RT Journal Article
SR Electronic
T1 Non invasive assessment of pulmonary shunt in adults with liver disease
JF European Respiratory Journal
JO Eur Respir J
FD European Respiratory Society
SP p1211
VO 38
IS Suppl 55
A1 Georgia Spentzou
A1 Sunil Sanka
A1 Matt Rutter
A1 Nick Fung
A1 Robert Ross Russell
YR 2011
UL http://erj.ersjournals.com/content/38/Suppl_55/p1211.abstract
AB Introduction: The oxygen dissociation curve charts the relationship between haemoglobin saturation (SaO2) and arterial pO2. Less well known is the relationship between the inspired oxygen (FiO2) and SaO2, which reflects aspects of the oxygen cascade that affect the transfer of oxygen into the blood.A number of models describe this cascade and this allows reconstruction of the curve from a number of data points, allowing estimation of the shunt and whole lung VQ ratio. Its value lies in the simplicity with which both FiO2 and SaO2 can be measured.We are undertaking a “proof of concept” study evaluating shunt in adults undergoing assessment for liver transplantation, where pulmonary shunt is an important clinical problem.Methods: Adults breathe an O2/N2 mix with an FiO2 between 0.14 and 0.35. After equilibration, SaO2 is recorded. At least 3 data points are collected, and analysed using previously validated methodology [1] recently adapted for MATLAB.Results: To date (February 2011) we have studied 9 patients with this technique. All tolerated the procedure well. Studies were performed in our respiratory laboratory and took between 20 and 30 minutes to complete.Shunt varied between 2% and 20% and VQ ratios between 0.78 and 1.5. Patients are also having shunt assessed by VQ scans, and these data will be compared.Conclusions: This technique offers a very simple and well tolerated test that quantifies both shunt and VQ mismatch. It only requires an oximeter and a supply of nitrogen. Given that current methods for assessing these parameters require specialised equipment and are time consuming, it may provide an effective test for shunt or VQ matching in a wide range of patients.Reference:1. Eur J Anaesthesiol 1995:12;375-386.