A prospective randomized trial of the surgical blood order equation for ordering red cells for total hip arthroplasty patients

BACKGROUND: The majority of crossmatched blood is for surgical patients, and most of it is never transfused. An alternative system for ordering red cell (RBC) units, called the surgical blood order equation (SBOE), which incorporates specific patient variables for surgical patients, has been developed. STUDY DESIGN AND METHODS: A prospective double-blind randomized trial compared the SBOE with the maximal surgical blood order schedule (MSBOS) system for ordering allogeneic RBC units in 60 patients undergoing total hip arthroplasty. Autologous RBCs were available for none of the patients. RESULTS: There were no differences in patient demographic, surgical, or laboratory variables at any time. The median number (range) of allogeneic RBC units ordered was 2 (2-3) for the MSBOS and 0 (0-3) for the SBOE (p<0.0001). The SBOE ordered the correct number of RBC units for 58 percent of patients, while the MSBOS did so for 7 percent (p<0.0001). The SBOE had a lower crossmatch-to-transfusion ratio than the MSBOS (0.83 vs. 4.12). Costs were also lower with the SBOE. CONCLUSION: Incorporation of patient factors in the use of the SBOE system resulted in increased efficiency of blood-ordering practices for total hip arthroplasty.     

Effects of nimodipine,Bay K 8644 and pinacidil on α1- and α2-adrenoceptor-mediated vasoconstriction in human hand veins

The effects of nimodipine, Bay K 8644 and pinacidil, three drugs interfering with transmembrane Ca²⁺ fluxes in different ways, were investigated in isolated human hand veins. Their ability to influence the concentration-response relationship for noradrenaline (NA) was assessed in the absence and presence of prazosin or rauwolscine. The contractile response to NA was almost abolished in Ca²⁺-free medium. Nimodipine and pinacidil depressed the NA concentration-response curve both in the absence and presence of α-adrenoceptor blockers. The NA response was only partially inhibited by nimodipine, indicating that NA may activate nimodipine-insensitive influx pathways, presumably receptor-operated calcium channels. Pinacidil inhibited the contractile response to 124 mM K⁺ and reduced the NA-induced contraction in the presence of nimodipine, suggesting that pinacidil has actions other than the opening of potassium channels and subsequent membrane hyperpolarization. Bay K 8644 increased the NA potency fourfold in the presence of rauwolscine, whereas it had no effect on the NA response in the presence of prazosin and in the absence of α-adrenoceptor blockade. Such an action of Bay K 8644 can be reconciled with α-adrenoceptor activation causing membrane depolarization and opening of potential-operated calcium channels. It may be concluded that both α₁- and α₂-adrenoceptor-mediated contractions in human hand veins are highly dependent on Ca²⁺ influx, although the mechanisms utilized to bring about this influx partly differ between the two receptor subtypes.     

Comparison of micro-CT and cone beam CT-based assessments for relative difference of grey level distribution in a human mandible

Objectives:

The purpose of this study was to examine the ability of CT to assess the relative difference of degree of bone mineralization (grey level) parameters in a human mandible.

Methods:

Ten mandibular sections from cadavers (81.5 ± 12.1 years) were scanned using micro-CT with 27.2 μm voxel size and cone beam CT (CBCT) with 200 μm, 300 μm, and 400 μm voxel sizes. In addition, 15 clinical CBCT images from young patients (mean age 18.9 ± 3.3 years) were identified. After segmentation of bone voxels, alveolar bone and basal cortical bone regions were digitally isolated. A histogram of grey level, which is equivalent to degree of bone mineralization, was obtained from each region of the CT images. Mean, standard deviation (SD), coefficient of variation (COV), fifth percentile low (Low₅) and high (High₅) of alveolar bone and basal cortical bone regions were obtained. Percentage differences of grey level parameters between alveolar and basal cortical bones were computed.

Results:

The alveolar bone region had significantly lower Mean, Low₅ and High₅ values but significantly higher SD and COV than the basal cortical bone region for all CT images (p < 0.05). All parameters were significantly lower for the old cadaver group than for the young patient group (p < 0.05).

Conclusions:

CBCT and micro-CT provide comparable results in the assessment of relative difference in grey level distribution between alveolar and basal cortical bone regions in the human mandible. The percentage difference relative to an internal reference (basal cortical bone) can be a reliable method when assessing the degree of bone mineralization using CBCT images for both cross-sectional and longitudinal comparisons.     

Late complications of traumatic arteriovenous fistula. Case report and overview

Traumatic arteriovenous (AV) fistulas produce several profound pathophysiologic and structural changes in the circulatory dynamics of the vessels associated with the fistula. Most of the changes are reversible with surgery. However, in longstanding AV fistulas, irreversible degenerative changes occur in the arterial wall and result in dilatation and thrombosis. This can make late closure technically difficult. This report presents a case of peroneal AV fistula of 18 years duration. The diagnosis, management, and complications of long-standing AV fistulas are discussed.     

Light–dependent effects of zinc protoporphyrin IX on endothelium–dependent relaxation resistant to NoM–nitro–L–arginine

Acetylcholine (ACh) induces an Nω–nitro–L–arginine (L–NOARG)–resistant relaxation and hyperpolarization in the rat isolated hepatic artery. The possibility that carbon monoxide (CO) produced by haem oxygenase (HO) is an endogenous mediator of this response was investigated. Exogenously applied CO evoked a concentration–dependent relaxation, and the CO ‘scavenger’ oxyhaemoglobin (10μM) reduced the maximum ACh–induced relaxation by 25%. The HO inhibitor zinc protoporphyrin IX (ZnPP, 10 μM virtually abolished the ACh–induced relaxation in experiments carried out under ordinary light conditions. However, ZnPP did not affect the ACh–induced relaxation under dark conditions, even after exposure of ZnPP to intense light before the preincubation period. Biliverdin (0.1 mM), a feedback inhibitor of HO, was also inactive under dark conditions, and the HO substrate haematin (0.1 mM) did not facilitate the ACh–induced relaxation. The relaxation induced by the nitric oxide (NO) donor 3–morpholino–sydnonimin was not affected by ZnPP in the presence of light. However, ZnPP inhibited the relaxation evoked by the potassium channel opener levcromakalim and the tonic component of the contractile response to 60 mM potassium, indicating that ZnPP has effects distinct from HO inhibition in the presence of light. ZnPP should therefore be protected from light when used to inhibit HO–mediated CO formation. The results do not suggest that CO generated by HO mediates the endothelium–dependent, L–NOARG–resistant relaxation induced by ACh in the rat hepatic artery.