RESUMO
There is a trend towards increased perioperative bleeding in patients with plasma fibrinogen levels < 200 mg/dL-1. This study aimed to assess whether there is an association between preoperative fibrinogen levels and perioperative blood-product transfusion up to 48 h after major orthopedic surgery. This cohort study included 195 patients who underwent primary or revision hip arthroplasty for nontraumatic etiologies. Plasma fibrinogen, blood count, coagulation tests, and platelet count were measured preoperatively. A plasma fibrinogen level of 200 mg/dL-1 was the cutoff value used to predict blood transfusion. The mean (SD) plasma fibrinogen level was 325 (83) mg/dL-1. Only thirteen patients had levels < 200 mg/dL-1, and only one of them received a blood transfusion, with an absolute risk of 7.69% (1/13; 95%CI: 1.37-33.31%). Preoperative plasma fibrinogen levels were not associated with the need for blood transfusion (p = 0.745). The sensitivity and the positive predictive value of plasma fibrinogen < 200 mg/dL-1 as a predictor of blood transfusion were 4.17% (95%CI: 0.11-21.12%) and 7.69% (95%CI: 1.12-37.99%), respectively. Test accuracy was 82.05% (95%CI: 75.93-87.17%), but positive and negative likelihood ratios were poor. Therefore, preoperative plasma fibrinogen level in hip-arthroplasty patients was not associated with the need for blood-product transfusion.
RESUMO
Some properties of the volatile anesthetics, such as vasodilatation and myocardial depression, combined with the sympathetic inhibition that alpha2-agonists can produce, may determine hemodynamic alterations during aortic surgery. The interaction between dexmedetomidine (DEX), an alpha2-agonist, and sevoflurane during aortic surgery is unknown. We studied the effects of DEX on hemodynamics and systemic oxygenation during aortic cross-clamping (Aox) and unclamping (UAox) in sevoflurane-anesthetized dogs. Twenty dogs were anesthetized with sevoflurane and were randomly assigned to two groups prior to Aox and UAox: control, n = 10, received saline infusion only, and DEX (1 microg x kg(-1) load followed by 1 microg x kg(-1) x h(-1) infusion), n = 10. Hemodynamic and oxygenation variables were measured at baseline, after saline or DEX loading dose, 20 and 40 min after Aox, and 20 and 40 min after UAox. After DEX administration, heart rate, cardiac index (CI) and systemic oxygen transport index (DO(2)I) were lower than in control group. Aox increased mean arterial pressure (MAP) and systemic vascular resistance index (SVRI) in both groups, but the effects were greater with DEX. CI, heart rate, and DO(2)I were lower, while central venous pressure (CVP) and pulmonary artery occlusion pressure were higher in DEX compared to control. After UAox, MAP, CVP and SVRI were maintained higher in DEX in relation to control. We conclude that in sevoflurane-anesthetized dogs DEX alters the cardiovascular response during aortic surgery.