Can we trust the direct radial artery pressure immediately following cardiopulmonary bypass?

Reversal of the usual relationship between aortic and radial artery pressure can occur in patients following cardiopulmonary bypass. Radial systolic (and often radial mean) pressures were lower, relative to aortic pressure, after cardiopulmonary bypass than before bypass in all 18 patients studied. The systolic pressure difference (aortic minus radial) was large enough to be of clinical concern (12-32 mmHg) in 13 patients. The change persisted for 10-60 min, gradually returning toward normal. The change temporally was associated with warming at the end of cardiopulmonary bypass and lowered forearm vascular resistance. Relative forearm vascular resistance (x) predicted the systolic aortic minus radial pressure difference (y) by the equation y = -0.34x + 17 for all patients (r = -0.49, P less than 0.001). The authors conclude that radial artery pressure does not accurately reflect central aortic pressure in the immediate postbypass period.

The effect of Fluosol-DA on induction of inhalation anesthesia.

The liquid/gas partition coefficients of three inhalation anesthetics in Fluosol-DA 20% (Fluosol), a perfluorocarbon blood substitute, were determined in vitro. The high values found (6.68 for halothane, 7.54 for enflurane, and 7.20 for isoflurane) suggested that induction with these agents would be prolonged in patients treated with Fluosol. Induction of isoflurane anesthesia (as a representative agent) at constant inspired concentration was studied in five mongrel dogs before and after replacement of about 25% of each animal's blood volume with Fluosol. Inspired and end-tidal isoflurane and carbon dioxide concentrations were recorded breath by breath, together with cardiac output. There was a significant delay in rise of end-tidal isoflurane concentration after Fluosol infusion. However, because cardiac output could not be held constant during each experiment, and because cardiac output also affects the rate of rise of alveolar anesthetic concentration, a physiological computer model was used to compare the isoflurane blood/gas partition coefficients that must have existed to account for the observed end-tidal levels before and after Fluosol infusion, while taking cardiac output variation into account. Post-Fluosol blood/gas partition coefficients calculated in this way (2.59 +/- 0.51 SD) were significantly different (P less than 0.001) from pre-Fluosol levels (1.45 +/- 0.15 SD) and were not significantly different from post-Fluosol partition coefficients calculated by volume-weighted averaging (2.91 +/- 0.36 SD). This indicates that the delay observed was attributable in large part to increased solubility of isoflurane in blood after addition of Fluosol. Based on their similar liquid/gas partition coefficients in Fluosol, similar delays should occur with halothane and enflurane.

Arterial and venous dilation by nitroprusside and nitroglycerin--is there a difference?

Whole-body arterial and venous dilating properties of nitroprusside and nitroglycerin were compared with each other in 20 adult patients during cardiopulmonary bypass for coronary artery bypass or valvular heart surgery and were compared with simultaneous forearm vascular measurements. Nitroprusside was found to be a more effective whole-body arterial vasodilator and nitroglycerin a better whole-body venous vasodilator when each drug was infused at rates of 1.5 and 2.0 microgram/kg/min. No difference in whole-body vasodilation between the two drugs was found at 1.0 microgram/kg/min. Forearm plethysmography did not distinguish between the two drugs at any dose level.

Anaesthesia for open-heart surgery in haemodialysis-dependent patients: a report of two cases.

Two cases are presented in which patients in chronic renal failure underwent successful open heart surgery. The additional problems chronic renal failure imposes on the anaesthetic management of patients requiring cardiac surgery are discussed, with recommendations on choice of agents and techniques.

Antibody coated gold particles containing radioactive gold in the demonstration of cell surface molecules.

Gold particles of varying size which contain either 195Au of 198Au were prepared using white phosphorus or sodium citrate as the reducing agent. After coating with specific antibody to blood group A antigen or human IgG, these particles were used to determine the number of particles binding to the surface of A1 RBC's or rat RBC's to which human IgG had been attached. The number of particles binding to the surface of cells correlated with the number of antibody coated gold particles in the fluid bathing the cells as well as the number of antigen molecules on the cell surface. That is, the number of particles binding increased as the particle density of the suspension increased and as the cell surface antigen density increased. Under the conditions of the experiments, both blood group A antigen and human IgG appeared to be randomly distributed over the surface of the cells in TEM and SEM preparations. This approach permitted the quantitation of the number of gold particles bound per cell and at the same time, the examination of the distribution of the particles over the surface of the same cell population by TEM and SEM.

Comparison of the cardiovascular effects of bolus v. incremental administration of thiopentone.

Twenty unpremedicated patients (ASA grade I) were assigned randomly to receive thiopentone in 50-mg increments every 15 s until loss of lash reflex (group I) or as a 4-mg kg-1 bolus (group II). Arterial pressure, heart rate, systolic time intervals and end-tidal carbon dioxide were measured in the control state and then every 30 s. The mean dose of thiopentone in group I was 5.58 +/- 1.24 (SD) mg kg-1 which was significantly larger than in group II (P less than 0.001). Both groups exhibited similar decreases in arterial pressure and increases in heart rates. The degree of cardiac depression revealed from measurement of the systolic time intervals, indexed for heart rate, was equal in the two groups.

Influence of altering total body sodium on angiotensin I systemic converting activity (38573)

Studies were carried out in the dog to determine the extent to which alterations in total body sodium influence the systemic conversion of angiotensin 1. When the animals were maintained on a high salt diet and DOCA, conversion of angiotensin I increased signifcantly and returned to control levels when a normal salt diet was provided. When another group of animals were provided a low salt diet and mercuhydrin, angiotensin I conversion decreased significantly, although returning the animals to a normal salt diet had no further influence upon conversion. These experiments indicate that there is a direct relationship between total body sodium and the systemic conversion angiotensin 1.