Pressure Monitoring Definitions
Zeroing
- Zeroing = a process which confirms that atmospheric pressure results in a zero reading by the measurement system
- intermittent confirmation ensures the absence of baseline drift where atmospheric pressure no longer reads zero -> resulting in aberrant results
- this is relatively common with disposable transducers
Levelling (or establishing the zero reference point)
- Levelling = the process which determines the position on the patient you wish to be considered to be zero
- transducers are placed at this point (often utilising fluid filled tubing)
- this is the level of the right atrium (midaxillary line in the supine patient)
- significant errors in measurement may occur if readings using different zero reference points are used (ie. CPP)
Calibration
- Calibration = the process of adjusting the output of a device to match a known input value
- verification of calibration requires the use of a ‘gold standard’ (ie. mercury or water manometer)
- requires a two-step procedure (confirming that zero = zero and 100mmHg = 100mmHg)
- this assesses linearity of the system
- the calibration of disposable transducers is preset and cannot be altered
Example of pressure transducer set-up
Critical Care
Compendium
Chris is an Intensivist and ECMO specialist at the Alfred ICU in Melbourne. He is also a Clinical Adjunct Associate Professor at Monash University. He is a co-founder of the Australia and New Zealand Clinician Educator Network (ANZCEN) and is the Lead for the ANZCEN Clinician Educator Incubator programme. He is on the Board of Directors for the Intensive Care Foundation and is a First Part Examiner for the College of Intensive Care Medicine. He is an internationally recognised Clinician Educator with a passion for helping clinicians learn and for improving the clinical performance of individuals and collectives.
After finishing his medical degree at the University of Auckland, he continued post-graduate training in New Zealand as well as Australia’s Northern Territory, Perth and Melbourne. He has completed fellowship training in both intensive care medicine and emergency medicine, as well as post-graduate training in biochemistry, clinical toxicology, clinical epidemiology, and health professional education.
He is actively involved in in using translational simulation to improve patient care and the design of processes and systems at Alfred Health. He coordinates the Alfred ICU’s education and simulation programmes and runs the unit’s education website, INTENSIVE. He created the ‘Critically Ill Airway’ course and teaches on numerous courses around the world. He is one of the founders of the FOAM movement (Free Open-Access Medical education) and is co-creator of litfl.com, the RAGE podcast, the Resuscitology course, and the SMACC conference.
His one great achievement is being the father of three amazing children.
On Twitter, he is @precordialthump.
| INTENSIVE | RAGE | Resuscitology | SMACC