The aim of this clinical trial is to compare the time to first analgesic request between dexmedetomidine and fentanyl as adjuvants in erector spinae plane block in patients undergoing simple nephrectomy .
• Secondary outcome Pain scores; Numerical Rating Scale (NRS) at rest and when coughing \[at 1, 2, 4, 8, 16 and 24 hours postoperatively.\] The total opiod dose in the first 24 hours postoperatively. Duration of analgesia is defined as duration between block administration and time of first analgesic request.
Any adverse effects related to anesthesia or the technique. Incidence of Postoperative nausea \& vomiting . Block related complication during and after block procedure till 24hours postoperatively (local anesthetic systemic toxicity, pneumothorax and vascular puncture during block procedure).
Intraoperative haemodynamics parameters MAP ,HR , co2 and SP O2 . Postoperative haemodynamics parameters MAP , HR and SP O2 \[at 1, 2, 4, 8, 16 and 24 hours postoperatively. \]
Age >18 years old Both sex patients who are American society of Anesthesiologists class I or
Patient's refusal.
body mass index (BMI) ≥40 kg/m2.
Local infection at site of block.
Spine deformities