Cynthia C. Lowen

Poor validity of residual volumes as a marker for risk of aspiration in critically ill patients.

Background and Aims:Elevated residual volumes (RV), considered a marker for the risk of aspiration, are used to regulate the delivery of enteral tube feeding. We designed this prospective study to validate such use. Methods:Critically ill patients undergoing mechanical ventilation in the medical, coronary, or surgical intensive care units in a university-based tertiary care hospital, placed on intragastric enteral tube feeding through nasogastric or percutaneous endoscopic gastrostomy tubes, were included in this study. Patients were fed Probalance (Nestlé USA) to provide 25 kcal/kg per day (to which 109 yellow microscopic beads and 4.5 mL of blue food coloring per 1,500 mL was added). Patients were randomized to one of two groups based on management of RV: cessation of enteral tube feeding for RV >400 mL in study patients or for RV >200 mL in controls. Acute Physiology and Chronic Health Evaluation (APACHE) III, bowel function score, and aspiration risk score were determined. Bedside evaluations were done every 4 hrs for 3 days to measure RV, to detect blue food coloring, to check patient position, and to collect secretions from the trachea and oropharynx. Aspiration/regurgitation events were defined by the detection of yellow color in tracheal/oropharyngeal samples by fluorometry. Analysis was done by analysis of variance, Spearman’s correlation, Student’s t-test, Tukey’s method, and Cochran-Armitage test. Results:Forty patients (mean age, 44.6 yrs; range, 18–88 yrs; 70% male; mean APACHE III score, 40.9 [range, 12–85]) were evaluated (21 on nasogastric, 19 on percutaneous endoscopic gastrostomy feeds) and entered into the study. Based on 1,118 samples (531 oral, 587 tracheal), the mean frequency of regurgitation per patient was 31.3% (range, 0% to 94%), with a mean RV for all regurgitation events of 35.1 mL (range, 0–700 mL). The mean frequency of aspiration per patient was 22.1% (range, 0% to 94%), with a mean RV for all aspiration events of 30.6 mL (range, 0–700 mL). The median RV for both regurgitation and aspiration events was 5 mL. Over a wide range of RV, increasing from 0 mL to >400 mL, the frequency of regurgitation and aspiration did not change appreciably. Aspiration risk and bowel function scores did not correlate with the incidence of aspiration or regurgitation. Blue food coloring was detected on only three of the 1,118 (0.27%) samples. RV was ≤50 mL on 84.1% and >400 mL on 1.4% of bedside evaluations. Sensitivities for detecting aspiration per designated RV were as follows: 400 mL = 1.5%; 300 mL = 2.3%; 200 mL = 3.0%; and 150 mL = 4.5%. Low RV did not assure the absence of events, because the frequency of aspiration was 23.0% when RV was <150 mL. Raising the designated RV for cessation of enteral tube feeding from 200 mL to 400 mL did not increase the risk, because the frequency of aspiration was no different between controls (21.6%) and study patients (22.6%). The frequency of regurgitation was significantly less for patients with percutaneous endoscopic gastrostomy tubes compared with those with nasogastric tubes (20.3% vs. 40.7%, respectively; p = .046). There was no correlation between the incidence of pneumonia and the frequency of regurgitation or aspiration. Conclusions:Blue food coloring should not be used as a clinical monitor. Converting nasogastric tubes to percutaneous endoscopic gastrostomy tubes may be a successful strategy to reduce the risk of aspiration. No appropriate designated RV level to identify aspiration could be derived as a result of poor sensitivity over a wide range of RV. Study results do not support the conventional use of RV as a marker for the risk of aspiration.

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)

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

Clinical use of the respiratory quotient obtained from indirect calorimetry

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 patients 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.

Immunonutrition and enteral hyperalimentation of critically Ill patients

BACKGROUND The respiratory quotient (RQ) obtained from indirect calorimetry (IC), defined by the ratio carbon dioxide production (VCO2)/oxygen consumption (VO2), is affected by extremes of substrate use by the body. Underfeeding, which promotes use of endogenous fat stores, should cause decreases in the RQ, whereas overfeeding, which results in lipogenesis, should cause increases in the RQ. Marked increases in VCO2 (with subsequent increases in RQ) in response to overfeeding may cause respiratory compromise in patients with limited pulmonary reserve. Thus, variation in the RQ in response to the feeding regimen may indicate inappropriate feeding and serve as a marker for patient intolerance. This prospective, multicenter study was designed to determine the clinical use of RQ for monitoring adequacy and tolerance of nutrition support. METHODS Patients in any 1 of 30 long-term acute care Kindred hospitals made nil orally (NPO) and placed on total parenteral or enteral feeding were eligible for this study. Arterial blood gas, serum ketones, 24-hour collection of urine urea nitrogen, and IC measurements were obtained on all. Actual volume of enteral/parenteral feeding infused over the 24 hours before performance of IC was documented. RESULTS A total of 263 patients (mean age, 70.2 years, 57.4% male) were entered in the study. Of the 263 study patients, 88.6% required mechanical ventilation, and 92.0% received enteral tube feeding only. Overall, 41.5% of patients were overfed, receiving >110% of required calories, whereas 34.2% were underfed, receiving <90% of required calories. The ratio of calories provided/required correlated significantly with overall measured RQ (p < .0001; R2 = .16). Correcting for the metabolism of protein by calculating a nonprotein RQ (NPRQ) from a 24-hour urine urea nitrogen did not improve this correlation (p < .0001, R2 = .32). Using a measured NPRQ >1.0 to identify overfeeding had an acceptable specificity of 85.1% but a low sensitivity of 38.5%. Similarly, use of a NPRQ <0.85 to determine underfeeding had a specificity of 72.2% and a sensitivity of 55.8%. Comparing the measured NPRQ with a predicted reference RQ (based on percent infusion of carbohydrate/fat and the Lusk table) did not improve the overall use of RQ. In the majority of patients (67.7%), comparison of the measured NPRQ to the predicted value failed to differentiate appropriate (meeting 100% +/- 10% of requirements) from inappropriate feeding. Deviation of the measured NPRQ from predicted failed to identify factors unrelated to substrate use purported to affect the RQ (such as acid/base disturbances or hyper/hypoventilation). Increasing measured RQ did correlate significantly with increasing respiratory rate (p = .002, R2 = .04) and decreasing tidal volume (p = .002, R2 = .04), suggesting reduced tolerance with development of shallow rapid respirations and ventilatory compromise. CONCLUSIONS Although changes in the overall and nonprotein RQ correlate to percent calories provided/required, low sensitivity and specificity limit its efficacy as an indicator of over- or underfeeding. The RQ should not be used to finely adjust the nutrition support regimen. Elevation of overall measured RQ > or = 1.0 may be associated with reduced tolerance and mild respiratory compromise. The clinical use of RQ is limited to a marker of test validity (to confirm measured RQ values are in physiologic range) and a marker for respiratory tolerance of the nutrition support regimen.

Physician-delivered malnutrition: why do patients receive nothing by mouth or a clear liquid diet in a university hospital setting?

Physicians need to be maximally aggressive in their use of total enteral nutrition (TEN) in the critically ill patient, due to its lower cost, better physiology, and lower complication rate when compared to parenteral therapy. Various components in TEN such as glutamine, arginine, RNA nucleotides, omega-3 fish oils, and fiber, may have important roles in immunonutrition by maintaining gut integrity, stimulating the immune system, and preventing bacterial translocation from the gut. For each patient, the physician must choose the optimal enteral formula for that particular disease or organ failure state to maximize nutrient substrate assimilation and tolerance. Total parenteral nutrition (TPN) should be used only when a true contraindication to enteral feedings exists or as adjunctive therapy when full nutritional requirements cannot be met by TEN alone.

Indirect calorimetry: can this technology impact patient outcome?

BACKGROUND Traditional practices of placing patients nil per os (NPO) or on clear liquid diet (CLD) deter delivery of optimal nutrition care and are not always supported by sound physiologic principles. OBJECTIVE This perspective survey evaluated the incidence of this practice, the reasons for such orders, and the response to intervention by the Multidisciplinary Nutrition Team (MNT). METHODS All patients admitted to University of Louisville Hospital were monitored by MNT dietitians and were candidates for the study if they were placed NPO upon CLD for ≥ 3 days. The MNT determined appropriateness of diet orders. RESULTS Out of 1192 admissions, 22.6% of the patients (n = 262, 61% male, mean age 46.1 years) were found to be NPO or on CLD for ≥ 3 days (mean 5.2 days NPO, 1.04 days CLD), and were entered in the study. Uncertainty regarding the reason for the specific diet order occurred more often when patients were placed on CLD than when made NPO (32.1% vs. 15.0% of cases, respectively, P < 0.05). NPO diet orders were more often deemed appropriate by the MNT than were orders for CLD (58.6% vs. 25.6%, respectively, P < 0.05). Compliance with MNT recommendations was low at 40.0%. CONCLUSIONS Despite an active MNT, 22% of patients were made NPO or placed on CLD for a prolonged period of time. More than a third of diet orders for NPO and two thirds of orders for CLD were inappropriate and poorly justified. Improving the adequacy of nutrition therapy is hampered by noncompliance with MNT recommendations.

Is There a Role for Indirect Calorimetry in Maximizing Patient Outcome from Nutritional Alimentation in the Long-Term Nursing Care Setting?

This review of 23 papers involving indirect calorimetry published over the past 18 months shows how our understanding of the metabolic response to injury has changed, highlights the problems introduced by use of predictive equations and alterations in indirect calorimetry testing protocol, and emphasizes the need to monitor cumulative energy balance by comparing daily caloric intake to energy expenditure.

Targeted Physician Education Positively Affects Delivery of Nutrition Therapy and Patient Outcomes Results of a Prospective Clinical Trial

Background: Patients in a long-term nursing care center (NCC) are at risk for the complications of malnutrition because of altered mental status and reduced mobility. Objective: This prospective study sought to determine the need for accurately measuring energy expenditure by indirect calorimetry (IC) and providing sufficient nutrition support, by evaluating the effect of energy balance on nutrition-related complications in the NCC. Design: Patients residing in one NCC were included in this study if there was evidence of hypoalbuminemia, pressure sores, weight loss, actual/ideal body weight less than 85% or more than 150%, or the need for enteral tube feeding or total parenteral nutrition (TPN). After 4 weeks of initial monitoring, patients were evaluated weekly by IC for 8 weeks. Caloric requirements were defined by the measured resting energy expenditure with 10% to 15% added for an activity factor. Monitors included: daily temperature and stool frequency; weekly calorie count, Norton scale (NS), weight, pressure sore number/stage, and serum prealbumin level; and monthly quality of life measure by Minimum Data Set. Results: Of 110 patients screened, 41 met study criteria but 17 were excluded for reasons of agitation, refusal to participate, discharge from the NCC, or death. Of the 24 patients completing the study, 20.8% were male with a mean age of 77.1 years (range 29 to 104 years) and could be grouped on the basis of energy balance. Group 1 (n = 13) had positive cumulative energy balance for the 8 weeks of the study, 30.8% lost weight, 53.8% showed a slight increase in their risk for pressure sores (as evidenced by decreases in NS score) but only 15.4% developed pressure sores. Group 2 (n = 11) had negative cumulative energy balance for the 8 weeks of the study, 63.6% lost weight (odds ratio [OR] = 0.25; 95%

Nutritional support in patients with inflammatory bowel disease

BACKGROUND Malnutrition is a continuing epidemic among hospitalized patients. We hypothesize that targeted physician education should help reduce caloric deficits and improve patient outcomes. MATERIALS AND METHODS We performed a prospective trial of patients (n = 121) assigned to 1 of 2 trauma groups. The experimental group (EG) received targeted education consisting of strategies to increase delivery of early enteral nutrition. Strategies included early enteral access, avoidance of nil per os (NPO) and clear liquid diets (CLD), volume-based feeding, early resumption of feeds postprocedure, and charting caloric deficits. The control group (CG) did not receive targeted education but was allowed to practice in a standard ad hoc fashion. Both groups were provided with dietitian recommendations on a multidisciplinary nutrition team per standard practice. RESULTS The EG received a higher percentage of measured goal calories (30.1 ± 18.5%, 22.1 ± 23.7%, P = .024) compared with the CG. Mean caloric deficit was not significantly different between groups (-6796 ± 4164 kcal vs -8817 ± 7087 kcal, P = .305). CLD days per patient (0.1 ± 0.5 vs 0.6 ± 0.9), length of stay in the intensive care unit (3.5 ± 5.5 vs 5.2 ± 6.8 days), and duration of mechanical ventilation (1.6 ± 3.7 vs 2.8 ± 5.0 days) were all reduced in the EG compared with the CG (P < .05). EG patients had fewer nosocomial infections (10.6% vs 23.6%) and less organ failure (10.6% vs 18.2%) than did the CG, but these differences did not reach statistical significance. CONCLUSION Implementation of specific educational strategies succeeded in greater delivery of nutrition therapy, which favorably affected patient care and outcomes.