An exploratory investigation of some statistical summaries of oximeter oxygen saturation data from preterm babies

Comparison of 12-hour and 24-hour oximetry recordings in preterm infants

AIM

To compare the overnight 12-hour oximetry component of 24-hour oximetry recordings with the complete 24-h recording in terms of cardiorespiratory status data in preterm infants.

METHODS

Preterm infants from the Wellington neonatal intensive care unit underwent a 24-h pulse oximetry recording immediately prior to discharge home. Each recording was edited to resemble a 12-h overnight recording and compared to the full 24-h recording. Differences in a range of cardiorespiratory variables were assessed as to whether they were statistically significant and, if so, likely to be clinically significant.

RESULTS

The nadirs for heart rate and SpO₂ (both P < 0.001), the time spent <80% SpO₂ (P = 0.017) and highest heart rate (P < 0.001) were significantly different between the two recordings. Only the heart rate nadir differed by more than 5%, suggesting that this may be of clinical significance (median (interquartile range) 54 (28-69) for 24-h recording vs. 78 (54-96) for 12-h recording).

CONCLUSION

The 24-h oximetry reports were clinically similar to 12-h recordings for the majority of variables, and therefore, we suggest that 12-h oximetry studies are sufficient for determining cardiorespiratory status in infants.

24-hour oxygen saturation recordings in preterm infants: editing artefact

AIM

To create editing guidelines for artefact removal in preterm infant pulse oximetry recordings.

METHODS

38 preterm infants ready for discharge home from the neonatal intensive care unit underwent 24-hour pulse oximetry recording using the Masimo^® Rad-8 device. An expert panel determined editing rules based on clinical protocols. For each recording, three reports were generated, 'raw' no editing, 'auto' using the software editing feature and 'manual' reviewed and edited according to the rules. Primary outcome measures were desaturation indices including desaturation index 3% and 4%. Secondary measures included heart rate, mean oxygen saturation and time below 90%.

RESULTS

While all oximetry outcomes differed significantly between editing modes, the majority were not considered likely to influence clinical management. Use of the auto editing compared to no editing did alter by >5%: Time spent <90% oxygen saturation and Desaturation index 4% >10 seconds. The use of manual editing removed extremely low pulse values that were considered unphysiological in this group of otherwise healthy infants.

CONCLUSION

We recommend that oximetry recordings to determine cardiorespiratory stability in newborn infants ready for discharge from the neonatal unit have software editing features applied. This will remove artefact without consuming time in a busy unit.

Predicting 2-y outcome in preterm infants using early multimodal physiological monitoring

BACKGROUND

Preterm infants are at risk of adverse outcome. The aim of this study is to develop a multimodal model, including physiological signals from the first days of life, to predict 2-y outcome in preterm infants.

METHODS

Infants <32 wk gestation had simultaneous multi-channel electroencephalography (EEG), peripheral oxygen saturation (SpO2), and heart rate (HR) monitoring. EEG grades were combined with gestational age (GA) and quantitative features of HR and SpO2 in a logistic regression model to predict outcome. Bayley Scales of Infant Development-III assessed 2-y neurodevelopmental outcome. A clinical course score, grading infants at discharge as high or low morbidity risk, was used to compare performance with the model.

RESULTS

Forty-three infants were included: 27 had good outcomes, 16 had poor outcomes or died. While performance of the model was similar to the clinical course score graded at discharge, with an area under the receiver operator characteristic (AUC) of 0.83 (95% confidence intervals (CI): 0.69-0.95) vs. 0.79 (0.66-0.90) (P = 0.633), the model was able to predict 2-y outcome days after birth.

CONCLUSION

Quantitative analysis of physiological signals, combined with GA and graded EEG, shows potential for predicting mortality or delayed neurodevelopment at 2 y of age.