Current state of noninvasive, continuous monitoring modalities in pediatric anesthesiology.
The increase in safety in anaesthesia is at least partly attributable to the improvement of intraoperative monitoring. This review examines the literature to ascertain the status of development and evidence around continuous, non-invasive monitoring modalities used in the paediatric population undergoing anaesthesia for non-cardiac surgery. The modalities examined include haemodynamic monitoring (continuous non-invasive blood pressure), non-invasive cardiac output monitors, near-infrared spectrometry (NIRS) and transcutaneous blood gas analysis.
Take home messages
- Non-invasive blood pressure measurements – NIBP is generally lower when taken from the leg compared to the arm in the paediatric population (converse to the adult population). Continuous measurements of blood pressure using finger clamp cuff technology generally provides accurate diastolic and mean arterial pressure but under-reads the systolic blood pressure.
- Cardiac output monitoring – various techniques are available and include pulse contour analysis (from a non-invasive blood pressure finger cuff technique), bioimpedance and bioreactance. No method has currently demonstrated sufficient accuracy with up to 45% error reported compared to the gold standard of an invasive thermodilution technique.
- Near infra-red spectrometry (NIRS) – NIRS measures the regional tissue oxygenation (r-SO2) and is not a form of pulse oximetry. An absolute lowest NIRS value for safety is still yet to be defined. However, a reduction of 20% from baseline has been shown to negatively impact patient outcome. Combing NIRS with a measurement of peripheral muscle regional tissue oxygen to produce a ratio is an area of growing interest and could provide an early identification of centralisation.
- Transcutaneous blood gas analysis – this method of measuring carbon dioxide is useful for those patients without instrumented airways. It functions by heating the skin locally to enable diffusion of carbon dioxide through the skin to be measured. This method is accurate and has been shown to be more closely correlated to PaCO2 than end tidal CO2.
Reviewed by Gihan Ganesh