Efficacy of lung recruitment maneuver with high-level positive end-expiratory pressure in patients with influenza-associated acute respiratory distress: a single-center prospective study.

Current Therapeutic Research 75 (2013) 83–87 Contents lists available at ScienceDirect Current Therapeutic Research journal homepage: www.elsevier.com/locate/cuthre Efficacy of Lung Recruitment Maneuver with High-Level Positive EndExpiratory Pressure in Patients with Influenza-Associated Acute Respiratory Distress: A Single-Center Prospective Study☆ Xiaowei Liu, MD1, Tao Ma, MD1, Bo Qu, MD2, Yan Ji, MD1, Zhi Liu, MD1,n 1 2 Emergency Department, The First Affiliated Hospital of China Medical University, Shenyang, China Department of Biostatistics, School of Public Health, China Medical University, Shenyang, China a r t i c l e in fo a b s t r a c t Article history: Accepted 11 October 2013 Background: The latest data released to the public from the Chinese Ministry of Health reported 120,940 confirmed H1N1 cases and 659 deaths on the Chinese mainland. Objective: We performed a prospective, single-center study to investigate the efficacy of lung recruitment maneuver (RM) with high-level positive end-expiratory pressure (PEEP) in patients with the 2009 influenza A (H1N1)-associated acute respiratory distress syndrome (ARDS). Methods: Eighty-four patients with H1N1-associated ARDS were admitted to emergency intensive care units between October 2009 and February 2012. During pressure control ventilation, if arterial oxygen saturation (SpO2) is consistently o 88% for 4 30 minutes, an RM with high-level PEEP is performed to normalize lung volume at 30 cmH2O for 60 seconds. The RM was considered initially a responder if SpO2 increased 4 3% within 15 minutes; otherwise, an SpO2 increase o3% would be considered initially a nonresponder. Variations on oxygen metabolism and hemodynamic parameters were also measured before and after initial RM with high-level PEEP. Results: After the initial RM, 40 patients (47.6%) with influenza-associated ARDS displayed an increase ( Z3%) in SpO2 (the responder group), and 44 patients (52.4%) had no significant improvement ( o3%) in SpO2 (the nonresponder group). Among 84 patients with influenza-associated ARDS, 56 patients survived and 28 patients died. There was significant difference in mortality rate between the responder group and the nonresponder group (7 out of 40 vs 18 out of 44; P ¼ 0.019). The initial PEEP level in the responder group was lower than that of the nonresponder group (P ¼ 0.028). The initial mean duration of mechanical ventilation in the responder group was also shorter than that of the nonresponder group (P ¼ 0.011). Furthermore, the initial dynamic lung-thorax compliance was obviously higher in the initially responder group than in the nonresponder group (P ¼ 0.038). Conclusions: Initial response of lung RM with high-level PEEP may be associated with good clinical outcome of patients with influenza-associated ARDS. The initial PEEP level, duration of mechanical ventilation, and dynamic lung-thorax compliance dynamic lung-thorax compliance may be potential factors in influencing the initial response to RM. Crown Copyright & 2013 Published by Elsevier Inc. All rights reserved. Key Words: 2009 influenza A (H1N1) acute respiratory distress syndrome lung recruitment maneuver positive end-expiratory pressure Introduction The novel swine-origin influenza virus pandemic A (H1N1), which first emerged in Mexico in April 2009, had spread globally and resulted in 4 130,000 laboratory-confirmed cases and 800 ☆ This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial-No Derivative Works License, which permits non-commercial use, distribution, and reproduction in any medium, provided the original author and source are credited. n Address correspondence to: Zhi Liu, MD, Emergency Department, the First Affiliated Hospital of China Medical University, Nanjing St, No. 155, Heping District, Shenyang 110001, China. E-mail address: (Z. Liu). deaths in 4 100 countries by July 2009.1 The latest data released to the public from the Chinese Ministry of Health reported 120,940 confirmed H1N1 cases and 659 deaths on the Chinese mainland.2 Patients with H1N1 infection had greater risk of developing critical and fatal illnesses, such as severe pneumonitis, acute respiratory distress syndrome (ARDS), respiratory failure, renal failure, and multiorgan failure.3 Approximately 10% to 30% of hospitalized patients required intensive care, and 60% to 88% of intensive care patients required mechanical ventilation.4 However, several animal and clinical studies have shown that mechanical ventilation can worsen pre-existing lung injury and produce ventilatorinduced lung injury.5 Emerging evidence indicates that the use of lung-protective mechanical ventilation strategies, such as 0011-393X/$ - see front matter Crown Copyright & 2013 Published by Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.curtheres.2013.10.001 84 X. Liu et al. / Current Therapeutic Research 75 (2013) 83–87 volume- and pressure-limited ventilation, could minimize ventilator-induced lung injury and decrease short-term mortality in patients with ARDS.6,7 Therefore, in recent years, lung recruitment maneuver (RM) and optimal positive end-expiratory pressure (PEEP) during lung-protective mechanical ventilation have been widely applied to reduce lung injuries and improve outcomes in this situation. Badet et al8 confirmed that lung RM with optimal PEEP could improve oxygenation and dynamic lung-thorax compliance (Cdyn) in patients with early ARDS. Although the critical care community has generally endorsed the strategy of using lower tidal volumes and airway pressures, the optimal level of PEEP remains controversial. Several studies suggested that lung RM with higher PEEP levels could be more effective compared with lower PEEP levels,9 whereas some other studies came to the conclusion that lung RM with low-level PEEP would be more favorable.10,11 Additionally, a recent meta-analysis concluded that lung-protective mechanical ventilation with higher levels of PEEP was associated with improved survival in patients with ARDS.12 It was hypothesized that lung RM and high levels of PEEP might be therapeutic for patients with influenza-associated ARDS. Therefore, we performed a prospective, single-center study to investigate the efficacy of lung RM with high-level PEEP in patients with influenza-associated ARDS. We also attempted to point out clinical factors influencing the initial validity of RM. Our preliminary study may provide the basis for treatment plans against influenzaassociated ARDS in the future, as well as help improve the lungprotective mechanical ventilation strategy. Protocol All patients underwent pressure control ventilation through orotracheal intubation using a protective ventilatory strategy. The inspiratory plateau pressure (PIEP) was consistently o35 cmH2O with a tidal volume of 6  8 mL/kg. PEEP levels and inspired oxygen concentration were set according to different values of continuous arterial oxygen saturation (SpO2) (...truncated)