The current status of the Automatic Lung Parameter Estimator (ALPE) system.

The current status of the Automatic Lung Parameter Estimator (ALPE) system.

Lars P. Thomsen, Bram W.Smith, Søren Kjærgaard, Per Thorgaard, Egon Toft, Steen Andreassen, Stephen E. Rees

Center for Model-Based Medical Decision Support, Aalborg University, Denmark.

Department of Anasthesiology, Aalborg Hospital, Denmark

The development of the ALPE system

Presented in ESCTAIC 2000, Trieste

Current system.

The principle behind an ALPE measurement

3

Normal person

Patient with oxygenation

problems

The development of the ALPE system

Rees SE, Kjærgaard S, Thorgaard P, Malczynski J, Toft E, Andreassen, S. The Automatic Lung Parameter Estimator (ALPE) system: non-invasive estimation of pulmonary gas exchange parameters in 10-15 minutes. J Clin Monit Comput. 2002 Jan;17(1):43-52.

Clinical studies – Post-operative hypoxaemia

Kjærgaard S et al. Modelling of hypoxaemia after gynaecological laparotomy. Acta Anaesthesiol.Scandi. 2001 Mar;45(3):349-356.

Kjærgaard S et al. Hypoxaemia after cardiac surgery: Clinical application of a model of pulmonary gas exchange. EJA. 2004 Apr;21(4):296-301.

Rasmussen BS et al.  Oxygenation within the first 120 h following coronary artery bypass grafting. Influence of systemic hypothermia (32 degrees C) or normothermia (36 degrees C) during the cardiopulmonary bypass: a randomized clinical trial. Acta Anaesthesiol. Scand. 2006 Jan;50(1):64-71.

Rasmussen BS et al. Oxygenation and release of inflammatory mediators after off-pump compared to after on-pump coronary artery bypass surgery. Acta Anaesthesiologica Scandinavia, 2007, 51(9):1202-10.

Current tools for assesing pulmonary gas exchange.

The Multiple Inert Gas Elimination Technique (MIGET)

MIGET technique• 7 tracer gasses• 45 minutes equilibrium• Gas chromatography analysis

ExperimetalClinicalThe PaO2/FiO2 ratio

• Used in the definition of ALI, ARDS• Very sensitive to changes in FiO2 -

30% of the patients change disease classification.•Poor quantification of gas exchange

• D S Karbing, S Kjaergaard, BW Smith, K Espersen, C Allerod, S Andreassen, SE Rees.  Variation in the PaO2/FiO2 ratio with FiO2: Mathematical and experimental description,

and clinical relevance. Critical Care. 2007;11(6):R118. •Rees SE, Kjaergaard S, Andreassen S, Hedenstierna G. Reproduction of MIGET retention and excretion data using a simple mathematical model of gas exchange in lung damage caused by oleic acid infusion.J Appl Physiol. 2006 Sep;101(3):826-32

• Rees SE, Kjærgaard S, Andreassen S, Hedenstierna G. Reproduction of inert gas and oxygenation data: comparison of the MIGET and a simple model of pulmonary gas exchange.Intensive Care Med. 2010 Aug 6. [Epub ahead of print]

The development of the ALPE system

http://www.mermaidcare.dk/.

The ALPE technology

Gas delivery

The ALPE technology

10

• Demo

12

Conclusions

• The system is now– Portable – no need for gas at the wall.– Usable – little resistance in circuit, and an automated

FiO2 selection procedure.– CE marked as medical product.

• Research future– Looking at incorporating capnography and

transcutaneous CO2.– Evaluation in COPD, comparison with HRCT.