BEH Response Flashcards

Question

Describe Oxygen Deficiency and the affects on the brain

Answer 1

**Oxygen Deficiency** Hypoxia will occur with any interruption of normal respiration, pure hypoxia is the deprivation of oxygen with a maintained blood flow - Affects the brain quickly, leading to a depressant effect. Ongoing hypoxia leads to cell ischemia, dysfunction and injury, brain cell swelling, ICP increase, decreased blood flow, CPP decrease, increasing ischemia, brain cell death

Answer 2

**Uremia** Urine in the blood, often a clinical manifestation of renal failure, associated with fluid, electrolyte and hormone imbalances and metabolic abnormalities. Every organ becomes affected, leading to Uremic encephalopathy - Complications include, seizure, coma, cardiac arrest and death. Can also cause spontaneous bleeding from GI, subdural, or worsen bleeding due to trauma - Normal blood has ~ 20mg/L of urea in renal failure 800+mg/L

Answer 3

## Footnote Compression - of skull and contents Concussion - Brain shake Contusion - hematoma

Answer 4

**Traumatic Brain Injury** **Primary Injury** * Coup injury - at site of external force * Contra coup injury - opposite side of force where brain rebounds * Includes diffuse axonal injury lacerations and haemorrhage **Secondary Injury** * Post impact, often diffuse and multifocal * Includes infection, concussion and hypoxic brain injury as a result of reduced perfusion and increase in ICP

Answer 5

## Footnote **intracranial pressure** Within the cranium, Brain 80%, Blood tissue 10% CSF 10%. Normal ICP is 0-15mmHg. CSF acts as a small buffer for pressure, only 150mls so limited CPP = MAP - ICP Cerebral Perfusion Pressure is the pressure perfusing the brain - Normal 70-100mmHg - Less than 40 leads to brain ischemia MAP is DP + 1/3 pulse pressure ICP is normally 0-15mmHg A trauma event or illness cause increase in ICP, auto regulation starts to fail as ICP approaches MAP, CPP falls

Answer 6

**Auto-regulation of CPP** When injury or illness occurs, cerebral blood vessels dilate, increasing flow to injured area, increase cerebral blood volume, increasing ICP, dropping CPP A drop in CPP leads to a drop in O2 and glucose delivery, becoming ischemic Body compensates by increasing arterial blood pressure, dilating vessels to increase CPP, increases BP to increase MAP, however these add volume to the brain increasing ICP. Positive feed back!!! in a negative way BP will continue to increase, pulse pressure will widen, pt will eventually produce a reflex response of a drop in HR due to high BP It affects the breathing centres of the brain - triad of symptoms: * Widening pulse pressure with high BP * Bradycardia * Irregular breathing

Answer 7

**Hypothermia **\< 35c _Can result from, either or both:_ A decrease in heat production Increase in heat loss _Classification:_ Mild - 34 -36 C Moderate - 30 -34 C Severe below 30 C _Initially:_ * Vasoconstriction in peripheral vessels * Metabolism in CNS increases * BP, HR and RR all increase * Muscle tone increases - shivering - continues till 30c where glucose is depleted - when shivering is done, you cool quicker _Progression:_ * Decreases in RR, HR and BP * Circulating fluid drops as fluids shifts from the vascular space * Increase in urination * Arrthymias develop * ACS * CNS depression * Cardiac and respiratory arrrest

Answer 8

**Hyperthermia** 1. Temperature regulating mechanisms are overwhelmed by: * High temps in environment * Excessive exercise in moderate to extremely high temperatures 2. Temperature regulating centres of the body fail, usually in older adults or ill or incapacitated patients. Defined as core temp **\> 38c** - Body responds with tachypenea, Increased cardiac output- esp to muscle and skin, vasodilation, increase in sweat activity When regulatory mechanisms break down temp can increase to 41c +, **sings and symptoms** at this stage include: * Coma * Confusion * Irritability * Convulsions * Cerebral ischemia - stroke like * Tachycardia * Hyper ventilation

Answer 9

**Shock** Cardiogenic Shock Hypovolemic Shock Anaphylactic Shock Spetic Shock Neurogenic Shock

Answer 10

Shcok ## Footnote **Both**: Drop in BP, limited vascular functioning, can lead to brain ischemia and death **Transient**, fainting - changes in posture, environment, nutrition, hydration, emotion **Non transient** leads to ongoing BP drop, increased HR, pale cool clammy skin, and ACS - coma

Answer 11

**Stroke** 1. _Ischemic stroke_ - blood clot that blocks or plugs a vessel in the brain 2. _Hemorrhagic stroke_ - bleed **Signs and symptoms** * ACS * Unilateral facial drop * Unequal grip strength * Slurred speech * Unequal pupils * Elevated blood pressure * Dysphagia - difficulty swallowing * Dysphasia - difficulty talking

Answer 12

## Footnote Anything that starts displacing brain matter affects function and perfusion **CPP= MAP - ICP**