[Blood pressure monitoring - Status quo and future : A contribution to the personalized medicine]. / Blutdruckmonitoring ­ Status quo und Ausblick : Ein Beitrag zur personalisierten Medizin.

Sustainment of life demands that the heart create sufficient pressure to maintain enough flow to keep the body healthy and oxygenated. Blood pressures can be easily measured, while volume measurements required additional invasive procedures. In analogy to volumetrically determined ejection fraction, a pressure ejection fraction EF(P) may be calculated. When standardized to heart rate and body surface area, a new, effective performance metric may be defined. These metrics enable the long-term monitoring of the critically ill patient. When presented in a performance diagram, the metrics contain prognostic implications and enable a real-time evaluation of the efficacy of therapeutic measures. Until now, pressure-related prognostic statements were based on statistical averages, which by definition apply to groups. With this new analytical approach, we have the ability to provide patient-specific therapeutics in an area of medicine that requires individualized treatment. Here, we show preliminary results of applying a mathematical risk analysis to blood pressure metrics to assess therapeutic risk.

Ejection fractions and pressure-heart rate product to evaluate cardiac efficiency. Continuous, real-time diagnosis using blood pressure and heart rate.

INTRODUCTION: Ejection fractions, derived from ventricular volumes, and double product, related to myocardial oxygen consumption, are important diagnostic parameters, as they describe the efficiency with which oxygen is consumed. Present technology often allows only intermittent determination of physiological status. This deficiency may be overcome if ejection fractions and myocardial oxygen consumption could be determined from continuous blood pressure and heart rate measurements. The purpose of this study is to determine the viability of pressure-derived ejection fractions and pressure-heart rate data in a diverse patient population and the use of ejection fractions to monitor patient safety. METHODS: Volume ejection fractions, derived from ventricular volumes, EF(V), are defined by the ratio of the difference of end-diastolic volume, EDV, and end-systolic volume, ESV, to EDV. In analogy, pressure ejection fraction, EF(P), may be defined by the ratio of the difference of systolic arterial pressure, SBP, and diastolic arterial pressure, DBP, to SBP. The pressure-heart rate (heart rate: HR) is given by the product of systolic pressure and heart rate, SBP × HR. EF(P) and SBP × HR data were derived for all patients (n = 824) who were admitted in 2008 to the ICU of a university hospital at the specific time 30 min prior to leaving the ICU whether as survivors or non-survivors. The results are displayed in an efficiency/pressure-heart rate diagram. RESULTS: The efficiency/pressure-heart rate diagram reveals one subarea populated exclusively by survivors, another subarea populated statistically significant by non-survivors, and a third area shared by survivors and non-survivors. DISCUSSION AND CONCLUSION: The efficiency/pressure-heart rate product relationship may be used as an outcome criterion to assess survival and to noninvasively monitor improvement or deterioration in real time to improve safety in patients with diverse dysfunctions.

Changes in electrocardiographic morphology reflect instantaneous changes in left ventricular volume and output in cardiac surgery patients.

We examined the relation between changes in R-to-T wave amplitude ratios (R:T) and left ventricular (LV) performance as cardiac output was rapidly varied by inferior vena caval occlusion in 6 subjects prior to cardiopulmonary bypass. To assess the influence of contractility, paired studies before and after bypass were performed in 4 subjects. Stroke volume and cardiac output were assessed by aortic flow probe, and transesophageal echocardiographic LV area measures using the automated border-detection method were used to give LV stroke area, stroke force, maximal LV area, fractional area change, end-systolic elastance, and preload recruitable stroke force. Data were collected on computer and analyzed by linear regression. Significant changes in R:T and measured LV variables during the inferior vena caval occlusion were stroke volume (r = 0.81), LV stroke area (r = 0.77), LV stroke force (r = 0.81), maximal LV area (r = 0.78), and cardiac output (r = 0.80). However, R:T varied inconsistently in relation to fractional area change. After cardiopulmonary bypass, the linear relation between R:T with LV stroke force, LV stroke volume, and maximal LV area persisted, but at a lesser slope. Although absolute pre-inferior vena caval occlusion R:T did not correlate with end-systolic elastance or preload recruitable stroke force, the change in the slope of these linear relations correlated well with the change in end-systolic elastance after surgery (r = 0.92). Instantaneous changes in electrocardiographic morphology reflect changes in LV preload-dependent variables, whereas long-term changes in electrocardiographic morphology may also reflect changes in contractile state.

Evaluation of right ventricular function by assessment of cardiac efficiency: influence of induction of anaesthesia in coronary artery bypass grafting patients.

Considering the heart as a physical pump cardiac efficiency is calculated from the ratio of cardiac work performed to the maximum level of energy of the heart. The aim of the study was to compare cardiac efficiency with cardiac output and right ventricular ejection fraction. Nine patients scheduled for coronary artery bypass grafting were investigated. A femoral arterial and a right ventricular ejection fraction pulmonary artery catheter were placed in the awake state. Anaesthesia was induced with eltanolone and fentanyl. Cardiac output, pulmonary artery and central venous pressures, and right ventricular ejection fraction were measured in the awake state (baseline), 2 min after induction of anaesthesia and 1 and 5 min after intubation. Cardiac efficiency was calculated by dividing the stroke work by the maximum energy of the heart as calculated from the pressure volume diagram. An analysis of variance was carried out for cardiac efficiency, cardiac output and right ventricular ejection fraction. Cardiac efficiency was significantly (p < 0.05) reduced 1 min after intubation from 28 +/- 11 to 14 +/- 5%. In contrast the right ventricular ejection fraction (from 48 +/- 10 to 35 +/- 13%) and cardiac output (from 6.5 +/- 1.5 to 5.3 +/- 1.2 L/min) did not change significantly during the induction of anaesthesia. Cardiac efficiency was found to be a more sensitive parameter to describe changes in the right ventricular function than the ejection fraction and cardiac output during induction of anaesthesia with eltanolone and fentanyl which was used as a model to vary cardiac performance and afterload.

Ion migration through cell membranes: is it a process of diffusing corpuscles or diffracted ion matterwaves?

Justifications are presented for treating the process of ion migration through cell membranes not as a process of diffusing corpuscles but as a process of ion matterwaves being diffracted or reflected at the membrane corresponding to a permeable or an impermeable membrane. A qualitative explanation of the actions of anesthetics is given using the wave mechanical concept.