Interactive ABG tool

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Arterial blood gas analysis assessment tool

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• This tool is still under development so please report any issues or feedback to s.kerr@keele.ac.uk• Work through each of the cases to determine the acid-base status of each of the patients. • For each step, select ‘ACCEPT’ to submit your response and receive feedback. • To continue to the next step, select ‘Next step’ to move to the next step in solving the case.

Instructions

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This tool should enable you, the student, to:• interpret ABG results• evaluate acid-base balance disturbances • asssess the most likely cause of the acid-base disturbance & whether there is compensation

Intended Learning Outcomes

(new case)

CASE 5

CASE 4

CASE 3

CASE 2

CASE 1

Introduction

Index

A patient is brought into the casualty department semi-conscious. The patient was found at home with an empty bottle of vodka and an empty bottle of sleeping pills nearby. The patient was not rousable but responded to painful stimuli. Blood gas analysis showed:

Start

Index

Case scenario 1

Back

Next step

First step is to check the oxygenation status of the patient

Step 1.1

Back

Next step

Next step is to determine if there is an acid-base disturbance

Step 1.2

Back

Look at whether there are changes in the PCO2 and HCO3- that could be causing the acid-base disturbance

Next step

Step 1.3

Back

Next step

Think about whether the acid-base disturbance is a change in lung function (PCO2) or is a metabolic change (HCO3-)

Step 1.4

Back

Next step

Use your knowledge of oxygenation and carbon dioxide to determine the answer

Step 1.5

Back

Next step

Check whether the PCO2/HCO3- (the one that wasn't identified as the primary disturbance) has changed in the direction that would help bring the pH back to normal

Step 1.6

Back

Next step

Check the base excess

Step 1.7

Back

Next step

Step 1.8

Case 2

The patient has acute respiratory acidosis due to Type II Respiratory Failure brought on by drug-induced central neural respiratory depression

Case 1 Completed

Congratulations, case solved!

A patient suffered a catastrophic stroke and following this event respiration was seen to be irregular and inadequate (rise in arterial Pco2 recorded). The patient was intubated and ventilated with an inspired oxygen concentration of 40%. Analysis of a blood sample 4 hours later showed:

Start

Index

Case scenario 2

Back

Next step

First step is to check the oxygenation status of the patient

Step 2.1

Back

Next step

Next step is to determine if there is an acid-base disturbance

Step 2.2

Back

Look at whether there are changes in the PCO2 and HCO3- that could be causing the acid-base disturbance

Next step

Step 2.3

Back

Think about whether the acid-base disturbance is a change in lung function (PCO2) or is a metabolic change (HCO3-)

Next step

Step 2.4

Back

Check whether the PCO2/HCO3- (the one that wasn't identified as the primary disturbance) has changed in the direction that would help bring the pH back to normal

Next step

Step 2.5

Back

Check the base excess

Next step

Step 2.6

Back

Next step

Step 2.7

Case 3

The patient has acute respiratory alkalosis brought on by overventilation

Case 2 Completed

Congratulations, case solved!

A patient with abdominal pain due to a duodenal ulcer was admitted to the medical ward with persistent vomiting. He was also taking large quantities of sodium bicarbonate to ease the pain. A sample of arterial blood revealed:

Start

Index

Case scenario 3

Back

Next step

First step is to check the oxygenation status of the patient

Step 3.1

Back

Next step

Next step is to determine if there is an acid-base disturbance

Step 3.2

Back

Look at whether there are changes in the PCO2 and HCO3- that could be causing the acid-base disturbance

Next step

Step 3.3

Back

Think about whether the acid-base disturbance is a change in lung function (PCO2) or is a metabolic change (HCO3-)

Next step

Step 3.4

Back

Check whether the PCO2/HCO3- (the one that wasn't identified as the primary disturbance) has changed in the direction that would help bring the pH back to normal

Next step

Step 3.5

Back

Check the base excess

Next step

Step 3.6

Case 4

The patient has a metabolic alkalosis with respiratory compensation due to consuming large quantities of sodium bicarbonate

Case 3 Completed

Congratulations, case solved!

A 52 year old man was admitted unconscious to casualty. He was a known diabetic on daily insulin. One week ago he had developed a chest infection. He stayed at home and because he stopped eating he stopped his insulin. Over the preceding 2 days he had become increasingly drowsy and in the morning of admission he was unrousable. The arterial blood gas results were:

Start

Index

Case scenario 4

Back

Next step

First step is to check the oxygenation status of the patient

Step 4.1

Back

Next step

Next step is to determine if there is an acid-base disturbance

Step 4.2

Back

Look at whether there are changes in the PCO2 and HCO3- that could be causing the acid-base disturbance

Next step

Step 4.3

Back

Think about whether the acid-base disturbance is a change in lung function (PCO2) or is a metabolic change (HCO3-)

Next step

Step 4.4

Back

Check whether the PCO2/HCO3- (the one that wasn't identified as the primary disturbance) has changed in the direction that would help bring the pH back to normal

Next step

Step 4.5

Back

Check the base excess

Next step

Step 4.6

Case 5

The patient has a metabolic acidosis with respiratory compensation due to diabetic ketoacidosis from not taking his insulin

Case 4 Completed

Congratulations, case solved!

A 48-year-old woman with a history of obesity and sleep apnea presents to the emergency department with complaints of increased shortness of breath, fatigue, and daytime sleepiness over the past week. She reports irregular use of her continuous positive airway pressure (CPAP) machine. The arterial blood gas results were:

Start

Index

Case scenario 5

Back

Next step

First step is to check the oxygenation status of the patient

Step 5.1

Back

Next step

Next step is to determine if there is an acid-base disturbance

Step 5.2

Back

Look at whether there are changes in the PCO2 and HCO3- that could be causing the acid-base disturbance

Next step

Step 5.3

Back

Think about whether the acid-base disturbance is a change in lung function (PCO2) or is a metabolic change (HCO3-)

Next step

Step 5.4

Back

Check whether the PCO2/HCO3- (the one that wasn't identified as the primary disturbance) has changed in the direction that would help bring the pH back to normal

Next step

Step 5.5

Back

Check the base excess

Next step

Step 5.6

Feedback form

The patient has a respiratory acidosis with metabolic compensation due to chronic hypoventilation related to her untreated sleep apnea

Case 5 Completed

Congratulations, case solved!