Joan R. Masclans

Effect of high-flow nasal cannula and body position on end-expiratory lung volume: a cohort study using electrical impedance tomography.

BACKGROUND: Electrical impedance tomography measures changes in lung impedance, which are mainly related to changes in lung volume. We used electrical impedance tomography to investigate the effects of high-flow nasal cannula (HFNC) and body position on global and regional end-expiratory lung impedance variation (ΔEELI). METHODS: Prospective study with 20 healthy adults. Two periods were defined: the first in supine position and the second in prone position. Each period was divided into 3 phases. In the first and the third phases the subjects were breathing ambient air, and in the second HFNC was implemented. Four regions of interest were defined: 2 ventral and 2 dorsal. For each respiratory cycle, global and regional ΔEELI were measured by electrical impedance tomography and were expressed as a function of the tidal variation of the first stable respiratory cycle (units). RESULTS: HFNC increased global EELI by 1.26 units (95% CI 1.20–1.31, P < .001) in supine position, and by 0.87 units (95% CI 0.82–0.91, P < .001) in prone position. The distribution of ΔEELI was homogeneous in prone position, with no difference between ventral and dorsal lung regions (−0.01 units, 95% CI −0.01 to 0, P = .18), while in supine position a significant difference was found (0.22 units, 95% CI 0.21–0.23, P < .001) with increased EELI in ventral areas. CONCLUSIONS: HFNC increased global EELI in our population, regardless of body position, suggesting an increase in functional residual capacity. Prone positioning was related to a more homogeneous distribution of ΔEELI, while in supine position ΔEELI was higher in the ventral lung regions.

Effect of Inverse I E Ratio Ventilation on Pulmonary Gas Exchange in Acute Respiratory Distress Syndrome

Background: It is not known whether inverse I:E ratio ventilation (IRV) offers any real benefit over conventional mechanical ventilation with positive end-expiratory pressure (CMV-PEEP) at similar levels of end-expiratory pressure. Methods: The effects of volume-controlled and pressure-controlled IRV (VC-IRV and PC-IRV, respectively) on V A /Q inequality were compared with those of CMV-PEEP at a similar level of end-expiratory pressure and with CMV without PEEP (CMV) in eight patients in the early stages of acute respiratory distress syndrome (ARDS). Respiratory blood gases, inert gases, lung mechanics, and hemodynamics were measured 30 min after the onset of each ventilatory mode. Results: Recruitment of nonventilated, poorly ventilated (or both) but well-perfused alveoli increased the partial pressure of oxygen (Pa O2 ) during CMV-PEEP (+13 mmHg) and IRV-VC (+10 mmHg; P < 0.05) compared with CMV. In contrast, PC-IRV did not affect Pa O2 but caused a decrease in Pa CO2 (-7 mmHg; P < 0.05). The latter was due to a concomitant decrease in dead space (P < 0.01) and shift to the right of V A /Q distributions. During PC-IRV, the increase in the mean of blood flow distribution (mean Q; P < 0.01) without a change in the dispersion (log SD Q) did not result in an increase in Pa O2 probably because it reflected redistribution of blood flow within wellventilated areas. Conclusions: Short-term PC-IRV improved carbon dioxide clearance, but the lung became less efficient as an oxygen exchanger. Furthermore, based on mean airway and plateau pressures, the risk of barotrauma was not reduced with this type of ventilation.

Quality of Life, Pulmonary Function, and Tomographic Scan Abnormalities After ARDS

BACKGROUND ARDS can produce a loss of lung function with persistent sequelae. This study aimed to evaluate health-related quality of life (HRQL) in survivors of ARDS compared with a healthy reference population and to determine the middle/long-term radiographic abnormalities and functional status, as well as their relation to observed HRQL, in these patients. METHODS This was a prospective study carried out in three ICUs. HRQL in patients was determined with the Nottingham Health Profile immediately after ARDS diagnosis and 6 months after diagnosis. Patients underwent complete respiratory function testing, chest CT scan study, and the 6-min walk test. RESULTS Follow-up was conducted in 38 patients with ARDS. Survivors of ARDS presented a poorer overall HRQL vs the general population, mainly because of lower scores in the dimensions related to mobility, energy, and social isolation. Limitations in daily life activities were documented in 40%. Respiratory function was altered in 67%, with a restrictive respiratory pattern in 58%. Radiologic study disclosed alterations in 76% (mainly reticular pattern). Patients were able to cover only 366 m (318-411 m) in the 6-min walk test and had a minimum pulse oximetry of 93% (90%-94%). A significant correlation was documented between the overall quality of life at first and at 6 months (r = 0.68, P < .01). CONCLUSIONS Survivors of ARDS after 6 months had a poorer HRQL than the healthy population and showed mild radiographic and functional involvement. Early HRQL study in these patients enabled early detection of those who would present more long-term HRQL morbidity.

Human Mesenchymal Stem Cells Overexpressing the IL-33 Antagonist Soluble IL-1 Receptor–Like–1 Attenuate Endotoxin-Induced Acute Lung Injury

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are characterized by pulmonary edema attributable to alveolar epithelial-interstitial-endothelial injury, associated with profound inflammation and respiratory dysfunction. The IL-33/IL-1 receptor-like-1 (ST2) axis plays a key role in the development of immune-inflammatory responses in the lung. Cell-based therapy has been recently proposed as an effective alternative for the treatment of ALI and ARDS. Here, we engineered human adipose tissue-derived mesenchymal stem cells (hASCs) overexpressing soluble IL-1 receptor-like-1 (sST2), a decoy receptor for IL-33, in order to enhance their immunoregulatory and anti-inflammatory properties when applied in a murine ALI model. We administered both hASCs and hASC-sST2 systemically at 6 hours after intranasal LPS instillation, when pathological changes had already occurred. Bioluminescence imaging, immunohistochemistry, and focused transcriptional profiling confirmed the increased presence of hASCs in the injured lungs and the activation of an immunoregulatory program (CXCR-4, tumor necrosis factor-stimulated gene 6 protein, and indoleamine 2,3-dioxygenase up-regulation) in these cells, 48 hours after endotoxin challenge. A comparative evaluation of hASCs and the actions of hASC-sST2 revealed that local sST2 overproduction by hASC-sST2 further prevented IL-33, Toll-like receptor-4, IL-1β, and IFN-γ induction, but increased IL-10 expression in the injured lungs. This synergy caused a substantial decrease in lung airspace inflammation and vascular leakage, characterized by significant reductions in protein content, differential neutrophil counts, and proinflammatory cytokine (TNF-α, IL-6, and macrophage inflammatory protein 2) concentrations in bronchoalveolar lavage fluid. In addition, hASC-sST2-treated ALI lungs showed preserved alveolar architecture, an absence of apoptosis, and minimal inflammatory cell infiltration. These results suggest that hASCs genetically engineered to produce sST2 could become a promising therapeutic strategy for ALI/ARDS management.

Early non-invasive ventilation treatment for severe influenza pneumonia

Abstract The role of non-invasive ventilation (NIV) in acute respiratory failure caused by viral pneumonia remains controversial. Our objective was to evaluate the use of NIV in a cohort of (H1N1)v pneumonia. Usefulness and success of NIV were assessed in a prospective, observational registry of patients with influenza A (H1N1) virus pneumonia in 148 Spanish intensive care units (ICUs) in 2009–10. Significant variables for NIV success were included in a multivariate analysis. In all, 685 patients with confirmed influenza A (H1N1)v viral pneumonia were admitted to participating ICUs; 489 were ventilated, 177 with NIV. The NIV was successful in 72 patients (40.7%), the rest required intubation. Low Acute Physiology and Chronic Health Evaluation (APACHE) II, low Sequential Organ Failure Assessment (SOFA) and absence of renal failure were associated with NIV success. Success of NIV was independently associated with fewer than two chest X-ray quadrant opacities (OR 3.5) and no vasopressor requirement (OR 8.1). However, among patients with two or more quadrant opacities, a SOFA score ≤7 presented a higher success rate than those with SOFA score >7 (OR 10.7). Patients in whom NIV was successful required shorter ventilation time, shorter ICU stay and hospital stay than NIV failure. In patients in whom NIV failed, the delay in intubation did not increase mortality (26.5% versus 24.2%). Clinicians used NIV in 25.8% of influenza A (H1N1)v viral pneumonia admitted to ICU, and treatment was effective in 40.6% of them. NIV success was associated with shorter hospital stay and mortality similar to non-ventilated patients. NIV failure was associated with a mortality similar to those who were intubated from the start.

Gas exchange and pulmonary haemodynamic responses to fat emulsions in acute respiratory distress syndrome

ObjectiveTo investigate the gas exchange and pulmonary haemodynamic responses to two different intravenous fat emulsions in patients with acute respiratory distress syndrome (ARDS).DesignProspective, randomized, double-blind, placebo-controlled study.SettingIntensive care unit in a university-affiliated hospital.Patients21 patients with ARDS [mean age, 57 ± 3 (SEM) years; Acute Physiology and Chronic Health Evaluation II, 20 ± 3; Murray’s score, 2.85 ± 0.12] consecutively admitted.InterventionsPatients were assigned to three groups (n=7 each): group A (LCT) received long-chain triglycerides (20 % LCT), group B (MCT/LCT), medium-chain triglycerides/long-chain triglycerides (20% MCT/LCT: 50/50) and group C placebo (0.9% sodium chloride, NaCl). The infusion was always given at the rate of 2 mg/kg min over a total period of 12 h, with a volume infusion of 500 ml in each group.MeasurementsData were collected before, immediately after and 12 h after infusion ceased. Pulmonary and systemic haemodynamic and gas exchange variables were measured at each time point. Serum triglyceride cholesterol, and non-esterified fatty acids levels were measured.ResultsDuring LCT infusion, cardiac output, oxygen consumption and oxygen delivery increased (all p<0.05), whereas pulmonary haemodynamics, arterial oxygen tension, mixed venous partial pressure of oxygen and venous admixture ratio remained essentially unaltered. No changes were observed following MCT/LCT infusion.ConclusionsThe administration of LCT emulsion given at a slow rate did not alter arterial oxygenation because of the beneficial effect of a high cardiac output, hence offsetting the detrimental effect of increased O2 consumption.

Effects of salbutamol on exhaled breath condensate biomarkers in acute lung injury: prospective analysis

IntroductionThe benefits of β-adrenergic stimulation have been described in acute lung injury (ALI), but there is still no evidence of its anti-inflammatory effect in these patients. Biomarkers in exhaled breath condensate (EBC) were used to study the effects of salbutamol on lung inflammation in mechanically ventilated patients with ALI.MethodsEBC was collected before and 30 minutes after administration of inhaled salbutamol (800 μg). The following parameters were measured in the samples: volume obtained, conductivity, pH after helium deaeration, and concentration of nitrites, nitrates and 8-isoprostane. The leukotriene B4 concentration was measured after sample lyophilization and reconstitution. Results are expressed as the median (interquartile range).ResultsEBC was obtained from six ALI patients, with a median age of 56 (46 to 76) years. At the time of EBC collection, the Lung Injury Score was 3 (2.3 to 3.1) and the PaO2/FIO2 ratio was 133 (96 to 211) mmHg. A significant increase in deaerated EBC pH was observed after salbutamol administration (7.66 (7.58 to 7.75) versus 7.83 (7.67 to 7.91), P = 0.028). Trends toward decreased nitrosative species (18.81 (13.33 to 49.44) μM versus 21.21 (8.07 to 29.83) μM, P = 0.173) and decreased 8-isoprostane concentration (11.64 (7.17 to 17.13) pg/ml versus 6.55 (4.03 to 9.99) pg/ml, P = 0.068) were detected. No changes in leukotriene B4 concentration were found (1.58 (0.47 to 3.57) pg/ml versus 2.06 (1.01 to 3.01) pg/ml, P = 0.753).ConclusionEBC analysis is a noninvasive technique that can be used to monitor ventilated patients. In EBC from a small cohort of patients with ALI, inhaled salbutamol significantly decreased airspace acidosis, a marker of inflammation, and was associated with a trend toward decreased markers of nitrosative and oxidative stress.

Eicosanoids and fat emulsions in acute respiratory distress syndrome patients

Lipid emulsions have been associated with changes in pulmonary function. Although these changes were related to the physical effects of the infusion-induced lipemia on gas exchange, several animal and human studies suggest that the impairment in pulmonary function observed with lipid infusions was mediated by prostaglandins. Prostaglandins are synthesized enzymatically from essential fatty acids. We studied the effects of two lipid emulsions, with different amounts of essential fatty acids (20% long-chain triacylglycerols [LCT] with 55% of linoleic acid and 7% of alpha linolenic acid in 100 g of emulsion, and a physical mixture of 20% medium-chain triacyglycerols [MCT] and LCT with 26% of linoleic acid and 4% of alpha linolenic acid in 100 g of emulsion), on plasma levels of eicosanoids in patients with acute respiratory distress syndrome (ARDS). Although in patients with ARDS, plasma levels of prostanoids were higher than the reference values, neither lipid emulsion, administered at the rate of 2 mg.kg-1.min-1 induced significant changes in the eicosanoids except for a decrease in systemic-pulmonary arterial 6-keto prostaglandin F1 alpha difference.

Severe acute pancreatitis: treatment with somatostatin.

Objective: To investigate the efficacy of somatostatin for the treatment of severe acute pancreatitis. Design: Prospective, randomized and unblinded study. Setting: A general intensive care unit (ICU) in a university hospital. Patients: 50 patients with severe acute pancreatitis. Interventions: All patients received the conventional treatment for this clinical condition. The study group received, in addition, somatostatin over a 10-day period. Measurements and results: We evaluated age, gender, etiology of the pancreatitis, severity of the illness, complications, length of hospitalization, and mortality in the ICU. The patients were classified as severe (Acute Physiology and Chronic Health Evaluation II score, Ransons criteria, and computed tomography Balthazar classification). Biliary lithiasis was the most common etiologic factor (63.6 % in the control group, 37.5 % in study group; NS). The study group required fewer overall surgical interventions than the control group (45.8 vs 86.4 %; p = 0.005). Late surgical procedures related to the evolution of pancreatic necrosis were more common in the controls (63.6 vs 37.5 %; p = 0.07). No differences in length of stay in hospital or mortality in the ICU were observed. Conclusion: The only advantage of somatostatin administration in the patients studied was a slight reduction in the need for surgery due to local complications.

Appropriateness is Critical

Inappropriate empirical antibiotic therapy for severe infections in the intensive care unit is a modifiable prognostic factor that has a great effect on patient outcome and health care resources. Inappropriate treatment is usually associated with microorganisms resistant to the common antibiotics, which must be empirically targeted when risk factors are present. Previous antibiotic exposure, prolonged length of hospital stay, admission category, local susceptibilities, colonization pressure, and the presence of invasive devices increase the likelihood of infection by resistant pathogens. Consideration of issues beyond in vitro susceptibility, such as antibiotic physicochemistry, tissue penetration, and pharmacokinetic/pharmacodynamic-driven dosing, is mandatory for the optimization of antibiotic use.