Target renal damage: the microvascular associations of increased aortic stiffness in patients with COPD

Correlation Analysis of Early Renal Injury in Elderly Patients with Acute Exacerbations of Chronic Obstructive Pulmonary Disease

Objective

To investigate the correlation between serum cystatin C (Cys-C) and beta-2 (β2) microglobulin (β2-MG) levels and renal injury in elderly patients with acute exacerbations of chronic obstructive pulmonary disease (AECOPD) with a view to detecting renal injury in its early stages.

Methods

A total of 106 patients with AECOPD were enrolled and divided into three groups according to their oxygen partial pressure (PO₂) levels: severe hypoxia group, moderate hypoxia group, and mild hypoxia group. Another 60 healthy subjects were selected as the control group. General clinical data were collected from all the study subjects, along with measurements of arterial blood gas, Cys-C, β2-MG, serum creatinine (Scr), urea nitrogen (BUN), partial pressure of carbon dioxide (PCO₂), and high-sensitivity C-reactive protein (hs-CRP).

Results

The levels of hs-CRP, Cys-C, β2-MG, Scr, and BUN were highest in the severe hypoxia group, followed by the moderate hypoxia group, then the mild hypoxia group, and lowest in the control group. The differences between the groups were statistically significant for these indicators (P < 0.05). Apart from in the cases of Scr and BUN, there were no statistically significant differences between the mild group and the control group (P > 0.05). The levels of Cys-C and β2-MG were positively correlated with the levels of hs-CRP, PCO₂, Scr, and BUN and negatively correlated with PO₂ levels. hs-CRP and PO₂ were high-risk factors influencing Cys-C levels, and β2-MG was a risk factor influencing Cys-C levels. The level of PO₂ was a high-risk factor influencing β2-MG levels, and PCO₂ and Cys-C were risk factors influencing β2-MG levels.

Conclusion

Renal injury was found to be present in patients with AECOPD and worsened with increasing degrees of hypoxia. Hypoxia and inflammation might be risk factors for renal injury in patients with AECOPD, Cys-C and β2-MG could be sensitive indicators for the early detection of renal injury.

COPD significantly increases cerebral and cardiovascular events in hypertensives

Essential hypertension and chronic obstructive pulmonary disease often coexist in the same patient. The aim of this study was to evaluate whether the addition of chronic obstructive pulmonary disease modifies the risk of cardiovascular events in hypertensives. We enrolled 1728 hypertensives. Study outcomes included fatal and non-fatal cardiovascular stroke and myocardial infarction, and cardiovascular death. During a mean follow-up of 57 months there were 205 major adverse cardiovascular events (2.47 per 100 pts/yr): cardiac (n117; 1.41 per 100 pts/yr) and cerebrovascular (n = 77; 0.93 per 100 pts/yr). In hypertensives with chronic obstructive pulmonary disease we observed a greater number of cardiovascular events than in hypertensives without respiratory disease (133 [5.55 per 100 pts/yr) vs 72 [1.22 per 100 pts/yr], respectively. The addition of chronic obstructive pulmonary disease to hypertension increased the incidence of total and non-fatal stroke of more than nine- (2.42 vs 0.32 per 100 pts/yr) and 11-fold (2.09 vs 0.22 per 100 pts/yr), respectively. The same trend was observed for total (2.88 vs 0.81 per 100 pts/yr) and non-fatal (2.67 vs 0.79 per 100 pts/y) myocardial infarction. The presence of chronic obstructive pulmonary disease in hypertensives significantly increases the risk of stroke, myocardial infarction and major adverse cardiovascular events.

When kidneys and lungs suffer together

A significant interaction between kidneys and lungs has been shown in physiological and pathological conditions. The two organs can both be targets of the same systemic disease (eg., some vasculitides). Moreover, loss of normal function of either of them can induce direct and indirect dysregulation of the other one. Subjects suffering from COPD may have systemic inflammation, hypoxemia, endothelial dysfunction, increased sympathetic activation and increased aortic stiffness. As well as the exposure to nicotine, all the foresaid factors can induce a microvascular damage, albuminuria, and a worsening of renal function. Renal failure in COPD can be unrecognized since elderly and frail patients may have normal serum creatinine concentration. Lungs and kidneys participate in maintaining the acid-base balance. Compensatory role of the lungs rapidly expresses through an increase or reduction of ventilation. Renal compensation usually requires a few days as it is achieved through changes in bicarbonate reabsorption. Chronic kidney disease and end-stage renal diseases increase the risk of pneumonia. Vaccination against Streptococcus pneumonia and seasonal influenza is recommended for these patients. Vaccines against the last very virulent H1N1 influenza A strain are also available and effective. Acute lung injury and acute kidney injury are frequent complications in critical illnesses, associated with high morbidity and mortality. The concomitant failure of kidneys and lungs implies a multidisciplinary approach, both in terms of diagnostic processes and therapeutic management.

Albuminuria in patients with chronic obstructive pulmonary disease: a cross-sectional study in an African patient cohort

Background

Cardiovascular disease (CVD) is remarkably frequent in patients with chronic obstructive pulmonary disease (COPD). Albuminuria is a marker of vascular endothelial dysfunction and predictor of CVD events. Albuminuria is prevalent in patients with COPD as it has been shown in Caucasian and Oriental populations with COPD. The objective of this study was to determine the prevalence of Albuminuria and COPD severity correlates among black patients with chronic obstructive pulmonary disease in order to see whether a similar trend of albuminuria is also prevalent in this population.

Methods

A total of 104 COPD patients were enrolled in the study. Lung functions were assessed by means of the Easy One™ spirometer. Albuminuria defined by urine albumin to creatinine ratio (ACR) was tested using CYBOW 12MAC microalbumin strips in a random spot urine collection. SPSS version 20 was used for data analysis.

Results

In the studied population, 25/104 (24%) patients had albuminuria and 16/104 (15.4%) patients had CVD. Abnormal urine albumin (Albuminuria and Proteinuria) was present in all patients with CVD. In the subset of 46 COPD patients assessed for severity, 60.9% (95%CIs 46.1–73.9) had moderate COPD and 30.4% (95% CIs, 17.9–49.0) severe COPD. Albuminuria was moderately significantly associated with COPD severity, p = 0.049; (0.049 < p < 0.05). Participants who ever smoked cigarettes had significantly likelihood of severe and very severe COPD (OR 11.5; 95% CIs, 1.3, 98.4) however, the significance was lost when adjusted for age and gender.

Conclusion

Albuminuria was prevalent in patients with COPD and it had a significant association with COPD severity.

A single gene connects stiffness in glaucoma and the vascular system

Arterial calcification results in arterial stiffness and higher systolic blood pressure. Arterial calcification is prevented by the high expression of the Matrix-Gla gene (MGP) in the vascular smooth muscle cells (VSMC) of the arteries' tunica media. Originally, MGP, a gene highly expressed in cartilage and VSMC, was found to be one of the top expressed genes in the trabecular meshwork. The creation of an Mgp-lacZ Knock-In mouse and the use of mouse genetics revealed that in the eye, Mgp's abundant expression is localized and restricted to glaucoma-associated tissues from the anterior and posterior segments. In particular, it is specifically expressed in the regions of the trabecular meshwork and of the peripapillary sclera that surrounds the optic nerve. Because stiffness in these tissues would significantly alter outflow facility and biomechanical scleral stress in the optic nerve head (ONH), we propose MGP as a strong candidate for the regulation of stiffness in glaucoma. MGP further illustrates the presence of a common function affecting key glaucomatous parameters in the front and back of the eye, and thus offers the possibility for a sole therapeutic target for the disease.

Study the association of chronic obstructive pulmonary disease with early endothelial dysfunction and its impact on cardiovascular system by estimating urinary albumin creatinine ratio

Background:

Chronic obstructive pulmonary disease (COPD) attribute to systemic inflammation which is responsible for microalbuminuria reflecting endothelial dysfunction, could be a significant surrogate marker of potential cardiovascular morbidity.

Objective:

The aim of our study was to find out the possible association of COPD with early cardiovascular changes in the form of renal endothelial dysfunction.

Settings and Design:

Case–control, multi-group, cross-sectional hospital-based study was designed and conducted in the Department of Respiratory Medicine of BPS Government Medical College for Women, Khanpur Kalan, Sonipat, Haryana.

Subjects and Methods:

The study included 150 subjects, comprising of three groups with each having 50 subjects: Group 1 – acute exacerbation of COPD, Group 2 – stable COPD patients, Group 3 – asymptomatic smokers. Pulmonary function test, urine albumin creatinine ratio (UACR) and brachio-ankle pulse wave velocity were measured in all the subjects.

Statistical Analysis:

Data were analyzed using SPSS ver 20 (IBM, USA) software. Continuous variables were compared by unpaired Student's t-test while correlation was measured by Pearson correlation test, P < 0.05 was considered statistically significant.

Results:

The mean urine albumin creatinine ratio UACR value in acute exacerbation of COPD (283.30 mg/g; standard deviation [SD] ±871.98) was found significantly higher compare to control subjects (24.17 mg/g; SD ± 32.105;) P = 0.038. Besides this COPD patients with Type 2 respiratory failure having robust positive correlation in between UACR and arterial blood pH (r = 0.559; P = 0.030) while it was inverse and moderate with partial pressure of arterial oxygen (r = −0.470; P = 0.077).

Conclusions:

Acute state of COPD with or without Type 2 respiratory failure is having a significant impact on cardiovascular system in the form of early microvascular changes.

Subclinical atherosclerosis risk markers in patients with chronic obstructive pulmonary disease: A systematic review and meta-analysis

BACKGROUND AND AIMS

Chronic obstructive pulmonary disease (COPD) is associated with increased cardiovascular morbidity and mortality. Identifying early changes of cardiovascular system before the occurrence of fatal clinical event is critical for the management of COPD. We performed a meta-analysis to investigate the associations between COPD and subclinical markers of cardiovascular risk.

METHODS

We searched PUBMED, EMBASE for studies published before Aug 1st, 2016, on the association between COPD and carotid intima-media thickness (CIMT), prevalence of carotid plaques, flow-mediated dilation (FMD), pulse-wave velocity (PWV) and augmentation index (AIx).

RESULTS

Thirty-two studies (3198 patients, 13867 controls) were included. Compared with controls, COPD patients had significantly higher CIMT (MD: 0.10 mm; 95% CI: 0.04, 0.16; p = 0.0007), PWV (SMD: 0.70; 95% CI: 0.52, 0.88; p < 0.0001), AIx (MD: 4.60%; 95% CI: 0.52, 8.68; p = 0.03), AIx@75 (AIx normalized to a heart rate of 75 beats per minute) (MD: 4.59%; 95% CI: 2.80, 6.38; p < 0.0001), prevalence of carotid plaque (OR: 2.54; 95% CI: 2.04, 3.15; p < 0.0001), and significantly lower FMD (MD: -4.21%; 95% CI: -6.71, -1.71; p = 0.001). Sensitivity and subgroups analyses substantially confirmed our results. Meta-regression analysis revealed that spirometry (as expressed by FEV₁%predicted) might influence on PWV.

CONCLUSIONS

These findings indicate that COPD, even in mild to moderate patients, had greater impaired markers of subclinical atherosclerosis and cardiovascular risk. However, further studies are still needed to address confounders, such as age, smoking, hypertension, diabetes etc, which might affect the associations in COPD patients.

Association between pulse wave velocity and a marker of renal tubular damage (N-acetyl-β-D-glucosaminidase) in patients without diabetes

The authors assessed the association between the ratio of urinary activity of N-acetyl-β-D-glucosaminidase (NAG) to creatinine and the brachial-ankle pulse wave velocity (baPWV) in patients without overt diabetes mellitus (DM). This was a cross-sectional study of 233 patients who had an estimated glomerular filtration rate (eGFR) ≥30 mL/min/1.73 m(2) and no history of kidney disease. Patients were divided into two groups: high NAG group (>5.8 U/g creatinine) and low NAG group (≤5.8 U/g creatinine). Mean baPWVs of the high NAG group were significantly higher than those of the low NAG group in both the eGFR ≥30 and <60 tertiles and the eGFR ≥60 and <90 tertiles. The baPWV was positively correlated with NAG in all patients (r=0.341, P<.001). Stepwise multivariate regression analysis showed that the baPWV was significantly related with NAG, age, and systolic blood pressure. Elevated NAG is related to elevated arterial stiffness in patients without DM.

Cardiovascular and inflammatory effects of simvastatin therapy in patients with COPD: a randomized controlled trial

Background

There is excess cardiovascular mortality in patients with chronic obstructive pulmonary disease. Aortic stiffness, an independent predictor of cardiovascular risk, and systemic and airway inflammation are increased in patients with the disease. Statins modulate aortic stiffness and have anti-inflammatory properties. A proof-of-principle, double-blind, randomized trial determined if 6 weeks of simvastatin 20 mg once daily reduced aortic stiffness and systemic and airway inflammation in patients with chronic obstructive pulmonary disease.

Methods

Stable patients (n=70) were randomized to simvastatin (active) or placebo. Pre-treatment and post-treatment aortic stiffness, blood pressure, spirometry, and circulating and airway inflammatory mediators and lipids were measured. A predefined subgroup analysis was performed where baseline aortic pulse wave velocity (PWV) was >10 m/sec.

Results

Total cholesterol dropped in the active group. There was no significant change in aortic PWV between the active group and the placebo group (−0.7 m/sec, P=0.24). In those with aortic stiffness >10 m/sec (n=22), aortic PWV improved in the active group compared with the placebo group (−2.8 m/sec, P=0.03). Neither systemic nor airway inflammatory markers changed.

Conclusion

There was a nonsignificant improvement in aortic PWV in those taking simvastatin 20 mg compared with placebo, but in those with higher baseline aortic stiffness (a higher risk group) a significant and clinically relevant reduction in PWV was shown.

Renal and hepatobiliary dysfunction in chronic obstructive pulmonary disease

PURPOSE OF REVIEW

This review examines the associations between chronic obstructive pulmonary disease (COPD) and renal and hepatobiliary diseases, with emphasis on the epidemiology and clinical outcomes, along with current information on pathophysiologic mechanisms and risk factors.

RECENT FINDINGS

Glomerular filtration, sodium retention, and waste excretion are abnormal in COPD and sensitive to hypoxemia and hypercarbia, but variably responsive to oxygen administration and angiotensin-converting enzyme inhibition. Newer concepts about the role of hypoxia on the progression of chronic renal failure, and improved understanding about the relationships between COPD, decreased arterial compliance, and renal glomerular injury, are bringing new insights about potential causal mechanisms between COPD and kidney diseases. Other than the well known relationship between cor pulmonale and passive liver congestion, little was known about the relationships between COPD and liver diseases until recent population-based surveys demonstrated that COPD patients have substantially elevated risk for specific hepatobiliary system diseases.

SUMMARY

Renal complications of COPD are common especially among patients with hypoxemia and hypercarbia. Renal-endocrine mechanisms, tissue hypoxia, and vascular rigidity have roles in the pathophysiology, but understanding of causal relationships is not precise. COPD patients have increased risk for hepatobiliary diseases and asymptomatic elevations of hepatic transaminases, which fortunately have relatively low prevalence.

Arterial stiffness in COPD

In patients with COPD, cardiovascular diseases are the most common concomitant chronic diseases, a leading cause of hospitalization, and one of the main causes of death. A close connection exists between COPD and cardiovascular diseases. Cardiovascular risk scores aim to predict the effect of cardiovascular comorbidities on COPD mortality, but there is a need to better characterize occult and suboccult cardiovascular disease, even in patients with mild to moderate COPD. Among various surrogate markers of cardiovascular risk, arterial stiffness plays a central role and is a strong independent predictor of cardiovascular events beyond classic cardiovascular risk factors. Its measurement is highly suitable, validated, and relatively easy to perform in routine COPD clinical practice. The growing awareness of the increased cardiovascular risk associated with COPD has led to a call for respiratory physicians to measure arterial pulse wave velocity in routine practice. Cross-sectional data establish elevated arterial stiffness as being independently linked to COPD. Candidate mechanisms have been proposed, but surprisingly, only limited data are available regarding the impact of the different COPD treatment modalities on arterial stiffness, although initial studies have suggested a significant positive impact. In this review, we present the various surrogate markers of cardiovascular morbidity in COPD and the central role of arterial stiffness and the underlying mechanisms explaining vascular remodeling in COPD. We also consider the therapeutic impact of COPD medications and exercise training on arterial stiffness and the assessments that should be implemented in COPD care and follow-up.