Pulmonary Gas Exchange Function Research Articles

Pulmonary AVM Embolization

Pulmonary arteriovenous malformations (PAVMs) are rare fistulous connections between pulmonary arteries and veins that, as in our case, are commonly associated with hereditary hemorrhagic telangiectasia (HHT). Embolotherapy, the mainstay of treatment for PAVMs, is a procedure in which the feeding arteries of a malformation are endovascularly occluded under fluoroscopic guidance. Effective and well-tolerated, embolotherapy has been shown to decrease right-to-left shunting following treatment and decrease risks of paradoxical embolization and lung hemorrhage and to improve pulmonary gas exchange and lung function. Patients are selected for treatment according to clinical suspicion for the presence of a PAVM and feeding artery diameter. The occlusion of PAVMs with arteries that exceed 2-3 mm in diameter is recommended. Diagnostic contrast-enhanced pulmonary angiography is performed via injection of contrast through a percutaneous catheter to characterize and confirm PAVMs suitable for embolization. Lesions are then treated by catheter-directed placement of embolic material— vascular plugs in our case—into the feeding artery, terminating blood flow to the area of the lesion. Although multiple PAVMs may be embolized during a single session, in patients with HHT, who may present with large numbers of PAVMs, treatment is limited by maximum contrast dosage, and additional sessions may be performed if PAVMs remain perfused.

Relationship between Pulmonary Gas Exchange Function and Brain Uptake Dynamics Investigated with Hyperpolarized 129Xe MR Imaging and Spectroscopy in a Murine Model of Chronic Obstructive Pulmonary Disease.

Chronic obstructive pulmonary disease (COPD) is a complex multisystem disease associated with comorbidities outside the lungs. The aim of this study was to measure changes in metrics of pulmonary gas exchange function and brain tissue metabolism in a mouse model of COPD using hyperpolarized 129Xe (HP 129Xe) MRI/MR spectroscopy (MRS) and investigate the relationship between the metrics of lung and brain. COPD phenotypes were induced in 15 mice by 6-week administration of cigarette smoke extract (CSE) and lipopolysaccharide (LPS). A separate negative control (NC) group was formed of 6 mice administered with saline for 6 weeks. After these 6-week administrations, the pulmonary gas exchange function parameter fD (%) and the rate constant, α (s-1), which are composed of the cerebral blood flow Fi and the longitudinal relaxation rate 1/T1i in brain tissue, were evaluated by HP 129Xe MRI/MRS. The fD of CSE-LPS mice was significantly lower than that of NC mice, which was in parallel with an increase in bronchial wall thickness. The α in the CSE-LPS mice decreased with the decrease of fD in contrast to the trend in the NC mice. To further elucidate the opposed trend, the contribution of T1i was separately determined by measuring Fi. The T1i in the CSE-LPS mice was found to correlate negatively with fD as opposed to the positive trend in the NC mice. The opposite trend in T1i between CSE-LPS and NC mice suggests hypoxia in the brain, which is induced by the impaired oxygen uptake as indicated by the reduced fD. This study demonstrates the feasibility of using HP 129Xe MRI/MRS to study pathological mechanisms of brain dysfunction in comorbidities with COPD.

Effect of tocilizumab on pulmonary gas exchange function in patients with severe COVID-19

Introduction. COVID-19 causes cytokine storm and acute respiratory distress syndrome, which can lead to severe lung damage and multiple organ dysfunction. Early use of monoclonal antibodies has shown promising results in cytokine storm therapy, but the effects on lung gas exchange function have not yet been studied.Aim. To evaluate the effect of tocilizumab on the dynamics of gas exchange parameters in patients with severe COVID-19. Material and methods. The study included 26 patients in whom gas exchange parameters (PaO2, PaCO2, P/f ratio), blood oxygen saturation (saturation), respiration rate, duration and parameters of high-flow oxygen therapy and noninvasive mechanical ventilation, length of stay in intensive care unit and total hospital length of stay were assessed.Results. Tocilizumab significantly improved oxygenation on the third day (p=0.001) from the time of drug administration.Conclusion. In the presented and analyzed cohort of patients with severe COVID-19 and cytokine storm, the normalization and significant increase of oxygenation parameters (PaO2, p=0.001; P/f ratio, p=0.001) were observed within three days after a single-dose tocilizumab administration in a complex intensive therapy. No significant dynamics in the respiratory support parameters was revealed, nor an effect of this therapy on the duration of the respiratory support or the reduction in the aggressiveness of its parameters was observed within three days after tocilizumab administration (p>0.05).

Dynamics of functional changes in the respiratory system after COVID-19-associated lung injury at one year after hospital discharge

Morphological examination reveals microcirculation disorders in combination with small areas of lung damage in the long term after COVID-19. Therefore, the function of the respiratory system should be assessed after COVID-19. Aim of this study was to evaluate the dynamics of respiratory dysfunction in patients with COVID-19-associated lung injury using a complex examination of lung function (spirometry, body plethysmography, and lung diffusion testing) one year after hospital discharge. Methods. 60 patients (38 men/22 women, aged 39 to 80 years) with a diagnosis of “COVID-19-associated interstitial process in the lungs” were examined. Lung function (spirometry, body plethysmography, and lung diffusion capacity testing) was examined in all patients twice, at 1 – 6 months (visit 1) and at 12 – 24 months (visit 2) after hospital discharge. Results. At visit 1, 60% of patients had restrictive pulmonary ventilation disorders. Obstructive ventilation disorders were detected in only 1 patient. Decreased lung diffusion capacity (D CO corr.) was found in 78% of patients. At visit 2, obstructive disorders were detected in 1 patient, and the frequency of restrictive ventilation disorders was 29%. Decreased DLCO corr. was noted in 57% of cases. The parameters of pulmonary ventilation and pulmonary gas exchange function differed significantly between visits. Significant correlations were found between changes in the functional parameters of the respiratory system and disorders identified at visit 1 after hospital discharge. Conclusion. Thus, there is a decrease in the lung diffusion capacity and the rate of restrictive ventilation disorders even one year after severe COVID-19-associated lung injury. However, our results suggest a marked improvement in respiratory system function over time.

Induction of severe hypoxemia and low lung recruitability for the evaluation of therapeutic ventilation strategies: a translational model of combined surfactant-depletion and ventilator-induced lung injury

BackgroundModels of hypoxemic lung injury caused by lavage-induced pulmonary surfactant depletion are prone to prompt recovery of blood oxygenation following recruitment maneuvers and have limited translational validity. We hypothesized that addition of injurious ventilation following surfactant-depletion creates a model of the acute respiratory distress syndrome (ARDS) with persistently low recruitability and higher levels of titrated “best” positive end-expiratory pressure (PEEP) during protective ventilation.MethodsTwo types of porcine lung injury were induced by lung lavage and 3 h of either protective or injurious ventilation, followed by 3 h of protective ventilation (N = 6 per group). Recruitment maneuvers (RM) and decremental PEEP trials comparing oxygenation versus dynamic compliance were performed after lavage and at 3 h intervals of ventilation. Pulmonary gas exchange function, respiratory mechanics, and ventilator-derived parameters were assessed after each RM to map the course of injury severity and recruitability.ResultsLung lavage impaired respiratory system compliance (Crs) and produced arterial oxygen tensions (PaO2) of 84±13 and 80±15 (FIO2 = 1.0) with prompt increase after RM to 270–395 mmHg in both groups. After subsequent 3 h of either protective or injurious ventilation, PaO2/FIO2 was 104±26 vs. 154±123 and increased to 369±132 vs. 167±87 mmHg in response to RM, respectively. After additional 3 h of protective ventilation, PaO2/FIO2 was 120±15 vs. 128±37 and increased to 470±68 vs. 185±129 mmHg in response to RM, respectively. Subsequently, decremental PEEP titration revealed that Crs peaked at 36 ± 10 vs. 25 ± 5 ml/cm H2O with PEEP of 12 vs. 16 cmH2O, and PaO2/FIO2 peaked at 563 ± 83 vs. 334 ± 148 mm Hg with PEEP of 16 vs. 22 cmH2O in the protective vs. injurious ventilation groups, respectively. The large disparity of recruitability between groups was not reflected in the Crs nor the magnitude of mechanical power present after injurious ventilation, once protective ventilation was resumed.ConclusionAddition of transitory injurious ventilation after lung lavage causes prolonged acute lung injury with diffuse alveolar damage and low recruitability yielding high titrated PEEP levels. Mimicking lung mechanical and functional characteristics of ARDS, this porcine model rectifies the constraints of single-hit lavage models and may enhance the translation of experimental research on mechanical ventilation strategies.

Regional Gas Exchange Measured by 129 Xe Magnetic Resonance Imaging Before and After Combination Bronchodilators Treatment in Chronic Obstructive Pulmonary Disease.

BackgroundHyperpolarized 129Xe magnetic resonance imaging (MRI) provides a non‐invasive assessment of regional pulmonary gas exchange function. This technique has demonstrated that chronic obstructive pulmonary disease (COPD) patients exhibit ventilation defects, reduced interstitial barrier tissue uptake, and poor transfer to capillary red blood cells (RBCs). However, the behavior of these measurements following therapeutic intervention is unknown.PurposeTo characterize changes in 129Xe gas transfer function following administration of an inhaled long‐acting beta‐agonist/long‐acting muscarinic receptor antagonist (LABA/LAMA) bronchodilator.Study TypeProspective.PopulationSeventeen COPD subjects (GOLD II/III classification per Global Initiative for Chronic Obstructive Lung Disease criteria) were imaged before and after 2 weeks of LABA/LAMA therapy.Field Strength/SequencesDedicated ventilation imaging used a multi‐slice 2D gradient echo sequence. Three‐dimensional images of ventilation, barrier uptake, and RBC transfer used an interleaved, radial, 1‐point Dixon sequence. Imaging was acquired at 3 T.Assessment129Xe measurements were quantified before and after LABA/LAMA treatment by ventilation defect + low percent (vendef + low) and by barrier uptake and RBC transfer relative to a healthy reference population (bar%ref and RBC%ref). Pulmonary function tests, including diffusing capacity of the lung for carbon monoxide (DLCO), were also performed before and after treatment.Statistical TestsPaired t‐test, Pearson correlation coefficient (r).ResultsBaseline vendef + low was 57.8 ± 8.4%, bar%ref was 73.2 ± 19.6%, and RBC%ref was 36.5 ± 13.6%. Following treatment, vendef + low decreased to 52.5 ± 10.6% (P < 0.05), and improved in 14/17 (82.4%) of subjects. However, RBC%ref decreased in 10/17 (58.8%) of subjects. Baseline measurements of bar%ref and DLCO were correlated with the degree of post‐treatment change in vendef + low (r = −0.49, P < 0.05 and r = −0.52, P < 0.05, respectively).ConclusionLABA/LAMA therapy tended to preferentially improve ventilation in subjects whose 129Xe barrier uptake and DLCO were relatively preserved. However, newly ventilated regions often revealed RBC transfer defects, an aspect of lung function opaque to spirometry. These microvasculature abnormalities must be accounted for when assessing the effects of LABA/LAMA therapy.Level of Evidence1Technical Efficacy Stage4

Effect of different oxygen concentrations developing pulmonary atelectasis of neonates during anesthesia: a randomized controlled trial

Objectives: This study sought to evaluate the effect of different oxygen concentrations on the development of pulmonary atelectasis in neonates during anesthesia with mechanical ventilation using ultrasound. Methods: Sixty-three neonates undergoing laparotomies were randomly divided into three groups. A: FiO2 = 30%, B: FiO2 = 40%, C: FiO2 = 50%. Ultrasound was performed to guide pulmonary resuscitation maneuvers after tracheal intubation and before tracheal extubation and performed at the end of surgery in each group to evaluate lung consolidation. The following parameters were assessed: (1) primary observation index: pulmonary consolidation score; (2) secondary observation index: area of pulmonary atelectasis, changes in oxygenation index, pulmonary atelectasis, and the incidence of hypoxemia; (3) pulmonary complications at 72 hours postoperatively. Results: There was a significant difference in pulmonary consolidation scores between the 30% and 50% groups (p &lt; 0.001) and the 40% and 50% groups (p &lt; 0.01); the difference between the 30% and 40% groups was not significant (p &gt; 0.05). The incidence of pulmonary atelectasis was 82.54%. Pulmonary atelectasis occurred in the posterior (81%) and in the right posteriolateral positions (51%). There was a significant change in the oxygenation index before and after pulmonary ultrasound-guided re-expansion before recruitment (T1) compared to after preoperative recruitment (T2) (p &lt; 0.001) and before postoperative recruitment (T3) compared to after postoperative recruitment (T4) (p &lt; 0.001). 6 children in the 30% oxygen concentration group developed mild hypoxemia and 2 children developed moderate hypoxemia; while no hypoxemia occurred in the remaining two groups. No pulmonary complications occurred at 72 hours postoperatively. Conclusions: 40% FiO2 may be the oxygen concentration that neither causes significant pulmonary atelectasis nor hypoxemia during the maintenance of mechanical ventilation during neonatal anesthesia. However, there may also be lower lung consolidation scores and no hypoxemia between 30% oxygen concentration and 40% we have not studied it. Pulmonary atelectasis is present in most anesthetized patients and occurs mainly in gravity-dependent areas, more on the right than on the left side. Pulmonary ultrasound-guided pulmonary recruitment maneuvers can significantly improve neonatal pulmonary gas exchange function.

Quantitative evaluation of pulmonary gas-exchange function using hyperpolarized 129 Xe CEST MRS and MRI.

Hyperpolarized 129 Xe gas MR has been a powerful tool for evaluating pulmonary structure and function due to the extremely high enhancement in spin polarization, the good solubility in the pulmonary parenchyma, and the excellent chemical sensitivity to its surrounding environment. Generally, the quantitative structural and functional information of the lung are evaluated using hyperpolarized 129 Xe by employing the techniques of chemical shift saturation recovery (CSSR) and xenon polarization transfer contrast (XTC). Hyperpolarized 129 Xe chemical exchange saturation transfer (Hyper-CEST) is another method for quantifying the exchange information of hyperpolarized 129 Xe by using the exchange of xenon signals according to its different chemical shifts, and it has been widely used in biosensor studies in vitro. However, the feasibility of using hyperpolarized 129 Xe CEST to quantify the pulmonary gas exchange function in vivo is still unclear. In this study, the technique of CEST was used to quantitatively evaluate the gas exchange in the lung globally and regionally via hyperpolarized 129 Xe MRS and MRI, respectively. A new parameter, the pulmonary apparent gas exchange time constant (Tapp ), was defined, and it increased from 0.63s to 0.95s in chronic obstructive pulmonary disease (COPD) rats (induced by cigarette smoke and lipopolysaccharide exposure) versus the controls with a significant difference (P=0.001). Additionally, the spatial distribution maps of Tapp in COPD rats' pulmonary parenchyma showed a regionally obvious increase compared with healthy rats. These results indicated that hyperpolarized 129 Xe CEST MR was an effective method for globally and regionally quantifying the pulmonary gas exchange function, which would be helpful in diagnosing lung diseases that are related to gas exchange, such as COPD.

Side Effects of Long-Term Continuous Intra-arterial Nimodipine Infusion in Patients with Severe Refractory Cerebral Vasospasm after Subarachnoid Hemorrhage.

Long-term continuous intra-arterial nimodipine infusion (CIAN) is a rescue therapy option in cases of severe refractory cerebral vasospasm (CV) following acute non-traumatic subarachnoid hemorrhage (SAH). However, CIAN therapy can be associated with relevant side effects. Available studies focus on intracerebral complications, whereas extracerebral side effects are rarely examined. Aim of the present study was to generate descriptive data on the clinical course during CIAN therapy and expectable extracerebral side effects. All patients treated with CIAN therapy for at least 5days between May 2011 and December 2015 were included. We retrospectively extracted data from the patient data management system regarding the period between 2days before the beginning and 5days after the termination of CIAN therapy to analyze the course of ventilation parameters and pulmonary gas exchange, hemodynamic support, renal and liver function, integrity of the gastrointestinal tract, and the occurrence of infectious complications. In addition, we recorded the mean daily values of intracranial pressure (ICP) and intracerebral problems associated with CIAN therapy. Data from 28 patients meeting inclusion criteria were analyzed. The mean duration of long-term CIAN therapy was 10.5±4.5days. Seventeen patients (60.7%) reached a good outcome level (Glasgow Outcome Scale [GOS] 4-5) 6months after SAH. An impairment of the pulmonary gas exchange occurred only at the very beginning of CIAN therapy. The required vasopressor support with norepinephrine was significantly higher on all days during and the first day after CIAN therapy compared to the situation before starting CIAN therapy. Two patients required short-time resuscitation due to cardiac arrest during CIAN therapy. Acute kidney injury was observed in four patients, and one of them required renal replacement therapy with sustained low-efficiency daily dialysis. During CIAN therapy, 23 patients (82.1%) needed the escalation of a previous antiinfective therapy or the onset of antibiotics which was in line with a significant increase of C-reactive protein and white blood cell count. Obstipation was observed in 22 patients (78.6%). Ten patients (35.7%) even showed insufficient defecation on at least seven consecutive days. Compared to the situation before, ICP was significantly higher during the whole period of CIAN therapy. Long-term CIAN therapy is associated with diverse side effects. The leading problems are an impairment of the hemodynamic situation and cardiac problems, an increase in infectious complications, a worsening of the motility of the gastrointestinal tract, and rising ICP values. Teams on neurointensive care units must be aware of these side effects to avoid that the beneficial effects of CIAN therapy on CV reported elsewhere are foiled by the problems this technique can be associated with.

Protective Effects of Cucurbitacin B on Acute Lung Injury Induced by Sepsis in Rats.

BackgroundThe aim of this study was to investigate the protective effects of cucurbitacin B (CuB) on sepsis-induced acute lung injury (ALI) in rats.Material/MethodsAn ALI model was made by cecal ligation and puncture (CLP) in SD rats. Rats were randomly divided into 5 groups (n=15 per group): animals undergoing a sham CLP (sham group); animals undergoing CLP (CLP control group); animals undergoing CLP and treated with CuB at 1 mg/kg of body weight (bw) (low-dose CuB [L-CuB] group), animals undergoing CuB at 2 mg/kg of bw (mid-dose CuB [M-CuB] group); and animals undergoing CuB at 5 mg/kg of bw (high-dose CuB [H-CuB] group). Samples of blood and lung tissue were harvested at different time points (6, 12, and 24 hour post-CLP surgery) for the detection of indicators which represented ALI. Five rats were respectively sacrificed at each time point. Pathological changes of lung tissue were observed by H&E staining. Another 50 rats were distributed into the same five groups to record the 72 hour survival rates.ResultsTreatment with CuB significantly increased the blood gas PaO2 levels and decreased lung wet/dry (W/D) ratio (p<0.05). It significantly reduced protein concentration, accumulation of the inflammatory cells, and levels of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6), (p<0.05), in the bronchoalveolar lavage fluid (BALF). Pulmonary pathological damage and survival rates at 72 hours were found to be effectively improved by CuB. In addition, CuB performed its pulmonary protection effects in a dose-depended manner.ConclusionsCuB can effectively improve the pulmonary gas exchange function, reduce pulmonary edema, and inhibit the inflammatory response in the lung, revealing that CuB may serve as a potential therapeutic strategy for sepsis-induced ALI.

Effect of two administration routes of Shenmai Injection () on pulmonary gas exchange function after tourniquet-induced ischemia-reperfusion.

To compare the effect between nebulized and intravenous administration of Shenmai Injection () on pulmonary gas exchange function of patients following tourniquet-induced lower limb ischemia-reperfusion. Thirty-eight patients scheduled for lower extremity surgery were randomized into three groups using the closed envelop method: Shenmai Injection was administered 30 min before tourniquet inflflation by nebulization [0.6 mL/kg in 10 mL normal saline (NS)] in the nebulization group or by intravenous drip (0.6 mL/kg dissolved in 250 mL of 10% glucose) in the intravenous drip group, and equal volume of NS was given intravenously in the NS group; 15 in each group. Arterial blood gases were analyzed, serum levels of malonaldehyde (MDA) and interleukine-6 (IL-6) and interleukine-8 (IL-8) were determined using the method of thiobarbituric acid reaction and enzyme-linked immuno sorbent assay respectively just before tourniquet inflflation (T0), and at 0.5 h (T1), 2 h (T2), 6 h (T3) after tourniquet deflflation. Compared with baselines at T0, MDA levels signifificantly increased at T2, T3 in the NS group and at T3 in the nebulization group, and IL-6 and IL-8 levels were signifificantly increased at T2, T3 in NS, the intravenous drip and the nebulization groups (P <0.05). Arterial pressure of oxygen (PaO2) at T3 was decreased, while alveolararterial oxygen tension showed difference (PA-aDO2) at T3 in the NS group; RI at T3 in both intravenous drip and the nebulization groups were enhanced (P <0.05). Compared with the NS group, MDA and IL-8 levels at T2, T3, IL-6 at T3 in the intravenous drip group, and IL-8 at T3 in the nebulization group were all remarkably increased (P <0.05). Additionally, MDA level at T3 in the nebulization group was higher than that in the intravenous drip group (P <0.05). Intravenous administration of Shenmai Injection provided a better protective effect than nebulization in mitigating pulmonary gas exchange dysfunction in patients following tourniquet-induced limb ischemia-reperfusion.

Clinical effectiveness of reamberin in treating outpatients with chronic obstructive pulmonary disease

Aim. To investigate the clinical effectiveness of meglumine sodium succinate in treating patients with chronic obstructive pulmonary disease in an outpatient setting. Methods. 93 patients with chronic obstructive pulmonary disease were examined. The influence of 3-month combined treatment with long-acting M-anticholinergic drug (tiotropium bromide), combination of salmeterol and fluticasone (Seretide) and antihypoxant drug - meglumine sodium succinate (Reamberin) in combination with breathing exercises on functional parameters of respiratory, cardiovascular system and quality of life was studied. Results. Signs of deceased pulmonary ventilation due to obstruction were revealed. Pulmonary hypertension and decreased right ventricle diastolic function were diagnosed in 89% of patients. Patients taking meglumine sodium succinate (Reamberin) showed statistically significant improvement of functional indices of respiratory and cardiovascular systems, as well as better quality of life after the treatment. In patients who were not taking meglumine sodium succinate, those changes were less prominent. Conclusion. Adding meglumine sodium succinate (Reamberin) to complex treatment of patients with chronic obstructive pulmonary disease supports the improvement in pulmonary function and macrocirculation, which demonstrates the improvement of pulmonary gas exchange function and improves quality of life.

The post-PE syndrome: a new concept for chronic complications of pulmonary embolism

Long-term follow-up studies have consistently demonstrated that after an episode of acute pulmonary embolism (PE), half of patients report functional limitations and/or decreased quality of life up to many years after the acute event. Incomplete thrombus resolution occurs in one-fourth to one-third of patients. Further, pulmonary artery pressure and right ventricular function remain abnormal despite adequate anticoagulant treatment in 10–30% of patients, and 0.5–4% is diagnosed with chronic thromboembolic pulmonary hypertension (CTEPH) which represents the most severe long term complication of acute PE. From these numbers, it seems that CTEPH itself is the extreme manifestation of a much more common phenomenon of permanent changes in pulmonary artery flow, pulmonary gas exchange and/or cardiac function caused by the acute PE and associated with dyspnea and decreased exercise capacity, which in analogy to post-thrombotic syndrome after deep vein thrombosis could be referred to as the post-pulmonary embolism syndrome. The acknowledgement of this syndrome would both be relevant for daily clinical practice and also provide a concept that aids in further understanding of the pathophysiology of CTEPH. In this clinically oriented review, we discuss the established associations and hypotheses between the process of thrombus resolution or persistence, lasting hemodynamic changes following acute PE as well as the consequences of a PE diagnosis on long-term physical performance and quality of life.

Impact of Detoxification Techniques on Pulmonary Gas Exchange Function in Patients with Generalized Peritonitis

Objective: to analyze the impact of different detoxification techniques on pulmonary gas exchange function in patients with generalized peritonitis complicated by multiple organ failure. Subjects and methods. One hundred and thirty patients with generalized peritonitis were examined. According to the used detoxification techniques, the patients were divided into 5 groups. All the patients underwent a comprehensive examination, the key element of which was the evaluation of gas exchange parameters. Results. Membrane plasmapheresis and plasmapheresis with sodium hypochlorite infusion to the plasma filter in patients with peritonitis are shown to improve pulmonary blood oxygenation.

87 Aerosolized Pfc Improves Pulmonary Function and Gas Exchange in a Preterm Lamb Model

Background: The aerosolization of PFC has emerged as a feasible alternative to the instillation for the experimental treatment of Respiratory Distress Syndrome.Aim: To determine the effects of aerosolized perfluorocarbon (PFC) on pulmonary gas exchange and lung function in preterm lambs.Methods: 12 preterm lambs (80-90%GE) were used. Lambs were randomly assigned to receive aerosolized PFC (10 ml/kg/h for 2h), delivered via an inhalation catheter, coupled to a jet nebuliser, and placed at the distal end of the endotracheal tube connected to a ventilator (PFC-aerosol) or not (CONTROL), both groups were maintained during 6h on IMV. Cardiovascular parameters, arterial partial pressure of CO2 (PaCO2), pH, oxygenation index (IO), arterial-alveolar oxygen ratio (a/APO2), alveolar-arterial oxygen gradient (A-a)DO2 and pulmonary function (compliance Cdyn and tidal volumen VT) were measured each 30 min during the experiment. Mean±SD, ANOVA, p< 0.05.Results: After 90min of treatment, animals in PFC-aerosol group, significantly improved gas exchange in comparison to Control group, being the improvement persistent until the end of the experiment: PaCO2 (37±6 vs. 93±12 mmHg), pH (7.41±0.11 vs. 7.15±0.09), IO (9±3 VS. 77±44), a/APO2 (0.29±0.11 vs. 0.04±0.02), (A-a)DO2 (294±133 vs. 572±20). Moreover, the pulmonary function significantly improved after 60 min of treatment in PFC-aerosol group compared to Control group, the improvement was sustained during the experimental period: Cdyn (0.53±0.05 vs. 0.27±0.04 ml/cmH2O/kg), VT (12.5±2.4 vs. 5.2±1.8 ml/kg). During all the experimental period there were not changes on cardiovascular parameters.Conclusion: Our results show that administration of aerosolized PFC improves pulmonary function and gas exchange. FIS07/0733-GV2007111046

Hemodynamic monitoring in one-lung ventilation

One-lung ventilation causes adverse effects in pulmonary gas exchange and cardiocirculatory function. These adverse effects become particularly important for patients with underlying cardiopulmonary comorbidities. Alterations in pulmonary gas exchange have been investigated in several experimental and clinical trials. However, the hemodynamic consequences of one-lung ventilation are to a great extent unknown. Furthermore, no conclusive recommendations exist as to which kind of hemodynamic monitoring should be preferred in the situation of one-lung ventilation. Many issues regarding hemodynamic monitoring in one-lung ventilation remain unacknowledged. This article will review the current literature on hemodynamic monitoring in one-lung ventilation in order to derive recommendations for the application of hemodynamic monitoring in this specific peri-operative situation.

Effects of Bolus Injection of Soybean-Based Fat Emulsion and Fatty Acids on Pulmonary Gas Exchange Function

To determine whether or not a "bolus injection" of soybean-based fat emulsion (SFE), which contains oleic acid (OA), a potent lung-toxic unsaturated C-18 fatty acid, can induce pulmonary dysfunction, we examined the effect of SFE injection on the partial oxygen pressure of arterial blood (Pao2) and pulmonary vascular permeability. In addition, we compared the effect of an injection of SFE with that of OA, soybean oil (a source of SFE), emulsified OA and C-18 fatty acids. Bolus injection of SFE (0.3-4.8 ml/kg) had little effect on Pao2) and pulmonary vascular permeability. Injection of an equivalent amount of OA, on the other hand, significantly decreased Pao2 and increased pulmonary vascular hyper-permeability. This decrease in Pao2 was attenuated by emulsification. Unemulsified soybean oil also induced a decrease in Pao2, although the effect was weaker than that of OA. Other unsaturated C-18 fatty acids (linoleic and linolenic acid) induced a decrease in Pao2 as potent as OA while stearic acid, a C-18 saturated fatty acid, had little effect. Although we did not observe pulmonary toxicity as a result of "bolus injection" of SFE, the chemical form, for example, emulsification and the degree of saturability of the carbon chain, seems to influence the pulmonary toxicities of lipids and fatty acids. Furthermore, the potent pulmonary toxicity of OA seems to depend not only on pulmonary vascular embolization but also pharmacological and/or inflammation-inducing properties.

Positive End-Expiratory Pressure and Nitric Oxide Inhalation in the Treatment of Acute Respiratory Distress Syndrome

Objective: to evaluate the impact of positive end-expiratory pressure (PEEP) on hemodynamic and gas-exchange effects of inhaled nitric oxide (iNO) in patients with acute respiratory distress syndrome (ARDS). Subjects and methods. The study included 27 cardiosurgical patients with ARDS who were divided into 2 groups, depending on the increment (A) in PaO2/FiO2 during iNO delivery (5 ppm): A PaO2/FiO2 &gt; 15% [Group A (n=13)] and APaO2/FiO2 &lt; 15% [Group B (n=14)]. The impact of different end-expiratory pressures (0, 4, 8, 12, and 16 cm H2O) on the parameters of pulmonary gas-exchange function, hemodynamics, O2 transport-uptake, respiratory biomechanics in the presence and absence of iNO delivery was examined. Results. In Groups A and B patients receiving no iNO, there were increases in PaO2/FiO2 and thoracopulmonary compliance (p&lt;0.05), with end-expiratory pressure being elevated from 0 to 8 cm H2O. The rise of PEEP from 8 to 12 and 16 cm H2O in the absence of iNO delivery was not further accompanied by increased PaO2/FiO2 and thoracopulmonary compliance. Only in Group A, the effect of iNO on pulmonary oxygenating function was potentiated with end-expiratory pressure being increased from 0 to 8 cm: the increment of PaO2/FiO2 during iNO delivery accordingly increased from 21±3 to 38±6 mm Hg. In this group, a subsequent increase of PEEP to 12—16 cm H2O did not lead to the enhanced effect of iNO on arterial oxygenation. Conclusion. PEEP creation attended by increased thoracopulmonary compliance potentiates the effect of iNO on the pulmonary oxygenating function only in patients in whom the use of iNO is effective when end-expiratory pressure is zero.

Respiratory and haemodynamic effects of volume-controlled vs pressure-controlled ventilation during laparoscopy: a cross-over study with echocardiographic assessment

The effects of pressure-controlled (PC) ventilation on the ventilatory and haemodynamic parameters during laparoscopy procedures had not been carefully assessed. This prospective cross-over study was undertaken to compare how volume-controlled (VC) and PC modes could affect pulmonary mechanics, gas exchange, and cardiac function in patients undergoing laparoscopy. Twenty-one patients undergoing laparoscopic urological procedures had their lungs ventilated at the beginning with VC ventilation. PC ventilation was instituted at the end of the VC sequence. Ventilator settings were adjusted to keep tidal volume, respiratory rate, and Fi(o(2)) constant in every mode. A complete set of ventilatory, haemodynamic, and gas exchange parameters was obtained under VC after 40 min of pneumoperitoneum and 20 min after switching for PC. Transoesophageal echocardiography was performed in order to evaluate systolic and diastolic function of the heart. When VC was switched to PC, peak airway pressure decreased [mean (sd) 32 (6) vs 27 (6) cm H(2)O; P < 0.0001], peak inspiratory flow increased [17 (3) vs 48 (8) litre min(-1); P < 0.0001), and dynamic compliance improved [+15 (8)%]. No difference was noted for static airway pressure, static compliance, and arterial oxygenation. No significant change could be demonstrated in the systolic [left ventricular end-systolic wall stress 66 (16) vs 63 (14) x 10(3) dyn cm(-2) m(-2)] or diastolic function [early diastolic velocity 10.3 (2.5) vs 10.5 (2.7) cm s(-1)]. In this study, no short-term beneficial effect of PC ventilation could be demonstrated over conventional VC ventilation in patients with pneumoperitoneum.

Effects of a recombinant surfactant protein-C-based surfactant on lung function and the pulmonary surfactant system in a model of meconium aspiration syndrome*

Meconium aspiration syndrome (MAS) remains a relevant cause of neonatal respiratory failure and is characterized by severe impairment of pulmonary gas exchange, surfactant inactivation, and pronounced inflammatory changes. Surfactant administration has been shown as an effective treatment strategy in MAS. The present study aimed at investigating the impact of a recombinant surfactant protein (SP)-C-based surfactant on pulmonary gas exchange and lung function in this model of neonatal lung injury. Furthermore, SP-B and -C were determined on the transcriptional and protein level. Laboratory experiment. University laboratory. Twenty three newborn piglets (median age 6 days, weight 1900-2500 g). Piglets were intubated and mechanically ventilated and then received 20% sterile meconium (5 mL/kg) for induction of lung injury. After 30 mins, animals were randomized for control (n = 7, MAS controls), recombinant SP-C surfactant (n = 8), or natural surfactant (n = 8). Surfactant preparations were administered as an intratracheal bolus (75 mg/kg), and animals were ventilated for another 330 mins. Nonventilated newborn piglets at term (n = 28; median weight 1484 g, range 720-1990 g) served as a healthy reference group (healthy controls). Lung function variables, arterial blood gas samples, and lung tissues were obtained. Expression of SP-B and -C messenger RNA was quantified in left lung lobe tissue using real-time polymerase chain reaction. Protein concentrations were determined by enzyme-linked immunosorbent assay. Scanning electron microscopy and transmission electron microscopy were performed in tissue samples of the right lung lobe. Compared with healthy controls, SP-B messenger RNA expression was significantly increased in MAS (p < .02), whereas SP-C messenger RNA expression was found to be significantly reduced (p < .001). SP concentrations, however, were not significantly different. Although a significant improvement of gas exchange and lung function was observed after surfactant administration in both groups, surfactant messenger RNA expression and protein concentrations were not significantly altered. Scanning and transmission electron microscopy showed severe pulmonary ultrastructural changes after meconium aspiration improving after surfactant treatment. Impairment of lung function in MAS, associated with marked changes in SP messenger RNA expression, can be sufficiently treated using recombinant SP-C-based or natural surfactant. Despite improved lung function and gas exchange as well as pulmonary ultrastructure after treatment, pulmonary SP messenger RNA expression and concentrations remained significantly affected, giving important insight into the time course following surfactant treatment in MAS.