The present study aimed to assess the intensity of pain and its temporal association. Furthermore, data were collected for various other parameters during the same duration to investigate their prevalence, temporal trends, and potential relationship with pain. Our study intended to look for the effect of pain for a longer duration and included various other parameters like feed intolerance, apnea and increase in oxygen requirement in the single trial.
The median PIPP-R score rapidly increased immediately after the screening procedure. Approximately 59% of the neonates had severe pain and 24% of neonates had slight to moderate pain immediately after screening. Similar findings have been described by Slevin M et. al.18 whose study also suggested that neonates had tachycardia and increased crying time immediately after ROP screening and Belda et. al. 12 showed that the CRIES score increased immediately after ROP screening. In 2019, Avila Alvarez A et. Al. showed that 47% of neonates had a PIPP-R score of more than 12, signifying severe pain. 12 Similar findings were also described in past by Laws D et. al. 19 and Ryan R et. al. 20 showed that there were desaturations and tachycardia after ROP screening
We found that after 30 minutes of the screening procedure, pain reduced to some extent but still 52% of the neonates had slight to moderate pain which reduced at 6 hours to a significant extent. By applying time regression analysis, results suggest that there was a rapid decrease in pain for up to 6 hours. Comparable results were published by Kleberg et. al. 13 showed that increased salivary cortisol at 60 minutes post-procedure decreased at 4 hours. Subsequently, at 24 hours and 48 hours after screening, only 4% and 1% of neonates had slight to moderate pain respectively with a median score touching baseline at 48 hours suggesting that neonates did not suffer from pain at this time point. In contrast, Belda et. al. 12 showed that pain scores remained doubled in infants after 24 hours of screening. A possible explanation for the difference between these two results could be the change in the practice of comfort care and the use of pharmacological agents (topical anaesthesia) before the screening procedure. Based on the study findings, it was observed that neonates experienced persistent and intense pain following ROP screening, despite the application of both non-pharmacological and pharmacological interventions aimed at mitigating pain during the procedure. Therefore, we recommend the incorporation of supplementary pharmacological measures, including oral administration of paracetamol, to effectively alleviate pain during and after the screening procedure. In our study, we found out that 28% of episodes of apnea occurred within 6 hours and 72% of episodes occurred between 6 hours – 48 hours of ROP screening, but this was not statistically significant. Similar results were published in the past by Belda S et. al. 12 showed an increase in episodes of apnea in about 47% of neonates (n = 27) with 4% requiring transfer to ICU because of severe apneas. However, none of our neonates required shifting to ICU care. Mitchell et. Al. 21 showed a significant increase in apnea events from 25–48 hours of screening as compared to within 24 hours. These warrant monitoring neonates for a longer duration as other contributing factors could result in an increased incidence of apnea.
We also found out that six neonates had feed intolerance within 6 hours and the rest of the six neonates had incidents after 6 hours of the procedure. Previous studies have revealed similar findings by Belda et. al. 12 showed that 4% of neonates had vomiting episodes and 22% had increased gastric aspirates. The physiological responses associated with the screening procedure remained an immediate effect. Whereas, delayed apnea incidence and feed intolerance from our study suggest the possibility of other causes as acute pain is not associated with delayed apnea events.
The strengths of the study are its prospective scoring of the PIPP-R score and recording of various other variables for all neonates till 48 hours of ROP screening. Initially, to maintain standardization and limit error, the principal investigator scored 10 videos individually and got verification by the consultant for each. The videos were separately scored by the registrar with a good interclass correlation coefficient. The limitation of the study was its small sample size to find a significant association between the duration or severity of pain with the assumed risk factors. In addition, the PIPP-R score has its limitation in measuring pain over 48 hours after the event. Also, we did not assess the impact of severe pain on the subsequent behavioural development of our enrolled neonates.
The results of the study might apply to neonates undergoing different procedures, however, further research should be done with a larger sample size before generalising the results. Further studies are needed to recognise the effect of various factors such as gestation, weight (at examination), and medical co-morbidities such as intraventricular haemorrhage on the severity or duration of pain as well as their correlation with other adverse outcomes following ROP screening.