MEDICAL APPARATUSES; NAMELY, A HEART FAILURE MANAGEMENT SYSTEM COMPRISING MICROPROCESSOR BASED HARDWARE AND SOFTWARE, A GAS ANALYZER, A PATIENT MOUTHPIECE OR MASK, AND RELATED HOSES AND CABLES; A PORTABLE CARDIOPULMONARY EXERCISE SYSTEM COMPRISING MICROPROCESSOR BASED HARDWARE AND SOFTWARE, A GAS ANALYZER, A PATIENT MOUTHPIECE OR MASK, A CART, AND RELATED HOSES AND CABLES; AND A PULMONARY GAS EXCHANGE MEASUREMENT DEVICE, NAMELY, A GAS ANALYZER