Prevalence of Vitamin D Deficiency and Associated Factors in Critically Ill Patients: A Multicenter Observational Study

Background: Vitamin D deficiency is common in the general population worldwide, and the prevalence and severity of vitamin D deficiency increase in critically ill patients. The prevalence of vitamin D deficiency in a community-based cohort in Northern Taiwan was 22.4%. This multicenter cohort study investigated the prevalence of vitamin D deficiency and associated factors in critically ill patients in Northern Taiwan. Methods: Critically ill patients were enrolled and divided into five groups according to their length of stay at intensive care units (ICUs) during enrolment as follows: group 1, <2 days with expected short ICU stay; group 2, <2 days with expected long ICU stay; group 3, 3-7 days; group 4, 8-14 days; and group 5, 15-28 days. Vitamin D deficiency was defined as a serum 25-hydroxyvitamin D (25(OH)D) level < 20 ng/ml, and severe vitamin D deficiency was defined as a 25(OH)D level < 12 ng/ml. The primary analysis was the prevalence of vitamin D deficiency. The exploratory analyses were serial follow-up vitamin D levels in group 2, associated factors for vitamin D deficiency, and the effect of vitamin D deficiency on clinical outcomes in critically ill patients. Results: The prevalence of vitamin D deficiency was 59% [95% confidence interval (CI) 55-62%], and the prevalence of severe vitamin D deficiency was 18% (95% CI 15-21%). The median vitamin D level for all enrolled critically ill patients was 18.3 (13.7-23.9) ng/ml. In group 2, the median vitamin D levels were <20 ng/ml during the serial follow-up. According to the multivariable analysis, young age, female gender, low albumin level, high parathyroid hormone (PTH) level, and high sequential organ failure assessment (SOFA) score were significantly associated risk factors for vitamin D deficiency. Patients with vitamin D deficiency had longer ventilator use duration and length of ICU stay. However, the 28- and 90-day mortality rate were not associated with vitamin D deficiency. Conclusions: This study demonstrated that the prevalence of vitamin D deficiency is high in critically ill patients. Age, gender, albumin level, PTH level, and SOFA score were significantly associated with vitamin D deficiency in these patients.

Determination of the energy requirements in mechanically ventilated critically ill elderly patients in different BMI groups using the Harris-Benedict equation

BACKGROUND

Due to studies on calorie requirement in mechanically ventilated critically ill elderly patients are few, and indirect calorimetry (IC) is not available in every intensive care unit (ICU). The aim of this study was to compare IC and Harris-Benedict (HB) predictive equation in different BMI groups.

METHODS

A total of 177 mechanically ventilated critically ill elderly patients (≧65 years old) underwent IC for measured resting energy expenditure (MREE). Estimated calorie requirement was calculated by the HB equation, using actual body weight (ABW) and ideal body weight (IBW) separately. Patients were divided into four BMI groups. One-way ANOVA and Pearson's correlation coefficient were used for statistical analyses.

RESULTS

The mean MREE was 1443.6 ± 318.2 kcal/day, HB(ABW) was 1110.9 ± 177.0 kcal/day and HB(IBW) was 1101.5 ± 113.1 kcal/day. The stress factor (SFA = MREE ÷ HB(ABW)) was 1.43 ± 0.26 for the underweight, 1.30 ± 0.27 for the normal weight, 1.20 ± 0.19 for the overweight, and 1.20 ± 0.31 for the obese. The SFI (SFI = MREE ÷ HB(IBW)) was 1.24 ± 0.24 for the underweight, 1.31 ± 0.26 for the normal weight, 1.36 ± 0.21 for the overweight, and 1.52 ± 0.39 for the obese. MREE had significant correlation both with REE(ABW) = HB(ABW) × SFA (r = 0.46; P < 0.0001) and REE(IBW) = HB(IBW) × SFI (r = 0.43; P < 0.0001).

CONCLUSION

IC is the best accurate method for assessing calorie requirement of mechanically ventilated critically ill elderly patients. When IC is not available, using the predictive HB equation is an alternative choice. Calorie requirement can be predicted by HB(ABW) × 1.20-1.43 for critically ill elderly patients according to different BMI groups, or using HB(IBW) × 1.24-1.52 for patients with edema, ascites or no available body weight data.

Probing the Interlayer Exciton Physics in a MoS2/MoSe2/MoS2 van der Waals Heterostructure

Stacking atomic monolayers of semiconducting transition metal dichalcogenides (TMDs) has emerged as an effective way to engineer their properties. In principle, the staggered band alignment of TMD heterostructures should result in the formation of interlayer excitons with long lifetimes and robust valley polarization. However, these features have been observed simultaneously only in MoSe₂/WSe₂ heterostructures. Here we report on the observation of long-lived interlayer exciton emission in a MoS₂/MoSe₂/MoS₂ trilayer van der Waals heterostructure. The interlayer nature of the observed transition is confirmed by photoluminescence spectroscopy, as well as by analyzing the temporal, excitation power, and temperature dependence of the interlayer emission peak. The observed complex photoluminescence dynamics suggests the presence of quasi-degenerate momentum-direct and momentum-indirect bandgaps. We show that circularly polarized optical pumping results in long-lived valley polarization of interlayer exciton. Intriguingly, the interlayer exciton photoluminescence has helicity opposite to the excitation. Our results show that through a careful choice of the TMDs forming the van der Waals heterostructure it is possible to control the circular polarization of the interlayer exciton emission.

Three dimensional microfluidics with embedded microball lenses for parallel and high throughput multicolor fluorescence detection

We report a 3D microfluidic device with 32 detection channels and 64 sheath flow channels and embedded microball lens array for high throughput multicolor fluorescence detection. A throughput of 358 400 cells/s has been accomplished. This device is realized by utilizing solid immersion micro ball lens arrays for high sensitivity and parallel fluorescence detection. High refractive index micro ball lenses (n = 2.1) are embedded underneath PDMS channels close to cell detection zones in channels. This design permits patterning high N.A. micro ball lenses in a compact fashion for parallel fluorescence detection on a small footprint device. This device also utilizes 3D microfluidic fabrication to address fluid routing issues in two-dimensional parallel sheath focusing and allows simultaneous pumping of 32 sample channels and 64 sheath flow channels with only two inlets.

Prognostic value of dynamic soluble triggering receptor expressed on myeloid cells in bronchoalveolar lavage fluid of patients with ventilator-associated pneumonia

BACKGROUND AND OBJECTIVE

The aim of this study was to investigate the time course, and correlation with prognosis, of BAL fluid concentrations of soluble triggering receptor expressed on myeloid cells (sTREM-1) in patients with ventilator-associated pneumonia (VAP).

METHODS

The study included 35 patients with clinically diagnosed VAP, eight of whom were BAL fluid culture-negative and 27 BAL fluid culture-positive (16 survivors, 11 non-survivors). sTREM-1 levels were measured in BAL fluid of these mechanically ventilated patients, at the time of diagnosis, on days 4-5 and on days 7-9. The time course of this biomarker and its prognostic value for outcome in patients with culture-positive VAP were assessed.

RESULTS

sTREM-1 concentrations were significantly greater in culture-positive VAP patients than in culture-negative VAP patients. sTREM-1 levels decreased significantly with time in surviving patients with culture-positive VAP, but increased significantly with time in non-survivors. In contrast, PaO(2)/fraction of inspired oxygen (FiO(2)) increased significantly with time in survivors and decreased significantly with time in non-survivors. At a cut-off value of -10 pg/mL 7-9 days after initial diagnosis, sTREM levels had a sensitivity of 90% and a specificity of 87.5% for predicting mortality.

CONCLUSIONS

sTREM-1 concentrations in BAL fluid are of potential prognostic value in patients with VAP.

Effects of erlotinib on pulmonary function and airway remodeling after sensitization and repeated allergen challenge in Brown-Norway rats

Erlotinib, an EGFR tyrosine kinase inhibitor, can inhibit the proliferation and survival of cancer cells. It has been widely used to treat non-small cell lung cancer. This study aimed to evaluate the effects of erlotinib on bronchial hyperresponsiveness, airway inflammation, and airway remodeling in sensitized, ovalbumin-challenged rats. Two experimental groups of Brown-Norway rats were sensitized and repeatedly challenged by breathing aerosolized ovalbumin. Since Day 1, one group was given oral erlotinib (OA-erlotinib group) while the other group was given only oral saline (OA-saline group). The control group was sensitized and challenged using saline. All were anesthetized and paralyzed, and pulmonary function tests conducted at baseline and after provocation with varying doses of acetylcholine. Lung tissues were examined for airway inflammation, airway remodeling, and Th2-related cytokine mRNA expression. Results showed that the OA-erlotinib group had better pulmonary function and less airway inflammation, Th2-related cytokines and their mRNA expression, and airway remodeling compared to the OA-saline group. In conclusion, erlotinib effectively prevents bronchial hyperreactivity, airway inflammation, Th2-related cytokine mRNA expression, and airway remodeling after sensitization and repeated allergen challenge in Brown-Norway rats.