(2) Approach to Shock Flashcards

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1
Q

Definition of shock

A

Circulatory shock: an abnormality of the circulatory system that results in reduced organ perfusion and tissue oxygenation

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2
Q

causes of shock are broadly caused by

A
  • reduced cardiac output e.g. hypovolaemic, cardiogenic, obstructive
  • reduced systemic vascular resistance e.g. septic shock, anaphylactic shock
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3
Q

summary of 4 main types of shock

A

CHOD
Cardiogenic
Hypovolaemic
Obstructive
Distributive

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4
Q

causes of hypovolaemic shock

A
  • haemorrhage
  • vomiting
  • diarrhoea
  • diuresis e.g. post catheter
  • burns
  • third spacing e.g. pancreatitis, severe sepsis, anaphylaxis)
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5
Q

causes of cardiogenic shock

A
  • Myocardial infarction
  • Cardiomyopathy
  • Cardiac arrhythmia
  • Tachy or brady
  • Negatively inotropic drug overdose (e.g. beta blockers or CCB)
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6
Q

cause sof Obstructive shock

A
  • Tension pneumothorax
  • Massive PE
  • Cardiac tamponade
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7
Q

causes of Reduced systemic vascular resistance (SVR):

A
  • Septic shock
  • Anaphylactic shock
  • Neurogenic shock
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8
Q

why treat shock as early as possible

A
  • Effects of shock are initially reversible, but rapidly become irreversible, resulting in multiorgan failure and death
  • Initiate treatment early
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9
Q

Features of shock

A
  • Hypotension
  • Tachycardia
  • Oliguria
  • Abnormal mental state
  • Tachypnoea
  • Cool, clammy, cyanotic skin]
  • Metabolic acidosis
  • Hyperlactatemia
  • Others
    o Chest pain and ECG changes e.g. anterior wall MI
    o Fever and cough or history of ongoing UTI
    o RTA and patient has head and spinal cord injuries, quadriparesis and paraplegia
    o History of insect bite, lip swelling and rash
    o Central abdominal pain, patient unresponsive
    o Abdominal pain, vomiting and diarrhoea since 3 days
    o History of AF, presented with HR 180, sweating and SOB
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10
Q

blood pressure is related to

A

BP = CO x SVR

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11
Q

c

cardiac output

A

CO is the volume of blood pumped by the heart per minute and is in turn related to heart rate (HR) and stroke volume (SV) as follows:

CO = HR x SV

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12
Q

stroke volume

A

is the volume of blood pumped by the heart per contraction and is determined by
* Preload
* Myocardial contractility
* Afterload

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13
Q

Preload

A
  • Preload is the ventricular wall tension at the end of diastole and reflects the degree of myocardial muscle fibre stretch; it is determined by volume status, venous capacitance and the difference between mean venous pressure and right atrial pressure
  • Preload is related to SV by the Frank-Starling mechanism; increased fibre length initially leads to an increased SV but above a certain point, the fibres become overstretched and further filling results in a decreased SV, as is the case in cardiac failure
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14
Q

Myocardial contractility

A

is the intrinsic ability of the heart to work independently of preload and afterload; positive inotropes increase the contractility, shifting the Frank-Starling curve upwards

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15
Q

afterload

A

Afterload is the pressure that the heart must work against to eject blood during systole.

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16
Q

why does shock cause lactic acidosis

A
  • Regardless of the cause of shock, inadequate organ perfusion and tissue oxygenation results in cells switching from aerobic to anaerobic metabolism
  • This generates a lactic acidosis that disrupts the cellular environment and causes myocardial depression
17
Q

History in a shocked patient

A

Assessment of severity
* Dyspnoea
* Confusion
* Light-headedness
* Drowsiness
* Oliguria/anuria
Symptoms of the cause

18
Q

approach to shock

A

a to e

Airway

  • May be compromised by reduced conscious level

Breathing

  • Hypoxia
  • Tachypnoea
  • Kussmaul’s breathing: hyperventilation to compensate for metabolic acidosis manifesting as ‘air hunger’

Circulation

  • Cold, pale peripheries
  • Prolonged capillary refill times (CRT >2 s)
  • Tachycardia
  • Hypotension
  • Oliguria
  • Anuria

Disability

  • Confusion
  • Drowsiness
  • Unconsciousness
19
Q

Investigation of shock

A
  • Bloods including blood gas to check pH and lactate
  • Electrocardiogram (ECG)
  • Chest radiograph (CXR)
  • Echocardiography

In trauma
* Pelvic XR
* CT chest/abdo/pelvis as indicated
* FAST

20
Q

initial management of shock

A
  • Assess the patient from an ABCDE perspective
  • Maintain a patent airway
  • Use manoeuvres, adjuncts, supraglottic or definitive airways as indicated and suction any sputum or secretions
  • Deliver high flow oxygen 15L/min via reservoir mask to keep sats over 94%
  • Attach monitoring
  • Pulse oximetry and non-invasive blood pressure
  • Three-lead cardiac monitoring
  • Request 12 lead ECG and portable CXR
  • Obtain large-bore intravenous (IV) access and take bloods including blood gas to check pH and lactate
  • Fluid resuscitation IV
  • Urethral catheterisation and fluid balance monitoring aiming for a urine output >0.5 ml/kg/hour

If BP fails to respond consider referral to HDU/ICU for
* Central line insertion with central venous pressure (CVP) and central venous oxygen saturation (ScvO2) monitoring
* Arterial line insertion and invasive arterial BP monitoring
* Vasopressor and/or inotrope infusion

21
Q

further management of shock: haemorrhagic

A

Identify the source(s) of bleeding and achieve haemorrhage control e.g. direct compression, pelvic binder, splinting of long bone fractures, surgical ligation of bleeding vessels

Restoration of adequate circulating volume:

  • Cross-match blood and activate the major haemorrhage protocol
  • Transfuse O negative blood initially, followed by type-specific and fully cross-matched blood as soon as it is available; aim for permissive hypotension
  • Correct coagulopathy by transfusion of platelets, fresh frozen plasma and cryoprecipitate as appropriate
22
Q

further management: septic shock

A

broad spec antibiotics such as meropenem

23
Q

further management: anaphylactic shock

A

Adrenaline 0.5 mg intramuscular (IM) for anaphylactic shock

24
Q

further management: tension pneumothorax

A

Needle thoracocentesis and intercostal chest drain insertion for tension pneumothorax

25
Q

further management: cardiac tamponade

A

Pericardiocentesis and thoracotomy

26
Q

further management: massive PE

A

Thrombolysis

27
Q

further mangeemnt: unstable tachyarrythmias

A

Synchronised direct current (DC) cardioversion

28
Q

further mangement: unstable bradyarrhythmias

A

pacing