Effetto della contaminazione ematica sul distacco di tre differenti tipi di brackets autoleganti: studio sperimentale in vitro

Objectives

To assess the effect of blood contamination on the bonding and bond-failure site of 3 different types of self-ligating bracket.

Materials and methods

Two hundred forty bovine permanent mandibular incisors were randomly divided into 12 groups, each containing 20 specimens. Three different self-ligating brackets (Smart Clip - 3 M Unitek, Monrovia, California, USA; Damon - Ormco, Glendora, California, USA; and Quick - Forestadent, Pforzheim, Germania) were bonded to the teeth with Orthosolo primer (Ormco, Glendora, California, USA) and Trasbond XT composite (3 M Unitek, Monrovia, California, USA). Bonding was tested under different surface enamel conditions: dry, contaminated with blood before priming, contaminated with blood after priming, and contaminated with blood before and after priming. After bonding, all samples were stored in distilled water at room temperature for 24 hours. Shear bond strength was then evaluated with a universal testing machine (Mod. 4301, Instron Corp., Canton, Massachussets, USA). After bond failure, the bracket bases and the enamel surfaces were examined under an optical microscope (Stereomicroscope SR, Zeiss, Oberkochen, Germany) at 10 x magnification, and the amount of adhesive left on the enamel surface was rated with the adhesive remnant index (ARI). All the data were statistically analyzed (Chi-square test; level of significance p < 0.05).

Results and conclusions

ARIs of 2 were more frequent among samples bonded to dry enamel, whereas samples bonded to blood-contaminated enamel (before, after, or before and after priming) exhibited a higher frequency of ARI 0. However, there were no significant differences between the ARI scores for the 3 conditions of contaminated enamel or for those related to the 3 types of self-ligating brackets tested.     

Contributions of vascular flow and pulmonary capillary pressure to ventilator-induced lung injury

OBJECTIVE: To evaluate the influence of vascular flow on ventilator-induced lung injury independent of vascular pressures. DESIGN: Laboratory study. SETTING: Hospital laboratory. SUBJECTS: Thirty-two New Zealand White rabbits. INTERVENTIONS: Thirty-two isolated perfused rabbit lungs were allocated into four groups: low flow/low pulmonary capillary pressure; high flow/high pulmonary capillary pressure; low flow/high pulmonary capillary pressure, and high flow/low pulmonary capillary pressure. All lungs were ventilated with peak airway pressure 30 cm H2O and positive end-expiratory pressure 5 cm H2O for 30 mins. MEASUREMENTS AND MAIN RESULTS: Outcome measures included frequency of gross structural failure (pulmonary rupture), pulmonary hemorrhage, edema formation, changes in lung compliance, pulmonary vascular resistance, and pulmonary ultrafiltration coefficient. Lungs exposed to high pulmonary vascular flow ruptured more frequently, displayed more hemorrhage, developed more edema, suffered larger decreases in compliance, and had larger increases in vascular resistance than lungs exposed to low vascular flows (p < .05 for each pairwise comparison between groups). CONCLUSIONS: These findings suggest that high pulmonary vascular flows might exacerbate ventilator-induced lung injury independent of their effects on pulmonary vascular pressures.     

Peripheral arterial blood pressure monitoring adequately tracks central arterial blood pressure in critically ill patients: an observational study

Introduction  

Invasive arterial blood pressure monitoring is a common practice in intensive care units (ICUs). Accuracy of invasive blood pressure monitoring is crucial in evaluating the cardiocirculatory system and adjusting drug therapy for hemodynamic support. However, the best site for catheter insertion is controversial. Lack of definitive information in critically ill patients makes it difficult to establish guidelines for daily practice in intensive care. We hypothesize that peripheral and central mean arterial blood pressures are interchangeable in critically ill patients.     

No changes in time trial performance of master endurance athletes after 4 weeks on a low carbohydrate diet

The purpose of the present study was to evaluate the effects of a 4-week low-carbohydrate (CHO) diet regimen on body weight, exercise performance and hormonal response to running in master athletes. Six endurance master athletes performed three 30-min time trials, before (TT1), after 15 days (TT2) and after 30 days (TT3) on a low CHO diet. Blood samples were collected for hormonal and lactate measurements. After 15 days body weight had decreased (TT1 72.3 ± 2.4 kg, TT2 70.0 ± 2.7 kg; P = 0.006) and then remained stable. No differences were observed in performance (TT1 7,015 ± 273 m, TT2 6,920 ± 286 m, TT3 7,202 ± 315 m) and in the insulin/glucagon ratio. After 2 and 4 weeks, adrenocorticotropic hormone decreased significantly both at rest (baseline: TT1 42.5 ± 7.8 pg·ml^?1, TT3 21.6 ± 3.2 pg·ml^?1) and during exercise (end of exercise: TT1 120 ± 20 pg·ml^?1, TT2 80 ± 16 pg·ml^?1, TT3 31 ± 2 pg·ml^?1). Baseline cortisol concentrations had increased significantly after as little as 15 days on the low CHO diet. The results of the present study demonstrate no changes in time trial performance in master endurance athletes after 4 weeks on a low CHO diet. However, an effect on the hypothalamic pituitary adrenal axis emerged.     

A new automated method versus continuous positive airway pressure method for measuring pressure-volume curves in patients with acute lung injury

Objective  To compare pressure–volume (P–V) curves obtained with the Galileo ventilator with those obtained with the CPAP method in patients with acute lung injury (ALI) or acute respiratory distress syndrome (ARDS). Design  Prospective, observational study. Setting  General critical care center. Patients and participants  Patients with ALI/ARDS and receiving mechanical ventilation. Interventions  Pressure–volume curves were obtained in random order with the CPAP technique and with the software PV Tool-2 (Galileo ventilator). Measurements and results  In ten consecutive patients, airway pressure was measured by a pressure transducer and changes in lung volume were measured by respiratory inductive plethysmography. P–V curves were fitted to a sigmoidal equation with a mean R ² of 0.994 ± 0.003. Intraclass correlation coefficients were all >0.75 (P < 0.001 at all pressure levels). Lower (LIP) and upper inflection (UIP), and deflation maximum curvature (PMC) points calculated from the fitted variables showed a good correlation between methods with intraclass correlation coefficients of 0.98 (0.92, 0.99), 0.92 (0.69, 0.98), and 0.97 (0.86, 0.98), respectively (P < 0.001 in all cases). Bias and limits of agreement for LIP (0.51 ± 0.95 cmH₂O; −1.36 to 2.38 cmH₂O), UIP (0.53 ± 1.52 cmH₂O; −2.44 to 3.50 cmH₂O), and PMC (−0.62 ± 0.89 cmH₂O; −2.35 to 1.12 cmH₂O) obtained with the two methods in the same patient were clinically acceptable. No adverse effects were observed. Conclusion  The PV Tool-2 built into the Galileo ventilator is equivalent to the CPAP method for tracing static P–V curves of the respiratory system in critically ill patients receiving mechanical ventilation. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.