Some patients admitted to intensive care require an extended period of support to overcome their critical illness. These patients consume a disproportionately large amount of hospital resources and recent management strategies have been focused on improving the rehabilitation and outcome for this patient population.
This thesis aimed to understand the clinical application, underlying mechanisms and efficacy of two physiotherapy techniques used in the management of these long-term intensive care stay (LIS) patients: head-up tilt (HUT) using a tilt table, and inspiratory muscle training.
HUT involves placing a patient passively in an upright position in an attempt to improve ventilation and arousal. The passive head-up tilt was demonstrated to be used by the majority of Australian physiotherapists working in intensive care and there was moderate agreement regarding indication and contraindications although lack of evidence of efficacy was highlighted as a reason for non-use of the technique (Study 5.1). This latter point was rectified in the second study which confirmed that HUT produces an increase in short-term ventilation in a group of LIS patients (Study 5.2). The results of the third study suggest that this increase in ventilation is likely to be the result of both improved respiratory system compliance and ventilatory effects of predicted metabolic demand of adopting an upright position (Study 5.3). Notably ventilation was increased without any change in energy expenditure, suggesting that this technique is likely to be safe for patients in whom increased energy demand should be avoided. These study findings support the short-term ventilatory benefits of HUT and its application in the physiotherapy management of the LIS patient.
Rehabilitation of LIS patients continues following their transition from intensive care. Follow-up investigation of LIS patients following ICU discharge demonstrated persistent inspiratory muscle fatigue, despite successful weaning from mechanical ventilation (Study 6.1). Inspiratory muscle training is a commonly used treatment strategy in patients with respiratory muscle weakness of various aetiologies and may be of clinical benefit to rehabilitate poor inspiratory muscle endurance post-weaning. However, the training effect of loaded breathing is not known and may be influenced by changes in inspiratory muscle recruitment and resultant breathing pattern. To address this issue the fifth study investigated chest wall motion in patients with chronic airways disease (who make up a large proportion of patients who have delayed weaning from ventilation) (Study 6.2). The final study involved a series of case reports of the effects of inspiratory muscle training in LIS patients post ICU discharge (Study 6.3). These studies suggest inspiratory muscle dysfunction may be present in LIS patients and require specific rehabilitation in the form of inspiratory muscle training following transition from intensive care.
These studies add to the knowledge base for physiotherapy rehabilitation of LIS patients by understanding current practice, providing an evidence base for the efficacy of interventions and also improving the understanding of underlying mechanisms to adapt physiotherapy treatment. In addition, this thesis has identified further potential research directions to improve the management of this complex clinical population