Automatic blood pressure measuring device and method with cuff size determination

• US 5,022,403 A
• Filed: 03/11/1987
• Issued: 06/11/1991
• Est. Priority Date: 03/11/1987
• Status: Expired due to Term

• Current Assignee: Cas Medical Systems Incorporated (Edwards Lifesciences Corporation)
• Original Assignee: Cas Medical Systems Incorporated (Edwards Lifesciences Corporation)
• Inventors: LaViola, John
• Primary Examiner(s): Pellegrino, Stephen C.
• Assistant Examiner(s): SHAY, DAVID M
• Application Number:
  US07/024,662
• Time in Patent Office: 1,553 Days
• Field of Search: 128/672, 128/677, 128/680, 128/681, 128/682, 128/685
• US Class Current: 600/493
• CPC Class Codes: A61B 5/0235 Valves specially adapted therefor

Abstract

The device measures blood pressure automatically using the oscillometric technique wherein cuff pressure is deflated stepwise in dynamically determined increments while cuff pressure oscillations are sensed at each cuff pressure level and stored in a computer incorporated into the device. Stepwise cuff deflation is continued until the cuff pressure is below the subject'"'"'s diastolic pressure whereupon the cuff is automatically deflated. The device can be used with different sized cuffs specific for different patient categories. For example, the device can employ an adult cuff, or a pediatric cuff. To accomodate the different cuff sizes, the device has more than one bleed orifice with which it controls the deflation steps. The onboard computer is programmed to use a selected one of the bleed orifices in the first bleed step and to use the time duration of the first bleed step to determine what size cuff is being used. Once the cuff size is determined, the proper bleed orifice designed for the determined cuff size is made operative, and the testing continues. This minimizes the effects of cuff pressure on the arm, and the selection gives the most efficient deflation characteristics.

Claims

1. An automatic blood pressure measuring device of the non-invasive oscillometric type, said device comprising:

(a) a cuff (for girdling an appendage of a subject whose blood pressure is to be measured);

(b) pump means operably connected to said cuff for inflating the latter;

(c) first and second valve means operably connected to said cuff for bleeding air therefrom in stepwise fashion, said first valve means being (adapted for use with a pediatric size cuff), and said second valve means being (adapted for use with an adult size cuff);

(d) microprocessor means operably connected to said pump means and connected to said first and second valve means for controlling operation of the device, said microprocessor means being operable to initiate inflation of said cuff to a predetermine initial pressure, and said microprocessor means further being operable to activate said first valve means to deflate said cuff from said initial pressure to a first calculated lower pressure;

(e) pressure sensor means operably connected to said microprocessor means to signal said microprocessor means when said first calculated lower pressure is reached in said cuff;

(f) said microprocessor means including means to determine the lapsed time between actuation of said first valve means and reception of a signal from said pressure sensor means indicative that cuff pressure has reached said first calculated lower pressure, and said microprocessor also including means for comparing said lapsed time with a target time span; and

(g) means for closing said first valve means and opening said second valve means when said lapsed time is greater than said target time span, whereby continuation of the blood pressure measurement cycle will be via said second valve means.