Relationship Between Perfusion Index and Snappe-ii Scores in Neonates Admitted to Kenyatta National Hospital Newborn Unit

Abstract

Background: Neonatal morbidity and mortality remain of worldwide concern, especially in low- and middle-income countries. Early recognition of severe neonatal illness guides the intensity of therapy. This currently employs several validated scoring systems amongst which the SNAPPE-II score has found the most utility. There is however, a continued need for quick and efficient methods in assessing disease severity amongst neonates. Pulse oximetry offers promise in this regard using the perfusion index as a marker of tissue perfusion. Perfusion index is the ratio of pulsatile blood flow to non-pulsatile blood flow in peripheral tissue and is expressed as a percentage. Establishing clarity in the relationship between PI and SNAPPE II could provide a guide to the potential expanded utilization of perfusion index in the assessment of neonatal disease severity. Study question: What is the relationship between the perfusion index and SNAPPE-II score in neonates admitted to Kenyatta National Hospital NBU? Broad objective: To investigate the relationship between the perfusion index and SNAPPE-II score in neonates admitted to Kenyatta National Hospital NBU. Methodology: The study was a descriptive cross-sectional study at Kenyatta National Hospital, Newborn Unit. The study population involved neonates admitted to KNH NBU. The study duration was 6 months and consecutive sampling was used to enroll neonates into the study. A total of 139 neonates completed the study. The SNAPPE-II scores of eligible neonates were recorded within 24 hours of admission. The perfusion index was recorded within 24 h of admission using a Masimo SET Radical-7 pulse oximeter. Data handling and analysis: Data were cleaned, coded, and entered into R studio and Microsoft excel. Relevant descriptive statistics were used to summarize the data. Correlation between PI and SNAPPE-II score was assessed using Pearson’s correlation. A p-value <0.05 was considered statistically significant. Linear regression of the relationship between PI and SNAPPE II scores was done to derive an equation describing the relationship. Receiver operating curves were plotted and the area under the curve was calculated to determine the predictive value of the PI on disease severity. Results are presented using frequency tables and graphs. xiii Ethics and related procedures: Ethical approval was obtained from the KNH-UON ethics and review committee (KNH-UoN ERC). Permission was also obtained from the KNH administration before the commencement of the study. Results: A total of 139 neonates completed the study. Out of these, 79 were term infants(57%) and 60 were preterm infants(43%), with female infants accounting for 51.8% and male infants 48.2%. The mean gestational age was 35.9±4.0 weeks with a mean birth weight of 2434.3±865.8 grams. The median SNAPPE II score was 32 with an interquartile range of 16-56. The mean perfusion index was 0.90±0.14 SD. Pearson's correlation coefficient, R, between mean PI and SNAPPE II scores was -0.56 (p<0.0001). The PI cut-off values generated were ≥0.88 for mild disease (AUC=0.91) and PI<0.83 for severe disease (AUC=0.74). Conclusion: Perfusion index has a moderate and statistically significant negative correlation with SNAPPE II scores of neonates. It can therefore be used, in tandem with other assessment tools, to predict the severity of illness in neonates.