haemo exam revision Flashcards
What are three components of body fluids?
- Water
- Electrolytes
- Non-electrolytes
what is fluid as a percentage of body weight.
60% male
50% female
Infants 70-80%
Elderly 45%
Name the main intracellular and extracellular ions
- Intracellular = potassium
- Extracellular = sodium
What are the three areas within the extracellular fluid compartment?
- Intravascular
- Interstitial
*Transcellular
Describe third spacing
- Represents the loss or trapping of ECF in transcellular spaces
Give three examples of transcellular spaces
- CSF
- Peritoneal space –aka ascites
- Pleural space
- Pericardial cavities
- Joint spaces
- GI tract
What three interrelated processes do volume, solutes and pH balance within the body rely on?
- Fluid balance
- Electrolyte balance
- Acid base balance
Name three functions of electrolytes
- Regulate essential mineral and enzymes
- Control osmosis of water between body compartments
- Maintain acid/base balance required for normal cellular activities
- Create action potentials for neurotransmission
Describe the difference between electrolytes and non-electrolytes
Electrolytes are charged ions that dissolve in water. Non-electrolyte are compounds with
Describe the difference between simple diffusion and facilitated diffusion
- Facilitated diffusion is where the solute is attached to a lipid-soluble membrane carrier protein which facilitates the transport through what would otherwise be an impermeable membrane
Describe active transport
- Moves solutes against an osmotic gradient by using the sodium/potassium pump
What is the normal pH range of the human body?
7.35-7.45
Name two effects the change in pH has at a cellular level?
Disrupts the stability of the cell membranes
Alters protein structure
Name three different types of chemical buffer systems
- Phosphate, protein, bicarbonate
What are the two general causes of oedema?
- Abnormal leakage of fluid from the plasma to the interstitial spaces across the capillaries
- Failure of the lymphatic system to return fluid from the interstitium back to the intravascular space
Define osmolality
The concentration of a solution expressed as the total number of solute particles per kilogram (within the body
Name the four forces that contribute to Starlings equilibrium.
- Blood hydrostatic pressure (BHP)
- Blood (colloidal) osmotic pressure (BOP)
- Interstitial hydrostatic pressure (IHP)
- Interstitial (colloidal) osmotic pressure (IOP)
What does blood (colloidal) osmotic pressure do in the capillary?
Pulls fluid back into the capillary from the interstitial compartment As fluid moves in and out of the capillaries there is a small amount of excess fluid.
What system removes this and returns it to the circulation?
Lymphatic system
Describe what is meant by the 3:1 rule in association with blood loss and
fluid resuscitation
Infuse 300mL of crystalloid for every 100mL of blood lost to achieve fluid resuscitation
How much of the infused fluid will still be in the vascular space 1 hour post administration?
One third
Define the term colloid
A substance made up of larger particles that are unable to pass through the capillary membrane and thus remain in the intravascular space. The particles can be large molecules like proteins.
Name three different types of fluids can be used for volume resuscitation?
Isotonic crystalloids
Hypertonic crystalloids
Synthetic colloids
Blood substitutes
What is the name of the receptors that receive pain stimulation?
Nociceptors.
There are two types of nerve fibres that transmit pain? Name these and describe how they differ from each other
C – fibres: smaller and unmyelinated.
A delta fibres: Larger, myelinated – faster transmission.
Why do visceral organs such as the heart have dull heavy ache associated with them?
Served by C-fibre nociceptors.
Name the five steps associated with a combined approach to pain relief?
Reassurance
Distraction
Positioning
Splinting
Analgesia
List four pharmacodynamics of morphine.
Analgesia, decreased GI motility, respiratory depression, sedation, nausea and vomiting, miosis.
Explain why fentanyl is faster acting than morphine.
Fentanyl is more lipophilic and passes through cell membranes faster.
Explain why morphine causes hypotension, whereas fentanyl is less likely to.
Morphine causes more histamine release
Is naloxone an agonist or an antagonist?
Antagonist
Name five determinants of severity of blood loss
Other injuries
Volume lost
Patient’s perfusion status
Pre-existing conditions and co-morbidities
Patient’s age (weight)
Injuries – fractures / haematomas
Visible blood loss
Patient’s perfusion status
Pre-exisiting conditions
What is the blood volume mL/kg:
Infant - 90
Child age 5 - 80
Adult - 70
How much blood loss is associated with the following fractures:
Femur
Tib/fib
Humerus
Pelvis
1000-1500mL
400-700mL
200-700mL
>2000 mL
What are the percentage ranges that illustrate the four classes of haemorrhage
0-15%
15-30%
30-40%
> 40%
What is pulse pressure?
The difference between systolic and diastolic blood pressures
What is the normal ratio between systolic:diastolic:pulse pressure?
3:2:1
Name three conditions that a widened pulse pressure may indicate
Atherosclerosis.
Hyperthyroidism
Aortic valve regurgitation
Vigorous exercise
Pyrexia
TBI
Name three conditions that a narrowing pulse pressure may suggest
Hypovolaemia
Aortic stenosis
Mitral stenosis
Heart failure
Pericardial effusion
Pericardial tamponade
Describe what Mean Arterial Pressure is.
The average pressure in a patient’s arteries during one cardiac cycle.
What is the calculation for Mean Arterial Pressure (MAP)?
MAP = DBP + (SBP-DBP) 3
Define shock.
State of widespread hypoperfusion – typically due to reduced cardiac output
What volume of blood loss is associated with each stage of shock?
Compensatory – 15-30%
Decompensatory – 30-40%
Irreversible - >40%
Outline how the RAAS system works
Renal hypoperfusion causes sympathetic activation and stimulates release of renin
Renin converts Angiotensinogen to Angiotensin 1
Angiotensin 1 binds with ACE to become Angiotensin 2
Angiotensin 2 leads to: Vasoconstriction, Increased Sodium retention, Release of Aldosterone (More sodium retention) and release of ADH (Water reabsorption)
All of these promote CO as they increase Blood volume (Stroke volume) and Vascular resistance.
Name seven different types of shock
hypovolemic
Anaphylactic
Septic
Neurogenic
Hypoadrenal
Obstructive
Cardiogenic
Name three different causes of hypovolemic shock
Internal causes – peptic ulcer, AAA, TB, third space losses, fractures
Whole blood loss – haemorrhage
Plasma loss – burns,
Extracellular fluid loss – dehydration, vomiting, diarrhoea
Name three types of distributive shock
anaphylactic shock
septic shock
neurogenic shock
Many of the signs and symptoms of anaphylaxis can be attributed to a particular inflammatory mediator, what is this?
Histamine
What two different CPGs manage hypovolemic shock
Hypovolemia from uncontrolled bleeding
Hypovolemia from other causes
Name five etiologies of neurogenic shock including the most common
Spinal cord injury above T6 (most common)
TBI
Drugs
Hypoxia
Hypoglycaemia
Stroke
Brain cancer
Ectopic pregnancy
Miscarriage
Describe how whole blood loss affects haemodynamics
Reduced BHP
No change in BOP as whole blood is lost
Reduced preload
Reduced contractility
Reduced cardiac output
Activation of compensatory mechanisms
Recall of fluids from interstitial space
Recall of fluids from cells –dehydration
Reduced oxygen delivery –anaerobic metabolism –shock cascade
Describe the difference between spinal shock and neurogenic shock
Neurogenic shock describes the hemodynamic changes following SCI,
whereas spinal shock is characterized by a reversible reduction of sensory, motor, or reflex function of the spinal cord below the level of injury
Why does vasodilation occur in neurogenic shock?
The loss of innervation of the sympathetic nervous system (SNS)(which triggers vasoconstriction) due to injury in either the brain or spinal cord.
As there is still parasympathetic innvervation via the vagus nerve (which triggers vasodilation) and there is no opposition from the SNS below the site of the injury, vasodilation is seen below the injury site
Describe spinal shock
A temporary loss of all voluntary and reflex neurologic activity below level of injury and presents as sensory and motor function such as flaccidity and paralysis, and loss of reflexes below the level of the spinal cord injury
Describe how adrenaline treats the signs and symptoms of anaphylaxis
alpha 1 – causes vasoconstriction addresses vasodilation, capillary leak reducing swelling and oedema, increases BP and hence venous return increasing SV and CO, reduces airway swelling, stridor
Beta 1 – increases HR, contractility and conduction, improving HR, SV & CO
Beta 2 – bronchodilation and mast cell stabilization, improving airway and gas exchange and stops the release of inflammatory mediators
What is warm shock and what is cold shock?
Warm shock is a hyperdynamic acute response to sepsis. It usually begins within hour of onset of inflammation or infection. It occurs when the patient is compensating and presents with the patient warm, flushed as a result of massive vasodilation and increased capillary permeability. HR is increased as a result of catecholamine response and tachypnea occurs due to increased myocardial oxygen demand.
Cold shock occurs later after 6-72 hours depending on the patient and situation. The patient presents as ‘shut down’ with vasoconstriction occurring, sludging, pale cool clammy skin and reducing LOC. It indicates that the patient is no longer able to compensate.
Name two causes of adrenal insufficiency. Explain why these conditions are of concern
Addisons disease
Congential adrenal hypoplasia
Describe the pathophysiology of a tension pneumothorax
Air enters the pleural cavity unilaterally with each inspiration and is unable to move out during expiration.
Therefore the volume and pressure of air within the pleural cavity increases over time.
The increased pressure causes the ipsilateral lung to collapse (atelactesis), reducing ventilation and gas exchange.
In addition the increased intrathoracic pressure starts to occlude the inferior vena cava reducing venous return.
This may be exacerbated by mediastinal shift of thoracic contents.
As venous return is reduced, stroke volume is reduced and the heart is pumping but without volume, reducing cardiac output and causing shock.
As venous return is impaired jugular veins will distend.
The increased air will cause hyperresonance on the affected side on percussion and with atelectasis reduced or absent lung sounds will be heard.
The increased pressure causes air to seep out of the pleural cavity into the sub dermal spaces causing subcutaneous emphysema. The mediastinal shift may cause tracheal deviation.
Under which protocol should you treat obstructive shock?
Hypovolemia from other causes
two factors that lead to disruptive shock
- decrease in sympathetic control
- increase in vasodilation
