Micronutrient deficiencies in critical illness

BACKGROUND & AIMS

Low micronutrient levels in critical illness have been reported in multiple studies. Because of the antioxidant properties of various micronutrients, micronutrient deficiency may augment oxidative stress in critical illness. However, it remains unclear whether micronutrient concentrations in ICU patients are different from those in healthy age-matched controls. It is also unclear whether micronutrient deficiency develops, worsens, or resolves during ICU admission without supplementation.

METHODS

We prospectively studied a cohort of adult critically ill patients. Micronutrient levels, including selenium, β-carotene, vitamin C, E, B₁ and B₆ were measured repeatedly during the first week of ICU admission. We compared the micronutrient concentrations at ICU admission to those of healthy age-matched controls. In addition, associations between micronutrient concentrations with severity of illness, inflammation and micronutrient intake were investigated.

RESULTS

Micronutrient blood concentrations were obtained from 24 critically ill adults and 21 age-matched healthy controls. The mean micronutrient levels at admission in the ICU patients were: selenium 0.52 μmol/l, β-carotene 0.17 μmol/l, vitamin C 21.5 μmol/l, vitamin E 20.3 μmol/l, vitamin B₁ 129.5 nmol/l and vitamin B₆ 41.0 nmol/l. In the healthy controls micronutrient levels of selenium (0.90 μmol/l), β-carotene (0.50 μmol/l), vitamin C (45 μmol/l) and vitamin E (35.5 μmol/l) were significantly higher, while vitamin B₁ (122 nmol/l) and B₆ (44 nmol/l) were not significantly different between patients and controls. Selenium, vitamin B₁ and vitamin B₆ levels remained stable during ICU admission. Vitamin C levels dropped significantly until day 5 (p < 0.01). Vitamin E and β-carotene levels increased significantly on days 5-7 and day 7, respectively (p < 0.01). Micronutrient levels were not associated with severity of illness, CRP or micronutrient intake during the admission.

CONCLUSIONS

At admission, ICU patients already had lower plasma levels of selenium, β-carotene, vitamin C and vitamin E than healthy controls. Vitamin C levels dropped significantly during the first days of ICU admission, while β-carotene and vitamin E levels increased after 5-7 days. No association between micronutrient levels and severity of illness, C-reactive protein (CRP) or micronutrient intake was found. Progressive enteral tube feeding containing vitamins and trace elements does not normalize plasma levels in the first week of ICU stay. This was a hypothesis generating study and more investigation in a larger more diverse sample is needed.

The effect of cisatracurium infusion on the energy expenditure of critically ill patients: an observational cohort study

Background

Both overfeeding and underfeeding of intensive care unit (ICU) patients are associated with worse outcomes. A reliable estimation of the energy expenditure (EE) of ICU patients may help to avoid these phenomena. Several factors that influence EE have been studied previously. However, the effect of neuromuscular blocking agents on EE, which conceptually would lower EE, has not been extensively investigated.

Methods

We studied a cohort of adult critically ill patients requiring invasive mechanical ventilation and treatment with continuous infusion of cisatracurium for at least 12 h. The study aimed to quantify the effect of cisatracurium infusion on EE (primary endpoint). EE was estimated based on ventilator-derived VCO₂ (EE in kcal/day = VCO₂ × 8.19). A subgroup analysis of septic and non-septic patients was performed. Furthermore, the effects of body temperature and sepsis on EE were evaluated. A secondary endpoint was hypercaloric feeding (> 110% of EE) after cisatracurium infusion.

Results

In total, 122 patients were included. Mean EE before cisatracurium infusion was 1974 kcal/day and 1888 kcal/day after cisatracurium infusion. Multivariable analysis showed a significantly lower EE after cisatracurium infusion (MD − 132.0 kcal (95% CI − 212.0 to − 52.0; p = 0.001) in all patients. This difference was statistically significant in both sepsis and non-sepsis patients (p = 0.036 and p = 0.011). Non-sepsis patients had lower EE than sepsis patients (MD − 120.6 kcal; 95% CI − 200.5 to − 40.8, p = 0.003). Body temperature and EE were positively correlated (Spearman’s rho = 0.486, p < 0.001). Hypercaloric feeding was observed in 7 patients.

Conclusions

Our data suggest that continuous infusion of cisatracurium in mechanically ventilated ICU patients is associated with a significant reduction in EE, although the magnitude of the effect is small. Sepsis and higher body temperature are associated with increased EE. Cisatracurium infusion is associated with overfeeding in only a minority of patients and therefore, in most patients, no reductions in caloric prescription are necessary.

Feeding mitochondria: Potential role of nutritional components to improve critical illness convalescence

Persistent physical impairment is frequently encountered after critical illness. Recent data point towards mitochondrial dysfunction as an important determinant of this phenomenon. This narrative review provides a comprehensive overview of the present knowledge of mitochondrial function during and after critical illness and the role and potential therapeutic applications of specific micronutrients to restore mitochondrial function. Increased lactate levels and decreased mitochondrial ATP-production are common findings during critical illness and considered to be associated with decreased activity of muscle mitochondrial complexes in the electron transfer system. Adequate nutrient levels are essential for mitochondrial function as several specific micronutrients play crucial roles in energy metabolism and ATP-production. We have addressed the role of B vitamins, ascorbic acid, α-tocopherol, selenium, zinc, coenzyme Q10, caffeine, melatonin, carnitine, nitrate, lipoic acid and taurine in mitochondrial function. B vitamins and lipoic acid are essential in the tricarboxylic acid cycle, while selenium, α-tocopherol, Coenzyme Q10, caffeine, and melatonin are suggested to boost the electron transfer system function. Carnitine is essential for fatty acid beta-oxidation. Selenium is involved in mitochondrial biogenesis. Notwithstanding the documented importance of several nutritional components for optimal mitochondrial function, at present, there are no studies providing directions for optimal requirements during or after critical illness although deficiencies of these specific micronutrients involved in mitochondrial metabolism are common. Considering the interplay between these specific micronutrients, future research should pay more attention to their combined supply to provide guidance for use in clinical practise. REVISION NUMBER: YCLNU-D-17-01092R2.

Is refeeding syndrome relevant for critically ill patients?

PURPOSE OF REVIEW

To summarize recent relevant studies regarding refeeding syndrome (RFS) in critically ill patients and provide recommendations for clinical practice.

RECENT FINDINGS

Recent knowledge regarding epidemiology of refeeding syndrome among critically ill patients, how to identify ICU patients at risk, and strategies to reduce the potential negative impact on outcome are discussed.

SUMMARY

RFS is a potentially fatal acute metabolic derangement that ultimately can result in marked morbidity and even mortality. These metabolic derangements in ICU patients differ from otherwise healthy patients with RFS, as there is lack of anabolism. This is because of external stressors inducing a hypercatabolic response among other reasons also reflected by persistent high glucagon despite initiation of feeding. Lack of a proper uniform definition complicates diagnosis and research of RFS. However, refeeding hypophosphatemia is commonly encountered during critical illness. The correlations between risk factors proposed by international guidelines and the occurrence of RFS in ICU patients remains unclear. Therefore, regular phosphate monitoring is recommended. Based on recent trials among critically ill patients, only treatment with supplementation of electrolytes and vitamins seems not sufficient. In addition, caloric restriction for several days and gradual increase of caloric intake over days is recommendable.

[The acutely ill oncological patient: admit to ICU or not?]

- 5-10% of all oncological patients will be admitted to ICU at some point.- Medical oncological patients are usually admitted due to respiratory insufficiency or sepsis.- Mortality among medical-oncological ICU patients has decreased to an average of 40%, with a wide spread per tumour type.- The main prognostic factors for ICU survival are: clinical condition, severity of the acute condition, tumour type, and some specific oncological conditions.- This article describes directive ICU admission criteria, subdivided into three categories of medical oncological patients. Although not validated, these criteria give guidance to clinicians in deciding whether ICU admission is a responsible course of action.- In patients with an uncertain prognosis an ICU trial can be useful.- ICU admission criteria are largely based on expert opinion, as sufficient scientific evidence is lacking. A multidisciplinary decision process is therefore important.- Ideally, decision-making about ICU treatment should take place at an early stage in primary health care or outpatient clinic; this is called Advance Care Planning.

[Shock-induced ischemic optic neuropathy]

BACKGROUND

Shock can lead to ischemic injury of organs. Ischemic injury of the optic nerve may even cause blindness.

CASE DESCRIPTION

A 61-year-old female patient was admitted to ICU with septic shock. When recovering, she was only able to determine the difference between light and dark; before admission her vision was good. Ophthalmologic examination revealed slow pupillary reflexes and pale, atrophic optic discs. The diagnosis of bilateral shock-induced ischemic optic neuropathy was made. The patient was permanently blind and traumatised by her experiences during her hospital stay when her blindness was not yet recognised.

CONCLUSION

Blindness caused by ischemic optic neuropathy is a rare and severe complication of shock that is usually irreversible. Early recognition is important in order to allow appropriate communication with, and approach of the patient to prevent traumatic experiences and promote rehabilitation.

[Extracorporeal life support for Legionella pneumonia]

BACKGROUND

Legionella species cause 5% of all community acquired pneumonias. However, Legionella pneumonia results relatively often in admission to the intensive care unit (ICU). A significant complication is the development of acute respiratory distress syndrome (ARDS). The ICU mortality rate for Legionella pneumonia is > 30% with conventional treatments.

CASE DESCRIPTION

A 64-year-old male was admitted to the ICU with respiratory failure due to Legionella pneumonia complicated by ARDS. Despite maximum conventional therapy being given, including lung-protective invasive mechanical ventilation and prone positioning, progressive hypoxaemia persisted. In collaboration with an extracorporeal life support (ECLS) centre, venovenous ECLS was initiated. Pulmonary function recovered and the patient was successfully weaned from VV-ECLS after 17 days. After three months of hospitalisation and rehabilitation, the patient was discharged home and able to perform his activities of daily living without assistance.

CONCLUSION

Legionella pneumonia relatively frequently results in ICU admission, and carries a high mortality with conventional treatments. ECLS may offer a solution if conventional therapies are not sufficiently effective.