Intraaortic balloon counterpulsation (IABP) is the most widely used mechanical support in the assistance of a failing heart.1 Despite extensive research in this field no experimental or clinical studies have been undertaken to evaluate the most effective manner to wean IABP.2 The research reported in this thesis examines early recognition of cardiac decompensation and the management of IABP weaning. Conducted in three phases, the aim of this research programme was to determine the best manner by which to wean IABP. Phase 1 utilised a comparative descriptive design to examine IABP practice at a single cardiothoracic tertiary referral hospital. The majority of data collection was prospective, however, the required sample size saw inclusion of some retrospective data. This single centre data were than compared with an international registry to contrast IABP management and outcome. Phase 2 utilised a questionnaire survey to audit all Australasian intensive care units. Survey results were combined and statistically analysed to describe Australasian IABP management, weaning and outcome. Phase 3 utilised a quasi-experimental, one-group, posttest-only design to clinically validate a tool designed to monitor a patient's cardiac function - the 'cardiac decompensation tool'. Phase 1 saw data collected for 669 IABP insertions over an 11 year period at a single Australian hospital. This cohort was compared against the 38,606 patient dataset of The Benchmark Counterpulsation Outcomes Registry. Australian IABP practice saw later application of the device in a higher acuity patient. Australian practice demonstrated a prejudice toward intraoperative use (34.2% versus 16.6%; p=< 0.0001) and an aversion to catheter laboratory support (10.6% versus 19%; p=< 0.0001). Australian mortality while slightly higher, remained comparable (22% versus 20.8%; p=ns). Phase 2 response rate was 60%. The most common Australasian method of IABP support withdrawal was ratio reduction only (61%). Units with a documented weaning policy were less likely to require balloon reinsertion or pharmacologic escalation following IABP removal (p=0.06). Indicators most likely to demonstrate a patient's readiness for IABP weaning were blood pressure (92%), heart rate (76%) and wedge pressure (59%). Phase 3 revealed cardiac decompensation tool scores to increase immediately prior to a treatment escalation (p=0.022) and decrease immediately following this escalation in therapy (p=0.0096). There was also some indication of decreasing scores prior to treatment minimisation (p=0.005). Tool scores demonstrated a corresponding treatment fluctuation up to three hours prior to the treatment intervention. With Phase 1 and 2 revealing many aspects of IABP practice to vary, the need for some direction regarding weaning is evident. Timely recognition of cardiac decompensation during IABP weaning allows an opportunity for the earlier escalation of treatment and consequent provision of increased cardiac support. Application of the Phase 3 cardiac decompensation tool can only assist in ensuring the best manner by which to support IABP weaning.