TY - JOUR T1 - Effects of Continuous Positive Airway Pressure/Positive End-Expiratory Pressure and Pressure-Support Ventilation on Work of Breathing, Using an Animal Model JF - Respiratory Care SP - 689 LP - 696 VL - 48 IS - 7 AU - Mark J Heulitt AU - Shirley J Holt AU - Tracy L Thurman AU - Sterling Wilson AU - Renée A Hall Y1 - 2003/07/01 UR - http://rc.rcjournal.com/content/48/7/689.abstract N2 - OBJECTIVE: Evaluate the effects of continuous positive airway pressure (CPAP)/positive endexpiratory pressure (PEEP) and pressure support ventilation (PSV) on work of breathing (WOB). METHODS: With 13 anesthetized lambs we measured WOB with an esophageal balloon and flow signals. All the animals were sedated, intubated, and ventilated, using 2 pediatric ventilators (Servo 300 and VIP Bird). Ventilator settings were CPAP of 0, 5, and 10 cm H2O and PSV of 5 and 10 cm H2O with PEEP of 0, 5, and 10 cm H2O. Data were analyzed with 2-way analysis of variance. RESULTS: With the Servo 300 the total WOB (WOBT) increased between CPAP/PEEP of 0 and 10 cm H2O (p ≤ 0.0001) and between CPAP/PEEP of 5 and 10 cm H2O (p ≤ 0.0002). With the Servo 300 the addition of PSV decreased WOBT (p ≤ 0.003). With the VIP Bird the WOBT significantly increased between CPAP/PEEP of 0 and 10 cm H2O (p ≤ 0.02) and between CPAP/PEEP of 5 and 10 cm H2O (p ≤ 0.03). With PSV the WOBT was lower only at PSV 10 cm H2O (p ≤ 0.0001). CONCLUSIONS: WOBT increased as CPAP/PEEP was increased, and PSV lowered WOBT. We hypothesize that in a healthy animal model increased CPAP/PEEP may cause alveolar overdistention. ER -