The Effect of Intra-operative Intravenous Vitamin C Supplementation on post-operative pain in patients undergoing Reconstructive Head and Neck Flap Surgeries: A Randomized Controlled Trial.

Pain is defined by the International Association for the Study of Pain (IASP) as An unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage. It is a complex phenomenon that includes both sensory-discriminative and motivational-affective components. The sensory discriminative component of pain depends on ascending projections of tracts (Spinothalamic tracts) to the cerebral cortex. The motivational affective responses to painful stimuli include attention and arousal, somatic and autonomic reflexes, endocrine responses and emotional changes.

Postoperative pain is present in up to 80 percentage of patients undergoing surgery, and is of significant concern. It impairs the quality of life (such as sleep quality and level of activity) and impacts patient recovery, opioid consumption, and overall hospital stay and contributes to chronic postoperative pain.

The commonly used postoperative analgesic agents include opioids and nonsteroid anti inflammatory drugs (NSAIDs) are associated with untoward side effects including respiratory depression and other complications such as nausea or vomiting. In addition, NSAIDs, which are usual adjuvants to opioid-based regimens, are known to contribute to adverse gastrointestinal, renal side-effects and bleeding.

The goal of this study is to evaluate the effectiveness of intravenous Vitamin C in reducing pain. Vitamin C, the L enantiomer of ascorbate also known as ascorbic acid, is a water-soluble antioxidant ubiquitously present in a variety of fruits and vegetables. The importance of vitamin C in wound healing and hemostasis was first realized more than 260 years ago when it was found to be a cure for scurvy, a disease characterized by spontaneous bleeding, anemia, and gum ulceration. Besides its role in hemostasis, vitamin C is also known to exhibit analgesic functions. Recent evidence has attributed the antinociceptive action of Vitamin C to its antioxidant, neuroprotective, and neuro-modulatory properties. Vitamin C has been shown to reduce acute pain and the prevalence of complex regional pain syndromes (CRPS) with its antinociceptive effect. Considering that intravenous vitamin C can trigger oxidative hemolysis with glucose 6 phosphate dehydrogenase (G6PD) deficiency, we will be screening the patients for G6PD activity prior to their inclusion in the study.