Objective: To describe a fast, simple method to acquire static pressure-volume (P-V) curve of the respiratory system and to compare it with airway occlusion technique.
Methods: ARDS sheep model was induced by intravenously infusing 3-6 micrograms/kg LPS, static P-V curves were determined by low flow technique and airway occlusion technique. Static compliance (Cst), lower inflection point (Pinfd and Pinfb) and airway pressure were compared between the two methods.
Results: Pinf were (8.91 +/- 0.82) cm H2O and (8.59 +/- 0.78) cm H2O determined by low flow technique and airway occlusion technique respectively, the correlation between which was good (r = 0.93, P < 0.05). Cst determined by low flow technique was similar to that determined by airway occlusion technique [(19 +/- 7) L/cm H2O vs (20 +/- 7) L/cm H2O, P > 0.05]. The time needed to acquire a static P-V curve by low flow technique was 3-4 minutes versus 30-35 minutes by airway occlusion technique.
Conclusion: Accuracy and reliability of low flow technique are sufficient for clinical use, it is much less time consuming than the airway occlusion technique.