Effects of postoperative dietary intake on functional recovery of patients undergoing cardiac surgery

Among elderly patients undergoing cardiac surgery, malnutrition is very common and related to muscle wasting known as sarcopenia. Cardiac surgery causes a further decline of nutritional status due to reduced dietary intake (DI); however, the impact of postoperative DI on functional recovery is unclear.

We enrolled 250 consecutive patients undergoing cardiac surgery. Daily DI was measured between postoperative days 3 and 7. Patients were categorized as having sufficient or insufficient DI based on whether their DI met or was less than estimated total energy requirements. Functional capacity was measured using the 6-minute walking distance (6MWD) preoperatively and at discharge. Mean postoperative DI was 22.4 ± 3.0 kcal/kg/day, and postoperative DI was insufficient in 92 patients (36.8%). The prevalence of sarcopenia was not different by postoperative DI. Although there was no significant difference in preoperative 6MWD results (P = 0.65), the sufficient DI group had longer 6MWD at discharge than the insufficient DI group (P = 0.04). In multivariate regression analysis, preoperative poor nutritional status (β = -0.29), duration of surgery (β = -0.18), and postoperative DI (β = 0.40) remained statistically significant predictors for improvement of 6MWD (P < 0.0001, adjusted R² = 0.41).

Postoperative DI was independently associated with functional recovery, but preoperative sarcopenia was not. Regardless of preoperative nutritional status or the presence of sarcopenia, aggressive nutritional intervention in the early stage after surgery helps support functional recovery.