Journal of Clinical Monitoring and Computing
Title: IDENTIFYING THE POSITION OF THE RIGHT ATRIUM TO ALIGN PRESSURE TRANSDUCER FOR CVP. Spirit level or 3D electromagnetic positioning?
Authors: Avellan S1, Uhr I1, McKelvey D2, Sondergaard S3
Affiliation: 1 University of Gothenburg, Medical School, 405 40 Göteborg, Sweden
2 Chalmers University of Technology, Chalmersplatsen 4, 412 96 Gothenburg
3 Department of Anaesthesiology and Intensive Care Medicine, Sahlgrenska University Hospital, Blå Stråket 5,5; 413 45 Gothenburg, University of Gothenburg, Sweden
Corresponding author: Soren Sondergaard,
E-mail: , Telephone: +45 5122 3082, Fax: +45 7841 6407
SURVEY on ACCEPTABLE MEASUREMENT ERROR IN CVP
During spring of 2015 SannaAvellan implemented a project in the postoperative unit. The question was how well the placement of CVP pressure sensor corresponds to the position of the heart. The pressure sensor had been positioned by a spirit level. The position was compared with an electromagnetic determination of the tricuspid valve with internal and external markers.
Statistically, there was no significant difference between the electromagnetic position and location spirit level, but these showed a deviation corresponding to ± 4 mmHg compared with the electromagnetic position.
The concept of “minimal clinically important difference” (MCID) has been introduced to describe the change in an outcome variable, a patient may find clinically significant. For example, a pain management involve a change VAS from 5 to 3 - the change may not be statistically significant, but is highly significant for the patient. MCID, obviously, should be dealt with care and the variable often is ‘anchored’ in validated measurements.
We now want to use the term MCID on the outcome of these studies and anchor this in clinical studies of the correlation between CVP and clinical outcomes.
Thus, Johnson showed a linear relation between pressure in the inferior caval vein (here equated with CVP) and bleeding during liver resection.
What error in measuring the CVP would you accept clinically knowing the relationship shown in the figure?
± 0 mmHg, ± 2 mmHg, ± 4 mmHg, ± 6 mm Hg, ± 8 mmHg or ± 10 mmHg?
Johnson M et al. Correlation between blood loss and inferior vena caval pressure during liver resection. The British Journal of Surgery 1998; 86 (2): 188-190.
Legrand et al. showed an interesting correlation between the Acute Kidney Injury, AKI, and CVP of septic patients, see figure.
Legrand M. et al. Association between systemic hemodynamics and septic acute kidney injury in critically ill patient: a retrospective, observational study. Crit Care 2013; 17: R278
What error in measuring the CVP would you accept clinically knowing the relationship shown in the figure?
± 0 mmHg, ± 2 mmHg, ± 4 mmHg, ± 6 mm Hg, ± 8 mmHg or ± 10 mmHg?