Metabol 3) Response to sepsis vs starvation Flashcards
What are the 2 basic differences between simple starvation and catabolic weight loss?
Simple starvation has metabolic adaption and lean tissue is conserved.
Catabolic weight loss has no adaption and lean tissue breakdown continues despite nutrient intake
What is the difference between basal metabolic rate in simple starvation vs starvation superimposed onto injury?
Decreased in both
What is the difference between glucose levels in simple starvation vs starvation superimposed onto injury?
Simple starvation: low
Starvation superimposed onto injury: high
What is the difference between glucose utilisation in simple starvation vs starvation superimposed onto injury?
Simple starvation: limited glucose use
Starvation superimposed onto injury: increased glucose use
What is the difference between gluconeogenesis in simple starvation vs starvation superimposed onto injury
Simple starvation: increased initially, decreased after 5-7 days
Starvation superimposed onto injury: increased
What is the difference between protein catabolism in simple starvation vs starvation superimposed onto injury?
Simple starvation: low
Starvation superimposed onto injury: high
What is the difference between fat catabolism in simple starvation vs starvation superimposed onto injury?
Simple starvation: high
Starvation superimposed onto injury: low / none
What is the difference between ketone utilisation in simple starvation vs starvation superimposed onto injury?
Simple starvation: increased
Starvation superimposed onto injury: decreased
What is the difference between ketosis in simple starvation vs starvation superimposed onto injury?
Simple starvation: present
Starvation superimposed onto injury: absent
What is anorexia nervosa?
Severe restriction of nutritional intake causing severe nutritional deficiency
Describe the consequences of low glucose caused by anorexia nervosa
Low glucose causes declines in insulin and increased glucagon release resulting in degradation of glycogen, fat stores and protein.
Brain adapts to use ketones
Describe what happens to the fat tissue in anorexia nervosa
High glucagon activates hormone-sensitive lipase
Breakdown of TG to FFA
What can cause ketoacidosis?
Diabetes ketosis
Fasting ketosis
Alcoholic ketoacidosis
Describe alcoholic ketoacidosis
Characterised by hyperketonaemia and metabolic acidosis without significant hyperglycaemia.
Ethanol is metabolised to acetic acid (ketone)
Describe the mechanism of ketosis
Liver produces ketones which is stimulated by low insulin and high glucagon.
Activation of lipase.
Fatty acids transported to liver, enter mitochondria and are oxidised to acetyl CoA.
Enter Krebs cycle to generate ATP or generates ketones
What would the level of ketones be in mild ketosis after a 12 hour fast?
1mmol/L
What would the level of ketones be after fasting for 20 days?
8-10mmol/L
What 3 stabilisation methods occur in ketosis?
Stimulation of insulin release despite low glucose
Increased sensitivity of adipose tissue to insulin inhibitory effect on fatty acid release
Direct inhibition of lipolysis by ketones
What are ketones?
A water-soluble, fat-derived fuel that is used when glucose is low.
What tests should be done when considering sepsis?
Blood gas Lactate Glucose Blood culture FBC CRP Na+ K+ Cl- HCO3- eGFR AKI staging Phosphate Calcium Albumin Magnesium Coagulation LFT
What are some severe consequences of lactic acid production?
Hypovolaemia
Cardiac failure
Sepsis
Cardiopulmonary arrest
Describe the hyper-metabolic response to injury
Increased BP and HR Peripheral insulin resistance Increased protein and lipid catabolism Increased resting energy expenditure Increased body temperature Total body protein loss Muscle wasting Acute-phase protein response
What are the causes of hyperglycaemia in critical illness?
Stress mediators oppose anabolic actions of insulin
Enhanced adipose tissue lipolysis
Enhanced skeletal muscle proteolysis
High catecholamines and cortisol
Why does lean muscle protein breakdown occur in illness?
Pro-Inflammatory cytokines such as TNF
Reduced ability to use lipids as energy
What is the consequence of a 10% loss in lean body mass?
Increased infection Delayed wound healing Muscle weakness Prolonged mechanical ventilatory utilisation Inhibits cough reflex Delays mobilisation
Describe some endocrine complications of starvation
Hypothalamic-pituitary abnormalities Hypogonadotropic, hypogonadism Low GnRH, LH, FSH, oestradiol Amenorrhoea, infertility Thyroid problems
