Measuring skin perfusion

• US 4,608,990 A
• Filed: 09/12/1983
• Issued: 09/02/1986
• Est. Priority Date: 09/12/1983
• Status: Expired due to Term

• Current Assignee: Virgil B. Elings
• Original Assignee: Virgil B. Elings
• Inventors: Elings, Virgil B.
• Primary Examiner(s): Doll, John
• Assistant Examiner(s): Johnson, Lance
• Application Number:
  US06/531,270
• Time in Patent Office: 1,086 Days
• Field of Search: 128/666, 128/633, 128/654, 128/691
• US Class Current: 600/317
• CPC Class Codes: A61B 5/0059 using light, e.g. diagnosis by transillumination, diascopy, fluorescence A61B5/0093, A61B5/1455, A61B5/02416 and A61B5/0261 take precedence
• CPC Class Codes: A61B 5/0275 using tracers, e.g. dye dilution
• CPC Class Codes: A61B 5/413 Monitoring transplanted tissue or organ, e.g. for possible rejection reactions after a transplant
• CPC Class Codes: G01N 21/6428 Measuring fluorescence of fluorescent products of reactions or of fluorochrome labelled reactive substances, e.g. measuring quenching effects, using measuring "optrodes" in vivo A61B5/00; immunoassay G01N33/53

Abstract

A fluorometer and method of fluorometry for illuminating an area containing fluorescent material which material fluoresces when excited with light energy at first particular frequencies and for collecting and measuring fluorescent light energy at second particular frequencies produced at the area, including, a light source for producing light energy including light energy at the first particular frequencies and with the light source having a wattage rating of no more than twenty (20) watts, pulsing the light energy at a frequency of approximately at least 10 Hz, filtering the pulsing light energy from the light source to pass substantially only the light energy at the first particular frequencies, directing the filtered pulsing light energy to the area containing fluorescent material, collecting light energy including fluorescent light energy at the second particular frequencies produced at the area and directing the collected light energy away from the area, filtering the collected light energy to pass substantially only the collected light energy at the second particular frequencies, detecting the filtered collected light energy for producing a first signal in accordance with the filtered collected light energy, and phase detecting the first signal for producing a second signal in accordance with the first signal and representative of the filtered collected light energy in phase with the filtered pulsing light energy which second signal is representative of the fluorescent light energy at the second particular frequencies produced at the area.

Claims

1. A method of measuring local blood flow in skin tissue using fluorescent dye dilution, including the following steps:

injecting a fluorescent dye solution into the blood stream,

producing light energy from a light source including light energy at first particular frequencies and with the light sources having a wattage rating of no more than twenty (20) watts,

pulsing the light energy, filtering the pulsing light energy from the light source to pass substantially only the light energy at the first particular frequencies,

directing the filtered pulsing light energy to a portion of the skin tissue containing fluorescent material,

collecting light energy including fluorescent light energy at second particular frequencies produced at the portion of the local area and directing the collected light energy away from the skin tissue,

filtering the collected light energy to pass substantially only the collected light energy at the second particular frequencies,

producing a first signal in accordance with the filtered collected light energy,

producing a second signal in accordance with the first signal and representative of the filtered collected light energy in phase with the filtered pulsing light energy which second signal is representative of the fluorescent light energy at the second particular frequencies produced at the portion of the skin tissue, and

using the magnitude of the second signal as a measure of the relative blood perfusion in the skin tissue.

2. The method of claim 1 wherein the step of pulsing the light energy provides pulsing at a frequency of approximately ten (10) Hz.