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Background and Objective Previous studies in laser assisted vascular welding have been limited by the lack of a reliable end point for tissue fusion. As a means of improving the reproductibility of laser assisted repairs, a system incorporating real time temperature monitoring and closed loop feedback was used. Study Design/Materials and Methods The system consisted of a direct view infrared thermometer for monitoring the laser heated spot, a 1.9 μm diode laser, and a microprocessor for data acquisition and feedback control of the laser power to maintain a constant tissue temperature. Rat aortas were welded under constant surface temperature conditions. Results In vivo temperature stability of ±2°C was achieved over a temperature range of 70–90°C pertinent to welding small vessels. When welds were completed using the feedback system to maintain the tissue temperature at 80°C, the acute success rate was 100% and the burst pressure was 290 ± 70 mmHg. Conclusion These studies demonstrate that the use of real time monitoring and feedback control results in improved consistency for vascular tissue welding. © 1996 Wiley‐Liss, Inc.

PurposeThe objective of this study was to demonstrate the safety and performance of a unique extracorporeal carbon dioxide removal system (Hemolung, ALung Technologies, Pittsburgh, PA) which incorporates active mixing to improve gas exchange efficiency, reduce exposure of blood to the circuit, and provide partial respiratory support at dialysis-like settings.MethodsAn animal study was conducted using eight domestic crossbred sheep, 6–18 months of age and 49–115 kg in weight. The sheep were sedated and intubated, and a 15.5-Fr dual lumen catheter was inserted into the right jugular vein. The catheter was connected to the extracorporeal circuit primed with heparinized saline, and flow immediately initiated. The animals were then awakened and encouraged to stand. The animals were supported in a stanchion and monitored around the clock. Anticoagulation was maintained with heparin to achieve an aPTT of 46–70 s.ResultsMeasurements included blood flow rate through the device, carbon dioxide exchange rate, pump speed and sweep gas flow rate. Safety and biocompatibility measurements included but were not limited to plasma-free hemoglobin, hematocrit, white blood cell count, platelet count and fibrinogen. The Hemolung removed clinically significant amounts of carbon dioxide, more than 50 ml/min, at low blood flows of 350–450 ml/min, with minimal adverse effects.ConclusionsThe results of 8-day trials in awake and standing sheep supported by the Hemolung demonstrated that this device can consistently achieve clinically relevant levels of carbon dioxide removal without failure and without significant risk of adverse reactions.

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