Methods for determination of optimal positive end-expiratory pressure: a protocol for a scoping review.

INTRODUCTION: Titrated application of positive end-expiratory pressure (PEEP) is an important part of any mechanical ventilation strategy. However, the method by which the optimal PEEP is determined and titrated varies widely. Methods for determining optimal PEEP have been assessed using a variety of different study designs and patient populations. We will conduct a scoping review to systematically identify all methods for determining optimal PEEP, and to identify the patient populations, outcomes measured and study designs used for each method. The goal will be to identify gaps in the optimal PEEP literature and identify areas where there may be an opportunity to further systematically synthesise and meta-analyse existing literature. METHODS AND ANALYSIS: Using scoping review methodology, we will generate a comprehensive search strategy based on inclusion and exclusion criteria generated using the population, concept, context framework. Five different databases will be searched (MEDLINE, EMBASE, CENTRAL, Web of Science and Scopus). Three investigators will independently screen titles and abstracts, and two investigators will independently complete full-text review and data extraction. Included citations will be categorised in terms of PEEP method, study design, patient population and outcomes measured. The methods for PEEP titration will be described in detail, including strengths and limitations. ETHICS AND DISSEMINATION: Given this is a synthesis of existing literature, ethics approval is not required. The results will be disseminated to stakeholders via presentation at local, regional and national levels, as well as publication in a high-impact critical care journal. There is also the potential to impact local clinical care protocols and inform broader clinical practice guidelines undertaken by societies.

Left Main Coronary Artery Compression in Pulmonary Arterial Hypertension: Percutaneous Treatment to Improve Symptoms.

A 51-year-old woman with pulmonary arterial hypertension presented with progressive chest pain and dyspnea. Computed tomography imaging showed significant enlargement of her main pulmonary artery (PA) and was suggestive of left main coronary artery (LMCA) compression by the PA. The patient underwent percutaneous coronary intervention, which confirmed the diagnosis and a stent was deployed to the LMCA. Three months after the procedure the patient has near resolution of her symptoms. LMCA compression by an enlarged PA is an important cause of chest pain in patients with pulmonary arterial hypertension and can be managed safely and effectively with percutaneous coronary intervention and stenting.

Une femme de 51 ans atteinte d'hypertension artérielle pulmonaire présentait des symptômes progressifs de dyspnée et de douleur thoracique. Les images de la tomographie par ordinateur ont révélé un élargissement de l'artère pulmonaire (AP) principale et indiquaient une compression de l'artère coronaire gauche principale (ACGP) par l'AP. L'intervention coronarienne percutanée subie par la patiente a confirmé le diagnostic, et une endoprothèse coronaire a été déployée à l'intérieur de l'ACGP. Les symptômes de la patiente avaient pratiquement disparu trois mois après l'intervention. La compression de l'ACGP par une AP élargie est une cause importante de douleur thoracique chez les patients atteints d'hypertension artérielle pulmonaire qui peut être traitée de façon sûre et efficace par une intervention coronarienne percutanée et une endoprothèse coronaire.

The effect of acute outdoor air pollution on peak expiratory flow in individuals with asthma: A systematic review and meta-analysis.

OBJECTIVES: Acute exposures to outdoor air pollution have been shown to reduce lung function in children with asthma, but the effect on adults with asthma has not been established in a meta-analysis. The objective of this study was to conduct a systematic literature review and meta-analysis of studies that assessed the relationship of outdoor air pollution and peak expiratory flow (PEF) in adults with asthma. METHODS: Studies that contained data on outdoor air pollution levels (PM10, PM2.5, or NO2) and PEF in adults with asthma were eligible for inclusion. Effect estimates were quantified for each air pollution measure using random effects models. Heterogeneity was investigated with the Q-test and I2 statistics. Meta-regression and subgroup analyses were conducted to determine differences in effect by air pollution measures and the inclusion of smokers. RESULTS: A total of 22 effect estimates from 15 studies were included in this review. A 10 µg/m3 increase in acute PM10 exposure was associated with a -0.19 L/min (95% CI: 0.30, -0.09) change in PEF. For both PM10 and PM2.5, the inclusion of current smokers was a significant source of heterogeneity among studies (meta-regression: p = 0.04 and p = 0.03). Among studies that only included non-smokers, a 10 µg/m3 increase in acute exposure to PM10 and PM2.5 was associated with changes in PEF of -0.25 L/min (95% CI: 0.38, -0.13) and -1.02 L/min (95% CI: 1.79, -0.24), respectively. CONCLUSIONS: This study provides evidence that acute increases in PM10 and PM2.5 levels are associated with decreases in PEF in adults with asthma, particularly among non-smokers.

Effect of outdoor particulate air pollution on FEV1 in healthy adults: a systematic review and meta-analysis.

The effect of acute and long-term exposures to outdoor particulate air pollution on lung function in healthy adults is not well established. The objective of this study was to conduct a systematic literature review and meta-analysis of studies that assessed the relationship of outdoor particulate air pollution and lung function in healthy adults. Studies that contained data on outdoor air particulate matter levels (PM10 or PM2.5) and forced expiratory volume in 1 s (FEV1) in healthy adults were eligible for inclusion. Effect estimates, in relation to long-term and acute exposures, were quantified separately using random effects models. A total of 27 effect estimates from 23 studies were included in this review. Acute exposures were typically assessed with PM2.5, while long-term exposures were predominantly represented by PM10 A 10 µg/m3 increase in short-term PM2.5 exposure (days) was associated with a -7.02 mL (95% CI -11.75 to -2.29) change in FEV1 A 10 µg/m3 difference in long-term PM10 exposure was associated with a -8.72 mL (95% CI -15.39 to -2.07) annual change in FEV1 and an absolute difference in FEV1 of -71.36 mL (95% CI -134.47 to -8.24). This study provides evidence that acute and long-term exposure to outdoor particulate air pollution are associated with decreased FEV1 in healthy adults. Residual confounding from other risk factors, such as smoking, may explain some of the effect for long-term exposures. More studies are required to determine the relationship of long-term exposure to PM2.5 and short-term exposure to PM10, which may have different biologic mechanisms.

Hyperacute Superior Vena Cava Syndrome associated with Central Venous Catheter Insertion.

Superior vena cava (SVC) syndrome is classically thought of as a complication of malignancy. However, SVC syndrome secondary to indwelling central venous catheters (CVCs) is another important entity. Amongst those with CVCs who develop SVC syndrome, the majority are attributed to thrombosis. Aside from thrombosis, CVCs can lead to SVC syndrome secondary to mechanical obstruction of blood flow in an already narrowed vessel.We present the first case of hyperacute SVC syndrome that developed within 6 hours of insertion of a CVC into a patient's right internal jugular vein alongside a pre-existing right internal jugular tunnelled dialysis line. With removal of the line, the patient's symptoms resolved completely within hours. The patient also was found to have stenosis of superior vena cava, likely secondary to multiple instrumentations.Physicians must be diligent to monitor for this complication in patients who have had previous instrumentations of major vessels when inserting CVCs. HOW TO CITE THIS ARTICLE: Edginton S, Fundytus A. Hyperacute Superior Vena Cava Syndrome associated with Central Venous Catheter Insertion. Indian J Crit Care Med 2019;23(3):152-154.

Effects of Rituximab and Infliximab Treatment on Carboxypeptidase B and Its Substrates in RA Synovium.

OBJECTIVE: We evaluated the synovial effects of 2 potent biologic rheumatoid arthritis (RA) therapies, focusing on their effect on the expression level of carboxypeptidase B (CPB) and its substrates. METHODS: Patients with RA receiving infliximab (IFX; n = 9) or rituximab (RTX; n = 5) had an arthroscopic synovial biopsy at baseline and 16 weeks posttherapy. Expression of CPB, C5a, osteopontin (OPN), CD3, CD20, CD55, and CD68 was assessed by immunohistochemistry and image analysis, and compared with OA synovium. RA disease activity score was assessed at multiple timepoints. Serial serum samples were analyzed for soluble CPB and C5a levels. RESULTS: The baseline clinical characteristics of patients receiving IFX and RTX were similar. At the time of the second biopsy, 50% of patients had achieved a European League Against Rheumatism good or moderate response. At baseline, expression of CPB, C5a, and OPN was markedly higher in RA compared with OA synovium and correlated with mononuclear cell infiltration. There was an overall reduction in synovial expression of CPB, C5a, and OPN paralleling a reduction in mononuclear cell infiltration, but these changes were not associated with clinical response. After an early reduction in serum C5a levels, these returned to baseline levels at later timepoints. CONCLUSION: In response to IFX and RTX treatment, RA synovial expression of CPB, C5a, and OPN decrease independently of the clinical response, reflecting the complex proinflammatory and antiinflammatory effects of this pathway.