BACKGROUND:Traditional patient monitoring may not detect cerebral tissue hypoxia, and typical interventions may not improve tissue oxygenation. Therefore, monitoring cerebral tissue oxygen status with regional oximetry is being increasingly used by anesthesiologists and perfusionists during surgery. In this study, we evaluated absolute and trend accuracy of a new regional oximetry technology in healthy volunteers.METHODS:A near-infrared spectroscopy sensor connected to a regional oximetry system (O3TM, Masimo, Irvine, CA) was placed on the subject’s forehead, to provide continuous measurement of regional oxygen saturation (rSo2). Reference blood samples were taken from the radial artery and internal jugular bulb vein, at baseline and after a series of increasingly hypoxic states induced by altering the inspired oxygen concentration while maintaining normocapnic arterial carbon dioxide pressure (Paco2). Absolute and trend accuracy of the regional oximetry system was determined by comparing rSo2 against reference cerebral oxygen saturation (Savo2), that is calculated by combining arterial and venous saturations of oxygen in the blood samples.RESULTS:Twenty-seven subjects were enrolled. Bias (test method mean error), standard deviation of error, standard error of the mean, and root mean square accuracy (ARMS) of rSo2 compared to Savo2 were 0.4%, 4.0%, 0.3%, and 4.0%, respectively. The limits of agreement were 8.4% (95% confidence interval, 7.6%–9.3%) to −7.6% (95% confidence interval, −8.4% to −6.7%). Trend accuracy analysis yielded a relative mean error of 0%, with a standard deviation of 2.1%, a standard error of 0.1%, and an ARMS of 2.1%. Multiple regression analysis showed that age and skin color did not affect the bias (all P > 0.1).CONCLUSIONS:Masimo O3 regional oximetry provided absolute root-mean-squared error of 4% and relative root-mean-squared error of 2.1% in healthy volunteers undergoing controlled hypoxia.

Hypoxia has been proposed to enhance, diminish, or have no effect on laboratory measures of coagulation or clinical thrombosis. Further, there usually are significant pathological or environmental factors concurrently present with hypoxia. Thus, the goal of the present investigation was to determine whether whole blood or plasmatic coagulation and fibrinolytic kinetics would change in response to progressive hypoxia to a systemic oxygenation (SpO2) of 70%. Healthy, conscious volunteers (n = 9) breathing a hypoxic mixture of gases during an in-vivo validation of noninvasive cerebral oximetry had blood samples collected and assessed with thrombelastography at normoxia and after SpO2 of 70%. A mild release of endogenous heparin-like activity occurred that diminished plasmatic coagulation, and a mild increase in clot lysis time also was noted. Further investigation to determine whether these phenomena occur in more chronic, less hypoxic states as sources of hypocoagulation or thrombophilia is needed.

Left ventricular assist devices (LVADs) are commonly used as either a bridge-to-transplant or a destination therapy. The traditional approach for LVAD implantation is via median sternotomy, but many candidates for this procedure have a history of failed cardiac surgeries and previous sternotomy. Redo sternotomy increases the risk of heart surgery, particularly in the setting of advanced heart failure. Robotics facilitates a less invasive approach to LVAD implantation that circumvents some of the morbidity associated with a redo sternotomy. We compared the outcomes of all patients at our institution who underwent LVAD implantation via either a traditional sternotomy or using robotic assistance. The robotic cohort showed reduced resource utilization including length of hospital stay and use of blood products. As the appropriate candidates become elucidated, robotic assistance may improve the safety and cost-effectiveness of reoperative LVAD surgery.

Left ventricular assist devices are increasingly important in the management of advanced heart failure. Most patients who benefit from these devices have had some prior cardiac surgery, making implantation of higher risk. This is especially true in patients who have had prior pectoralis flap reconstruction after sternectomy for mediastinitis. We outline the course of such a patient, in whom the use of robotic assistance allowed for a less invasive device implantation approach with preservation of the flap for transplantation.

While topical thrombin application can markedly improve surgical hemostasis, rapid absorption of thrombin can result in pulmonary embolism and death. We report a case of accidental interstitial infiltration of topical thrombin after hemorrhoidectomy that was treated with administration of human antithrombin and heparin anticoagulation. Except for a marked decrease in antithrombin activity from super normal to normal values, the patient exhibited no laboratory or clinical signs of pulmonary embolism, thrombin mediated consumptive loss of procoagulants, or regional thrombosis. The patient had an uncomplicated recovery without sign of thrombotic morbidity. While it is hoped that such a medical misadventure should not occur, our case may serve as a reference to guide anticoagulant therapy if such a clinical scenario arises.