Tonometric arterial pulse sensor with noise cancellation.

Arterial tonometry provides for the continuous and noninvasive recording of the arterial pressure waveform. However, tonometers are affected by motion artifact that degrades the signal. An arterial tonometer was constructed using two piezoelectric transducers centered within a solid base.

Measurement and monitoring of electrocardiogram belt tension in premature infants for assessment of respiratory function.

Background: Monitoring of the electrocardiogram (ECG) in premature infants with conventional adhesive-backed electrodes can harm their sensitive skin. Use of an electrode belt prevents skin irritation, but the effect of belt pressure on respiratory function is unknown. A strain gauge sensor is described which measures applied belt tension.

Cardiac force and muscle shortening in regional ischemia: asynchronization and possible uncoupling.

Acute myocardial ischemia affects both cardiac muscle force development and shortening in the affected regions. The exact mechanisms are unclear. We investigated myocardial function during ischemia and reperfusion both experimentally and with a muscle fiber model.

Experimental evaluation of the elastic determinants of myocardial function in vivo.

Shortening of myocardial fibers occurs following force development in those fibers. The extent, speed and timing of shortening are determined by kinetics and extent of force. However, shortening is also influenced by the elastance/viscosity of the muscle tissue, because that determines the coupling between force and shortening.

Effects of partial ischaemia and volume loading on myocardial efficiency and cardiac performance in dogs.

Aims And Methods: To determine whether volume loading may be beneficial for the performance of ischaemic heart, myocardial ischaemia was created by partial occlusion of the left anterior descending coronary artery (LAD) to reduce the blood flow to 30 approximately 40% of basal level in 11 open chest anaesthetised dogs. Global left ventricular function as well as regional performance were studied under four different levels of volume loading, euvolemia (EUVO), hypervolemia (HYPER), normovolemia and hypovolemia.

Results: Left ventricular dP/dt(max) and cardiac output were decreased significantly during partial occlusion (3511.