Role of Preoperative Oral Rehydration Solution on Myocardial Ischaemia During Orthopaedic Surgery under Spinal Anaesthesia: A Prospective Randomised Study.

Objective: Preoperative oral rehydration solution (ORS) supplementation offers wide postoperative benefits, but its role in reducing post-spinal myocardial ischaemia is uncertain. We evaluated this aspect in elective lower limb orthopaedic surgeries and compared it to conventional preoperative fasting.

Methods: Prospectively, we randomised 126 patients aged >60 years into two groups: (A) received reconstituted ORS (1000 mL) during the overnight preoperative fasting, continued up to 2 hrs prior to spinal anaesthesia (SA) induction; (B) kept on conventional overnight preoperative fasting. This study evaluated electrocardiographic ischaemic changes at 2, 5, 10, 15, and 30 minutes after SA induction.

Results: In total, 27 patients (group A: 7; group B: 20) developed transient electrocardiographic ischaemic changes. On intergroup comparison, group B had a significantly higher incidence at all time points, with highest statistical levels at 5- and 10-minutes ((P < 0.001). The receiver operating characteristic curve at a threshold fasting duration (fluids) of >3 hours, had an area-under-curve of 0.74 to predict such changes within 30 minutes of SA induction (sensitivity 96.30%, specificity 55.56%, accuracy 64.29%, odds ratio 32.50, relative risk 20.80, (P < 0.001). Post-spinal hemodynamic changes were higher in group B than in A; hypotension and tachycardia were statistically significant ((P=0.020). The pleth variability index was significantly higher ((P < 0.001), while perfusion index was significantly lower (P < 0.001) in group B at all time points.

Conclusion: Preoperative ORS supplementation significantly reduced post-spinal transient ischaemic electrocardiographic changes in elderly patients than conventional overnight fasting.