Shock

Acute circulatory failure leading to inadequate tissue perfusion which, if prolonged, results in irreversible organ failure. Mortality is high without early diagnosis and treatment.

Aetiology and pathophysiology

Hypovolaemic shock

Absolute hypovolaemia due to significant intravascular fluid depletion:
– Internal or external haemorrhage: post-traumatic, peri or postoperative, obstetrical (ectopic pregnancy, uterine rupture, etc.), blood loss due to an underlying condition (gastrointestinal ulcer, etc.). A loss of greater than 30% of blood volume in adults will lead to haemorrhagic shock.
– Dehydration: severe diarrhoea and vomiting, intestinal obstruction, diabetic ketoacidosis or hyperosmolar coma, etc.
– Plasma leaks: extensive burns, crushed limbs, etc.

Relative hypovolaemia due to vasodilation without concomitant increase in intravascular volume:
– Anaphylactic reaction: allergic reaction to insect bites or stings; drugs, mainly neuromuscular blockers, antibiotics, acetylsalicylic acid, colloid solutions (dextran, modified gelatin fluid); equine sera; vaccines containing egg protein; food, etc.
– Acute haemolysis: severe malaria, drug poisoning (rare).

Septic shock

By a complex mechanism, often including vasodilation, heart failure and absolute hypovolaemia.

Cardiogenic shock

By decrease of cardiac output:
– Direct injury to the myocardium: infarction, contusion, trauma, poisoning.
– Indirect mechanism: arrhythmia, constrictive pericarditis, haemopericardium, pulmonary embolism, tension pneumothorax, valvular disease, severe anaemia, beri beri, etc.
 

Clinical features

Signs common to most forms of shock

– Pallor, mottled skin, cold extremities, sweating and thirst.
– Rapid and weak pulse often only detected on major arteries (femoral or carotid).
– Low blood pressure (BP), narrow pulse pressure, BP sometimes undetectable.
– Capillary refill time (CRT) > 3 seconds.
– Cyanosis, dyspnoea, tachypnoea are often present in varying degrees depending on the mechanism.
– Consciousness usually maintained (more rapidly altered in children), but anxiety, confusion, agitation or apathy are common.
– Oliguria or anuria.

Signs specific to the mechanism of shock

Hypovolaemic shock

The common signs of shock listed above are typical of hypovolaemic shock.
Do not underestimate hypovolaemia. Signs of shock may not become evident until a 50% loss of blood volume in adults.

Anaphylactic shock

– Significant and sudden drop in BP
– Tachycardia
– Frequent cutaneous signs: rash, urticaria, angioedema
– Respiratory signs: dyspnoea, bronchospasm

Septic shock

– High feveror hypothermia (< 36 °C), rigors, confusion
– BP may be initially maintained, but rapidly, same pattern as for hypovolaemic shock.

Cardiogenic shock

– Respiratory signs of left ventricular failure (acute pulmonary oedema) are dominant: tachypnoea, crepitations on auscultation.
– Signs of right ventricular failure: raised jugular venous pressure, hepatojugular reflux, sometimes alone, more often associated with signs of left ventricular failure.

The aetiological diagnosis is oriented by:
– The context: trauma, insect bite, ongoing medical treatment, etc.
– The clinical examination:
• fever
• skin pinch consistent with dehydration
• thoracic pain from a myocardial infarction or pulmonary embolus
• abdominal pain or rigidity of the abdominal wall from peritonitis, abdominal distension from intestinal obstruction
• blood in stools, vomiting blood in intestinal haemorrhage
• subcutaneous crepitations, likely anaerobic infection
 

Management

Symptomatic and aetiological treatment must take place simultaneously.

In all cases

– Emergency: immediate attention to the patient.
– Warm the patient, lay him flat, elevate legs (except in respiratory distress, acute pulmonary oedema).
– Insert a peripheral IV line using a large calibre catheter (16G in adults). If no IV access, use intraosseous route.
– Oxygen therapy, assisted ventilation in the event of respiratory distress.
– Assisted ventilation and external cardiac compression in the event of cardiac arrest.
– Intensive monitoring: consciousness, heart rate, BP, CRT, respiratory rate, hourly urinary output (insert a urinary catheter) and skin mottling.

Management according to the cause

Haemorrhage

– Control bleeding (compression, tourniquet, surgical haemostasis).Réa
– Determine blood group.
– Priority: restore vascular volume as quickly as possible: 

Insert 2 peripheral IV lines (2 catheters 16G in adults).
Ringer lactate or 0.9% sodium chloride: replace 3 times the estimated losses
and/or plasma substitute: replace 1.5 times the estimated losses

– Transfuse: classically once estimated blood loss represents approximately 30 to 40% of blood volume (25% in children). The blood must be tested (HIV, hepatitis B and C, syphilis, malaria in endemic areas, etc.) 

Severe acute dehydration due to bacterial/viral gastroenteritis

– Urgently restore circulating volume using IV therapy with Ringer lactate or 0.9% sodium chloride. See Chapter 3, Acute diarrhoea.

– Closely monitor the patient; be careful to avoid fluid overload in young children and elderly patients).

Note: in severely malnourished children the IV rate is different than those for healthy children (see Severe acute malnutrition).

Severe anaphylactic reaction

– Determine the causal agent and remove it, e.g. stop ongoing injections or infusions, but if in place, maintain the IV line.

– Administer epinephrine (adrenaline) IM, into the antero-lateral tight, in the event of hypotension, pharyngolaryngeal oedema, or breathing difficulties:

Use undiluted solution (1:1000 = 1 mg/ml) and a 1 ml syringe graduated in 0.01 ml:
Children under 6 years: 0.15 ml
Children from 6 to 12 years: 0.3 ml
Children over 12 years and adults: 0.5 ml

In children, if 1 ml syringe is not available, use a diluted solution, i.e. add 1 mg epinephrine to 9 ml of 0.9% sodium chloride to obtain a 0.1 mg/ml solution (1:10 000):
Children under 6 years: 1.5 ml
Children from 6 to 12 years: 3 ml

At the same time, administer rapidly Ringer lactate or 0.9% sodium chloride: 1 litre in adults (maximum rate); 20 ml/kg in children, to be repeated if necessary.
If there is no clinical improvement, repeat IM epinephrine every 5 to 15 minutes.

In shock persists after 3 IM injections, administration of IV epinephrine at a constant rate by a syringe pump is necessary:
Use a diluted solution, i.e. add 1 mg epinephrine (1:1000) to 9 ml of 0.9% sodium chloride to obtain a 0.1 mg/ml solution (1:10 000):
Children: 0.1 to 1 microgram/kg/minute
Adults: 0.05 to 0.5 microgram/kg/minute
If syringe pump is not available, see box.

– In patients with bronchospasm, epinephrine is usually effective. If the spasm persists give 10 puffs of inhaled salbutamol.

Note: corticosteroids are not indicated in the initial treatment of anaphylaxis. They may be administered once the patient is stabilised to prevent recurrence in the short term (prednisolone PO: 0.5 to 1 mg/kg once daily for 1 to 2 days).

Septic shock

– Vascular fluid replacement with Ringer Lactate or 0.9% sodium chloride or plasma substitute.

– Use of vasoconstrictors:

dopamine IV at a constant rate by syringe pump (see box): 10 to 20 micrograms/kg/minute
or, if not available
epinephrine IV at a constant rate by syringe pump:
Use a diluted solution, i.e. add 1 mg epinephrine (1:1000) to 9 ml of 0.9% sodium chloride to obtain a 0.1 mg/ml solution (1:10 000). Start with 0.1 microgram/kg/minute. Increase the dose progressively until a clinical improvement is seen.
If syringe pump is not available, see box.

– Look for the origin of the infection (abscess; ENT, pulmonary, digestive, gynaecological or urological infection etc.). Antibiotic therapy according to the origin of infection:

Origin

Antibiotic therapy

Alternative

Cutaneous
staphylococci, streptococci


cloxacillin + gentamicin


Pulmonary
pneumococci, Haemophilus influenzae


ampicillin or ceftriaxone
+/- gentamicin


co-amoxiclav or ceftriaxone
+ ciprofloxacin

Intestinal or biliary
enterobacteria, anaerobic bacteria, enterococci


co-amoxiclav + gentamicin


ceftriaxone + gentamicin
+ metronidazole

Gynaecological
streptococci, gonococci, anaerobic bacteria, E. coli


co-amoxiclav + gentamicin


ceftriaxone + gentamicin
+ metronidazole

Urinary
enterobacteria, enterococci


ampicillin + gentamicin


ceftriaxone + ciprofloxacin

Other or undetermined

ampicillin + gentamicin

ceftriaxone + ciprofloxacin

ampicillin IV
Children over 1 month: 50 mg/kg every 6 to 8 hours 

Adults: 1 to 2 g every 6 to 8 hours

cloxacillin IV infusion (60 minutes)
Children over 1 month: 50 mg/kg every 6 hours (max. 8 g daily)
Adults: 3 g every 6 hours

amoxicillin/clavulanic acid (co-amoxiclav) slow IV injection (3 minutes) or IV infusion (30 minutes)
Doses are expressed in amoxicillin:
Children less than 3 months: 50 mg/kg every 12 hours
Children ≥ 3 months and < 40 kg: 50 mg/kg every 8 hours (max. 6 g daily)
Children 40 kg and adults: 2 g every 8 hours

ceftriaxone slow IV (3 minutes) 1
Children: 100 mg/kg once daily
Adults: 2 g once daily

ciprofloxacin PO (by nasogastric tube)
Children: 15 mg/kg 2 times daily
Adults: 500 mg 2 times daily

gentamicin IM or slow IV (3 minutes) 
Children ≥ 1 month and adults: 6 mg/kg once daily

metronidazole IV infusion (30 minutes)
Children over 1 month: 10 mg/kg every 8 hours (max. 1500 mg daily)
Adults: 500 mg every 8 hours

– Corticosteroids: not recommended, the adverse effects outweigh the benefits.

Cardiogenic shock

The objective is to restore efficient cardiac output. The treatment of cardiogenic shock depends on its mechanism.

– Acute left heart failure with pulmonary oedema

Acute pulmonary oedema (for treatment, see Heart failure in adults, Chapter 12).

In the event of worsening signs with vascular collapse, use a strong inotrope:
dopamine IV at a constant rate by syringe pump (see box): 3 to 10 micrograms/kg/minute

Once the haemodynamic situation allows (normal BP, reduction in the signs of peripheral circulatory failure), nitrates or morphine may be cautiously introduced.

Digoxin should no longer be used for cardiogenic shock, except in the rare cases when a supraventricular tachycardia has been diagnosed by ECG. Correct hypoxia before using digoxin.
digoxin slow IV
Children: one injection of 0.010 mg/kg (10 micrograms/kg), to be repeated up to 4 times per 24 hours if necessary

Adults: one injection of 0.25 to 0.5 mg, then 0.25 mg 3 or 4 times per 24 hours if necessary

– Cardiac tamponade: restricted cardiac filling as a result of haemopericardium or pericarditis.
Requires immediate pericardial tap after restoration of circulating volume.

– Tension pneumothorax: drainage of the pneumothorax.

– Symptomatic pulmonary embolism: treat with an anticoagulant in a hospital setting.


Administration of dopamine or epinephrine at a constant rate requires the following conditions:
– close medical supervision in a hospital setting;
– use of a dedicated vein (no other infusion/injection in this vein), avoid the antecubital fossa if possible;
– use of an electric syringe pump (or infusion pump);
– progressive increase and adaptation of doses according to clinical response;
– intensive monitoring of drug administration, particularly during syringe changes.

Example:
dopamine: 10 micrograms/kg/minute in a patient weighing 60 kg
Hourly dose: 10 (micrograms) x 60 (kg) x 60 (min) = 36 000 micrograms/hour = 36 mg/hour
In a 50 ml syringe, dilute one 200 mg-ampoule of dopamine with 0.9% sodium chloride to obtain 50 ml of solution containing 4 mg of dopamine per ml.
For a dose of 36 mg/hour, administer the solution (4 mg/ml) at 9 ml/hour.

If there is no electric syringe pump, dilution in an infusion bag may be considered. However, it is important to consider the risks related to this type of administration (accidental bolus or insufficient dose). The infusion must be constantly monitored to prevent any, even small, change from the prescribed rate of administration.

Example for epinephrine:

– In adults:

Dilute 10 ampoules of 1 mg epinephrine (10 000 micrograms) in 1 litre of 5% glucose or 0.9% sodium chloride to obtain a solution containing 10 micrograms of epinephrine per ml.
Knowing that 1 ml = 20 drops, in an adult weighting 50 kg:
• 0.1 microgram/kg/minute = 5 micrograms/minute = 10 drops/minute
• 1 microgram/kg/minute = 50 micrograms/minute = 100 drops/minute, etc.

– In children:

Dilute 1 ampoule of 1 mg epinephrine (1000 micrograms) in 100 ml of 5% glucose or 0.9% sodium chloride to obtain a solution containing 10 micrograms of epinephrine per ml.
For administration, use a paediatric infusion set; knowing that 1 ml = 60 drops, in a child weighting 10 kg:
• 0.1 microgram/kg/minute = 1 microgram/minute = 6 drops/minute
• 0.2 microgram/kg/minute = 2 micrograms/minute = 12 drops/minute, etc.


Note
: account for all infused volumes when recording ins and outs.


Footnotes
Ref Notes
1

 The solvent of ceftriaxone for IM injection contains lidocaine. Ceftriaxone reconstituted using this solvent must never be administered by IV route. For IV administration, water for injection must always be used.