Michela Bombino

Relationships between lung computed tomographic density, gas exchange, and PEEP in acute respiratory failure.

Twenty-two patients with acute respiratory failure underwent lung computed tomography (CT) and physiological measurements at 5, 10, and 15 cm H2O positive end-expiratory pressure (PEEP) to investigate the relationship between morphology and function. Lung densities were primarily concentrated in the dependent regions. From the frequency distribution of CT numbers (difference in xray attenuation between water and lung) and lung gas volume measurements the authors obtained a quantitative estimate of normally inflated, poorly inflated, and non-inflated lung tissue weight. This estimated average lung weight was increased twofold nbove normal and excess lung weight correlated with the mean pulmonary artery pressure (P < 0.01). Venous admixture correlated with the non-inflated tissue mass (P < 0.01). Increasing PEEP caused progressive clearing of radiographic densities and increased the mass of normally inflated tissue (anatomic recruitment), while reducing venous admixture. The cardiac index decreased after increasing PEEP while oxygen delivery was unchanged. The authors conclude that CT scan lung density and oxygen exchange efficiency are correlated; the main effect of augmenting PEEP is to recruit perfused alveolar units that were previously collapsed.

Pentraxin 3 in acute respiratory distress syndrome: an early marker of severity.

Objective:Pentraxin 3 is a fluid phase receptor involved in innate immunity. It belongs to the Pentraxins family, as C-reactive protein does. Pentraxin 3 is produced by a variety of tissue cells, whereas only the liver produces C-reactive protein. Pentraxin 3 plays a unique role in the regulation of inflammation. Acute lung injury and acute respiratory distress syndrome are characterized by an important inflammatory reaction. We investigated the role of pentraxin 3 as a marker of severity and outcome predictor of acute lung injury and acute respiratory distress syndrome. Design:We measured circulating pentraxin 3 and C-reactive protein levels within 24 hrs from intubation (day 1), after 24 hrs from the first sample, then every 3 days for the first month and then once a week, until discharge from the intensive care unit. Pentraxin 3 was also measured in bronchoalveolar lavages, performed when clinically indicated. Setting:One university medical center general intensive care unit. Patients:The study included 21 patients affected by acute lung injury and acute respiratory distress syndrome (1994 Consensus Conference criteria). Interventions:None. Measurements and Main Results:Pentraxin 3 plasma levels were high with a peak on the first day (median 71.05 ng/mL, interquartile range 52.37-117.38 ng/mL, normal values <2 ng/mL), declining thereafter. C-reactive protein peaked later and remained at relatively high values. Out of several day 1 parameters, pentraxin 3 was the only significant difference between survivors and nonsurvivors. Pentraxin 3 levels were positively correlated with lung injury score values (p < 0.001) and number of organ failures (p < 0.001). Pentraxin 3 was present in bronchoalveolar lavages fluids (5.03 ng/mL, interquartile range 1.52-8.48 ng/mL) and bronchoalveolar lavages positive to bacterial culture were associated with significantly higher pentraxin 3 values (p < 0.05). Conclusions:The results presented here show that pentraxin 3 is elevated in acute lung injury and acute respiratory distress syndrome and that its levels correlate with parameters of lung injury and systemic involvement. The clinical and pathophysiological significance of pentraxin 3 in acute lung injury and acute respiratory distress syndrome deserves further scrutiny.

Percutaneous bridge to heart transplantation by venoarterial ECMO and transaortic left ventricular venting.

We report a case in which life support for cardiogenic shock was achieved by a nonpulsatile venoarterial bypass, and left ventricular decompression was obtained by a catheter placed percutaneously through the aortic valve into the left ventricle. The blood drained from the left ventricle was pumped into the femoral artery. The normalization of left heart filling pressures allowed the resolution of pulmonary edema, and the patient underwent a successful heart transplantation following 7 days of mechanical cardiocirculatory support.

Extracorporeal membrane oxygenation for interhospital transfer of severe acute respiratory distress syndrome patients: 5-year experience.

Purpose Transfer of severely hypoxic patients is a high-risk procedure. Extracorporeal Membrane Oxygenation (ECMO) allows safe transport of these patients to tertiary care institutions. Our ECMO transportation program was instituted in 2004; here we report results after 5 years of activity. Methods This is a clinical observational study. Criteria for ECMO center activation were: potentially reversibile respiratory failure, PaO2 <50 mmHg with FiO2 >0.6 for >12 hours, PEEP >5 cmH20, Lung Injury Score (LIS) ≥3 or respiratory acidosis with pH <7.2, no intracranial bleeding, and no absolute contraindication to anticoagulation. If eligible, a skilled crew applied ECMO at the referral hospital. Transportation was performed with a specially equipped ambulance. Results Sixteen patients were possible candidates for ECMO transfer. Two patients were excluded while 14 (mean±SD, age 35.4±18.6, SOFA 8.4±3.7, Oxygenation Index 43.7±13.4) were transported to our institution (distance covered 102±114 km, global duration of transport 589±186 minutes). Two patients improved after iNO-trial and were transferred and subsequently managed without ECMO. The remaining 12 patients were transferred on veno-venous ECMO with extracorporeal blood flow 2.7±1 L·min−1, gas flow 3.8±1.8 L·min−1, and FiO2 1. Data were recorded 30 minutes before and 60 minutes after initiation of ECMO. ECMO improved PCO2 (75±23 vs. 53±9 mmHg, p<0.01) thus improving pH (7.28±0.13 vs. 7.39±0.05, p<0.01) and allowing a reduction in respiratory rate (35±14 vs. 10±4 breaths/min, p<0.01), minute ventilation (10.1±3.8 vs. 3.7±1.7 L·min−1, p<0.01), and mean airway pressure (26±6.5 vs. 22±5 cmH2O, p<0.01). No major clinical or technical complications were observed. Conclusions ECMO effectively enabled high-risk ground transfer of severely hypoxic patients.

Alveolar pentraxin 3 as an early marker of microbiologically confirmed pneumonia: a threshold-finding prospective observational study

IntroductionTimely diagnosis of pneumonia in intubated critically ill patients is rather challenging. Pentraxin 3 (PTX3) is an acute-phase mediator produced by various cell types in the lungs. Animal studies have shown that, during pneumonia, PTX3 participates in fine-tuning of inflammation (for example, microbial clearance and recruitment of neutrophils). We previously described an association between alveolar PTX3 and lung infection in a small group of intubated patients. The aim of the present study was to determine a threshold level of alveolar PTX3 with elevated sensitivity and specificity for microbiologically confirmed pneumonia.MethodsWe recruited 82 intubated patients from two intensive care units (San Gerardo Hospital, Monza, Italy, and Massachusetts General Hospital, Boston, MA, USA) undergoing bronchoalveolar lavage (BAL) as per clinical decision. We collected BAL fluid and plasma samples, together with relevant clinical and microbiological data. We assayed PTX3 and soluble triggering receptor expressed on myeloid cells 1 (sTREM-1) in BAL fluid and PTX3, sTREM-1, C-reactive protein (CRP) and procalcitonin (PCT) in plasma. Two blinded independent physicians reviewed patient data to confirm pneumonia. We determined the PTX3 threshold in BAL fluid for pneumonia and compared it to other biomarkers.ResultsMicrobiologically confirmed pneumonia of bacterial (n =12), viral (n =4) or fungal (n =8) etiology was diagnosed in 24 patients (29%). PTX3 levels in BAL fluid predicted pneumonia with an area under the receiving operator curve of 0.815 (95% CI =0.710 to 0.921, P <0.0001), whereas none of the other biomarkers were effective. In particular, PTX3 levels ≥1 ng/ml in BAL fluid predicted pneumonia in univariate analysis (β =2.784, SE =0.792, P <0.001) with elevated sensitivity (92%), specificity (60%) and negative predictive value (95%). Net reclassification index PTX3 values ≥1 ng/ml in BAL fluid for pneumonia indicated gain in sensitivity and/or specificity vs. all other mediators. These results did not change when we limited our analyses only to confirmed cases of bacterial pneumonia. Moreover, when we considered only the 70 patients who fulfilled the clinical criteria for the diagnosis of pneumonia at BAL fluid sampling, the diagnostic accuracy of PTX levels was confirmed in univariate and ROC curve analysis.ConclusionsIn this hypothesis-generating convenience sample, a PTX3 level ≥1 ng/ml in BAL fluid was discriminative of microbiologically confirmed pneumonia in mechanically ventilated patients.

Use of extracorporeal respiratory support during pregnancy: a case report and literature review

We describe the case of a 25 year-old woman at 27 weeks of gestation who was admitted to our intensive care unit (ICU) for acute respiratory distress syndrome (ARDS) caused by pandemic 2009 H1N1 influenza A. She presented with septic shock and refractory hypoxemia unresponsive to rescue therapies such as recruitment maneuvers, prone positioning, and nitric oxide inhalation. Extracorporeal membrane oxygenation (ECMO) for respiratory support was instituted, and the patients clinical conditions progressively improved: she was extubated after 16 days and discharged from the ICU 3 days later. No fetal complications were observed. At 38 weeks of gestation she gave birth to a healthy baby.

Nosocomial Infections During Extracorporeal Membrane Oxygenation: Incidence, Etiology, and Impact on Patients’ Outcome

Objective: To study incidence, type, etiology, risk factors, and impact on outcome of nosocomial infections during extracorporeal membrane oxygenation. Design: Retrospective analysis of prospectively collected data. Setting: Italian tertiary referral center medical-surgical ICU. Patients: One hundred five consecutive patients who were treated with extracorporeal membrane oxygenation from January 2010 to November 2015. Interventions: None. Measurements and Main Results: Ninety-two patients were included in the analysis (48.5 [37–56] years old, simplified acute physiology score II 37 [32–47]) who underwent peripheral extracorporeal membrane oxygenation (87% veno-venous) for medical indications (78% acute respiratory distress syndrome). Fifty-two patients (55%) were infected (50.4 infections/1,000 person-days of extracorporeal membrane oxygenation). We identified 32 ventilator-associated pneumonia, eight urinary tract infections, five blood stream infections, three catheter-related blood stream infections, two colitis, one extracorporeal membrane oxygenation cannula infection, and one pulmonary-catheter infection. G+ infections (35%) occurred earlier compared with G– (48%) (4 [2–10] vs. 13 [7–23] days from extracorporeal membrane oxygenation initiation; p < 0.001). Multidrug-resistant organisms caused 56% of bacterial infections. Younger age (2–35 years old) was independently associated with higher risk for nosocomial infections. Twenty-nine patients (31.5%) died (13.0 deaths/1,000 person-days of extracorporeal membrane oxygenation). Infected patients had higher risk for death (18 vs. 8 deaths/1,000 person-days of extracorporeal membrane oxygenation; p = 0.037) and longer ICU stay (32.5 [19.5–78] vs. 19 [10.5–27.5] days; p = 0.003), mechanical ventilation (36.5 [20–80.5] vs. 16.5 [9–25.5] days; p < 0.001), and extracorporeal membrane oxygenation (25.5 [10.75–54] vs. 10 [5–13] days; p < 0.001). Older age (> 50 years old), reason for connection different from acute respiratory distress syndrome, higher simplified acute physiology score II, diagnosis of ventilator-associated pneumonia, and infection by multidrug-resistant bacteria were independently associated to increased death rate. Conclusions: Infections (especially ventilator-associated pneumonia) during extracorporeal membrane oxygenation therapy are common and frequently involve multidrug-resistant organisms. In addition, they have a negative impact on patients’ outcomes.

A mathematical model of oxygenation during venovenous extracorporeal membrane oxygenation support

PURPOSE To develop a mathematical model of oxygenation during venovenous extracorporeal membrane oxygenation (vv-ECMO). MATERIAL AND METHODS Total oxygen consumption, cardiac output, blood flow, recirculation, intrapulmonary shunt, hemoglobin, natural lung, and membrane lung oxygen fractions were chosen as inputs. Content, partial pressure, and hemoglobin saturation of oxygen in arterial, venous, pulmonary, and extracorporeal blood were outputs. To assess accuracy and predictive power of the model, we retrospectively analyzed data of 25 vv-ECMO patients. We compiled 2 software (with numerical, 2D and 3D graphical outputs) to study the impact of each variable on oxygenation. RESULTS The model showed high accuracy and predictive power. Raising blood flow and oxygen fraction to the membrane lung or reducing total oxygen consumption improves arterial and venous oxygenation, especially in severe cases; raising oxygen fraction to the natural lung improves oxygenation only in milder cases; raising hemoglobin always improves oxygenation, especially in the venous district; recirculation fraction severely impairs oxygenation. In severely ill patients, increasing cardiac output worsens arterial oxygenation but enhances venous oxygenation. Oxygen saturation of ECMO inlet is critical to evaluate the appropriateness of oxygen delivery. CONCLUSIONS The model with the software can be a useful teaching tool and a valuable decision-making aid for the management of hypoxic patients supported by vv-ECMO.

Percutaneous Cannulation: Indication, Technique, and Complications

Vascular access to systemic circulation is the key point for ECMO institution. In the pioneering years, the surgical approach was the rule both for central and peripheral cannulation in V-A or V-V ECMO. In the early 1990s, the availability of new thin-walled spring-wired reinforced cannulas opened the era of percutaneous cannulation technique, which shortly became the first choice for ECMO peripheral cannulation. Benefits of percutaneous cannulation versus the surgical technique are a reduced procedural time, decreased bleeding complications, and easy decannulation without the need of vessel repair. Percutaneous placement of cannulas can be done at any bedside in the hospital, intensive care unit, emergency room, and catheterization laboratory or intraoperatively. We will review cannula implantation and explantation techniques for V-V and V-A ECMO and discuss the vascular complications that can ensue during and after the procedure and their possible solutions.

Bronchopleural Fistulae and Pulmonary Ossification in Posttraumatic Acute Respiratory Distress Syndrome: Successful Treatment With Extracorporeal Support

We report a case of severe posttraumatic acute respiratory distress syndrome (ARDS) complicated by bronchopleural fistulae (BPF). The stiff ARDS lung and huge air leaks from BPF resulted in the failure of different protective mechanical ventilation strategies to provide viable gas exchange. Lung rest, achieved by extracorporeal carbon dioxide removal (ECCO₂R), allowed weaning from mechanical ventilation, closure of BPF, and resumption of spontaneous breathing.