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The ability to monitor the match between systemic oxygen delivery and consumption using mixed venous oxygen saturation is an important component of management of critically ill patients. Mixed venous oxygen saturation is a particularly useful parameter in circumstances where systemic oxygen delivery is significantly compromised, such as the acute respiratory distress syndrome. With the advent of venovenous extracorporeal life support (ECLS) in the treatment of this condition, however, accurate measurement of true mixed venous oxygen saturation has not been available, because of this artificial elevation of venous oxygen content. Using an algebraic solution, the authors developed an equation to calculate true patient mixed venous oxgen saturation during ECLS. This is accomplished using readily obtainable data such as cardiac output, ECLS flow, ECLS circuit pre and post oxygenator blood oxygen content, pulmonary arterial oxygen saturation, and patient hemoglobin. The formula has been used in an in vitro model, simulating venovenous ECLS and native venous saturation ranging from 20-72%, with a resulting correlation coefficient between calculated and measured saturation of 0.983 and a gamma intercept of 0.7. Using this new mathematical model, previously unobtainable information about the match of oxygen delivery and consumption in venovenous ECLS is now available. This information will facilitate optimal management of oxygen kinetics in patients during venovenous extracorporeal support.

This report describes the development of an implantable gas exchange device. The device is composed of hollow fiber elements wound around a central open core enclosed in a compliant outer casing, offering very low resistance to blood while providing adequate gas exchange. The purpose of this study was to determine if this device design can completely support the gas exchange requirements of a large animal when the device is placed in series with the main pulmonary artery (PA). Six 40-80 kg adult sheep were used. The device was placed with vascular grafts anastomosed end to side on the proximal and distal main PA. The study began with the entire right ventricular blood flow being diverted through the device by occlusion of a snare around the PA between the vascular grafts. Total gas exchange then was provided by the device and the endotracheal tube was clamped. Results showed that this pumpless potentially implantable device is capable of completely supporting the gas exchange requirements of the experimental animals for up to 8 hours in the acute setting without significant change in cardiac index (CI) and oxygen consumption (VO2) compared with baseline. CI = 55.0 +/- 17.0 cc/min/kg versus 45.0 +/- 17.3 cc/min/kg. VO2 = 1.90 +/- 0.96 cc O2/min/kg versus 2.08 +/- 0.54 cc O2/min/kg.

To investigate the impact of ulcerogenic drugs on surgery for the treatment of peptic ulcer disease, we reviewed 150 surgical cases. Ulcerogenic drug use (steroids and/or nonsteroidal anti-inflammatory agents, including aspirin) increased from 15% between 1972 and 1977 to 37% between 1983 and 1988. While there was no correlation between ulcerogenic drug use and hemorrhage, obstruction, or intractable pain, 16 (52%) of the 31 perforations and 26 (38%) of the 69 emergency operations were associated with use of ulcerogenic drugs. The overall mortality rate was 11%. Death was correlated with age greater than 65 years and emergency operation, but not with ulcerogenic drug use or other variables. Of 12 patients with histories of peptic ulcer disease who were treated with ulcerogenic drugs without concomitant antiulcer prophylaxis, 11 (92%) required emergency operation to treat perforation or massive hemorrhage. Standard antiulcer medications or misoprostol should be prescribed to elderly patients and to those with histories of ulcers who require ulcerogenic drug therapy.