Pathophysiology Flashcards
What is Tpye 1 diabetes and DKA?
Type 1 diabetes occurs when there is a complete destruction of the pancreatic beta cells which are responsible for the release of insulin.
Insulin is responsible for the uptake of glucose into cells. It also inhibits the body from breaking down fat and using it as an energy source. Therefore this causes hyperglycaemia if not treated with insulin.
DKA occurs when a type 1 diabetic becomes significantly hyperglycaemic >20mmol.
This causes;
- dehydration/ hypovolemia from a mixture of osmotic diuresis and reduced oral intake/vomiting.
-metabolic acidosis. This is as the body begins to breakdown fat as a source of energy, this produces ketones, which are acidotic. This eventually leads to metabolic acidosis. In an attempt to rid the body of excess CO2 increased respirations occur (kussmauls resps).
What is type 2 diabetes a HONK?
Type to diabetes occurs when the effectiveness of insulin becomes reduced, this can due to insulin resistance or impaired insulin uptake.
HONK is profound hyperglycaemia without acidosis. As people with T2DM still have some insulin the breakdown of fat is inhibited. However due to the profound hyperglycaemia hypovolemia and dehydration can occur.
Due to polyuria and osmotic diuresis large amounts of fluid and electrolytes can be lost, causing hypovolemia.
To to the hyperosmolar state of the blood water is also drawn out of cells and into the blood causing dehydration and in some cases neurological symptoms such a seizures, hemiparesis and confusion.
Osmotic diuresis in in hyperglycaemia occurs as the kidney tubules become unable to absorb all the glucose, therefore it remains in the tubules impairs the kidneys ability to absorb water therefore it is all excreted.
What is Asthma?
Asthma is a inflammatory disease of the airways. It is characterised by mucous plugging, acute swelling and bronchoconstriction. It is completely reversible.
Asthma can be triggered by either extrinsic or intrinsic factors. Extrinsic asthma is caused by exposure to an allergen which enters the body and binds to IGE antibodies on mast cells and basophils. This causes mast cell degranulation and the release of inflammatory chemicals such as histamine. This causes mucus secretion and oedema. This inflammation then causes parasympathetic stimulation which causes bronchodilation.
Intrinsic asthma is caused by factors such as cold air, exercise or pollutants. Depending on the cause the pathophysiology differs, however bronchoconstriction is usually secondary to parasympathetic activation.
What is Anaphylaxis?
Anaphylaxis is a rapid onset, multiple-organ, generalised hypersensitivity (allergic) syndrome.
Upon subsequent exposures to an allergen the allergen enters the body and binds to the IGE antibodies on mast cells (connective tissue) and basophils (blood) and causes a release of inflammatory chemicals such as histamine, leukotrienes and prostaglandins. This inflammatory response results in widespread vasodilation and increased permeability of blood vessels.
An anaphylactic reaction must have systemic involvement and not just skin involvement.
This can be respiratory-bronchoconstriction, wheeze, tachypnoea.
Cardiovascular-tachycardia, hypotension, collapse.
Abdominal- cramps, diarrhoea, vomiting.
Shock
Is widespread inadequate perfusion at a cellular level.
It occurs secondary to changes in either myocardial function, intravascular volume and peripheral vascular resistance or distribution of blood flow.
physiological response to shock
Activation of sympathetic nervous system
Kidneys activate RAAS
angiotensin 2 causes widespread vasoconstriction.
aldosterone released- results in reabsorption of sodium, so more fluid in circulation and decreased urine output.
Andi-diuretic hormone- increases amount of water reabsorbed in kidneys and causes vasoconstriction.
Levels of shock
When cells do not have enough oxygen they must switch to anaerobic metabolism (energy production without oxygen). Anaerobic metabolism is less effective and short acting, it also produces metabolic by-products such as lactic acid. These result in impaired cellular function. This means organs function also becomes impaired. reducing function of the body. if not corrected cells begin to die, which dumps there contents into extracellular space.
Compensated shock The body is compensating SNS is working. -increased HR -increased RR -cool clammy skin -vasoconstriction -BP unchanged -decreased urine output Decompensated The body can no longer compensate -raped tachycardia -BP begins to drop from combination of rapid tachycardia and failure of compensatory mechanisms -altered LOC -delayed CRT Decompensated The body is in a state of metabolic acidosis, widespread cell death, organ failure and blood sludging. -unrecordable BP, falling HR, unconscious, very near death.
pneumothorax
air within the plural space. can be spontaneous or secondary to trauma. The pressure in the plural space is negative which allows the lungs to stay fully inflated. When air gets into the pleural space the pressure becomes positive and a section of the lung collapses.
Tension Pneumothorax
When a tear in the pleural space acts as a one way valve. The pressure in the plural cavity continues increasing compressing more and more lung. Eventually the pressure becomes so great that it impairs venous return to the right side of the heart.
VQ mismatch. Shunt vs Deadspace
A shunt occurs when there is adequate blood (perfusion) to the lungs however due to damage of the alveoli or fluid in alveoli O2 is not picked up- causes include pneumonia, CPO, pulmonary contusion ( as this can calling swelling and oedema.
Dead space occurs when there is a area of the lungs that do not receive blood supply so O2 is not picked up- causes include emphysema, PE, shock
Obstructive shock
When there is a blockage or compression in cardiopulmonary circulation which impairs the venous return to the heart. This causes a drop in cardiac output despite normal intravascular volume and myocardial function. tension pneumothorax, cardiac tamponade.
Septic shock
sepsis- occurs when bacteria enters the bloodstream and initiates an systemic inflammatory response. This causes release of inflammatory mediators such as cytokines and prostaglandins, this results in systemic inflammation, widespread vasodilation and increased blood vessel permeability. This causes a drop in intravascular volume and cardiac output.
As cardiac outut decreases perfusion cells must switch to anaerobic metabolism- this leads to metabolic acidosis.
As cardiac output continues to drop organs begin to loose perfusion and functionality which further worsens cardiac output.
The clotting cascade also becomes activated and disseminated intravascular coagulation can occur, worsening perfusion to vital organs.
When blood pressure begins to drop as a result of sepsis and becomes refractory to fluid bolus this is septic shock.
Is caused by inflammatory mediators released in response to severe infection which results in a loss of intravascular volume through blood vessel permeability, vasodilation and impaired cardiac function.
Sepsis occurs when a microorganism invades a sterile part of the body, which results in an immune response with systemic involvement.
This systemic involvement occurs when the bacteria enters the bloodstream. once in the blood stream an inflamtory response occurs and inflamatory mediators are released.
These inflammatory mediators cause, widespread vasodilation, increased capillary permeability and inflammation. This decreases cardiac output and myocardial function.
These inflammatory mediators can also stimulate the clotting cascade, which is an imbalance in procoagulation and anticoagulation factors leading to DIC.
Metabolic acidosis also occurs as cells must switch to anaerobic metabolism when they do not have enough oxygenation.
When sepsis continues widespread lack of perfusion occurs, multiple organ dysfunction occurs and metabolic acidosis, the body cannot not compensate.
When BP becomes refractory to fluids this is called as septic shock
cardiogenic shock
inability of the heart to pump effectively resulting in decreased cardiac output.
As the heart is unable to pump efficiently preload increases and blood begins to backlog and afterload also increases. This increase in afterload and preload causes coronary artery ischaemia which further worsens the hears ability to pump.
The drop in cardiac output means the body cannot receive adequate perfusion.
MI
Is caused by low cardiac output which results from the heart being unable to pump adequately. The most common cause is acute myocardial infarction, where the heart is no longer able to act effectively as a forward pump, leading to a backup of blood.`
Agitated Delirium
Agitation and delirium posing a risk to safety.
Also known as acute behavioral disturbance or excited delirium when there is a marked physiological derangement.
Agitation- is defined as an abnormal increase in motor activity- For example pushing grabbing, trying to climb off stretcher or actively resisting assessment, treatment or transport.
Delirium- signs of an abnormal state of mind- for example confusion, delusions, significantly abnormal behavior.
Differentials of agitated delirium
drugs recreational drugs infection metabolic disorders such as hypoglycemia, hyponatremia liver failure mental health condition dementia drug withdrawal alcohol -most common in NZ recreation drug use in particular amphetamines
