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Compliance or failure and improvement or deterioration diagnosis of patients from performance diagrams

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Introduction

Blood pressure and heart rate data displayed in a performance diagram (PD) may diagnose accurately compliance or failure and improvement or deterioration while traditional hemodynamics would indicate a patient to be stable.

Materials and methods

A PD plots the parameters pressure efficiency (EF[P]) versus time in an upper graph and arterial pulse pressure (PP*), systolic pressure (SBP*), and diastolic pressure (DBP*) versus time in a lower graph. EF(P)=PP*/SBP* in analogy to the volume ejection fraction EF(V)=SV/EDV, where SV=stroke volume and EDV=end-diastolic volume. The asterisk (*) indicates conversion of events per beat into events per time and standardization to body surface area (BSA), f. e., PP*=(PPxHR)/BSA, analogous to the conversion of SV to cardiac index (CI), where CI=(SV*HR)/BSA. PDs suggest: (1) compliance when all parameters equal or exceed normal values (N), (2) failure without immediate danger of death when normal values of EF(P), or SBP*, or DBP* are not maintained, (3) failure with immediate danger of death (critical illness), when normal PP* is not maintained, (4) deterioration or improvement when the trend of two successive measurements departs from, or points towards, the normal values. Data from 213 patients were retrospectively analyzed using standard statistical methods including sensitivity and specificity determinations, binomial scoring, and t-testing.

Results

Based on statistical analysis, PDs predicted compliance and failure with a sensitivity of 94% and a specificity of 84%. PDs also predicted improvement and deterioration at P<0.01. As illustrated in the figures, traditional hemodynamics diagnoses a patient as stable as late as 10 min before the occurrence of flash edema. The PD diagnoses a failing and deteriorating patient as early as 2.5 h prior to occurrence of flash edema and diagnoses the patient as critically ill 25 min prior to the occurrence of the flash edema.

Discussion

This study suggests utility of PDs in accurately diagnosing compliance or failure which would allow early intervention and monitoring of the effects of intervention in real time as compared to traditional hemodynamic evaluation.

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Keywords

  • Stroke Volume
  • Cardiac Index
  • Body Surface Area
  • Critical Illness
  • Arterial Pulse