A Retrospective Analysis of Ventilatory Strategy Comparing Non-invasive Ventilation (NIV) With Invasive Ventilation in Patients Admitted With Severe COVID-19 Pneumonia.

Background The second wave of the COVID-19 pandemic in India saw a sudden upsurge of critically ill patients getting admitted to the ICU. The guidance for respiratory support was unclear in the early phase. But later reports showed lower mortality with non-invasive ventilation (NIV) than with intubation. The aim of this study was to assess the end result of initial methods of ventilation in COVID-19 patients. Methodology Patients admitted to ICU with COVID-19 were categorized as group 1 (IPPV-intubated within 24 hrs of admission), group 2 (NIV -NIV only), group 3 (NIV+ IPPV-intubated after 24 hrs), and group 4 (NRBM - Non-Rebreathing Mask only). All causes in the hospital or 30-day mortality, length of stay in ICU, and incidence of pneumothorax were compared between groups. Logistic regression analysis was done to determine the odds of mortality. Results The overall mortality rate among patients admitted to tertiary care centers was 15% and the rate among patients in ICU was 54.07%. Patients in group 1 and group 3 had significantly high mortality rates of 90.47% and 93.75%, respectively, as compared to 51.28% in group 2 patients. The odds of mortality were high in group 3 (OR 29.57, 95% CI 4.51 and 193.52) and group 1 (OR 8.01, 95% CI 1.35 and 47.48). Conclusion In a resource-limited setting, the use of NIV is associated with higher survival in COVID-19 patients. The prognosis of patients who are intubated early or after a trial of NIV is the same with increased odds of mortality.

Fogging of Protective Eyewear in Intensive Care Unit and a Comparative Study of Techniques to Reduce It.

Background: Fogging of protective eyewear (PEW) can hinder routine work in the intensive care unit (ICU). The prevalence of fogging impairing vision (FIV) and the technique that reduces fogging have not been evaluated previously. Methods: After donning personal protective equipment (PPE) with an N95 mask, the healthcare workers (HCWs) sequentially tried plain PEW, soap-coated PEW, PEW worn at a distance over the PPE hood, and the use of tape over a mask. The vision (distant and near) was checked before wearing PEW and with each technique. The prevalence of fogging and FIV, that is, change in vision in either eye was estimated and compared among various techniques. Mixed-effects logistic regression was used to analyze factors affecting fogging and to compare techniques. Room temperature, room humidity, and lens temperature were measured during the study. Results: A total of 125 HCWs participated (151 observations) and the prevalence of FIV was 66.7%. The fogging of PEW, as well as the extent of PEW fogging, was least with soap coating followed by a mask with tape and goggles worn at a distance. The FIV was significantly lesser only with the mask with tape with an odds ratio (OR) [confidence interval CI)] of 0.45 (0.25-0.82). The prevalence of fogging while at work in the COVID ICU was 38%. Conclusion: The prevalence of FIV is 66%. Application of tape over the mask can avoid disturbances in vision best. Soap coating of the PEW and PEW worn at distance from the eyes are potential alternatives. How to cite this article: Ravisankar NP, D'Silva CS, Varma MMKG, Sudarsan TI, Sampath S, Thomas T, et al. Fogging of Protective Eyewear in Intensive Care Unit and a Comparative Study of Techniques to Reduce It. Indian J Crit Care Med 2023;27(1):32-37.

Early postoperative complications in lung transplant recipients.

Lung transplantation has become an established therapy for end-stage lung diseases. Early postoperative complications can impact immediate, mid-term, and long-term outcomes. Appropriate management, prevention, and early detection of these early postoperative complications can improve the overall transplant course. In this review, we highlight the incidence, detection, and management of these early postoperative complications in lung transplant recipients.

Antioxidant micronutrient supplementation in critically ill adults: A systematic review with meta-analysis and trial sequential analysis.

BACKGROUND: The role of antioxidant micronutrient (AxM) supplementation in the critically ill patients has been controversial, and recent trials have suggested a tendency to harm. Therefore, we performed a systematic review with meta-analysis and trial sequential analysis (TSA) of randomized controlled trials (RCT) to examine the effect of AxM supplementation on clinical outcomes among critically ill adults. METHODS: PubMed, EMBASE, Cochrane, CINAHL, LILACS, DARE, SCOPUS, and Web of sciences databases were searched from inception to March 2019. RCTs that compared AxM supplements with placebo in adult critically ill patients and reporting mortality as an outcomes were included. Trial quality was assessed using updated cochrane risk of bias (RoB-II) tool. Primary outcome was all-cause mortality. Secondary outcomes were 28-day mortality, intensive care unit (ICU) and hospital length of stay (LOS), ventilator days and infection between the two groups. Outcomes were summarised using random-effects estimators. Quality of evidence (QOE) was rated using Grading of Recommendations, Assessment, Development and Evaluation. Prior to final analysis, we repeated the search through September 2019. R version 3.6.2 and STATA version 13 were used for all statistical analyses. RESULTS: Pooled analysis of 34 trials with 4678 patients revealed that AxM supplementation was associated with possible reduction in all-cause mortality (relative risk [RR], 0.89 [95%CI 0.79 to 0.99], TSA adjusted CI 0.77 to 1.03; Low QOE). Fragility index and number needed to treat were 1 and 41, respectively. Eight studies with low RoB (RR, 1.08; 95%CI 0.95 to 1.23; TSA CI, 0.64 to 1.82; moderate QOE) did not show mortality reduction with AxM supplementation. SECONDARY OUTCOMES: ICU LOS (weighted mean difference [WMD], -0.84; 95%CI -1.50 to -0.18; moderate QOE), hospitalization days (WMD, -2.83; 95%CI -3.91to -1.75; low QOE) and ventilator days (WMD, -1.87; 95%CI -3.60 to -0.14; very low QOE) showed a statistically significant benefit with AxM supplementation. In meta-regression analysis, neither the duration of AxM therapy nor the dosage of selenium, which was the most widely studied AxM, reported an association with mortality. CONCLUSION: Although AxM supplementation was associated with possible reduction in all-cause mortality, results from the TSA and studies with low RoB showing null effect suggest that the evidence of benefit is questionable. Secondary outcomes attained statistically significant benefit with AxM supplements, but the certainity of evidence was low. To summarize, current evidence does not justify administration of AxM in critically ill patients. REGISTRATION: PROSPERO, CRD42019125898.

Increasing Medical Student Interest in Nephrology.

BACKGROUND: Interest in nephrology careers is declining, possibly due to perceptions of the field and/or training aspects. Understanding practices of medical schools successfully instilling nephrology interest could inform efforts to attract leading candidates to the specialty. METHODS: The American Society of Nephrology Workforce Committee's Best Practices Project was one of several initiatives to increase nephrology career interest. Board-certified nephrologists graduating medical school between 2002 and 2009 were identified in the American Medical Association Masterfile and their medical schools ranked by production. Renal educators from the top 10 producing institutions participated in directed focus groups inquiring about key factors in creating nephrology career interest, including aspects of their renal courses, clinical rotations, research activities, and faculty interactions. Thematic content analysis of the transcripts (with inductive reasoning implementing grounded theory) was performed to identify factors contributing to their programs' success. RESULTS: The 10 schools identified were geographically representative, with similar proportions of graduates choosing internal medicine (mean 26%) as the national graduating class (26% in the 2017 residency Match). Eighteen educators from 9 of these 10 institutions participated. Four major themes were identified contributing to these schools' success: (1) nephrology faculty interaction with medical students; (2) clinical exposure to nephrology and clinical relevance of renal pathophysiology materials; (3) use of novel educational modalities; and (4) exposure, in particular early exposure, to the breadth of nephrology practice. CONCLUSION: Early and consistent exposure to a range of clinical nephrology experiences and nephrology faculty contact with medical students are important to help generate interest in the specialty.

Does Academic Blogging Enhance Promotion and Tenure? A Survey of US and Canadian Medicine and Pediatric Department Chairs.

BACKGROUND: Electronic educational (e-learning) technology usage continues to grow. Many medical journals operate companion blogs (an application of e-learning technology) that enable rapid dissemination of scientific knowledge and discourse. Faculty members participating in promotion and tenure academic tracks spend valuable time and effort contributing, editing, and directing these medical journal blogs. OBJECTIVE: We sought to understand whether chairs of medicine and pediatric departments acknowledge blog authorship as academic achievement. METHODS: The authors surveyed 267 chairs of US and Canadian medicine and pediatric departments regarding their attitudes toward the role of faculty participation in e-learning and blogging in the promotion and tenure process. The survey completion rate was 22.8% (61/267). RESULTS: A majority of respondents (87%, 53/61) viewed educational scholarship as either important or very important for promotion. However, only 23% (14/61) perceived importance to faculty effort in producing content for journal-based blogs. If faculty were to participate in blog authorship, 72% (44/61) of surveyed chairs favored involvement in a journal-based versus a society-based or a personal (nonaffiliated) blog. We identified a "favorable group" of chairs (19/59, 32%), who rated leadership roles in e-learning tools as important or very important, and an "unfavorable group" of chairs (40/59, 68%), who rated leadership roles in e-learning tools as somewhat important or not important. The favorable group were more likely to be aware of faculty bloggers within their departments (58%, 11/19 vs 25%, 10/40), viewed serving on editorial boards of e-learning tools more favorably (79%, 15/19 vs 31%, 12/39), and were more likely to value effort spent contributing to journal-based blogs (53%, 10/19 vs 10%, 4/40). CONCLUSIONS: Our findings demonstrate that although the majority of department chairs value educational scholarship, only a minority perceive value in faculty blogging effort.

Angiographic characteristics of coronary arterial segments progressing to myocardial infarction in patients with and without chronic kidney disease.

BACKGROUND: Individuals with chronic kidney disease (CKD) have high rates of myocardial infarction (MI), but whether the nature of coronary lesions susceptible to plaque rupture is altered and whether the high rate of MI is related to a greater burden of atherosclerotic lesions in individuals with CKD is uncertain. METHODS: We used quantitative coronary angiography to assess atherosclerotic plaque location and characteristics at baseline and at the time of MI in 62 patients with and without CKD. Univariate and multivariable conditional logistic regression models were used to assess whether the association between pre-MI angiographic findings and MI differs in individuals with and without CKD. RESULTS: The risk of MI rose as the distance from the coronary ostium decreased both in patients with CKD (odds ratio per 10 mm 0.92 [95 % CI 0.87-0.99]) and in those without CKD (odds ratio 0.83 [95 % CI 0.75-0.93]). Although tighter degrees of coronary stenosis were associated with increased risks of MI in patients with and without CKD, the majority of MIs (70.9 % in patients with CKD and 89.5 % in those without CKD) occurred in segments with <50 % diameter stenosis at baseline. CONCLUSIONS: The characteristics of lesions progressing to MI are similar in individuals with and without CKD and the majority of events occur in areas with <50 % stenosis at baseline. Given the high burden of non-stenotic lesions in patients with CKD, an interventional strategy aimed solely at sites with high-grade stenosis is unlikely to markedly reduce the risk of MI in patients with CKD.

Long-term clinical outcomes following drug-eluting or bare-metal stent placement in patients with severely reduced GFR: Results of the Massachusetts Data Analysis Center (Mass-DAC) State Registry.

BACKGROUND: Patients with chronic kidney disease have been under-represented in randomized trials of drug-eluting stents relative to bare-metal stents and are at high risk of mortality. STUDY DESIGN: Cohort study with propensity score matching. SETTINGS & PARTICIPANTS: All adults with chronic kidney disease and severely decreased glomerular filtration rate (GFR; serum creatinine >2.0 mg/dL or dialysis dependence) undergoing percutaneous coronary intervention with stent placement between April 1, 2003, and September 30, 2005, at all acute-care nonfederal hospitals in Massachusetts. PREDICTOR: Patients were classified as drug-eluting stent-treated if all stents were drug eluting and bare-metal stent-treated if all stents were bare metal. Patients treated with both types of stents were excluded from the primary analysis. OUTCOMES & MEASUREMENTS: 2-year crude mortality risk differences (drug-eluting - bare-metal stents) were determined from vital statistics records, and risk-adjusted mortality, myocardial infraction (MI), and revascularization differences were estimated using propensity score matching of patients with severely reduced GFR based on clinical and procedural information collected at the index admission. RESULTS: 1,749 patients with severely reduced GFR (24% dialysis dependent) were treated with drug-eluting (n = 1,256) or bare-metal stents (n = 493) during the study. Overall 2-year mortality was 32.8% (unadjusted drug-eluting stent vs bare-metal stent; 30.1% vs 39.8%; P < 0.001). After propensity score matching 431 patients with a drug-eluting stent to 431 patients with a bare-metal stent, 2-year risk-adjusted mortality, MI, and target-vessel revascularization rates were 39.4% versus 37.4% (risk difference, 2.1%; 95% CI, -4.3 to 8.5; P = 0.5), 16.0% versus 19.0% (risk difference, -3.0%; 95% CI, -8.2 to 2.1; P = 0.3), and 13.0% versus 17.6% (risk difference, -4.6%; 95% CI, -9.5 to 0.3; P = 0.06). LIMITATIONS: Observational design, ascertainment of serum creatinine level >2.0 mg/dL and dialysis dependence from case report forms. CONCLUSIONS: In patients with severely decreased GFR, treatment with drug-eluting stents was associated with a modest decrease in target-vessel revascularization not reaching statistical significance and was not associated with a difference in risk-adjusted rates of mortality or MI at 2 years compared with bare-metal stents.

Drug-eluting or bare-metal stenting in patients with diabetes mellitus: results from the Massachusetts Data Analysis Center Registry.

BACKGROUND: Patients with diabetes mellitus (DM) are at high risk for restenosis, myocardial infarction, and cardiac mortality after coronary stenting, and the long-term safety of drug-eluting stents (DES) relative to bare-metal stents (BMS) in DM is uncertain. We report on a large consecutive series of patients with DM followed up for 3 years after DES and BMS from a regional contemporary US practice with mandatory reporting. METHODS AND RESULTS: All adults with DM undergoing percutaneous coronary intervention with stenting between April 1, 2003, and September 30, 2004, at all acute care nonfederal hospitals in Massachusetts were identified from a mandatory state database. According to index admission stent type, patients were classified as DES treated if all stents were drug eluting and as BMS treated if all stents were bare metal; patients treated with both types of stents were excluded from the primary analysis. Mortality rates were obtained from vital statistics records, and myocardial infarction and revascularization rates were obtained from the state database with complete 3 years of follow-up on the entire cohort. Risk-adjusted mortality, myocardial infarction, and revascularization differences (DES-BMS) were estimated with propensity-score matching based on clinical, procedural, hospital, and insurance information collected at the index admission. DM was present in 5051 patients (29% of the population) treated with DES or BMS during the study. Patients with DM were more likely to receive DES than BMS (66.1% versus 33.9%; P<0.001). The unadjusted cumulative incidence of mortality at 3 years was 14.4% in DES versus 22.2% in BMS (P<0.001). Based on propensity-score analysis of 1:1 matched DES versus BMS patients (1476 DES:1476 BMS), the risk-adjusted mortality, MI, and target vessel revascularization rates at 3 years were 17.5% versus 20.7% (risk difference, -3.2%; 95% confidence interval, -6.0 to -0.4; P=0.02), 13.8% versus 16.9% (-3.0%; 95% confidence interval, -5.6 to 0.5; P=0.02), and 18.4% versus 23.7% (-5.4%; confidence interval, -8.3 to -2.4; P<0.001), respectively. CONCLUSIONS: In a real-world diabetic patient population with mandatory reporting and follow-up, DES were associated with reduced mortality, myocardial infarction, and revascularization rates at long-term follow-up compared with BMS.

Drug-eluting or bare-metal stents for acute myocardial infarction.

BACKGROUND: Studies comparing percutaneous coronary intervention (PCI) with drug-eluting and bare-metal coronary stents in acute myocardial infarction have been limited in size and duration. METHODS: We identified all adults undergoing PCI with stenting for acute myocardial infarction between April 1, 2003, and September 30, 2004, at any acute care, nonfederal hospital in Massachusetts with the use of a state-mandated database of PCI procedures. We performed propensity-score matching on three groups of patients: all patients with acute myocardial infarction, all those with acute myocardial infarction with ST-segment elevation, and all those with acute myocardial infarction without ST-segment elevation. Propensity-score analyses were based on clinical, procedural, hospital, and insurance information collected at the time of the index procedure. Differences in the risk of death between patients receiving drug-eluting stents and those receiving bare-metal stents were determined from vital-statistics records. RESULTS: A total of 7217 patients were treated for acute myocardial infarction (4016 with drug-eluting stents and 3201 with bare-metal stents). According to analysis of matched pairs, the 2-year, risk-adjusted mortality rates were lower for drug-eluting stents than for bare-metal stents among all patients with myocardial infarction (10.7% vs. 12.8%, P=0.02), among patients with myocardial infarction with ST-segment elevation (8.5% vs. 11.6%, P=0.008), and among patients with myocardial infarction without ST-segment elevation (12.8% vs. 15.6%, P=0.04). The 2-year, risk-adjusted rates of recurrent myocardial infarction were reduced in patients with myocardial infarction without ST-segment elevation who were treated with drug-eluting stents, and repeat revascularization rates were significantly reduced with the use of drug-eluting stents as compared with bare-metal stents in all groups. CONCLUSIONS: In patients presenting with acute myocardial infarction, treatment with drug-eluting stents is associated with decreased 2-year mortality rates and a reduction in the need for repeat revascularization procedures as compared with treatment with bare-metal stents.

Controlling the ABCs of diabetes in clinical practice: a community-based endocrinology practice experience.

AIMS: Determine A1C, blood pressure (BP), and total cholesterol (TC) (Diabetes ABCs) control in a community-based endocrinology practice (CBEP) and compare levels to national averages. Additionally, determine patient factors associated with ABC control. METHODS: A retrospective chart audit of 395 consecutive patients seen for diabetes management was conducted for years 2000-2004 to examine levels of control of the ABCs. Multivariate models were used to determine patient factors associated with control. RESULTS: Significantly more patients met the goal of A1C <7% in the CBEP compared to national estimates (CBEP: 47.1% vs. NHANES 1999-2000: 37%, p=0.003). Similar patterns were observed for BP (CBEP: 53.2% vs. NHANES 1999-2000: 35.8%, p<0.0001), TC (CBEP: 82% vs. NHANES 1999-2000: 48.2%, p<0.0001), and all three ABCs (CBEP: 22%, vs. NHANES 1999-2000: 7.3%, p<0.0001). The proportion of patients meeting all three ABC goals in the CBEP increased significantly over time (p<0.0001). Multivariate models demonstrated that patients not needing insulin (p<0.0001), and taking fewer BP (p<0.0001), and cholesterol-lowering medications (p<0.02) were significantly more likely to have ABCs in control. CONCLUSIONS: Attainment of ABC goals is feasible in a CBEP and can be achieved at rates higher than national averages. Attention to factors that affect these goals is warranted.

Fibrotic injury after experimental deep vein thrombosis is determined by the mechanism of thrombogenesis.

Vessel wall matrix changes occur after injury, although this has not been well studied in the venous system. This study tested the hypothesis that the thrombus dictates the vein wall response and vein wall damage is directly related to the duration of thrombus contact. To determine the injury response over time, rats underwent inferior vena cava (IVC) ligation to produce a stasis thrombus, with harvest at various time points to 28 days (d). Significant vein wall matrix changes occurred with biomechanical injury (stiffness) peaking at 7-14 d, with concurrent early reduction in total collagen, an increase in early matrix metalloproteinase (MMP)-9 and late MMP-2, and concomitant increase in tumor necrosis factor (TNF)alpha, monocyte chemoattractant(MCP)-1 and tumor growth factor (TGF)beta (all P<0.05). To isolate the effect of the thrombus and its mechanism of genesis, rats underwent 7 d or limited stasis (24 hours), non-stasis thrombosis, or non-thrombotic IVC occlusion (Silicone plug). Vein wall stiffness was increased seven-fold, with a five-fold reduction in collagen, and 5.5- to seven-fold increase in TNFalpha, MCP-1, and TGFbeta with 7 d stasis as compared with controls (all P<0.05). By Picosirus red staining analysis, collagenolysis was significantly greater with 7 d stasis injury (P=0.01) but neither MMP-9 nor MMP-2 activity correlated with injury mechanism. In addition, vein wall cellular proliferation and uPA gene expression paralled the stasis thrombotic injury. Limited stasis, non-stasis thrombosis and non-thrombotic IVC occlusion showed a lesser inflammatory response. These data suggest both a static component and the thrombus directs vein wall injury via multiple mechanisms.

Proximate versus nonproximate risk factor associated primary deep venous thrombosis: clinical spectrum and outcomes.

OBJECTIVE: Although the treatment for acute deep vein thrombosis (DVT) is uniform, the circumstances under which it develops vary widely and may impact outcomes. This study compared clinical features and outcomes in patients who developed a primary DVT associated with a defined risk to those without any proximate risk factor. METHODS: Consecutive patients with a primary DVT and no past venous thromboembolism history from 2000 to 2002 were abstracted for demographics, risk factors, DVT anatomical characteristics, treatment, and outcomes of death and new pulmonary embolism. Comparison between patients with a proximate risk event within 30 days of DVT (Inpt) and those presenting with DVT with no defined proximate event (Outpt) was done by univariable and multivariable statistics. A validated survey was mailed to all living patients to assess long-term sequela. RESULTS: A total of 293 patients with a mean age of 55 years and 49% men had confirmed DVT by objective means (92% duplex) with a mean follow-up of 25 +/- 21 months. Inpts were more likely to have recent surgery or blunt trauma, bilateral DVT, less use of low molecular weight heparin (LMWH), and new pulmonary emboli (all P <.05). Outpts with DVT were more likely to have a history of malignancy, tibial-popliteal DVT compared with iliofemoral DVT, higher use of LMWH, and coumadin. However, there was no difference in mortality. From the patient survey (21% response), Outpts were more likely than Inpts to develop later varicosities and have daily frustration related to their legs (P < .05), but no difference in edema or ulceration. Considering the entire group, independent factors associated with freedom from PE included ambulation (odds ratio [OR] = 2.3; 95% confidence interval [CI] = 1.1-5.0; P = .04) while bilateral DVT (OR = .26; 95% CI = .09-.76; P = .013) or subcutaneous heparin (OR = 22; 95% CI = .05-.98; P = .047) were associated with greater risk. Independent factors associated with survival included ambulation (OR = 3.0; 95% CI = 1.3-7.2; P = .02), Coumadin use (OR = 2.7; 95% CI = 1.2-6.1; P = .015), and tibiopopliteal DVT (OR = 2.4; 95% = 1.1-5.5; P = .03), while malignancy (OR = 0.1; 95% CI = .05-.24; P < .01) and myocardial infarction (OR = 0.12; 95% CI = .01-.92; P = .04) were associated with lower survival. CONCLUSION: Patients who develop DVT related to a defined proximate risk event (Inpt) generally have more extensive DVT, an increased risk of PE, but less long-term functional morbidity and no difference in long-term mortality compared to those with no proximate risk.

Targeted deletion of CCR2 impairs deep vein thombosis resolution in a mouse model.

CCR2 is required for monocyte recruitment in many inflammatory processes, as well as conferring Th1 lymphokine responses. Deep vein thrombosis (DVT) resolution represents a specific inflammatory response whereby the thrombus must be dissolved for restoration of blood flow. Using a stasis model of DVT in the mouse, we investigated the role of CCR2 on DVT resolution. Genetic deletion of CCR2 (CCR2-/-) was associated with larger thrombi at early and later time points, increased thrombus collagen, fewer thrombus monocytes (F4/80), and significantly impaired neovascularization. IL-2 and IFN-gamma were significantly reduced in early CCR2-/- thrombi, whereas MCP-1 was significantly increased, and Th2 lymphokines were unaffected. Supplementation of CCR2-/- mice with IFN-gamma normalized early thrombus resolution without increasing monocyte influx. Neither Ab depletion of IFN-gamma nor genetic deletion of IFN-gamma impaired early DVT resolution. Early fibrinolysis was not impaired in CCR2-/- mice, but a significant reduction in both matrix metalloproteinase (MMP)-2 and MMP-9 activity was observed. However, only MMP-9 activity was restored with administration of IFN-gamma. We conclude that an early CCR2-dependent Th1 lymphokine response predominates in normal DVT resolution, mediates this in part by MMP-9 activation, but is not solely dependent on IFN-gamma.

Neutrophils modulate post-thrombotic vein wall remodeling but not thrombus neovascularization.

Early deep venous thrombosis (DVT) resolution is associated with neutrophil (PMN) influx. This study examined the role of PMNs in thrombus neovascularization and vein wall injury after DVT. A rat model of DVT by inferior vena cava (IVC) ligation was performed with control serum or rabbit anti-rat PMN serum administered perioperatively with sacrifice at 2 and 7 days. At 2 days, neutropenic rats had 1.6-fold larger thrombi (P = .04) and 1.4-fold higher femoral venous pressures by water manometry (P = .008) but no difference in thrombus neovascularization was observed. By 7 days, DVT sizes were similar, but vein wall injury persisted in the neutropenic rats with a 2.0-fold increase in vein wall stiffness by microtensiometry (P < .05), as well as a 1.2-fold increased thickness (P = .04). Collagen and profibrotic growth factors were significantly increased in neutropenic IVC at 7 days (all P < .05). Vein wall and intrathrombus uPA byWestern immunoblotting, and intrathrombus MMP-9 gelatinase activity were significantly less in neutropenic rats than controls (P < .001). Conversely, MMP-2 was significantly elevated in neutropenic IVC at 2 days after DVT. However, neutropenia induced 24 hours after DVT formation resulted in no significant increase in vein wall stiffness or collagen levels at 7 days, despite 1.4-fold larger thrombi (P < .05). These data suggest a critical early role for PMN in post DVT vein wall remodeling.

Vein wall remodeling after deep vein thrombosis involves matrix metalloproteinases and late fibrosis in a mouse model.

HYPOTHESIS: Deep venous thrombosis (DVT) confers vein wall injury associated with fibrosis and extracellular matrix (ECM) turnover, likely mediated by matrix proteases. This study investigated the expression of proteases and collagen involved in early vein wall remodeling. METHODS: In the mouse, DVT was produced by ligation of the infrarenal inferior vena cava (IVC) or sham operation, and tissue was harvested at 4, 8, and 12 days. The vein wall tissue was processed for real-time reverse transcriptase-polymerase chain reaction (6 to 8 per time point), Western immunoblotting (5 per time point), and gelatin zymography (5 per time point). Analysis of variance was used for multiple comparisons, and a P < .05 was significant. RESULTS: Thrombus resolution was documented by a 38% decrease in the thrombosed IVC weight from day 4 to day 12 (P = .007). Total vein wall collagen increased over time, with a corresponding increase in procollagen I and III, and expression peaked at 12 days (24-fold and 6.1-fold, respectively, P < .02). Matrix metalloproteinase-2 (MMP-2) gene expression was 23-fold greater at 12 days after thrombus formation compared with sham or 4 days after thrombosis (P < .05). Total MMP-2 activity was also significantly elevated at 12 days compared with sham (P < .05). MMP-9 expression was 19-fold and 27-fold higher at days 4 and 8, respectively, relative to sham (P < .05), with no difference in activity. MMP-14 expression was twofold to 3.6-fold greater at day 12 compared with earlier time points and shams (P < .001), but no differences in protein levels were found. Urokinase-type plasminogen activator (uPA) and plasminogen activator inhibitor-1 (PAI-1) protein levels were not significantly different from sham over time; however, the ratio of uPA to PAI-1 was decreased through 8 days. CONCLUSIONS: Vein wall remodeling after DVT is similar to wound healing and is associated with increased procollagen gene expression and total collagen. It is also associated with increased early MMP-9 expression, followed by MMP-2 expression and activity after DVT resolution. CLINICAL RELEVANCE: Deep vein thrombosis is an often neglected problem that long term is associated with the postphlebitic syndrome of limb swelling, pain, and often ulceration. The basic mechanisms of the vein wall damage that results have not been delineated. The following study describes the vein wall matrix metalloproteinase gene and activity response induced over time in the vein wall after DVT. Additionally, the corresponding collagen upregulation and proximate plasmin system mediators are determined. With this knowledge, potential therapies to reduce vein wall injury directly might be possible.

Deep vein thrombosis resolution is not accelerated with increased neovascularization.

INTRODUCTION: Deep venous thrombosis (DVT) resolution involves fibrinolysis, neovascularization, and fibrosis. We hypothesized that promoting neovascularization would accelerate DVT resolution. METHODS: A rat model of stasis DVT was produced with proximal ligation of the inferior vena cava (IVC) and all visible tributaries. One microg of interferon inducible protein (IP-10; angiostatic chemokine), basic fibroblast growth factor (bFGF; pro-angiogenic cytokine), epithelial neutrophil activating protein (ENA-78; pro-angiogenic chemokine), or saline solution control was injected into the IVC after ligation, and then via tail vein injection daily until sacrifice at either 4 or 8 days. Peripheral blood counts were measured, and thrombus weight was recorded at sacrifice. Laser Doppler in vivo imaging was used to estimate post-thrombotic IVC blood flow. Immunohistologic assessment of the thrombosed IVC for polymorphonuclear neutrophils (PMNs), monocytes (ED-1), and laminin (neovascular channels) was performed or the thrombus was separated from the IVC and assayed for keratinocyte cytokine (KC), monocyte chemotactic protein-1 (MCP-1), bFGF with enzyme-linked immunosorbent assay (ELISA), and total collagen with a direct colorimetric assay. RESULTS: Peripheral blood and intrathrombus PMNs and monocytes were not significantly different in the treated or control rats. There were no differences in any measure at 4 days. At 8 days, thrombus neovascularity, but not weight or collagen content, was increased in rats treated with bFGF or ENA-78 compared with control rats (17.6 +/- 0.93, 16.2 +/- 0.97 vs 13.2 +/- 0.79; channels/5 high-power fields (hpf; n = 6-10; P <.05). Post DVT IVC blood flow was significantly increased in bFGF-treated rats but not in rats treated with IP-10 or ENA-78, as compared with control rats. Rats treated with ENA-78 had increased intrathrombus bFGF compared with control rats (85 +/- 27 pg/mg protein vs 20 +/- 6 pg/mg protein; n = 6; P <.05), but other mediators were not significantly different in treated rats compared with control rats. CONCLUSION: Pro-angiogenic compounds increase thrombus neovascularization, but this does not correlate with smaller or less fibrotic DVT. Mechanisms other than neovascularization may be more important to hasten DVT dissolution. Clinical relevance Improved therapy for deep venous thrombosis (DVT) will ideally increase the rate of thrombus dissolution and eliminate the bleeding risks of anticoagulation. This study evaluated promoting DVT neovascularization with angiogenic chemokines, and, while successful by experimental measures, this did not translate into smaller DVT. Solely promoting thrombus neovascularization will not likely speed resolution.

Neutropenia impairs venous thrombosis resolution in the rat.

OBJECTIVES: Neutrophil influx is one of the first events in a formed deep venous thrombosis (DVT), but whether these cells are active participants in the resolution process is not clear. This study tests the hypothesis that neutrophils (PMN) are active participants in DVT resolution. METHODS: Thrombosis was induced by inferior vena caval (IVC) ligation in male Sprague-Dawley rats, and rats were sacrificed at 2, 4, or 7 days for evaluation of the thrombus. Neutropenia was induced by rabbit anti-rat PMN serum, and controls received rabbit serum. Venography was performed at the 7-day time point. Immunohistochemical staining was performed to quantify intrathrombus PMNs and monocytes, and the myeloperoxidase (MPO) assay was performed to assess intrathrombus neutrophil activity. Intrathrombus concentrations of kerotinocyte cytokine (KC), macrophage inflammatory protein-2 (MIP-2), gamma interferon inducible protein-10 (IP-10), macrophage inflammatory protein-1 alpha (MIP-1 alpha), monocyte chemoattractant protein-1 (MCP-1), and tumor necrosis factor (TNF)-alpha were quantified by enzyme immunoassay at each time point and normalized to total protein. Total collagen was determined at day 7. RESULTS: Peripheral blood smears showed a 94% PMN reduction at 2 days (P <.05), recovering to 44% of control at 7 days. Intrathrombus PMNs were significantly lower in neutropenic rats at 2 and 4 days, but there were no differences in intrathrombus monocytes. The MPO assay confirmed reduced neutrophil activity at 4 days. Thrombi from neutropenic rats were larger at 2 and 7 days compared with controls. In vivo thrombus area at 7 days as assessed by venography was also greater in neutropenic rats as compared with controls. The intrathrombus KC concentration was increased more than 20-fold in the neutropenic rats at 2 days, but there were no significant differences in other intrathrombus chemokines. Finally, intrathrombus collagen was increased over threefold in neutropenic rats as compared with controls. CONCLUSION: Neutropenia impairs DVT resolution by several measures, most likely by altering normal fibrinolytic activity and thrombus collagen turnover.