How skin anatomy influences transcutaneous bilirubin determinations: an in vitro evaluation.

BACKGROUND: Transcutaneous bilirubinometry is an effective screening method for neonatal hyperbilirubinemia. Current transcutaneous bilirubin (TcB) meters are designed for the "standard" situation of TcB determinations on the forehead or sternum of term newborns. We hypothesize that skin anatomy can considerably influence TcB determinations in non-standard situations-e.g., on preterm newborns or alternative body locations. METHODS: A commercially available TcB meter (JM-105) was evaluated in vitro on phantoms that accurately mimic neonatal skin. We varied the mimicked cutaneous hemoglobin content (0-2.5 g/L), bone depth (0.26-5.26 mm), and skin maturity-related light scattering (1.36-2.27 mm-1) within the clinical range and investigated their influence on the TcB determination. To obtain a reference frame for bone depth at the forehead, magnetic resonance head scans of 46 newborns were evaluated. RESULTS: The TcB meter adequately corrected for mimicked hemoglobin content. However, TcB determinations were influenced considerably by clinically realistic variations in mimicked bone depth and light scattering (deviations up to 72 µmol/L). This greatly exceeds the specified accuracy of the device (±25.5 µmol/L). CONCLUSION: As bone depth and light scattering vary with gestational maturity and body location, caretakers should be cautious when interpreting TcB measurements on premature newborns and non-standard body locations.

Does the architectural layout of a NICU affect alarm pressure? A comparative clinical audit of a single-family room and an open bay area NICU using a retrospective study design.

OBJECTIVES: To determine differences in alarm pressure between two otherwise comparable neonatal intensive care units (NICUs) differing in architectural layout-one of a single-family room (SFR) design and the other of an open bay area (OBA) design. DESIGN: Retrospective audit of more than 2000 patient days from each NICU cataloguing the differences in the number and duration of alarms for critical and alerting alarms, as well as the interaction of clinicians with the patient monitor. SETTING: Two level 3 NICUs. RESULTS: A total of more than 150 000 critical and 1.2 million alerting alarms were acquired from the two NICUs. The number of audible alarms and the associated noise pollution varied considerably with the OBA NICU generating 44% more alarms per infant per day even though the SFR NICU generated 2.5 as many critical desaturation alarms per infant per day. CONCLUSION: Differences in the architectural layout of NICUs and the consequent differences in delays, thresholds and distribution systems for alarms are associated with differences in alarm pressure.