Contribution of red blood cells to the compensation for hypocapnic alkalosis through plasmatic strong ion difference variations

Introduction Chloride shift is the movement of chloride between red blood cells (RBC) and plasma (and vice versa) caused by variations in pCO2. The aim of our study was to investigate changes in plasmatic strong ion diff erence (SID) during acute variations in pCO2 and their possible role in the compensation for hypocapnic alkalosis.Methods Patients admitted in this year to our ICU requiring extracorporeal CO2 removal were enrolled. Couples of measurements of gases and electrolytes on blood entering (v) and leaving (a) the respiratory membrane were analyzed. SID was calculated as [Na+] + [K+] + 2[Ca2+] \u2013 [Cl\u2013] \u2013 [Lac\u2013]. Percentage variations in SID (SID%) were calculated as (SIDv \u2013 SIDa) x 100 / SIDv. The same calculation was performed for pCO2 (pCO2%). Comparison between v and a values was performed by paired t test or the signed-rank test, as appropriate. Results Analysis was conducted on 205 sample-couples of six enrolled patients. A signifi cant diff erence (P <0.001) between mean values of v\u2013a samples was observed for pH (7.41 \ub1 0.05 vs. 7.51 \ub1 0.06), pCO2 (48 \ub1 6 vs. 35 \ub1 7 mmHg), [Na+] (136.3 \ub1 4.0 vs. 135.2 \ub1 4.0 mEq/l), [Cl\u2013] (101.5 \ub1 5.3 vs. 102.8 \ub1 5.2 mEq/l) and therefore SID (39.5 \ub1 4.0 vs. 36.9 \ub1 4.1 mEq/l). pCO2% and SID% signifi cantly correlated (r2 = 0.28, P <0.001). Graphical representation by quartiles of pCO2% is shown in Figure 1. Conclusions As a reduction in SID decreases pH, the observed movement of anions and cations probably limited the alkalinization caused by hypocapnia. In this model, the only source of electrolytes are blood cells (that is, no interstitium and no infl uence of the kidney is present); it is therefore conceivable to consider the observed phenomenon as the contribution of RBC for the compensation of acute hypocapnic alkalosi

Prolongation of antibiotic prophylaxis after clean and clean-contaminated surgery and surgical site infection.

AIM: Several guidelines have recommended that antibiotic prophylaxis (AMP) should be given only at premedication, except in selected cases. Conversely, in clinical practice, AMP is often unnecessarily prolonged after the surgical procedure. In this observational study, we evaluated the risk of surgical site infection (SSI) associated with the prolongation of AMP after clean and clean-contaminated surgery. METHODS: All consecutive patients who underwent a surgical procedure were eligible. AMP was always administered before the surgical incision. Prolongation of AMP for the first 24 hours was allowed only in presence of at least one risk factor for SSI: an ASA score >2 or surgical procedure longer than the specific cutoff (as indicated by the NNIS--the National Nosocomial Infections Surveillance System). SSIs were evaluated during the hospital stay and after hospital discharge. RESULTS: Three hundred fifty-eight patients were enrolled; 19 (5.3%) and 17 (6.5%) patients developed respectively intra-hospital and post hospital discharge SSIs. AMP prolongation for 24 hours in patients with at least one risk factor did not reduce the risk for intra-hospital SSI (OR 1.102; 95% CI: 0.336-3.612; P=0.873), while it increased the risk in patients without risk factors (OR: 8.99; 95% CI: 1.46-55.4; P=0.018). AMP longer than 24 hours raised the risk for intra-hospital and post hospital discharge SSI, regardless of the presence of risk factors (OR: 3.39; 95% CI 1.11-10.35; P=0.032 and OR: 5.39; 95% CI: 1.64-17.75; P=0.006, respectively.) CONCLUSION: Postoperative AMP prolongation should be avoided

Giant broadband refraction in the visible in a ferroelectric perovskite

In principle, materials with a broadband giant index of refraction (n&gt; 10) overcome chromatic aberration and shrink the diffraction limit down to the nanoscale, allowing new opportunities for nanoscopic imaging. They also open alternative avenues for the management of light to improve the performance of photovoltaic cells. Recent advances have demonstrated the feasibility of a giant refractive index in metamaterials at microwave and terahertz frequencies, but the highest reported broadband index of refraction in the visible is n&lt; 5. Here, we report a ferroelectric perovskite with an index of refraction of n&gt; 26 across the entire visible spectrum and demonstrate its behaviour using white-light and laser refraction and diffraction experiments. The sample, a solid-solution (KTN:Li) perovskite, has a naturally occurring room-temperature phase that propagates visible light along its normal axis without significant diffraction or chromatic dispersion, irrespective of beam size, intensity and angle of incidence