Systematic review and meta-analysis of olfactive stimulation interventions to manage procedural pain in preterm and full-term neonates

Abstract

Background Preterm and full-term neonates undergo many painful procedures during their hospitalization in the neonatal intensive care unit. Unrelieved and repeated pain can have important repercussions on their motor and intellectual development. Still, pain management interventions are limited for neonates.

Objective This systematic review aimed to evaluate the effectiveness of olfactive stimulation interventions on the pain response of preterm and full-term infants during painful procedures.

Design Systematic review and meta-analysis.

Data sources An electronic search was conducted from inception to August 2019 in PubMed, MEDLINE, Embase, CINAHL, PsycINFO, Web of Sciences, CENTRAL, Scopus and ProQuest.

Review methods Study selection, data extraction, assessment of risk of bias and quality of evidence were performed by two independent reviewers.

Results 3311 studies were screened. Of the 14 studies included studies (n = 1028 infants), results from 10 were combined in meta-analysis. The latter demonstrated that olfactive stimulation interventions using a familiar odor were effective compared to standard care on pain reactivity (SMD -0.69; 95% CI -0.93 to -0.44; I2 = 20%, p < 0.00001), pain regulation (SMD -0.40; 95% CI -0.66 to -0.14; I2 = 13%, p = 0.002), crying duration during (SMD -0.42; 95% CI -0.73 to -0.10; I2 = 47%, p = 0.009) and after the procedure (SMD -0.37; 95% CI -0.68 to -0.07; I2 = 0%, p = 0.01), heart rate after the procedure (MD -3.87; 95% CI -7.36 to -0.38; I2 = 99%, p = 0.03), oxygen saturation during (MD -0.47; 95% CI -0.86 to -0.08; I2 = 91%, p = 0.02) and after the procedure (MD -0.56; 95% CI -0.99 to -0.13; I2 = 99%, p = 0.01). No adverse event was reported.

Conclusion These findings are based on low to very low quality of evidence limiting our confidence in effect estimates. More rigorous trials with a larger sample size are needed to enhance the comprehension of the mechanisms underlying olfactive stimulation interventions and the interventions’ efficacy.