Resting Energy Expenditure and Respiratory Quotient in Adolescents Following Spinal Surgery

Purpose: Determine if Resting Energy Expenditure (REE) and Respiratory Quotient (RQ) change in adolescents undergoing spinal surgery between preop, postop and typical follow-up visits for the purpose of judging nutritional needs post operatively.

Methods: 19 subjects (15 females and 4 males) between the ages of 11 and 19 that underwent spinal fusion surgery participated in the study. Diagnoses included idiopathic scoliosis (13), kyphosis (2), and scoliosis associated with other nonneuromuscular disorders (4). REE and RQ were measured by indirect calorimetry. Subjects were tested supine after a minimum of two hours of fasting. REE and RQ were measured preoperatively (mean 2.6 days before surgery), postoperatively (mean 4.7 days after surgery), and at first clinical follow-up (mean 53 days after surgery). REE was expressed in kcal per day. RQ represented net substrate utilization. An RQ value of 0.70 represents complete fat oxidation and 1.00 represents complete carbohydrate oxidation. A value of approximately 0.80 is normal under resting conditions. The experimental design consisted of one independent variable, timing, with three levels (preop, postop, follow-up) and two dependent variables (REE, RQ). Level of significance set at 0.05.

Results: REE increased significantly from a mean preop value of 1650 kcal/day to a mean postop value of 1810 kcal/day and then returned to a mean 1580 kcal/day at follow-up. RQ significantly decreased from a mean of 0.79 preoperatively to 0.71 postoperatively and then returned to a mean of 0.79 at follow-up.

Conclusion: REE modestly increases about 150 kcal/day following spinal fusion surgery in adolescents. RQ decreases substantially following surgery. Substrate utilization appears to shift to fat oxidation in adolescents following surgery, and thus lipids may be the alimentation of choice, immediately post op. After approximately six weeks, both REE and RQ have returned to preoperative levels, following spinal surgery in adolescents, indicating special nutrition is not required beyond six weeks.