Positioning During SBT in NICU Infants

Mechanical ventilation is a life-sustaining intervention in premature infants with respiratory difficulties. There is relative consensus when to intubate and provide positive pressure mechanical ventilation in the presence of respiratory failure. In contrast, discontinuation of mechanical ventilation during recovery remains largely subjective. Typically 25% of infants weighing \<1500g who are extubated using these criteria require reintubation suggesting that the ability of clinicians to predict successful extubation is limited. A potential predictive tool for neonatal extubation is the Spontaneous Breathing Trial (SBT). The efficacy of SBT or other tests used in older patient populations in improving clinical judgment is questionable in the neonatal population with its unique physiology, respiratory mechanics and drive factors.

Christiana Care Health System NICU currently uses the SBT as a standard part of neonatal assessment for extubation from mechanical ventilation.

The SBT used at CCHS is a non-invasive 5-minute test performed on an intubated infant. Respiratory rates (RR), expired tidal volume (Vte), heart rate, and oxygen saturation by pulse oximetry (SpO2) are recorded. An SBT is considered passed, when there is no apnea (defined as no respiratory effort for greater than 20 seconds), no bradycardia (defined as heart rate less than 100 for greater than 15 seconds), and the SpO2 has been maintained at greater than 85% or SBT VE greater than 60% than that of the mechanical VE.

Potentially confounding the SBT, and unstudied, is the effect of position (prone, supine, lateral). Similar to adults, infant position has a significant effect on the efficacy of spontaneous breathing. Infants in the CCHS NICU are routinely cared for in multiple positions (prone, supine, lateral) throughout the day. What is unknown is the impact of infant positioning on the SBT. An SBT performed in one position may not predict infant respiratory status after extubation in another position. Understanding the impact of infant positioning and work of breathing indices independently or in combination with an SBT will aid clinicians in decision-making and potentially decrease neonatal morbidity (inaccuracy with timing and safety of extubation). This pilot study will begin to explore these clinically relevant factors.

Work of breathing (WOB) indices can be non-invasively measured utilizing respiratory inductive plethysmography (RIP). WOB indices measured by RIP have been utilized by this research team for clinical and research purposes, including at CCHS. RIP entails that an infant breathe calmly while wearing soft elastic cloth bands that comfortably encircle the rib cage and abdomen. Contained within the bands is a flexible sinusoidal wire that measures motion. Measurements are taken for a minimum of 10 breaths, but preferable throughout the duration of the 5 minutes SBT.

Objectives: This pilot study will investigate the (1) role of infant position on SBT score and (2) the relationship of work of breathing indices in reference to the SBT score and infant position.