A cardiac rhythm management system detects hypotension, such as by using thoracic impedance to detect a fluid shift away from the thorax. An elongated conduit with a V-shaped groove extends integrally along the outer wall of the riser grip. The audio signal processing apparatus is capable of appropriately adjusting the magnitude of an acoustic signal output from a headphone, according to the product specifications of the headphone. The process provides for the preparation of a final graft polyol having a solids level of from 30 to 70% in a continuous process. The gripping assembly includes threaded tubes surrounding a rod with opposite threads at each end for driving the tubes, whereby the gripping fingers on the gripping assembly are movable to grip the vault buss blocks.