Open Lung Research Articles

To the possibility of detecting the "coronary theft" syndrome in small laboratory animals

The purpose of the study. There are investigation of the possibility of using the laser Doppler flowmetry method to assess blood microcirculation and analyze the mechanisms of its regulation in conditionally intact and ischemic myocardium in small laboratory animals (rats) to identify the "coronary theft" syndrome. Materials and methods. The experiments were carried out on white mongrel anesthetized (urethane 1300 mg/kg /b) male rats weighing 200-250 g. 28 days after the reproduction of an experimental myocardial infarction in an open chest and artificial lung ventilation, the microcirculation level was assessed in conditionally intact and ischemic areas of the myocardium by laser Doppler flowmetry. Using spectral wavelet analysis, the amplitudes of microcirculation oscillations normalized to the total perfusion associated with various regulation mechanisms were determined. Results. It was found that the microcirculation level is significantly lower in the ischemic zone of the myocardium compared with the conditionally intact one (17.3±2.8 and 30.3±1.3 per. units, respectively, p = 0.006, n = 8). Spectral wavelet analysis showed that in the ischemic injury zone, in comparison with the conditionally intact myocardium, the amplitudes of microcirculation oscillations normalized to the general level of microcirculation increase for all regulatory mechanisms. Conclusion. The laser Doppler flowmetry method can be used to assess the intensity of microcirculation in conditionally intact and ischemic myocardium. Using this method makes it possible to identify the "coronary theft" syndrome in experiments on small experimental animals.

Impact on Health-Related Quality of Life of Video-Assisted Thoracoscopic Surgery for Lung Cancer

BackgroundVideo-assisted thoracoscopic surgery (VATS) approaches are increasingly used in lung cancer surgery, but little is known about their impact on patients’ health-related quality of life (HRQL). This prospective study measured recovery and HRQL in the year after VATS for non-small cell lung cancer (NSCLC) and explored the feasibility of HRQL data collection in patients undergoing VATS or open lung resection.Patients and MethodsConsecutive patients referred for surgical assessment (VATS or open surgery) for proven/suspected NSCLC completed HRQL and fatigue assessments before and 1, 3, 6 and 12 months post-surgery. Mean HRQL scores were calculated for patients who underwent VATS (segmental, wedge or lobectomy resection). Paired t-tests compared mean HRQL between baseline and expected worst (1 month), early (3 months) and longer-term (12 months) recovery time points.ResultsA total of 92 patients received VATS, and 18 open surgery. Questionnaire response rates were high (pre-surgery 96–100%; follow-up 67–85%). Pre-surgery, VATS patients reported mostly high (good) functional health scores [(European Organisation for Research and Treatment of Cancer) EORTC function scores > 80] and low (mild) symptom scores (EORTC symptom scores < 20). One-month post-surgery, patients reported clinically and statistically significant deterioration in overall health and physical, role and social function (19–36 points), and increased fatigue, pain, dyspnoea, appetite loss and constipation [EORTC 12–26; multidimensional fatigue inventory (MFI-20) 3–5]. HRQL had not fully recovered 12 months post-surgery, with reduced physical, role and social function (10–14) and persistent fatigue and dyspnoea (EORTC 12–22; MFI-20 2.7–3.2).ConclusionsLung resection has a considerable detrimental impact on patients’ HRQL that is not fully resolved 12 months post-surgery, despite a VATS approach.Graphic

Positive End-expiratory Pressure and Postoperative Atelectasis

Positive end-expiratory pressure (PEEP) increases lung volume and protects against alveolar collapse during anesthesia. During emergence, safety preoxygenation preparatory to extubation makes the lung susceptible to gas absorption and alveolar collapse, especially in dependent regions being kept open by PEEP. We hypothesized that withdrawing PEEP before starting emergence preoxygenation would limit postoperative atelectasis formation. This was a randomized controlled evaluator-blinded trial in 30 healthy patients undergoing nonabdominal surgery under general anesthesia and mechanical ventilation with PEEP 7 or 9 cm H2O depending on body mass index. A computed tomography scan at the end of surgery assessed baseline atelectasis. The study subjects were thereafter allocated to either maintained PEEP (n = 16) or zero PEEP (n = 14) during emergence preoxygenation. The primary outcome was change in atelectasis area as evaluated by a second computed tomography scan 30 min after extubation. Oxygenation was assessed by arterial blood gases. Baseline atelectasis was small and increased modestly during awakening, with no statistically significant difference between groups. With PEEP applied during awakening, the increase in atelectasis area was median (range) 1.6 (-1.1 to 12.3) cm and without PEEP 2.3 (-1.6 to 7.8) cm. The difference was 0.7 cm (95% CI, -0.8 to 2.9 cm; P = 0.400). Postoperative atelectasis for all patients was median 5.2 cm (95% CI, 4.3 to 5.7 cm), corresponding to median 2.5% of the total lung area (95% CI, 2.0 to 3.0%). Postoperative oxygenation was unchanged in both groups when compared to oxygenation in the preoperative awake state. Withdrawing PEEP before emergence preoxygenation does not reduce atelectasis formation after nonabdominal surgery. Despite using 100% oxygen during awakening, postoperative atelectasis is small and does not affect oxygenation, possibly conditional on an open lung during anesthesia, as achieved by intraoperative PEEP.

Conditional Hemodynamic Tolerance to Decremental Recruitment of the "Open Lung".

Conditional Hemodynamic Tolerance to Decremental Recruitment of the "Open Lung".

CHRONIC PARENCHYMAL INFILTRATION FROM MALT LYMPHOMA: DIAGNOSIS BY ENDOBRONCHIAL ULTRASOUND

SESSION TITLE: Lung Pathology 2 SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: 10/09/2018 01:15 PM - 02:15 PM INTRODUCTION: Mucosa-associated lymphoid tissue (MALT) lymphoma is a rare cause of pulmonary infiltrate. The lung accounts for only 4% of all extra-nodal marginal zone MALT lymphomas [1] and presents mostly as an incidental finding or with non-specific symptoms. CASE PRESENTATION: A previously healthy 59-year-old man presented with chest pain in 2013. A chest radiograph noted bilateral infrahiliar masses. Computed tomography (CT) of the chest showed bilateral lung consolidations (Figure 1). He was treated with antibiotics and lost to follow up. Five years later the patient presented with transient stroke-like symptoms and a chest x-ray showed a persistent infiltrate. CT chest noted large bibasilar consolidations with air bronchograms and dilated bronchi (Figure 2). These infiltrates were hypermetabolic on positron emission tomography (PET) with a maximum standardized uptake value (SUV) of 6.4. The patient underwent bronchoscopy with endobronchial ultrasound guided transbronchial 19 gauge needle aspiration (EBUS-TBNA) of the consolidative lesions. Immunohistochemistry and flow cytometry confirmed a diagnosis of MALT lymphoma. He was referred to oncology and initiated on rituximab and bendamustine. DISCUSSION: MALT lymphoma of the lung is a relatively rare disease that has been associated with chronic antigen stimulation in the context of infection, autoimmune disease and toxic exposure. The clinical presentation and radiographic findings are varied and can be mistaken for more common entities. Lesions are usually bilateral and often have associated air bronchograms and bronchiectasis [2]. The disease usually has an indolent course with a favorable prognosis. In most reported cases, diagnosis was achieved with open lung or CT-guided biopsy. The role of EBUS-TBNA for pulmonary MALT lymphoma has been previously described in mediastinal lymphadenopathy and was found to be useful [3]. To our knowledge, this is the first case of EBUS-TBNA of lung infiltrates to diagnose this condition. CONCLUSIONS: MALT lymphoma is a rare lung malignancy that should be considered in the differential diagnosis of non-resolving pulmonary lesions. Minimally invasive approaches such as bronchoscopy and EBUS-TBNA can retrieve sufficient tissue for diagnosis. Reference #1: Schreuder MI, Van den Brand M, Hebeda K, et al. Novel developments in the pathogenesis and diagnosis of extranodal marginal zone lymphoma. J Hemathopatol. 2017; 10: 91-107. Reference #2: Wislez M, Cadranel J, Antoine M, et al. Lymphoma of pulmonary mucosa-associated lymphoid tissue: CT scan findings and pathological correlations. Eur Respir J. 1999; 14: 423-429. Reference #3: Nunez AL, Jhala NC, Carroll AJ, et al. Endoscopic ultrasound and endobronchial ultrasound-guided fine-needle aspiration of deep-seated lymphadenopathy: Analysis of 1338 cases. Cytojournal. 2012;9:14. DISCLOSURES: Consultant relationship with Boston Scientific Please note: $1-$1000 Added 03/02/2018 by Alex Chee, source=Web Response, value=Consulting fee No relevant relationships by Isabel Londono Marulanda, source=Web Response Consultant relationship with Boston Scientific Please note: $5001 - $20000 Added 03/04/2018 by Adnan Majid, source=Web Response, value=Consulting fee Consultant relationship with Olympus Please note: $5001 - $20000 Added 03/04/2018 by Adnan Majid, source=Web Response, value=Consulting fee No relevant relationships by Mihir Parikh, source=Web Response No relevant relationships by Andrew Schissler, source=Web Response

The Effects of an Open-Lung Approach During One-Lung Ventilation on Postoperative Pulmonary Complications and Driving Pressure: A Descriptive, Multicenter National Study

Thoracic surgical procedures are associated with an increased risk of postoperative pulmonary complications (PPCs), which seem to be related directly to intraoperative driving pressure. The authors conducted this study to describe the incidence of PPCs in patients in whom an individualized open-lung approach was applied during one-lung ventilation. This was a prospective, multicenter, national descriptive study. Thoracic surgery patients undergoing one-lung ventilation. Eligible participants were included consecutively from October 1, 2016, to September 30, 2017. A total of 690 patients were included. An individualized open-lung approach that consisted of an alveolar recruitment maneuver followed by a positive end-expiratory pressure adjusted to best respiratory system compliance was performed in all patients. Preoperative and intraoperative data were recorded; the primary outcome was a description of the incidence of PPCs in these patients during the first 7 postoperative days. The patients were mainly male, and half of them had a high risk of PPCs (ARISCAT score exceeding 44). Eleven percent of participants developed a PPC within the first postoperative week. The mean open lung positive end-expiratory pressure was 8 ± 3 cmH2O. When compared with pre-open lung approach values, the open-lung approach significantly decreased the driving pressure (14±4 cmH2O v 11±3 cmH2O; p<0.001) and increased dynamic compliance (30±10 mL/cmH2O v 43 ±15 mL/cmH2O; p <0.001). The low incidence of PPCs in patients who underwent an open-lung approach during one-lung ventilation compared with that reported for other thoracic surgery series and the decrease in the driving pressure in these patients justify an additional randomized controlled trial to compare the open-lung approach with the standard protective strategy of low tidal volume and low positive end-expiratory pressure.

Individualised perioperative open-lung approach versus standard protective ventilation in abdominal surgery (iPROVE): a randomised controlled trial

The effects of individualised perioperative lung-protective ventilation (based on the open-lung approach [OLA]) on postoperative complications is unknown. We aimed to investigate the effects of intraoperative and postoperative ventilatory management in patients scheduled for abdominal surgery, compared with standard protective ventilation. We did this prospective, multicentre, randomised controlled trial in 21 teaching hospitals in Spain. We enrolled patients who were aged 18 years or older, were scheduled to have abdominal surgery with an expected time of longer than 2 h, had intermediate-to-high-risk of developing postoperative pulmonary complications, and who had a body-mass index less than 35 kg/m2. Patients were randomly assigned (1:1:1:1) online to receive one of four lung-protective ventilation strategies using low tidal volume plus positive end-expiratory pressure (PEEP): open-lung approach (OLA)-iCPAP (individualised intraoperative ventilation [individualised PEEP after a lung recruitment manoeuvre] plus individualised postoperative continuous positive airway pressure [CPAP]), OLA-CPAP (intraoperative individualised ventilation plus postoperative CPAP), STD-CPAP (standard intraoperative ventilation plus postoperative CPAP), or STD-O2 (standard intraoperative ventilation plus standard postoperative oxygen therapy). Patients were masked to treatment allocation. Investigators were not masked in the operating and postoperative rooms; after 24 h, data were given to a second investigator who was masked to allocations. The primary outcome was a composite of pulmonary and systemic complications during the first 7 postoperative days. We did the primary analysis using the modified intention-to-treat population. This trial is registered with ClinicalTrials.gov, number NCT02158923. Between Jan 2, 2015, and May 18, 2016, we enrolled 1012 eligible patients. Data were available for 967 patients, whom we included in the final analysis. Risk of pulmonary and systemic complications did not differ for patients in OLA-iCPAP (110 [46%] of 241, relative risk 0·89 [95% CI 0·74-1·07; p=0·25]), OLA-CPAP (111 [47%] of 238, 0·91 [0·76-1·09; p=0·35]), or STD-CPAP groups (118 [48%] of 244, 0·95 [0·80-1·14; p=0·65]) when compared with patients in the STD-O2 group (125 [51%] of 244). Intraoperatively, PEEP was increased in 69 (14%) of patients in the standard perioperative ventilation groups because of hypoxaemia, and no patients from either of the OLA groups required rescue manoeuvres. In patients who have major abdominal surgery, the different perioperative open lung approaches tested in this study did not reduce the risk of postoperative complications when compared with standard lung-protective mechanical ventilation. Instituto de Salud Carlos III of the Spanish Ministry of Economy and Competitiveness, and Grants Programme of the European Society of Anaesthesiology.

Robotic Versus Video-Assisted Thoracoscopic Lobectomy (VATS) for Lung Cancer

Purpose of Review Video-assisted thoracoscopic (VATS) lobectomy has been demonstrated to be a safe procedure, and it is known to provide less postoperative pain, similar lymph node dissection capabilities, decreased length of postoperative stay, less complications, reduced mortality, and similar oncologic outcomes compared with open lobectomy lung cancer operations.

Lung recruitment strategies

Mechanical ventilation in newborns, children and adults leads to lung injury and has been shown to induce the formation of proteinaceous lung oedema causing epithelial disruption and resulting in changes in lung perfusion. Lung injury leads to reduced compliance, worsening of shunt fraction and an inflammatory response that results from high end-inspiratory transpulmonary pressures (Ptp) and inadequate End Expiratory Lung Volume (EELV). Lung injury results if a lung is ventilated from collapsed state with each ventilator cycle. Thus the first concept of treatment in acute hypoxic respiratory failure is: “Open collapsed lung units and keep them open without overdistending them”. The open lung is one in which there is little or no atelectasis and an optimal gas exchange. Lung recruitment strategies transiently increase Ptp to reopen the alveolar units not aerated or poorly aerated but recruitable. Lung recruitment maneuvers may restore EELV resulting in more stable alveoli, and reduce shear stress associated with the alveolar cyclic opening and closing. Lung recruitment can be performed in several ways: in delivery room with a T-piece device, in the NICU setting by using a conventional or high frequency oscillation (HFO) ventilator, and is commonly achieved by increase of end-expiratory lung volume with positive end expiratory pressure (PEEP) or end inspiratory lung volume by inspiratory holds or sustained inflation. Recruitment during both, HFO and CMV (Conventional Mechanical Ventilation), follows similar concepts when using small tidal volume ventilation but is easier to achieve at bedside during HFO. The Sustained Inflation maneuver (SI) applies a high pressure to the lung for a short period (30 sec) before returning to previous mean airway pressures. This volume recruitment strategy has been shown to be as protective as high frequency oscillatory ventilation (HFO) at similar lung volumes. Infants treated with a SI in delivery room had improved short-term respiratory outcomes (reduced need of tracheal intubation and mechanical ventilation), but major outcomes (BPD Bronchopulmonary dysplasia- and/or death) were not improved. Recent reports describe improvements in arterial oxygenation with the use of recruitment maneuvers during CMV and/or HFO. However, the impact of these strategies on patient important outcomes such as survival is still unclear. Further clinical studies are needed to evaluate the efficacy of SI, including selection of patients, setting of SI maneuver in terms of duration and peak pressure, timing of surfactant administration. Further studies are also needed to elucidate the impact of recruitment maneuvers during mechanical ventilation, including survival and BPD.

Lung Recruitment in Trauma Patients

The ventilatory management of trauma patients can present significant challenges. Its main aims focus on the reduction of the work of breathing, facilitation of an improvement in gaseous exchange, and on the avoidance of ventilation-induced lung injury (VILI). VILI is a pathophysiologic process consisting of several changes seen in ventilated lungs that have been attributed to the ventilation strategy employed subsequent to the traumatic lung injury. In order to avoid the major components of VILI, both maximal alveolar aeration and recruitment are needed to minimize the shear stresses in the injured lung tissue. Alveolar recruitment maneuvers have become the major goals of mechanical ventilatory support for patients with severe trauma over the last few decades. The importance of early lung recruitment with an ‘open lung’ approach has been well documented in several studies and its application has been shown to preserve lung mechanics, attenuate lung mechanotrauma, and thereby reduce mortality during ventilation. Controversies nonetheless exist regarding the most appropriate form of their use in patients with pulmonary injuries as recruitment maneuvers may have several adverse effects. The main concerns center on exploiting high airway pressures during the recruitment process and its potential harmful consequences, such as barotrauma and hemodynamic compromise. The purpose of this article is to review the major concepts in the mechanical ventilation literature that outline the principles for the use of the open lung management strategy in patients that have been subjected to significant trauma and to delineate both the major techniques of lung recruitment as well as their potential complications. Correspondence to: Marcin Karcz, Department of Anesthesiology, University of Rochester Medical Center, 601 Elmwood Avenue, PO Box 604, Rochester, New York, 14642, USA, Tel: +1-585-275-1385; Fax: +1-585-244-727; E-mail: marcin_karcz@urmc.rochester.edu

Neonatal lung physiology and respiratory support of newborns

Article elucidates the neonatal lung physiology in newborns, methods of respiratory support, particularly positive pressure ventilation, and pulmonary changes caused by anesthesia and surgery. Optimal methods of respiratory support in preterm and full-term newborns are considered. It was noted that newborn infants have a high risk of respiratory complications during anesthesia which can be attributed to their respiratory physiology. The balance between volume of closing and functional residual capacity can be easily disrupted during anesthesia and surgery, which immediately leads to respiratory disorders. Therefore the strategy should include «open lung» ventilation conception and avoid high tidal volume and excessive oxygen inspiratory fraction. High-frequency oscillatory ventilation (HFOV) often used in babies with severe respiratory failure does not have the advantages in reducing of the BPD development, other pulmonary fatalities, as well as severe neurological complications in preterm infants comparing with conventional ventilation. Regarding full-term newborns, the timely start of HFOV may be more effective than conventional mechanical ventilation. This review also applies to such issues as use of inhaled nitric oxide, using of cuffed endotracheal tubes, the influence of anesthetics on immature lungs and breathing problems that may occur during anesthesia and surgery.

ABSTRACT 439

Background and aims: to prove scientifically and introduce into clinical practice the method of exogenous surfactant replacement therapy at the time of “mobilization of alveoli” in neonates and infants with ALI / ARDS, operated on different CHD. Methods: Central hemodynamics, X-rays of the lungs, gas exchange, ventilator parameters and mechanical properties of the lungs have been analyzed in 6 hours since the syndrome manifestation and also after the recruitment maneuver and the administration of exogenous surfactant. We also analyzed the duration of mechanical ventilation and the ICU period in 25 children aged from 24 days to 16 months (5,7 ± 4,8 m.). Surfactant was administered after the procedure of lung recruitment without the decompression circuit. Results: There was an increase from 135 paO2/FiO2 ± 38,0 to 329,6 ± 33,2 (p <0.05) in patients after the recruitment maneuver and the subsequent introduction of exogenous surfactant at the peak of the disclosure of alveoli. This allowed to reduce the intensity of ventilation modes downward Pmean with 12,4 ± 1,65 to 10,77 ± 2,66 mbar and with FiO2 0,76 ± 0,2 to 0,45 ± 0,06. One (4.16%) of the 25 patients died from the critical respiratory failure. Conclusions: Securing of ALI /ARDS targeted delivery of exogenous surfactant to the damaged alveoli at the first 24 hours since the beginning of manifestation with the concept of “the open lung”, leads to significant improvement and stabilization of the mechanical properties of the lungs and gas exchange, which enables to reduce aggressive ventilator settings.

Pulmonary Manifestations of Granulomatosis With Polyangiitis

ObjectiveTo describe the clinical and laboratory data, with special emphasis on thoracic imaging findings, in 14 patients with a definitive diagnosis of granulomatosis with polyangiitis (GPA). MethodsThe clinical and tomographic data of 14patients with a definitive diagnosis of GPA are presented. Patients with thoracic manifestations suggestive of GPA were evaluated in 3 hospitals from 2000 to 2012. All patients had a sputum analysis and bronchoalveolar lavage for bacterial, mycobacterial and fungal stains and cultures; antineutrophil cytoplasmic antibodies, antinuclear-antibodies, rheumatoid factor, and a biopsy of involved organs. ResultsA total of 13 patients had at least two organs involved. The most frequent thoracic findings were pulmonary nodules, ground glass opacities and patches of consolidation; other abnormalities were tracheal stenosis, diffuse alveolar hemorrhage, lung masses with organized pneumonia. More than three-quarters (78%) of patients had positive antineutrophil cytoplasmic antibodies (ANCA). Ten patients had respiratory tissue biopsy (8 open lung, one tracheal, and one nasal). In 4 patients the diagnosis was made with the classic organ involvement in GPA, positive ANCA, and renal or skin biopsy, and response to treatment on follow-up. At 6–12months all patients showed clinical and radiological improvement, with 54% showing a recurrence of disease. DiscussionThe majority of thoracic findings described in GPA are presented in this study. A complete diagnostic approach with invasive diagnostic procedures to rule out other more prevalent respiratory diseases with similar thoracic manifestations must be performed. The positivity of ANCA in this study was high, and the recurrence of the disease was frequent.

Manifestaciones pulmonares de la granulomatosis con poliangitis

ObjectiveTo describe the clinical and laboratory data, with special emphasis on thoracic imaging findings, in 14patients with a definitive diagnosis of granulomatosis with polyangiitis (GPA). MethodsThe clinical and tomographic data of 14patients with a definitive diagnosis of GPA are presented. Patients with thoracic manifestations suggestive of GPA were evaluated in 3hospitals from 2000 to 2012. All patients had a sputum analysis and bronchoalveolar lavage for bacterial, mycobacterial and fungal stains and cultures; antineutrophil cytoplasmic antibodies, antinuclear-antibodies, rheumatoid factor, and a biopsy of involved organs. ResultsA total of 13patients had at least two organs involved. The most frequent thoracic findings were pulmonary nodules, ground glass opacities and patches of consolidation; other abnormalities were tracheal stenosis, diffuse alveolar hemorrhage, lung masses with organized pneumonia. More than three-quarters (78%) of patients had positive antineutrophil cytoplasmic antibodies (ANCA). Ten patients had respiratory tissue biopsy (8 open lung, one tracheal, and one nasal). In 4patients the diagnosis was made with the classic organ involvement in GPA, positive ANCA, and renal or skin biopsy, and response to treatment on follow-up. At 6-12months all patients showed clinical and radiological improvement, with 54% showing a recurrence of disease. DiscussionThe majority of thoracic findings described in GPA are presented in this study. A complete diagnostic approach with invasive diagnostic procedures to rule out other more prevalent respiratory diseases with similar thoracic manifestations must be performed. The positivity of ANCA in this study was high, and the recurrence of the disease was frequent.

Initial commitment for inhalation injury

26. Mehta S, Lapinsky SE, Hallett DC, et al. Prospective trial of high‐frequency oscillation in adults with acute respiratory distress syndrome. Crit Care Med. 2001;29(7):1360–1369. 27. Wrigge H, Zinserling J, Neumann P, et al. Spontaneous breathing with airway pressure release ventilation favors ventilation in dependent lung regions and counters cyclic alveolar collapse in oleic‐acidinduced lung injury: a randomized controlled computed tomography trial. Crit Care. 2005;9(6):R780–R789. 28. Yoshida T, Rinka H, Kaji A, et al. The impact of spontaneous ventilation on distribution of lung aeration in patients with acute respiratory distress syndrome: airway pressure release ventilation versus pressure support ventilation. Anesth Analg. 2009;109(6):1892–1900. 29. Putensen C, Zech S, Wrigge H, et al. Longterm effects of spontaneous breathing during ventilatory support in patients with acute lung injury. Am J Respir Crit Care Med. 2001;164(1):43–49. 30. Albert S, Kubiak BD, Vieau CJ, et al. Comparison of “open lung”modes with low tidal volumes in a porcine lung injury model. J Surg Res. 2011;166(1):e71–e81. 31. Walkey AJ, Nair S, Papadopoulos S, Agarwal S, Reardon CC. Use of airway pressure release ventilation is associated with a reduced incidence of ventilatorassociated pneumonia in patients with pulmonary contusion. J Trauma Acute Care Surg. 2011;70(3):E42–E47. 32. Maung AA, Luckianow G, Kaplan LJ. Lessons learned from airway pressure release ventilation. J Trauma Acute Care Surg. 2012;72(3):624–628. 33. Hanna K, Seder CW, Weinberger JB, Sills PA, Hagan M, Janczyk RJ. Airway pressure release ventilation and successful lung donation. Arch Surg. 2011;146(3):325–328.

Update on Mechanical Ventilatory Strategies

Mechanical ventilation is essential for survival of many extremely premature infants, but all forms of positive pressure ventilation are to some degree injurious to the lungs. A variety of sophisticated devices are used to provide respiratory support, yet substantial uncertainty remains regarding the optimal ways in which these tools can be used to minimize ventilator-associated lung injury. A good understanding of the unique aspects of respiratory physiology of extremely preterm infants is key to obtaining the greatest benefit from modern ventilator technology. Early lung volume recruitment with adequate end-expiratory pressure, avoidance of volutrauma during the immediate postnatal period, and noninvasive respiratory support as the initial strategy are now accepted as important factors in minimizing lung injury. Volume-targeted ventilation combined with optimal lung volume strategies to ensure that the tidal volume is evenly distributed throughout an open lung seems to be the best approach to lower the incidence of bronchopulmonary dysplasia.

Airway Pressure Release Ventilation in Morbidly Obese Surgical Patients with Acute Lung Injury and Acute Respiratory Distress Syndrome

Morbidly obese patients with body mass index greater than 40 kg/m(2) and respiratory failure requiring critical care services are increasingly seen in trauma and acute care surgical centers. Baseline respiratory pathophysiology including decreased pulmonary compliance with dependent atelectasis and abnormal ventilation-perfusion relationships predisposes these patients to acute lung injury (ALI) and adult respiratory distress syndrome (ARDS) as well as prolonged stays in the intensive care unit. Airway pressure release ventilation (APRV) is an increasingly used alternative mode for salvage therapy in patients with hypoxemic respiratory failure that also provides lung protection from ventilator-induced lung injury. APRV provides the conceptual advantage of an "open lung" approach to ventilation that may be extended to the morbidly obese patient population with ALI and ARDS. We discuss the theoretical benefits and a recent clinical experience of APRV ventilation in the morbidly obese patient with respiratory failure at a Level I trauma, surgical critical care, and acute care surgery center.

The effect of averaging adjacent planes for artifact reduction in matrix inversion tomosynthesis

Matrix inversion tomosynthesis (MITS) uses linear systems theory and knowledge of the imaging geometry to remove tomographic blur that is present in conventional backprojection tomosynthesis reconstructions, leaving in-plane detail rendered clearly. The use of partial-pixel interpolation during the backprojection process introduces imprecision in the MITS modeling of tomographic blur, and creates low-contrast artifacts in some MITS planes. This paper examines the use of MITS slabs, created by averaging several adjacent MITS planes, as a method for suppressing partial-pixel artifacts. Human chest tomosynthesis projection data, acquired as part of an IRB-approved pilot study, were used to generate MITS planes, three-plane MITS slabs (MITSa3), five-plane MITS slabs (MITSa5), and seven-plane MITS slabs (MITSa7). These were qualitatively examined for partial-pixel artifacts and the visibility of normal and abnormal anatomy. Additionally, small (5 mm) subtle pulmonary nodules were simulated and digitally superimposed upon human chest tomosynthesis projection images, and their visibility was qualitatively assessed in the different reconstruction techniques. Simulated images of a thin wire were used to generate modulation transfer function (MTF) and slice-sensitivity profile curves for the different MITS and MITS slab techniques, and these were examined for indications of partial-pixel artifacts and frequency response uniformity. Finally, mean-subtracted, exposure-normalized noise power spectra (ENNPS) estimates were computed and compared for MITS and MITS slab reconstructions, generated from 10 sets of tomosynthesis projection data of an acrylic slab. The simulated in-plane MTF response of each technique was also combined with the square root of the ENNPS estimate to yield stochastic signal-to-noise ratio (SNR) information about the different reconstruction techniques. For scan angles of 20° and 5 mm plane separation, seven MITS planes must be averaged to sufficiently remove partial-pixel artifacts. MITSa7 does appear to subtly reduce the contrast of high-frequency "edge" information, but the removal of partial-pixel artifacts makes the appearance of low-contrast, fine-detail anatomy even more conspicuous in MITSa7 slices. MITSa7 also appears to render simulated subtle 5 mm pulmonary nodules with greater visibility than MITS alone, in both the open lung and regions overlying the mediastinum. Finally, the MITSa7 technique reduces stochastic image variance, though the in-plane stochastic SNR (for very thin objects which do not span multiple MITS planes) is only improved at spatial frequencies between 0.05 and 0.20 cycles∕mm. The MITSa7 method is an improvement over traditional single-plane MITS for thoracic imaging and the pulmonary nodule detection task, and thus the authors plan to use the MITSa7 approach for all future MITS research at the authors' institution.

Atelectasis and perioperative pulmonary complications in high-risk patients

This review evaluates the link between perioperative lung atelectasis and postoperative pulmonary complications (PPCs) and how appropriate ventilatory strategies could mitigate this problem. Atelectasis may contribute to serious PPCs including respiratory failure and pneumonia. Ventilator settings during anesthesia, especially with higher tidal volumes (V(T)) (>10 ml/kg), high plateau pressures (>30 cmH(2)O) and without positive end expiratory pressure (PEEP), are associated with lung injury even in healthy, but partially collapsed, lungs. These injurious settings may cause inflammation which is related to repetitive tidal recruitment and alveolar overdistension. Such ventilator-induced lung injury can be attenuated by using low V(T) and plateau pressures at sufficient PEEP, ideally after actively recruiting the lungs. The use of continuous positive airway pressure and 'lower' FiO(2) during anesthetic induction, intraoperative use of lower FiO(2), low V(T), lung recruitment and PEEP ('protective ventilatory strategy') in conjunction with postoperative early mobilization, breathing exercises and continuous positive airway pressure may help in maintaining lung aeration, thereby decreasing hypoxemia and risk of postoperative pneumonia. Evidence is accumulating suggesting that the incidence of postoperative pulmonary complication could be markedly reduced if an 'open lung' philosophy was adopted for the perioperative care. A goal-directed ventilatory approach keeping an 'open lung' condition during the perioperative period may reduce the incidence of PPCs.

Profil étiologique et épidémiologique des granulomatoses systémique dans un service de médecine interne

Although maintaining some amount of positive end-expiratory pressure (PEEP) seems essential, selecting and titrating a specific level for patients with ARDS remains challenging despite extensive research on the subject. Although an “open lung” approach to ventilation is popular and has some degree of biological plausibility, it is not without risk. Furthermore, there is no clear evidence-based guidance regarding initial PEEP settings or how to titrate them early in the course of the illness. Many busy clinicians use a “one-size-fits-all” approach based on local medical culture, but an individualized approach has the potential to offer significant benefit. Here we present a pragmatic approach based on simple measurements available on all ventilators, focused on achieving balance between the potential risks and benefits of PEEP. Acknowledging “best PEEP” as an impossible goal, we aim for a straightforward method to achieve “better PEEP.”