Shock can be classified into 3 different types: Hypovolaemic Shock, Cardiogenic Shock, and Septic Shock. Whilst the management of shock varies based on the type of shock it is, the resulting effect of all 3 types of shock is the same – decreased tissue perfusion.
Distributive Shock
- impaired distribution of circulating blood volume
- vasodilation
- capillary leaks
Distributive Shock is sub-classified into 3 other types of shock: septic shock, anaphylactic shock and neurogenic shock. In this blogpost we will be focusing on Septic Shock.
Septic Shock
While sepsis is defined as a life-threatening organ dysfunction caused by dysregulated host response to infection, a septic shock is defined as a subset of sepsis in which underlying circulatory, cellular and metabolic abnormalities and profound enough to substantially increase the risk of mortality.
- microorganism entry into the patient’s body
- dysregulated host response characterised by excessive peripheral vasodilation, causing maldistribution of blood volume, over-perfused peripheral areas and under-perfused central areas
- is the major cause of admission in the critical care setting
Septic Shock may originate from the community (>80% of cases) or during a stay in a healthcare facility. Common sites for origin of septic shock include:
- lung
- abdomen
- bloodstream
- renal
- gastrointestinal tract
- bone
- soft tissue
- surgical wounds
Infective organisms may include:
- Gram negative bacteria eg. Klebsiella, Escherichia coli, and Pseudomonas aeruginosa
- Gram positive bacteria eg. Staphylococcus aureus and Streptococcus pneumoniae
- Viruses
- Fungi
- Parasites
Predisposing Factors
| Intrinsic Factors | Extrinsic Factors |
| age extremes | invasive devices eg. catheter use |
| malnutrition | immunosuppressing drug therapy eg. steroids |
| co-existing diseases eg. malignancies, AIDS and Diabetes | immunosuppressive therapy eg. chemotherapy |
| wounds | |
| surgical or invasive procedures |
NOTE: all critically ill patients are at an increased risk of developing septic shock.
Septic Shock Signs & Symptoms
- general malaise
- fever OR hypothermia
- tachycardia
- tachypnoea
- altered mental status
- hypotension
- impaired gas exchange
- mottled skin
- prolonged capillary refill
- oliguria – urinary output less than 400 ml per day or less than 20 ml per hour
Investigations
- CBCs
- ABGs
- c-reactive protein
- clotting profile – prothrombin time and INR
- urea & electrolytes
- liver function tests
- urinary function tests
- serum lactate – helps identify cryptic septic shock
Septic Shock Diagnosis
Rapid recognition and resuscitation is crucial for survival, and so, deteriorating patients should be investigated for infection in a timely manner.
| Sepsis | Septic Shock |
| presence of infection | adequate fluid resuscitation not enough |
| acute change in SOFA score of 2 points or more from baseline | vasopressors required to keep MAP at >65mmHg and Serum Lactate at >2mmol/L |
Sequential Organ Failure Assessment Score (SOFA)
SOFA is a bedside tool that helps identify patients with infection at an increased risk of death or prolonged ICU stay. SOFA is considered to be positive when the patient has at least 2 of the following 3 criteria:
- respiratory rate of >22 breaths/minute
- altered mental state with a GCS <15
- systolic blood pressure <100mmHg
Multiple Organ Dysfunction Syndrome (MODS)
MODS refers to a clinical syndrome characterised by acute potentially reversible dysfunction of two or more organs or organ systems not directly involved in the primary disease process. It is the ultimate complication of Septic Shock.
Airway Support
- stabilise the patient’s airway
- maintain oxygen saturation >94% (unless patient has COPD)
- mechanical ventilation may be required to improve oxygenation and neutralise metabolic acidosis
Identifying Source of Sepsis + Treatment
- Microbiology – blood, sputum, CSF, urine, wound swab specimens should be sent immediately for Culture & Sensitivity (2 sets of blood cultures should be taken, the 2nd one being with increased sensitivity for detecting bacteraemia); IMPORTANT: take cultures BEFORE antibiotics are administered (even though broad antibiotics should be started within 1 hour)!
- Radiology – x-ray and CT scan should be performed to check for signs of infection
- IV Antibiotics – start broad spectrum IV antibiotics within one hour to cover likely causative agents such as resistant organisms like MRSA, VREs and Klebsiella, or endogenous infections by colonising bacteria
- Adjust Antibiotic Regime – upon identification of specific pathogens
- Eliminate Sepsis Source within 12 Hours – debride any infected or nectrotic tissue, drain abscesses and secretions, and remove infective invasive devices
Fluid Resuscitation
Fluids are required to counteract absolute hypovolaemia (sweating, diarrhoea, hyperventilation) and relative hypovolaemia (vasodilation and peripheral blood pooling).
- start crystalloids within one hour using the fluid challenge – 30ml/kg over 3 hours, titrating according to response
- if necessary, colloids may be administered to patients who had to receive large volumes of crystalloids
- CAUTION: watch out for fluid and chloride overload
Inotropes and Vasopressors
If fluid administration is unsuccessful in maintaining physiological parameters and adequate perfusion (MAP should be maintained at >65mmHg), or in the case of myocardial dysfunction, inotropes and vasopressors may be required.
- administer noradrenaline to revere inappropriate vasodilation, lower risk of tachycardia and arrhythmias with less adverse metabolic effects
- adrenaline may also be added as an adjunct if required
- dobutamine may also be added if the patient remains unstable; this may also help counteract excessive vasoconstriction, especially within the peripheries
Corticosteroid Use
- corticosteriods (hydrocortisone 200mg/day) may be indicated due to their anti-inflammatory effects in patients unresponsive to fluids and vasopressors NOTE: corticosteroids should not be discontinued abruptly!
Nutrition
- nutritional support is particularly important for patients with septic shock since this helps improve their immune response
- in case of patients with wounds, a high protein diet is recommended since it helps speed up the healing process
- maintain the patient’s blood glucose level at <10mmol/L but avoid excessive glucose control to prevent hypoglycaemia
General Support
- maintain temperature control to decrease metabolic demands
- provide skin care and pressure ulcer prophylactic measures
- provide prophylactic therapy to prevent venous thromboembolism
- prevent over-sedation
- aim to prevent ventilator-acquired pneumonia and infections related to lines/catheter use
- provide blood transfusions only if the patient’s Hgb is <7mmol/L, or in case of bleeding, myocardial ischaemia, and severe hypoxia
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