Inspiratory work of breathing in ventilated preterm infants

✍ Scribed by H. Lorino; G. Moriette; C. Mariette; A-M. Lorino; A. Harf; P.-H. Jarreau

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 471 KB
• Volume: 21
• Category: Article
• ISSN: 8755-6863
• DOI: 10.1002/(sici)1099-0496(199605)21:5<323::aid-ppul8>3.0.co;2-n

✦ Synopsis

In ventilated newborns, part of the inspiratory work of breathing (WOB) may be due to the inspiratory efforts preceding inspiratory ventilator flow. This study was designed to quantify the contribution of these efforts to WOB. WOB was evaluated in six intubated preterm infants ventilated by the Drager Babylog 8000. The ventilatory modes studied were intermittent mandatory ventilation (IMV), continuous positive airway pressure (CPAP), and assist-control ventilation at 10 (ACV, , , ) and 15 (ACV,,) cmH,O peak pressure. Mouth flow (V) and esophageal pressure (Pe) were recorded, and WOB was estimated from the area delineated by the esophageal pressure-volume curve, where volume is the time integral of V. Calculation of WOB started either at the onset of the infant's inspiratory flow (WOB'), or at the beginning of the infant's inspiratory muscle efforts, detected on Pe and confirmed on the V tracing (WOB,). WOB, was found to be significantly higher than WOBl under all ventilatory conditions studied. The difference in work of breathing (AW) between WOB, and WOB, did not depend on the type of ventilatory mode. When AW was related to WOB, , it amounted to about 30% of WOB, in IMV and CPAP, and 60% in ACV ( P < 0.05, ACVIS vs. IMV). These results suggest that, in preterm infants connected to a ventilator, inspiratory efforts preceding flow inspiration might account for a large fraction of the inspiratory work of breathing.