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Pieter Zanen

Publications and source records attributed to Pieter Zanen.

14 recordsLinked to original sources
PubMed2007

Diffusing capacity for nitric oxide: reference values and dependence on alveolar volume.

Nitric oxide (NO) has a much stronger affinity for hemoglobin than carbon monoxide (CO); therefore, the DL(NO) (diffusing capacity for NO) is less influenced by changes in capillary blood volume than the DL(CO) (diffusing capacity for CO), and represents the true membrane diffusing capacity. We measured the combined single breath DL(NO)/DL(CO) in 124 healthy subjects, and generated reference equations for the DL(NO) and K(NO). In a subset of 21 subjects the measurements were performed on different inspiratory levels. The reference equation for DL(NO) in females is 53.47*H(height)0.077*A(age)-48.28(RSD5.22) and for males 59.84*H-0.25*A-44.20(RSD6.39). Reference equations for K(NO) in females is -2.03*H-0.025*A+11.52(RSD0.48) and for males -0.15*H-0.045*A+9.47(RSD0.65). The K(CO) (DL(CO)/V(A)) increases when V(A) (alveolar volume) decreases, probably due to an increase of blood volume per unit lung volume. The DL(NO) was much stronger related to the V(A), the K(NO) was almost independent of V(A). Because of the relative independence of the K(NO) on V(A), the K(NO) appears to be a much better index for the diffusion capacity per unit lung volume (transfer coefficient) than the K(CO).

Adult↗
PubMed2006

A comparison of lung function equipment with emphasis on interchangeability and methods.

The replacement of lung function equipment may not result in changing values: transitions should be seamless. We compared the equipment of two manufacturers (ZAN and Jaeger) to estimate the differences in spirometry, bodyplethysmography and diffusion capacity derived parameters elicited by equipment differences, and also compared calibration systems. From Jaeger (1) a Masterlab bodyplethysmograph, (2) a Pneumoscreen pneumotachograph, (3) a Masterscreen CS-FRC and (4) a Masterlab CompactTransfer (the latter two measure the diffusion capacity) were compared, and from ZAN a bodyplethysmograph system encompassing spirometry, flow-volume curve and diffusion capacity measurements. In vitro (a 2 litre calibration syringe at three flows, a fixed flow generator (0.5 l s(-1), 1.67 l s(-1) and 5 l s(-1)) and a wave form generator) studies and an in vivo cross-over study (N = 59) were used to compare the pneumotachographs. Other parameters were compared only via the in vivo study. The calibration syringe study showed no differences between the pneumotachographs: all volumes in all systems were within 3% of the reference. The fixed flow generator showed no flow differences either: again within 3% of the reference. The wave form generator showed PEF, MEF(75/50/25) differences up to 10-15% from the reference, but none in FEV(1) and FVC. The in vivo study found similar system differences in PEF, MEF(75/50/25): up to 29%. FEV(1), VC and FVC differed by small amounts (in all cases <3% between systems). R(0.5), TLC, V(A) and RV differed by small amounts between the systems (in all cases <3%), but T(L,CO) up to 9%. This study showed that between and within manufacturers, significant differences can exist between pneumotachographs and that using calibration syringes or fixed flow generators these frequently go unnoticed. These approaches insufficiently test the dynamic features of pneumotachographs. For other parameters, in vivo calibration is the only option and accuracy is only achieved with rather large samples, so more research is needed into suitable in vitro systems.

Equipment Design↗
PubMed2006

Relevant and redundant lung function parameters in discriminating asthma from COPD.

A relevant set of lung function parameters, derived from spirometry, flow-volume curves, diffusion capacity and bodyplethysmography, to discriminate asthma from COPD was established via logistic regression analysis. All new patients, referred to the outpatient clinic and later defined as asthma or COPD, underwent extensive lung function testing with reversibility testing. Logistic regression was used to calculate the probability to be a COPD or asthma patient. Selection of relevant parameters was done via 1] forward-, 2] backward-, 3] stepwise selection and 4] the best score method. All four methods were supplemented by bootstrapping to obtain a validated selection and estimation of the logistic regression parameters. The area under the ROC curve (mean+/-sd) for respectively the forward, backward, stepwise and best score selection method is 0.9348+/-0.0115, 0.9346+/-0.0115, 0.9348+/-0.0115 and 0.9296+/-0.0121. The TLCO, VA and the postdilator MEF50, VC and PEF were selected as the most relevant parameters in discriminating asthma from COPD: they appeared most often as relevant discriminators in 500 bootstrapped samples: TLco was present in all bootstrapped samples and VA, postdilator MEF50, VC and PEF in resp. 70.8%, 46.2%, 42.8% and 36.8%. Bodyplethysmography derived parameters turned out to be of limited value. Diffusion capacity testing and spirometry/flow-volume curve after administration of bronchodilators are the methods of choicewhen having to chose between asthma or COPD.

Adult↗
PubMed2006

Diffusing capacity for nitric oxide and carbon monoxide in patients with diffuse parenchymal lung disease and pulmonary arterial hypertension.

BACKGROUND: The passage of carbon monoxide (CO) through the alveolocapillary membrane and into the plasma and intraerythrocytic compartments determines the diffusing capacity of the lung for CO (DLCO) as defined by the Roughton and Forster equation. On the other hand, the single-breath diffusing capacity of the lung for nitric oxide (DLNO) is thought to represent the true membrane diffusing capacity because of its very high affinity for hemoglobin (Hb) and its independence from pulmonary capillary blood volume. Therefore, the DLNO/DLCO ratio can be used to differentiate between thickened alveolocapillary membranes (both DLNO and DLCO are decreased, and the DLNO/DLCO ratio is normal) and decreased perfusion of ventilated alveoli (the DLNO less decreased than the DLCO; therefore, the DLNO/DLCO ratio is high) in patients with pulmonary disease. STUDY DESIGN: We measured the combined values of DLCO and DLNO in 41 patients with diffuse parenchymal lung disease (DPLD), 26 patients with pulmonary arterial hypertension (PAH), and 71 healthy subjects. RESULTS: The DLCO (corrected to the standard Hb value) was lowered in the DPLD group (64% of predicted) and in the PAH group (64% of predicted), and was normal in the control group (105% of predicted). The DLNO/DLCO ratio in patients with PAH (4.98) was significantly higher than that in patients with DPLD (4.56) and in healthy subjects (4.36). CONCLUSION: The DLNO/DLCO ratio is significantly higher in patients with PAH than in healthy subjects, although this ratio cannot be applied as a screening test to discriminate between patients with DPLD and PAH as the overlap between these groups is too large.

Adult↗
PubMed2005

Discriminating asthma and COPD based on bronchodilator data: an improvement of the methods.

The degree of bronchodilation is usually expressed as a percentage of the predicted or baseline value. It has been shown that the relation between pre- and post-dilation lung function values is not adequately described by this approach: the sensitivity/specificity in separating asthmatics from cases of chronic obstructive pulmonary disease (COPD) could be improved. The alternative method we investigate is based on a logistic regression approach incorporating pre- and post-dilation lung function, age, sex and height. The discriminatory power of forced expiratory volume in one second (FEV1) increase as a percentage of the predicted or baseline FEV1 is compared to our approach using two databases containing bronchodilator data and diagnoses (asthma, chronic bronchitis or emphysema, the latter two grouped as (OPD). The increase as a percentage of the predicted or baseline approach and our alternative method show areas under the receiver operator curve (ROC) (males/females) of 0.552/0.629, 0.523/0.550 and 0.867/0.879 in one database. In the other database the same trend is present although less obvious: 0.628/0.730, 0.592/0.737 and 0.709/0.749. This increase in discriminatory power is obtained in the optimal use of all available information, especially age, which is not used in the increase of the predicted/baseline FEV1 rule.

Adult↗
PubMed2005

Validation of a new method to measure hydrogen peroxide in exhaled breath condensate.

Inflammatory processes in the lung can or will elicit oxidative stress. The degree of oxidative stress can be determined by measuring hydrogen peroxide (H(2)O(2)) concentration in exhaled breath condensate (EBC) but the methods to measure H(2)O(2) are all rather time consuming and only reliable and/or accurate in the hand of skilled technicians in a dedicated laboratory. We tested a new commercial device (Ecocheck), developed to offer a less time-consuming method to measure H(2)O(2). We validated this new method according the NCCLS EP10-A2 protocol. The validation shows that the imprecision in the low range is high (28.4%) and declines with higher concentrations of H(2)O(2) (up to 6.6%). The Ecocheck is "an easy to use" measuring device for routine measurements getting quick results without the need for skilled technicians to determine H(2)O(2) concentrations.

Adult↗
PubMed2005

Flow-volumes indices as means to discriminate between intra- and extrapulmonary restrictive disease.

Restrictive lung disease comes in two major categories: (1) intrapulmonary (= parenchymal) disease caused by fibrotic reactions or (2) extrapulmonary (= compression), like in heart failure. In the first category the conducting airways, tethered in stiffened structures, are less likely to be compressed during forceful expiration and expiratory flows hence are expected to remain high. This could serve as a cheap and easy diagnostic, avoiding more complicated measures. A database was build containing 624 patients suffering from either intra- and extrapulmonary disease. The flow-volume curve indices of restrictive patients (with a total lung capacity < -1.96 sd of reference) were compared and it was shown that in primary fibrotic disease and in leukaemia, indeed, the PEF and MEF(75/50/25) were significantly higher compared to the heart failure group (P < or = 0.001). The diabetes mellitus vs. heart failure differences were much less (P > 0.05). The area under the ROC to discriminate extra- from intrapulmonary disease was a low 0.607 and 0.606 for the PEF and MEF75, respectively. For the peakflow an optimal cut-off point was found at 65.8% of the reference value. The positive/negative predictive value of a peakflow < 65.8% to detect extrapulmonary disease was 30.1% and 82.2%, respectively.

Adult↗
PubMed2005

Prediction of early cerebral outcome by transcranial Doppler monitoring in carotid bifurcation angioplasty and stenting.

OBJECTIVE: The outcomes of carotid angioplasty and stenting (CAS) are, in addition to patient baseline characteristics, highly dependent on the safety of the endovascular procedure. During the successive stages of CAS, transcranial Doppler (TCD) monitoring of the middle cerebral artery was used to assess the association of cerebral embolism and hemodynamic changes with transient (amaurosis fugax and transient ischemic attack) and persistent (minor and major stroke) cerebral deficits, and death. METHODS: By use of a prospectively completed database of 550 patients, the association of various TCD emboli and velocity variables with periprocedural cerebral outcome 5) at postdilation after stent deployment (odds ratio [OR] 2.6, 95% confidence interval [CI], 1.3 to 5.1), particulate macroembolus (OR, 27.0; 95% CI, 4.5 to 157), and massive air embolism (OR, 51.4; 95% CI, 5.4 to 492), as well as angioplasty-induced asystole and prolonged hypotension with a >70% reduction of middle cerebral artery blood flow velocities (OR, 6.4; 95% CI, 2.3 to 17.8) were independently associated with cerebral deficits. The ROC area of this model was 0.72. Of the patient characteristics, only preprocedural cerebral ischemia (OR, 5.0; 95% CI, 2.4 to 10.4) was associated with outcome. Adding this patient characteristic to the model, the area under the ROC curve increased to 0.80. CONCLUSIONS: In CAS, in addition to such obviously adverse events as particulate macroembolism and massive air embolism, multiple microemboli (>5 showers) at postdilation after stent deployment and angioplasty-induced asystole and hypotension with a significant reduction of middle cerebral artery blood flow velocities are associated with periprocedural cerebral deficits. In combination with the presence of preprocedural cerebral symptoms, these four TCD monitoring variables reasonably differentiate between patients with and without adverse cerebral outcome. TCD monitoring provides insight into the pathogenesis of CAS related adverse cerebral events.

Aged↗
PubMed2005

Markers of inflammation and oxidative stress in exacerbated chronic obstructive pulmonary disease patients.

COPD is characterised by damage to small airways due to an inflammatory process as well as an imbalance between oxidants and antioxidants. Several cytokines and cell adhesion molecules enhancing a mainly neutrophilic inflammation have been associated with COPD. The aim of the study was to investigate whether inflammation or oxidative markers gave an indication of the course of COPD during an exacerbation. Fourteen patients with moderate to severe COPD admitted to the St. Antonius Hospital because of an exacerbation have been monitored during treatment with prednisolone 50 mg intravenously during 24 h at admission, reduced to 25 mg at day 3 and tapered off with oral prednisolone at day 7. On three separate occasions, day 1, 3 and 7, H2O2 in exhaled air, IL-8 and the soluble cell adhesion molecule sICAM and sE-selectin in serum were measured. We compared the patients at day 1 with healthy controls (in both non-smokers and smokers). Furthermore, we examined the changes from the study group in time during therapy. At admission all the markers were raised in comparison with the control groups. During treatment H2O2 concentrations in breath condensate declined significantly (P<0.001) as well as IL-8 and sICAM in serum (P=0.002, respectively, P<0.001). There was no significant change in sE-selectin (P=0.132). No significant improvement has been found in spirometry. These data suggest that the markers H2O2 in exhaled air, IL-8 and sICAM in serum are suitable markers in monitoring exacerbated COPD.

Aged↗
PubMed2005

Analysis of KL-6 and SP-D as disease markers in bird fancier's lung.

BACKGROUND AND AIM: KL-6 and SP-D are potential serum markers in interstitial lung diseases. Their discriminative value, and ability to reflect pulmonary disease activity and prognosis in bird fancier's lung were analyzed. METHODS: We studied 49 patients, 38 unexposed and 9 exposed controls. Serum KL-6 and SP-D concentrations were measured at presentation and a second sample, taken after antigen avoidance, was available in 17 patients. Pulmonary function tests were analyzed at presentation and 2-year follow-up. RESULTS: KL-6 and SP-D were significantly elevated in patients compared to controls (p < 0.0001). ROC curve analysis revealed that both are equally useful in discriminating patients from controls. Analysis of their value as activity markers showed that both correlated with pulmonary function impairment; however, KL-6 correlated best with diffusing capacity. Evaluation of their predictive value showed that higher levels at onset were associated with improvement of diffusing capacity during follow-up. Further, it was noted that KL-6 and SP-D levels decreased after more than one month of allergen avoidance. CONCLUSIONS: KL-6 and SP-D appear useful serum markers in bird fancier's lung. Since higher levels are associated with more severe lung function impairment at presentation, and better recovery over time, we postulate that in this disease they are especially markers of disease activity.

Antigens↗
PubMed2004

Analyzing bronchodilation with emphasis on disease type, age and sex.

In the literature, different statistical methods to evaluate bronchodilator studies are used. These approaches are all based on the absence of residual heterogeneity and on baseline independency of the parameter under analysis. A database containing the lung function values of newly referred patients was used to assess these assumptions as function of the underlying diagnosis (asthma, bronchitis and emphysema) and to chart the characteristics of analysis of covariance, which (partly) deals with these drawbacks. Bronchodilator data of 709 asthmatics, 522 bronchitic and 126 emphysema patients were used. It was shown that, in asthma, for almost all lung function parameters, bronchodilation was indeed dependent on baseline values, which was less strong in bronchitis and even weaker in emphysema. A negative effect of age on bronchodilation was found, which is strong in asthma and almost absent in emphysema, rendering the use of bronchodilation as a diagnostic tool less useful. The conclusion is that analysis of covariance is a good way to evaluate bronchodilation studies in obstructive lung disease, particularly in asthma. For bronchitic or emphysema patients, difference-based approaches may suffice. The assumptions underlying the other methods were not met.

Adult↗
PubMed2002

Selecting the best method to evaluate bronchodilation when analysing bronchodilator studies.

Changes in lung function (that is, FEV(1)) are commonly expressed as a percentage of the predicted value. The question is whether this parameter is best suited for statistical analysis. A total of 2199 bronchodilation tests were selected and pre- and post-dilator FEV(1), age, height and sex extracted. Predicted FEV(1) values, the difference between pre- and post-dilator FEV(1) and the change as percentage of predicted or baseline FEV(1) were calculated. The latter parameters were subjected to analysis of variance and pre- and post-dilator FEV(1) to analysis of covariance. The statistical power of these four approaches and the residual structure were used to select the best approach. Analysis of variance of the change as percentage of predicted and covariance analysis of pre- and post-dilator FEV(1) offers the best performance. The residuals of the analysis of variance showed a funnel shaped structure. The latter causes residual heterogeneity, resulting in a loss of power and deviations between the actual and nominal alpha-level. This is not taken into account when calculating sample sizes using the standard equations, which implicitly assume lack of these problems. Analysis of covariance does not suffer from these problems. The best way to evaluate bronchodilation in trials is to use analysis of covariance.

Age Factors↗
PubMed2002

Quantification of right-to-left shunt with (99m)Tc-labelled albumin macroaggregates and 100% oxygen in patients with hereditary haemorrhagic telangiectasia.

Pulmonary arteriovenous malformations (PAVMs) are often associated with hereditary haemorrhagic telangiectasia (HHT). The quantification of right-to-left shunts in patients with PAVMs is important in diagnosis and follow up. Traditionally, this shunt is measured by the 100% oxygen method, in which the value for the arteriovenous difference in oxygen content, Cao(2)-CVO(2) (where Cao(2) is the oxygen content of arterial blood and CVO(2) is the oxygen content of mixed venous blood) is estimated. Alternative methods consist of measurement of the systemic or renal uptake of (99m)Tc-labelled macroaggregates of albumin (MAA), which are trapped in pulmonary capillaries, but pass through PAVMs. We first measured Cao(2)-CVO(2) in 12 HHT patients before and after embolization of PAVMs. We obtained a mean value of 4.4 ml/100 ml, instead of the usual 5 ml/100 ml. Subsequently, we measured right-to-left shunt in 21 HHT patients using the 100% oxygen method and with two different methods involving (99m)Tc. We used the kidney-lung method (K/L method), in which it is assumed that the right kidney receives 10% of the cardiac output, and we also used a method with two tracers (HSA/MAA method): (1) (99m)Tc-labelled human serum albumin (HSA) (which passes through pulmonary capillaries) to measure the fraction of the cardiac output perfusing the kidneys, and (2) MAA to measure the shunt fraction. In 35 shunt measurements we evaluated this new technique and the K/L method, by comparing the results with those from the 100% oxygen method. There was poor agreement between the 100% oxygen method and the K/L method, with 95% limits of agreement for the shunt fraction of -15.2% to +15.2%. There was moderate agreement between the 100% oxygen method and the HSA/MAA method, with limits of agreement of -8.3% to +7.7%. We conclude that the different methods cannot replace each other, because the limits of agreement are too wide for clinical use.

Adult↗