🔥⚡️LM11 Lecture

Physiological stressors

Lead to a hypermetabolic state with muscle wasting

Why does the body release energy during physiological stress?

To improve chances of survival

Hormones of stress that maintain blood volume

Aldosterone and antidiuretic hormone (ADH)

Aldosterone

Increases Na reabsorption

Antidiuretic hormone (ADH)

Increases water reabsorption

Epinephrine is released from the

Adrenal medulla

Effect of epinephrine on metabolic rate

Increases metabolic rate by increased glycolysis

Effect of epinephrine on liver glucose release

Increases release of glucose from liver by glycogenolysis and gluconeogenesis

Effect of epinephrine on adipocytes

Increases release of fatty acids and glycerol from adipocyte by lipolysis

Effect of stress on pancreatic hormones

Increases glucagon and decreases insulin

Effect of glucagon/insulin changes on the liver

Increases liver glycogenolysis and gluconeogenesis

Effect of glucagon/insulin changes on adipocytes

Increases adipocyte lipolysis

Acute effects of cortisol release

Survival

Acute cortisol effect on muscle amino acids

Increases release of amino acids from muscle by increased protein degradation and decreased synthesis

Acute cortisol effect on adipocytes

Increases release of fatty acids and glycerol from adipocyte by lipolysis

Acute cortisol effect on liver glucose release

Increases release of glucose from liver by glycogenolysis and gluconeogenesis

Acute cortisol effect on insulin response

Decreases adipocyte and muscle response to insulin

What does cortisol-induced insulin resistance do to tissue glucose absorption?

Decreases tissue glucose absorption

What happens to blood glucose with acute cortisol release?

Blood glucose increases

Chronic effects of cortisol are

Detrimental to healing and recovery

Chronic cortisol effect on protein synthesis

Decreases protein synthesis

Tissues impacted by decreased protein synthesis during chronic cortisol exposure

Muscle, bone, connective tissue, and skin

Results of chronic cortisol on tissues

Muscle wasting, osteoporosis, impaired wound healing, and thin skin

Can increased protein ingestion reverse cortisol-related loss?

No, it can only reduce the rate of protein loss while cortisol is present

Effect of chronic cortisol on bone calcium

Decreases Ca in bone

Why does bone calcium decrease with chronic cortisol?

Increased osteoclast activity increases Ca release from bone

Effect of chronic cortisol on glucose control

Increases insulin resistance and release of glucose, causing hyperglycemia

Effect of chronic cortisol on immune function

Decreases immune function and increases infections

Purpose of the local inflammatory response

Contain and destroy infectious agents to prevent further tissue damage and promote healing

What begins the local inflammatory response?

Release of histamine from mast cells by complement protein

Effect of histamine at the injury site

Dilates arterioles at the site of injury

Why are arterioles dilated during local inflammation?

To increase blood flow and bring more leukocytes

Capillary change during local inflammation

Increased capillary protein permeability

What does increased capillary permeability help cause?

Edema and increased interstitial colloid osmotic pressure

How are immune cells attracted during local inflammation?

Endothelial cell expression of adhesion molecules

Diapedesis

Immune cells leave the vessel and become phagocytes

What do phagocytes do?

Engulf microorganisms and destroy them with reactive oxygen species

Oxidative burst

Destruction of microorganisms with reactive oxygen species

Cytokines

Communication among immune cells

Eicosanoids

Derived from fatty acids

Omega-3 effects on inflammation

Anti-inflammatory

Omega-6 and saturated fat effects on inflammation

Pro-inflammatory

How do anti-inflammatory drugs reduce eicosanoids?

By inhibiting cyclooxygenase

Systemic inflammatory response

Is stimulated by local cytokines released at a high enough level

Acute phase response

Causes the liver to release acute phase proteins

C reactive peptide function

Targets pathogen for destruction

Lysozymes function

Destroy pathogen

Hepcidin effect

Decreases circulating Fe

What happens to blood albumin in systemic inflammatory response?

It decreases

Why does blood zinc decrease during systemic inflammatory response?

Because albumin transports zinc and liver synthesis decreases

Why are more amino acids released during systemic inflammatory response?

For gluconeogenesis, tissue repair, and immune response

Negative nitrogen balance

Means muscle wasting

Effect of fever on metabolism

Increases metabolism

SIRS

Systemic inflammatory response syndrome

Signs of SIRS

Substantial increase in heart rate and respiratory rate and abnormal white cell count

Immediate concern for those under acute stress

Remove the stressor

Major early issue in acute stress

Fluid loss and electrolyte imbalance affecting blood pressure maintenance

If IV fluids are required in acute stress, what should be included?

Dextrose

What should be done once the patient is stable under acute stress?

Determine nutritional needs and provide nutrition therapy

Why does acute stress create a hypermetabolic state?

Due to hormone release

Why does acute stress increase risk of muscle wasting?

Negative nitrogen balance

Why does acute stress increase infection and refeeding syndrome risk?

Because insulin resistance causes hyperglycemia

Goals of nutrition therapy in acute stress

Preserve lean body mass, maintain immune function, and promote healing

Why is body weight tricky when determining energy needs in acute stress?

Fluid imbalance impacts body weight used to determine metabolic rate

How should energy needs be determined in acute stress?

Determine resting metabolic rate to ensure adequate calories

Critically ill energy needs

25-30 kcal/kg/day

Energy needs for obese critically ill patients

22-25 kcal/kg ideal body weight/day

Normal protein requirement

0.8 g/kg body weight/day

Protein requirement in acute stress

2x normal

Protein requirement in obese patients under acute stress

3x normal ideal body weight

Why is nitrogen balance difficult to achieve during a stressor?

Because of cortisol and inactivity

Carbohydrate recommendation in acute stress

50-60% of caloric intake

When hyperglycemia is present in acute stress, what macronutrient change may be used?

Increase fat up to 50% of calories

When should fat be restricted in acute stress?

If blood triglycerides are greater than 500 mg/dl

Micronutrient issue in acute stress

Monitor electrolytes

Antioxidants studied in acute stress

Vitamin C, vitamin E, selenium, and zinc

Benefit of early enteral feeding in acute stress

Fewer complications and shorter hospital stay

When should early enteral feeding begin in acute stress?

Within 24-48 hours

What should happen to nutrient prescriptions as the patient recovers from acute stress?

Reassess nutrients often

Types of burn injuries

Fire, chemical, radiation, and electricity

Most frequent complications of burns

Infection and hypovolemia

Why do burn injuries require fluid and electrolyte replacement?

Due to fluid loss

Effect of burns on metabolic rate

Increases metabolic rate 2-3 fold depending on extent and depth of burn

How long can metabolic rate remain elevated after burn injury?

Up to 1 year after injury

Why is body temperature increased after burns?

More energy is needed for thermoregulation

Why is water loss increased in burns?

Thermoregulation and increased blood flow to the open wound cause fluid to evaporate

If burn energy needs are not addressed, what can happen?

Muscle and bone loss, gluconeogenesis, insulin resistance, and reduced child growth

Goals of burn nutrition therapy

Achieve nitrogen balance, minimize tissue loss, and maintain body weight

How is resting metabolic rate determined in burns?

Indirect calorimetry or predictive equation with stress factor 1.3

Best overall diet approach in burns

High calorie, high protein while avoiding hyperglycemia

Risk of hyperglycemia in burn patients

Fatty liver and infections

Protein oxidation in burns

Is 50% higher than resting

Adult protein needs in burns

2x normal

Child protein needs in burns

4x normal

Micronutrients emphasized in burns

Vitamin A, vitamin C, and zinc

How should hydration be monitored in burn patients?

By urine output and serum electrolytes

When should early enteral feeding begin in burns?

Within 4-6 hours

Benefit of early enteral feeding in burns

Reduces catabolism and weight loss

If oral feeding is possible in burns, what is recommended?

Many small meals and nutrient-dense supplements

If severe burns decrease motility, what feeding route may be needed?

Nasointestinal feeding