Shock

1. Seminar: Approach to
Shock
Abdul Waris Khan
4th Year (Medicine)

2. Definition
• Shock is the term used to describe acute circulatory
failure with inadequate or inappropriately
distributed tissue perfusion resulting in generalized
cellular hypoxia and/or an in ability of the cells to
utilize oxygen.

3. Causes of shock
 Abnormalities of tissue perfusion may result from:
 failure of the heart to act as an effective pump
 mechanical impediments to forward flow
 loss of circulatory volume
 abnormalities of the peripheral circulation.

6. CLINICAL FEATURES OF SHOCK
Hypovolaemic shock
 Inadequate tissue perfusion:
(a) Skin – cold, pale, slate-grey, slow capillary refill, ‘clammy’
(b) Kidneys – oliguria, anuria
(c) Brain – drowsiness, confusion and irritability.
 Increased sympathetic tone:
(a) Tachycardia, narrowed pulse pressure, ‘weak’ or ‘thready’ pulse
(b) Sweating
(c) Blood pressure – may be maintained initially (despite up to a 25%
reduction in circulating volume if the patient is young and fit), but
later hypotension supervenes.
 Metabolic acidosis – compensatory tachypnoea.

7. Cardiogenic shock
• Signs of myocardial failure, e.g.
• Raised jugular venous pressure (JVP)
• Pulsus alternans,
• ‘Gallop’ rhythm,
• Basal crackles,
• Pulmonary oedema.

8. Obstructive shock
• Elevated JVP.
• Pulsus paradoxus and muffled heart sounds in
cardiac tamponade.
• Signs of pulmonary embolism

9. Anaphylactic shock
Signs of profound vasodilatation:
(a) Warm peripheries
(b) Low blood pressure
(c) Tachycardia.
■ Erythema, urticaria, pallor, cyanosis.
■ Bronchospasm, rhinitis.
■ Oedema of the face, pharynx and larynx.
■ Hypovolaemia due to capillary leak.
■ Nausea, vomiting, abdominal cramps, diarrhoea.

10. • Sepsis, severe sepsis and septic shock
■ Pyrexia and rigors, or hypothermia (unusual).
■ Nausea, vomiting.
■ Vasodilatation, warm peripheries.
■ Bounding pulse.
■ Rapid capillary refill.
■ Hypotension (septic shock).
■ Occasionally signs of cutaneous vasoconstriction.
■ Other signs:
(a) Jaundice
(b) Coma, stupor
(c) Bleeding due to coagulopathy (e.g. from vascular puncture
sites, GI tract and surgical wounds)
(d) Rash and meningism
(c) Hyper-, and in more severe cases hypoglycaemia

11. Assessment of tissue perfusion
■ Pale, cold skin, delayed capillary refill and the
absence of
visible veins in the hands and feet indicate poor
perfusion.
■ Metabolic acidosis with raised lactate
concentration may suggest that tissue perfusion is
sufficiently compromised to cause cellular hypoxia
and anaerobic glycolysis. dysfunction.
■ Urinary flow is a sensitive indicator of renal perfusion
and haemodynamic performance

13. References
• Kumar & Clark’s Clinical Medicine 7th edition