Arterialised blood gas sampling in the critically ill: Correct tools for the job?

Sampling from blood has been performed for over 200 years. However clinically useful arterial blood gas sampling became a reality after the development of robust methods for measuring oxygen tension from humans in the 1940s. Thus the development of the Clark electrode and subsequent safe tools for sampling plasma, heralded an era of blood sampling, and analysis from which we have not looked back.[1] As with many new medical technologies of their time, it was borne out of a combination of the need for investigational improvements, inventive spirit and serendipity. Arterial Blood gas sampling has been the standard of care for monitoring acid-base disturbance for decades a testimony to its value in diverse settings. Despite this, concerns remain regarding its risks to the patient from repeated same site sampling.[2] This in part led to the alternative approach of arterialized blood samples (AzB), using either an earlobe or Þ nger pulp skin prick.[3] In theory AzB are more easily obtained than ABG, repeatable with better patient tolerance, and accurate. Thus it was surprising to know of the relatively poor uptake of this technique in the ambulatory setting.[4] Despite better utilisation in the UK, ongoing concerns regarding equipment, reliability and accuracy hamper its wider use.[5]