Nutritional support of critically ill patients

Inhibitory Effects of Pentobarbital and Phenobarbital on Human Neutrophil Functions

Neutrophils are important components of the immune system which protects the host from bacterial invasion. Phenobarbital and pentobarbital are used to treat seizures/convulsions in critically ill patients who are sometimes immunocompromised hosts. In the current study we examined the effect of pentobarbital and phenobarbital at clinically relevant concentrations and at 10 and 100 times these concentrations on several aspects of human neutrophil functions using ex vivo system. The two barbiturates impaired neutrophil chemotaxis but failed to suppress phagocytosis. Pentobarbital and phenobarbital also inhibited production of superoxide (O2), hydrogen peroxide (H2O2), and hydroxyl radical (OH·) by neutrophils in a dose-dependent manner. These drugs did not scavenge the reactive oxygen species (ROS) generated by the xanthine-xanthine oxidase system. Elevation of intracellular calcium concentrations ([Ca2+]i) in neutrophils by a stimulant was dose-dependently attenuated with pentobarbital and phenobarbital. The two anesthetics also decreased protein kinase C (PKC) activity. These effects on [Ca2+]i and PKC activity may represent a part of mechanisms responsible for inhibition of neutrophil functions. Further studies using in vivo systems are required to elucidate inhibitory effects of pentobarbital or phenobarbital on ROS production and chemotaxis in clinical settings.

Management of Parenteral Nutrition in Hospitalized Adult Patients [Formula: see text]

Despite the high prevalence of malnutrition in adult hospitalized patients, surveys continue to report that many clinicians are undertrained in clinical nutrition, making targeted nutrition education for clinicians essential for best patient care. Clinical practice models also continue to evolve, with more disciplines prescribing parenteral nutrition (PN) or managing the cases of patients who are receiving it, further adding to the need for proficiency in general PN skills. This tutorial focuses on the daily management of adult hospitalized patients already receiving PN and reviews the following topics: (1) PN basics, including the determination of energy and volume requirements; (2) PN macronutrient content (protein, dextrose, and intravenous fat emulsion); (3) PN micronutrient content (electrolytes, minerals, vitamins, and trace elements); (4) alteration of PN for special situations, such as obesity, hyperglycemia, hypertriglyceridemia, refeeding, and hepatic/renal disease; (5) daily monitoring and adjustment of PN formula; and (6) PN-related complications (PN-associated liver disease and catheter-related complications).

The effects of sedation on gastric emptying and intra-gastric meal distribution in critical illness

OBJECTIVE

To evaluate the effects of sedation with morphine and midazolam (M&M) versus propofol on gastric emptying in critically ill patients.

DESIGN

Descriptive study.

SETTING

Mixed medical and surgical intensive care unit.

PATIENTS

Thirty-six unselected, mechanically ventilated, critically ill patients.

INTERVENTIONS

Gastric scintigraphic data were analysed retrospectively according to whether patients were receiving M&M (n=20; 14M, 6F) or propofol (n=16; 7M, 9F). Measurements were performed over 4 h after administration of 100 ml of Ensure, labelled with 20 MBq Tc99m.

MEASUREMENTS AND RESULTS

Gastric half-emptying time (t1/2) and total and regional (proximal and distal stomach) meal retention (%) were assessed. The median t1/2 of patients receiving M&M (153 (IQR: 72-434) min) was significantly longer than that of patients receiving propofol (58 (34-166) min, p=0.02). Total gastric retention was greater in patients receiving M&M compared to those receiving propofol (p<0.01). Proximal (p=0.02) but not distal (p=0.80) gastric retention was greater in patients who received M&M. Patients who received M&M were more likely to have >or=5% meal retention at 240 min than those treated with propofol (95% (19/20) vs. 56% (9/16); p=0.01). Changes in blood glucose concentrations during the study were similar in the two groups.

CONCLUSIONS

In critical illness, patients receiving M&M for sedation are more likely to have slow gastric emptying, and proximal meal retention than those receiving propofol. The apparent beneficial effects of propofol-based sedation need confirmation by a prospective randomised controlled study.

Standardized concept for the treatment of gastrointestinal dysmotility in critically ill patients--current status and future options

Inhibition of gastrointestinal motility is a major problem in critically ill patients. Motor stasis gives rise to subsequent complications including intolerance to enteral feeding, enhanced permeability of the atrophic intestinal mucosa and conditions as severe as systemic inflammatory response syndrome, sepsis and multiple organ failure. Although the diagnosis of motility disturbances in critically ill patients is difficult, the type and site of the disturbance are important to consider in the analysis of the condition and in the choice of therapeutic approach. The pharmacological treatment of impaired gastrointestinal motility is difficult to handle for the clinician, because the underlying mechanisms are complex and not fully understood and the availability of pharmacological treatment options is limited. In addition, there is a lack of controlled studies on which to build an evidence-based treatment concept for critically ill patients. Notwithstanding this situation, there has been remarkable progress in the understanding of the integrated regulation of gastrointestinal motility in health and disease. These advances, which largely relate to the organization of the enteric nervous system and its signaling mechanisms, enable the intensivist to develop a standardized concept for the use of prokinetic agents in the treatment of impaired gastrointestinal motility in critically ill patients.

Energy expenditure in hospitalized patients: implications for nutritional support

An understanding of energy expenditure in hospitalized patients is necessary to determine optimal energy supply in the care of individuals who require nutritional support. A review was conducted of 19 studies in which resting energy expenditure (REE) had been measured using indirect calorimetry and compared with estimated basal energy expenditure (BEE) from the Harris-Benedict equation. Studies of patients with burns, head injuries, and fever were excluded because REE is known to be increased in these conditions. The studies reported data on 1256 patients with the following diagnoses: postoperative (28%), trauma or sepsis (26%), cancer (18%), pulmonary disease (9%), cardiovascular disease (2%), miscellaneous (9%), and unspecified (6%). The average REE in the 19 studies was 113% of the BEE. The mean +/- SD REE/BEE ratio was higher in 11 studies in which the REE was measured during feeding than in 5 studies in which the measurement was made during fasting (117% +/- 3% vs 105% +/- 4%; P = .047). In those 11 studies, overfeeding may have contributed to higher REE values than otherwise would have been observed. Some evidence indicated that the REE/BEE ratio is higher in more severe illness, but results were inconsistent. Unfortunately, little information is available concerning total energy expenditure, which includes the contribution of physical activity. It appears that most patients can be fed adequately with energy equal to 100% to 120% of estimated BEE. Hypoenergetic feeding may be appropriate in some overweight and obese individuals. Additional research in hospitalized patients on total energy expenditure and on the relationship between severity of illness and energy expenditure is needed.

Glycemic control and nutrition in the intensive care unit

PURPOSE OF REVIEW

Hospital clinicians frequently encounter hyperglycemia due to diabetes or the stress of critical illness in patients who are receiving nutrition support.

RECENT FINDINGS

A growing body of evidence suggests that hyperglycemia in the hospital is associated with adverse outcomes (e.g. disability after acute cardiovascular events, infection and death) and that improvement in outcomes can be achieved with improved glycemic control or insulin. Therefore, familiarity with the implications of hyperglycemia and with its treatment are essential for clinicians practicing in hospital settings.

SUMMARY

Questions persist regarding the optimal glucose goal range in differing patient groups. In addition, while the technology to deliver glycemic control in intensive care unit settings is widely available, data are limited about effective and safe insulin infusions. Research should focus on the risks and benefits of providing nutrition support in this group of patients, optimal glucose goal ranges, and on methods of achieving desired glucose goal ranges.

Stimulation of small intestinal burst activity in the postprandial state differentially affects lipid and glucose absorption in healthy adult humans

Small intestinal motor activity is important for the optimal digestion and absorption of nutrients. These motor responses to feeding are frequently abnormal during critical illness, with the persistence of migrating bursts of contractions during enteral feeding. Whether this disturbance influences nutrient absorption is not known. In this study, the effects of small intestinal burst activity on lipid and glucose absorption were evaluated in 10 healthy human adults (6 males, 4 females, 19-47 yr). Upper gastrointestinal manometry was recorded for 6 h during and shortly after a 20-min intravenous infusion of either erythromycin (1 mg/kg), to stimulate burst activity, or saline (0.9%) in a double-blind randomized fashion. Simultaneously with the start of the intravenous infusion, 60 ml liquid feed mixed with 200 microl 13C-triolein and 2 g 3-O-methylglucose (3-OMG) was infused intraduodenally for 30 min. Absorption of lipid and glucose was assessed using the [13C]triolein breath test and plasma concentrations of 3-OMG, respectively. Infusion of erythromycin was followed by a more rapid onset of burst activity following commencement of the duodenal infusion compared with saline (30 +/- 6.1 vs. 58 +/- 10.7 min; P < 0.05). Erythromycin was associated with a slower recovery of 13CO2 (P < 0.01). A positive correlation existed between the time to onset of burst activity and 13CO2 recovery (P < 0.001). Erythromycin had no effect on 3-OMG absorption. In conclusion, stimulation of small intestinal burst activity reduces the rate of lipid absorption but not glucose absorption in healthy human adults.

Parenteral feeding in a patient with hypertriglyceridemia and increased liver enzyme levels

OBJECTIVE

To discuss nutritional support in a patient with hypertriglyceridemia and liver dysfunction.

METHODS

We describe the hospital course of a critically ill patient with hepatic dysfunction and hypertriglyceridemia who required nutritional support, and we provide an overview of lipid metabolism.

RESULTS

A 27-year-old man with hepatic dysfunction and hypertriglyceridemia, who had undergone kidney transplantation 4 months previously, was admitted to the intensive-care unit with upper gastrointestinal bleeding. He was unable to tolerate enteral feeding, and central parenteral nutrition was initiated. Calories from dextrose and fat were limited because of the presence of increased liver enzyme levels and hypertriglyceridemia. A modified regimen of parenteral nutrition was developed for the patient. The short-term reduction of total calories to 75% of the predicted need is safe.

CONCLUSION

Nutritional support in patients with liver dysfunction and hypertriglyceridemia is complicated and may require temporary underfeeding because of the need to limit fat and dextrose intake.

Immunomodulation of experimental colitis via caloric restriction: role of Nk1.1+ T cells

Inflammatory bowel diseases are immune-mediated disorders. Dietary restriction and NK1.1+ liver-associated lymphocytes (LAL) are considered to be involved in immunomodulation of autoimmune diseases. Our aim was to evaluate the effect of caloric restriction on experimental colitis and to determine NK1.1+ LAL function in immunoregulation. Experimental colitis was induced in C57 black mice by intracolonic instillation of trinitrobenzene sulfonic acid. Caloric restriction to 60% of the daily requirement was started 2 weeks prior to, or simultaneously with, colitis induction and continued throughout the study. Control mice were fed ad libitum. Colitis was assessed by standard clinical and macroscopic scores. To determine the mechanism involved in immunomodulation, liver lymphocytes were isolated and analyzed for NK1.1+ T-cell markers by FACS. T-cell function was evaluated by T-cell proliferation. Serum cytokines were measured by ELISA. Dietary restriction to 60% markedly ameliorated experimental colitis in both groups. These mice gained weight and showed improved macroscopic parameters of colitis. NK1.1+ LAL numbers increased fourfold and NKT cytotoxicity twofold in caloric-restricted mice. The antigen-specific T-cell proliferation index decreased (from 4.45 in controls to 1.15), and IFN-gamma and IL-12 serum levels decreased (from 290 to 200 pg and from 122 to 53 pg, respectively) in caloric-restricted mice. Our conclusion was that dietary restriction induced immunomodulation of experimental colitis and ameliorated the disease. This effect was mediated via an increase in NK1.1+ T lymphocytes, which may play a critical role in keeping the T-cell balance in immunoregulation.

Measured versus estimated energy expenditure in mechanically ventilated critically ill patients

Accurate determination of energy expenditure is essential in patients receiving nutritional support to meet metabolic needs. The purpose of this study was to assess and compare the energy expenditure as measured by indirect calorimetry (MEE) and estimated by 5 equations in the mechanically ventilated critically ill patients. Forty-six patients were divided into either enteral nutrition (EN) (n=l2), total parenteral nutrition (TPN) (n=16) or combined (EN plus TPN) (n=l8) groups. Patients' energy expenditure was measured by indirect calorimetry on two occasions. Anthropometric and biochemical measurements, energy expenditure and medical status (APACHE II score) were also assessed in the intensive care unit (ICU) of Taichung Veteran General hospital. No significant difference was found in the MEE among the 3 groups. The type of nutritional support did not affect MEE. Energy expenditure calculated by using Harris- Benedict, Kleiber and Liu equations times the estimated stress factor did not significantly different than the values of MEE in all groups. There were significant correlations (P<0.01) between MEE and patients' sex (r=-0.499), age (r=-0.402), height (r=0.533), knee height (r=0.431), current body weight (r=0.379), usual body weight (r=0.407), ideal body weight (r=0.466) and urinary urea nitrogen (r=0.383) in the pooled group. Results demonstrated that energy expenditure could be estimated in most critically ill patients by using Harris-Benedict, Kleiber and Liu equations if the estimated stress factor is in the reasonable value.

Effects of whey protein and resistance exercise on body cell mass, muscle strength, and quality of life in women with HIV

OBJECTIVE

To determine the effects of whey protein, resistance exercise, and combined protein and exercise treatment on body cell mass (BCM), muscle strength, and quality of life (QOL) in HIV-infected women with reduced BCM.

DESIGN AND SETTING

Prospective, randomized, controlled trial at a university hospital in New York City.

METHODS

A volunteer sample of 30 HIV-infected women were randomized to whey protein (PRO), progressive resistance exercise (PRE), or combined treatment (PRO-PRE) for 14 weeks after a 6-week control period. The main outcome measures were body weight, BCM, skeletal muscle, fat mass, muscle strength, and QOL.

RESULTS

There were no significant changes in BCM, strength, or QOL during the control period. PRO patients gained 3.6 kg (P = 0.001), and 2.5 kg fat (P = 0.002) with no change in BCM (0.5 kg; P = 0.07) or skeletal muscle (0.6 kg; P = 0.12). The PRE group increased BCM (0.74 kg;P = 0.03) and skeletal muscle (1.2 kg; P < 0.001) and decreased fat (1.7 kg; P = 0.02). PRO-PRE increased BCM (0.61 kg; P = 0.01) without change in skeletal muscle (0.6 kg; P = 0.30). Strength increased for both exercise groups (range, 40.6-95.3%; P < 0.001). The QOL physical activity score improved for PRE (P = 0.02) and worsened for PRO (P = 0.01).

CONCLUSIONS

Resistance exercise significantly increased BCM, muscle mass, muscle strength, and QOL in HIV-infected women with reduced BCM. Whey protein had little effect on BCM accrual. Combined protein and exercise did not increase BCM in excess of gains achieved by exercise alone.

Delayed gastric emptying in ventilated critically ill patients: measurement by 13 C-octanoic acid breath test

OBJECTIVE

To measure gastric emptying in ventilated critically ill patients with a new noninvasive breath test.

DESIGN

Single-center, open study.

SETTING

Combined medical and surgical intensive care unit of a university hospital.

SUBJECTS

Thirty unselected mechanically ventilated critically ill patients receiving gastric feeding and 22 healthy volunteers.

INTERVENTIONS

None.

PATIENTS

After 4 hrs without feeding, intragastric infusion of 100 mL of a liquid meal (Ensure) labeled with 100 microL 13C-octanoic acid. End-expiratory breath samples were collected into evacuated tubes from the respirator circuit every 5 mins for the first hour, then every 15 mins for 3 hrs. End-expiratory breath samples were also collected from volunteers studied supine after an overnight fast following an identical infusion via a nasogastric tube. Breath 13CO2 was measured with an isotope ratio mass spectrometer.

MEASUREMENTS AND MAIN RESULTS

Performance of the breath test posed no difficulty or interference with patient care. The CO2 level was >1% in 1297/1300 breath samples, indicating satisfactory end-expiratory timing. Data are median and interquartile range. Gastric emptying was slower in patients compared with volunteers: gastric emptying coefficient 2.93 (2.17-3.39) vs. 3.58 (3.18-3.79), p <.001 and gastric half emptying time, derived from the area under the 13CO2 curve, 155 min (130-220) vs. 133 min (120-145), p <.008. Fourteen of the 30 patients had a gastric emptying coefficient <95% of all volunteers and 11 had a gastric half emptying time longer than 95% of all volunteers. The Acute Physiology and Chronic Health Evaluation (APACHE II) score (median 22, range 13-43) either at admission or on the day of the study did not correlate with gastric emptying coefficient.

CONCLUSION

Gastric emptying of a calorie-dense liquid meal is slow in 40% to 45% of unselected mechanically ventilated patients in a combined medical and surgical intensive care unit. The 13C-octanoic acid breath test is a novel and useful bedside technique to measure gastric emptying in these patients.

Impacts and patterns of disturbed gastrointestinal function in critically ill patients

Disordered upper gastrointestinal tract motility occurs frequently in intensive care unit patients and often represents a substantial treatment challenge. In addition to specific complications such as pulmonary aspiration and diarrhea, abnormal gastrointestinal motility is a limiting factor for delivery and success of enteral nutrition. The pathophysiologies involved are incompletely understood because of the difficulties of making measurements of gastrointestinal function in critically ill patients. With the recent development of techniques that overcome some of these difficulties, the prospects are brighter for significant advances in this field.

Use of indirect calorimetry to optimize nutrition support and assess physiologic dead space in the mechanically ventilated ICU patient: a case study approach

Indirect calorimetry (IC) is an accurate method of estimating a patient's energy expenditure, particularly the complex critically ill patient who benefits most from an individualized regimen of nutritional support. This bedside technique measures variables related to gas exchange and replaces assumptions about physiologic stress. When indirect calorimetry data are augmented by an arterial blood gas analysis of carbon dioxide (PaCO2), the dead space to tidal volume ratio (VD/VT) can be determined for an individual patient. These data can be valuable to the healthcare team when checking reasons for weaning failure. A case study approach to a 69-year-old man with acute respiratory distress syndrome and biliary sepsis will demonstrate the utility of this measurement. Attention to precise nutritional support and optimal gas exchange can influence the outcome of critically ill mechanically ventilated patients. This discussion highlights the potential benefits of indirect calorimetry for critical care nurses.

Nutritional status of mechanically ventilated critically ill patients: comparison of different types of nutritional support

Malnutrition is a common problem in hospitalized patients. Early assessment of nutritional status may help in identifying patients for whom nutritional interventions are needed. The purpose of this study was to assess and compare the nutritional status of mechanically ventilated critically ill patients who were receiving nutritional support. Forty-nine patients were divided into either enteral nutrition, total parenteral nutrition or combined (enteral plus total parenteral nutrition) groups. Anthropometric and biochemical measurements, and medical status (APACHE II score) were assessed at the 1st day and 14th day of admission in the intensive care unit (ICU) of Taichung Veteran General Hospital. The length of ventilator dependency was significantly positively correlated with calorie and carbohydrate intake in the pooled group. Patients receiving enteral and combined nutrition showed significantly lower anthropometric measurements at the 14th day after admission. Patients in all groups had abnormal mean biochemical values at the 1st day of admission. Subjects in the combined group showed a significant increase in prealbumin and the Maastricht Index levels after 14 days. Patients in all three groups were malnourished when admitted to the ICU. Patients showed a slightly improvement of nutritional status after receiving nutritional support for 14 days.

Liver dysfunction and parenteral nutritional therapies

Hepatobiliary dysfunction associated with the use of total parenteral nutrition is a commonly recognized phenomenon occurring in up to 90% of patients on long-term therapy. Reasons for these abnormalities, both supported by research as well as theoretical possibilities are explored. Practical guidelines considered useful in documenting, preventing and treating serious hepatic consequences of total parenteral nutrition are discussed. The role of combined liver and small bowel transplantation as treatment for select patients is also reviewed.

Common nutritional issues in pediatric and adult critical care medicine

This article discusses many of the nutritional topics important to the intensivist. Nutritional assessment, substrate immunonutrition, and disease specific issues are presented. Early introduction of enteral feeds and the use of nutritional modulation are emphasized.

Systemic inflammatory response syndrome

BACKGROUND

Localized inflammation is a physiological protective response which is generally tightly controlled by the body at the site of injury. Loss of this local control or an overly activated response results in an exaggerated systemic response which is clinically identified as systemic inflammatory response syndrome (SIRS). Compensatory mechanisms are initiated in concert with SIRS and outcome (resolution, multiple organ dysfunction syndrome or death) is dependent on the balance of SIRS and such compensatory mechanisms. No directed therapies have been successful to date in influencing outcome.

METHOD

This review examines the current spectrum and pathophysiology of SIRS.

RESULTS AND CONCLUSION

Further clinical and basic scientific research is required to develop the global picture of SIRS, its associated family of syndromes and their natural histories.