Endothelial cell activity in chronic obstructive pulmonary disease without severe pulmonary hypertension

A double blind randomized placebo control crossover trial on the effect of dietary nitrate supplementation on exercise tolerance in stable moderate chronic obstructive pulmonary disease

BACKGROUND

Dietary nitrate supplementation has been shown to decrease the oxygen cost of exercise and prolong exercise tolerance, as measured by sub-maximal exercise endurance distance and time at 85% V̇O2max, in both elite athletes and normal healthy subjects. Patients with chronic obstructive pulmonary disease (COPD) have reduced quality of life and ability to perform activities of daily living attributable to diminished exercise tolerance, and dietary nitrate may be able to ameliorate this.

METHODS

We performed a double-blind, computer-randomized placebo control crossover trial at a tertiary Australian hospital to investigate whether dietary nitrate supplementation as beetroot juice (BR) would augment submaximal exercise endurance in individuals with spirometrically confirmed stable moderate COPD. Volunteers underwent an incremental shuttle walk test to determine V̇O2max followed by a test dose of BR to establish safety in the study population. Participants performed an endurance shuttle walk test (ESWT) at 85% V̇O2max after randomization to either a 3 day wash-in of BR (4.8 mmol twice a day) or placebo (nitrate deplete BR), with a final dose on the morning of testing. They then crossed over after 4 day washout. Repeated measures two sided paired t-tests were employed.

RESULTS

35 participants were recruited with 19 completing the trial. In the initial safety phase, we measured systolic blood pressure over four hours post first dose of BR, and found a mean 10 mmHg decrement maximal at 1 hour. One individual developed symptomatic postural hypotension and was excluded. The primary outcomes of ESWT distance and time to fatigue improved by 11% and 6% respectively; however these differences did not achieve statistical significance (p = 0.494 and 0.693 respectively).

CONCLUSIONS

Our study does not support a role for routine dietary nitrate supplementation for enhancement of exercise endurance in COPD.

TRIAL REGISTRATION

Australia and New Zealand Clinical Trial Register: ACTRN12611001088932.

The VICI-trial: high frequency oscillation versus conventional mechanical ventilation in newborns with congenital diaphragmatic hernia: an international multicentre randomized controlled trial

BACKGROUND

Congenital diaphragmatic hernia (CDH) is a severe congenital anomaly of the diaphragm resulting in pulmonary hypoplasia and pulmonary hypertension. It is associated with a high risk of mortality and pulmonary morbidity. Previous retrospective studies have reported high frequency oscillatory ventilation (HFO) to reduce pulmonary morbidity in infants with CDH, while others indicated HFO to be associated with worse outcome. We therefore aimed to develop a randomized controlled trial to compare initial ventilatory treatment with high-frequency oscillation and conventional ventilation in infants with CDH.

METHODS/DESIGN

This trial is designed as a multicentre trial in which 400 infants (200 in each arm) will be included. Primary outcome measures are BPD, described as oxygen dependency by day 28 according to the definition of Jobe and Bancalari, and/or mortality by day 28. All liveborn infants with CDH born at a gestational age of over 34 weeks and no other severe congenital anomalies are eligible for inclusion. Parental informed consent is asked antenatally and the allocated ventilation mode starts within two hours after birth. Laboratory samples of blood, urine and tracheal aspirate are taken at the first day of life, day 3, day 7, day 14 and day 28 to evaluate laboratory markers for ventilator-induced lung injury and pulmonary hypertension.

DISCUSSION

To date, randomized clinical trials are lacking in the field of CDH. The VICI-trial, as the first randomized clinical trial in the field of CDH, may provide further insight in ventilation strategies in CDH patient. This may hopefully prevent mortality and morbidity.

TRIAL REGISTRATION

Netherlands Trial Register (NTR): NTR1310.

Thrombin generation in chronic obstructive pulmonary disease: dependence on plasma factor composition

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is associated with an increased risk for thromboembolic events. We investigated thrombin generation profiles in COPD patients and their dependence on plasma factor/inhibitor composition.

METHODS

Factors (f) (fII, fV, fVII, fVIII, fIX, fX), antithrombin, protein C (PC) and free tissue factor pathway inhibitor (fTFPI) from 60 COPD patients (aged 64.2 ± 10.1 years; a mean forced expiratory volume in 1 second [FEV(1)], 55.6 ± 15.8% of predicted values) were compared with those for 43 controls matched for age, sex, weight and smoking. Patients receiving anticoagulation were excluded. Using each individual's plasma coagulation protein composition, tissue factor-initiated thrombin generation was assessed computationally.

RESULTS

COPD patients had higher fII (115 ± 16 vs 102 ± 10%, p < 0.0001), fV (114 ± 19 vs 102 ± 12%, p = 0.0002), fVII (111 ± 15 vs 102 ± 17%, p = 0.002), fVIII (170 ± 34 vs 115 ± 27%, p < 0.0001), and fIX (119 ± 21 vs 107 ± 17%, p = 0.003), and lower fTFPI (17.7 ± 3.2 vs 18.9 ± 3.2 ng/ml, p = 0.047) compared with controls, while fX, antithrombin, and PC were similar in both groups. Computational thrombin generation profiles showed that compared with controls, COPD patients had higher maximum thrombin levels (+28.3%, p < 0.0001), rates of thrombin generation (+46.1%, p < 0.0001) and total thrombin formation (+14.4%, p < 0.001), together with shorter initiation phase of thrombin generation (p < 0.0001) and the time to maximum thrombin levels (p < 0.0001). Thrombin generation profiles in COPD patients can be normalized via correction of fII, fVIII , fIX and TFPI. The severity of COPD and inflammatory markers were not associated with thrombin generation profiles.

CONCLUSIONS

Prothrombotic phenotype in COPD patients is largely driven by increased prothrombin, fVIII, fIX, and lower fTFPI.

Serum level of soluble intercellular adhesion molecule-1 correlates with pulmonary arterial pressure in children with congenital heart disease

BACKGROUND

Endothelial activation and vascular inflammation are thought to be the mechanisms of pulmonary hypertension. Increased expression of the intercellular adhesion molecule (ICAM-1) and raised serum level of its soluble form (sICAM-1) are found in various conditions associated with endothelial activation.

METHODS

Serum samples from 31 children (14 boys and 17 girls; age, 4.9 +/- 4.6 years) with congenital heart disease (CHD) collected at the time of cardiac catheterization were analyzed for sICAM-1 level. Uni- and multivariable stepwise linear regression analyses were performed for the following variables against the sICAM-1 level: age, hemoglobin, serum creatinine, systemic arterial pressure (SAP), pulmonary arterial pressure (PAP), pulmonary blood flow (Qp) and resistance (Rp), systemic blood flow (Qs) and resistance (Rs), Qp/Qs, Rp/Rs, and pulmonary and systemic oxygen saturation.

RESULTS

The sICAM-1 levels in children who had CHD with and without pulmonary hypertension were 411 +/- 110 and 344 +/- 81 ng/ml, respectively (p = 0.11). In the univariable models, age, serum creatinine, systolic PAP, mean PAP, diastolic PAP, Rp, and Rp/Rs were significantly correlated with sICAM-1 level. In the multiple stepwise regression model, only mean PAP remained as an independent predictor of sICAM-1 level (r = 0.55; p = 0.002).

CONCLUSION

Children with CHD and pulmonary hypertension had a trend toward elevated sICAM-1 compared with CHD children who had no pulmonary hypertension. A linear correlation was found between mean pulmonary arterial pressure and sICAM-1 level.

Changes in circulating thrombomodulin levels with exercise in patients with chronic obstructive pulmonary disease

BACKGROUND AND OBJECTIVES

The functional properties of endothelial cells in pulmonary microvessels are affected by elevations in the level of vascular endothelial growth factor (VEGF) in inflamed airways. An increase in the level of circulating thrombomodulin (TM), a molecular marker of endothelial cells, with exercise is associated with the VEGF level in asthmatic airways. This study investigated whether the airway VEGF level reflects changes in circulating TM levels with exercise in patients with COPD.

METHODS

VEGF levels in induced sputum were measured in 26 COPD patients (12 chronic bronchitis and 14 emphysema) and 11 control subjects. Incremental exercise testing was performed, and TM levels in arterial blood samples were measured pre-exercise and post-exercise at 0, 5 and 60 min.

RESULTS

VEGF levels were significantly lower in patients with emphysema (520 +/- 290 pg/mL) than in control subjects (1860 +/- 1220 pg/mL), and were significantly higher in patients with bronchitis (4110 +/- 1190 pg/mL). Pre-exercise TM levels were comparable among the three study groups. TM levels in control subjects and emphysema patients did not change after exercise. However, maximum TM levels after exercise were significantly increased in chronic bronchitis patients (P = 0.02). The increase in TM level with exercise closely correlated with the VEGF level in bronchitis patients (r = 0.90, P = 0.003).

CONCLUSIONS

In chronic bronchitis, but not in emphysema, patients exercise induced an increase in circulating TM levels. The potential causal relationship between circulating levels of TM and those of VEGF in the airways deserve further exploration.