We greatly appreciate the letter by Dr Bingyang and colleagues [1] concerning our recent study focused on pulsatile pulmonary perfusion (PPP) as a mean to improve perioperative lung protection and postoperative respiratory function [2]. Concerning the design of the study, the criticism raised by Dr Bingyang is conceivable and their suggested approach was indeed considered at the beginning. The randomization to three study groups however was discouraged based on: (1) the availability of previous observations proving the efficacy on pulmonary function of continuous lung perfusion with oxygenated blood only [3]; (2) the higher number of patients required to achieve a proper statistical power and the potential relative weakness of the mandatory post-hoc analysis; and, (3) finally, this being the first use of PPP in humans, we elected to investigate mainly its safety and efficacy versus conventional control as the primary purpose of the study. Concerning the setting of the cardiopulmonary bypass, the pulmonary line arose from the arterial line by means of a ‘Y’ connector located at post-oxygenator site, and incorporated a pulsatile pump (Jostra, Maquet Cardiopulmonary, Hirrlingen, Germany) set at a rate of 60 bpm. Pulmonary baseline flow was established at 10% of global pulmonary flow which was run at 7 ml kg1 min1. This value proved to be the minimal flow able to generate a physiologic pulsatile perfusion, defined on the basis of surplus hemodynamic energy (SHE). Pulsation started when 20% of the cycle length within a single beat was reached, and ended at 80% of it. Concerning the extra energy pressure (EEP) and SHE, our calculations were entirely based on the Shepard formula [4]. As demonstrated by Undar, a difference between the EEP and the mean arterial pressure (MAP) of 10—12% can be considered a physiologic pulsatile perfusion [5]. Accordingly, we found with a pulmonary flow of 7 ml kg1 min1 an ‘EEP— MAP’ (SHE) of 10%, therefore within the considered spectrum for a proper definition of PP. Once again we thank Dr Bingyang and colleagues for sharing with us their very stimulating observations, and we hope that this discussion will encourage further studies on a very intriguing topic.
Reply to Bingyang et al.
SANTINI, Francesco;Onorati F.;FAGGIAN, Giuseppe;MAZZUCCO, Alessandro
2011-01-01
Abstract
We greatly appreciate the letter by Dr Bingyang and colleagues [1] concerning our recent study focused on pulsatile pulmonary perfusion (PPP) as a mean to improve perioperative lung protection and postoperative respiratory function [2]. Concerning the design of the study, the criticism raised by Dr Bingyang is conceivable and their suggested approach was indeed considered at the beginning. The randomization to three study groups however was discouraged based on: (1) the availability of previous observations proving the efficacy on pulmonary function of continuous lung perfusion with oxygenated blood only [3]; (2) the higher number of patients required to achieve a proper statistical power and the potential relative weakness of the mandatory post-hoc analysis; and, (3) finally, this being the first use of PPP in humans, we elected to investigate mainly its safety and efficacy versus conventional control as the primary purpose of the study. Concerning the setting of the cardiopulmonary bypass, the pulmonary line arose from the arterial line by means of a ‘Y’ connector located at post-oxygenator site, and incorporated a pulsatile pump (Jostra, Maquet Cardiopulmonary, Hirrlingen, Germany) set at a rate of 60 bpm. Pulmonary baseline flow was established at 10% of global pulmonary flow which was run at 7 ml kg1 min1. This value proved to be the minimal flow able to generate a physiologic pulsatile perfusion, defined on the basis of surplus hemodynamic energy (SHE). Pulsation started when 20% of the cycle length within a single beat was reached, and ended at 80% of it. Concerning the extra energy pressure (EEP) and SHE, our calculations were entirely based on the Shepard formula [4]. As demonstrated by Undar, a difference between the EEP and the mean arterial pressure (MAP) of 10—12% can be considered a physiologic pulsatile perfusion [5]. Accordingly, we found with a pulmonary flow of 7 ml kg1 min1 an ‘EEP— MAP’ (SHE) of 10%, therefore within the considered spectrum for a proper definition of PP. Once again we thank Dr Bingyang and colleagues for sharing with us their very stimulating observations, and we hope that this discussion will encourage further studies on a very intriguing topic.
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