Method for measuring blood pressure and apparatus for automated blood pressure measuring

• US 4,926,873 A
• Filed: 03/20/1989
• Issued: 05/22/1990
• Est. Priority Date: 08/01/1988
• Status: Expired due to Term

• Current Assignee: Koninklijke Philips N.V.
• Original Assignee: Hewlett-Packard Company (HP Inc.)
• Inventors: Frankenreiter, Michael
• Primary Examiner(s): Sykes, Angela D.
• Application Number:
  US07/325,627
• Time in Patent Office: 428 Days
• Field of Search: 128/672, 128/677-686
• US Class Current: 600/494
• CPC Class Codes: A61B 5/02116 of pulse wave amplitude A61B5/02225 takes precedence
• CPC Class Codes: A61B 5/022 by applying pressure to close blood vessels, e.g. against the skin; Ophthalmodynamometers
• CPC Class Codes: A61B 5/02225 using the oscillometric method

Abstract

A method of non-invasive blood measuring is conducted according to the oscillometric method. The size of the decremental steps Δp_def of a certain measuring cycle C₁₊₁ is a function of subject'"'"'s actual blood pressure of the preceding measuring cycle c_i.

Claims

1. A method for measuring blood pressure of a subject, the method comprising the steps of:

(a) applying a blood pressure cuff about a subject'"'"'s limb that contains an artery;

(b) inflating the cuff to a pressure p_max above the systolic pressure p_sys of the subject, thereby occluding flow in the artery;

(c) reducing cuff pressure from p_max to a pressure p_min below the diastolic pressure p_dia of the subject in a sequence of cuff pressure abrupt decrements Δ

p_def of approximately equal magnitude in a sequence of time intervals, where the pressure decrement for each time interval in cycle i+1 (i≧

1) is determined by dividing the difference of two pressure values p_2ci and p_1ci by a positive constant that is independent of subject and that is no greater than six, where p_1ci and p_2ci are pressure values determined in cycle i that satisfy the relations p_min ≦

p_1ci <

p_2ci ≦

p_max, thereby permitting sequentially increasing flow of blood through the artery;

(d) determining the artery pressure within each time interval for which cuff pressure is approximately constant and determining p_sys, p_dia and the mean arterial pressure for the cycle i+1;

(e) displaying the blood pressure values p_sys and p_dia for the subject for the cycle i+1; and

(f) repeating the preceding method steps (b), (c) and (d) at least once.

2. The method of claim 1, further comprising the steps of:

choosing p_2ci as p_sys ci =systolic pressure determined in cycle i, and

choosing p_1ci as p_dia ci =diastolic pressure determined in cycle i.

3. The method of claim 1, further comprising the steps of:

providing previously-determined systolic and diastolic pressure values, denoted p_sys,0 and p_dia,0, for said subject so that, for said first cycle i=1 said pressure decrement Δ

p_def is determined by ##EQU4##

4. Apparatus for measuring blood pressure of a subject, the apparatus comprising:

an inflatable and deflatable pressure cuff that can be applied about a subject'"'"'s limb containing an artery;

pressure means for inflating the cuff to a pressure p_max above the systolic pressure p_sys of the subject;

pressure reduction means for reducing the cuff pressure from P_max to a pressure p_min below the diastolic pressure p_min of the subject in a sequence of cuff pressure abrupt decrements Δ

p_def of approximately equal magnitude in a sequence of time intervals, where the pressure decrement for each time interval in cycle i+1 (i≧

1) is determined by dividing the difference of two pressure values p_2ci and p_1ci by a positive constant that is independent of subject and that is no greater than six, where p_1ci and p_2ci are pressure values determined in cycle i that satisfy the relations p_min ≦

p_1ci <

p_2ci ≦

p_max, thereby permitting sequentially increasing flow of blood through the artery;

measurement means for determining the artery pressure within each time interval for which cuff pressure is approximately constant and for determining p_sys, p_dia and the mean arterial pressure for the cycle i+1; and

display means for displaying the blood pressure values p_sys and p_dia for the subject for cycle i+1.

5. The apparatus of claim 4, further comprising data input means for making available previously-determined systolic and diastolic pressure values, denoted p_sys,0 and p_dia,0, for said subject so that, for said first cycle i=1, said pressure decrement Δ

p_def is determined by ##EQU5##

6. The apparatus of claim 4, further comprising recycle means for causing said apparatus of claim 14 to perform two of said cycles i=1 and i=2 of blood pressure measurement.