Shock - Emergency Management

Shock

Clinical Signs

·        CNS: agitation, anxiety, confusion, changed consciousness, convulsions, focal signs, pupillary dilatation 

·        Respiratory - ­RR, ­respiration effort, ­cyanosis, SOB, cough 

·        CVS - ­HR, ¯BP, ¯pulse pressure, ¯capillary return, pallor, sweaty, cool extremities, arrhythmias. Systolic BP < 90 and HR > 100. Treatment should aim to keep BP above 80 mm Hg 

·        Renal - ¯urine output (< 30 ml/hour or < 0.5 ml/kg/hr)

·        Cutaneous: flush, angioedema (selling of face/mouth)

·        GI: abdominal cramps, diarrhoea, vomiting, urinary/faecal incontinence

·        See Topic: Adult Respiratory Distress Syndrome (ARDS)

Septic Shock

·        Systemic Inflammatory Response Syndrome (SIRS) is the presence of 2 or more of:

o   Temp >= 38 C or < 35

o   HR + 90 bpm

o   RR >= 20/min or PaCO2 <= 32 mmHg

o   WBC > 12,000 cells/ml 

·        Septic shock evolves from SIRS when BP <= 90 mmHg despite adequate fluid but need e.g. an inotrope to raise BP 

·        Hyperdynamic circulation: may present early on with warm peripheries because of mediator-induced vasodilation – confusing as they‟re not cold and clammy

·        Infection: 70% due to G –ive: endotoxin release ® inflammatory mediators ® SIRS ® changed haemodynamics 

·        Management:

o  O2 + ventilation

o  Circulatory support

o  Nutrition

o  Treat infection

·        Mortality = 30 – 40 %

Cardiogenic Shock

·        Causes

o  MI or ischaemia: need to lose 40 – 50% of functional ventricular mass

o  Trauma

o  Cardiomyopathy/myocarditis

o  Dysrhythmia

o  Valvular/septal defects

o  Post cardiac surgery: stunned myocardium

o  Drugs 

·        ¯Contractile mass ® ¯CO ® shut down ® hypoxia, ¯LVEDP ® pulmonary oedema (more acute than heart failure) 

·        Management 

o  Maximising coronary perfusion: ¯ afterload, maintain CO (inotropes), vessel patency (drugs, stents, etc), intra-aortic balloon pump 

o  Treat other factors: dysrhythmias, hypertension

o  Support organ failure

Hypovolaemic shock

·        Causes:

o  Blood loss (usually trauma)

o  GI (vomiting, diarrhoea)

o  Renal (diuretics)

o  Surface (burns)

o  Maldistribution (e.g. sepsis, anaphylaxis)

·        Estimated losses from fractures:

o  Femur: 1000 – 1500 mls

o  Pelvis: 1500 – 2500 mls (usually venous)

o  Tibia and fibula: 750 – 1200 mls

o  Humerus: 500 – 750 mls

o  Also chest, abdomen, retroperitoneum, scalp

·        Management: ABC, O2, iv fluids, minimise losses

·        Initial bolus for paediatric shock is 20 ml/kg

Severe Anaphylaxis

·        = Severe allergic reaction

·        See also Topic: Allergy and Hypersensitivity Disorders

·        Problems:

o  Acute CV collapse: hypotension, myocardial ischaemia, arrhythmias 

o  Lower airway: Bronchospasm ® respiratory difficulty. Respiratory problems account for 70% of fatalities. Asthmatics at higher risk. 

o  Upper airway: Laryngeal oedema (ie angioedema)

o  Also skin problems (urticaria, erythema, itch), nausea, vomiting, diarrhoea, anxiety, etc

·        Pathogenesis:

o  Type 1 allergic reactions mediated by IgE antibodies 

o  Previously sensitised ® IgE antibodies against allergen ® mast cell activation ® massive mediator release (histamine, leukotrienes, prostaglandins, kinins) 

o  Histamine leads to: 

§  Smooth muscle contraction ® bronchospasm

§  Vasodilation & ­permeability (can loose 1½ L of blood volume straight away)

§  ­HR and arrhythmias

§  ­Noradrenaline

§  Itch & oedema 

·        Anaphylactoid reaction: activation of mast cells and release of mediators without IgE involvement. Only relevant to investigating cause – not to treatment

·        Examples of allergens: 

o   Drugs: 50% of fatalities. Includes penicillin, muscle relaxants (can be sensitised by exposure to similar drugs), aspirin, contrast media, blood products, streptokinase, preservatives (e.g. in adrenaline) 

o   Foods: 25% of fatalities.  Peanuts, milk, eggs, fish

o   Insect bites: 25% of fatalities

o   Also latex, semen, blood products, physical stimuli (eg exercise, cold, heat)

Presentation

·        Anaesthetics: If IV – then as fast as 1 minute, but normally 5 – 10 minutes.  Food up to 30 minutes

·        1 in 2,500 surgical patients in Wellington.  Death rate 4 – 6 %

Treatment

·        Stop administration of antigen.  Call 777

·        Adrenaline:

o   If no current venous access then 0.5 ml 1:1000 IM.  0.01 mg/kg for kids 

o   If venous access: 0.3 – 0.5 mls iv of 1:1,000 slowly, repeat until BP > 100. Start low (eg 10 mg) and titrate up 

o   Can be nebulised for laryngeal oedema 

o   If on TCAs then ­sensitivity to adrenaline

o   a agonist ® vasoconstriction – but not too much otherwise cardiac vasoconstriction 

o   b agonist ® bronchodilator

o   ­Force of heart contraction

o   ¯Mediator release

o   T½ is short: common error is to give too little too infrequently

·        Also:

o   Metaraminol (a agonist) to stop arrhythmias

o   ?Steroids: prevent late symptoms

o   Promethazine 25 mg slow iv or im (H1 antagonist) + H2 antagonist (e.g. ranitidine), or

o   Antihistamines: Phenergan 25 mg iv slowly for itch

·        If bronchospasm alone: 

o   Salbutamol: 5 – 20 mg/min

o   Hydrocortisone 200 mg iv

o   Aminophylline 5 mg/kg over 30 minutes 

·        Elevate legs ® ­venous return

·        O2 10 l/min by mask: intubate if necessary

·        Wide bore cannula ® 1 – 2 l iv colloid rapidly 

·        If anaesthetic reaction, always investigate so next anaesthetic is safe. Should have skin tests, etc. Cross reactivity between muscle relaxants is not uncommon

Differential Diagnosis

·        Measure serum tryptase (longer T½ than histamine) to confirm anaphylaxis

·        Anaesthetic overdose:  Tryptase raised in anaphylaxis, normal in overdose

·        Respiratory: Pulmonary oedema/embolism, asthma, foreign body

·        Heart: Pericardial tamponade, MI, arrhythmia, vasovagal faint

·        Venous air embolism

·        Septic shock

·        Pneumothorax

·        Transfusion reaction

·        Hypoglycaemia, CVA, epilepsy

Prevention

·        Avoid treatment with b-blockers – makes treatment of anaphylaxis difficult

·        Carry and use adrenaline (eg Epi-pen)

·        Medic alert bracelet

·        Call an ambulance, don‟t „wait and see‟