continuous nasogastric tube feeding were divided into two groups; patients with lower GRVs (<75 ml) in Group 1, patients with higher GRVs (>75 ml) in Group 2. Upon entry, all gastric contents were aspirated, the volume was recorded (Asp GRV), BV measurements were made by refractometry, and then the contents were reinstilled but diluted with 30 ml additional water. Finally, a small amount was reaspirated and repeat BV measurements were made. Three hours later, the entire procedure was repeated a second time. The BV ratio, calculated (Cal) GRV, and volume of formula remaining were calculated by derived equations. RESULTS: Mean BV ratios were significantly higher for those patients in Group 2 compared to those in Group 1. All but one of the 22 patients (95%) in Group 1 had a volume of formula remaining in the stomach estimated on both measurements to be less than the hourly infusion rate (all these patients had BV ratios <70%). In contrast, six of the 14 patients in Group 2 (43%) on both measurements were estimated to have volumes of formula remaining that were greater than the hourly infusion rate (all these patients had BV ratios >70%). Three of the Group 2 patients (21%) whose initial measurement showed evidence for retention of formula, improved on repeat follow-up measurement assuring adequate gastric emptying. The remaining five patients from Group 2 (35%) had a volume of formula remaining that was less than the hourly infusion rate on both measurements. The pattern of Asp GRVs and serial pre- and post-dilution BVs failed to differentiate these patients in Group 2 with potential emptying problems from those with sufficient gastric emptying. CONCLUSIONS: Refractometry and measurement of the BV may improve the clinical utilization of GRVs, by its ability to identify the component of formula within gastric contents and track changes in that component related to gastric emptying.

Differentiating subtypes (hypoalbuminemic vs marasmic) of protein-calorie malnutrition: incidence and clinical significance in a university hospital setting.

Clinical nutrition assessment has identified two types of protein-calorie malnutrition (PCM), a stress-induced hypoalbuminemic form (HAF-PCM) and a marasmic form (MF-PCM) generated by adaptation to starvation. This study evaluated the differences between these two patterns of PCM with regard to precipitating factors and the clinical sequelae of mortality, cost of total parenteral nutrition, length of hospitalization, and rate of sepsis and nosocomial infection. Of 220 patients receiving total parenteral nutrition over a 12-month period (0.7% of 30, 127 admissions), 180 were included in this study. HAF-PCM was diagnosed in 45% and MF-PCM in 25% of study patients. HAF-PCM was more common in older age groups. Women had PCM less often than did men (57% vs 83%), but whereas men developed both forms of PCM equally, women were more likely to develop HAF-PCM. Prolonged mechanical ventilation increased the likelihood of both patterns, whereas the presence of malignancy, concomitant organ failure, trauma, burns, or surgery did not increase the likelihood of developing either pattern of PCM. HAF-PCM increased the length of hospitalization by 29% and the cost of total parenteral nutrition by 42%. The presence of HAF-PCM increased four-fold the odds of dying, and the odds of developing nosocomial infection and sepsis almost 2.5 times above that seen in its absence. MF-PCM had no clinical effect of its own on any of the outcome parameters, but instead exerted only an interactive synergistic effect with HAF-PCM on length of hospitalization and cost of total parenteral nutrition.

Comparison of the safety of early enteral vs parenteral nutrition in mild acute pancreatitis.

BACKGROUND: This prospective study was designed to compare the safety, efficacy, cost, and impact on patient outcome of early total enteral nutrition (TEN) vs total parenteral nutrition (TPN) in acute pancreatitis. METHODS: Patients admitted with acute pancreatitis or an acute flare of chronic pancreatitis, characterized by abdominal pain and elevated serum amylase and lipase, were randomized to receive either isocaloric and isonitrogenous TEN (via a nasojejunal feeding tube placed endoscopically) or TPN (via a central or peripheral line) started within 48 hours of admission. RESULTS: Thirty patients were studied over 32 admissions (TEN given on 16 and TPN on 16) for acute pancreatitis. There were no differences on admission in mean age, Ranson criteria, multiple organ failure score (MOF), or APACHE III score between TEN and TPN groups. Although slower to approach goal feeding over the first 72 hours of admission, TEN patients received 71.3% goal calories by day 4 vs 85.2% for TPN patients (not significant). There were no deaths and no differences between groups in serial pain scores, days to normalization of amylase, days to diet by mouth, serum albumin levels, or percent nosocomial infection. However, the mean cost of TPN per patient was over four times greater than that for TEN ($3294 vs $761, respectively, p < .001). Mean serial Ranson criteria, APACHE III, and MOF scores recorded every 2 to 3 days decreased in the TEN group, whereas those in the TPN group increased. Only the difference in the third Ranson criteria (mean 6.3 days after admission) for the TEN and TPN groups (0.5 vs 2.8, respectively) reached statistical significance (p = .002). Stress-induced hyperglycemia was worse in the TPN group, as serum glucose levels increased significantly over the first 5 days of hospitalization (p < .02), whereas those in the TEN group showed no significant change. An exacerbation of pancreatitis, occurring in one TEN patient when the nasojejunal tube was dislodged into the stomach, resolved after placement back in the jejunum. Three patients who became asymptomatic and normalized amylase on TEN flared upon advancing to diet by mouth. CONCLUSIONS: TEN for acute pancreatitis is as safe and effective, but is significantly less costly than TPN. Compared with TPN, TEN may promote more rapid resolution of the toxicity and stress response to pancreatitis. TEN via jejunal feeding should be used preferentially in this disease setting.

Are patients fed appropriately according to their caloric requirements?

BACKGROUND: Specific morbidity related to underfeeding and overfeeding necessitates the design of nutrition support regimens that provide calories equal to those required on the basis of energy expenditure. This prospective multicenter trial was designed to determine what percent of patients in long-term acute care facilities receive feeding appropriate to their needs and whether accuracy of feeding has an impact on patient clinical status. METHODS: Patients on mechanical ventilation who were hospitalized at 32 Vencor Hospitals over a 9-week period and who were receiving only enteral nutrition by continuous infusion at a presumed goal rate were evaluated once by indirect calorimetry (IC) while on feeding. Caloric intake over the preceding 24 hours was determined by physician orders and by patient intake/output (I/O) record. Caloric requirements were defined by measured resting energy expenditure (REE) + 10% for activity. Degree of metabolism was defined by the ratio: (measured REE/Harris-Benedict predicted REE) x 100, and the degree of feeding by the ratio: (calories provided/calories required) x 100. RESULTS: IC was performed on 335 patients (mean, 11.2 patients per center; range, 1 to 32), of which 72 were excluded for nonphysiological results or failure to achieve steady state, 21 for receiving parenteral nutrition, and 29 for not being on mechanical ventilation at time of testing. The 213 study patients were 58.7% male with mean age 70.1 years (range, 20 to 90 years). Measured REE was <25 kcal/kg in 66.2% of patients and 25 to 35 kcal/kg in 28.6%. Barely half (48.4%) of this patient population was hypermetabolic. Based on physician orders, the majority of patients (58.2%) were overfed, receiving >110% of required calories, and 12.2% were underfed, receiving <90% of requirements. Discrepancies based on I/O records, however, suggested that 36.1% of patients received <90% of those calories ordered. By either basis, only about 25% of patients received feeding within 10% of required calories. The percent of patients being overfed varied between centers, ranging from 32.2% to 92.8%, and was not affected by years of facility IC experience or volume of IC studies per month. The pattern of caloric provision as measured by degree of feeding correlated inversely to degree of metabolism (p < .0001, R2 = .24). Accuracy of feeding had an impact on ventilatory status, as degree of feeding correlated inversely with minute ventilation (p = .001, R2 = .05). Degree of overfeeding also led to significant increases in azotemia (p = .033, R2 = .02). Extrapolating study data over 1 year, reduction in excess volume of enteral formula would have resulted in a cost savings of up to $1.3 million for the Vencor system. CONCLUSIONS: Because energy expenditure is difficult to predict on the basis of conventional equations, patients in long-term acute care facilities routinely are overfed and underfed, with only 25% receiving calories within 10% of required needs. Measuring a patient's energy requirement at least once by IC is important, because the degree of metabolism predicts how easily a patient will be underfed or overfed. The amount of infused calories should be compared with caloric requirements measured by IC, because the accuracy or degree of underfeeding or overfeeding has an impact on ventilatory status and the likelihood for developing azotemia. Although physician practice or bias may reduce the optimal clinical effect, the use of IC to determine caloric requirements may result in significant cost savings.

Infusion protocol improves delivery of enteral tube feeding in the critical care unit.

BACKGROUND: Numerous factors may impede the delivery of enteral tube feedings (ETF) in the intensive care unit (ICU). We designed a prospective study to determine whether the use of an infusion protocol could improve the delivery of ETF in the ICU. METHODS: In a prior prospective study, we monitored all patients admitted to the medical intensive care unit (MICU) or cardiac care unit (CCU) who were made nil per os and placed on ETF (control group). We found that critically ill patients received only 52% of their goal calories, primarily due to physician underordering (66% of goal), frequent cessations of ETF (22% of the time), and slow advancement (14% at goal by 72 hours). Based on these findings, we developed an ETF protocol that incorporated standardized physician ordering and nursing procedures, rapid advancement, and limited ETF interruption. After extensive educational sessions, the ETF protocol was begun. Again, all patients admitted to the MICU or CCU who were made nil per os and placed on ETF were prospectively followed (protocol group). RESULTS: Thirty-one patients in the protocol group were followed during 312 days of ETF and compared with the control group (44 patients with 339 days of ETF). Despite efforts by the nutritional support team, the infusion protocol was used in only 18 patients (58%). The main reasons for noncompliance with the protocol were physician preference and system failure (ETF order sheet not placed in chart). When used, the infusion protocol improved physician ordering (control 66% of goal volume, noncompliant 68%, compliant 82%, p < .05); delivery of calories (control 52% of goal, noncompliant 55%, compliant 68%, p < .05); and advancement of ETF (control 14% at goal by 72 hours, noncompliant 31%, compliant 56%, p < .05). Although significant reduction in ETF cessation due to nursing care was noted, it represented only a fraction of the total time ETF were stopped. Cessation due to residual volumes, patient tolerance, and procedure continued to be a frequent occurrence and was often avoidable. CONCLUSIONS: An evidence-based infusion protocol improved the delivery of ETF in the ICU, primarily because of better physician ordering and more rapid advancement. The nursing staff rapidly assimilated these changes. However, physicians' reluctance to use the protocol limited its efficacy and will need continued educational efforts.

Use of residual volume as a marker for enteral feeding intolerance: prospective blinded comparison with physical examination and radiographic findings.

High gastric residual volumes (RVs) are a frequent cause for cessation of total enteral nutrition (TEN). This study was designed to determine the RV that indicates intolerance or inadequate gastric emptying and to compare the RV findings in a blinded fashion with those findings obtained on physical examination and radiography. Twenty healthy normal volunteers (HNV), 8 stable patients with gastrostomy tubes (GTP), and 10 critically ill patients (CIP) were evaluated prospectively for 8 hours while receiving TEN. No subjects were clearly intolerant (ie, vomiting, aspiration). Of the total RVs recorded, 13.1% were greater than or equal to 150 mL in the CIP group, whereas only 2.4% of the RVs were greater than or equal to 150 mL in the HNV group. None of the RVs in the GTP group were greater than or equal to 150 mL. Objective scores on physical examination failed to correlate with RV (p = .397), as did objective scores on radiography (p = .742). However, objective scores on physical examination were significantly related to scores on radiography (p = .016). Abnormal physical examination findings were found in 4 out of 11 patients (GTP + CIP) with RVs less than 100 mL and in 6 out of 7 with RVs greater than or equal to 100 mL. Abnormal radiographic results were found in 6 out of 11 patients with RVs less than 100 mL, in 7 out of 7 patients with RVs greater than or equal to 100 mL, and in 4 out of 20 HNVs. There was no difference in RVs obtained from the supine or right lateral decubitus positions.(ABSTRACT TRUNCATED AT 250 WORDS)

Use of indirect calorimetry in clinical nutrition.

The tremendous variability in resting energy expenditure makes efforts to predict caloric requirements difficult. Indirect calorimetry has provided a valuable tool in assessing energy expenditure, evaluating the way in which the body uses nutrient fuel, and designing nutritional regimens that best fit the clinical condition of the patient. The many indirect calorimetric instruments available vary in their application to clinical nutrition. The best metabolic studies are achieved by controlling the testing environment, accounting for the many clinical factors that may affect measurements, and eliminating potential sources for error. Although indirect calorimetry would seem to reduce the likelihood of complications from overfeeding, its greatest effect may be in cost savings by avoiding unnecessary nutritional support and in providing a means for clinical research.

Nutritional support in patients with inflammatory bowel disease.

Total parenteral nutrition with bowel rest has been used as primary therapy to reduce disease activity and achieve remission in patients with inflammatory bowel disease (IBD). However, results are short-lived and similar success can be attained through total enteral nutrition with highly specialized elemental or semielemental formulas. Enteral nutrition costs less than parenteral nutrition, maintains gut integrity, stimulates immunocompetence, and helps to control symptoms and overall disease activity. Increased use of enteral formulas can be expected in the future. The role of diet in management of IBD is currently under scrutiny. No one diet is appropriate for all patients, but restriction of fat, fiber, lactose, or oxalate may be necessary to help alleviate symptoms and minimize the risk of complications.

Total parenteral nutrition. Conquering the complexities.

Delivery of total parenteral nutrition (TPN) is a complex procedure requiring a basic knowledge of nutritional physiology and an understanding of the impact of various disease states on utilization of nutrient substrates. The goals of TPN are to reverse catabolism, promote anabolism, and build structural protein. It is important to infuse an adequate amount of calories and protein but to avoid the stress of overfeeding. Various laboratory values may be monitored to ensure that each of the nutrients administered is being adequately tolerated by the patient. Keeping these principles in mind, primary care physicians can deliver a TPN regimen specifically suited for individual patients and can anticipate and prevent any potential complications.

Pancreatic abscess: analysis of a high risk subgroup.

Over the past ten years, 21 cases of pancreatic abscess were diagnosed at our university teaching hospital. On the basis of the findings from CT scan, sonography, and exploratory laparotomy, five patients were determined to have poorly localized disease and 16 patients were felt to have well localized purulent fluid collection. The five patients with poorly localized disease had an overall mortality rate of 80%, an average of 5.2 Ranson criteria, and 80% required partial pancreatic resection. Of the 16 patients with well localized disease there was a mortality rate of 20%, an average of 3.3 Ranson criteria, and only 6% required resection. All five patients who had pancreatic resection died. These data suggest the following conclusions: 1. Patients with pancreatic abscess which is poorly localized have a greater severity of pancreatitis as indicated by a higher average number of Ranson criteria. 2. Patients with a poorly localized phlegmonous abscess more often require pancreatic resection, which is associated with a higher mortality. 3. The high mortality rate seen with patients with a poorly localized phlegmonous pancreatic slough designates this group as a high risk subset of all pancreatic abscess patients.

Guidelines for nutrition therapy in critical illness: are not they all the same?

In general, clinical guidelines identify, summarize, and evaluate the most current data concerning prevention, diagnosis, prognosis, therapy and cost for a specific patient population. This paper will briefly describe the authors' point of view regarding controversial aspects of adult critical care nutrition therapy guidelines published by preeminent professional societies in the United States (US), Canada, and Europe. The US guidelines were developed by subject matter experts to offer recommendations for specialized nutrition therapy that are supported by review and analysis of the pertinent current literature, other national and international guidelines, and by a blend of expert opinion and clinical practicality. A similar strategy was used to compile all three guideline publications resulting in many areas of common agreement, but disparate substantive recommendations do exist regarding: indirect calorimetry versus predictive equations, prokinetics in the intensive care unit (ICU), arginine use in the ICU, probiotic use in the ICU, and acceptable gastric residual volumes in the ICU patient. All of the guidelines are based on high quality studies in patients with critical illness, but like any other therapeutic modality for an ICU patient, nutritional interventions require a multidisciplinary approach that incorporates institutional best practices, individual patient considerations, and above all, clinical judgment.

Positioning a safe gastric puncture point before percutaneous endoscopic gastrostomy.

To position a safe gastric puncture point prior to the percutaneous endoscopic gastrostomy (PEG) a technique using an abdominal plain film with a gastric insufflation was assessed. After insufflated with 500 ml of air, an abdominal plain film was obtained before PEG in 84 patients. The body of the stomach near the angularis, equidistant from the greater and lesser curves, was defined as the optimal gastric puncture point. The location of the puncture points varied greatly, being situated over the right upper quadrant in 31% of patients, left upper in 59%, right lower in 5% and left lower quadrant in 5% of patients. The marked puncture points on abdominal film in some patients were shown to be partially covered by colon or small bowel loop, lie high under the costal margin, or low beneath the umbilicus. An abdominal plain film utilising a gastric insufflation technique prior to PEG may help to determine optimal gastric puncture site selection. Use this technique in clinical practice might hasten procedural time, provide better assurance to the clinical doctor, and provide an added margin of safety for the patient.

Esophageal injection sclerosis.

Hemorrhage from esophageal varices is a serious complication of portal hypertension and cirrhosis, as evidenced by a 50-60% mortality rate and a 40-60% rate of recurrent hemorrhage. Esophageal injection sclerosis (EIS) has emerged as the preferred mode of therapy for esophageal hemorrhage and in most respects is superior to surgical portacaval shunt and medical therapy. EIS controls variceal bleeding acutely in 85-95% of cases and results in the long-term obliteration of varices in 60-80% of patients. EIS decreases the time the patient spends in the hospital, reduces the amount of blood transfused, and may prolong the patient's survival. Complications of ulceration and stenosis can be minimized by proper choice of agent and by manipulating the volume and concentration of sclerosing agent, the interval between sessions, and the pattern of injections within the esophagus. EIS is both effective and reasonably safe for the acute and long-term management of esophageal variceal hemorrhage and can easily be performed at most medical centers in this country.