Assessment of Extensive Airway Obstruction Using Point-by-Point Lateral Pressure Measurements during Bronchoscopy.

BACKGROUND: The positioning of the stent at the flow-limiting segment is crucial for patients with extensive airway obstruction to relieve dyspnea. However, CT and flow-volume curves cannot detect the area of maximal obstruction. OBJECTIVES: The aim of this study is to physiologically evaluate extensive airway obstruction during interventional bronchoscopy. METHODS: We prospectively measured point-by-point lateral airway pressure (Plat) at multiple points from the lower lobe bronchus to the upper trachea using a double-lumen catheter in 5 patients. The site of maximal obstruction was evaluated continuously to measure point-by-point Plat at multiple points when the airway catheter was withdrawn from the lower lobe bronchus to the upper trachea. RESULTS: Remarkable pressure differences occurred at the site of maximal obstruction assessed by point-by-point Plat measurements. After initial stenting in 1 case, migration of the maximal obstruction to a nonstented segment of the weakened airway was seen with extensive stenosis from the trachea to the bronchi. In the second case, in addition to radiological analysis, point-by-point Plat measurements could identify the location of the maximal obstruction which contributed to dyspnea. CONCLUSIONS: Point-by-point Plat measurement could be used to detect the site of maximal obstruction physiologically. Furthermore, Plat measurement could assess the need for additional procedures in real time in patients with extensive airway obstruction.

Assessment of regional lung ventilation by electrical impedance tomography in a patient with unilateral bronchial stenosis and a history of tuberculosis / Avaliacao da ventilacao pulmonar regional por tomografia de impedancia eletrica em paciente com estenose bronquica unilateral pos-tuberculose

Bronchial stenosis can impair regional lung ventilation by causing abnormal, asymmetric airflow limitation. Electrical impedance tomography (EIT) is an imaging technique that allows the assessment of regional lung ventilation and therefore complements the functional assessment of the lungs. We report the case of a patient with left unilateral bronchial stenosis and a history of tuberculosis, in whom regional lung ventilation was assessed by EIT. The EIT results were compared with those obtained by ventilation/perfusion radionuclide imaging. The patient was using nasal continuous positive airway pressure (CPAP) for the treatment of obstructive sleep apnea syndrome. Therefore, we studied the effects of postural changes and of the use of nasal CPAP. The EIT revealed heterogeneous distribution of regional lung ventilation, the ventilation being higher in the right lung, and this distribution was influenced by postural changes and CPAP use. The EIT assessment of regional lung ventilation produced results similar to those obtained with the radionuclide imaging technique and had the advantage of providing a dynamic evaluation without radiation exposure.

A estenose brônquica pode comprometer a ventilação pulmonar regional devido a limitações anormais e assimétricas ao fluxo aéreo. A tomografia de impedância elétrica (TIE) é uma técnica que possibilita a avaliação da ventilação pulmonar regional por imagem e, portanto, pode complementar a avaliação funcional dos pulmões. Relatamos o caso de uma paciente com estenose brônquica unilateral à esquerda, pós-tuberculose, em que se avaliou a ventilação pulmonar regional através da TIE, relacionando-a com a cintilografia de ventilação/perfusão. Foram estudados os efeitos das mudanças posturais e da aplicação de continuous positive airway pressure (CPAP, pressão positiva contínua nas vias aéreas) nasal, uma vez que a paciente usava esse tratamento para síndrome da apneia obstrutiva do sono. A TIE demonstrou distribuição heterogênea da ventilação pulmonar regional com maior ventilação no pulmão direito, sendo essa distribuição influenciada pelas mudanças de decúbitos e pela aplicação de CPAP. A análise da ventilação pulmonar regional pela TIE se mostrou similar aos achados da cintilografia pulmonar de ventilação com a vantagem de possibilitar uma avaliação dinâmica e sem exposição à radiação.

Assessment of regional lung ventilation by electrical impedance tomography in a patient with unilateral bronchial stenosis and a history of tuberculosis.

Bronchial stenosis can impair regional lung ventilation by causing abnormal, asymmetric airflow limitation. Electrical impedance tomography (EIT) is an imaging technique that allows the assessment of regional lung ventilation and therefore complements the functional assessment of the lungs. We report the case of a patient with left unilateral bronchial stenosis and a history of tuberculosis, in whom regional lung ventilation was assessed by EIT. The EIT results were compared with those obtained by ventilation/perfusion radionuclide imaging. The patient was using nasal continuous positive airway pressure (CPAP) for the treatment of obstructive sleep apnea syndrome. Therefore, we studied the effects of postural changes and of the use of nasal CPAP. The EIT revealed heterogeneous distribution of regional lung ventilation, the ventilation being higher in the right lung, and this distribution was influenced by postural changes and CPAP use. The EIT assessment of regional lung ventilation produced results similar to those obtained with the radionuclide imaging technique and had the advantage of providing a dynamic evaluation without radiation exposure.

Assessment and prevention of exercise-induced bronchoconstriction.

The assessment of exercise-induced bronchoconstriction (EIB) in athletes requires the measurement of forced expiratory volume in 1 s (FEV(1)) before and after vigorous exercise or a surrogate of exercise such as eucapnic voluntary hyperpnoea (EVH) of dry air or mannitol dry powder. Exercise testing in a laboratory has a low sensitivity to identify EIB, and exercise testing in the field can be a challenge in itself particularly in cold weather athletes. The EVH test requires the subject to ventilate dry air containing ∼5% CO(2) for 6 min through a low-resistance circuit at a rate higher than that usually achieved on maximum exercise. A ≥10% reduction in FEV(1) is a positive response to exercise and EVH and, when sustained, is usually associated with release of inflammatory mediators of broncho constriction. Another surrogate, mannitol dry powder, given by inhalation in progressively increasing doses, is used to mimic the dehydrating stimulus of exercise hyperpnoea. A positive mannitol test is a 15% fall in FEV(1) at ≤635 mg and reveals potential for EIB. Mannitol has a high specificity for identifying a clinical diagnosis of asthma. Once a diagnosis of EIB is established, the athlete needs to know how to avoid EIB. Being treated daily with an inhaled corticosteroid to reduce airway inflammation, inhaling a ß(2) agonist or a cromone immediately before exercise, or taking a leukotriene antagonist several hours before exercise, all inhibit or prevent EIB. Other strategies include warming up prior to exercise and reducing respiratory water and heat loss by using face masks or nasal breathing.

Collateral ventilation in a canine model with bronchial obstruction: assessment with xenon-enhanced dual-energy CT.

PURPOSE: To determine the feasibility of the use of xenon-enhanced dynamic dual-energy computed tomography (CT) for visualization and quantitative assessment of collateral ventilation in a canine model with bronchial obstruction. MATERIALS AND METHODS: This study was approved by the institutional animal care and use committee. One segmental bronchus was occluded in nine dogs (weight range, 20-25 kg). Dynamic dual-energy CT scanning was performed by using dual-source CT during the wash-in-washout study of xenon inhalation via mechanical ventilation. Imaging parameters were 14 x 1.2-mm collimation, 40 mAs (effective) at 140 kV and 170 mAs (effective) at 80 kV, pitch of 0.45, and 0.33-second rotation time. By using dual-energy software, CT images and xenon maps were reconstructed. CT attenuation values were measured in the airways proximal to obstruction (AW(PROX)) and airways distal to obstruction (AW(DIST)) and at the parenchyma with patent airways (P(PATE)) and parenchyma with obstructed airways (P(OBST)). CT attenuation values on dynamic xenon maps were plotted with exponential function; ventilation parameters, including velocity of ventilation (K value), magnitude of ventilation (A value), and time of arrival (TOA), were calculated on the basis of the Kety model. RESULTS: In all animals, delayed and weaker xenon enhancement was identified at the airway and parenchyma distal to obstruction. For the A value, in the wash-in study, the differences between AW(PROX) and AW(DIST) and between P(PATE) and P(OBST) were significant (71.80 and 57.64, P = .05; 51.86 and 37.52 HU, P = .02). The K value of P(OBST) was lower than that of P(PATE) in the wash-in study (0.006 and 0 .010, P = .06). Mean and standard deviation for TOA were observed in the following increasing order: AW(PROX) ([3.50 +/- 7.70] x 10(-6) sec), P(PATE) (4.58 +/- 2.83), AW(DIST) (9.20 +/- 6.87), and P(OBST) (21.00 +/- 13.44). CONCLUSION: Collateral ventilation in a canine model with bronchial obstruction can be quantitatively assessed by using xenon-enhanced dynamic dual-energy CT.

[The sinobronchial syndrome. Assessment of the influence of the upper on the lower airway diseases]. / Das sinubronchiale Syndrom.

Epidemiological and clinical data are discussed dealing with a possible influence of inflammatory changes of the nasal and especially the paranasal tissue on lower airway disease like asthma, the so-called "sinobronchial syndrome". Even though there is clear evidence of an association of the upper with the lower airway diseases, a causal relationship and a possible work of action are still up for discussion. The literature has been reviewed, and different theories are discussed. Generally speaking, a branch of differently accentuated mechanisms seems to play a role.

Tracheomalacia and bronchomalacia in children: pathophysiology, assessment, treatment and anaesthesia management.

Tracheomalacia and bronchomalacia are becoming increasingly well recognized. Although pathologically benign conditions, they are responsible for considerable morbidity, occasional mortality and significant difficulties in the operating theatre and intensive care unit. We performed an extensive literature search to identify causal associations, methods of clinical and investigative assessment, treatment modalities and anaesthetic experience with these conditions.

Quantitative assessment of intrathoracic airway collapse in infants and children with tracheobronchomalacia.

Tracheobronchomalacia (TBM) is increasingly recognized in infants, children, and adults with acquired chronic lung diseases as the use of flexible bronchoscopy has become widely established in spontaneously breathing patients. However, the lack of a reliable method to quantify the severity of the airway collapse has made serial studies, evaluation of therapies, and comparisons between patients difficult. The purpose of this study was to describe a method of quantifying airway collapse in TBM. The degree of airway collapse was quantitated by measuring the ratio of the smallest to the largest airway area during a respiratory cycle. The videotape of flexible bronchoscopy was run through a video monitor and frozen at the appropriate times. The airway circumference was then traced onto plastic overlays and the area measured. The videotapes of seven infants and children with TBM and eight with normal airways were reviewed by investigators who did not know the diagnosis. Intra-observer variability was 2.2%, and inter-observer variability was 1.4%. The mean smallest/largest airway ratio was 0.34 + or - 0.14 (SD) in the subjects with known TBM, compared with a ratio of 0.82 + or - 0.08 (SD) in children with a normal airway (P< 0.0001). The range in the children with TBM was 0.22-0.61, whereas for the control children it was 0.73-0.93. In this series, there was no overlap in the ratios between affected and unaffected patients. In addition to the manual method of calculating airway area ratios, a computer-assisted method is described that could be adapted to real-time use. This way of analyzing the degree of airway collapse could be used to assess patients with TBM quantitatively and reproducibly.

Assessment of tidal breathing patterns for monitoring of bronchial obstruction in infants.

Two parameters of tidal breathing, the ratio of time to reach peak tidal expiratory flow to the total expiratory time (Tme/TE) and the ratio of volume exhaled at peak tidal expiratory flow to the total exhaled volume (dV/VT) were used to assess lung function in 21 sedated infants (aged 6-14 mo) with different degrees of airway obstruction. These parameters were compared with airway resistance as percentage predicted (Raw%) and maximum expiratory flow at functional residual capacity corrected for lung volume (VmaxFRC/TGV). VmaxFRC/TGV values correlated significantly with Tme/TE (r = 0.630, p = 0.002) as well as with dV/VT (r = 0.728, p = 0.001). Raw% values showed only a weak correlation with dV/VT (r = -0.435, p = 0.048). We conclude that Tme/Te and dV/VT are both able to detect airway obstruction in infants and that these parameters correlate much better with the forced expiratory flow values obtained by the rapid thoracic compression method than with airway resistance, determined by body plethysmography.

Plethysmographic measurements in the clinical assessment of infants with bronchopulmonary disease.

Whole-body plethysmography makes it possible, to measure, during the same test sequence, the end-expiratory resting level (thoracic gas volume (TGV)), and, hence, an estimate of lung volume, and its close inter-relationship to airway function (airway resistance (Raw), or its reciprocal value airway conductance (Gaw). An overview is given of the physiological background and some equipment required for this technique. Furthermore, the attractive usefulness of whole-body plethysmography in clinical routine is discussed. Based on plethysmographic data obtained in 118 infant survivors of respiratory distress syndrome (RDS), in wheezy infants and infants with cystic fibrosis (CF), the important inter-relationship between changes in end-expiratory resting level (TGV) and the deficit in airway mechanics (Gaw) is shown, and special emphasis is given to the absolute need to obtain these measurements simultaneously. It can be shown that this recommendation is of even greater clinical importance in view of the fact that the younger the child the more frequent and severe the pulmonary hyperinflation present. Finally, this inter-relationship has to be borne in mind when reversibility of functional abnormalities on adrenoceptor agonists is assessed by lung function measurements.

[The assessment of pulmonary arterial pressure by pulsed Doppler in patients with obstructive pneumopathy]. / Valutazione della pressione arteriosa polmonare mediante Doppler pulsato nei pazienti affetti da pneumopatia ostruttiva.

The severity of pulmonary arterial hypertension can be assessed by duplex-Doppler echocardiography, a subxiphoid approach and a general-purpose duplex device. Normally, the peak Doppler flow velocity occurs in midsystole and the flow profile is parabolic (bullet-like). In pulmonary arterial hypertension, changes in vascular compliance cause maximal acceleration of blood in early systole, with shortening of pulmonary acceleration time (AcT, or time to peak velocity). In the more severe cases, a midsystolic notching is visible, related to rapid deceleration of blood flow, followed by a brief secondary increase in velocity in the late systole. We studied 19 adult patients with chronic obstructive pulmonary disease with duplex-Doppler examination, with a subxiphoid approach and right heart catheterization. The study was diagnostic in all cases with Doppler recordings of good quality. An relationship was found between AcT and pulmonary mean or systolic arterial pressure at rest. An evident accurate prediction of pulmonary arterial pressure in emphysematous patients is possible by means of pulsed Doppler, also in case of low-level hypertension. We believe this method to be a simple and reliable adjunct to the non-invasive work-up of emphysematous patients and to represent a good alternative to the classical parasternal approach, which is often not feasible in these patients.

[Correlation of parameters of the flow-volume curve for the assessment of bronchial hyperreactivity]. / Korrelation von Parametern der Flussvolumenkurve zum Ausmass der bronchialen Hyperreagibilität.

The association of maximal expiratory flow-volume curve and the response of nonspecific bronchial responsiveness was studied in 265 normal and asthmatic subjects. Bronchial hyperresponsiveness to acetylcholine was found in 143 subjects. These hyperreactive persons had already significantly reduced maximal expiratory flow rate at 75%, 50% and 25% vital capacity before the test started. Besides, we found a significant correlation between the provocative dose and the flow-volume parameters, although resistance was in the normal range. We concluded that the flow rates at middle and low lung volumes may be an important determinant of bronchial sensitivity to acetylcholine.

[Assessment of working capacity in a group of subjects affected with obstructive respiratory disease (author's transl)]. / Valutazione della capacita lavoritava in un gruppo di soggeti broncoostruttivi

Ventilatory function was studied by the authors in 43 subjects affected with obstructive respiratory disease. The research was performed both at rest and during two exercise tests -- 60 and 100 watts, respectively. The subjects were divided into three groups on the basis of tidal volume (at 30 1 ventilation) / vital capacity ratio. It was found that during muscular effort subjects with major impairment of spirometric indexes hypoventilated, whereas the opposite occurred in patients with lesser impairment. Moreover, subjects hyperventilating during muscular work were found to have brandypnea, whereas the opposite occurred in hyperventilating patients. It is suggested that progressing and worsening of obstructive emphysema lead to a relative hypoventilation during muscular work, which is due to an "inability" to increase the frequency of breathing.