Patent ID: 8690804

Claim:
A CPR apparatus comprising a chest compression unit, a mounting device for mounting the chest compression unit on a patient, the chest compression unit comprising a housing, a plunger disposed in the housing, a compression member at one end of the plunger and extending from the housing, a reversible electromotor, a mechanical device connected from the motor to the plunger for driving the plunger in a reciprocating manner with respect to the housing and for translating rotational motion of the motor to linear motion of the plunger, an electromotor control unit connected to the motor and including a microprocessor, a first monitor operable for monitoring the position of the plunger in respect of the housing, a second monitor operable for monitoring the position of the plunger in respect of the mechanical device for translating rotational motion to linear motion, the positions monitored by the first and second monitors being communicated to the electromotor control unit, wherein the mechanical device for translating rotational motion to linear motion comprises a ball screw nut mounted on a ball screw shaft driven by the electromotor, wherein the housing comprises a distal end wall through which the ball screw shaft extends, wherein the ball screw shaft portion extending from the housing comprises a pulley, and wherein the pulley is a first toothed belt pulley and a driving shaft of the electromotor comprises a second toothed belt pulley such that rotation of the second toothed belt pulley is transferred to the first toothed belt pulley by a toothed belt.