Observed appetite and nutrient intake three months after ICU discharge

Comparison of energy intake in critical illness survivors, general medical patients, and healthy volunteers: A descriptive cohort study

BACKGROUND

Intensive care unit (ICU) survivors have reduced oral intake; it is unknown whether intake and associated barriers are unique to this group.

OBJECTIVE

To quantify energy intake and potential barriers in ICU survivors compared with general medical (GM) patients and healthy volunteers.

DESIGN

A descriptive cohort study in ICU survivors, GM patients, and healthy volunteers. Following an overnight fast, participants consumed a 200 ml test-meal (213 kcal) and 180 min later an ad libitum meal to measure energy intake (primary outcome). Secondary outcomes; taste recognition, nutrition-impacting symptoms, malnutrition, and quality of life (QoL). Data are mean ± SD, median (interquartile range [IQR]) or number [percentage]).

RESULTS

Twelve ICU survivors (57 ± 17 years, BMI: 30 ± 6), eight GM patients (69 ± 19 years, BMI: 30 ± 6), and 25 healthy volunteers (58 ± 27 years, BMI: 25 ± 4) were included. Recruitment ceased early because of slow recruitment and SARS-CoV-2. Energy intake was lower in both patient groups than in health (ICU: 289 [288, 809], GM: 426 [336, 592], health: 815 [654, 1165] kcal). Loss of appetite was most common (ICU: 78%, GM: 67%). For ICU survivors, GM patients and healthy volunteers, respectively, severe malnutrition prevalence; 40%, 14%, and 0%; taste identification; 8.5 [7.0, 11.0], 8.5 [7.0, 9.5], and 8.0 [6.0, 11.0]; and QoL; 60 [40-65], 50 [31-55], and 90 [81-95] out of 100.

CONCLUSIONS

Energy intake at a buffet meal is lower in hospital patients than in healthy volunteers but similar between ICU survivors and GM patients. Appetite loss potentially contributes to reduced energy intake.

Post-intensive care syndrome follow-up system after hospital discharge: a narrative review

BACKGROUND

Post-intensive care syndrome (PICS) is the long-lasting impairment of physical functions, cognitive functions, and mental health after intensive care. Although a long-term follow-up is essential for the successful management of PICS, few reviews have summarized evidence for the efficacy and management of the PICS follow-up system.

MAIN TEXT

The PICS follow-up system includes a PICS follow-up clinic, home visitations, telephone or mail follow-ups, and telemedicine. The first PICS follow-up clinic was established in the U.K. in 1993 and its use spread thereafter. There are currently no consistent findings on the efficacy of PICS follow-up clinics. Under recent evidence and recommendations, attendance at a PICS follow-up clinic needs to start within three months after hospital discharge. A multidisciplinary team approach is important for the treatment of PICS from various aspects of impairments, including the nutritional status. We classified face-to-face and telephone-based assessments for a PICS follow-up from recent recommendations. Recent findings on medications, rehabilitation, and nutrition for the treatment of PICS were summarized.

CONCLUSIONS

This narrative review aimed to summarize the PICS follow-up system after hospital discharge and provide a comprehensive approach for the prevention and treatment of PICS.

Illness Weakness, Polyneuropathy and Myopathy: Diagnosis, treatment, and long-term outcomes

BACKGROUND

Severe weakness associated with critical illness (CIW) is common. This narrative review summarizes the latest scientific insights and proposes a guide for clinicians to optimize the diagnosis and management of the CIW during the various stages of the disease from the ICU to the community stage.

MAIN BODY

CIW arises as diffuse, symmetrical weakness after ICU admission, which is an important differentiating factor from other diseases causing non-symmetrical muscle weakness or paralysis. In patients with adequate cognitive function, CIW can be easily diagnosed at the bedside using manual muscle testing, which should be routinely conducted until ICU discharge. In patients with delirium or coma or those with prolonged, severe weakness, specific neurophysiological investigations and, in selected cases, muscle biopsy are recommended. With these exams, CIW can be differentiated into critical illness polyneuropathy or myopathy, which often coexist. On the general ward, CIW is seen in patients with prolonged previous ICU treatment, or in those developing a new sepsis. Respiratory muscle weakness can cause neuromuscular respiratory failure, which needs prompt recognition and rapid treatment to avoid life-threatening situations. Active rehabilitation should be reassessed and tailored to the new patient's condition to reduce the risk of disease progression. CIW is associated with long-term physical, cognitive and mental impairments, which emphasizes the need for a multidisciplinary model of care. Follow-up clinics for patients surviving critical illness may serve this purpose by providing direct clinical support to patients, managing referrals to other specialists and general practitioners, and serving as a platform for research to describe the natural history of post-intensive care syndrome and to identify new therapeutic interventions. This surveillance should include an assessment of the activities of daily living, mood, and functional mobility. Finally, nutritional status should be longitudinally assessed in all ICU survivors and incorporated into a patient-centered nutritional approach guided by a dietician.

CONCLUSIONS

Early ICU mobilization combined with the best evidence-based ICU practices can effectively reduce short-term weakness. Multi-professional collaborations are needed to guarantee a multi-dimensional evaluation and unitary community care programs for survivors of critical illnesses.

Beta-hydroxy-beta-methylbutyrate supplementation and functional outcomes in multitrauma patients: A pilot randomized controlled trial

BACKGROUND

Beta-hydroxy-beta-methylbutyrate (HMB) is a nutrition supplement that may attenuate muscle wasting from critical illness. This trial aimed to determine feasibility of administering a blinded nutrition supplement in the intensive care unit (ICU) and continuing it after ICU discharge.

METHODS

Single-center, parallel-group, blinded, placebo-controlled, randomized feasibility trial. After traumatic injury necessitating admission to ICU, participants were randomized to receive an enteral study supplement of 3 g of HMB (intervention) or placebo daily for 28 days or until hospital discharge. Primary outcome was feasibility of administering the study supplement, quantified as protocol adherence. Secondary outcomes included change in quadriceps muscle thickness, measured weekly until day 28 or hospital discharge by using ultrasound and analyzed by using a linear mixed model.

RESULTS

Fifty randomized participants (intervention, n = 26; placebo, n = 24) showed comparable baseline characteristics. Participants received 862 (84.3%) of the 1022 prescribed supplements during hospitalization with 543 (62.8%) delivered via an enteral feeding tube. The median (IQR) number of study supplements successfully administered per participant was 19.5 (13.0-24.0) in the intervention group and 16.5 (8.5-23.5) in the placebo group. Marked loss of quadriceps muscle thickness occurred in both groups, with the point estimate favoring attenuated muscle loss with the intervention, albeit with wide CIs (mean intervention difference after 28 days, 0.26 cm [95% CI, -0.13 to 0.64]).

CONCLUSION

A blinded, placebo-controlled, randomized clinical trial of daily enteral HMB supplementation for up to 28 days in hospital is feasible. Any effect of HMB supplementation to attenuate muscle wasting after traumatic injury remains uncertain.

The effect of protein provision and exercise therapy on patient-reported and clinical outcomes in intensive care unit survivors: A systematic review

BACKGROUND

Intensive care unit (ICU) survivors deal with long-term health problems, which negatively affect their quality of life (QoL). Nutritional and exercise intervention could prevent the decline of muscle mass and physical functioning which occurs during critical illness. Despite the growing amount of research, robust evidence is lacking.

METHODS

For this systematic review, Embase, PubMed and Cochrane Central Register of Controlled Trials databases were searched. The effect of protein provision (PP) or combined protein and exercise therapy (CPE) during or after ICU admission on QoL, physical functioning, muscle health, protein/energy intake and mortality was assessed compared to standard care.

RESULTS

Four thousand nine hundred and fifty-seven records were identified. After screening, data were extracted for 15 articles (9 randomised controlled trials and 6 non-randomised studies). Two studies reported improvements in muscle mass, of which one found higher independency in activities of daily living. No significant effect was found on QoL. Overall, protein targets were seldom met and often below recommendations.

CONCLUSION

Evidence for the effect of PP or CPE on patient-reported outcomes in ICU survivors is limited due to study heterogeneity and lack of high-quality studies. Future research and clinical practice should focus on adequate protein delivery with exercise interventions to improve long-term outcomes.

Nutritional issues concerning general medical ward patients: feeding patients recovering from critical illness

PURPOSE OF REVIEW

ICU survivors often spend long periods of time in general wards following transfer from ICU in which they are still nutritionally compromised. This brief review will focus on the feeding of patients recovering from critical illness, as no formal recommendations or guidelines on nutrition management are available for this specific situation.

RECENT FINDINGS

While feeding should start in the ICU, it is important to continue and adapt nutritional plans on the ward to support individuals recovering from critical illness. This process is highly complex - suboptimal feeding may contribute significantly to higher morbidity and mortality, and seriously hinder recovery from illness. Recently, consensus diagnostic criteria for malnutrition have been defined and large-scale trials have advanced our understanding of the pathophysiological pathways underlying malnutrition. They have also helped further develop treatment algorithms. However, we must continue to identify specific clinical parameters and blood biomarkers to further personalize therapy for malnourished patients. Better understanding of such factors may help us adapt nutritional plans more efficiently.

SUMMARY

Adequate nutrition is a vigorous component of treatment in the post-ICU period and can enhance recovery and improve clinical outcome. To better personalize nutritional treatment because not every patient benefits from support in the same manner, it is important to further investigate biomarkers with a possible prognostic value.

Appetite loss and associated factors at 1 year after intensive care unit elder survivors in a secondary analysis of the SMAP-HoPe study

Appetite loss, a common but serious issue in older patients, is an independent risk factor for sarcopenia, which is associated with high mortality. However, few studies have explored the phenomenon of appetite loss after discharge from the intensive care unit (ICU). Therefore, we aimed to describe the prevalence of appetite loss and relationship between appetite loss and depression in patients living at home 12 months after intensive care. This study involved secondary analysis of data obtained from a published ambidirectional study examining post-intensive care syndrome 12 months after discharge (SMAP-HoPe study) conducted in 12 ICUs in Japan. We included patients aged > 65 years. The Short Nutritional Assessment Questionnaire and Hospital Anxiety Depression Scale were used for the analysis. Descriptive statistics and a multilevel generalized linear model were used to clarify the relationship between appetite loss and depression. Data from 468 patients were analyzed. The prevalence of appetite loss was 25.4% (95% confidence interval [CI], 21.5-29.4). High severity of depression was associated with a high probability of appetite loss (odds ratio, 1.2; 95%CI, 1.14-1.28; p = 0.00). Poor appetite is common 12 months after intensive care and is associated with the severity of depression.

Adequacy of Nutritional Intakes during the Year after Critical Illness: An Observational Study in a Post-ICU Follow-Up Clinic

Whether nutritional intakes in critically ill survivors after hospital discharge are adequate is unknown. The aims of this observational study were to describe the energy and protein intakes in ICU survivors attending a follow-up clinic compared to empirical targets and to explore differences in outcomes according to intake adequacy. All adult survivors who attended the follow-up clinic at 1, 3 and 12 months (M1, M3, M12) after a stay in our intensive care unit (ICU) ≥ 7 days were recruited. Average energy and protein intakes over the 7 days before the face-to-face consultation were quantified by a dietician using food anamnesis. Self-reported intakes were compared empirically to targets for healthy people (FAO/WHO/UNU equations), for critically ill patients (25 kcal/kg/day and 1.3 g protein/kg/day). They were also compared to targets that are supposed to fit post-ICU patients (35 kcal/kg/day and 1.5 g protein/kg/day). Blood prealbumin level and handgrip strength were also measured at each timepoint. A total of 206 patients were analyzed (49, 97 and 60 at the M1, M3 and M12, respectively). At M1, M3 and M12, energy intakes were 73.2 [63.3–86.3]%, 79.3 [69.3–89.3]% and 82.7 [70.6–93.7]% of healthy targets (p = 0.074), respectively. Protein intakes were below 0.8 g/kg/day in 18/49 (36.7%), 25/97 (25.8%) and 8/60 (13.3%) of the patients at M1, M3 and M12, respectively (p = 0.018), and the protein intakes were 67.9 [46.5–95.8]%, 68.5 [48.8–99.3]% and 71.7 [44.9–95.1]% of the post-ICU targets (p = 0.138), respectively. Prealbumin concentrations and handgrip strength were similar in patients with either inadequate energy intakes or inadequate protein intakes, respectively. In our post-ICU cohort, up to one year after discharge, energy and protein intakes were below the targets that are supposed to fit ICU survivors in recovery phase.

The role of nutrition rehabilitation in the recovery of survivors of critical illness: underrecognized and underappreciated

Many survivors of critical illness face significant physical and psychological disability following discharge from the intensive care unit (ICU). They are often malnourished, a condition associated with poor outcomes, and nutrition remains problematic particularly in the early phases of ICU recovery. Yet nutrition rehabilitation, the process of restoring or optimizing nutritional status following illness, is seldom prioritized, possibly because it is an underrecognized and underappreciated area in critical care rehabilitation and research. To date, 16 original studies have been published where one of the objectives includes measurement of indices relating to nutritional status (e.g., nutrition intake or factors impacting nutrition intake) in ICU survivors. The primary aim of this narrative review is to provide a comprehensive summary of key themes arising from these studies which form the basis of our current understanding of nutritional recovery and rehabilitation in ICU survivors. ICU survivors face a multitude of barriers in achieving optimal nutrition that are of physiological (e.g., poor appetite and early satiety), functional (e.g., dysphagia, reduced ability to feed independently), and psychological (e.g., low mood, body dysmorphia) origins. Organizational-related barriers such as inappropriate feeding times and meal interruptions frequently impact an ICU survivor’s ability to eat. Healthcare providers working on wards frequently lack knowledge of the specific needs of recovering critically ill patients which can negatively impact post-ICU nutrition care. Unsurprisingly, nutrition intake is largely inadequate following ICU discharge, with the largest deficits occurring in those who have had enteral nutrition prematurely discontinued and rely on an oral diet as their only source of nutrition. With consideration to themes arising from this review, pragmatic strategies to improve nutrition rehabilitation are explored and directions for future research in the field of post-ICU nutrition recovery and rehabilitation are discussed. Given the interplay between nutrition and physical and psychological health, it is imperative that enhancing the nutritional status of an ICU survivor is considered when developing multidisciplinary rehabilitation strategies. It must also be recognized that dietitians are experts in the field of nutrition and should be included in stakeholder meetings that aim to enhance ICU rehabilitation strategies and improve outcomes for survivors of critical illness.

β-Hydroxy-β-methylbutyrate (HMB) supplementation and functional outcomes in multi-trauma patients: a study protocol for a pilot randomised clinical trial (BOOST trial)

Background

There are no therapies proven to diminish the muscle wasting that occurs in patients after major trauma who are admitted to the intensive care unit (ICU). β-Hydroxy-β-methylbutyrate (HMB) is a nutrition intervention that may attenuate muscle loss and, thereby, improve recovery. The primary aim of this study is to determine the feasibility of a blinded randomised clinical trial of HMB supplementation to patients after major trauma who are admitted to the ICU. Secondary aims are to establish estimates for the impact of HMB when compared to placebo on muscle mass and nutrition-related patient outcomes.

Methods

This prospective, single-centre, blinded, randomised, placebo-controlled, parallel-group, feasibility trial with allocation concealment will recruit 50 participants over 18 months. After informed consent, participants will be randomised [1:1] to receive either the intervention (three grams of HMB dissolved in either 150 ml of orange juice for those allowed oral intake or 150 ml of water for those being enterally fed) or placebo (150 ml of orange juice for those allowed oral intake or 150 ml of water for those being enterally fed). The intervention will be commenced in ICU, continued after ICU discharge and ceased at hospital discharge or day 28 post randomisation, whichever occurs first. The primary outcome is the feasibility of administering the intervention. Secondary outcomes include change in muscle thickness using ultrasound and other nutritional and patient-centred outcomes.

Discussion

This study aims to determine the feasibility of administering HMB to critically ill multi-trauma patients throughout ICU admission until hospital discharge. Results will inform design of a larger randomised clinical trial.

Trial registration

The protocol is registered with Australian New Zealand Clinical Trials Registry (ANZCTR) ANZCTR: 12620001305910. UTN: U1111-1259-5534.

Assessment of physiological barriers to nutrition following critical illness

BACKGROUND & AIMS

Nutrition may be important for recovery from critical illness. Gastrointestinal dysfunction is a key barrier to nutrition delivery in the Intensive Care Unit (ICU) and metabolic rate is elevated exacerbating nutritional deficits. Whether these factors persist following ICU discharge is unknown. We assessed whether delayed gastric emptying (GE) and impaired glucose absorption persist post-ICU discharge.

METHODS

A prospective observational study was conducted in mechanically ventilated adults at 3 time-points: in ICU (V1); on the post-ICU ward (V2); and 3-months after ICU discharge (V3); and compared to age-matched healthy volunteers. On each visit, all participants received a test-meal containing 100 ml of 1 kcal/ml liquid nutrient, labelled with 0.1 g ¹³C-octanoic acid and 3 g 3-O-Methyl-glucose (3-OMG), and breath and blood samples were collected over 240min to quantify GE (gastric emptying coefficient (GEC)), and glucose absorption (3-OMG concentration; area under the curve (AUC)). Data are mean ± standard error of the mean (SEM) and differences shown with 95% confidence intervals (95%CI).

RESULTS

Twenty-six critically ill patients completed V1 (M:F 20:6; 62.0 ± 2.9 y; BMI 29.8 ± 1.2 kg/m²; APACHE II 19.7 ± 1.9), 15 completed V2 and eight completed V3; and were compared to 10 healthy volunteers (M:F 6:4; 60.5 ± 7.5 y; BMI 26.0 ± 1.0 kg/m²). GE was significantly slower on V1 compared to health (GEC difference: -0.96 (95%CI -1.61, -0.31); and compared to V2 (-0.73 (-1.16, -0.31) and V3 (-1.03 (-1.47, -0.59). GE at V2 and V3 were not different to that in health (V2: -0.23 (-0.61, 0.14); V3: 0.10 (-0.27, 0.46)). GEC: V1: 2.64 ± 0.19; V2: 3.37 ± 0.12; V3: 3.67 ± 0.10; health: 3.60 ± 0.13. Glucose absorption (3-OMG AUC_0-240) was impaired on V1 compared to V2 (-37.9 (-64.2, -11.6)), and faster on V3 than in health (21.8 (0.14, 43.4) but absorption at V2 and V3 did not differ from health. Intestinal glucose absorption: V1: 63.8 ± 10.4; V2: 101.7 ± 7.0; V3: 111.9 ± 9.7; health: 90.7 ± 3.8.

CONCLUSION

This study suggests that delayed GE and impaired intestinal glucose absorption recovers rapidly post-ICU. This requires further confirmation in a larger population. The REINSTATE trial was prospectively registered at www.anzctr.org.au.

TRIAL ID

ACTRN12618000370202.

Medical nutrition therapy for patients with malnutrition post-intensive care unit discharge: A case report of recovery from coronavirus disease 2019 (COVID-19)

Patients discharged from an intensive care unit (ICU) are frequently malnourished and experience ongoing inadequate nutrition intake because of a variety of barriers, which may lead to further declines in nutrition status. The coronavirus disease 2019 (COVID-19) pandemic has drawn increased awareness to this vulnerable patient population and the importance of nutrition rehabilitation to promote optimal recovery from acute illness. Despite this, there are no formal guidelines addressing medical nutrition therapy during the post-ICU recovery phase. This review provides an overview of the nutrition management of patients during the post-ICU recovery phase with a specific focus on COVID-19. A case study will demonstrate how medical nutrition therapy improved the nutrition status and quality of life for a patient who became severely malnourished after a prolonged hospitalization for COVID-19.

Gut dysfunction in the ICU: diagnosis and management

PURPOSE OF REVIEW

Progress has been made in our understanding of gut dysfunction in critical illness. This review will outline new findings and give perspectives based on previous knowledge and concurrent advances in nutrition.

RECENT FINDINGS

The relationship between gut dysfunction and poor outcomes in critical illness has received considerable interest. It remains uncertain whether gut dysfunction is merely a marker of illness severity or if it is directly responsible for prolonged critical illness and increased mortality. This relationship is difficult to ascertain given there is no agreed method for identification and quantification; biomarkers such as intestinal fatty acid binding protein and citrulline show promise but require further study. Recent studies have investigated strategies to deliver enteral nutrition targets with impacts on gut function, including high calorie or protein formulae, intermittent regimes and novel prokinetics.

SUMMARY

Gut dysfunction is associated with poor outcomes, but it remains uncertain whether strategies to improve gut function will influence survival and recovery.

Prioritizing nutrition during recovery from critical illness

PURPOSE OF REVIEW

Patients admitted to the intensive care unit (ICU) often experience a significant decline in nutritional status due to a combination of the physiologic response to critical illness and insufficient calorie intake. The majority of research related to nutrition interventions for this population focuses on nutrition support during the acute phase. Minimal attention is given to the nutritional status of ICU patients during the recovery phase. This review will describe calorie intake when ICU care ends, provide an overview of barriers that limit intake, and possible interventions to improve nutritional status.

RECENT FINDINGS

Current evidence suggests patients are consuming < 60% of calorie requirements after extubation and ICU discharge. This inadequate calorie intake may exacerbate weight loss and muscle and fat wasting. Physiologic, physical, and cognitive manifestations of critical illness can lead to multiple issues that cause poor intake. Possible interventions to improve calorie intake include a patient-centered approach that utilizes oral nutrition supplements and enteral nutrition.

SUMMARY

Consuming adequate caloric intake in the recovery phase of critical illness is essential for rehabilitation. A systematic, patient centered approach that includes close monitoring of calorie and protein and timely interventions may be the best method to improve overall intake.

Oral Nutrition during and after Critical Illness: SPICES for Quality of Care!

Malnutrition is associated to poor outcomes in critically ill patients. Oral nutrition is the route of feeding in less than half of the patients during the intensive care unit (ICU) stay and in the majority of ICU survivors. There are growing data indicating that insufficient and/or inadequate intakes in macronutrients and micronutrients are prevalent within these populations. The present narrative review focuses on barriers to food intakes and considers the different points that should be addressed in order to optimize oral intakes, both during and after ICU stay. They are gathered in the SPICES concept, which should help ICU teams improve the quality of nutrition care following 5 themes: swallowing disorders screening and management, patient global status overview, involvement of dieticians and nutritionists, clinical evaluation of nutritional intakes and outcomes, and finally, supplementation in macro-or micronutrients.

Nutrition During Critical Care: An Audit on Actual Energy and Protein Intakes

INTRODUCTION

Oral nutrition is delivered frequently in intensive care units (ICUs) but rarely studied. The primary objective of this study was to quantify nutrition intakes in patients exclusively orally fed (OF) and in those receiving medical nutrition solutions or both.

METHODS

Adults who stayed in a mixed ICU for ≥3 days were studied. Nutrition deficits were calculated as the difference between estimated energy or protein targets (determined by weight-based formulas) and actual intakes (recorded on a daily basis by nurses). Total volumes of enteral or parenteral nutrition solutions, propofol, and glucose infused over 24 hours were collected and energy and protein amounts were calculated. In OF patients, food intake at each meal (breakfast, lunch, and dinner) was estimated using the "one-quarter portion" method.

RESULTS

Among the 289 included patients aged 67 (57-75.5) years, 253 were fed and received, on average, 14.3 (7.8-19) kcal/kg/d and 0.53 (0.27-0.8) g/kg/d protein. In OF patients (n = 126), intakes were 9.7 (5.8-19) kcal/kg/d and 0.35 (0.17-0.57) g/kg/d protein. In the subset of OF patients with ICU stay ≥ 7 days (n = 37), respectively, 51% and 94% never received ≥80% of their energy and protein targets.

CONCLUSION

Nutrition intakes were lower by oral feeding compared with other exclusive or combined medical nutrition. Compared with the prescribed amounts, the deficit was larger for proteins than for energy.

Nutrition intake in the post-ICU hospitalization period

PURPOSE OF REVIEW

The care of critically ill patients has evolved over recent years, resulting in significant reductions in mortality in developed countries; sometimes with prolonged issues with recovery. Nutrition research has focused on the early, acute period of critical illness, until more recently, where the post-ICU hospitalization period in critical care survivors has become a focus for nutrition rehabilitation. In this period, nutrition rehabilitation may be a vital component of recovery.

RECENT FINDINGS

Overall, oral nutrition is the most common mode of nutrition provision in the post-ICU period. Compared with oral intake alone, calorie and protein requirements can be better met with the addition of oral supplements and/or enteral nutrition to oral intake. However, calorie and protein intake remains below predicted targets in the post-ICU hospitalization period. Achieving nutrition targets are complex and multifactorial, but can primarily be grouped into three main areas: patient factors; clinician factors; and system factors.

SUMMARY

A nutrition intervention in the post-ICU hospitalization period may provide an opportunity to improve survival and functional recovery. However, there are multiple barriers to the delivery of calculated nutrition requirements in this period, a limited understanding of how this can be improved and how this translates into clinical benefit.