Nutrition and Wound healing

Question 1

What happens in starvation?

Answer 1

In starvation:

1. The metabolic rate decreases within 24 hours after onset of starvation
2. Gluconeogenesis will use amino acids as its primary substrate; these AA come from protein intake
3. Once this occurs, fatty acids are immobilized from fat stores to preserve overall muscle mass.
4. The brain, which normally uses glucose, can use products from fatty acid metabolism known as ketone bodies.
5. The starvation process ensures human preservation by maintaining lean body mass and overall muscle protein.
6. This causes a decrease in overall amino acid demand due to starvation and decreasing overall protein turnover, thus preserving lean body mass

Question 2

What happens in stress response

Answer 2

During stress:

1. Decreased systemic vascular resistance leads to low blood pressure which increases cardiac output, increases metabolic demands on the heart.
2. Muscle is sacrificed to power the body, which leads to significant loss of lean body mass; this deters wound healing and increases the risk of pressure ulcer formation.

Question 3

What is Protein calorie or protein energy malnutrition (PEM)?

Answer 3

PEM develops slowly. Many people develop PEM due to metabolic starvation. PEM is characterized by a depletion of muscle visceral protein stores, and overall body fat. Even mild protein energy malnutrition affects wound healing.

Question 4

How does PEM lead poor wound healing?

Answer 4

Three folds:

1. Loss of lean body mass
2. Impairment of collagen and protein synthesis
3. The overall impairment of the immune system.

Question 5

Forms of protein energy malnutrition

Answer 5

Three forms:

1. Marasmus: wasting with overall severe calorie deprivation or severe impaired absorption of calories, often with concomitant vitamin and mineral deficiencies. Usually have normal visceral protein levels but have significant weight loss.
2. Kwashiorkor: hypoalbuminemia which is normal to excessive calorie input with inadequate protein input. There is increased edema due to decreased oncotic pressure in the vascular system. This causes decreased cellular immunity. Infection, skin breakdown and pressure ulcers are common in these patients.
3. Maramus kwashiorkor: usually a late stage finding in severe to profound malnutrition. This has a highest associated morbidity and mortality.

Question 6

Vitamin C deficiency

Answer 6

Deficiency causes “scurvy”
Vitamin C improves leukocyte margination and migration. Therefore, vitamin C deficiency interferes with the inflammatory response in wound healing, and worsens the resistance to infection.
Vitamin C also drives collagen synthesis so a deficiency in vitamin C causes impaired collagen synthesis and cross inking and maturation of collagen.

Question 7

Vitamin A deficiency

Answer 7

Vitamin A deficiency affects wound healing at all stages by impacting function of macrophages, monocytes, fibronectin deposition and overall cellular adhesion. The overall effect is a decreased in structural strength of the wound.
Vitamin A tends to counteract the effect of steroids; therefore must be cautious when giving vitamin A to patients who are taking steroids. Vitamin a causes an increase in the inflammatory response due to enhanced lysosoction, decrease infaflammatory al membrane permeability.

Question 8

Vitamin D deficiency

Answer 8

Vitamin D is formed by sunlight. Deficiency of this vitamin in children causes Ricketts and in adults causes osteomalacia. Vitamin D enhances active calcium transport.
A toxicity causes an elevated level of calcium and phosphorus, leading to calcifications in the soft tissue.

Question 9

Vitamin E deficiency

Answer 9

Vitamin E is an anti-oxidant with excellent anti-inflammatory properties. it is a fat soluble vitamin.
Given in excess can decrease collagen prodution, a decrease in inflammatory response and can affect overall l wound healing.

Question 10

Glutamine deficiency

Answer 10

Glutamine is the most abundant amino acid in the body. It is a primary fuel source for lymphocyte and is essential for lymphocyte proliferation.

Question 11

Arginine deficiency

Answer 11

Arginine deficiency causes decrease in wound-breaking strength, decreased collagen deposition.

Question 12

Zinc deficiency

Answer 12

Zinc is important in the processes of epithelialization, phagocytosis, fibroblast proliferation and bactericidal activities of WBCs.  Zinc deficiency occurs in:
1.  Chronic alcoholism
2. Severe surgical trauma
3. Psoriasis
4. GI fistulas
5.  large body surface area burns
Daily requirement:  220 mg
Excess zinc administration can lead to problems with septic patients and should be limited to just a few days at a time.

Question 13

Iron deficiency

Answer 13

Iron is important in the oxygen carrying capability of hemoglobin and in DNA production. It is also important in collagen maturation. Deficiency leads to anemia

Question 14

What is significant weight loss?

Answer 14

2% loss in 1 wk or 10% loss in 6 months is significant weight loss.

Question 15

Total lymphocyte count

Answer 15

Total lymphocyte count: 2000 / ml - normal
Mild malnutrition: 1500 - 1800
Moderate malnutrition: 900 - 1500
Severe malnutrition: < 900

Question 16

Albumin

Answer 16

Normal 3.5 - 5 g/ dL
Mild deficiency: 2.4 - 2.8 g/dL
Moderate deficiency: 2.1 - 2.4 g/dL
Severe deficiency: < 2.1 g/dL

Question 17

Prealbumin

Answer 17

Short half-life 48-72 hrs
Not affected by dehydration or overall hydration status
Not affected by renal failure
Not an acute phase reactant that increases in times of stress

Question 18

Nutritional requirements for wound healings

Answer 18

For healthy individuals:
Calories:  1200 - 2000 Kcal/d
Protein 0.8 g/kg/d lean body mass (10% of calories)
Fluids:  3000 ml/day
Carbohydrate:  60% of calories
Fat: 30% of calories
Vitamin supplementation

For patients with significant wounds and under stress
Calories:  30 Kcal/kg/day
Protein:  1.5 - 2 g/kg/d
Fluids:  1 ml/dal
Carbohydrates:  50-60% of calories
Fat - 25% of calories
Vitamin supplementation