Co$t Con$cious Project By Mukti Patel Cohort A

Do we need daily ABGs in all mechanically ventilated patients? Arterial Blood Gas measurement is considered the Gold Standard Test for determining how well your lungs are able to move oxygen into the blood (Oxygenation) and remove carbon dioxide from the blood (Ventilation)

Objectives To identify indications for daily ABGs in intubated patients To assess whether routine ordering of daily ABGs in this population is appropriate To identify cost cutting measures

Advantages Gold standard test for determining the arterial metabolic millieu (pH, PaCO2, HCO3) Can determine PaO2

painful in the awake patient Disadvantages pH, PCO2 (if normocapnic), HCO3 and base excess from a VBG are usually adequate for clinical decision making SpO2 is usually sufficient for clinical decision making unless pulse oximetry is unreliable for other reasons (e.g. shock state) painful in the awake patient increased risk of bleeding and hematoma, infection, nerve injury, digital ischemia Cost: Anywhere from $50 -130

So why then do we get daily ABGs in Intubated Patients?

Many times Serial or daily ABGs are done to monitor and treat issues with oxygenation rather than ventilatory issues For many patients VBG supplemented with pulse oximetry is sufficient means for measuring oxygenation and/or ventilation

ABGs may be indicated in the intubated patient in the following situations to accurately determine PaCO2 in severe shock to accurately determine PaCO2 if hypercapnic (i.e. PaCO2 >45 mmHg) to accurately determine arterial lactate >2mM (rarely necessary)  

ABG vs VBG

Methods Reviewed charts of x number of intubated patients in the ICU Determine whether each of these intubated patients received daily ABGs Of the patients with daily ABGs, determine how many were being monitored for hypercapneic respiratory failure and/or shock

Inclusion/Exclusion Criteria Inclusion criteria: All mechanically ventilated patients in the hospital in the last 1 week regardless of etiology of respiratory failure (shock, hypoxia, hypercarbia, airway monitor) Exclusion Criteria: Non mechanically ventilated patients such as patients on Non invasive respiratory support (Bipap, high flow, NRB, NC)

Results Patient Daily ABG? Hypercapneic Respiratory Failure? (PCO2>45 Shock? Severe Acidosis? (pH<7.1) Could use VBG instead/No hypoxia? 1. Yes No 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. Of the 15 intubated patients, Daily ABGs were ordered on 11 of these patients and were not ordered on 4. Of those 11 patients, Only 4 patients truly required ABGs in order to monitor respiratory status. Of the 15 intubated patients, VBGs could have been used in 10 of these patients. Of these 10 patients, VBGs were used in place of ABGs in 3 of these patients.

Results Of the 15 intubated patients, Daily ABGs were ordered on 11 of these patients and were not ordered on 4. Of those 11 patients, Only 4 patients truly required ABGs in order to monitor respiratory status. Of the 15 intubated patients, VBGs could have been used in 10 of these patients. Of these 10 patients, VBGs were used in place of ABGs in 3 of these patients.

Learning Points ABGs are not indicated in every intubated patient It’s important to identify what aspect of respiratory function you are trying to measure, monitor or modify It’s also important to understand when alternative measures, apart from ABG can be used to measure, monitor or modify said aspect of respiratory function.