Upload
michael-robbins
View
218
Download
0
Tags:
Embed Size (px)
Citation preview
1
SHOCK
Prof.M.H.MUMTAZ
2
SHOCK
Inadequate perfusion (blood flow) leading to inadequate oxygen delivery to tissues
3
Physiology
Basic unit of life = cell Cells get energy needed to stay
alive by reacting oxygen with fuel (usually glucose)
No oxygen, no energy No energy, no life
4
Aerobic Metabolism
6 O2
GLUCOSE
METABOLISM
6 CO2
6 H2O
36 ATP
HEAT (417 kcal)
5
Anaerobic Metabolism
GLUCOSE METABOLISM
2 LACTIC ACID
2 ATP
HEAT (32 kcal)
6
Anaerobic? So What?
InadequateInadequateCellularCellular
OxygenationOxygenation
InadequateInadequateCellularCellular
OxygenationOxygenation
AnaerobicAnaerobicMetabolismMetabolism
AnaerobicAnaerobicMetabolismMetabolism
MetabolicMetabolicFailureFailure
MetabolicMetabolicFailureFailure
MetabolicMetabolicAcidosisAcidosis
MetabolicMetabolicAcidosisAcidosis
InadequateInadequateEnergyEnergy
ProductionProduction
InadequateInadequateEnergyEnergy
ProductionProduction
Lactic AcidLactic AcidProductionProduction
Lactic AcidLactic AcidProductionProduction
Cell Death!Cell Death!Cell Death!Cell Death!
7
Homeostasis is maintenance of balance
Requires proper functioning systems• Cardiovascular• Respiratory• Renal
8
Cardiovascular System
Transports oxygen, fuel to cells Removes carbon dioxide, waste
products for elimination from body
Cardiovascular system must be able to maintain sufficient flow through
capillary beds to meet cell’s oxygen and fuel needs
9
Flow = Perfusion
Adequate Flow = Adequate Perfusion
Inadequate Flow = Indequate Perfusion
(Hypoperfusion)
Hypoperfusion = Shock
10
What is needed to maintain perfusion?
Pump Pipes Fluid
Heart
Blood VesselsBlood
11
How can perfusion fail?
Pump Failure Pipe Failure Loss of Volume
Factors Affecting The Pump
Factors Affecting The Pump
Preload Contractile force
• Frank-starling mechanism Afterload
Preload Contractile force
• Frank-starling mechanism Afterload
13
Muscle Anatomy
14
Contraction: Sliding Filaments
image from: http://www.accessexcellence.com/AB/GG/muscle_Contract.html
What Is Blood Pressure?What Is Blood Pressure?
BP = COxSVR
BP = COxSVR
CO = Stroke VolumeCO = Stroke VolumeX Heart RateX Heart Rate
SVR= B.vessel calibre +viscositySVR= B.vessel calibre +viscosity
CO = Stroke VolumeCO = Stroke VolumeX Heart RateX Heart Rate
SVR= B.vessel calibre +viscositySVR= B.vessel calibre +viscosity
16
What Affects Blood Pressure?
ANS balance Contractility
• Preload• Starling’s law
Afterload
17
Types of Shock and Their Causes
CARDIOGENICHYPOVOLAEMIC
SEPTICNEUROGENICPSYCHOGENic
obstructiveANAPHYLACTIC
18
Cardiogenic Shock
Pump failure Heart’s output depends on
• How often it beats (heart rate)• How hard it beats (contractility)
Rate or contractility problems cause pump failure
19
Cardiogenic Shock
Causes• Acute myocardial infarction• Very low heart rates (bradycardias)• Very high heart rates (tachycardias)
Why would a high heart rate caused decreased output?
Hint: Think about when the heart fills.
20
Neurogenic Shock
Loss of peripheral resistance Spinal cord injured Vessels below injury dilate
What happens to the pressure in a closed system if you increase its size?
21
Hypovolemic Shock
Loss of volume Causes
• Blood loss: trauma• Plasma loss: burns• Water loss: Vomiting, diarrhea, sweating,
increased urine, increased respiratory loss
If a system that is supposed to be closed leaks, what happens to the pressure in it?
22
Psychogenic Shock
Simple fainting (syncope) Caused by stress, pain, fright Heart rate slows, vessels dilate Brain becomes hypoperfused Loss of consciousness occurs
What two problems combine to produce hypoperfusion in psychogenic shock?
23
Septic Shock
Results from body’s response to bacteria in bloodstream
Vessels dilate, become “leaky”
What two problems combine to produce hypoperfusion in septic shock?
24
Anaphylactic Shock
Results from severe allergic reaction Body responds to allergen by releasing
histamine Histamine causes vessels to dilate and
become “leaky”
What two problems combine to produce hypoperfusion in anaphylaxis?
25
OBSTRUCTIVE SHOCK
PUMONARY EMBOLISM ?
CRDIAC TEMPONADE ?
PNEUMOTHORAX ?
26
Shock:Signs and Symptoms
Restlessness, anxiety
Decreasing level of consciousness
Dull eyes Rapid, shallow
respirations
Why are these signs and symptoms present? Hint: Think hypoperfusion
Nausea, vomiting Thirst Diminished urine
output
27
Shock: Signs and Symptoms
Hypovolemia will cause• Weak, rapid pulse• Pale, cool, clammy skin
Cardiogenic shock may cause:• Weak, rapid pulse or
weak, slow pulse• Pale, cool, clammy skin
Neurogenic shock will cause:• Weak, slow pulse• Dry, flushed skin
Sepsis and anaphylaxis will cause:• Weak, rapid pulse• Dry, flushed skin
Can you explain the differences in the signs and symptoms?
28
Shock: Signs and Symptoms
Patients with anaphylaxis will:• Develop hives (urticaria)• Itch• Develop wheezing and difficulty
breathing (bronchospasm)
What chemical released from the body during an allergic reaction accounts for these effects?
29
Shock: Signs and Symptoms
Shock is NOT the same thing as a low blood pressure!
A falling blood pressure is a LATE sign of shock!
30
Treatment
Secure, maintain airway Apply high concentration oxygen Assist ventilations as needed Keep patient supine Control obvious bleeding Stabilize fractures Prevent loss of body heat
31
Treatment
Elevate lower extremities 8 to 12 inches in hypovolemic shock
Do NOT elevate the lower extremities in cardiogenic shock
Why the difference in management?
32
Management of Shock
Shock begins when DO2 to the cells is inadequate to meet metabolic demand
The major therapeutic goals in shock therefore are sufficient tissue perfusion and oxygenation
Early diagnosis remains a major problem
33
Treatment
Administer nothing by mouth, even if the patient complains of thirst
34
Hemodynamic Characteristics in Different Types of Shock
Type Preload CO PVR SVR
Hemmorrhagic LOW
Anaphylactic LOW
Cardiogenic HIGH
Septic (Hyperdynamic)
LOW
Septic (Hypodynamic)
LOW
/
35
Inotropic Agents and Vasodilators
Vasoactive drugs are an important pharmacologic defense in the treatment of shock.
May be required to support BP in the early stages of shock.
These agents may be needed to:• Enhance CO through the use of inotropic
agents• Increase SVR through the use of vasopressors
36
Effects of Inotropic Agents and Vasodilators
Epinephrine 0.02 – 0.5
Norepinephrine
0 - 0.05 – 0.5
Dopamine DR 2 -12
Dobutamine
2 - 12
Dopexamine
DR 0 - 0.9 - 5
Vasopressin Angiotensin III
5 - 20
Amrinone PDI 5 -10
Drug Receptor CO SVR Dose Range
0 -
(g/kg/min)
1
37
Effects of Inotropic Agents and Vasodilators
Nifedipine 0 - 0.5 - 10
Nitroglycerin 0 - 3 - 5
Nitroprusside 0 - 0.5 - 5
Prostacyclin 10 - 40
2
Drug CO SVR Dose Range
(g/kg/min)
38
Dopamine An endogenous precursor of norepinephrine with
multiple dose-related effects
Low Dose (0.5 - 3 mg/kg/min)2 and dopaminergic (DR) effects
• Enhanced blood flow to renal and splanchnic beds
Moderate Dose (5 -10 mg/kg/min)• Positive inotropic effects
High Dose (>20 mg/kg/min)-actions (vasoconstriction)
39
MANAGEMENT GUIDE
1,Haemodynamic monitoring Blood pressure/HR SV,HR,CI,CO SVR,SVRI TOOLS ; SWAN GANZ TEMPERATURE LIDCO CENTRAL VENOUS PRESSURE
2, OXYGENATION STATUS FIO2/PAO2/PaO2/DO2/VO2/ Lactate
3, ACID BASE STATUS
40
HAEMODYNAMIC TRUTHS
1,TACHYCARDIA IS NEVER AGOOD THING. 2,HYPOTENSION IS ALWAYS PATHOLOGIC 3,THERE IS NO SUCH THING AS NORMAL CARDIAC OUTPUT. 4,CENTRAL VENOUS PRESSURE IS ONLY ELEVATED IN DISEASE. 5,PERIPHERA EDEMA IS OF COSMETIC
CONCERN.
PINKSY..Chest.2007; 132;2020-2029
41
Bleeding
42
Bleeding Significance
If uncontrolled, can cause shock and death
43
Identification of External Bleeding
Arterial Bleed • Bright red• Spurting
Venous Bleed• Dark red• Steady flow
Capillary Bleed• Dark red
• Oozing
What is the physiology that
explains the differences?
44
Control of External Bleeding
Direct Pressure• gloved hand• dressing/bandage
Elevation Arterial pressure points
45
Arterial Pressure Points
Upper extremity: Brachial Lower extramity: Femoral
46
Control of External Bleeding
Splinting• Air splint• Pneumatic antishock garment
47
Control of External Bleeding
Tourniquets• Final resort when all else fails• Used for amputations• 3-4” wide• write “TK” and time of application on
forehead of patient• Notify other personnel
48
Control of External Bleeding
Tourniquets• Do not loosen or remove until
definitive care is available• Do not cover with sheets, blankets,
etc.
49
Epistaxis
Nosebleed Common problem
50
Epistaxis
Causes• Fractured skull• Facial injuries• Sinusitis, other URIs• High BP• Clotting disorders• Digital insertion (nose picking)
51
Epistaxis
Management • Sit up, lean forward• Pinch nostrils together• Keep in sitting position• Keep quiet• Apply ice over nose• 15 min adequate
52
Epistaxis
Epistaxis can result in life-threatening blood loss
53
Internal Bleeding
Can occur due to:• Trauma• Clotting disorders• Rupture of blood vessels• Fractures (injury to nearby vessels)
54
Internal Bleeding
Can result in rapid progression to hypovolemic shock and death
55
Internal Bleeding
Assessment• Mechanism?• Signs and symptoms of hypovolemia
without obvious external bleeding
56
Internal Bleeding
Signs and Symptoms•Pain, tenderness, swelling,
discoloration at injury site•Bleeding from any body orifice
57
Internal Bleeding
Signs and Symptoms• Vomiting bright red blood or coffee
ground material• Dark, tarry stools (melena)• Tender, rigid, or distended abdomen
58
Internal Bleeding
Management• Open airway• High concentration oxygen• Assist ventilations• Control external bleeding• Stabilize fractures• Transport rapidly to appropriate facility