Lung clearance index: a new measure of ventilation inhomogeneity in childhood respiratory diseases

: Conventional spirometry has long been considered the primary test for assessing respiratory function deficits in children and adults. However, the need to perform forced breathing maneuvers can make it challenging to perform these examinations in an uncooperative child. For these reasons, techniques such as gas dilutions and the multiple-breath-washout (MBW) method have been implemented because they allow for early assessment of damage to the small airways. These methods permit the determination of the possible presence of ventilatory inhomogeneity in the lungs by analyzing the clearance of an inert gas used as a tracer. The equipment consists of a mass spectrometer combined with a flow meter. The Lung Clearance Index (LCI) is most often used to evaluate ventilatory inhomogeneity. This narrative review aimed to review the literature on technical and practical aspects of the MBW test and evaluate the clinical implications of the LCI in pediatric respiratory disease.

Bioguided Isolation of Alkaloids and Pharmacological Effects of the Total Alkaloid Fraction from Aspidosperma pyrifolium Mart. (Apocynaceae)

Aspidosperma pyrifolium is used in traditional medicine to treat inflammatory disorders. The aim of the study was to perform phytochemical characterization and evaluate the anti-inflammatory, anti-nociceptive and acute toxicity effects of the total alkaloid fraction (TAF-Ap) from stem barks. Two monoterpenic indole alkaloids were isolated by high performance liquid chromatography coupled with mass spectrometry (HPLC-MS) and the structural elucidation was performed using 1D and 2D NMR analysis. As for toxicity, no animals died at 50 mg kg−1 and this concentration presented mild sedation and forced breathing within the first 24 h. The lethal dose capable of killing 50% of the animals (LD50) was estimated to be 160 mg kg−1. In the pharmacological tests, the models used were 1% carrageenan-induced paw edema and peritonitis, 1% formalin-induced nociception and 1% acetic acid-induced abdominal writhing in Swiss mice. The study made it possible to isolate 15-methoxyaspidospermine and 15-methoxypyrifolidine, corroborating the results of pharmacological assays, which showed anti-inflammatory and analgesic potential, especially at 30 mg kg−1 (p < 0.001). Thus, the species was shown to be a promising source of active substances, with special attention paid to its toxicological potential.

FEATURES OF VENTILATION DISORDERS IN PATIENTS WITH HYPERTENSION

The signs of hyperventilation syndrome are detected among hypertensive patients, but are notnoticed by doctors that in some way can complicate the progression of the hypertension. It was established during the research that for the hypertensive syndrome and its extent of reveal verification, besides standardized Nijmegen questionnairespirometry or diaphragm amplitude can be used. It was established, that among group of hypertensive patients (n=43) with the signs of hyperventilation syndrome, the decrease of lung ventilation figures in accordance to proper magnitude was revealed. Specifically, such figures as vital capacity, forced expiratory volume in 1 sec, inspiratory and expiratory reserve volume, peak expiratory flowwere accurately lower. The reveled changes increased after conducting of the hyperventilation probe among all patients of the main group. At the same moment only among 28,57 % of patients from control group (n=14), without signs of hyperventilation syndrome, according to the survey, the violation of lung ventilation from slight (21,43 %) to moderate (7,14 %) was revealed under the hyperventilation probe. Besides that, among patients from the main group the limitation of diaphragm amplitude was noticed in comparison to results gained in the control group which became stronger under the forced breathing. The revealed changes among hypertensive patients require on time diagnostic and correction.

Impact of artificial airway resistances on regional ventilation distribution during airway closure

Electrical impedance tomography (EIT), a noninvasive and radiation-free imaging technique can be used in pulmonary function monitoring for determining regional ventilation distribution within the lung. Gold standard in pulmonary function monitoring is spirometry/body plethysmography, a method using forced breathing maneuvers to obtain global lung function parameters. However, this method is heavily dependent on the cooperation of the patients. Within this observational study, a method under normal breathing was tested with 5 healthy volunteers, which provides regional information about ventilation distribution. The occlusion method Rocc, a method for determining airway resistance, was used to create a short-term airway closure. Regional ventilation during the airway closure was examined with EIT. Simultaneously four different artificial airway resistances were used to simulate airway obstructions. Results show that EIT in combination with the ROcc method is suitable for the detection of regional differences in ventilation during airway closure for all four artificial airway resistances. Although the sum of relative impedances at the end of the shutter maneuver are smaller (nearly -0.100 AU) for the airway resistances Ø 12.5 mm, Ø 10.5 mm and Ø 9.5 mm than for the smallest one with Ø 30.0 mm (~ -0.070 AU), the changes in impedance from the start to the end of the shutter maneuver differs only slightly between the four artificial airway resistances. All impedance changes are in the range of 0.100 to 0.130 AU. The combination of EIT and the ROcc method provides not only global parameters such as airway resistance under normal breathing conditions, but also results of regional ventilation, which could enable the identification of areas affected by airway obstructions. However, the obtained results indicate that EIT might be a useful tool in the diagnosis and follow-up of obstructive lung diseases.

Assessing paediatric exercise-induced bronchoconstriction using electromyography

BackgroundAsthma is one of the most common chronic diseases in childhood, occurring in up to 10% of all children. Exercise-induced bronchoconstriction (EIB) is indicative of uncontrolled asthma and can be assessed using an exercise challenge test (ECT). However, this test requires children to undergo demanding repetitive forced breathing manoeuvres. We aimed to study the electrical activity of the diaphragm using surface electromyography (EMG) as an alternative measure to assess EIB.MethodsForty-two children suspected of EIB performed an ECT wearing a portable EMG amplifier. EIB was defined as a fall in FEV1 of more than 13%. Children performed spirometry before exercise, and at 1, 3 and 6 min after exercise until the nadir FEV1 was attained and after the use of a bronchodilator. EMG measurements were obtained between spirometry measurements.ResultsTwenty out of 42 children were diagnosed with EIB. EMG peak amplitudes measured at the diaphragm increased significantly more in children with EIB; 4.85 μV (1.82–7.84), compared to children without EIB; 0.20 μV (−0.10–0.54), (p<0.001) at the lowest FEV1 post-exercise. Furthermore, the increase in EMG peak amplitude could accurately distinguish between EIB and non-EIB using a cut-off of 1.15 μV (sensitivity 95%, specificity 91%).ConclusionEMG measurements of the diaphragm are strongly related to the FEV1 and can accurately identify EIB. EMG measurements are a less invasive, effort-independent measure to assess EIB and could be an alternative when spirometry is not feasible.

Incidence and predictive factors of diaphragmatic dysfunction in acute stroke.

Background: The most characteristic clinical signs of stroke are motor and/or sensory involvement of one hemibody. Respiratory involvement has also been described, which could be related to diaphragmatic dysfunction contralateral to the brain injury. Our objective is to establish the incidence of diaphragmatic dysfunction in ischaemic stroke and analyse the relationship between this and the main prognostic markers. Methods : Patients with supratentorial ischaemic stroke were selected in the first 48 hours of admission for 6 months. Ultrasonography of the diaphragm was performed on each hemithorax to obtain the thickening fraction applying the formula [(inspiratory thickness - expiratory thickness)/expiratory thickness]. Forced breathing was then requested to them and the examination was performed again. Diaphragmatic dysfunction was considered as a thickening fraction lower than 20%. The statistical relationship with the vascular territory involved, the NIHSS scale, the hemiparesis degree and the success of reperfusion techniques were examined. Results : An incidence of diaphragmatic dysfunction of 51.7% was observed on the contralateral side and of 1.7% on the ipsilateral side. A reduction of up to 11.7% was seen in the incidence of dysfunction on the contralateral side upon breathing forcedly. All patients with NIHSS above 6 had diaphragmatic dysfunction on the contralateral side (p < 0.001). They also had lower degrees of muscle strength (p < 0.001). Conclusions : There is a high incidence of diaphragmatic dysfunction in patients with supratentorial ischaemic stroke. An estimation of the diaphragmatic function can be obtained using the thickening fraction.

Cyanogenic poisoning by spontaneous ingestion of star grass (Cynodon nlemfuensis var. nlemfuensis cv. ‘Florico’) in cattle

ABSTRACT: This study reports the epidemiological data and the clinical-pathological condition of five outbreaks of cyanogenic poisoning in cattle spontaneously ingesting star grass (Cynodon nlemfuensis Vanderyst var. nlemfuensis cv. ‘Florico’). In all outbreaks, the areas where the plant was previously fertilized with high concentrations of nitrogen and the properties adopted the silvipastoral system. The first clinical signs appeared between 10 and 15 minutes after the first introduction of cattle and were characterized by muscular tremors, dyspnea, moderate tympanism, staggering gait, forced breathing with open mouth, sternal recumbency followed by death after 15 to 30 minutes and/or recovery in a few hours after the signs started. In total, 43 cows have become ill and 18 died. Two necropsies were performed and no significant changes were found except for the presence of the plant near the esophageal sphincter region. No histological lesions were seen through microscopy. Green leaves of the star grass were collected from all properties where the outbreaks occurred and the test of the picro-sodium paper was performed, revealing red-brick coloration in 20 minutes after maceration of the leaves.