The provision of adequate nutritional support appears to be essential for critically ill patients and other groups of patients at high risk for having malnutrition. In this review paper we describe our recent research regarding the amount of energy to be provided, how this should be assessed, and the beneficial effects of specialized nutritional support. We have shown that repeated measurements of energy expenditure using indirect calorimetry capture the dynamic energy changes characteristic of hospitalized patients. The provision of energy according to these measurements was associated with lower hospital mortality in critically ill patients when compared to patients receiving a fixed energy intake. A similar study performed in geriatric patients revealed a significant reduction in the number of infections when energy was provided according to repeated measurements. We have also shown that a diet enriched with eicosapentaenoic acid and gamma-linolenic acid improved oxygenation and lung dynamics and decreased ventilation duration in ICU patients with acute lung injury and ARDS. A similarly enriched diet together with micronutrients resulted in significantly less progression of existing pressure ulcers in ICU patients compared to an isonitrogenous, nutrient-sufficient formula. This may be related to an increase in the percentage of positive lymphocyte and granulocyte adhesion molecules.
Guidelines have recommended the provision of adequate nutritional support for hospitalized patients, both for critically ill patients in the intensive care unit (ICU) and for other groups of patients at high risk for having malnutrition, either preexisting at admission or developing during their hospital stay. For ICU patients, it is recommended that nutrition should be provided early after admission to the hospital, ideally within the first 24 h, and preferably by the enteral route where this is possible [
In this review paper, we will describe our recent research in this area, specifically the beneficial effects of optimizing energy requirements to be delivered to both ICU patients and another population at risk for undernutrition, namely, elderly patients undergoing hip replacement. In addition, we will describe the beneficial effects of specialized nutrition on pulmonary function and pressure ulcer development and progression in critically ill patients.
Critically ill patients frequently incur an energy debt. Factors contributing to this include the absence of feeding protocols, physical factors interfering with nutritional delivery such as impaired gastric motility, and frequent interruptions due to the presence of diarrhea or the performance of procedures, such as surgery or radiological examinations [
In the first study, a prospective randomized trial [
A summary of energy and protein parameters during the study period in the perprotocol analysis is shown in Table
Severe lung injury study: summary of energy and protein parameters during the study period and primary outcome in the per protocol analysis.
Parameter | Study group ( |
Control group ( |
|
---|---|---|---|
Mean REE (kcal/day) | 1.976 ± 468 | 1.838 ± 468 | 0.6 |
Mean energy delivered/day (kcal/day) | 2,086 ± 460 | 1,480 ± 356 | 0.01 |
Mean enterally delivered energy/day (kcal/day) | 1,515 ± 756 | 1,316 ± 456 | 0.09 |
Mean delivered parenteral nutrition delivered/day (kcal/day) | 571 ± 754 | 164 ± 294 | 0.001 |
Mean protein delivered/day (g/day) | 76 ± 16 | 53 ± 16 | 0.001 |
Mean daily energy balance (kcal) | 186 ± 206 | −312 ± 481 | 0.001 |
Cumulative energy balance (kcal) | 2,008 ± 2,177 | −3,550 ± 4,591 | 0.01 |
Maximum negative energy balance (kcal) | 15.7 ± 883 | −3,895 ± 4,144 | 0.01 |
Daily mean blood glucose (mg/dl) | 119.6 ± 21.8 | 127.3 ± 33.7 | 0.82 |
Hospital mortality (%) | 28.5 | 48.2 | 0.023 |
Severe lung injury study: outcome measures in the intention to treat analysis.
Parameter | Study group ( |
Control group ( |
|
---|---|---|---|
SOFA score at 3 days | 5.44 ± 2.76 | 7.04 ± 4.25 | 0.027 |
ICU mortality (%) | 24.6 | 26.2 | 0.64 |
Hospital mortality (%) | 32.3 | 47.7 | 0.058 |
Sixty-day survival (%) | 57.9 ± 9.9 | 48.1 ± 7.6 | 0.023 |
Length of ventilation (days) | 16.1 ± 14.7 | 10.5 ± 8.3 | 0.03 |
Length of ICU stay (days) | 17.2 ± 14.6 | 11.7 ± 8.4 | 0.04 |
Infectious complication ( |
37 | 20 | 0.05 |
VAP ( |
18 | 9 | 0.08 |
VAP: ventilator-associated pneumonia; SOFA: sequential organ failure assessment.
Hip fractures remain a significant health risk in the elderly population in Western society. Thus, in the United States, the mean annual number of hip fractures in 2005 was 957.3 per 100 000 for women and 414.4 for men [
One of the factors which might influence the outcome of these patients is their nutritional status. In this regard, up to half of elderly patients with hip fractures are already malnourished on admission to hospital and protein energy malnutrition appears to be more common in older patients with hip fractures than age-matched controls [
We undertook a study to evaluate whether nutritional support guided by repeated measurements of REE improved outcomes in geriatric patients following surgery for hip fractures and compared this to usual nutritional therapy [
Our results are shown in Table
Nutritional and outcome results of geriatric patients following hip fractures.
Parameter | Study group ( |
Control group ( |
|
---|---|---|---|
Well nourished, % | 63.6 | 64.3 | 0.597 |
At risk of malnutrition, % | 36.4 | 35.7 | 0.632 |
Mean energy delivered/day (kcal) | 1121.3 ± 299.1 | 777.1 ± 301.2 | 0.001 |
Cumulative energy balance (kcal) | −1229.9 ± 1763 |
|
0.001 |
Total complications rate, % | 27.3 | 64.3 | 0.012 |
Infectious complications | 13.6 | 50 | 0.008 |
Duration of hospitalization, days | 10.1 ± 3.2 | 12.5 ± 5.5 | 0.061 |
Mortality, |
0 | 2 | 1.0 |
It should be stressed that the improved energy delivery in the intervention group was a function of the intensity of the nutritional intervention generated by the defined and dynamic energy goal. Thus, it was possible to achieve near-target energy intakes by repeated measures of REE under the close supervision of the study dietician. This should be compared to the control group where patients receiving usual care and not under active supervision of a dietician incurred a significant negative energy balance. The importance of a proactive approach with the appropriate staff dedicated to the delivery of adequate nutrition cannot be stressed enough. This study adds further support to the importance of an adequate nutritional intervention in this often malnourished and frail population at risk for significant postoperative complications.
Acute lung injury (ALI) is an abrupt pathologic process in the lungs, often seen as part of a persistent systemic syndrome of inflammation. It is characterized by increased permeability in the lung unexplained by pulmonary capillary hypertension and by hypoxemia resistant to oxygen therapy regardless of the positive end-expiratory pressure (PEEP) [
Dietary fish oil containing eicosapentaenoic acid (EPA) and gamma-linolenic acid (GLA) may modulate proinflammatory eicosanoid and prostaglandin E1 production. Indeed, rats fed a diet enriched with EPA and GLA showed both reduced lung microvascular protein permeability after endotoxin administration and improved oxygenation [
In a prospective randomized study, we examined the effects of an enteral diet enriched with EPA, GLA, and antioxidants (EPA + GLA diet) in patients with ALI/ARDS hospitalized in the ICU [
The results are shown in Table
Outcome results in ventilated patients with acute lung injury receiving a control formula or enteral diet enriched with eicosapentaenoic acid and gamma-linolenic acid.
Parameter | Study group ( |
Control group ( |
|
---|---|---|---|
PaO2/FiO2 ratio | |||
Day 4 | 317.3 ± 99.5 | 214.3 ± 56.4 | 0.05 |
Day 7 | 296.5 ± 165.3 | 236.3 ± 79.8 | 0.05 |
Static compliance (mL/mbar) | |||
Change from day 1 to day 7 | +5.1 | −9 | <0.05 |
Airway resistance (mbar/L/sec) | |||
Change from day 1 to day 7 | −3 | +7 | <0.05 |
Duration of ventilation (hours) at day 7 | 160.4 ± 15.2 | 166.8 ± 5.2 | <0.03 |
We concluded from our study that a diet enriched with EPA + GLA improved oxygenation and lung dynamics and also morbidity related to the lung condition, decreasing the LOV in the ICU. The effects of EPA and GLA in ALI may be related to the modulation of arachidonic acid metabolism, which enhances the production of more anti-inflammatory eicosanoids. These changes may interfere with the alveolar membrane and neutrophil stimulation of mediators and with prostaglandin synthesis.
Critical illness confers susceptibility to the development and persistence of pressure ulcers.
This may be related to several risk factors, including infusions of norepinephrine, scores greater than 13 on the Acute Physiology and Chronic Health Evaluation II, frequent fecal incontinence, anemia, and prolonged ICU stay. In addition, immobility, disturbed sensory perception, 4 and malnutrition, which hampers immune function and wound healing, also increase the risk for pressure ulcers [
Wound healing is a complex, multistage process by which tissue integrity is restored following injury or infection. The process comprises a series of events, including a coagulation phase, an inflammatory phase, and a final repair phase [
In a randomized prospective study of 40 critically ill patients in the ICU, we assessed the impact of fish oil- and micronutrient-enriched formula on the expression of adhesion molecules on peripheral blood leucocytes and correlated this with the healing of pressure ulcers in critically ill patients [
The percentage of positive adhesion molecules was measured by flow cytometric analysis, while the diagnosis of pressure ulcers both before enrolment and during the ICU stay was assessed by the Pressure Ulcer Scale for Healing tool score, a noninvasive clinical aid that attributes a severity score to a pressure ulcer [
Our results (Table
Effect of nutritional supplementation on pressure ulcer healing and adhesion molecules.
Parameter | Study group | Control group |
|
---|---|---|---|
CD18 lymphocytes- (%-) baseline to day 7 of study | 24.4 ± 27.4 to 45.2 ± 33.2 | 48.1 ± 38.1 to 33.1 ± 24.1 | <0.05 |
|
|||
CD11a lymphocytes- (%-) baseline to day 7 of study | 54.4 ± 40.3 to 70.8 ± 39 | 61 ± 43 to 68.7 ± 35.6 | <0.05 |
|
|||
CD49b lymphocytes- (%-) baseline to day 7 of study | 48.7 ± 45.7 to 83.3 ± 34.4 | 47.3 ± 46.8 to 39.1 ± 42.1 | <0.05 |
|
|||
PUSH tool total score-baseline to day 7 of study | 9.25 to 10.75 | 9.10 to 8.79 | <0.05 |
PUSH: pressure ulcer scale for healing.
The results of this study appear to support the positive effect of PUFA on CAM expression in ICU patients. However, the study was limited by the fact that only circulating markers were measured. Immune cells in tissue and plasma do not necessarily reflect the same phenotype and may have differing responsiveness. However, it appears that nutritional support in general may play an important role in the treatment of wound healing and pressure ulcers and specific nutrients may further modulate the efficacy of nutrition. Our findings suggest that n-3-LC-PUFA may have a positive effect on wound healing and that this effect may be mediated by adhesion-dependent mechanisms. We believe that our findings are novel and expand the therapeutic repertoire of fish oil in the critically ill.
In conclusion, we have presented our recent research in the field of nutrition in hospitalized elderly patients and in the critically ill. The main points which have become evident from this research include the following. Energy requirements are most accurately measured by indirect calorimetry. Repeated measurements show that energy demands are dynamic and change over the ICU or hospital stay. Providing adequate energy according to these measurements appears to have a beneficial effect on many outcome parameters. An integral component of our research has been the provision of nutrition as early in the ICU course as possible (preferably within the first 48 hours). In a recent meta-analysis, evaluation of clinical trials commencing enteral nutrition within 48 h of intensive care unit admission revealed a significant reduction in infectious complications [ Adequate provision of nutrition is achievable only when there is a dedicated nutrition team and the appropriate equipment and training. The addition of specialized nutritional support in the form of EPA + GLA may have additional outcome benefits for some patients with ALI/ARDS and aid in the healing and prevention of pressure sores.
Our research in the field of nutrition in the critically ill patient has been extended to involve an international study on the value of tight calorie control, an issue which remains controversial for many ICU practitioners. In addition, we are testing the benefit of specialized nutritional support, especially the use of omega-3-fatty acids, in a variety of clinical conditions including multitrauma, both in the acute setting and a possible effect on posttraumatic stress.
The authors declare that there is no conflict of interests regarding the publication of this paper.