Interpretation of ELCBG – ICST

Interpretation of ELCBG

The aim of this National Welsh Standard is to break down the uncertainty surrounding ELCBG interpretation.

Check out the tutorials on the interpretation of ELCBG, before completing the assessment to achieve the certificate against the National Welsh Standard (NWS).


Normal Values

pH Normal Range

PaO2 Normal Range

PaCO2 Normal Range

HCO3 Normal Range

Base Excess Normal Range

SaO2 Normal Range

SpO2 Normal Range

Fractional Inspired Oxygen Concentration

The patient’s clinical context

Is the pH normal?

Compensatory mechanisms for acid-base imbalance

Respiratory and Metabolic Acidosis and Alkalosis

Respiratory abnormalities

Type I Respiratory Failure

Type II Respiratory Failure

Respiratory Acidosis

Respiratory Alkalosis

Metabolic Abnormalities

Metabolic Acidosis

Metabolic Alkalosis

Advanced Interpretation Algorithm (branch 1)

Advanced Interpretation Algorithm (branch 2)

Advanced Interpretation Algorithm (branch 3)

Oxygen partial pressure, saturation of haemoglobin and inspired oxygen

Case study 1

Case study 2

Case study 3

Case study 4

Case study 5

Case study 6

Case study 7

Case study 8

Case study 9

Case study 10


All Wales Blood Gas Sampling Guideline – Capillary and Arterial


Interpretation of ELCBG

This NWS is awarded on completion of a 15-question, 25-minute case-based assessment. The purpose of the assessment is to emulate the clinical scenario and to assess practitioners’ decision-making skills against the expectations of the national Respiratory Health Implementation, according to the national standards for Wales.

If this is your first time working through an Assessment in a National Welsh Standard, Welcome! This section includes instructions on complete the Assessment.

The MCQ has 15 questions and you have 25 minutes to complete it.

To achieve a certificate you must answer 12 or more questions correctly (a pass mark of 80%). You can retake the assessment as many times as you need. Your certificate will appear here, in the overview tab.

The education and resources tabs provide relevant learning materials to help you prepare for the assessment.

When you are ready to do the assessment, select the assessment tab and follow the instructions.

Undertake Assessment

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