Effect of Intravenous 25OHD Supplementation on Bone Turnover and Inflammation in Prolonged Critically Ill Patients

Critically ill patients have low circulating 25-hydroxyvitamin D (25OHD), vitamin D binding protein (DBP), and 1,25-dihydroxyvitamin D [1,25(OH)₂D]. Low 25OHD is associated with poor outcomes, possibly explained by its effect on bone and immunity. In this prospective, randomized double-blind, placebo-controlled study, we investigated the feasibility of normalizing 25OHD in prolonged (>10 days) critically ill patients and the effects thereof on 1,25(OH)₂D, bone metabolism, and innate immunity. Twenty-four patients were included and compared with 24 matched healthy subjects. Patients were randomized to either intravenous bolus of 200 μg 25OHD followed by daily infusion of 15 μg 25OHD for 10 days, or to placebo. Parameters of vitamin D, bone and mineral metabolism, and innate immune function were measured. As safety endpoints, ICU length of stay and mortality were registered. Infusion of 25OHD resulted in a sustained increase of serum 25OHD (from median baseline 9.2 -16.1 ng/ml at day 10), which, however, remained below normal levels. There was no increase in serum 1,25(OH)₂D but a slight increase in serum 24,25(OH)₂D. Mineral homeostasis, innate immunity and clinical safety endpoints were unaffected. Thus, intravenous 25OHD administration during critical illness increased serum 25OHD concentrations, though less than expected from data in healthy subjects, which suggests illness-induced alterations in 25OHD metabolism and/or increased 25OHD distribution volume. The increased serum 25OHD concentrations were not followed by a rise in 1,25(OH)₂D nor were bone metabolism or innate immunity affected, which suggests that low 25OHD and 1,25OHD levels are part of the adaptive response to critical illness.

Impact of a VAP bundle in Belgian intensive care units

Background

In order to decrease the incidence of ventilator-associated pneumonia (VAP) in Belgium, a national campaign for implementing a VAP bundle involving assessment of sedation, cuff pressure control, oral care with chlorhexidine and semirecumbent position, was launched in 2011–2012. This report will document the impact of this campaign.

Methods

On 1 day, once a year from 2010 till 2016, except in 2012, Belgian ICUs were questioned about their ventilated patients. For each of these, data about the application of the bundle and the possible treatment for VAP were recorded.

Results

Between 36.6 and 54.8% of the 120 Belgian ICUs participated in the successive surveys. While the characteristics of ventilated patients remained similar throughout the years, the percentage of ventilated patients and especially the duration of ventilation significantly decreased before and after the national VAP bundle campaign. Ventilator care also profoundly changed: Controlling cuff pressure, head positioning above 30° were obtained in more than 90% of cases. Oral care was more frequently performed within a day, using more concentrated solutions of chlorhexidine. Subglottic suctioning also was used but in only 24.7% of the cases in the last years. Regarding the prevalence of VAP, it significantly decreased from 28% of ventilated patients in 2010 to 10.1% in 2016 (p ≤ 0.0001).

Conclusion

Although a causal relationship cannot be inferred from these data, the successive surveys revealed a potential impact of the VAP bundle campaign on both the respiratory care of ventilated patients and the prevalence of VAP in Belgian ICUs encouraging them to follow the guidelines.

Introducing TOPMAST, the first double-blind randomized clinical trial specifically dedicated to perioperative maintenance fluid therapy in adults

BACKGROUND

Although prescribed to every patient undergoing surgery, maintenance fluid therapy is a poorly researched part of perioperative fluid therapy. The tonicity of the chosen solutions, could be an important cause of morbidity, with hyponatremia being a potential side effect of hypotonic solutions, where isotonic solution could lead to fluid overload.

METHODS

The TOPMAST-trial is an ongoing prospective single-center double-blind randomized trial comparing an isotonic and a hypotonic maintenance fluid strategy during and after surgery in patients undergoing different types of major thoracic surgery. Patients receive NaCl 0.9% in glucose 5% with an added 40 mmol L-1 of potassium chloride or a premixed solution containing 54 mmol L-1 sodium, 55 mmol L-1 chloride and 26 mmol of potassium at a rate of 27 mL per kg of body weight per day. The primary hypothesis is that isotonic maintenance solutions cause a more positive perioperative fluid balance than hypotonic fluids. Different secondary safety endpoints will be explored, especially the effect of the study treatments on the occurrence electrolyte disturbances (e.g. hyponatremia, hyperchloremia) and a set of clinical endpoints. Efficacy endpoints include the need for resuscitation fluids and assessment of renal and hormonal adaptive mechanisms. An anticipated 68 patients will be included between March 2017 and January 2018.

DISCUSSION

The study will provide the most comprehensive evaluation of clinically important outcomes associated with the choice of perioperative maintenance fluid therapy.

Critical illness-induced bone loss is related to deficient autophagy and histone hypomethylation

BACKGROUND

Survivors of critical illness are at increased risk of fractures. This may be due to increased osteoclast formation during critical illness, leading to trabecular bone loss. Such bone loss has also been observed in Paget's disease, and has been related to deficient autophagy. Deficient autophagy has also been documented in vital organs and skeletal muscle of critically ill patients. The objective of this study was to investigate whether deficient autophagy can be linked to critical illness-induced bone loss.

METHODS

Osteoclasts grown in vitro and their precursor cells isolated from peripheral blood of critically ill patients and from matched healthy volunteers were analysed for the expression of autophagy genes (SQSTM1, Atg3 and Atg7), and proteins (p62, Atg-5, and microtubule-associated protein light chain 3-II (LC3-II)) and for autophagy and epigenetic signalling factors via PCR arrays and were treated with the autophagy inducer rapamycin. The effect of rapamycin was also investigated at the tissue level in an in vivo rabbit model of critical illness.

RESULTS

Many more osteoclasts formed in vitro from the blood precursor cells isolated from critically ill patients, which accumulated p62, and displayed reduced expression of Atg5, Atg7, and LC3-II compared to healthy controls, suggesting deficient autophagy, whilst addition of rapamycin reduced osteoclast formation. PCR arrays revealed a down-regulation of histone methyltransferases coupled with an up-regulation of negative regulators of autophagy. Critically ill rabbits displayed a reduction in trabecular and cortical bone, which was rescued with rapamycin.

CONCLUSIONS

Deficient autophagy in osteoclasts and their blood precursor cells at least partially explained aberrant osteoclast formation during critical illness and was linked to global histone hypomethylation. Treatment with the autophagy activator Rapamycin reduced patient osteoclast formation in vitro and reduced the amount of bone loss in critically ill rabbits in vivo. These findings may help to develop novel therapeutic targets to prevent critical illness-induced bone loss.

Does the surface-treated AN69 membrane prolong filter survival in CRRT without anticoagulation?

PURPOSE

The need for continuous anticoagulation remains a significant drawback in continuous renal replacement therapy (CRRT), especially in patients with increased bleeding risk. Polyethyleneimine treatment of the AN69 membrane (AN69ST) reduces thrombogenicity through decreased contact activation and promotion of heparin binding. The aim of this study is to evaluate whether this membrane prolongs filter survival in CRRT without anticoagulation.

METHODS

A single-center, prospective, randomized, double-blind controlled trial with cross-over design comparing filter survival with the AN69ST membrane and the original AN69 membrane in 39 patients treated with continuous venovenous hemofiltraton (CVVH) without additional heparin.

RESULTS

Filter survival with the AN69ST membrane (n = 75) was 14.2 ± 8.2 h, which is not significantly different from the 13.3 ± 10.3 h for the original AN69 membrane (n = 76; p = 0.59). Limiting the analysis to those treatments that were interrupted for filter clotting yielded similar results: 14.4 ± 8.2 h for the AN69 ST membrane (n = 62) versus 14.1 ± 7.5 h for the original AN69 membrane (n = 56) (p = 0.93).

CONCLUSIONS

Compared with the original AN69 membrane, the surface-treated AN69ST membrane does not prolong filter survival during CVVH without systemic anticoagulation and with the CRRT settings used in this study.

Critical illness-related bone loss is associated with osteoclastic and angiogenic abnormalities

Critically ill patients are at increased risk of fractures during rehabilitation, and can experience impaired healing of traumatic and surgical bone fractures. In addition, markers of bone resorption are markedly increased in critically ill patients, while markers of bone formation are decreased. In the current study, we have directly investigated the effect of critical illness on bone metabolism and repair. In a human in vitro model of critical illness, Fluorescence-activated cell sorting (FACS) analysis revealed an increase in circulating CD14+/CD11b+ osteoclast precursors in critically ill patient peripheral blood compared to healthy controls. In addition, the formation of osteoclasts was increased in patient peripheral blood mononuclear cell (PBMC) cultures compared to healthy controls, both in the presence and absence of osteoclastogenic factors receptor activator of NF-κB ligand (RANKL) and macrophage colony-stimulating factor (M-CSF). Culturing PBMCs with 10% critically ill patient serum further increased osteoclast formation and activity in patient PBMCs only, and neutralization studies revealed that immunoglobulin G (IgG) antibody signaling through the immunoreceptor Fc receptor common γ chain III (FcRγIII) played an important role. When analyzing bone formation, no differences in osteogenic differentiation were observed using human periosteal-derived cells (hPDCs) treated with patient serum in vitro, but a decrease in the expression of vascular endothelial growth factor receptor 1 (VEGF-R1) suggested impaired vascularization. This was confirmed using serum-treated hPDCs implanted onto calcium phosphate scaffolds in a murine in vivo model of bone formation, where decreased vascularization and increased osteoclast activity led to a decrease in bone formation in scaffolds with patient serum-treated hPDCs. Together, these findings may help to define novel therapeutic targets to prevent bone loss and optimize fracture healing in critically ill patients.

Early versus late parenteral nutrition in critically ill adults

BACKGROUND

Controversy exists about the timing of the initiation of parenteral nutrition in critically ill adults in whom caloric targets cannot be met by enteral nutrition alone.

METHODS

In this randomized, multicenter trial, we compared early initiation of parenteral nutrition (European guidelines) with late initiation (American and Canadian guidelines) in adults in the intensive care unit (ICU) to supplement insufficient enteral nutrition. In 2312 patients, parenteral nutrition was initiated within 48 hours after ICU admission (early-initiation group), whereas in 2328 patients, parenteral nutrition was not initiated before day 8 (late-initiation group). A protocol for the early initiation of enteral nutrition was applied to both groups, and insulin was infused to achieve normoglycemia.

RESULTS

Patients in the late-initiation group had a relative increase of 6.3% in the likelihood of being discharged alive earlier from the ICU (hazard ratio, 1.06; 95% confidence interval [CI], 1.00 to 1.13; P=0.04) and from the hospital (hazard ratio, 1.06; 95% CI, 1.00 to 1.13; P=0.04), without evidence of decreased functional status at hospital discharge. Rates of death in the ICU and in the hospital and rates of survival at 90 days were similar in the two groups. Patients in the late-initiation group, as compared with the early-initiation group, had fewer ICU infections (22.8% vs. 26.2%, P=0.008) and a lower incidence of cholestasis (P<0.001). The late-initiation group had a relative reduction of 9.7% in the proportion of patients requiring more than 2 days of mechanical ventilation (P=0.006), a median reduction of 3 days in the duration of renal-replacement therapy (P=0.008), and a mean reduction in health care costs of €1,110 (about $1,600) (P=0.04).

CONCLUSIONS

Late initiation of parenteral nutrition was associated with faster recovery and fewer complications, as compared with early initiation. (Funded by the Methusalem program of the Flemish government and others; EPaNIC ClinicalTrials.gov number, NCT00512122.).

Intensive insulin therapy for patients in paediatric intensive care: a prospective, randomised controlled study

BACKGROUND

Critically ill infants and children often develop hyperglycaemia, which is associated with adverse outcome; however, whether lowering blood glucose concentrations to age-adjusted normal fasting values improves outcome is unknown. We investigated the effect of targeting age-adjusted normoglycaemia with insulin infusion in critically ill infants and children on outcome.

METHODS

In a prospective, randomised controlled study, we enrolled 700 critically ill patients, 317 infants (aged <1 year) and 383 children (aged >or=1 year), who were admitted to the paediatric intensive care unit (PICU) of the University Hospital of Leuven, Belgium. Patients were randomly assigned by blinded envelopes to target blood glucose concentrations of 2.8-4.4 mmol/L in infants and 3.9-5.6 mmol/L in children with insulin infusion throughout PICU stay (intensive group [n=349]), or to insulin infusion only to prevent blood glucose from exceeding 11.9 mmol/L (conventional group [n=351]). Patients and laboratory staff were blinded to treatment allocation. Primary endpoints were duration of PICU stay and inflammation. Analysis was by intention to treat. This study is registered with ClinicalTrials.gov, number NCT00214916.

FINDINGS

Mean blood glucose concentrations were lower in the intensive group than in the conventional group (infants: 4.8 [SD 1.2] mmol/L vs 6.4 [1.2] mmol/L, p<0.0001; children: 5.3 [1.1] mmol/L vs 8.2 [3.3] mmol/L, p<0.0001). Hypoglycaemia (defined as blood glucose <or=2.2 mmol/L) occurred in 87 (25%) patients in the intensive group (p<0.0001) versus five (1%) patients in the conventional group; hypoglycaemia defined as blood glucose less than 1.7 mmol/L arose in 17 (5%) patients versus three (1%) (p=0.001). Duration of PICU stay was shortest in the intensively treated group (5.51 days [95% CI 4.65-6.37] vs 6.15 days [5.25-7.05], p=0.017). The inflammatory response was attenuated at day 5, as indicated by lower C-reactive protein in the intensive group compared with baseline (-9.75 mg/L [95% CI -19.93 to 0.43] vs 8.97 mg/L [-0.9 to 18.84], p=0.007). The number of patients with extended (>median) stay in PICU was 132 (38%) in the intensive group versus 165 (47%) in the conventional group (p=0.013). Nine (3%) patients died in the intensively treated group versus 20 (6%) in the conventional group (p=0.038).

INTERPRETATION

Targeting of blood glucose concentrations to age-adjusted normal fasting concentrations improved short-term outcome of patients in PICU. The effect on long-term survival, morbidity, and neurocognitive development needs to be investigated.

FUNDING

Research Foundation (Belgium); Research Fund of the University of Leuven (Belgium) and the EU Information Society Technologies Integrated project "CLINICIP"; and Institute for Science and Technology (Belgium).

Vitamin D resistance

Vitamin D is a secosteroid of nutritional origin but can also be generated in the skin by ultraviolet light. After two hydroxylations 1,25-(OH)2 vitamin D avidly binds and activates the vitamin D receptor (VDR), a nuclear transcription factor, hereby regulating a large number of genes. The generation of VDR deficient mice has expanded the knowledge on vitamin D from a calcium-regulating hormone to a humoral factor with extensive actions. The effects of the vitamin D system on calcium and bone homeostasis are largely mediated by promoting active intestinal calcium transport via the induction of the epithelial calcium channel TRPV6. Although VDR is redundant in bone, it may regulate the differentiation and function of several bone cells. In skin, VDR expression in keratinocytes is essential in a ligand-independent manner for the maintenance of the normal hair cycle. Therefore, VDR but not vitamin D deficiency results in alopecia. Moreover, 1,25-(OH)2 vitamin D impairs the proliferation not only of keratinocytes but also of many cell types by regulating the expression of cell cycle genes, leading to a G1 cell cycle arrest. In addition, VDR inactivation in mice results in high renin hypertension, cardiac hypertrophy and thrombogenesis. Finally, a dual effect of vitamin D was observed in the immune system where it stimulates the innate immune system while tapering down excessive activation of the acquired immune system. Taken together, the vitamin D endocrine system not only regulates calcium homeostasis but affects several systems mainly by altering gene expression but also by ligand-independent actions.

Disorders of calcium homeostasis

To ensure a multitude of essential cellular functions, the extracellular concentration of calcium is maintained within a narrow physiological range. This depends on integrated regulation of calcium fluxes with respect to the intestine, kidneys and bone. The precise regulation of serum calcium is controlled by calcium itself, through a calcium receptor and several hormones, the most important of which are parathyroid hormone and 1,25(OH)(2) vitamin D. This balance can be disturbed by mutations in the calcium-sensing receptor, inappropriately high or low levels of parathyroid hormone, resistance to parathyroid hormone effects, insufficient intake or production of 1,25(OH)(2) vitamin D and inactivation of the vitamin D receptor. Mineral homeostasis is moreover influenced by many other systemic factors (e.g. sex steroid, thyroid and glucocorticoid hormones) or humoral factors (e.g. cytokines and growth factors). A specific example is the major abnormalities of mineral homeostasis in case of malignancy by excessive production of parathyroid hormone-related peptide resulting in hypercalcaemia. Several new drugs have been developed based on factors in this axis, including calcimimetics, calcilytics, vitamin D analogues and parathyroid hormone-related peptide inhibitors.