Detecting gastrointestinal hypoperfusion during cardiac tamponade in pigs: a role for nitric oxide tonometry?

OBJECTIVE: To evaluate different techniques and regional approaches for detecting critical reductions in gastrointestinal (GI) perfusion. DESIGN: Laboratory, animal, controlled study. SETTING: University animal research laboratory. SUBJECTS: Thirteen anesthetized, ventilated, juvenile domestic pigs. INTERVENTIONS: Dextran was infused into the pericardial sac to achieve cardiac tamponade that reduced cardiac output to 25% of baseline value. Hemodynamics were invasively monitored, and blood gases were sampled in the systemic and portal circulations. Tonometers were placed in the corpus of the stomach and in the jejunum, 50 cm aboral to the ligament of Treitz. MEASUREMENTS AND MAIN RESULTS: We measured cardiac output, portal venous blood flow, mesenteric oxygen delivery and consumption, systemic and portal venous blood gases and acid-base balance, stomach and jejunal transepithelial potential difference, stomach and jejunal intramucosal pH, arterial plasma concentrations of asymmetric dimethylarginine, and jejunal, intraluminal nitric oxide. One hour of cardiac tamponade decreased mesenteric oxygen delivery and consumption in a linear fashion and resulted in mesenteric acidosis, as evidenced by decreases in pH, standard bicarbonate, oxygen saturation, and PO2 and increases in PCO2. The potential difference in the jejunum decreased earlier than in the stomach, whereas stomach intramucosal pH decreased before jejunal intramucosal pH. Intraluminal nitric oxide in the jejunum was markedly reduced soon after cardiac tamponade. This reduction was accompanied by an increase in arterial plasma concentrations of the endogenous nitric oxide synthase inhibitor asymmetric dimethylarginine. Investigated variables were unchanged in control animals. CONCLUSIONS: Both intramucosal pH and potential difference measurements may be used to detect critical reduction in GI perfusion. Regional and temporal differences may reduce the accuracy of these methods. Jejunal tonometry can yield an early nitric oxide measurement that indicates mesenteric low-flow conditions. Jejunal tonometry also yields quantitative information about this modulator of hemodynamic and mucosal barrier function, information that is relevant to GI failure during shock.     

Special Review: Some Recent Texts in Educational Psychology.

Reviews seven books on educational psychology. The first book reviewed is "Educational Psychology," by Glenn M. Blair R. Stewart Jones, and Ray H. Simpson (see record 1954-07938-000). The second book reviewed is "Principles of Educational Psychology," by W.D. Commins, and Barry Fagin (see record 1955-01422-000). The third book reviewed is "Educational Psychology," by Lee J. Cronbach (see record 1954-07941-000). The fourth book reviewed is "Psychology for Modern Education," by James L. Mursell (see record 1953-02945-000). The fifth book reviewed is "Introduction to Educational Psychology," by Clellen L. Morgan, H.H. Remmers, and Einer R. Ryden (see record 1954-08965-000). The sixth book reviewed is "Psychology in Teaching," by Henry P. Smith (see record 1955-01434-000). The last book reviewed is third edition of "Psychology in Education," by Herbert Sorenson (see record 1954-08966-000). Either explicitly or by implication, the authors are saying that the conceptual schemes that now hold the center of the stage in the laboratories are not, in their present stage of development, useful to them as educational psychologists, and that as a result they have had to develop and use others. (PsycINFO Database Record (c) 2010 APA, all rights reserved)