Evaluation of spirometry gated CT scan to measure lung volumes in emphysema patients

IntroductionIn emphysema patients, being evaluated for bronchoscopic lung volume reduction (BLVR), accurate measurement of lung volumes is important. Total Lung Capacity (TLC) and Residual Volume (RV) are commonly measured by body-plethysmography, but can also be derived from chest computed tomography (CT). Spirometry-gated CT scanning potentially improves the agreement of CT and body-plethysmography.ObjectiveTo compare lung volumes derived from spirometry-gated CT and “breath-hold-coached” CT to the reference standard: body-plethysmography.MethodsIn this single centre retrospective cohort study, emphysema patients, evaluated for BLVR, underwent body-plethysmography, inspiration (TLC) and expiration (RV) CT-scan with spirometer guidance (“gated group”) or with breath-hold-coaching (“non-gated group”). Quantitative analysis was used to calculate lung volumes from the CT.ResultsWe included 200 patients (age 62±8 years, FEV1 29.2±8.7%, TLC 7.50±1.46 L, RV 4.54±1.07 L). The mean CT-derived TLC was 280(±340)ml lower compared to body-plethysmography in the gated group (n=100), and 590(±430)ml lower for the non-gated group (n=100) (both p<0.001). The mean CT-derived RV was 300(±470)ml higher in the gated group and 700(±720)ml higher in the non-gated group (both p<0.001). Pearson correlation factors were 0.947 for TLC gated, 0.917 for TLC non-gated, 0.823 for RV gated, 0.693 for RV non-gated, 0.539 for %RV/TLC gated and 0.204 for %RV/TLC non-gated. The differences between the gated and non-gated CT results for TLC and RV were significant for all measurements (p<0.001).ConclusionIn severe COPD patients with emphysema, CT-derived lung volumes are strongly correlated to body-plethysmography lung volumes, and especially for RV, more accurate when using spirometry-gating.

Changes in lung inflation in asthma in patients with osmotic airway hyperresponsiveness

The scientific literature does not provide enough information on whether bronchial hyperresponsiveness to hypoosmotic stimulus in patients with asthma can lead to more pronounced disturbances of regional lung ventilation.Aim. to characterize lung inflation in asthma patients with osmotic airway hyperresponsiveness.Methods. The lung inflation was studied by body plethysmography, as well as by three-dimensional volumetry, planimetry, and multispiral CT densitometry in 24 patients (group 1) with persistent mild asthma and osmotic airway hyperresponsiveness, identified by the bronchoprovocation test with inhalation of distilled water (IDW) (the average ДРБУ1 was —21.1 ± 3.2%). The comparison group (group 2) consisted of 49 patients with no response to IDW (the average ДББУ1 was —3.7 ± 0.5%; p = 0.00001).Results. Group 1 had lower lung function (FEVj was 83.6 ± 4.5%; FEF50 was 58.1 ± 5.8%) at baseline in comparison with the group 2 (96.7 ± 2.2%, p = 0.0042 and 75.5 ± 2.2%, p = 0.016, respectively) and higher indices of lung inflation at body plethysmography (RV was 153.2 ± 12.5 and 127.5 ± 4.0%, respectively; p = 0,027; RV/TLC was 128.8 ± 5.5 and 109.9 ± 2.8%, respectively; p = 0.015). According to three-dimensional volumetry, the indicators of expiratory lung inflation (526.0 ± 117.8 vox) and average residual inflation of both lungs (13.1 ± 2.6 vox) in group 1 were significantly higher than in group 2 (301.5 ± 55.8 vox, р < 0.05 and 9.1 ± 1.6 vox,р < 0,05, respectively). The patients with osmotic airway hyperresponsiveness also showed higher values of the expiratory area in the middle zone (235.3 ± 29.4 and 149.2 ± 14.9 pix, respectively; p = 0.00 47) and the lower zone (292.3 ± 37.9 and 178.6 ± 18.6 pix, respectively; p = 0.0034) of the lungs.Conclusion. Asthma patients with osmotic airway hyperresponsiveness have lung hyperinflation with impaired lung ventilation predominantly in the middle and lower zones.

Insights Into Acute and Delayed Cisplatin-Induced Emesis From a Microelectrode Array, Radiotelemetry and Whole-Body Plethysmography Study of Suncus murinus (House Musk Shrew)

Purpose: Cancer patients receiving cisplatin therapy often experience side-effects such as nausea and emesis, but current anti-emetic regimens are suboptimal. Thus, to enable the development of efficacious anti-emetic treatments, the mechanisms of cisplatin-induced emesis must be determined. We therefore investigated these mechanisms in Suncus murinus, an insectivore that is capable of vomiting.Methods: We used a microelectrode array system to examine the effect of cisplatin on the spatiotemporal properties of slow waves in stomach antrum, duodenum, ileum and colon tissues isolated from S. murinus. In addition, we used a multi-wire radiotelemetry system to record conscious animals’ gastric myoelectric activity, core body temperature, blood pressure (BP) and heart rate viability over 96-h periods. Furthermore, we used whole-body plethysmography to simultaneously monitor animals’ respiratory activity. At the end of in vivo experiments, the stomach antrum was collected and immunohistochemistry was performed to identify c-Kit and cluster of differentiation 45 (CD45)-positive cells.Results: Our acute in vitro studies revealed that cisplatin (1–10 μM) treatment had acute region-dependent effects on pacemaking activity along the gastrointestinal tract, such that the stomach and colon responded oppositely to the duodenum and ileum. S. murinus treated with cisplatin for 90 min had a significantly lower dominant frequency (DF) in the ileum and a longer waveform period in the ileum and colon. Our 96-h recordings showed that cisplatin inhibited food and water intake and caused weight loss during the early and delayed phases. Moreover, cisplatin decreased the DF, increased the percentage power of bradygastria, and evoked a hypothermic response during the acute and delayed phases. Reductions in BP and respiratory rate were also observed. Finally, we demonstrated that treatment with cisplatin caused inflammation in the antrum of the stomach and reduced the density of the interstitial cells of Cajal (ICC).Conclusion: These studies indicate that cisplatin treatment of S. murinus disrupted ICC networking and viability and also affected general homeostatic mechanisms of the cardiovascular system and gastrointestinal tract. The effect on the gastrointestinal tract appeared to be region-specific. Further investigations are required to comprehensively understand these mechanistic effects of cisplatin and their relationship to emesis.

Respiratory muscle strength in patients after COVID-19

Respiratory muscles (RM) are a very important part of the respiratory system that enables pulmonary ventilation. This study aimed to assess the post-COVID-19 strength of RM by estimating maximum static inspiratory (MIP or PImax) and expiratory (MEP or PEmax) pressures and to identify the relationship between MIP and MEP and the parameters of lung function. We analyzed the data of 36 patients (72% male; median age 47 years) who underwent spirometry, and body plethysmography, diffusion test for carbon monoxide (DLCO) and measurement of MIP and MEF. The median time between the examinations and onset of COVID-19 was 142 days. The patients were divided into two subgroups. In subgroup 1, as registered with computed tomography, the median of the maximum lung tissue damage volume in the acute period was 27%, in subgroup 2 it reached 76%. The most common functional impairment was decreased DLCO, detected in 20 (55%) patients. Decreased MIP and MEP were observed in 5 and 11 patients, respectively. The subgroups did not differ significantly in MIP and MEP values, but decreased MIP was registered in the second subgroup more often (18%). There were identified no significant dependencies between MIP/MEP and the parameters of ventilation and pulmonary gas exchange. Thus, in patients after COVID-19, MIP and MEP were reduced in 14 and 31% of cases, respectively. It is reasonable to add RM tests to the COVID-19 patient examination plan in order to check them for dysfunction and carry out medical rehabilitation.

Evaluation of a mechanical lung model to test small animal whole body plethysmography

Whole-body plethysmography (WBP) is an established method to determine physiological parameters and pathophysiological alteration of breathing in animals and animal models of a variety of diseases. Although frequently used, there is ongoing debate about what exactly is measured by whole-body-plethysmography and how reliable the data derived from this method are. Here, we designed an artificial lung model that enables a thorough evaluation of different predictions about and around whole-body plethysmography. Using our lung model, we confirmed that during WBP two components contribute to the pressure changes detected in the chamber: (1) the increase in the pressure due to heating and moistening of the air during inspiration, termed conditioning; (2) changes in the chamber pressure that depend on airway resistance. Both components overlap and contribute to the temporal pressure-profile measured in the chamber or across the wall of the chamber, respectively. Our data showed that a precise measurement of the breathing volume appears to be hindered by at least two factors: (1) the unknown relative contribution of each of these two components; (2) not only the air in the inspired volume is conditioned during inspiration, but also air within the residual volume and dead space that is recruited during inspiration. Moreover, our data suggest that the expiratory negative pressure peak that is used to determine the enhanced pause (Penh) parameter is not a measure for airway resistance as such but rather a consequence of the animal’s response to the airway resistance, using forced or active expiration to overcome the resistance by a higher thoracic pressure.

Automated Classification of Whole Body Plethysmography Waveforms to Quantify Breathing Patterns

Whole body plethysmography (WBP) monitors respiratory rate and depth but conventional analysis fails to capture the diversity of waveforms. Our first purpose was to develop a waveform cluster analysis method for quantifying dynamic changes in respiratory waveforms. WBP data, from adult Sprague-Dawley rats, were sorted into time domains and principle component analysis was used for hierarchical clustering. The clustering method effectively sorted waveforms into categories including sniffing, tidal breaths of varying duration, and augmented breaths (sighs). We next used this clustering method to quantify breathing after opioid (fentanyl) overdose and treatment with ampakine CX1942, an allosteric modulator of AMPA receptors. Fentanyl caused the expected decrease in breathing, but our cluster analysis revealed changes in the temporal appearance of inspiratory efforts. Ampakine CX1942 treatment shifted respiratory waveforms toward baseline values. We conclude that this method allows for rapid assessment of breathing patterns across extended data recordings. Expanding analyses to include larger portions of recorded WBP data may provide insight on how breathing is affected by disease or therapy.

Functional methods of investigation of respiratory system in asthma

The article deals with the application of functional methods for the study of the respiratory system, such as spirometry, bronchodilatation test, stress testing to detect bronchial hyperreactivity, provocative test with metacholine, impulse oscillometry, body plethysmography for the diagnosis, following up and prediction of the course of asthma.