Reliability of blood eosinophil count in steady-state bronchiectasis

RATIONALE

The baseline value of eosinophils in peripheral blood (BEC) has been associated with different degrees of severity, prognosis and response to treatment in patients with bronchiectasis. It is not known, however, if this basal value remains constant over time.

OBJECTIVES

The aim of this study was to assess whether the BEC remains stable in the long term in patients with bronchiectasis.

METHODS AND MEASUREMENTS

Patients from the RIBRON registry of bronchiectasis diagnosed by computed tomography with at least 2 BEC measurements one year apart were included in the study. Patients with asthma and those taking anti-eosinophilic drugs were excluded. Reliability was assessed using the intra-class correlation coefficient (ICC). A patient with a BEC of at least 300 cells/uL or less than 100 cells/uL was considered eosinophilic or eosinopenic, respectively. Group changes over time were also calculated.

MAIN RESULTS

Seven hundred and thirteen patients were finally included, with a mean age of 66.5 (13.2) years (65.8 % women). A total of 2701 BEC measurements were performed, with a median number of measurements per patient of 4 (IQR: 2-5) separated by a median of 12.1 (IQR: 10.5-14.3) months between two consecutive measurements. The ICC was good (>0.75) when calculated between two consecutive measurements (approximately one year apart) but had dropped significantly by the time of the next annual measurements. Similarly, the change from an eosinophilic or eosinopenic patient to a non-eosinophilic or non-eosinopenic patient, respectively, was less than 30 % during the first year with respect to the baseline value but was close to 50 % in later measurements.

CONCLUSIONS

Given the significant changes observed in the baseline value of the BEC over time, its monitoring is necessary in patients with bronchiectasis in order to more reliably assess its usefulness.

Effects of two types of training on pulmonary and cardiac responses to moderate exercise in patients with COPD

The effects of two 8-week programmes of exercise reconditioning on the time constants (tau) of the pulmonary gas exchange, ventilatory and heart rate responses to moderate intensity exercise in patients with chronic obstructive pulmonary disease (COPD) were studied. Thirty-five subjects (mean+/-SD 64+/-5 yrs; forced expiratory volume in one second (FEV1) 1.09+/-0.17 L; 41+/-6.2% predicted) were randomly assigned either to supervised (s) training on a treadmill, 4 days x week(-1) (group S; n=21) or self-monitored (SM) walking 3 or 4 km in 1 h 4 days x week(-l) (group SM; n=20). The different levels of supervision resulted in a different estimated intensity of training (35+/-10 W in the SM group and 70+/-22 W in the S group). The kinetics were evaluated with a constant-load exercise test on a cycle-ergometer at a work rate corresponding to 80% the highest oxygen consumption (V'O2) that can be achieved without blood lactic acidosis (V'O2,LAT) or 50% of V'O2,max, if maximum oxygen consumption V'O2,LAT was not found. Mean endurance time at a work rate equivalent to 70% of the pretraining V'O2,max increased by 493+/-281 s in the S group and 254+/-283 s in the SM group (p<0.001). Mean tauV'O2 decreased from 83+/-17 s to 67+/-11 s (p<0.0001) in the S group and from 84+/-12 to 79+/-16 (p=0.04) in the SM group. Mean tau for carbon dioxide output minute ventilation and heart rate were also speeded after training, again more markedly in the S group. In the S group there was a significant correlation between the decrease in tauV'O2 and the increase in endurance time (r=-0.56, SEM=0.21). It is concluded that training speeds the kinetic response of oxygen consumption, carbon dioxide production, minute ventilation and heart rate to moderate exercise and that the effect is greater after supervised, more intense training.

[Prediction of exercise capacity after lung resection in patients with chronic airflow limitation]

To assess the usefulness of a method for predicting postoperative peak oxygen uptake based on lost lung function after lung resection (VO2peak-PPO) and to establish the underlying physiological foundation for the relation between VO2peak-PPO and the measured postoperative value VO2peak-PO), we studied 29 patients (26 men) [age 60 (SD9)] with chronic airflow limitation [FEV1 = 66 (SD13)%] undergoing lobectomy or major pulmonary resection to treat lung cancer. The patients were assigned to groups according to whether postoperative exercise tolerance was considered to be limited by exhaustion of ventilatory reserve (LV) or not (NLV). Data to estimate postoperative pulmonary function was obtained one week before surgery: patients performed pulmonary function tests and exercise tests on a treadmill; dyspnea was also evaluated and perfusion scintigraphs were obtained. Pulmonary function, exercise tolerance and dyspnea were evaluated again approximately five months after surgery. The mean difference between VO2peak-PPO and VO2peak-PO was -0.034 (CI 0.293 to -0.348) l.min-1 and the between-group correlation coefficient was 0.76. The correlation between VO2peak-PPO and VO2peak-PO was 0.86 (SE 0.1) [0.89 (SE 0.13) for LV (n = 14) patients and 0.85 (SE 0.16) for NLV (n = 15) patients]. The correlations after adjusting for preoperative VO2peak-PPO were 0.73 (SE 0.2) and 0.35 (SE 0.27) for LV and NLV patients, respectively. We conclude that VO2peak-PPO provides a valid but only moderately precise estimate of VO2peak-PO. Only in LV patients is there a true relation between a decrease in VO2peak and loss of lung function.