Transcript Blood pressure

Acute Care Workshop
Dr Stephanie Sim
Dr Sharon Christie
Dr James Shaw
Dr Lysa Owen
Plan for today
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Learning Objectives
Powerpoint presentation (on Blackboard)
Demonstration of ABCDE
Split into 2 groups
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Simulation
Break at half time then swap
Outcomes Acute care Workshop
Describe the pathophysiology of hypoxia
and hypotension
 Identify when a patient is acutely unwell
 Demonstrate ability to assess an acutely
unwell patient using ABCDE
 Initiate appropriate management
 Demonstrate awareness of specific
treatment regimens
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Hypoxia
Oxygen cascade
• Series of steps: atmospheric air
•
pO2 at any stage
mitochondria
in subsequent steps
25
Dry atmospheric gas,
(~21)
20
15
pO2
(kPa)
Humidified tracheal
gas, (~19.8)
Alveolar gas, (~14)
Arterial blood, (~13.3)
10
Capillary blood, (~7)
5
Mitochondria, (~4)
0
Remember
Context is really important….
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A patient with ‘normal values’ when breathing at a rate
of 40 bpm, is not as well as someone breathing at a
rate of 12bpm
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A patient with Sats of 96% on 60% O2 is not as well as
someone breathing air with the same O2 sats!
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A patient with PaO2 of 9kPa is getting better if it was 8
before and he is on the same concentration of O2,but
getting worse if it was previously 10kPa!
Blood pressure
Related to
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Arterial & venous system with organ autoregulation
Blood Pressure
Cardiac Output (CO) X Systemic vascular resistance (SVR)
Heart Rate X Stroke Volume
Blood pressure
Related to
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Arterial & venous system with organ autoregulation
Blood Pressure
Myocardial contractility ↓↓
CARDIOGENIC SHOCK
Afterload ↓↓ SEPSIS/
ANAPHYLAXIS/
NEUROGENIC
Cardiac Output (CO) X Systemic vascular resistance (SVR)
Heart Rate X Stroke Volume
Preload ↓↓HYPOVOLAEMIA/ HAEMORRHAGE
Blood pressure
THEREFORE
 Blood Pressure depends on
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Circulating blood volume
 ↓ in hypovalaemia/ haemorrhage
Pump function
 ↓ in cardiogenic shock
Systemic vascular resistance
 ↓ in sepsis
 ↓ in anaphylaxis
Response to shock
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Tachycardia, Tachypnoea
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Progressive peripheral vasoconstriction
(if possible)
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Shift to anaerobic metabolism for hypoxic
cells, then lose the ability to generate
ATP, loss of electrical gradient and cell
death
Causes of Shock
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Haemorrhagic (70Kg man)
Class I
Class II
Class III
Class IV
Blood loss (ml)
Up to 750
750-1500
1500-2000
>2000
Blood loss
(% volume)
Up to 15%
15-30%
30-40%
>40%
Pulse rate
<100
>100
>120
>140
Blood pressure
Normal
Normal
Decreased
Decreased
Pulse pressure
Normal or
increased
Decreased
Decreased
Decreased
Respiratory Rate
14-20
20-30
30-40
>35
Urine Output ml/hr
>30
20-30
5-15
Negligible
CNS/Mental status
Slightly
anxious
Mildly
anxious
Anxious,
confused
Confused,
lethargic
Signs of shock
Tachycardia, tachypnoea and vasoconstriction
=> Diagnosis of shock until proven otherwise
(relying on BP drop delays diagnosis)
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Urine output – indicator of renal blood flow
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Relative to normal (kids, young adults, elderly)
Varying ability to mount response (B blocker, Ca
channel blocker, paced, etc)
Should be >0.5ml/Kg/hour
Acid Base Abnormality
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Respiratory alkalosis initially> Metabolic Acidosis
Assessment of shock
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Airway
Breathing – give O2, RR, SpO2, Breath Sounds
Circulation – stem bleeding/obtain adequate iv
access/assess tissue perfusion (P,BP,CRT) ?Fluids
required (likely to be)
Disability – AVPU, BM, Pupils
Exposure – Complete examination re possible
cause, temp, TPAR
?Catheterisation
Fluid Homeostasis
Normal 70 Kg male = 42litre (60%) Water
Extracellular
Intracellular Fluid (ICF)
28 litres
Fluid (ECF)
9.4
litres
4.6
litres
Interstitial
Plasma
Normal Physiology
Compartment volume maintained by
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Oncotic pressure (retains fluid)
Hydrostatic pressure (forces fluid out of vessel)
Osmotic gradients
Electrolyte pumps
Types of fluid replacement
 Crystalloids
 Colloids
 Blood
Crystalloids
Eg. Dextrose, Saline, Hartmans
True solutions - substances which will diffuse through
a semi-permeable membrane
Pros/Cons:
Easily available
 Cheap
 Variable volume of distribution (can end up in undesirable
spaces!)
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Colloids
Eg. Gelofusine,
“glue” – Greek
Substance which does not diffuse through a
semipermeable membrane.
Large particles (protein or carbohydrate) that are
suspended in water
Pros/Cons :
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Stays in intravascular space
Relatively expensive
Risk of anaphylaxis
No proven benefit over saline in hypovolaemia
Blood
Pros/Cons : Well recognised
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Replaces ‘like with like’
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Carries oxygen well!
Expensive
Risk of transfusion reactions
Infection risk etc
Distribution of Fluids
5%Dextrose
(essentially WATER)
Circulation
Interstitial Fluid
ICF
ECF
0.9% Saline
Blood
Colloid (expands plasma
volume due to oncotic pressure)
Main points
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Recognise patient is unwell
Treat early (ideally before hypoxic, hypotensive)
Optimise what you can (ABCDE)
*Remember Oxygen*
General measures to improve blood pressure
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*Fluids* ( in almost all cases)
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Inotropes
Specific measures to treat cause
Monitor response
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Urine output, ABGs
Blood pressure/ cardiac monitor
Central lines etc
Etc
Any Questions?
Outcomes Acute care Workshop
Describe the pathophysiology of hypoxia
and hypotension
 Identify when a patient is acutely unwell
 Demonstrate ability to assess an acutely
unwell patient using ABCDE
 Initiate appropriate management
 Demonstrate awareness of specific
treatment regimens
