748 - Continuous Hemodynamic Monitoring of Cardiac Output (CO) to Assess Extubation Readiness Characteristics in Very Low Birth Weight Infants

Predicting extubation readiness and those that may fail correlates with subsequent respiratory morbidities. (JPED 252:124-130.e3, 2023). One posited factor is cardiovascular fitness, and the influence of reflex response to stress on adaptive blood flow. Adult literature suggests increase in post-extubation CO to correlate with success (AJRCCM 158:1763, 1998). We aim to explore adaptive factors in the neonate, assessing heart rate (HR) and CO. We hypothesize continuous assessment of CO in VLBWs may elucidate cardiovascular readiness for respiratory wean.

Objective: To determine whether cardiac responsiveness to extubation will predict success over the next 4d.

Design/Methods:

Nineteen VLBW neonates with birth GA 22-30w, birthweight < 1500g were evaluated for continuous CO using electrical velocimetry (ICON^TM, Osypka Medical, Cardiotronic) during elective extubation to non-invasive support, with extubation criteria of mean airway pressure< 10cmH₂O, RR< 65/m, pH >7.3, and pCO₂< 60. HR, stroke volume (SV), and CO were continuously monitored in the hour prior to and after extubation. Fischer’s analysis assessed for changes in HR and CO.

Results:

Demographics were similar for all patients (Table). Of 15 successful extubations, 93% showed an increase in CO or HR in the hour after versus before extubation, while just 25% of failed extubations increased (n=4, Fischer’s p< 0.009), (Figure). Four subsets emerged (Table II). In those succeeding, where CO increased, HR and RR decreased, consistent with less work of breathing. Those with the highest increase in RR without cardiovascular response failed, apparently unable to accommodate increased RR work. A 3^rd group with less elevation in RR but increased HR succeeded, presumed due to increased sympathetic tone to meet respiratory work. A 4th group had the largest increase in BP, associated with hypoxemia from apnea and failure.

Conclusion(s): We speculate that the association between successful extubation and capacity for increased cardiovascular function as early as 1 hr after ET removal is evidence of sufficient sympathetic nervous system driven cardiac reserve capacity to cope with the change in lung mechanics/work. Electric velocimetry may aid in early prediction of success before respiratory deterioration. A larger sample size and other measures of sympathetic tone (e,g,urine catecholamines or Fourier beat-to-beat HR variability) are needed to confirm this.