Apparent dye-dilution curves produced by injection of transparent solutions

Abstract

In studies on dogs, blood was sampled as for the recording of dye-dilution curves through monochromatic densitometers. Injection of hypertonic media into the superior vena cava caused transient increases in the optical density of blood in the pulmonary and femoral arteries so as to produce apparent “dye” curves. The injection of hypotonic and hemolyzing media produced negative deflections, representing decreases in the optical density of blood, as did brief ventilation with 5% and 50% carbon dioxide in oxygen. Similar changes were demonstrated in vitro. They were compensated for in vivo by the use of a dichromatic densitometer. The changes observed are attributed to altered physical properties of the erythrocytes, which consequently change their light-transmitting and light-reflecting characteristics. Such nonspecific changes in the optical density of blood may constitute an important source of error in monochromatic densitometry done on whole blood. Submitted on January 11, 1961

Optical Artifacts in Whole Blood Densitometry: A Review of Undesirable Optical Signals, Nonspecific Effects, Encountered during Measurements of Oxygen Saturation and Dye Dilution Curves by Light Transmission

“…Associated with this decrease in size of the cells, a decrease in light transmission is observed [21], concomitantly with an increase in light reflection ( fig. 2 c) [27, 281.…”

“…Thus, the red blood cells are responsible for most of the light absorption in whole blood. These nonspecific and hence undesirable effects are due to variations in total red cell concentrations from subject to subject, variations in rate of blood flow, changes in red cell size and shape due to changes in temperature, GO2 tension and pH, and tonicity of the plasma [21]. In addition, variations in structure, pigmentation and thickness of the earpinna [25,26] are also of importance for earpiece oximetry and densitometry.…”

Measurement of cardiac output in man with a nonrecirculating indicator

“…Arterial blood was sampled with a Gilford Model 103-IR cuvette densitometer'1 using rates of withdrawal of 23 or 46 ml/ min. The densitometer was calibrated using the patient's own blood by the method outlined by Sinclair, Sutterer, Fox, and Wood (8). Each calibration curve included a minimum of two points in addition to zero.…”

Indicator-Dilution Measurement of Cardiac Output with Dissolved Hydrogen

“…Short catheters were inserted into the inferior vena cava and lower abdominal aorta. A 7F catheter was positioned fluoroscopically in the main pulmonary artery, and an 8F closed-tip Shirey catheter 8 was inserted into the right carotid artery and manipulated retrograde into the left atrium. Constant-rate injection H 2 outputs utilized the catheters in the inferior vena cava and pulmonary artery for right heart outputs and the catheters in the left atrium and aorta for left heart outputs.…”