ARDS患者的肺复张.ppt

How high a pressure?How long a time? - healthy lung transpulmonary pressure of 30 cmH2O to recruit atelectatic healthy lungs Greaves et al JAP 1990 peak alveolar pressures of 40 cmH2O for 7 to 15 seconds to recruit lungs of previously healthy normal patients following 20 minutes of general anesthesia by Rothen et al Br J Anaesth 1993, 1998 resolution of atelectasis during a 40 cmH2O RM has a time constant of 2.6 sec Rothen et al Br J Anaesth 1999 How high a pressure?How long a time? - healthy lung As a result in previously healthy individuals the vast majority of atelectasis would be recruited within about 7-8 sec How high a pressure?How long a time? - animal peak airway pressures of 55 cmH2O for 5 – 10 min to open collapsed lung in a porcine model of ARDS Sjosrand et al ICM 1995 to maximally recruit lung in a sheep saline lavage lung injured model 40 cmH2O PEEP, 20 cmH2O PC, Ppeak 60 cmH2O, I:E of 1:1, and a rate of 10 bpm for 2 minutes Fujino et al AJRCCM 1999 How high a pressure?How long a time? - animal animals recruited with 40 cmH2O CPAP for 60 sec not maximally recruited to fully recruit the lung multiple (2-3) RMs required even at peak pressures of 60 cmH2O How high a pressure?How long a time? - patient peak airway pressure of 46 cmH2O to recruit collapsed lung in ARDS patients Gattinoni et al AJRCCM 1986 35 – 40 cmH2O CPAP for 30 – 40 sec prior to establishing a lung protective ventilatory strategy whenever mechanical ventilation was disrupted Amato et al NEJM 1998 How high a pressure?How long a time? - patient In a patient with septic ARDS initial recruitment maneuvers with 40 cmH2O CPAP for 40 sec failed PEEP 40 cmH2O PEEP and PCV 20 cmH2O at an I:E ratio of 1:1 with a rate of 10 bpm for 2 minutes to fully recruit the lung Medoff et al CCM 2000 How high a pressure?How long a time? - patient The success of PC vs CPAP in the examples emphasize the relationship between pressure and time Fujino et al AJRCCM 1999 Medoff et al CCM 2000 The optimal r