Intracranial pressure responsiveness to positive end-expiratory pressure is influenced by chest wall elastance: a physiological study in patients with aneurysmal subarachnoid hemorrhage.

BACKGROUND: Respiratory system elastance (ERS) is an important determinant of the responsiveness of intracranial pressure (ICP) to positive end-expiratory pressure (PEEP). However, lung elastance (EL) and chest wall elastance (ECW) were not differentiated in previous studies. We tested the hypothesis that patients with high ECW or a high ECW/ERS ratio have greater ICP responsiveness to PEEP. METHODS: An esophageal balloon catheter was placed to measure esophageal pressure. PEEP was increased from 5 to 15 cmH2O. Airway pressure and esophageal pressure were measured and EL, ECW and ERS were calculated at the two PEEP levels. Patients were classified into either an ICP responder group or a non-responder group based on whether the change of ICP after PEEP adjustment was greater than or less than the median of the overall study population. RESULTS: The magnitude of the increase in esophageal pressure (median [interquartile range]) at end-expiratory occlusion was significantly increased in the responder group compared with that in the non-responder group (4.1 [2.7-4.1] versus 2.7 [0.0-2.7] cmH2O, p = 0.033) after PEEP adjustment. ECW and the ECW/ERS ratio were significantly higher in ICP responders than in non-responders at both low PEEP (p = 0.021 and 0.017) and high PEEP (p = 0.011 and 0.025) levels. No significant differences in ERS and EL were noted between the two groups at both PEEP levels. CONCLUSIONS: Patients with greater ICP responsiveness to increased PEEP exhibit higher ECW and a higher ECW/ERS ratio, suggesting the importance of ECW monitoring.

Effects of increased positive end-expiratory pressure on intracranial pressure in acute respiratory distress syndrome: a protocol of a prospective physiological study.

INTRODUCTION: There are concerns that the use of positive end-expiratory pressure (PEEP) in patients with brain injury may potentially elevate intracranial pressure (ICP). However, the transmission of PEEP into the thoracic cavity depends on the properties of the lungs and the chest wall. When chest wall elastance is high, PEEP can significantly increase pleural pressure. In the present study, we investigate the different effects of PEEP on the pleural pressure and ICP in different respiratory mechanics. METHODS AND ANALYSIS: This study is a prospective, single-centre, physiological study in patients with severe brain injury. Patients with acute respiratory distress syndrome with ventricular drainage will be enrolled. An oesophageal balloon catheter will be inserted to measure oesophageal pressure. Patients will be sedated and paralysed; airway pressure and oesophageal pressure will be measured during end-inspiratory occlusion and end-expiratory occlusion. Elastance of the chest wall, the lungs and the respiratory system will be calculated at PEEP levels of 5, 10 and 15 cm H2O. We will classify each patient based on the maximal ΔICP/ΔPEEP being above or below the median for the study population. 2 groups will thus be compared. ETHICS AND DISSEMINATION: The study protocol and consent forms were approved by the Institutional Review Board of Fujian Provincial Hospital. Study findings will be disseminated through peer-reviewed publications and conference presentations. TRIAL REGISTRATION NUMBER: NCT02670733; pre-results.

Better short-term efficacy of treating severe flail chest with internal fixation surgery compared with conservative treatments.

BACKGROUND: The objective of the study is to provide evidence for selecting the best treatment approach for severe flail chest by comparing surgical and conservative treatments. METHODS: This is a retrospective study in which 32 patients with severe flail chest were treated in the Fujian Provincial Hospital (China) between July 2007 and July 2012 with surgical internal rib fixation (n = 17) or conservative treatments (n = 15). Mechanical ventilation time, intensive care unit (ICU) stay time, pulmonary infection, antibiotic treatment duration, acute physiology and chronic health evaluation II (APACHE II) scores 7 and 14 days after trauma, rate of tracheostomy, and rate of endotracheal re-intubation were compared. RESULTS: One patient died in the conservative treatment group. Better short-term outcomes were observed in the surgery group, such as total mechanical ventilation time (10.5 ± 3.7 vs. 13.7 ± 4.4 days, P = 0.03), ICU stay (15.9 ± 5.0 vs. 19.6 ± 5.0 days, P = 0.05), pulmonary infection rate (58.8 % vs. 93.3 %, P = 0.02), and APACHE II scores on the 14th day (6.5 ± 3.8 vs. 10.1 ± 4.7, P = 0.02). No difference was observed in the therapeutic time of antibiotics, rate of tracheostomy, and the rate of endotracheal re-intubation between the two groups. CONCLUSIONS: Results suggest that internal fixation surgery resulted in better outcomes in the management of severe flail chest compared with conservative treatments.