Nutritional Support in Trauma Flashcards
What is the medical definition of trauma?
an injury or wound to living tissue caused by an extrinsic agent
What are examples of trauma?
- road traffic accident
- stabbing
- gunshot wound
- burns
- aneurysm repair
- tumour excision
- caesarean section
- amputation of diabetic foot
What are the immediate and later features of physical trauma?
immediate:
- intravascular fluid loss
- extravascular volume
- tissue destruction
- obstructed / impaired breathing
later:
- as above as well as:
- starvation
- infection
- inflammation
all of these factors have potential mortality
How might someone in a RTA be treated?
What may they die from if they do not recover?
if they cannot eat or drink, they are given IV fluids (3L 5% dextrose / day)
they may then rapidly lose weight
the death certificate cites “pneumonia” as the cause of death
What are the stages involved in someone dying from pneumonia after a RTA where they cannot eat or drink?
blood loss + impaired breathing + infection barrier penetration
- decreased circulating volume
- decreased red cells + O2
- decreased white cells + immune response
- decreased cardiac output / blood pressure
- decreased organ perfusion
- decreased energy substrate delivery to cells and tissues
this leads to major organ dysfunction (GI / heart / brain / renal) and infection barrier penetration (sepsis)
What do the following lines represent for causes of mortality after major trauma?
red = haematological shock
pink = head injury
green = acute respiratory distress syndrome
blue = multi-organ failure
What can cause shock?
interruption to the supply of substrates to the cell:
- oxygen, glucose, water, lipids, amino acids, micronutrients
interruption to the removal of metabolites from the cell:
- CO2, water, free radicals, toxic metabolites
What are the 3 stages involved in mortality from trauma?
phase 1 - clinical shock
someone may make a spontaneous recovery - physiological adaptation
or an intervention may be needed - resuscitation
phase 2 - hypercatabolic state
phase 3 - recovery (anabolic state)
When does shock (phase 1) tend to develop?
What is secreted?
- develops within 2-6 hours after injury
- lasts from 24-48 hours
- cytokines, cortisol and catecholamines are secreted
What happens to the body during phase 1 (shock)?
What are the primary aims in this phase?
- increased heart rate (tachycardia)
- increased respiratory rate
- peripheral vasoconstriction
- selective peripheral shut-down to preserve vital organs
- hypovolaemia
primary aims:
- stop bleeding
- prevent infection
When does phase 2 (catabolic state) develop?
What is secreted during this stage?
- develops around 2 days after injury
- it is necessary for survival but if it persists/is severe it increases mortality
- secretion of catecholamines, glucagon and ACTH leading to cortisol production
What are the effects on the body of phase 2 (catabolic state)?
What are the primary aims in this phase?
- increased oxygen consumption
- increased metabolic rate
- increased negative nitrogen balance
- increased glycolysis
- increased lipolysis
primary aims:
- avoid sepsis
- provide adequate nutrition
When does phase 3 (anabolic state) occur?
What does it coincide with?
occurs around 3-8 days after uncomplicated surgery
may not occur for several weeks after severe trauma and sepsis
coincides with beginning of diuresis and request for oral intake
What happens to the body during phase 3 (anabolic state)
What is most critical during this phase?
gradual restoration of:
- body protein synthesis
- normal nitrogen balance
- fat stores
- muscle strength
- adequate nutrition supply is critical in this phase
- risk of refeeding syndrome
- may last a few weeks / few months
- obesity paradox
What are the 6 stages involved in the inflammatory response at a trauma site?
- bacteria and pathogens enter the wound
- platelets release clotting factors
- mast cells secrete factors that mediate vasodilation to increase blood delivery to the injured area
- neutrophils & macrophages recruited to phagocytose pathogens
- macrophages secrete cytokines to attract immune cells + proliferate the inflammatory response
- inflammatory response continues until wound is healed
What are the endocrine effects of pro-inflammatory cytokines?
(e.g. IL-1, TNF-a)
increase in catabolic hormones:
- increased ACTH and cortisol
- increased glucagon
- increased catecholamines
decrease in anabolic hormones:
- decreased growth hormone
- decreased insulin
What are the effects of cytokines IL-1, IL-6 and TNF on the inflammatory response?
- fibroblast proliferation (repair)
- fever
- endocrine effects - catabolic & anabolic
- anorexia
- T cell activation & B cell proliferation
- acute phase proteins
- metabolic effects (catabolic)
- local effects
- chemotaxis
- vasodilation
- cell adhesion proteins
What are the 5 cardinal signs of inflammation?
- heat
- redness
- swelling
- pain
- loss of function
In health, how long do glycogen stores maintain glucose concentration?
in health, glycogen stores can maintain [glucose] for up to 24 hours
How long does the brain survive after circulatory failure?
How does it store glycogen and what is its requirement?
the brain has NO glycogen store
obligate substrate is glucose and oxygen
(requirement = 120g/day which is equivalent to 1kg muscle)
it will not survive for more than 2 minutes of circulatory failure
it adapts to using ketones as an energy substrate
How long can the kidneys and liver survive after interruption of blood supply?
the kidneys and liver are capable of gluconeogenesis
they can survive for hours after interruption of blood supply
What substrates are used by the liver/kidney and skeletal muscle?
different tissues use different substrates
the liver & kidneys use fatty acids / amino acids
skeletal muscle uses glycogen stores / fatty acids
What are the first 2 phases that occur when the supply of oxygen and glucose is interrupted?
Phase 1 - glycogenolysis:
- glycogen is converted to glucose
- this lasts for 24 hours maximum
Phase 2 - gluconeogenesis:
- involves skeletal + secreted protein breakdown
- amino acids are converted to glucose + lactate production
How can blood lactate act as a prognostic marker in trauma?
failure of blood lactate to return to normal following trauma resuscitation carries a poor prognosis
What are the stages that can lead to refeeding syndrome?
- starvation / malnutrition
- glycogenolysis, gluconeogenesis and protein catabolism
- protein, fat, mineral and electrolyte/vitamin depletion - salt and water intolerance
- refeeding (switch to anabolism)
- fluid, salt, nutrients (CHO major energy source)
- insulin secretion
- increased protein and glycogen sysnthesis
- hypokalaemia, hypomagnesaemia, hypophophataemia, thiamine deficiency, salt/water retention (oedema) lead to refeeding syndrome
What is the cystic fibrosis transmembrane regulator (CFTR) protein?
What is its function and where is it found?
a cAMP dependent chloride channel
localises to the apical membrane of secretory and absorptive epithelial cells within the:
- airways
- pancreas
- liver
- intestine
- sweat glands and the vas deferens
What happens in lung disease where there is CFTR dysfunction?
- increased bacterial colonisation
- neutrophils accumulate
- elastase is secreted which digests lung proteins causing tissue damage
- dead neutrophils release DNA which increases the viscosity of the CF sputum
infection + persistent inflammatory state
