Multi-Organ Failure, Aging, & Death Flashcards
Defintion: Occurs when too little circulating blood volume causes a decrease in mean arterial pressure (MAP), resulting in the body’s need for oxygen being unmet.
hypovolemic shock
What are some causes of hypovolemic shock?
- hemorrhage (internal or external)
- Vomiting
- Diarrhea
- Bowel obstruction, pancreatitis
- Burns
- Neglect, environmental (dehydration)
Definition: results when fluid volume moves out of vascular space into extravascular space; “third spacing”
relative hypovolemia
Definition: loss of intravascular fluid volume
absolute hypovolemia
What are some causes of cariogenic shock?
- Myocardial infarction
- Left ventricular failure
- Right ventricular failure
- Myocardial contusion (trauma)
- Cardiomyopathy
- Myocarditis
- Septic myocardial depression
- Valvular failure (stenotic or regurgitant)
- Hypertropic cardiomyopathy
- Ventricular septal defect
- Electrical failure (arrhythmic)
- Bradycardia/Tachycardia
Why does there seem to be an increase in cancer among older patients?
declining function of tumor suppressor genes, particularly P53, which normally triggers apoptosis in cells that have undergone DNA-damaging stress
What abnormalities in post-translational changes can cause aberrant proteins in older people?
Glycosylation – adding of carbohydrate groups changes protein function. Abnormalities in this process increases with age.
Cross-linking of various types of macromolecules can also alter their function.
Defintion: the idea that some cells are programmed to replicate a finite number of times
program theory
What happens to connective tissue with age?
Cross-linking of connective tissue causes a decrease in the elasticity of connective tissues, and has effects on many organs; happens to both collagen and elastin
Definition: stretches of repetitive DNA at the ends of chromosomes
telomeres
How does telomere shortening contribute to aging?
Since the chromosome cannot be completely copied, the very tips of each chromosome get shorter and shorter with successive cell divisions. When the telomere gets too short for the cell to divide, it either undergoes apoptosis (programmed cell death) or it become senescent – it stops dividing. Enzyme telomerase activity drops with age.
Definition: an enzyme that creates new blocks of repetitive DNA sequences, which are added to the tips of the chromosomes, keeping the telomeres from shortening.
telomerase
Cells that have a high turnover rate have high levels of telomerase. How does increasing telomerase affect tissue?
One study showed that elevating levels of telomerase in the skin and hair follicles of mice caused them to have healthier skin, better wound healing, and thicker fur. However, they also had a higher rate of skin cancer.
Definition: The theory that all systems have a certain amount of reserve capacity, and when the capacity is exhausted, due to injury or damage, the system begins to fail.
Wear and Tear Theory
Definition: various materials accumulate in tissues, and this influences their function.
(ex. collagen between myocardial cells, calcium in many different tissues, amyloid in brain cells)
Excessive Accumulation Theory
How does aging affect the immune system?
- both innate and adaptive immunity decline, but adaptive immunity is particularly impaired
- older people are less likely to develop fevers; less robust immune response
- more vulnerable to disease, and slower to recover
- less responsive to vaccines – need a stronger version of the flu vaccine
How does aging affect responsiveness to temperature?
- less vascular control (to conserve heat)
- loss of subcutaneous fat and hair and thinning of skin increase the rate of heat loss
- less able to exercise to generate heat
- less effective at shivering
- sweating is less effective – sweat glands become fibrotic and function less well
How does aging affect the heart?
- the heart is typically remains unchanged or undergoes moderate hypertrophy
- left ventricular wall typically thickens to some extent Igreater in a person with hypertension)
- possible enlargement of the left atrium and of the left ventricular cavity
- thickening of the myocardial wall due to an increase in the size of individual cardiac myocytes
- some replacement of myocytes with fibrous tissue
How does aging affect vasculature?
- the walls of their large distributing arteries thicken and arteries become dilated and elongated (result of cellular accumulation and deposition of matrix in the intimate)
- fragmentation of the elastic fibers
- increased the risk of atherosclerosis
- changes in the connective tissue within the media of the vessel wall decrease its elasticity
- increase in collagen and changes in the cross-linking of collagen
- elastin becomes frayed and fragmented
How does aging affect cardiac function at rest?
- rate of filling of the left ventricle during diastole is slower, (slowed relaxation of the muscle)
- resting arterial blood pressure tends to increase with age, thereby increasing the afterload
- force of conctraction is not changed in a normal heart
- rate of relaxation is decreased, due to slower pumping of Ca++ back into the sarcoplasmic reticulum.
- resting ejection fraction is unchanged in healthy men and women
- resting stroke volume increases slightly in older men
- supine heart rate is unchanged, but heart rate while sitting decreases slightly
- intrinsic sinus rate (the heart rate in the absence of sympathetic and parasympathetic neural input) drops slightly
- small fall in CO due to the fall in HR in women
How does aging affect cardiac function during exercise?
- maximal cardiac output decreases by 25%.
- peripheral oxygen utilization falls as a result of age-associated reductions in muscle mass and strength
- less of an increase in SV with increased EDV.
How does aging affect the respiratory system?
- loss of elastic tissue –> loss of elastic recon
- respiratory muscles weaken
- chest wall becomes stiffer due to calcification of intercostal cartilage
- decrease in VC and increase in RV
- decreased airflow
- FEV1 falls by about 23-30 ml/year
- diffusion capacity peaks at age 20 then declines due to alveolar destruction, increased alveolar wall thickness, and small airway closure
- PaO2 declines until age 75
- control of breathing declines due to decreased responsiveness of peripheral and central chemoreceptors
What is the effect of aging on the renal system?
- GFR and renal blood flow declines progressively (10%/decade after 30) due primarily to a decreased size of the renal vascular bed
- tubular function is maintained
- renin levels are 30-50% lower in the elderly
- lower aldosterone levels due to lower renin/angiotensin levels
- less able to conserve sodium when on a salt-restricted diet –> increased risk of volume depletion and dehydration
- higher risk for hyperkalemia
- renal concentrating and diluting ability is compromised
- thirst mechanisms appear to be less sensitive.
- secretory mechanisms are impaired, which can interfere with the normal clearance of drugs
Definition: irreversible loss of all brain activity, including those essential for life
brain death
Definition: a state lacking wakefulness and awareness
coma
Definition: an “awake” state that lacks awareness; about 50% of
adults and 60% of children regain consciousness within 6 months; after 1 year, likelihood of recovery is much lower
vegetative state
Defintion: one or more devices or procedures that keep a patient alive. Includes mechanical ventilation, feed tubes, dialysis, heart-lung bypass, etc.
life support
What is cachexia?
often seen in cancer patients; a set of metabolic changes that results in loss of weight, particularly muscle mass, compounding the consequences of loss of appetite
Definition: a pattern of increasingly shallow breaths, followed by a brief cessation of breathing, followed by a few strong deep breaths. The pattern repeats itself until the patient stops breathing
Cheyne-Stokes breathing
Defintion: resonant sounds due to fluid accumulation deep in the lungs
Death rattle
What are some characteristics that are present 48 hours before death or “active dying”?
- Cheyne-Stokes breathing
- death rattle
- loss of appetite and thirst
- sweating – clammy skin
- fall in body temperature of 1-2 degrees
- mottled skin, especially at extremities reflecting circulatory failure
Defintion: just providing appropriate comfort care for a dying patient; this might be just food and water and pain medication for a patient who in their last weeks of life.
palliative care
Defintion: focuses on providing comfort care through the dying process, and on meeting the emotional and spiritual needs of patients and their families; patients may be cared for in their homes or in home-like institutional settings
hospice care
When is hospice care appropriate?
for people whose terminal illness progresses in a predictable way
What are the top 4 causes of death in the US?
- heart disease
- cancer
- chronic lower respiratory disease
- stroke
