Improved Lung Compliance Research Articles

Safety and effectiveness of alveolar recruitment maneuvers and positive end-expiratory pressure during general anesthesia for cesarean section: a prospective, randomized trial

IntroductionDuring cesarean section, the supine position reduces functional residual capacity and worsens lung compliance. We tested the hypothesis that alveolar recruitment maneuvers and positive end-expiratory pressure improve lung compliance in women undergoing general anesthesia for cesarean section. MethodsNinety women undergoing cesarean section were randomly assigned to one of two groups in a prospective, double-blind trial. In the alveolar recruitment maneuver group, pressure-control ventilation was used and inspiratory time was increased to 50% after delivery; positive end-expiratory pressure was increased to 20cmH2O and peak airway inspiratory pressure gradually increased to 45–50cmH2O. Volume-control ventilation was then used with low tidal volumes (6mL/kg) and positive end-expiratory pressure was reduced stepwise to 8cmH2O. In the control group, alveolar recruitment maneuvers were not used. Data were collected before and 3, 10 and 20min after the alveolar recruitment maneuver, before extubation and postoperatively at 10 and 20min. ResultsDynamic compliance, peak airway inspiratory pressure, PaO2 and PaO2/FiO2 were significantly different in the alveolar recruitment maneuver group compared to controls at all time points during surgery except at baseline. Oxygen saturation was significantly greater in the alveolar recruitment maneuver group at 10 and 20min and before extubation. Dynamic compliance was 29.7–42.5% higher and peak airway inspiratory pressure 3.6–10.2% lower in the alveolar recruitment maneuver group compared to controls. The PaO2, PaO2/FiO2 and oxygen saturation were higher (9.4–12%, 10.3–11.9% and 0.4–1.3%, respectively) in the alveolar recruitment maneuver group. Postoperatively, PaO2 and oxygen saturation were significantly higher in the alveolar recruitment maneuver group compared to controls (PaO2 9.2% at 10min and 8.4% at 20min, oxygen saturation 0.8% at 10min and 1.1% at 20min). There were no significant differences in hemodynamic stability or adverse events between groups. ConclusionCompared to standard care, the alveolar recruitment maneuver with positive end-expiratory pressure and low tidal volumes appears safe and effective in improving lung compliance and both intraoperative and postoperative oxygenation in women undergoing general anesthesia for elective cesarean section.

Protein Kinase Cζ Inhibitor Promotes Resolution of Bleomycin-Induced Acute Lung Injury.

Protein kinase Cζ (PKCζ) is highly expressed in the lung, where it plays several regulating roles in the pathogenesis of acute lung injury (ALI). Proliferation and differentiation of integrin β4+ distal lung epithelial progenitor cells seem to play a key role in proper lung regeneration. We investigated the effects of a myristoylated PKCζ inhibitor (PKCζi) in a murine model of bleomycin-induced ALI. After intratracheal injury, we treated mice three times a week with PKCζi or its vehicle, DMSO. We found that mice injured with bleomycin and then treated with PKCζi for one week showed decreased activation of PKCζ, improved lung compliance, and decreased lung protein permeability compared to injured mice treated with DMSO. Mice treated continuously with PKCζi for 6 weeks showed reduced evidence of lung fibrosis by computed tomographic images, decreased lung collagen deposition, and decreased active transforming growth factor-β in the bronchoalveolar lavage fluid. In addition, we found an increased number of lung β4+ cells compared to DMSO at Week 6. Therefore, we grew isolated integrin β4+ lung progenitor cells in the presence of PKCζi or DMSO and found that β4+ cells treated with PKCζi proliferated more in vitro compared to DMSO. We conclude that the use of a PKCζi promotes resolution of lung fibrosis in a bleomycin ALI model and increases the number of β4+ progenitor cells with regenerative potential in the lung.

Antenatal dexamethasone vs. betamethasone dosing for lung maturation in fetal sheep.

Dexamethasone-phosphate (Dex-PO4) and the combination betamethasone-phosphate (Beta-PO4) + betamethasone-acetate (Beta-Ac) are the most used antenatal corticosteroids to promote fetal lung maturation. We compared fetal lung maturation induced by Beta-Ac+Beta-PO4, Dex-PO4, or Beta-PO4 alone. Pregnant ewes received two intramuscular doses 24 h apart of 0.25 mg/kg/dose of Beta-Ac+Beta-PO4, Dex-PO4 or Beta-PO4; or 2 doses of 0.125 mg/kg/dose of Beta-PO4 at 6, 12, or 24 h intervals. Fetuses were delivered 48 h after the first dose and ventilated for 30 min. We assessed ventilatory variables, vital signs, and blood gas. After ventilation pressure-volume curves were measured and lungs were sampled for analysis. All treatments improved lung compliance and ventilation efficiency. Only Beta-Ac + Beta-PO4 required lower positive inspiratory pressure compared with control. Beta-Ac + Beta-PO4 and Beta-PO4 alone, but not Dex-PO4, increased the mRNA of surfactant proteins compared with control. Low-dose Beta-PO4 did not increase mRNA of surfactant proteins. There were no differences among Beta-PO4 treatment intervals. Beta-Ac + Beta-PO4 given as two doses 24 h apart was more effective in promoting fetal lung maturation than Dex-PO4 or Beta-PO4 alone, consistent with a prolonged exposure provided by the Beta-Ac + Beta-PO4. These results support the clinical use of combined Beta-Ac + Beta-PO4 preparations over phosphate corticosteroids alone for fetal lung maturation.

Comparing the Effect of Adaptive Support Ventilation (ASV) and Synchronized Intermittent Mandatory Ventilation (SIMV) on Respiratory Parameters in Neurosurgical ICU Patients.

BackgroundVarious modes of mechanical ventilation have different effects on respiratory variables. Lack of patients’ neuro-ventilatory coordination and increasing the work of breathing are major disadvantages in mechanically ventilated patients.ObjectivesThis study is conducted to compare the respiratory parameters differences in Adaptive support ventilation (ASV) and synchronized intermittent mandatory ventilation (SIMV) modes in neurosurgical ICU patients.MethodsIn a crossover study, patients under mechanical ventilation in neurosurgical ICU were enrolled. The patients alternatively experienced two types of ventilations for 30 minutes (adaptive support ventilation and synchronized intermittent mandatory ventilation). The respiratory parameters (tidal volume, respiratory rate, airway pressure, lung compliance, end-tidal carbon dioxide, peripheral oxygenation and respiratory dead space), hemodynamic variables, every 10 minutes and arterial blood gas analysis at the end of each 30 minutes were recorded. Results were compared and analyzed with SPSS v.19.ResultsSixty patients were involved in this study. In ASV mode, values including peak airway pressure (P-peak), end-tidal carbon dioxide (EtCO2), tidal volume and respiratory dead space were significantly lower than SIMV mode. Although the mean value for dynamic compliance had no significant difference in the two types of ventilation, it was better in ASV mode.ConclusionsASV mode compared with SIMV mode can lead to improve lung compliance and respiratory dead space.

Intratracheal Administration of Small Interfering RNA Targeting Fas Reduces Lung Ischemia-Reperfusion Injury.

Lung ischemia-reperfusion injury is the main cause of primary graft dysfunction after lung transplantation and results in increased morbidity and mortality. Fas-mediated apoptosis is one of the pathologic mechanisms involved in the development of ischemia-reperfusion injury. We hypothesized that the inhibition of Fas gene expression in lungs by intratracheal administration of small interfering RNA could reduce lung ischemia-reperfusion injury in an ex vivo model reproducing the procedural sequence of lung transplantation. Prospective, randomized, controlled experimental study. University research laboratory. C57/BL6 mice weighing 28-30 g. Ischemia-reperfusion injury was induced in lungs isolated from mice, 48 hours after treatment with intratracheal small interfering RNA targeting Fas, control small interfering RNA, or vehicle. Isolated lungs were exposed to 6 hours of cold ischemia (4°C), followed by 2 hours of warm (37°C) reperfusion with a solution containing 10% of fresh whole blood and mechanical ventilation with constant low driving pressure. Fas gene expression was significantly silenced at the level of messenger RNA and protein after ischemia-reperfusion in lungs treated with small interfering RNA targeting Fas compared with lungs treated with control small interfering RNA or vehicle. Silencing of Fas gene expression resulted in reduced edema formation (bronchoalveolar lavage protein concentration and lung histology) and improvement in lung compliance. These effects were associated with a significant reduction of pulmonary cell apoptosis of lungs treated with small interfering RNA targeting Fas, which did not affect cytokine release and neutrophil infiltration. Fas expression silencing in the lung by small interfering RNA is effective against ischemia-reperfusion injury. This approach represents a potential innovative strategy of organ preservation before lung transplantation.

Safety and Efficacy of Thoracostomy in the Air Medical Environment

ObjectiveThe use of thoracostomy to treat tension pneumothorax is a core skill for prehospital providers. Tension pneumothoraces are potentially lethal and are often encountered in the prehospital environment. MethodsThe authors reviewed the prehospital electronic medical records of patients who had undergone finger thoracostomy (FT) or tube thoracostomy (TT) while under the care of air medical crewmembers. Demographic data were obtained along with survival and complications. ResultsDuring the 90-month data period, 250 patients (18 years of age or older) underwent FT/TT, with a total of 421 procedures performed. The mean age of patients was 44.8 years, with 78.4% being male and 21.6% being female; 98.4% of patients had traumatic injuries. Cardiopulmonary resuscitation was required in 65.2% of patients undergoing FT/TT; 34.8% did not require cardiopulmonary resuscitation. Thirty percent of patients exhibited clinical improvement such as increasing systolic blood pressure, oxygen saturation, improved lung compliance, or a release of blood or air under tension. Patients who experienced complications such as tube dislodgement or empyema made up 3.4% of the cohort. ConclusionThe results of this study suggest that flight crews can use FT/TT in their practice on patients with actual or potential pneumothoraces with limited complications and generate clinical improvement in a subset of patients.

Spatiotemporal Aeration and Lung Injury Patterns Are Influenced by the First Inflation Strategy at Birth.

Ineffective aeration during the first inflations at birth creates regional aeration and ventilation defects, initiating injurious pathways. This study aimed to compare a sustained first inflation at birth or dynamic end-expiratory supported recruitment during tidal inflations against ventilation without intentional recruitment on gas exchange, lung mechanics, spatiotemporal regional aeration and tidal ventilation, and regional lung injury in preterm lambs. Lambs (127 ± 2 d gestation), instrumented at birth, were ventilated for 60 minutes from birth with either lung-protective positive pressure ventilation (control) or as per control after either an initial 30 seconds of 40 cm H2O sustained inflation (SI) or an initial stepwise end-expiratory pressure recruitment maneuver during tidal inflations (duration 180 s; open lung ventilation [OLV]). At study completion, molecular markers of lung injury were analyzed. The initial use of an OLV maneuver, but not SI, at birth resulted in improved lung compliance, oxygenation, end-expiratory lung volume, and reduced ventilatory needs compared with control, persisting throughout the study. These changes were due to more uniform inter- and intrasubject gravity-dependent spatiotemporal patterns of aeration (measured using electrical impedance tomography). Spatial distribution of tidal ventilation was more stable after either recruitment maneuver. All strategies caused regional lung injury patterns that mirrored associated regional volume states. Irrespective of strategy, spatiotemporal volume loss was consistently associated with up-regulation of early growth response-1 expression. Our results show that mechanical and molecular consequences of lung aeration at birth are not simply related to rapidity of fluid clearance; they are also related to spatiotemporal pressure-volume interactions within the lung during inflation and deflation.

Intraoperative pulmonary function dynamics in adolescents undergoing reduction mammoplasty: A prospective case series

Background Improvement of lung function following reduction mammoplasty has been previously reported among adult populations in the medical literature. Objectives To evaluate the intraoperative dynamics of pulmonary function in adolescents undergoing reduction mammoplasty. Methods The present study is a prospective case series of female patients 13 to 18 years of age who underwent inferior pedicle reduction mammoplasty between November 20, 2006 and April 4, 2011. Documented variables included patient baseline characteristics, operation duration, muscle relaxant use and total breast tissue removed. Intraoperative pulmonary function data documented included: tidal volume, respiratory rate, peak inspiratory pressure, positive end-expiratory pressure, oxygen saturation percentage and pulmonary compliance. Differences in pulmonary function data were calculated as ratio between final and initial intraoperative values. Results Twenty-six patients were included in the analysis. Mean (± SD) age was 16.9±1.1 years and mean body mass index was 28.9±6.1 kg/m2. Mean operation time was 218±52 min, with average total bilateral breast tissue removal of 1810±1065 g. Improvement in lung compliance was observed in 24 patients (92.3%; P<0.0001). Mean intraoperative lung compliance improvement was 23.92% (95% CI 8.3% to 37%; P=0.001). Conclusion Intraoperative improvement in lung compliance was observed in adolescent patients undergoing reduction mammoplasty.

Effect of transpulmonary pressure-directed mechanical ventilation on respiration in severe acute pancreatitis patient with intraabdominal hypertension

To assess the effect of mehanical ventilation (MV) guided by transpulmonary pressure (Ptp) on respiratory mechanics and gas exchange in severe acute pancreatitis patient with intraabdominal hypertension. Twelve severe acute pancreatitis patient with intraabdominal hypertension and acute respiratory distress syndrome(ARDS) underwent mechanical ventilation were involved from Jan to Dec 2013. PEEP levels were set to achieve a Ptp of 0 to 10 cm of water at end expiration. We also limited tidal volume to keep Ptp at less than 25 cm of water at end inspiration. Respiratory mechanics and gas-exchange were measured. Plat pressure (Pplat) increased and the compliance of chest wall (Ccw) decreased when intraabdominal pressure (IAP) increased. Pplat correlated with IAP positively (r2=0.741 9, P<0.05) and Ccw correlated with IAP negtively (r2=0.722 2, P<0.05), respectively.There were not corrletions between IAP and end-expiratory Ptp (Ptp-e) and end-inspiratory Ptp (Ptp-i) (P>0.05). Compared with baseline, after guiding MV with Ptp, the Level of PEEP (14.6±4.2) cmH2O vs (8.3±2.0) cmH2O, and Ptp-e (1.5±0.5) cmH2O vs (-2.3±1.4) cmH2O increased (P<0.05) and Ptp-i did not increase significantly (P>0.05). Ptp-e correlated with PEEP (r2=0.549, P<0.05) and end-expiratory esophageal pressure (Pes-e) (r2=0.260, P<0.05). Ptp-i correlated with Pplat (r2=0.523, P<0.05) and end-inspiratory esophageal pressure (Pes-i) (r2=0.231, P<0.05), but did not correlate with Tidal volume(VT) (r2=0.052 4, P>0.05). Compared with baseline, lung compliance (CL) (48.1±10.3) cmH2O vs (25.7±6.4) cmH2O and oxygenation index (PaO2/FiO2) (235±48) mmHg vs (160±35) mmHg improved obviously (P<0.05), dead space fraction (VD/VT) (0.48±0.07) vs (0.59±0.06) decreased (P<0.05), but Ccw and respiratory compliance(Cr) didn't improve (P>0.05). Transpulmonary pressure-directed mechanical ventilation in ARDS secondary to severe acute pancreatitis patient with intraabdominal hypertension could not only recruit the collapsed alveoli, improve lung compliance, increase oxygenation index and decrease dead space ventilation but also monitor lung stress to avoid alveoli overinflation, which might be lung protective.

Effect of endotracheal tube leakage on respiratory function monitoring: Comparison of three neonatal ventilators.

In preterm infants, lung function monitoring is important for lung-protective mechanical ventilation. In this study, we used a neonatal lung model to investigate the effect of endotracheal tube (ETT) leakage on the monitoring of tidal volume (VT) and lung mechanics using different ventilators. A neonatal lung model was ventilated via a 3 mm ETT using three ventilators, Babylog 8000, Leoni, and Stephanie. ETT leakage was simulated by open silicone tubes with different lengths. The volume delivered to the lung model was measured and compared with the displayed expiratory VT of the three ventilators. The effect of ETT leakage on lung mechanical parameters displayed by the ventilators was investigated for respiratory rates from 20 min-1 to 70 min-1 and a constant inspiratory time: expiratory time ratio of 1:1. The displayed ETT leakage depended on the size of the leak, ventilator settings, and the ventilator used. In the presence of ETT leakages, for all three ventilators, the displayed VT underestimated the true volume delivered to the lung. With increasing ETT leakage, displayed compliance was overestimated by Babylog 8000 and Stephanie, whereas Leoni underestimated compliance. The displayed resistance increased with increasing ETT leakage for the three ventilators, but quite different. The effect of ETT leakage on displayed VT and lung mechanical parameters is ventilator-dependent. ETT leakage can lead to incorrect measurements that indicate reduced VT, improvement of lung compliance, or ETT obstruction.

Preconditioning allows engraftment of mouse and human embryonic lung cells, enabling lung repair in mice.

Repair of injured lungs represents a longstanding therapeutic challenge. We show that human and mouse embryonic lung tissue from the canalicular stage of development (20-22 weeks of gestation for humans, and embryonic day 15-16 (E15-E16) for mouse) are enriched with progenitors residing in distinct niches. On the basis of the marked analogy to progenitor niches in bone marrow (BM), we attempted strategies similar to BM transplantation, employing sublethal radiation to vacate lung progenitor niches and to reduce stem cell competition. Intravenous infusion of a single cell suspension of canalicular lung tissue from GFP-marked mice or human fetal donors into naphthalene-injured and irradiated syngeneic or SCID mice, respectively, induced marked long-term lung chimerism. Donor type structures or 'patches' contained epithelial, mesenchymal and endothelial cells. Transplantation of differentially labeled E16 mouse lung cells indicated that these patches were probably of clonal origin from the donor. Recipients of the single cell suspension transplant exhibited marked improvement in lung compliance and tissue damping reflecting the energy dissipation in the lung tissues. Our study provides proof of concept for lung reconstitution by canalicular-stage human lung cells after preconditioning of the pulmonary niche.

Extract of &lt;i&gt;Brassica rapa&lt;/i&gt; suppresses ovalbumin-induced asthma by down-regulating NF-κB and p38 MAPK activity

Asthma is one of the most common chronic inflammatory diseases characterized by airway infiltration of inflammatory cells inducing hyper-responsiveness. Due to the inefficacy of currently used drugs to definitely cure asthma, there is an insistent need for identification of novel therapies. In the present research, efficiency of Brassica rapa extract in asthma-induced mouse model was investigated. Asthma was induced in mice by ovalbumin induction. The extract (125-500 mg/kg) effectively reduced ovalbumin-specific IgE in serum and levels of interleukins (IL): IL-4, IL-5 and IL-13 in bronchoalveolar lavage fluid (BALF). B. rapa extract inhibited inflammatory cell infiltration in BALF and also improved lung compliance and airway resistance. The extract caused marked reduction in the expression levels of phosphorylated ERK, p38, IκB-α and NF-κB, however dose-dependent activation of JNK was observed. The extract of B. rapa thus was effective in suppressing ovalbumin-induced asthma.

Therapeutic efficacy of human mesenchymal stromal cells in the repair of established ventilator-induced lung injury in the rat.

Rodent mesenchymal stem/stromal cells (MSCs) enhance repair after ventilator-induced lung injury (VILI). We wished to determine the therapeutic potential of human MSCs (hMSCs) in repairing the rodent lung. In series 1, anesthetized rats underwent VILI (series 1A, n = 8 to 9 per group) or protective ventilation (series 1B, n = 4 per group). After VILI, they were randomized to intravenous administration of (1) vehicle (phosphate-buffered saline); (2) fibroblasts (1 × 10 cells/kg); or (3) human MSCs (1 × 10 cells/kg) and the effect on restoration of lung function and structure assessed. In series 2, the efficacy of hMSC doses of 1, 2, 5, and 10 million/kg was examined (n = 8 per group). Series 3 compared the efficacy of both intratracheal and intraperitoneal hMSC administration to intravascular delivery (n = 5-10 per group). Series 4 examined the efficacy of delayed hMSC administration (n = 8 per group). Human MSC's enhanced lung repair, restoring oxygenation (131 ± 19 vs. 103 ± 11 vs. 95 ± 11 mmHg, P = 0.004) compared to vehicle or fibroblast therapy, respectively. hMSCs improved lung compliance, reducing alveolar edema, and restoring lung architecture. hMSCs attenuated lung inflammation, decreasing alveolar cellular infiltration, and decreasing cytokine-induced neutrophil chemoattractant-1 and interleukin-6 while increasing keratinocyte growth factor concentrations. The lowest effective hMSC dose was 2 × 10 hMSC/kg. Intraperitoneal hMSC delivery was less effective than intratracheal or intravenous hMSC. hMSCs enhanced lung repair when administered at later time points after VILI. hMSC therapy demonstrates therapeutic potential in enhancing recovery after VILI.

Intraoperative pulmonary function dynamics in adolescents undergoing reduction mammoplasty: A prospective case series.

Improvement of lung function following reduction mammoplasty has been previously reported among adult populations in the medical literature. To evaluate the intraoperative dynamics of pulmonary function in adolescents undergoing reduction mammoplasty. The present study is a prospective case series of female patients 13 to 18 years of age who underwent inferior pedicle reduction mammoplasty between November 20, 2006 and April 4, 2011. Documented variables included patient baseline characteristics, operation duration, muscle relaxant use and total breast tissue removed. Intraoperative pulmonary function data documented included: tidal volume, respiratory rate, peak inspiratory pressure, positive end-expiratory pressure, oxygen saturation percentage and pulmonary compliance. Differences in pulmonary function data were calculated as ratio between final and initial intraoperative values. Twenty-six patients were included in the analysis. Mean (± SD) age was 16.9±1.1 years and mean body mass index was 28.9±6.1 kg/m(2). Mean operation time was 218±52 min, with average total bilateral breast tissue removal of 1810±1065 g. Improvement in lung compliance was observed in 24 patients (92.3%; P<0.0001). Mean intraoperative lung compliance improvement was 23.92% (95% CI 8.3% to 37%; P=0.001). Intraoperative improvement in lung compliance was observed in adolescent patients undergoing reduction mammoplasty.

Alveolar recruitment maneuvers under general anesthesia: a systematic review of the literature.

The sigh is a normal homeostatic reflex that maintains lung compliance and decreases atelectasis. General anesthesia abolishes the sigh reflex with rapid onset of atelectasis in 100% of patients. Studies show a strong correlation between atelectasis and postoperative pulmonary complications, raising health-care costs. Alveolar recruitment maneuvers recruit collapsed alveoli, increase gas exchange, and improve arterial oxygenation. There is no consensus in the literature about the benefits of alveolar recruitment maneuvers. A systematic review is necessary to delineate their usefulness. The search strategy included utilizing PubMed, CINAHL, the Cochrane Library, the National Guideline Clearinghouse, and all subsequent research reference lists up to January 2014. Inclusion criteria involved studies that compared the use of an alveolar recruitment maneuver with a control group lacking an alveolar recruitment maneuver in adult surgical subjects not suffering from ARDS or undergoing cardiac or thoracic surgeries. Six randomized controlled trials of the 439 studies initially identified achieved a score of ≥ 3 on the Jadad scale and were included in this review. Alveolar recruitment maneuvers consisted of a stepwise increase in tidal volume to a plateau pressure of 30 cm H2O, a stepwise increase in PEEP to 20 cm H2O, or sustained manual inflations of the anesthesia reservoir bag to a peak inspiratory pressure of 40 cm H2O. Subjects in the alveolar recruitment maneuver groups experienced a higher intraoperative PaO2 with improved lung compliance. Different alveolar recruitment maneuvers were equally effective. There was a significant advantage when alveolar recruitment maneuvers were followed by PEEP application. Alveolar recruitment maneuvers followed by PEEP should be instituted after induction of general anesthesia, routinely during maintenance, and in the presence of a falling SpO2 whenever feasible. They allow the anesthesia provider to reduce the FIO2 while maintaining a higher SpO2 , limiting the masking of shunts. Utilization of alveolar recruitment maneuvers may reduce postoperative pulmonary complications and improve patient outcomes.

Alveolar recruitment maneuver during cesarean section and after delivery improves lung compliance

Aretha, D.1; Kiekkas, P.2; Protopappas, P.1; Dimitrakopoulou, K.1; Baxal, A.1; Mouratidou, A.1 Author Information

Intratracheal transfer of lung eosinophils reduces influenza virus burden in mice (INC8P.438)

Abstract Eosinophils, commonly known for anti-parasitic immunity and a controversial role in allergic asthma, may exhibit antiviral immunity against respiratory viruses. We have shown previously that mice subjected to a fungal asthma model were protected from morbidity associated with influenza A virus (IAV). Furthermore, we have also shown that mice studied in the model following resolution of allergic/eosinophilic inflammation and were more susceptible to influenza. We hypothesized that eosinophils promote viral clearance from the lungs. Lung eosinophils harvested from “allergic” mice were transferred directly into H1N1 influenza (A/CA/04/2009) infected mice. Recipients had improved lung compliance and reduced viral burden, although there was no change in weight compared to controls. The inflammatory response was equivalent between groups at day 3. There were fewer cells in airways of recipients by day 7, however, there were significantly more virus-specific CD8+ T cells present. The enhanced viral clearance was associated with increased IgA content in the airways of recipients. When mice which had achieved resolution of allergic inflammation prior to IAV infection were supplemented with eosinophils, viral burden also decreased, but the inflammatory profile was unaffected. Bone marrow-derived eosinophils killed IAV by a mechanism that appeared to be piecemeal degranulation. Taken together, these data suggest a novel function for eosinophils in altering the immune response to IAV.

Drainage of pleural effusion in mechanically ventilated patients: Time to measure chest wall compliance?

PurposePleural effusion (PE) is commonly encountered in mechanically ventilated, critically ill patients and is generally addressed with evacuation or by fluid displacement using increased airway pressure (PAW). However, except when massive or infected, clear evidence is lacking to guide its management. The aim of this study was to investigate the effect of recruitment maneuvers and drainage of unilateral PE on respiratory mechanics, gas exchange, and lung volume. Materials and methodsFifteen critically ill and mechanically ventilated patients with unilateral PE were enrolled. A 3-step protocol (baseline, recruitment, and effusion drainage) was applied to patients with more than 400 mL of PE, as estimated by chest ultrasound. Predefined subgroup analysis compared patients with normal vs reduced chest wall compliance (CCW). Esophageal and PAWs, respiratory system, lung and CCWs, arterial blood gases, and end-expiratory lung volumes were recorded. ResultsIn the whole case mix, neither recruitment nor drainage improved gas exchange, lung volume, or tidal mechanics. When CCW was normal, recruitment improved lung compliance (81.9 [64.8-104.1] vs 103.7 [91.5-111.7] mL/cm H2O, P < .05), whereas drainage had no significant effect on total respiratory system mechanics or gas exchange, although it measurably increased lung volume (1717 vs 2150 mL, P < .05). In the setting of reduced CCW, however, recruitment had no significant effect on total respiratory system mechanics or gas exchange, whereas pleural drainage improved respiratory system and CCWs as well as lung volume (42.7 [38.9-50.0] vs 47.0 [43.8-63.3], P < .05 and 97.4 [89.3-97.9] vs 126.7 [92.3-153.8] mL/cm H2O, P < .05 and 1580 vs 1750 mL, P < .05, respectively). ConclusionsDrainage of a moderate-sized effusion should not be routinely performed in unselected population of critically ill patients. We suggest that measurement of CCW may help in the decision-making process.

Novel therapeutic approach for pulmonary emphysema using gelatin microspheres releasing basic fibroblast growth factor in a canine model

The prognosis of patients with emphysema is poor as there is no truly effective treatment. Our previous study showed that the alveolar space was smaller and the microvessel density was higher in a canine emphysema model after the intrapulmonary arterial administration of gelatin microspheres slowly releasing basic fibroblast growth factor (bFGF-GMS). In the present study, we evaluated the functional effect of injecting bFGF-GMS via the pulmonary artery in this canine pulmonary emphysema model. Using the porcine pancreatic elastase (PPE)-induced total emphysema model, we approximated the value of lung compliance with a Power Lab System, and performed blood gas analysis in a control group, a total emphysema group, and a bFGF group in which bFGF-GMS were injected toward the whole pulmonary artery via the femoral vein. Each group comprised five dogs. Lung compliance was higher in the total emphysema group than in the control group (p=0.031), and the bFGF group showed no significant improvement of lung compliance vs. the total emphysema group (p=0.112). PaO2 (partial pressure of oxygen in arterial blood) was improved by administering bFGF-GMS in the total emphysema model (p=0.027). In the canine total emphysema model, blood gas parameters were improved by the whole pulmonary arterial administration of bFGF-GMS. This method has the potential to be an effective novel therapy for pulmonary emphysema.

Liquid ventilation.

Human have lungs to breathe air and they have no gills to breath liquids like fish. When the surface tension at the air-liquid interface of the lung increases as in acute lung injury, scientists started to think about filling the lung with fluid instead of air to reduce the surface tension and facilitate ventilation. Liquid ventilation (LV) is a technique of mechanical ventilation in which the lungs are insufflated with an oxygenated perfluorochemical liquid rather than an oxygen-containing gas mixture. The use of perfluorochemicals, rather than nitrogen as the inert carrier of oxygen and carbon dioxide offers a number of advantages for the treatment of acute lung injury. In addition, there are non-respiratory applications with expanding potential including pulmonary drug delivery and radiographic imaging. It is well-known that respiratory diseases are one of the most common causes of morbidity and mortality in intensive care unit. During the past few years several new modalities of treatment have been introduced. One of them and probably the most fascinating, is of LV. Partial LV, on which much of the existing research has concentrated, requires partial filling of lungs with perfluorocarbons (PFC's) and ventilation with gas tidal volumes using conventional mechanical ventilators. Various physico-chemical properties of PFC's make them the ideal media. It results in a dramatic improvement in lung compliance and oxygenation and decline in mean airway pressure and oxygen requirements. No long-term side-effect reported.