Surgery - Shock Flashcards
Define Shock
Acute circulatory failure that compromises tissue perfusion. If untreated will lead to irreversible organ damage and death due to cellular hypoxia
What are the main types of Shock?
Hypovolemic - due to haemmorhage or dehydration
Distributive - due to sepsis, anaphylaxis or neurogenic shock
Cardiogenic shock - direct pump failure
Obstructive shock - indirect pump failure
What are the essential features of Shock?
Fall in BP >40mmHg (SP usually <90mmHg)
Tachycardia (catecholamine release)
Tachypnoea (metabolic acidosis)
What are the specific features of hypovolemic/cardiogenic shock?
Patient is cold, clammy, pale
Rapid, thready pulse
Pulse pressure narrow (vasoconstriction)
What are the specific features of septic shock?
Patient is flushed, hot, sweaty
Rapid, bounding pulse
Pulse pressure wide (vasodilation)
What is the effect of shock on the cerebral system?
Autoregulation over MAP 50-150mmHg Below threshold pt becomes -agitated -confused -drowsy -unresponsive
What is the effect of shock on the cardiac system?
Reduced diastolic pressure –> inadequate myocardial perfusion –> ischaemic chest pain –> arrhythmias –> infarction
What is the effect of shock on the respiratory system?
Increased RR due to metabolic acidosis
What is the effect of shock on the renal system?
Autoregulation over MAP 70-170
Below threshold
-oliguria –> impaired renal funcn
What is the effect of shock on the GI system?
Decreased GI motility/nutrient absorption
Decreased ability to sustain flora –> infection susceptibility
What is the effect of shock on the skin?
Blood supply centralised –> cool/clammy/mottled peripheral skin
What is the main monitoring technique used to help diagnose/manage shock?
Modified Early Warning Score (MEWS)
>3 = urgent medical review
>5 = critical care teams involved
How is cardiac output calculated?
Stroke volume * Heart rate
How is BP calculated?
Cardiac output * Systemic vascular resistance
How is Mean Arterial Pressure calculated?
Diastolic BP + ((systolic/diastolic)/3)
What features suggest Systemic Inflammatory Response Syndrome?
2+ from new: -temp >38.3o OR <36o -RR >20 OR pCO2 <4.3kPa -HR >90bpm -WCC <4 OR >12*10^9 OR -acutely altered mental state OR -glucose >7.7 in a non-diabetic
What is sepsis?
SIRS + a suspected site of infection
What defines severe sepsis?
Sepsis + hypotension OR evidence of end organ dysfunction
- oliguria
- confusion
- lactate >2
- SpO2 <94%
What is septic shock?
Severe sepsis w/ hypotension NOT responding to fludi resus
-results from overactivation of immune system to infective causes
What is the acute management of septic shock?
SEPSIS SIX + SENIOR REVIEW
- O2, 15L/min via non-rebreathe (aim 94%)
- IV fluids, 500ml crystalloid if hypotensive/lactate >2
- IV a/b, according to local guidelines, w/i 1hr
- serum lactate/Hb, blood gas (v/a), senior review if lactate >4
- cultures, prior to a/b if poss, two pairs from separate sites + any indwelling lines + suspected source
- catheterise, keep strict fluid balance
What is anaphylactic shock?
Type IgE mediated hypersensitivity reaction
- mast cells release vasoactive mediators
- cause excessive vasodilation of venous system
- bronchoconstriction & laryngeal oedema
What is the acute management of anaphylactic shock?
Secure airway Remove cause Adrenaline 0.5mg IM (0.5ml 1:1000), repeat every 5mins Chlorphenamine 10mg IV Hydrocortisone 200mg IV Interval bloods for serum tryptase/histamine If wheeze = treat as asthma Raise legs
What is the further management of anaphylactic shock?
ITU admission
ECG monitoring
Epi-pen & skin prick testing
What are the different categories of haemorrhagic shock?
Class I - 750ml, 15% circulating vol, HR <100
Class II - 750-1500ml, 30% circulating vol, HR >100, narrow pulse pressure
Class III - 1500-2000ml, 40% circulating vol, HR >120, hypotensive
Class IV - >2000ml, 40% circulating vol
