Comparison of the effect of different doses of phenylephrine infusion on the prevention of hypotension in the elderly under spinal anaesthesia in orthopaedic surgery.

Background: Considering the vasopressor drug categories and doses that can be used for elderly patients following hypotension are few, the present trial aimed to compare the effect of different doses of phenylephrine infusion on the prevention of hypotension in elderly patients undergoing orthopaedic lower extremities surgery.

Methods: This randomised, double-blind prospective clinical trial was conducted by including 60 elderly patients older than 60 years and classified as American Society of Anesthesiology class I and II who were candidates for femur fracture fixation surgery. White and black cards randomly allocated patients to: group A (25µg/kg/h phenylephrine) or group B (35µg/kg/h phenylephrine).

Results: At the T-T time points, group A's systolic and diastolic blood pressure was significantly higher than in group B's (p < 0.05). However, after 27 minutes (T-T) of phenylephrine infusion, statistical analysis showed no significant difference between the two groups regarding blood pressure (T-T). The frequency of bradycardia and reactive hypertension in group B were significantly higher than in group A (p = 0.02) and (p = 0.03), respectively. There was no significant difference between the bleeding loss, blood transfusion and crystalloid volume in both groups (p > 0.05).

Conclusion: Our trial illustrated that high-dose phenylephrine infusion could not assure haemodynamic stability and may cause some side effects.