Introduction to Surgical Principles
This chapter reviews several key principles that must be understood when caring for a surgical patient, including metabolism and nutrition, inflammation and injury, and wound healing. This chapter also reviews basic surgical technique and some common comp
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Introduction to Surgical Principles Hamid Abdollahi and Deborah Yu
urgical Metabolism and Nutrition S in the Surgical Patient Once an injury is sustained, the body’s metabolism shifts toward a state with higher metabolic expenditure. Understanding the changes that occur in amino acid, carbohydrate, and lipid metabolism allows the physician and care team to provide optimal nutritional support for the surgical patient [1]. In a healthy adult, approximately 22–25 kcal/kg per day are required to maintain basic metabolic needs. This requirement can increase to up to 40 kcal/kg in patients that have undergone severe stress and injury [1] (Table 2.1). This stress response is triggered by the release of catecholamines and sympathetic activation. Furthermore, during the fasting state, a significant amount of protein is used to provide the substrate for gluconeogenesis in the liver leading to muscle wasting as the body enters a catabolic state [2]. The magnitude of protein catabolism is directly proportional to the severity of the injury with even elective operations and minor injuries leading to decreased protein synthesis and protein breakdown [3]. Nutritional deficits can lead to impairment of the immune system, poor tissue
H. Abdollahi, MD • D. Yu, MD (*) The Plastic Surgery Center, Institute for Advanced Reconstruction, 535 Sycamore Ave, Shrewsbury, NJ 07702, USA e-mail: [email protected]; [email protected]
repair and healing, loss of muscle function, and overall increase in complications. The goal for nutritional support in a surgical patient is to prevent and reverse the catabolic state associated with injury. It is of crucial importance to evaluate each patient’s nutritional status prior to and after any surgical intervention to optimize the success of the treatment. While a detailed physical exam is extremely useful to determine nutritional status, certain lab values are helpful in establishing objective values. These studies include albumin, pre-albumin, and transferrin levels. Concentrations of serum albumin less that 3.0 g/dl are an indicator of malnutrition. Albumin has a half-life of 14–18 days, demonstrating the patient’s recent nutritional status, whereas pre-albumin (half-life 3–5 days) and transferrin (half-life 7 days) may show more rapid changes in nutritional status. These serum markers can guide clinical decisions and serve as a benchmark for nutritional optimization. Furthermore, an individual’s energy requirements can be measured by indirect calorimetry and trends in serum markers as well as estimated from urinary nitrogen excretion [4]. In addition to supplying sufficient calories and protein to prevent the catabolic state and allow for protein synthesis and tissue repair, some patients may require essential vitamin and mineral supplementation. In terms of nutritional supplementation, enteral feeding is preferred over parenteral, not only based on the cost and avoidance of vascular
© Springer International Publishing Switzerland 2017 A.I. Elkwood et al.
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