Shock Flashcards by Alaa M.

When does shock occur?

When there is insufficient tissue perfusion

How well did you know this?

Not at all

Perfectly

What is septic shock?

Infection that triggers a particular Systemic Inflammatory Response Syndrome (SIRS)

How well did you know this?

Not at all

Perfectly

Characteristics of septic shock

Body temperature outside 36 oC - 38 o C
HR >90 beats/min
Respiratory rate >20/min
WBC count >12,000/mm3 or < 4,000/mm3

How well did you know this?

Not at all

Perfectly

Patients with infections and ______ elements of SIRS meet the diagnostic criteria for sepsis

2 ore more elements

How well did you know this?

Not at all

Perfectly

Those with organ failure have severe sepsis and those with refractory hypotension have..

Septic shock

How well did you know this?

Not at all

Perfectly

The overall hallmarks of septic shock are..

Excessive inflammation, coagulation and fibrinolytic suppression

How well did you know this?

Not at all

Perfectly

Key areas for attention in septic shock

Prompt administration of antibiotics
Haemodynamic stabilisation
Modulation of the septic response

How well did you know this?

Not at all

Perfectly

In surgical patients, the main groups with septic shock include..

Anastomotic leaks, abscesses and extensive superficial infections such as necrotising fasciitis

How well did you know this?

Not at all

Perfectly

The average adult blood volume comprises 7% of body weight. Thus in the 70 Kg adult this will equate to..

5 litres

How well did you know this?

Not at all

Perfectly

T or F: Average adult blood volume changes in children and is slightly lower in the elderly

True

How well did you know this?

Not at all

Perfectly

Blood loss of <750ml is classed as class __ of haemorrhagic shock

One

How well did you know this?

Not at all

Perfectly

Blood loss of 750-1500ml is classed as class __ of haemorrhagic shock

Two

How well did you know this?

Not at all

Perfectly

Blood loss of 1500-2000ml is classed as class __ of haemorrhagic shock

Three

How well did you know this?

Not at all

Perfectly

Blood loss of >2000ml is classed as class __ of haemorrhagic shock

Four

How well did you know this?

Not at all

Perfectly

The main groups with haemorrhagic shock include..

Trauma
Tension pneumothorax
Spinal cord injury
Myocardial contusion
Cardiac tamponade

How well did you know this?

Not at all

Perfectly

When assessing trauma patients it is worth remembering that in order to generate a palpable femoral pulse an arterial pressure of _________ is required

> 65mmHg

How well did you know this?

Not at all

Perfectly

Once bleeding is controlled and circulating volume normalised the levels of transfusion should be to maintain a Hb of _______ in those with no risk factors for tissue hypoxia and Hb of _____ for those who have such risk factors

Once bleeding is controlled and circulating volume normalised the levels of transfusion should be to maintain a Hb of 7-8 in those with no risk factors for tissue hypoxia and Hb 10 for those who have such risk factors.

How well did you know this?

Not at all

Perfectly

Neurogenic shock often occurs following a..

Spinal cord transection (usually at a high level)

How well did you know this?

Not at all

Perfectly

Neurogenic shock results in..

Decreased sympathetic tone or increased parasympathetic tone

How well did you know this?

Not at all

Perfectly

How does neurogenic shock relate to Starling’s law?

There is a decrease in peripheral vascular resistance mediated by marked vasodilation. This results in decreased preload and thus decreased cardiac output. There is decreased peripheral tissue perfusion and shock is thus produced

How well did you know this?

Not at all

Perfectly

In neurogenic shock, peripheral vasodilators/ vasoconstrictors are used to return vascular tone to normal

Vasoconstrictors

How well did you know this?

Not at all

Perfectly

In medical patients, the main cause of cardiogenic shock is..

Ischaemic heart disease

In the traumatic setting, the main cause of cardiogenic shock is..

Direct myocardial trauma or contusion

In cardiogenic shock, evidence of ECG changes and overlying sternal fractures or contusions should raise the suspicion of..

Injury

In cardiogenic shock, ________________ should be used to determine evidence of pericardial fluid or direct myocardial injury

Transthoracic echocardiography

When cardiac injury is of a blunt nature and is associated with cardiogenic shock the right/left side of the heart is the most likely site of injury with chamber and or valve rupture

Right

Surgial Tx for right side injury/chamber or valve rupture in cardiogenic shock

Cardiopulmonary bypass Some may require intra-aortic balloon pump as a bridge to surgery

Life-threatening, generalised or systemic hypersensitivity reaction

Anaphylactic shock

Most important drug in anaphylactic shock?

Adrenaline - can be repeated every 5 minutes if necessary

The best site for IM injection is the..

Anterolateral aspect of the middle third of the thigh

Common identified causes of anaphylaxis

Food (e.g. Nuts) - the most common cause in children Drugs venom (e.g. Wasp sting)

What three things does normal tissue perfusion rely on?

Cardiac Function Capacity of vascular bed Circulating blood volume

Surrogate markers for normal perfusion

Blood pressure Consciousness (Brain perfusion) Urine output (Renal perfusion) Lactate (General tissue perfusion)

What is Hypovolaemic shock?

Acute haemorrhage - “Fluid deplete” states Severe dehydration, burns

Physiology of Hypovolaemic shock?

Volume depletion – leading to reduced SVR Reduced volume returning to heart – reduced pre-load and hence reduced CO

In cardiogenic shock, if due to MI, suggests that >40% of ___ is involved

Examples of obstructive shock

Direct obstruction to cardiac output (PE, Air/Fat/Amniotic fluid-embolism) Restriction of cardiac filling (Tamponade, Tension pneumothorax)

Examples of Distributive shock

Septic, anaphylaxis, acute liver failure, spinal cord injuries

Physiology of distributive shock

Due to disruption of normal vascular autoregulation, and profound vasodilatation. Poor perfusion – despite increased cardiac output

What is Endocrine shock?

Severe uncorrected hypothyroidism, Addisonian crisis – both reduced CO and vasodilation

Most common cause of shock

Distributive (septic)

What does the neuroendocrine response release?

Pituitary hormones – adrenocorticotrophic hormone, anti-diuretic hormone, endogenous opioids Cortisol – fluid retention, antagonises insulin Glucagon

The inflammatory response is often followed by secondary..

Immune suppression, leaving predisposition to secondary infection

Function of nitric oxide?

Regulation of blood flow, coagulation, neural activity and immune function

Where is nitric oxide produced?

Produced in minute (picomolar) concentrations in endothelial and other cells by cNOS

T or F: Inflammation pathways activiate nitric oxide's inducible isoform iNOS in vessel smooth walls leading to 1000 fold increase in NO production

True

Haemodynamic changes

Gold standard for monitoring cardiac output

Thermodilution with a PA catheter – rarely used outside specialist units

Fluid challenge

300-500ml over 10-20 mins

Fluid choices

Crystalloids - need significantly larger volumes Colloids - can cause anaphylaxis Blood - will stay in circulation but scarce and has multiple risks

Drugs used if fluid management does not work

Adrenaline (Epinephrine) Noradrenaline (Norepinephrine) Vasopressin (ADH) Dopamine Dobutamine/Dopexamin

Next step if both fluids and drugs don't work

Mechanical support options * In cardiogenic shock: balloon pumps, L-VADs,R-VADs * In severe cases – VA-ECMO

Consequences of resuscitation

Volume delivered never remains intra-vascular Extra-vascular overload, in an intra-vascularly “dry” patient Sub-cutaneous oedema obvious Less obvious – “wet” lungs/ARDS, bowel oedema

De-Escalation / “De-Resucitation”

Spontaneous, Diuretic, Dialysis