Effect of simulated body fluid formulation on orthopedic device apatite-forming ability assessment.

Integration of native bone into orthopedic devices is a key factor in long-term implant success. The material-tissue interface is generally accepted to consist of a hydroxyapatite layer so bioactive materials that can spontaneously generate this hydroxyapatite layer after implantation may improve patient outcomes. Per the ISO 22317:2014 standard, "Implants for surgery - In vitro evaluation for apatite-forming ability of implant materials," bioactivity performance statements can be assessed by soaking the material in simulated body fluid (SBF) and evaluating the surface for the formation of a hydroxyapatite layer; however, variations in test methods may alter hydroxyapatite formation and result in false-positive assessments. The goal of this study was to identify the effect of SBF formulation on bioactivity assessment. Bioglass® (45S5 and S53P4) and non-bioactive Ti-6Al-4V were exposed to SBF formulations varying in calcium ion and phosphate concentrations as well as supporting ion concentrations. Scanning electron microscopy and X-ray powder diffraction evaluation of the resulting hydroxyapatite layers revealed that SBF enriched with double or quadruple the calcium and phosphate ion concentrations increased hydroxyapatite crystal size and quantity compared to the standard formulation and can induce hydroxyapatite crystallization on surfaces traditionally considered non-bioactive. Altering concentrations of other ions, for example, bicarbonate, changed hydroxyapatite induction time, quantity, and morphology. For studies evaluating the apatite-forming ability of a material to support bioactivity performance statements, test method parameters must be adequately described and controlled. It is unclear if apatite formation after exposure to any of the SBF formulations is representative of an in vivo biological response. The ISO 23317 standard test method should be further developed to provide additional guidance on apatite characterization and interpretation of the results.

Pharmacologic Treatment of Intensive Care Unit Delirium and the Impact on Duration of Delirium, Length of Intensive Care Unit Stay, Length of Hospitalization, and 28-Day Mortality.

OBJECTIVE: To determine whether treatment of delirium affects outcomes. PATIENTS AND METHODS: A retrospective cohort study of patients admitted to the medical intensive care unit (ICU) from July 1, 2015, through June 30, 2016, was conducted. Patients with ICU delirium, defined by a positive Confusion Assessment Method for the ICU score, were included. Patients were stratified into 4 treatment groups based on exposure to melatonin and antipsychotic agents during ICU stay: no pharmacologic treatment, melatonin only, antipsychotics only, and both melatonin and antipsychotics. A time-dependent cause-specific hazards model with death as a competing risk was used to evaluate the effect of melatonin or antipsychotic drug use for delirium on duration of ICU delirium, length of ICU stay, and length of hospitalization. A logistic regression was used to evaluate 28-day mortality. Covariates significantly associated with exposure to melatonin and antipsychotics were included in the minimally adjusted model. Covariates significantly associated in the minimally adjusted model were included in a final adjusted model. RESULTS: A total of 449 admissions to the medical ICU were included in the analysis. Exposure to melatonin or antipsychotic agents did not reduce the duration of ICU delirium, ICU/hospital length of stay, or 28-day mortality. However, antipsychotic use only was associated with longer hospitalization. CONCLUSION: Antipsychotic drugs for the treatment ICU delirium may not provide the benefit documented in earlier literature. Further investigation on patient selection, type of antipsychotic, and dosing is needed.

Preliminary noise reduction efforts in a medical intensive care unit.

Noise is a significant contributor to sleep disruption in the intensive care unit (ICU) that may result in increased patient morbidity such as delirium and prolonged length of stay in ICU. We conducted a pre-post intervention study in a 24-bed tertiary care academic medical ICU to reduce the mean noise levels. Baseline dosimeter recordings of ICU noise levels demonstrated a mean noise level of 54.2 A-weighted decibels (dBA) and peak noise levels of 109.9 dBA, well above the Environmental Protection Agency's recommended levels. There were 1735 episodes of "defects" (maximum noise levels > 60 dBA). Following implementation of multipronged interventions, although the mean noise levels did not change significantly between pre- and post-intervention (54.2 vs 53.8 dBA; p = 0.96), there was a significant reduction in the number of "defects" post-intervention (1735 vs 1289, p ≤ 0.000), and the providers felt that the patients were sleeping longer in the ICU post-intervention.