Spine surgery is usually performed using a posterior approach with the patient in the prone position, but on the other hand this position causes venous engorgement in the back and increases bleeding with the risk of interruption of surgery and increases the need for blood transfusion. The prone position also produces undesirable haemodynamic changes resulting from compression of large vessels and decreased venous return to the heart.~Deep neuromuscular blockade has been shown to improve surgical conditions compared with moderate neuromuscular blockade in various surgical procedures specially different laparoscopic procedures to optimize surgical field conditions. In spine surgery, although many other factors such as the body habitus of the patient and the surgical equipment are important, an improvement in surgical field conditions can be achieved through reducing muscle tension in the back, and also reducing intra-abdominal and thoracic pressure. This goal may be attainable by using deep neuromuscular blockade. Better operating conditions offer the surgeon easier access to the surgical field with less damage. However, the effect of deep neuromuscular blockade on surgical bleeding in spinal surgery in the prone position has been yet under evaluation.~The investigators hypothesise that deep, compared with moderate, neuromuscular blockade would cause less surgical bleeding in spinal surgery in the prone position. The investigators aim to evaluate the effects and superiority of deep neuromuscular blockade on surgical bleeding in patients undergoing posterior lumbar interbody fusion surgery in the prone position.
Reduction of intra-operative blood loss