Shock: diagnosis and treatment updates

2021-06-18 05:05 PM

Distributive shock is caused by excessive vasodilation and impaired blood flow distribution. Septic shock is the most common form of distributive shock and is characterized by significant mortality.

Shock is a medical emergency in which the organs and tissues of the body do not receive adequate blood circulation. This deprives organs and tissues of oxygen and causes the accumulation of toxins. Shock can lead to serious injury or even death.

Aetiology and pathophysiology

Distributive shock is caused by excessive vasodilation and impaired blood flow distribution. Septic shock is the most common form of distributive shock and is characterized by a significant mortality rate (curable, approximately 30%; untreated, possibly >80%).

Other causes of distributive shock include systemic inflammatory response syndrome (SIRS) due to non-infectious inflammatory conditions such as burns and pancreatitis; toxic shock syndrome (TSS); anaphylaxis; reactions to drugs or toxins, including insect bites, blood transfusion reactions, and heavy metal poisoning; acute adrenal insufficiency; liver failure; and neurogenic shock from the brain or spinal cord injury.

Types of shocks

Distributive shock (vasodilation), is a hyperactive process.

Cardiogenic shock (heart failure).

Hypovolemic shock (loss of intravascular volume).

Obstructive shock (physical blockage of blood circulation and insufficient oxygen in the blood).

Systemic inflammatory response syndrome

Temperature is higher than 38°C or lower than 36°C.

Heart rate more than 90 beats per minute.

Respiration over 20 breaths per minute.

Clinical suspicion of systemic inflammatory reaction syndrome is paramount.

Patients in shock are frequently accompanied by tachycardia, tachypnoea, hypotension, altered mental status, and oliguria.

Clinical examination

The main characteristics of distributive shock include the following

Change in mental state.

Heart Rate - More than 90 beats per minute (note that increased heart rate is not apparent if the patient is taking beta-blockers).

Hypotension - Systolic blood pressure less than 90 mm Hg or 40 mm Hg decrease from baseline.

Breathing Rate - More than 20 breaths per minute.

Extremities - Frequent heat, sudden pulse, and increased pulse pressure (systolic minus diastolic pressure) in early shock; Late shock may present as dysfunctional as a vital organ.

Hyperthermia - Core body temperature greater than 38.3°C.

Hypothermia - Temperate core body below 36°C.

Pulse oximetry - Relative hypoxia.

Reduce urine output.

Clinical symptoms of the underlying infections found in distributive shock include 

Pneumonia – Dull percussion, bronchial rales, crackles, bronchial breath sounds

Urinary tract infections - Cornering pain, back pain, dysuria, and polyuria.

Chronic or acute intra-abdominal infection - Localized or diffuse pain on palpation, reduced or absent bowel sounds, recurrent pain.

Soft tissue gangrene or infection - Pain corresponding to lesions, skin discolouration and ulcers, exfoliative rash, necrotic areas under the skin.

Anaphylaxis is characterized by the following clinical symptoms

Respiratory failure.

Wheeze.

Urticaria rash.

Angioedema.

Toxic shock syndrome (TSS) is characterized by the following clinical symptoms

High fever.

A widespread rash with scabs on the palms and soles over the next 1-2 weeks.

Hypotension (possibly orthostatic) and evidence of involvement of 3 other organ systems.

Streptococcal toxic shock syndrome usually presents with localized soft-tissue inflammation and is less commonly associated with a diffuse rash. Sometimes, it can progress explosively within hours.

Adrenal insufficiency is characterized by the following clinical symptoms

Hyperpigmentation of the skin and mucous membranes of the mouth, vagina, and anus may be present

chronic adrenal insufficiency.

Acute or acute-chronic adrenal insufficiency due to physiological stress, hypotension may be the only sign.

Treatment and follow-up

Treatment of the symptom and the cause must be carried out at the same time.

In all cases

Emergency: immediate attention to the patient.

Warm the patient, lay flat, elevate the legs (except in cases of respiratory failure, acute pulmonary oedema).

Insert a peripheral vein with a large cannula (16G in adults). If an intravenous route is not available, use the gastrointestinal route.

Oxygen therapy, ventilatory support in case of respiratory failure.

Assisted ventilation and extracorporeal chest compressions in cardiac arrest.

In-depth monitoring: consciousness, pulse, BP, heart rate, respiratory rate, hourly urine output (urinary catheter) and skin mottling.

Treat according to the cause

Haemorrhage

Control bleeding.

Priority: restore vessel volume as quickly as possible: Insert 2 peripheral intravenous lines.

Ringer Lactate or 0.9% sodium chloride: replace 3 times the estimated loss.

Severe acute dehydration due to bacterial/viral gastroenteritis

Urgently restore volume with intravenous therapy:

Ringer Lactate or Sodium Chloride 0.9%:

Children < 2 months: 10 ml/kg over 15 minutes. Repeat (up to 3 times) if signs of shock persist.

Children 2 - 59 months: 20 ml/kg over 15 minutes. Repeat (up to 3 times) if signs of shock persist.

Children ≥ 5 years and adults: 30 mg/kg over 30 minutes. Repeat once if signs of shock persist.

Then, replace the remaining deficiency with continuous infusion until all signs of dehydration are gone (usually 70 ml/kg over 3 hours).

Closely monitor the patient; Care should be taken to avoid fluid overload in young children and elderly patients).

Note: in severely malnourished children, the rate of intravenous injection is different from that in healthy children.

Serious anaphylactic reaction

Identify the causative agent and eliminate it, e.g. stop the ongoing injection or infusion, but if local, maintain the intravenous route.

Use of epinephrine (adrenaline) intramuscularly, in case of hypotension, swollen throat, or difficulty breathing:

Use undiluted solution (1:1000 = 1 mg/ml) and a 1 ml syringe graduated in 0.01 ml:

Children under 6 years old: 0.15 ml.

Children from 6 to 12 years old: 0.3 ml.

Children over 12 years old and adults: 0.5 ml.

In children, if a 1 ml syringe is not available, use diluent, i.e. add 1 mg of epinephrine to 9 ml of 0.9% sodium chloride to obtain a 0.1 mg/ml solution (1: 10 000):

Children under 6 years old: 1.5 ml.

Children from 6 to 12 years old: 3 ml.

Simultaneously, rapid infusion of Ringer lactate or sodium chloride 0.9%: 1 litre in adults (maximum rate); 20 ml/kg in children, can be repeated if necessary.

If there is no clinical improvement, repeat intramuscular epinephrine every 5 to 15 minutes.

Shock persists after 3 intramuscular, intravenous epinephrine injections at a constant rate using a pump:

Use a diluted solution, i.e. add 1 mg of epinephrine (1:1000) to 9 ml of 0.9% sodium chloride to obtain 0.1mg/ml of a solution (1:10 000):

Children: 0.1 to 1 microgram/kg/minute.

Adults: 0.05 to 0.5 micrograms/kg/min.

Corticosteroids have no effect in the acute phase. However, they must be prescribed when the patient is stable to prevent short-term recurrence:

Hydrocortisone hemisuccinate intramuscular or intravenous

Children: 1 to 5 mg/kg/24 hours in 2 or 3 injections.

Adults: 200 mg, every 4 hours.

In patients with bronchospasm, epinephrine is often effective. If contractions persist, give 10 puffs of inhaled salbutamol.

Septic shock

Replace the intravenous fluid with Ringer Lactate or 0.9% sodium chloride.

Use of vasopressors:

Dopamine IV at a constant rate using a syringe: 10 to 20 micrograms/kg/min or if not administering intravenous epinephrine at a constant rate using a syringe:

Use diluent, i.e. add 1 mg of epinephrine (1:1000) to 9 ml of 0.9% sodium chloride to obtain 0.1 mg/ml of solution (1:10 000). Start with 0.1 microgram/kg/min.

Increase the dose gradually until clinical improvement is observed.

Find the source of the infection (abscess; ENT, pulmonary, gastrointestinal, gynaecological or urinary infections etc.).