When we attempt to diagnose shock what we are really looking for are signs of failing organs due to inadequate perfusion. In other words, organ dysfunction. We can start this process from the end of the bed.

You can diagnose shock from looking, touching and monitoring the patient.

So, if the patient is alert, has a normal colour, a normal respiratory rate, is warm peripherally, has a normal heart rate and is passing adequate amounts of urine, their oxygen delivery is most probably adequate and shock unlikely. If one or more of these signs are present, then it is safer to assume shock than ignore it.

If suspicious, the next steps would be to observe closely for further deterioration and hunt for more evidence of inadequate perfusion.

An excellent next step investigation would be to perform an arterial blood gas (ABG) looking for a metabolic acidosis (even better if the ABG included a lactate). A metabolic and a lactic acidosis would provide further evidence of organ failure and inadequate oxygenation.

Making a diagnosis early is vital for survival. Identifying the source of sepsis, for example, allow early treatment with appropriate empiric antibiotics or source control (e.g. incision of an abscess, debridement of infected tissues).