Bolus versus continuous study

INTERVENTION: The study is a randomised double blind two period crossover study. Two different modes of administration of the usual daily dose divided into 6 intermittent boluses and the second with the same dose administered as a simple continuous flow will be programmed. Each flow pattern is maintained for 2 weeks in a double blind randomized crossover design. Safety and efficacy are evaluated by means of patient‐ and assessor‐based evaluations. To ensure patients? safety during the trial phases of intermittent bolus (IB) and Continuous Infusion (CI), concentration and dosing ranges for all four IMP?s have been carefully considered. The safe maximum daily doses of the drugs Morphine, Baclofen, clonidine and bupivacaine account for both the IB and CI groups. Intermittent Boluses Group (IB) Subjects randomized to receive intermittent boluses will undergo programming by the unblinded investigator of their device in order for the device to deliver the smallest possible dose of continuous background infusion (pump programming does not allow for intermittent boluses alone).The remainder of the total daily dose will be fractionated into 6 intermittent maximum speed (delivered over the shortest time period allowable by the ITDD) boluses delivered at 4 hourly intervals by the pump. The total daily dose delivered by the pump will be the same as the patients? entry daily dose. Continuous Infusion Group (CI) Patients randomized to simple continuous infusion will continue to receive the same dose of drugs at the same rate. Following pump programming patients will be observed in a clinical area for 3 hours with 2 hourly vital signs. Any reported side effects will be noted. Each group will receive intermittent boluses or continuous infusion for a period of 2 weeks. Subjects who have been in group IB will crossover for a 2 week period to group CI and vice versa. CONDITION: Musculoskeletal diseases ; Musculoskeletal Diseases PRIMARY OUTCOME: The Patient Global Impression of Change (PGIC), is a self‐evaluation of the patient?s overall change since the start of the study will be completed at the end of each 2 week period using a 7‐point Likert scale ; Since the last visit to the pain clinic my overall pain control is; We chose the PGIC as a primary outcome measure as it will allow the patient to balance a potential improvement in pain relief with a potential worsening in side effects. SECONDARY OUTCOME: These will be measured at baseline and the end of each 2‐week period.; Visual Analogue Scale of pain relief patients will score their pain on a 10cm line anchored with no pain at the 0cm end and Worst Pain Imaginable at the 10cm end. This will be measured by means of a 5 day pain diary to be completed 5 days before each visit; EQ‐5D is a health related quality of life questionnaire which is divided into 5 dimensions: mobility, self ?care, usual activity, pain/discomfort and anxiety/depression, and will be measured at visit 2, visit 3 and visit 4. INCLUSION CRITERIA: 1. Are implanted with a programmable Intrathecal Therapy Drug Device (ITDD) 2. Have achieved stable pain relief on continuous flow 3. Are capable of giving informed consent 4. Are willing to sign the Informed Consent form 5. Are male or female 6. Aged between 18 years and 65 years of age