Analgesic Requirements for Lumbar Fixation With General Anaesthesia Versus Continuous Caudal Epidural

• The clinical trial will justify the current practice of combined continuous caudal epidural with general anaesthesia in adult patients undergoing lumbar fixation versus general anaesthesia and using this clinical trial to prove the good analgesic effect of continous caudal epidural and its use to decrease opioid use intra and post operative.
• This clinical trial can trace intra and post operative hemodynamic changes while using continuous caudal epidural.
• This clinical trail will record the possible complications and their incidence of continuous caudal epidural.
• Sample size justification: the expected mean intra-operative narcotic consumption among study groups is 186.5 ± 21.6 µg and 106 ± 16.4 µg.

Sample size of 30 patients per group can detect the difference between two groups with power >90% and alpha error 0.05.

• Statistical analysis: this clinical trial will be carried out using the statistical software program. Description of quantitative data as mean and standard deviation and qualitative data as number and percentage.Comparison between the two groups will be done by using the Chi-square test, independent t-test or Mann-Whitney U-test according to the distribution of data. A p-value less than 0.05 will be considered statistically significant.
• Study Procedures:

Patients will be randomly allocated into two equal groups.

Preoperative setting:

• Pre-operative assessment will be done by accurate history taking, full physical examination, laboratory and radiological investigations. including complete blood count (CBC), liver function test (LFT), kidney function test (KFT), prothrombin time (PT) and partial thromboplastin time (PTT) will be checked.
• All patient will be fasting for 8 hours pre operative.
• All patients will be informed about the study design, objectives and techniques.
• Informed consent will be signed by every patient prior to inclusion in the study.
• All patients will be educated about numeric pain scale score which 0 means no pain and 10 means worst imaginable pain.

Intraoperative setting:

• Standard perioperative monitoring will include pulse oximetry, electrocardiogram, end-tidal carbon dioxide measurement, inhaled volatile agent concentration and non-invasive blood pressure measurement.
• Baseline parameters such as oxygen saturation, systolic, diastolic and mean blood pressure, heart rate will be observed.
• Intravenous line will be inserted.
• For all patients, general anaesthesia will be induced by intravenous route using midazolam 0.04 mg/kg, fentanyl 1 µg/kg, propofol 2 mg/kg, atracurium 0.5 mg/kg.
• This will be followed by endotracheal intubation and mechanical ventilation. Maintenance of anaesthesia will be achieved by isoflurane 1.5% in oxygen and air (50:50) and atracurium 0.1 mg/kg every 20 minutes, so as to maintain end tidal carbon dioxide between 35 to 40 mm Hg.
• Intra operative heart rate and mean blood pressure will be recorded. Estimated blood loss will be determined.

Group A: (continuous caudal epidural with general anaesthesia "study group")

• After induction of anaesthesia as mentioned above, patients will be located in the prone position for caudal epidural block. Sterile skin preparation and draping of the entire region will be completed in the standard fashion.
• Fluoroscopy will be utilized and a lateral view will be obtained to demonstrate the anatomic boundaries of the sacral canal. With fluoroscopy, the caudal canal will appear as a translucent layer posterior to the sacral segments. The median sacral crest will be visualized as an opaque line posterior to the caudal canal. The sacral hiatus will be visualized as a translucent opening at the base of the caudal canal. The coccyx will be seen articulating with the inferior surface of the sacrum. A 17- or 18-gauge Tuohy-type needle will be inserted in the midline into the caudal canal. A feeling of a slight "snap" may be appreciated when the advancing needle pierces the sacrococcygeal ligament. Once the needle reaches the ventral wall of the sacral canal, it will be withdrawn and reoriented, directing it more cranially (by depressing the hub and advancing) for further insertion into the canal. The anteroposterior view will be used once the epidural needle is safely situated within the canal and the epidural catheter will be advanced cephalad. In this projection, the intermediate sacral crests will appear as opaque vertical lines on either side of the midline. The sacral foramina will be visualized as translucent and nearly circular areas lateral to the intermediate sacral crests. Once the correct placement of the needle will be confirmed, a catheter will be inserted into the desired location while depth and position will be confirmed fluoroscopically.
• Before the local anaesthetic will be injected, careful aspiration or passive drainage is essential to exclude an unintentional intravascular or intrathecal needle location. An initial dose of 20 ml of 0.25% bupivacaine will be injected in the caudal canal in order to perform sensory block and spare motor power. Then a dose of 10 ml 0.25% bupivacaine will be injected through the epidural catheter every 1-hour intra operatively and at 0-hour and 1-hour post operative. Then the catheter will be removed 1 hour post operative.

Group B: (general anaesthesia "control group")

-General anaesthesia will be induced as described above with administration of extra doses of fentanyl as needed according to hemodynamic changes suggesting pain sensation.

Post-operative setting:

• After completion of surgery, the residual neuromuscular block will be reversed with injection of neostigmine 0.05 mg/kg and atropine 0.01 mg/kg. When patients become suitable for extubation, with stable hemodynamic and adequate muscle power, thorough oral and endotracheal suction followed by extubation will be done.
• Patients will be nursed in post anaesthesia care unit for monitoring of post operative vital signs and for post operative pain assessment by numeric pain scale score at 0-hour and management accordingly.
• Patients postoperative pain will be followed up at the ward at time interval 0, 1, 2, 4, 6 hours.
• Patients will undergo close monitoring for the first 6 hours after caudal injection for overdose or adverse reactions.
• The following factors will be assessed:

1. Intra operative heart rate and blood pressure.
2. Post operative pain assessment according to numeric pain scale score 1-10 as (0= no pain, 10 =worst imaginable pain) and hemodynamic parameters at 0, 1, 2, 4, 6 hours.
3. Time to rescue analgesia (intravenous analgesia administered after surgery) when the numeric pain scale score is 3 or higher. Patients with numeric pain scale score ≥ 3 at any point of time, will receive intravenous morphine 5mg.
4. Estimated blood loss and surgeon satisfaction of surgical field.
5. Total intra operative and post operative analgesia in both groups.
6. Common complications of caudal block in the postoperative period which include hypotension, bradycardia, lower limb numbness and urinary retention. These complications will be recorded and managed accordingly.