Problems in the measurement of functional residual capacity.

Accurate assessment of lung volume in infancy is important to determine the impact of disease and the efficacy of therapies. A new generation of infant plethysmographs with lower apparatus deadspace has been produced, but gives lower volume results than those from older traditional plethysmographs. We hypothesized that the new plethysmographs might have greater sensitivity to the adiabatic effect and hence they, rather than the traditional plethysmographs, produced erroneous results. Our aim was to assess the influence of the adiabatic effect on the results of a contemporary plethysmograph, an older traditional plethysmograph and a helium gas dilution system using a lung model. Altering the amount of copper wool within the lung model allowed the influence of the adiabatic effect on the plethysmographic results to be assessed. The measured compared to the actual volumes were significantly lower for the contemporary plethysmograph compared to the traditional plethysmograph (p < 0.001) and to the helium gas dilution system (p < 0.001). Under optimal testing conditions the contemporary plethysmograph under-recorded by 11-13%, whereas the other two systems gave similar results to the actual volumes. As the effect of the adiabatic effect was increased, the discrepancy between the results of the contemporary and the traditional plethysmographs increased. We conclude, the contemporary plethysmograph is more sensitive to adiabatic effects and hence under-records.

The mortality index for neonatal transportation score: a new mortality prediction model for retrieved neonates.

OBJECTIVE: To develop a mortality prediction score for retrieved neonates based on the information given at the first telephone contact with a retrieval service. METHODS: Data from the New South Wales Newborn and Pediatric Emergency Transport Service database were examined. Analysis was performed with the results for 2504 infants (median gestational age: 36 weeks; range: 24-43 weeks) who were <72 hours of age at the time of referral and whose outcome (neonatal death or survival) was known. The study population was divided randomly into 2 halves, the derivation and validation cohorts. Univariate analysis was performed to identify variables in the derivation cohort related to neonatal death. The variables were entered into a multivariate logistic regression analysis with neonatal death as the outcome. Receiver operator characteristic (ROC) curves were constructed with the regression model and data from the derivation cohort and then the validation cohort. The results were used to generate an integer-based score, the Mortality Index for Neonatal Transportation (MINT) score. ROC curves were constructed to assess the ability of the MINT score to predict perinatal and neonatal death. RESULTS: A 7-variable (Apgar score at 1 minute, birth weight, presence of a congenital anomaly, and infant's age, pH, arterial partial pressure of oxygen, and heart rate at the time of the call) model was constructed that generated areas under ROC curves of 0.82 and 0.83 for the derivation and validation cohorts, respectively. The 7 variables were then used to generate the MINT score, which gave areas under ROC curves of 0.80 for both neonatal and perinatal death. CONCLUSION: Data collected at the first telephone contact by the referring hospital with a regionalized transport service can identify neonates at the greatest risk of dying.

An illness severity score and neonatal mortality in retrieved neonates.

UNLABELLED: The Clinical Risk Index for Babies (CRIB) score is a simple tool to measure clinical risk and illness severity in very low birth weight infants. The aim of this study was to determine if a modified CRIB score (MCRIB) used at first telephone contact with a transport service differentiated between retrieved infants who did or did not die in the neonatal period and hence might be a useful triage tool. A retrospective cohort study of 2504 infants, median gestational age 36 weeks and birth weight 2782 g, transported by the New South Wales Newborn and Paediatric Emergency Transport Service (NETS) was performed. MCRIB was calculated at four time points during the retrieval process. The MCRIB score at the time of the first call and the change in the MCRIB score over the retrieval process were related to outcome (neonatal death or survival). The mean MCRIB score at the time of first call was higher in those infants who died during the neonatal period (4.37) than in those who survived (2.63), (P < 0.0001). MCRIB performed better (area under the receiver operator characteristic curves of 0.72) with regard to predicting mortality than gestational age (0.56) or birth weight (0.52). The mean MCRIB score fell progressively from the time of first call to admission at the accepting NICU (P < 0.0001); infants whose MCRIB score increased were more likely to die (P < 0.0001). CONCLUSION: these results suggest an illness severity score, applied at the time of first call to a transport service would be helpful in setting priorities for retrievals.