A new paediatric metabolic monitor.
OBJECTIVE
A paediatric option for the measurement of VO2 and VCO2 (20 to 150 ml/min) has recently been introduced for the adult Deltatrac metabolic monitor (Datex Instrumentarium, Finland) to use in ventilated and spontaneously breathing children. This paper describes a laboratory validation of the paediatric option for ventilated children with regard to the influence of respiratory variables.


METHODS
Respiratory variables were varied within the following ranges: FIO2 0.21-0.8, FIO2-FEO2 (DFO2) 0.01-0.05, FECO2 0.01-0.05, VE 300-6000 ml/min, VT 8-300 ml, RR 10-50/min, P(aw) 10-60 mbar, relative humidity 10% and 60%, and resulted in 107 test situations.


METHODS
Gas exchange was simulated by injection of nitrogen and CO2 at a RQ close to 1.


METHODS
Different situations of paediatric patients ventilated in controlled mode were simulated on a gas injection model.


METHODS
Respiratory and metabolic variables were varied independently to result in a range of 8 to 210 ml/min of VO2 and VCO2.


RESULTS
Reference measurements were carried out by mass spectrometry and wet gas spirometry. The mean VCO2 difference for all tests ranging from 20 ml/min to 210 ml/min was -2.4% (2SD = +/- 12%). The respective VO2 difference was -3.2% (2SD = +/- 23%). Measurement agreement for VO2 in neonatal respirator treatment (20-50 ml/min) compared to older children (50-210 ml/min) showed a mean difference of -3.9% (2SD = +/- 26%) versus -2.8% (2SD = +/- 20%). The respective differences for VCO2 were -7.1% (2SD = +/- 7%) versus +0.4% (2SD = +/- 10%). The mean difference for VO2 as well as VCO2 indicated a high systematic agreement of both methods. The variability (+/- 2SD) in VCO2 measurement is acceptable for all applications. The overall variability in VO2 measurement (2SD = +/- 23%) can be reduced by exclusion of all tests with a FECO2 and DFO2 below 0.03. This results in a mean difference of -3.2% (2SD = +/- 13.7%).


CONCLUSIONS
Within this limitation the paediatric measurement option seems to introduce a valuable method for clinical application in paediatric intensive care medicine.
Weyland
W
W
Department of Anaesthesiology, Emergency and Intensive Care Medicine, University of Göttingen, Germany.
Weyland
A
A
Fritz
U
U
Redecker
K
K
Ensink
F B
FB
Braun
U
U
D002138:Calibration; D002648:Child; D003422:Critical Care / Q000706:statistics & numerical data; D004867:Equipment Design / Q000706:statistics & numerical data; D005069:Evaluation Studies as Topic; D006801:Humans; D007231:Infant, Newborn; D016014:Linear Models; D008961:Models, Structural; D008991:Monitoring, Physiologic / Q000295:instrumentation* / Q000706:statistics & numerical data; D012015:Reference Standards; D012121:Respiration, Artificial