121 VALIDATION OF A HOT WIRE ANENCMETER IN OBTAINING RESPIRATORY SYSTEM COMPLIANCE IN INTUBATED INFANTS

We validated the use of hot wire anenometry (NVM Bear Corp) to derive respiratory complicance in intubated infants, against the gold standard (GS) of single breath occlusion values in the same infants. Tidal flow was measured by hot wire anenometry; enabling an integral volume to be obtained. The quotient of volume and the inflation pressure amplitude of the ventilator provided respiratory system compliance. To ensure fully passive expiration, only paralysed or sedated patients were studied. Analyses were blinded to results of the alternate method. 15 RDS infants were recruited (BW 4.4±0.9 kg). Of these 12 infants were amenable to analysis. Three were excluded as the single breath analysis to proved technically impossible. By anenometer compliance range was: 0.21-1.78 ml/cm H2O; by the GS: 0.24-1.88 ml/cm H2O). Agreement between the two methods was excellent. Inspired volume: correlation coefficient: 0.989. Expired volume: correlation coefficient 0.991. We conclude that the Neonatal Volume Monitor can be used to obtain valid estimates of respiratory compliance on-line in intubated infants. Further, in those infants where single breath values cannot be obtained, the NVM provides an estimate of compliance.