Patient Monitoring

Abstract

A hemodynamic monitor and corresponding method for determining the requirement for, and if required the nature or extent of, and for monitoring the response to, an intervention by a carer for a subject in order to improve the hydration level and hemodynamic status of the subject during a period or periods of hemodynamic instability includes, firstly, a processor. The processor incorporates software arranged to continuously analyse and process a blood pressure or arterial volume/plethysmographic signal obtained from the subject in order to derive a plurality of complementary parameters throughout the monitoring of the subject. The monitor also incorporates display means displaying images representing the derived plurality of complementary parameters. The images include at least one image representing graphically at least one stress related hemodynamic parameter plotted against time to provide an immediate indication of a change in hemodynamic status and thus the requirement for an intervention. The images also include at least one image representing graphically at least one fluid responsiveness parameter plotted against time to provide an indication of the hydration level and associated ventricular pre load status of the subject to determine the nature or extent of the intervention if required. The images may also include at least one image representing graphically at least one response related parameter compared to the value of the parameter at the point of the intervention to provide an indication of the desired and/or actual response of the subject to an intervention. Trend and acute changes displays may be combined. Specific parameters providing information on the quality of the left ventricle and right heart/venous return/preload may also be derived and displayed.

1 . A hemodynamic monitor for determining the requirement for, and/or if required the nature or extent of, and/or for monitoring the response to, an intervention by a carer for a subject in order to improve the hydration level and/or hemodynamic status of the subject during a period or periods of hemodynamic instability comprising:
 (a) a processor comprising software arranged to continuously analyse and process at least a blood pressure or arterial volume/plethysmographic signal obtained from the subject in order to derive a plurality of complementary parameters throughout the monitoring of the subject   (b) display means displaying images representing the derived plurality of complementary parameters, characterised in that the images comprise:
 (1) at least one image representing graphically at least one stress related hemodynamic parameter plotted against time to provide an early/immediate indication of a change in the hemodynamic status and thus the requirement for an intervention 
 (2) at least one image representing graphically at least one fluid responsiveness parameter plotted against time to provide an indication of the hydration level and associated ventricular pre load status of the subject to determine the nature or extent of the intervention if required, wherein the intervention comprises a change in hydration level and/or use/change of any other therapeutic administered to influence the hydration and/or hemodynamic status of the subject. 
   
     
     
         2 . The hemodynamic monitor of  claim 1  further characterised in that the images comprise
 (3) at least one image representing graphically at least one response related parameter compared to the value of the parameter at the point of the intervention to provide an indication of the desired and/or actual response of the subject to an intervention.   
     
     
         3 . The hemodynamic monitor of  claim 2  further characterised in that at least one response related parameter is plotted against time with reference to an indication of the value of the parameter at the point of the intervention. 
     
     
         4 . The hemodynamic monitor of  claim 3  further characterised in that the at least one response related parameter is plotted against time relative to a baseline value of the parameter taken at the point of the intervention. 
     
     
         5 . The hemodynamic monitor of  claim 2  further characterised in that the at least one response related parameter is indicated as the absolute or percentage change compared to the value of the parameter at the point of the intervention. 
     
     
         6 . The hemodynamic monitor of  claim 1  further characterised in that the at least one stress related hemodynamic parameter and/or the at least one fluid responsiveness parameter and/or the at least one response related parameter is displayed in the form of at least one image representing current changes in the parameter in combination with at least one image representing longer term changes in the parameter auto scaled to the duration of monitoring of the subject, or scaled to any representative longer period of time, wherein the at least one image displaying current changes in the parameter comprises an expanded view of a suitable portion of the auto scaled/longer scaled image thus facilitating monitoring of current changes in the value of the parameter whilst simultaneously allowing monitoring of longer term changes in the parameter. 
     
     
         7 . The hemodynamic monitor of  claim 1  further characterised in that respiratory variation in the at least one fluid responsiveness parameter is plotted per beat to provide an indication of the stability of the right heart/venous return/preload signal. 
     
     
         8 . The hemodynamic monitor of  claim 1  further characterised in that the display means displays at least one image representing the blood pressure signal obtained from the subject to provide an indication of the stability of the left ventricle signal. 
     
     
         9 . The hemodynamic monitor of  claim 1  further characterised in that the at least one image representing graphically at least one stress related hemodynamic parameter and/or at least one fluid responsiveness parameter and/or at least one response related parameter incorporates a target zone representing an acceptable value or range of values for the at least one parameter. 
     
     
         10 . The hemodynamic monitor  claim 1  further characterised in that the at least one stress related hemodynamic parameter is displayed in an upper portion of the display means and the at least one fluid responsiveness parameter is displayed in a central or lower portion of the display means depending upon whether at least one response related parameter is also displayed, wherein if at least one response related parameter is also displayed it is displayed in a central or lower portion of the display means. 
     
     
         11 . The hemodynamic monitor of  claim 1  further characterised in that the display means displays images representing graphically a plurality of stress related hemodynamic parameters plotted against time to provide an early/immediate indication of a change in the hemodynamic status and thus the requirement for an intervention and/or display means displays images representing graphically a plurality of fluid responsiveness parameters plotted against time to provide an indication of the hydration level and/or associated ventricular pre load status of the subject and/or displays images representing graphically a plurality of response related parameters plotted against time to provide an early/immediate indication of the desired and/or actual response of the subject to the intervention. 
     
     
         12 . The hemodynamic monitor of  claim 11  further characterised in that the images representing graphically the plurality of stress related hemodynamic parameters plotted against time and/or the images representing graphically the plurality of fluid responsiveness parameters plotted against time and/or the images representing response related parameters plotted against time are displayed in defined groupings. 
     
     
         13 . The hemodynamic monitor of  claim 1  wherein the at least one stress related hemodynamic parameter is selected from mean arterial pressure, systolic pressure, diastolic pressure, heart rate, stroke volume, cardiac output, systemic vascular resistance, respiratory changes in pressure or stroke volume, oxygen delivery and related parameters indexed to take account of the body surface area of the subject. 
     
     
         14 . The hemodynamic monitor of  claim 1  wherein the at least one fluid responsiveness parameter is selected from stroke volume variation (SVV), pulse pressure variation (PPV), systolic pressure variation (SPV), mean blood flow during a passive leg raising procedure (PLR) and pulse oximety plethysmographic waveform amplitude. 
     
     
         15 . The hemodynamic monitor of  claim 2  wherein the at least one response related parameter comprises stroke volume response to the intervention. 
     
     
         16 . A method of determining the requirement for, and/or if required the nature or extent of, and/or for monitoring the response to, an intervention by a carer for a subject in order to improve the hydration level and/or hemodynamic status of the subject during a period or periods of hemodynamic instability comprising:
 (a) continuously analysing and processing at least a blood pressure or arterial volume/plethysmographic signal obtained from the subject using a processor comprising software arranged to derive a plurality of complementary parameters throughout the monitoring of the subject   (b) displaying images on a display means representing the derived plurality of complementary parameters, characterised in that the images comprise:
 (1) at least one image representing graphically at least one stress related hemodynamic parameter plotted against time to provide an early/immediate indication of a change in the hemodynamic status and thus the requirement for an intervention 
 (2) at least one image representing graphically at least one fluid responsiveness parameter plotted against time to provide an indication of the hydration level and associated ventricular pre load status to determine the nature or extent of the intervention if required, wherein the intervention comprises a change in hydration level and/or use/change of any other therapeutic administered to influence the hydration and/or hemodynamic status of the subject. 
   
     
     
         17 . The method of  claim 16  further characterised in that the images comprise
 (3) at least one image representing graphically at least one response related parameter compared to the value of the parameter at the point of the intervention to provide an indication of the desired and/or actual response of the subject to an intervention.   
     
     
         18 . The method of  claim 17  further characterised in that at least one response related parameter is plotted against time with reference to an indication of the value of the parameter at the point of the intervention. 
     
     
         19 . The method of  claim 18  further characterised in that the at least one response related parameter is plotted against time relative to a baseline value of the parameter taken at the point of the intervention. 
     
     
         20 . The method of  claim 17  further characterised in that the at least one response related parameter is indicated as the absolute or percentage change compared to the value of the parameter at the point of the intervention. 
     
     
         21 . The method of  claim 16  further characterised in that the at least one stress related hemodynamic parameter and/or the at least one fluid responsiveness parameter and/or the at least one response related parameter is displayed in the form of at least one image representing current changes in the parameter in combination with at least one image representing longer term changes in the parameter auto scaled to the duration of monitoring of the subject, or scaled to any representative longer period of time, wherein the at least one image displaying current changes in the parameter comprises an expanded view of a suitable portion of the auto scaled/longer scaled image thus facilitating monitoring of current changes in the value of the parameter whilst simultaneously allowing monitoring of longer term changes in the parameter. 
     
     
         22 . The method of  claim 16  further characterised in that respiratory variation in the at least one fluid responsiveness parameter is plotted per beat to provide an indication of the stability of the right heart/venous return signal. 
     
     
         23 . The method of  claim 16  further characterised in that at least one image representing the blood pressure signal obtained from the subject to provide an indication of the stability of the left heart signal is displayed on the display means. 
     
     
         24 . The method of  claim 16  further characterised in that the at least one image representing graphically at least one stress related hemodynamic parameter and/or at least one fluid responsiveness parameter and/or at least one response related parameter incorporates a target zone representing an acceptable value or range of values for the at least one parameter. 
     
     
         25 . The method of  claim 16  further characterised in that the at least one stress related hemodynamic parameter is displayed in an upper portion of the display means and the at least one fluid responsiveness parameter is displayed in a central or lower portion of the display means depending upon whether at least one response related parameter is also displayed, wherein if at least one response related parameter is also displayed it is displayed in a central or lower portion of the display means. 
     
     
         26 . The method of  claim 16  further characterised in that images representing graphically a plurality of stress related hemodynamic parameters plotted against time to provide an early/immediate indication of a change in the hemodynamic status and thus the requirement for an intervention and/or images representing graphically a plurality of fluid responsiveness parameters plotted against time to provide an indication of the hydration level and/or associated ventricular pre load status of the subject and/or images representing graphically a plurality of response related parameters plotted against time to provide an early/immediate indication of the desired and/or actual response of the subject to the intervention are displayed by the display means. 
     
     
         27 . The method of  claim 26  further characterised in that the images representing graphically the plurality of stress related hemodynamic parameters plotted against time and/or the images representing graphically the plurality of fluid responsiveness parameters plotted against time and/or the images representing response related parameters plotted against time are displayed in defined groupings. 
     
     
         28 . The method of  claim 16  wherein the at least one stress related hemodynamic parameter is selected from mean arterial pressure, systolic pressure, diastolic pressure, heart rate, stroke volume, cardiac output, systemic vascular resistance, respiratory changes in pressure or stroke volume, oxygen delivery and related parameters indexed to take account of the body surface area of the subject. 
     
     
         29 . The method of  claims 16  wherein the at least one fluid responsiveness parameter is selected from stroke volume variation (SVV), pulse pressure variation (PPV), systolic pressure variation (SPV), mean blood flow during a passive leg raising procedure (PLR) and pulse oximety plethysmographic waveform amplitude. 
     
     
         30 . The method of  claim 17  wherein the at least one response related parameter comprises stroke volume response to the intervention.