Here is the design of a clinical trial:

Official Title: A Prospective Randomized Double Blind Trial of the Efficacy of a Bilateral Lumbar Erector Spinae Block on the 24h Morphine Consumption After Posterior Lumbar Interbody Fusion Surgery.

Included conditions:
- Pain, Postoperative
- Anaesthesia
- Surgery
- Nerve Block
- Anesthesia, Local
- Back Pain
- Spinal Fusion

Study Armgroups:
- {'label': 'ESB group', 'type': 'ACTIVE_COMPARATOR', 'description': 'Erector Spinae plane block with 20 ml levobupivacaine 0,25% on each side. General anesthesia with 15 mcg sufentanil, 2-3 mg/kg propofol and 0,5 mg/kg Rocuronium Bromide during spine fusion surgery (1 or two intervertebral levels). Maintainance of general anesthesia with sevoflurane.\n\nPostoperative analgesia with Ketorolac (0,5 mg/kg), paracetamol 1000 mg (4 times/ day) and Morphine PCA. Dexamethasone is administered for the prevention of nausea.', 'interventionNames': ['Procedure: Erector spinae plane block', 'Drug: Levobupivacaine 0,25%', 'Procedure: spine fusion', 'Drug: Sufentanil', 'Drug: propofol', 'Drug: Rocuronium Bromide', 'Drug: sevoflurane', 'Drug: paracetamol', 'Drug: Ketorolac', 'Drug: morphine pca', 'Drug: Dexamethasone', 'Drug: Morphine']}
- {'label': 'SHAM group', 'type': 'SHAM_COMPARATOR', 'description': 'Erector Spinae plane block with 20 ml NaCl 0,9% on each side General anesthesia with 15 mcg sufentanil, 2-3 mg/kg propofol and 0,5 mg/kg Rocuronium Bromide during spine fusion surgery (1 or two intervertebral levels). Maintainance of general anesthesia with sevoflurane.Postoperative analgesia with Ketorolac (0,5 mg/kg, paracetamol 1000 mg 4times/ day and Morphne PCA .Dexamethasone is administered for the prevention of nausea.', 'interventionNames': ['Procedure: Erector spinae plane block', 'Procedure: spine fusion', 'Drug: NaCL 0,9%', 'Drug: Sufentanil', 'Drug: propofol', 'Drug: Rocuronium Bromide', 'Drug: sevoflurane', 'Drug: paracetamol', 'Drug: Ketorolac', 'Drug: morphine pca', 'Drug: Dexamethasone', 'Drug: Morphine']}

Interventions:
- {'type': 'PROCEDURE', 'name': 'Erector spinae plane block', 'description': 'Ultrasound guided deposition infiltration between a lumbar transverse proces and the erector spine muscle', 'armGroupLabels': ['ESB group', 'SHAM group'], 'otherNames': ['Locoregional anaesthesia']}
- {'type': 'DRUG', 'name': 'Levobupivacaine 0,25%', 'description': '20 ml levobupivacaine 0,25% used for the infiltration between the transverse process and the erector spinal muscle', 'armGroupLabels': ['ESB group'], 'otherNames': ['chirocaine']}
- {'type': 'PROCEDURE', 'name': 'spine fusion', 'description': 'fusion of lumbar vertebral body on 1 or two levels', 'armGroupLabels': ['ESB group', 'SHAM group']}
- {'type': 'DRUG', 'name': 'NaCL 0,9%', 'description': '20 ml solution used for the infiltration between the transverse process and th erector spinal muscle', 'armGroupLabels': ['SHAM group']}
- {'type': 'DRUG', 'name': 'Sufentanil', 'description': 'opioid used for the preoperative analgesia for back surgery during general anaesthesia ( 15 mag)', 'armGroupLabels': ['ESB group', 'SHAM group'], 'otherNames': ['sufenta']}
- {'type': 'DRUG', 'name': 'propofol', 'description': 'induction agent for general anaesthesia ( 2-3 mg/kg)', 'armGroupLabels': ['ESB group', 'SHAM group']}
- {'type': 'DRUG', 'name': 'Rocuronium Bromide', 'description': 'muscle relaxant used during general anaesthesia ( 0,5 mg/kg)', 'armGroupLabels': ['ESB group', 'SHAM group'], 'otherNames': ['sermon']}
- {'type': 'DRUG', 'name': 'sevoflurane', 'description': 'inhalation aesthetic used for the maintenance of general anaesthesia', 'armGroupLabels': ['ESB group', 'SHAM group']}
- {'type': 'DRUG', 'name': 'paracetamol', 'description': 'postoperative drug for analgesia ( 1 gram 4/day)', 'armGroupLabels': ['ESB group', 'SHAM group']}
- {'type': 'DRUG', 'name': 'Ketorolac', 'description': 'non steroidal into inflammation drug used for postoperative analgesia (0,5 mg/kg)', 'armGroupLabels': ['ESB group', 'SHAM group']}
- {'type': 'DRUG', 'name': 'morphine pca', 'description': 'postoperative morphine pomp, controlled by the patient. ( bolus 1 mg, lockout 8 minutes) the solution contains morphine 1 mg/ml + dehydrobenzperidol 0,05 mg/ml', 'armGroupLabels': ['ESB group', 'SHAM group'], 'otherNames': ['patient controlled analgesia']}
- {'type': 'DRUG', 'name': 'Dexamethasone', 'description': 'drug given during general anaesthesia to prevent postoperative nausea', 'armGroupLabels': ['ESB group', 'SHAM group'], 'otherNames': ['aacidexam']}
- {'type': 'DRUG', 'name': 'Morphine', 'description': 'loading dose morhine 0,1 mg/kg at the end of surgery', 'armGroupLabels': ['ESB group', 'SHAM group']}

Primary Outcomes:
- {'measure': '24 hour morphine consumption', 'description': 'total milligrams (0-150) of morphine used in the first 24 hours after surgery, extracted out of the pca pump data.', 'timeFrame': '24 hours'}

Please estimate the sample size based on the assumption: 
Mean morphine consumption of 51 mg with a standard deviation of 19 mg, type 1 failure risk (significance level) of 5%, type 2 failure risk (power) of 20%, and the use of an independent samples t test.
Sample size
        Our sample size calculation is based on data from a randomized controlled trial comparing the effect of systemic infused lidocaine with placebo on the 24-h morphine requirement in posterior lumbar arthrodesis [11]. We considered a 25% reduction in PCA morphine consumption to be clinically relevant. To calculate the sample size, we assumed a mean of 51-mg morphine with standard deviation of 19âmg (mean morphine consumption for the placebo group of the above-mentioned trial), a type 1 failure risk of 5%, and a type 2 failure risk of 20%. Thirty-five patients are required in each group to detect a 25% reduction in morphine equivalent over 24âh. The sample size calculation was based on an independent samples t test. We plan to include 80 patients in total to compensate for potential dropouts and uncertainty in predicting the actual standard deviation.