Methods for adaptive limb occlusion
Methods for adaptive cuff inflation for the purposes of occluding a limb of a subject include inflating a cuff to a pressure at or above limb occlusion pressure and periodically deflating the cuff to detect amplitude of oscillometric oscillations reaching or exceeding a predetermined threshold, whereby indicating that the cuff pressure has reached an updated systolic blood pressure. Selecting the cuff to be wide enough to define limb occlusion pressure at or below the systolic blood pressure assures that this maneuver does not compromise cessation of blood flow to the limb. Devices are disclosed configured to operate in at least two of the following three operating modes: a tourniquet mode, a remote conditioning mode and a blood pressure monitoring mode.
1. A method for adaptive limb occlusion of a subject, the method comprising the steps of:
(a) providing a cuff sized to be placed about a limb of the subject, said cuff is configured to define a limb occlusion pressure to be equal to or below a systolic blood pressure of the subject;
(b) determining the systolic blood pressure of the subject by inflating the cuff placed about the same limb of the subject;
(c) inflating the cuff to a pressure sufficient to cause cessation of blood flow through the same limb, said pressure being below, at or above the systolic blood pressure calculated in step (b) for a period of cuff inflation, said period of cuff inflation lasting at least about one minute;
(d) at least once during the period of cuff inflation, decreasing entire cuff pressure until detecting an increase in oscillometric oscillations indicating the cuff pressure to be above, equal to, and capable of being below an updated systolic blood pressure while at least equal to or being above the corresponding limb occlusion pressure of the subject, whereby said entire cuff pressure is decreased sufficiently to determine the updated systolic blood pressure of the subject but without compromising cessation of blood flow through the same limb; and
(e) inflating the cuff to a pressure below, at or above the updated systolic blood pressure calculated in step (d), said pressure being sufficient to continue causing cessation of blood flow through the same limb.
2. The method as in claim 1 , wherein the cuff is inflated in steps (c) and (e) to the pressure at or above the limb occlusion pressure.
3. The method as in claim 1 , wherein said step (d) further including a step of decreasing cuff pressure until an amplitude of detected oscillometric oscillations increases to a predetermined threshold indicating the cuff pressure to be equal to or below the updated systolic blood pressure but at least equal to or above the corresponding limb occlusion pressure of the subject, whereby the updated systolic blood pressure is determined without compromising cessation of blood flow through the limb.
4. The method as in claim 1 , wherein said steps (d) and (e) are repeated on a scheduled basis throughout the period of cuff inflation.
5. The method as in claim 1 , wherein said steps (c) and (e) are conducted by inflating the cuff to a pressure exceeding the systolic blood pressure by a predetermined safety margin.
6. The method as in claim 1 , wherein step (a) further comprising providing a controller operably connected to said cuff, said controller is configured to automatically perform said steps (b) through (e).
7. A method for adaptive limb occlusion of a subject, the method comprises the steps of:
(a) providing a cuff placed about the limb of the subject, the cuff configured to define a limb occlusion pressure to be equal to or below a systolic blood pressure of the subject;
(b) inflating the cuff to a pressure at or above the limb occlusion pressure of the subject for a period of cuff inflation lasting at least one minute;
(c) continuously or intermittently monitoring cuff pressure for an indication that the entire cuff pressure is at or below systolic blood pressure of the subject; and
(d) upon the indication that the entire cuff pressure is at or below the systolic blood pressure of the subject and the cuff pressure is at or above the limb occlusion pressure of the subject, inflating the cuff to a pressure exceeding the limb occlusion pressure by a predetermined safety margin,
whereby maintaining cessation of blood flow to the same limb throughout the period of cuff inflation.
8. The method as in claim 7 , wherein said step (c) further including deflating said cuff at least once during said period of cuff inflation until reaching a predetermined increase in oscillometric oscillations within said cuff.
9. The method as in claim 8 , wherein in step (c) said predetermined increase in oscillometric oscillations is determined analyzing an amplitude of said oscillometric oscillations.
10. The method as in claim 9 , wherein in step (c) said predetermined increase in oscillometric oscillations is determined by detecting said amplitude reaching a predetermined amplitude threshold.
11. The method as in claim 9 , wherein in step (c) said predetermined increase in oscillometric oscillations is determined by analyzing a rate of increase of said amplitude.