A system for monitoring a progression of heart failure in a patient, the system comprising: a sensor configured to provide one or more signals indicative of respiration of a patient; circuitry coupled to the sensor, the circuitry configured to: determine a plurality of respiration rate and tidal volume measurements during each of a plurality of twenty-four hour periods using the one or more signals indicative of the respiration of the patient; determine a rapid shallow breathing index (RSBI) value for a selected portion of each of a plurality of the twenty-four hour periods based, at least in part, on one or more of the corresponding plurality of the respiration rate and tidal volume measurements; determine a first RSBI aggregate for the RSBI over multiple 24 hours periods based, at least in part, on the RSBI values that fall within a first time window having a first duration of each of the multiple 24 hour periods; determine a second RSBI aggregate for the RSBI over multiple 24 hours periods based, at least in part, on the RSBI values that fall within a second time window having a second duration of each of the multiple 24 hour periods, wherein the first duration is different than the second duration; determine a relationship between the first RSBI aggregate determined for the first time window and the second RSBI aggregate determined for the second time window; and an output coupled to the circuitry for providing an output signal indicative of an HF status of the patient based, at least in part, on a trend of the determined relationship between the first RSBI aggregate determined for the first time window and the second RSBI aggregate determined for the second time window; wherein the RSBI aggregates for the selected portion of each of the plurality of twenty-four hour period are determined, at least in part, by a ratio between the corresponding plurality of respiration rate and tidal volume measurements and wherein the RSBI aggregates for the selected portion of each of the plurality of twenty-four hour period are defined by a minimum or a lower percentile of the plurality of the ratios between the corresponding plurality of respiration rate measurements and the corresponding plurality of tidal volume measurements. a sensor configured to provide one or more signals indicative of respiration of a patient; circuitry coupled to the sensor, the circuitry configured to: determine a plurality of respiration rate and tidal volume measurements during each of a plurality of twenty-four hour periods using the one or more signals indicative of the respiration of the patient; determine a rapid shallow breathing index (RSBI) value for a selected portion of each of a plurality of the twenty-four hour periods based, at least in part, on one or more of the corresponding plurality of the respiration rate and tidal volume measurements; determine a first RSBI aggregate for the RSBI over multiple 24 hours periods based, at least in part, on the RSBI values that fall within a first time window having a first duration of each of the multiple 24 hour periods; determine a second RSBI aggregate for the RSBI over multiple 24 hours periods based, at least in part, on the RSBI values that fall within a second time window having a second duration of each of the multiple 24 hour periods, wherein the first duration is different than the second duration; determine a relationship between the first RSBI aggregate determined for the first time window and the second RSBI aggregate determined for the second time window; and determine a plurality of respiration rate and tidal volume measurements during each of a plurality of twenty-four hour periods using the one or more signals indicative of the respiration of the patient; determine a rapid shallow breathing index (RSBI) value for a selected portion of each of a plurality of the twenty-four hour periods based, at least in part, on one or more of the corresponding plurality of the respiration rate and tidal volume measurements; determine a first RSBI aggregate for the RSBI over multiple 24 hours periods based, at least in part, on the RSBI values that fall within a first time window having a first duration of each of the multiple 24 hour periods; determine a second RSBI aggregate for the RSBI over multiple 24 hours periods based, at least in part, on the RSBI values that fall within a second time window having a second duration of each of the multiple 24 hour periods, wherein the first duration is different than the second duration; determine a relationship between the first RSBI aggregate determined for the first time window and the second RSBI aggregate determined for the second time window; and an output coupled to the circuitry for providing an output signal indicative of an HF status of the patient based, at least in part, on a trend of the determined relationship between the first RSBI aggregate determined for the first time window and the second RSBI aggregate determined for the second time window; wherein the RSBI aggregates for the selected portion of each of the plurality of twenty-four hour period are determined, at least in part, by a ratio between the corresponding plurality of respiration rate and tidal volume measurements and wherein the RSBI aggregates for the selected portion of each of the plurality of twenty-four hour period are defined by a minimum or a lower percentile of the plurality of the ratios between the corresponding plurality of respiration rate measurements and the corresponding plurality of tidal volume measurements.