Rethinking pathology testing in the ICU - arterial blood gas

Published 3 May 2019. Last updated 9 May 2019.

Rethinking Pathology Testing in the ICU


To understand current ordering practices within the intensive care unit (ICU), specifically:

  • who initiates arterial blood gas (ABG) sampling
  • what are the clinical indications
  • when are these investigations performed
  • how many investigations are performed.

This study will inform a quality improvement project that is operated under the principals of Accelerated Implementation Methodology (AIM) and clinical redesign.

View a poster from the Centre for Healthcare Redesign graduation, May 2019.


To ensure appropriate utilisation of arterial blood gas testing, by reducing the number of tests performed for non-clinical reasons.

The specific aims are:

  • to reduce the total number of tests performed within the Nepean ICU each year from 11,422 to 9137 by July 2019. This equals a 20% reduction based on 2000 admissions to the Nepean ICU in 2017/18 financial year.
  • to reduce the percentage of ABG tests performed for inappropriate non clinical reasons from 29%, as cited in the 2018 Nepean ICU survey data, to 9% by July 2019.


These changes will ensure the following improvement for patients, staff and the health care system as a whole.

Patient experience

  • Reduced pain
  • Reduced risk associated with inappropriate pathology testing that is not clinically indicated
  • Greater autonomy in the ICU when the patient is not attached to an arterial line

Staff experience

  • Better education and greater confidence when deciding if it is appropriate to perform ABG testing, such as being clinically indicated or protocol driven
  • More support in decision-making around ABG testing with a greater role to play in patient care
  • Reduced work and cognitive load

Health care system

  • Ensure sensible, cost-effective use of healthcare resources
  • Reallocation of resources where possible
  • Align more strongly with Choosing Wisely Australia campaign [1]


High frequency, low cost ‘routine’ pathology tests are performed daily as part of the management of critically ill patients in the ICU. It has been suggested that between 30% to 66% of in-hospital pathology tests are unnecessary [1,2,3,4].

The problem with unnecessary pathology testing is the potential for patients to be exposed to the following risks:

  • complications due to sample-collection procedures such as discomfort, haematoma, infection
  • iatrogenic anaemia potentially requiring blood transfusions and their associated risks and complications
  • increased likelihood of false-positive results, over investigation, and adverse outcomes due to unwarranted additional intervention.

There are also additional costs which are more difficult to quantify. These include:

  • nursing hours lost to blood collection
  • medical staff hours associated with reviewing large volumes of pathology results.

In addition to this, financial costs to the public health system are under increasing pressure to ensure sensible and cost-effective use of healthcare resources.

The diagnostic work, performed as part of the initial phase of this project, showed that 29% of all ABG tests performed in the ICU were performed for non clinical reasons. In addition, 70% of all ABG tests are performed when consultants were on call, which means consultants were not on the floor, or within the unit, between 5pm to 8am.

There was also a peak between the number of ABG tests being performed and the nursing staff roster. It showed that ABG tests were performed just before nursing staff hand overs took place.

Overall, this project aims to improve longstanding issues around ABG testing for staff, and more broadly, the healthcare system. Patients are at the centre of this project, with the overarching goal being to improve the patient experience and patient outcomes.


Implementation actions are as follows.

  • Update outdated protocols to reflect what current practices around ABG testing should look like.
  • Develop a clinical pathway regarding ABG testing based on patient acuity for all ICU staff.
  • Put signage in the ICU that covers awareness and provides updates on project progress, targets, success and so forth.
  • Run education sessions and workshops at the start of rotations between junior medical officers and nursing staff, to cover the ‘when where and why’ of ABG testing.
  • Daily discussions to take place, led by consultants on the benefit of ABG tests being performed in past 24 hours.
  • Consultant-led evening ward rounds to take place regarding ABG tests orders for the following day, based on patient level . For example, acuity +/- if a patient requires 1:1 nursing, 2:1 nursing or is cleared for the ward.
  • To create an agreement between consultants, nurse unit managers, clinical nurse unit managers, nurse educators regarding a non-punitive response to errors.
  • Re-program the ABG machine to include the specific clinical reason for ABG testing. This may include deterioration, dialysis, electrolyte disturbance, sepsis and so forth.


Implemented – The project has been implemented and is currently undergoing continual review to determine the level that has been sustained in standard business.


June 2018 to July 2019

Implementation site

This project has been implemented within the Intensive Care Unit at Nepean Hospital (NBMLHD)


Centre for Healthcare Redesign and the Agency for Clinical Innovation Intensive Care NSW Clinical Best Practice Group


  • Post intervention surveys will be conducted to re-examine what the current indications for ABG are, which highlight the effectiveness of interventions around education, protocols and so forth.
  • Audit progress notes will determine if afternoon wards rounds are confirming if ABG tests are to be performed for the following day.
  • Survey junior staff to determine their understanding of ABG tests and when to perform them.
  • Run a monthly review of the total number of ABG tests performed within the unit. This will be compared to the same time in the previous year, prior to any intervention. This data will inform the current key performance indicator of a 20% reduction in total ABG tests performed.

Lessons learnt

  • Quality improvement projects do work!
  • Regardless of how small a project may seem, if a change makes things better for the patient, the staff and the system then it is worth doing!
  • AIM is a useful method that can be applied to small projects.
  • When deciding to explore the benefit of change within a specific area, having the whole team on board from the beginning makes the change more straightforward and sustainable.


  1. NPS MedicineWise. Choose wisely.
  2. Rao GG, Crook M, Tillyer ML. Pathology tests: is the time for demand management ripe at last? J Clin Pathol 2003;56:243-8.
  3. Wong ET, Lincoln TL. Ready, fire! aim! an enquiry into laboratory test ordering. JAMA 1983;250:2510-3.
  4. Peterson SE, Rodin AE. Prudent laboratory usage, cost containment and high quality medical care. Hum Pathol 1987;18:105-8.
  5. Zhi M, Ding EL, Theisen-Toupal J, Whelan J, Arnaout R. The landscape of inappropriate laboratory testing: a 15-year meta-analysis.


Georgina Learmonth
ICU registrar
Nepean Blue Mountains LHD
Phone: 02 4734 4953

Kendall Prendergast
Registered Nurse
Nepean Blue Mountains LHD
Phone: 02 4734 4953


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