Sustained inflation and incremental mean airway pressure trial during conventional and high-frequency oscillatory ventilation in a large porcine model of acute respiratory distress syndrome

BACKGROUND: To compare the effect of a sustained inflation followed by an incremental mean airway pressure trial during conventional and high-frequency oscillatory ventilation on oxygenation and hemodynamics in a large porcine model of early acute respiratory distress syndrome. METHODS: Severe lung injury (Ali) was induced in 18 healthy pigs (55.3 ± 3.9 kg, mean ± SD) by repeated saline lung lavage until PaO(2 )decreased to less than 60 mmHg. After a stabilisation period of 60 minutes, the animals were randomly assigned to two groups: Group 1 (Pressure controlled ventilation; PCV): FIO(2 )= 1.0, PEEP = 5 cmH(2)O, V(T )= 6 ml/kg, respiratory rate = 30/min, I:E = 1:1; group 2 (High-frequency oscillatory ventilation; HFOV): FIO(2 )= 1.0, Bias flow = 30 l/min, Amplitude = 60 cmH(2)O, Frequency = 6 Hz, I:E = 1:1. A sustained inflation (SI; 50 cmH(2)O for 60s) followed by an incremental mean airway pressure (mPaw) trial (steps of 3 cmH(2)O every 15 minutes) were performed in both groups until PaO(2 )no longer increased. This was regarded as full lung inflation. The mPaw was decreased by 3 cmH(2)O and the animals reached the end of the study protocol. Gas exchange and hemodynamic data were collected at each step. RESULTS: The SI led to a significant improvement of the PaO(2)/FiO(2)-Index (HFOV: 200 ± 100 vs. PCV: 58 ± 15 and T(Ali): 57 ± 12; p < 0.001) and PaCO(2)-reduction (HFOV: 42 ± 5 vs. PCV: 62 ± 13 and T(Ali): 55 ± 9; p < 0.001) during HFOV compared to lung injury and PCV. Augmentation of mPaw improved gas exchange and pulmonary shunt fraction in both groups, but at a significant lower mPaw in the HFOV treated animals. Cardiac output was continuously deteriorating during the recruitment manoeuvre in both study groups (HFOV: T(Ali): 6.1 ± 1 vs. T(75): 3.4 ± 0.4; PCV: T(Ali): 6.7 ± 2.4 vs. T(75): 4 ± 0.5; p < 0.001). CONCLUSION: A sustained inflation followed by an incremental mean airway pressure trial in HFOV improved oxygenation at a lower mPaw than during conventional lung protective ventilation. HFOV but not PCV resulted in normocapnia, suggesting that during HFOV there are alternatives to tidal ventilation to achieve CO(2)-elimination in an "open lung" approach

A randomized controlled trial

Objective We report on the effect of hemoadsorption therapy to reduce cytokines in septic patients with respiratory failure. Methods This was a randomized, controlled, open-label, multicenter trial. Mechanically ventilated patients with severe sepsis or septic shock and acute lung injury or acute respiratory distress syndrome were eligible for study inclusion. Patients were randomly assigned to either therapy with CytoSorb hemoperfusion for 6 hours per day for up to 7 consecutive days (treatment), or no hemoperfusion (control). Primary outcome was change in normalized IL-6-serum concentrations during study day 1 and 7. Results 97 of the 100 randomized patients were analyzed. We were not able to detect differences in systemic plasma IL-6 levels between the two groups (n = 75; p = 0.15). Significant IL-6 elimination, averaging between 5 and 18% per blood pass throughout the entire treatment period was recorded. In the unadjusted analysis, 60-day-mortality was significantly higher in the treatment group (44.7%) compared to the control group (26.0%; p = 0.039). The proportion of patients receiving renal replacement therapy at the time of enrollment was higher in the treatment group (31.9%) when compared to the control group (16.3%). After adjustment for patient morbidity and baseline imbalances, no association of hemoperfusion with mortality was found (p = 0.19). Conclusions In this patient population with predominantly septic shock and multiple organ failure, hemoadsorption removed IL-6 but this did not lead to lower plasma IL-6-levels. We did not detect statistically significant differences in the secondary outcomes multiple organ dysfunction score, ventilation time and time course of oxygenation

High frequency oscillatory ventilation and prone positioning in a porcine model of lavage-induced acute lung injury

BACKGROUND: This animal study was conducted to assess the combined effects of high frequency oscillatory ventilation (HFOV) and prone positioning on pulmonary gas exchange and hemodynamics. METHODS: Saline lung lavage was performed in 14 healthy pigs (54 ± 3.1 kg, mean ± SD) until the arterial oxygen partial pressure (PaO(2)) decreased to 55 ± 7 mmHg. The animals were ventilated in the pressure controlled mode (PCV) with a positive endexpiratory pressure (PEEP) of 5 cmH(2)O and a tidal volume (V(T)) of 6 ml/kg body weight. After a stabilisation period of 60 minutes, the animals were randomly assigned to 2 groups. Group 1: HFOV in supine position; group 2: HFOV in prone position. After evaluation of prone positioning in group 2, the mean airway pressure (P(mean)) was increased by 3 cmH(2)O from 16 to 34 cmH(2)O every 20 minutes in both groups accompanied by measurements of respiratory and hemodynamic variables. Finally all animals were ventilated supine with PCV, PEEP = 5 cm H(2)O, V(T )= 6 ml/kg. RESULTS: Combination of HFOV with prone positioning improves oxygenation and results in normalisation of cardiac output and considerable reduction of pulmonary shunt fraction at a significant (p < 0.05) lower P(mean )than HFOV and supine positioning. CONCLUSION: If ventilator induced lung injury is ameliorated by a lower P(mean), a combined treatment approach using HFOV and prone positioning might result in further lung protection

Hepatic effects of lung protective pressure controlled ventilation and a combination of high frequency oscillatory ventilation and extracorporeal lung assist in experimental lung injury

Background: Ventilation with high positive end-expiratory pressure (PEEP) can lead to hepatic dysfunction. The aim of this study was to investigate the hepatic effects of strategies using high airway pressures either in pressure-controlled ventilation (PCV) or in high-frequency oscillatory ventilation (HFOV) combined with an arteriovenous extracorporeal lung assist (ECLA). Material/Methods: Pietrain pigs underwent induction of lung injury by saline lavage. Ventilation was continued for 24 hours either as PCV with tidal volumes of 6 ml/kg and PEEP 3 cmH2O above the lower inflection point of the pressure-volume curve or as HFOV (≥12 Hz) with a mean tracheal airway pressure 3 cmH2O above the lower inflection point combined with arteriovenous ECLA (HFOV+ECLA). Fluids and norepinephrine stabilized the circulation. The indocyanine green plasma disappearance rate, serum bilirubin, aspartate aminotransferase, alanine aminotransferase, γ-glutamyltransferase, alkaline phosphatase, glutamate dehydrogenase, lactate dehydrogenase and creatine kinase were determined repeatedly. Finally, liver neutrophils were counted and liver cell apoptosis was assessed by terminal deoxynucleotidyl transferase nick end labeling (TUNEL). Results: Aspartate aminotransferase increased in the PCV group about three-fold and in the HFOV+ECLA group five-fold (p&lt;0.001). Correspondingly, creatine kinase increased about two-fold and four-fold, respectively (p&lt;0.001). Lactate dehydrogenase was increased in the HFOV+ECLA group (p&lt;0.028). The number of neutrophils infiltrating the liver tissue and the apoptotic index were low. Conclusions: High airway pressure PCV and HFOV with ECLA in the treatment of lavage-induced lung injury in pigs did not cause liver dysfunction or damage. The detected elevation of enzymes might be of extrahepatic origin

Characterization of critically ill patients with septic shock and sepsis‐associated cardiomyopathy using cardiovascular MRI

Abstract Aims Sepsis‐induced cardiomyopathy is a major complication of septic shock and contributes to its high mortality. This pilot study investigated myocardial tissue differentiation in critically ill, sedated, and ventilated patients with septic shock using cardiovascular magnetic resonance (MR). Methods and results Fifteen patients with septic shock were prospectively recruited from the intensive care unit. Individuals received a cardiac MR scan (1.5 T) within 48 h after initial catecholamine peak and a transthoracic echocardiography at 48 and 96 h after cardiac MR. Left ventricular ejection fraction was assessed using both imaging modalities. During cardiac MR imaging, balanced steady‐state free precession imaging was performed for evaluation of cardiac anatomy and function in long‐axis and short‐axis views. Native T1 maps (modified Look–Locker inversion recovery 5 s(3 s)3 s), T2 maps, and extracellular volume maps were acquired in mid‐ventricular short axis and assessed for average plane values. Patients were given 0.2 mmol/kg of gadoteridol for extracellular volume quantification and late gadolinium enhancement imaging. Critical care physicians monitored sedated and ventilated patients during the scan with continuous invasive monitoring and realized breathholds through manual ventilation breaks. Laboratory analysis included high‐sensitive troponine T and N terminal pro brain natriuretic peptide levels. Twelve individuals with complete datasets were available for analysis (age 59.5 ± 16.9 years; 6 female). Nine patients had impaired systolic function with left ventricular ejection fraction (LVEF) < 50% (39.8 ± 5.7%), and three individuals had preserved LVEF (66.9 ± 6.7%). Global longitudinal strain was impaired in both subgroups (LVEF impaired: 11.0 ± 1.8%; LVEF preserved: 16.0 ± 5.8%; P = 0.1). All patients with initially preserved LVEF died during hospital stay; in‐hospital mortality with initially impaired LVEF was 11%. Upon echocardiographic follow‐up, LVEF improved in all previously impaired patients at 48 (52.3 ± 9.0%, P = 0.06) and 96 h (54.9 ± 7.0%, P = 0.02). Patients with impaired systolic function had increased T2 times as compared with patients with preserved LVEF (60.8 ± 5.6 ms vs. 52.2 ± 2.8 ms; P = 0.02). Left ventricular GLS was decreased in all study individuals with impaired LVEF (11.0 ± 1.8%) and less impaired with preserved LVEF (16.0 ± 5.8%; P = 0.01). T1 mapping showed increased T1 times in patients with LVEF impairment as compared with patients with preserved LVEF (1093.9 ± 86.6 ms vs. 987.7 ± 69.3 ms; P = 0.03). Extracellular volume values were elevated in patients with LVEF impairment (27.9 ± 2.1%) as compared with patients with preserved LVEF (22.7 ± 1.9%; P < 0.01). Conclusions Septic cardiomyopathy with impaired LVEF reflects inflammatory cardiomyopathy. Takotsubo‐like contractility patterns occur in some cases. Cardiac MR is safely feasible in critically ill, sedated, and ventilated patients using extensive monitoring and experienced staff. Trial Registration: retrospectively registered (ISRCTN85297773