Objective Pain assessment in the preterm neonate ⩽32 weeks post-conceptual age continues to be plagued by confounding factors: the ability to mount a behavioural response, sedation and the use of paralytics and the skill level of the bedside nurse. Reports indicate that the neonate is undermedicated for pain and subject to detrimental physiological stress. Innovations in technology offer the potential for non-invasive reliable methods of pain assessment.
Methods Near infrared spectroscopy (NIRS) provides cerebral monitoring of tissue oxygenation status (rSO2) and blood volume. Oxygenated and deoxygenated haemoglobin absorb light at different points in the near infrared spectrum, providing bedside data to the clinician on tissue oxygen uptake. Pulsatile flow is not required as in pulse oximetry (SpO2).
Results Recent reports indicate that the rSO2 will change before the SpO2 in response to stimuli, providing an early marker for decreased oxygenation of the brain. It is well known that a pain stimulus such as a heel stick will cause a decrease in SpO2, an increase in CO2 and a compensatory response of an increase in cerebral blood flow. Alterations in cerebral peak systolic velocity and resistance have been reported as a pain response. Depending on acuity and gestational age, this response could be marked and potentially put the neonate at risk of a haemorrhagic cerebral event.
Conclusions NIRS offers the potential for a new non-invasive method of pain assessment and an early means for intervention before severe alterations in cerebral tissue oxygenation.