The evaluation of haemodynamic changes is still challenging in clinically relevant situations (e.g. in bleeding, septic and postoperative patients) with the conventional monitoring routinely used including heart rate and mean arterial pressure. If the arterial pressure drops and the heart increases, the haemodynamic state is already decompensated and a therapy is at risk being indicated too late.

Prior to decompensation - still in the state of compensated shock - it would be desirable to detect the shock already. The compensated shock is characterized by an occult drop of cardiac output and a hypoperfusion of vital organs like e.g. the splanchnic region. Due to these pathophysiological characteristics, a therapy would be indicated already in this stadium of shock progression.

The available monitoring tools to detect compensated shock are on the one hand side invasive (intravascular catheter), cost-intensive (cost of the catheter systems), or need extensive training (echocardiography). Consequently, the implementation of advanced haemodynamic monitoring is still low despite the high clinical relevance for the patients.

It is the goal of this project to evaluate in healthy volunteers the routinely implemented technology of photo-plethysmography in its ability to detect haemodynamic changes by extended signal analysis of the pulse-contour and the pulse-wave-transit-times in relation to the gold-standard echocardiography.

Secondary goal of this study is to analyse the physiological and haemodynamic changes during progressive central hypovolaemia displayed by non-invasive or minimal-invasive monitoring devices and associate the changes to each other.

Inclusion Criteria:

• Offered patient information and written informed consent
• Existence of valid health insurance
• Male gender

Exclusion Criteria:

• Patients aged less than 18 years or more than 40 years
• Inability of German language use
• Lacking willingness to save and hand out data within the study
• Evidence of a chronic disease (cardio-vascular, renal, pulmonary, neurological, metabolic, gastro-intestinal)
• Chronic medication
• Signs of a reduced cardiorespiratory capacity
• Signs of an acute illness
• Participation in a prospective intervention trial during the study period
• Anamnestic hints for syncope or disposition to hypotension
• Signs of arterial hypertension
• Signs of inguinal hernia
• Relevant pathologies in the baseline examination of the transthoracic echocardiography
• For the bio-impedance measurements: heart defibrillator

Healthy volunteers