Oxidative stress is associated with muscle wasting after aortic surgery

Abstract

ICU Acquired Paresis (ICUAP) leads to prolonged recovery and reduced quality of life in survivors of ICU. Patients undergoing aortic surgery experience an ischaemia-reperfusion (IR) injury mimicking the SIRS/sepsis response. 50% of patients demonstrate muscle loss post-operatively, representing a homogenous cohort to study the pathogenesis of ICUAP.

Objectives:

1. To investigate if oxidative stress in these patients correlated with loss of muscle bulk in the post-operative period

2. To assess a new system for measuring oxidative stress (RedoxSys^TM) that measures static (sORP) and capacity (cORP) oxidation-reduction potential and compare it to conventional markers

Methods: 11 Patients undergoing major aortic surgery were grouped post-hoc into either wasters (n=6) or non-wasters (n=5) based on serial rectus femoris ultrasound measurements (≤ or ≥ 10% muscle bulk loss). Serum samples (day 0,1,3 & 7) post-operatively were tested for sORP, cORP and a marker of ischaemia (xanthine) by HPLC.

Results: 24-hours following surgery, sORP increased (17.2% vs 4.3%, p =0.03) and cORP decreased (46.7% vs 29.6%, p = 0.004) significantly more in wasters compared to non-wasters. Both returned to baseline by the 7^th post-operative day in non-wasters but cORP remained persistently reduced in wasters (32.9% vs 12.0%, p=0.04). Serum xanthine was persistently raised in wasters compared to non-wasters across all time points.

Conclusion: Oxidative stress following aortic surgery was persistently raised in patients with muscle wasting compared to those without. The RedoxSYS system agreed with another surrogate of oxidative stress. Further investigation of its utility in monitoring the degree of oxidative stress is warranted.