Inspiratory Volume Research Articles

Multidimensional breathlessness response to exercise: Impact of COPD and healthy ageing

This study compared the multidimensional breathlessness response to incremental cardiopulmonary cycle exercise testing (CPET) in people with chronic obstructive pulmonary disease (COPD; n = 14, aged 69 ± 9 years, forced expiratory volume in 1-sec = 54 ± 16 % predicted) and healthy older (OA) (n = 35, aged 68 ± 5 years) and younger (YA) (n = 19, aged 28 ± 8 years) adults. Participants performed CPET and successively rated overall breathlessness intensity, unsatisfied inspiration, breathing too shallow, work/effort of breathing, and breathlessness-related unpleasantness, fear, and anxiety using the 0−10 Borg scale. At any given percent predicted peak minute ventilation, people with COPD rated all breathlessness sensations higher than OA and YAs, who were similar. Most between group differences disappeared when examined in relation to inspiratory reserve volume, except people with COPD reported higher levels of unsatisfied inspiration and breathing too shallow (vs YA), and breathlessness-related fear and anxiety (vs OA and YAs). Multidimensional ratings of breathlessness sensations during CPET provides further insight into differences in exertional symptom perceptions among people with COPD and without COPD.

Diaphragmatic excursion: Quantitative measure to assess adequacy of expiratory phase CT chest images

ObjectiveTo evaluate diaphragmatic excursion as a quantitative metric for change in lung volume between inspiratory and expiratory chest computed tomography (CT) images. MethodsA 12-month retrospective review identified 226 chest CT exams with inspiratory and expiratory phase imaging, 63 in individuals referred with diagnosis of asthma by ICD9/10 code. Exams acquired in the supine position at 1.25 mm slice thickness in each phase were included (n = 30, mean age = 62, M = 15, F = 15). Diaphragmatic excursion was calculated as the difference between axial slices through the lungs on inspiration and expiration, using the lung apex as the cranial bound, and the hemidiaphragm caudally. Inspiratory and expiratory lung and tracheal volumes were calculated through volumetric segmentation. Tracheal morphology was assessed at 1 cm above the level of the aortic arch, and 1 cm above the carina. ResultsInspiratory and expiratory lung volumes were higher in men (mean I = 5 + 1.6 L, E = 3.1 + 1.2 L) than women (mean I = 3.6 + 0.8 L, E = 2.4 + 0.7 L), p = .005 and p = .047, respectively. Average inspiratory and expiratory tracheal volumes were higher in men (I = 61 + 17 mL, E = 43 + 14) than women (I = 44 + 14, E = 30 + 8), p = .006 and p = .005. Average change in lung and tracheal volume between inspiratory and expiratory scans did not significantly differ between men and women. Average diaphragmatic excursion was 2.5 cm between inspiratory and expiratory scans (2.7 cm in men, 2.3 cm in women; p = .5). There was a strong positive correlation between diaphragmatic excursion and change in lung (r = .84) and tracheal volume (r = .79). A moderate correlation was also found between change in tracheal volume and change in lung volume (r = 0.67). Change in tracheal morphology between inspiratory and expiratory imaging was associated with change in tracheal volume at both 1 cm above the aortic arch (p = .04) and 1 cm above the carina (p = .008); there was no association with diaphragmatic excursion or lung volume. ConclusionsDiaphragmatic excursion is a quantitative measure of expiratory effort as validated by both lung and tracheal volumes in asthma patients, and may be more accurate than qualitative assessment based on tracheal morphology.

Heliox administration in anesthetized rabbits with spontaneous inspiratory flow limitation.

We investigated the effects of heliox administration (80% helium in O2) on tidal inspiratory flow limitation (tIFL) occurring in supine anesthetized spontaneously breathing rabbits, regarded as an animal model of obstructive apnea-hypopnea syndrome. 22 rabbits were instrumented to record oro-nasal mask flow, airway opening, tracheal and esophageal pressures, and diaphragm and genioglossus electromyographic activities while breathing either room air or heliox, and, in 12 rabbits, also during the application of continuous positive airway pressure (CPAP; 6 cmH2O). For the group, heliox increased peak inspiratory flow, ventilation (18 ± 11%), peak inspiratory tracheal and dynamic transpulmonary pressures, but in no animal eliminated tIFL, as instead CPAP did in all. Muscle activities were unaffected by heliox. In the presence of IFL the increase in flow with heliox (ΔV̇ifl) varied markedly among rabbits (2 to 49%), allowing the distinction between responders and non-responders. None of the baseline variables discriminated responders and non-responders. However, fitting the Rohrer equation (R=K1 + K2V̇) to the tracheal pressure-flow relationship over the first 0.1 s of inspiration while breathing air allowed such discrimination on the basis of larger K2 in responders (0.005 ± 0.002 versus 0.002 ± 0.001 cmH2O·s2·ml-2; P < 0.001), suggesting a corresponding difference in the relative contribution of laminar and turbulent flow. The differences in ΔV̇ifl between responders and non-responders were simulated by modeling the collapsible segment of the upper airways as a non-linear resistor and varying its pressure-volume curve, length, and diameter, thus showing the importance of mechanical and geometrical factors in determining the response to heliox in the presence of tIFL.NEW & NOTEWORTHY In an obstructive sleep apnea rabbit model, heliox never abolishes tidal inspiratory flow limitation (IFL), but increases inspiratory flow and tidal volume, substantially in some and nearly nil in other animals. Positive response to heliox cannot be predicted on the basis of breathing pattern characteristics or upper airway resistance that preceded IFL onset, but is related to the mechanical and geometrical features of upper airway collapsible segment, as indicated by model simulation.

Average volume-assured pressure support vs conventional bilevel pressure support in pediatric nocturnal hypoventilation: a case series.

Average volume-assured pressure support (AVAPS) is a modality of noninvasive ventilation that provides a targeted tidal volume by automatically adjusting the inspiratory pressure support within a set range. Pediatric studies evaluating the efficacy of AVAPS in treating nocturnal hypoventilation are confined to case reports. The aim of this study was to compare AVAPS to conventional bilevel positive airway pressure (BPAP) support in improving hypercarbia in a cohort of pediatric patients with nocturnal hypoventilation. Retrospective review of patient records at an established tertiary pediatric sleep laboratory over a 6-year period. Ventilatory and sleep study parameters from AVAPS and conventional BPAP titration studies were compared. AVAPS was used only if hypoventilation was not controlled using conventional BPAP. Inspiratory pressures, tidal volumes, and adherence were downloaded on final titrated ventilatory settings. Comparisons were made using paired t test. A total of 19 patients (11 boys, 8 girls; median age 10.5 years, range 1 to 20 years) were identified. Diagnoses included neuromuscular disease (n = 9), obstructive hypoventilation (n = 5), parenchymal lung disease (n = 4), and congenital central hypoventilation syndrome (n = 2). AVAPS demonstrated significant improvement in peak (P = .009) and mean (P = .001). Transcutaneous CO₂ parameters compared to conventional bilevel. Oxygenation on AVAPS showed positive trend but did not reach statistical significance. AVAPS delivered higher tidal volumes (P = .04) using similar pressures. There was no statistically significant difference in obstructive apnea-hypopnea index, respiratory arousal index, sleep efficiency, and adherence between AVAPS and conventional BPAP. AVAPS was an effective alternative to conventional BPAP in improving hypercarbia in our selective cohort of pediatric patients. Prospective, longitudinal studies are needed to evaluate the benefits of AVAPS feature in the pediatric population.

Minimal Lung Mechanics Basis-functions for a Mechanical Ventilation Virtual Patient

Abstract Mechanical ventilation (MV) is used in the intensive care unit (ICU) to treat patients with respiratory failure. However, MV settings are not standardized due to significant inter- and intra- patient variability in response to care, leading to variability in care, outcome, and cost. There is thus a need to personalize MV. This research extends a single compartment lung mechanics model with physiologically relevant basis functions, to identify patient-specific lung mechanics and predict response to changes in MV care. The nonlinear evolution of pulmonary elastance as positive-end-expiratory pressure (PEEP) changes is captured by a physiologically relevant, simplified compensatory equation as a function of PEEP and pressure identification error at the baseline PEEP level. It allows both patient-specific and general prediction of lung elastance of higher PEEP. The prediction outcome is validated with data from two volume-controlled ventilation (VCV) trials and one pressure-controlled ventilation (PCV) trial, where the biggest PEEP prediction interval is a clinically unrealistic 20cmH2O, comprising 210 prediction cases over 36 patients (22 VCV; 14 PCV). Predicted absolute peak inspiratory pressure (PIP) errors are within 1.0cmH2O and 3.3cmH2O for 90% cases in the two VCV trials, while predicted peak inspiratory tidal volume (PIV) errors are within 0.073L for 85% cases in studied PCV trial. The model presented provides a highly accurate, predictive virtual patient model across multiple MV modes and delivery methods, and over clinically unrealistically large changes. Low computational cost, and fast, easy parameterization enable model-based, predictive decision support in real-time to safely personalize and optimize MV care.

Regional lung function measures determined by electrical impedance tomography during repetitive ventilation manoeuvres in patients with COPD

Objective. Current standards for conducting spirometry examinations recommend that the ventilation manoeuvres needed in pulmonary function testing are carried out repeatedly during sessions. Chest electrical impedance tomography (EIT) can determine the presence of ventilation heterogeneity during such manoeuvres, which increases the information content derived from such examinations. The aim of this study was to characterise regional lung function in patients with chronic obstructive pulmonary disease (COPD) during repetitive forced full ventilation manoeuvres. Regional lung function measures derived from these manoeuvres were compared with quiet tidal breathing. Approach. Sixty hospitalised patients were examined during up to three repeated ventilation manoeuvres. Acceptable spirometry manoeuvres were performed and EIT recordings suitable for analysis obtained in 53 patients (12 women, 41 men; age: 68 ± 12 years (mean ± SD)). Pixel values of tidal volume, forced full inspiratory and expiratory volume in 1 s, and forced inspiratory and expiratory vital capacity were calculated from the EIT data. Spatial ventilation heterogeneity was assessed using the coefficient of variation, global inhomogeneity index, and centres and regional fractions of ventilation. Temporal inhomogeneity was determined by examining the pixel expiration times needed to exhale 50% and 75% of regional forced vital capacity. Main results. All EIT-derived measures of regional lung function showed reproducible results during repetitive examinations. Parameters of spatial heterogeneity obtained from quiet tidal breathing were comparable with the measures derived from the forced manoeuvres. Significance. Measures of spatial and temporal ventilation heterogeneity obtained in COPD patients by EIT provide comparable findings during repeated examinations within one testing session. Quiet tidal breathing generates similar information on ventilation heterogeneity as forced manoeuvres that demand a high amount of patient effort.

Virtual patients for mechanical ventilation in the intensive care unit

BackgroundMechanical ventilation (MV) is a core intensive care unit (ICU) therapy. Significant inter- and intra- patient variability in lung mechanics and condition makes managing MV difficult. Accurate prediction of patient-specific response to changes in MV settings would enable optimised, personalised, and more productive care, improving outcomes and reducing cost. This study develops a generalised digital clone model, or in-silico virtual patient, to accurately predict lung mechanics in response to changes in MV. MethodsAn identifiable, nonlinear hysteresis loop model (HLM) captures patient-specific lung dynamics identified from measured ventilator data. Identification and creation of the virtual patient model is fully automated using the hysteresis loop analysis (HLA) method to identify lung elastances from clinical data. Performance is evaluated using clinical data from 18 volume-control (VC) and 14 pressure-control (PC) ventilated patients who underwent step-wise recruitment maneuvers. ResultsPatient-specific virtual patient models accurately predict lung response for changes in PEEP up to 12 cmH2O for both volume and pressure control cohorts. R2 values for predicting peak inspiration pressure (PIP) and additional retained lung volume, Vfrc in VC, are R2=0.86 and R2=0.90 for 106 predictions over 18 patients. For 14 PC patients and 84 predictions, predicting peak inspiratory volume (PIV) and Vfrc yield R2=0.86 and R2=0.83. Absolute PIP, PIV and Vfrc errors are relatively small. ConclusionsOverall results validate the accuracy and versatility of the virtual patient model for capturing and predicting nonlinear changes in patient-specific lung mechanics. Accurate response prediction enables mechanically and physiologically relevant virtual patients to guide personalised and optimised MV therapy.

In Vitro Evaluation of Facial Pressure and Air Leak with a Newly Designed Cushion for Non-Invasive Ventilation Masks.

Background: The aim of this study was to evaluate the effect of a newly designed foam cushion on the air leakage and pressure when applied to the face. Methods: A teaching manikin connected to a bilevel positive airway pressure ventilator attached to four different brands of oronasal masks (Amara, Mirage, Forma, and Wizard) was used. The foam cushions of 5-mm and 10-mm-thickness were attached to the masks, and each mask was tested without a cushion. Six pressure sensors were placed on the manikin’s face, and data were recorded. Inspiratory volume and air leak flow from the ventilator were observed. Results: Air leakage was influenced by both the mask brand and the presence of a cushion. The presence of a cushion did not affect the Wizard mask in terms of leakage (p = 0.317) or inspiratory volume (p = 0.726). The Wizard and Amara masks generated the lowest contact pressure on the frontal forehead (p < 0.001) compared to the other five points. Conclusions: Utilisation of a cushion reduces air leakage and maintains greater inspiratory volume regardless of its thickness. The contact pressure varies depending on the brand of the mask, which would require a difference in the thickness of the cushion for pressure reduction.

Patient Inspiratory Maneuver Performance; Peak Lungpower, Acceleration and Volume.

Background: Use of drug delivery devices between nebulizers, dry powder inhalers (DPIs), or metered dose inhalers (MDIs), for treating patients with asthma and chronic obstructive pulmonary disease (COPD), is based on patients' capability of coordinating the inhalation maneuver and achieving sufficient airflow. There are limited data available with regard to how patients meet the requirements of successful inhalation performance, and how the concept of inspiratory lungpower could be applied. The aim of this work was to study the patient inspiratory airflow profile performance in large data sets. We analyzed how the Kamin-Haidl inhalation criteria were met by patients with DPIs such as Easyhaler for combination therapy (EH-combi), Easyhaler for monotherapy (EH-mono), Diskus, and Turbuhaler (TH), and applied peak lungpower instead of peak inspiratory flow rate as an indicator of patient performance.Materials and Methods: Data sets gathered in two previous studies for DPIs, that is, EH-combi, EH-mono, Diskus, and TH, were used to analyze how inspiratory lungpower representing inspiratory muscle power, flow acceleration, and volume after peak met the inhalation criteria. The measured patient airflow profiles through inhalers were assessed for patients with asthma or COPD.Results: Based on the Kamin-Haidl inhalation criteria, successful inhalation requirements were met with EH-combi in 96.1% and with EH-mono in 92.6% of patients. The success rates were 89.5% and 84.6% with Diskus and TH, respectively, (p < 0.0001 between devices). In patients with asthma or COPD, the mean lungpower was 7.51 and 6.15 W for EH-combi, 8.79 and 6.88 W for EH-mono, 7.18 and 4.36 W for Diskus, and 9.65 and 6.86 W for TH, respectively, when patients followed the manufacturer's written instructions.Conclusions: Lungpower applied to the Kamin-Haidl inhalation criteria concept could be an applicable method for reviewing patient performance for different DPIs despite DPIs' characteristic differences in airflow resistance. In light of these results, DPIs provide a feasible treatment option for a large majority of respiratory patients.

Effect of obesity on lung function test among adults

Background: Obesity is a chronic disease characterized by excessive body fat that causes damage to the individual’s health and is associated with comorbidities such as diabetes and hypertension and vascular dysfunction. This cross-sectional study was carried out with the objective of evaluating the effect of obesity on lung function test in obese but otherwise healthy adults.Methods: It was a cross-sectional study carried out at tertiary care institute of Gujarat, India. It was conducted over a period of 5 months. A total of 240 adult healthy subjects of both sexes were selected randomly belonging to varying socio-economic status. The study subjects were divided into 3 categories (normal body mass index i.e. BMI, overweight, obese). BMI were calculated for the randomly selected subjects from each list till the desired number in each BMI group were attained. Four respiratory parameters viz. forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), forced expiratory volume in 3 seconds (FEV3), and maximum voluntary ventilation (MVV) were used to assess their lung functions.Results: Two hundred and forty subjects (each group having n=80). The mean age of group I, group II and group III were 27.45±6.37, 28.18±6.42 and 28.98±6.74 respectively. Lung volumes showed significant difference in relation to the BMI. FVC and FEV1 show significant decrease. Group III verses group I (p˂0.001 and p˂0.017 respectively) FEV3 showed significant difference between group I and group III and between group II and group III (p˂0.001). MVV was significantly lower in group III when compared to group I.Conclusions: There is decline in pulmonary function in obese as compared to normal weight adults. These findings suggest deleterious effects on ventilatory mechanics caused by obesity, due to probable lung compression (reduction in the expiratory reserve volume i.e. ERV), leading to a compensatory increase in the inspiratory reserve volume (IRV) in an attempt to maintain a constant vital capacity (VC).

Cinesiterapia respiratória no doente crítico com covid-19: a intervenção do enfermeiro de reabilitação - estudo de caso

Objetivo: Desconhece-se de que forma a COVID- 19 condiciona a intervenção do enfermeiro de reabilitação em unidades de cuidados intensivos. Este estudo tem como objetivo: descrever as intervenções do enfermeiro de reabilitação em termos de Cinesiterapia Respiratória na pessoa com COVID-19, com ventilação mecânica e em venovenous extracorporeal membrane oxygenation, analisando a resposta em termos de parâmetros gasométricos e ventilatórios antes e após cada sessão. Método: Estudo de caso de uma pessoa com 63 anos, com antecedentes de obesidade e hipertensão arterial. Realizou-se colheita de dados retrospetiva de processo clínico, referente a um período de internamento em UCI de 38 dias. Resultados: As técnicas mais utilizadas na Cinesiterapia Respiratória foram a aspiração de secreções em circuito fechado, vibrações, descompressão brusca, aberturas costais seletivas, expiração manual forçada, ventilação dirigida e in-exsuflador mecânico. Na globalidade das sessões, verificou-se uma melhoria nos volumes inspiratórios e expiratórios, assim como melhoria na compliance estática. Começou a usar-se o in-exsuflador mecânico ao fim de uma semana de internamento, depois de se esgotarem todas as 2 intervenções possíveis, sendo que todos os outcomes apresentaram melhorias globais, sem eventos de segurança. Conclusão: A implementação de um programa estruturado e individualizado de cinesiterapia respiratória, pode contribuir significativamente na recuperação da pessoa em situação crítica, tendo-se usado com eficácia técnicas que não estavam descritas para casos COVID- 19. Palavras-chave: Cinesiterapia Respiratória; COVID-19; ventilação mecânica; Enfermeiro Reabilitação; ECMOVV; in-exsuflador mecânico.

Comparison of Aerodynamic Characteristics During Reading Paragraph Tasks in Normal Male and Female Adults

Purpose: The present study was performed to compare the aerodynamic characteristics of males and females during reading paragraph task.Methods: Thirty-seven normal adult males (18-30 yrs) and thirty-nine normal adult females (18-34 yrs) were participated in this experiment. They read a part of ‘Gaeul’ paragraph with comfortable phonation, and the reading samples were recorded and analyzed by ‘Running Speech’ program of Phonatory Aerodynamic System (PAS).Results: Phonation time (with voicing) and expiratory airflow duration were significantly longer in females, but measures of inspiratory airflow duration, peak expiratory airflow, expiratory and inspiratory volumes were significantly higher in males. The difference in total duration and peak inspiratory airflow did not show statistical significance.Conclusion: Results revealed that there was a significant gender difference in aerodynamic measures of duration and airflow during the reading paragraph task. In evaluating and intervening aerodynamics of voice and voice disorder patients, we should also consider the gender-different aerodynamic characteristics in continuous speech.

Improvement in Lung Insufflation in Spontaneously Breathing Tracheostomized Patients by Using a New Pulmonary Expansion Device: A Pilot Study

Abstract Lung expansion techniques (LETs) are a key component of pulmonary rehabilitation. Nevertheless, these can be limited in tracheostomized patients because of the infraglottic position of tracheostomy cannulas. We propose a novel pulmonary expansion device (PED) that allows deep inspiration with a postinspiratory pause for a few seconds by means of a unidirectional valve and an occlusion/flow release cap. It is equipped with a relief valve that opens at 60 cm H2O in cases in which this threshold is attained. We aimed to evaluate the impact on lung volume and pressure in spontaneously breathing tracheostomized patients subjected to LETs. A single-arm pilot interventional study was conducted in an adult intensive care unit (ICU), including spontaneously breathing tracheostomized patients. 80 treatments were performed on 10 patients with tracheostomies with PED over a period of 3 months. The maximal inspiratory volume (MIV) was significantly increased by using PED (MIV-PED) at both day 1 (725 (600–820) mL versus 1550 (1250–1700) mL, P &amp;lt; 0.001) and day 3 (870 (750–950) mL versus 1662 (1550–1900) mL, P &amp;lt; 0.001). Inspiratory pause pressure (PIP-PED) did not significantly change from day 1 to day 3 (18 (14–20) cm H2O versus 14 (12–22) cm H2O, P = 0.36). The use of the PED in tracheostomy patients acted as an artificial glottis by performing a novel pulmonary re-expansion maneuver, and increased volumes and intrapulmonary pressure with prolongation of maximum inspiration were achieved.

An Analysis of the Impact of Different Levels of Inspiratory Volume Using Active Breathing Control on the Intrafraction Motion and Dose Coverage of Target Volumes in Patients Undergoing Thoracic Radiotherapy

To determine whether the level of inspiratory volume affect the extent to which active breathing control (ABC) reduces intrafraction motion and affect the dose coverage of target volumes in patients receiving external beam radiation therapy (EBRT) to the thoracic region. This is a prospective study involving 20 patients undergoing thoracic radiotherapy using ABC for respiratory motion management and volumetric modulated arc therapy (VMAT) as the treatment technique. They will be randomized to one of two groups. The first will be the control group of 80% inspiratory volume and the other test group will be 70%. At least one set of repeated CBCTs will be done weekly. All images including CBCTs and Planning CTs will be sent to commercially available software for analysis of intrafraction motion using Dice Similarity Coefficient (DSC) and determination of systematic and random errors. The target dose conformality will be assessed using conformation number (CN). Intention-to-treat analysis will be employed for statistical purpose. The DSC for the 70% and 80% inspiratory volume group was 0.93 and 0.92, respectively. For the 70% group, there was a significant negative correlation (p<0.05) between DSC and time between two CBCTs, but not for the 80% group. The superior-inferior (SI) direction was the highest among the systematic and random translational errors. The rotational systematic and random errors appear to be slightly less for the 80% group compared to the 70% group. The average percentage change in CN for the 70% and 80% group was 10.91% and 8.14%, respectively. Their difference was significant using Mann Whitney-U test (p<0.05). Furthermore, the actual change in volume had a significant positive correlation (p<0.05) with the percentage change in CN for the 70% inspiratory volume group but not the 80% group using Spearman’ s correlation. Last but not least, there was no significant difference for the change in CN when the change in volume is greater than 0.05L or less than or equal to 0.05L for either group of patients. There is more evidence suggesting the target volumes from the 80% inspiratory volume group have less intrafraction motion compared to the 70% inspiratory volume group. The findings from the calculation of CN suggest that there could potentially be less tumor motion for higher levels of inspiratory volume and this could possibly contribute to why intrafraction motion is less for the 80% inspiratory volume group. The 0.1L over the reference volume used at the author’s department is feasible in terms of not leading to a significant increase in the change in CN.

Comparison of inspiratory and expiratory lung and lobe volumes among supine, standing, and sitting positions using conventional and upright CT

Currently, no clinical studies have compared the inspiratory and expiratory volumes of unilateral lung or of each lobe among supine, standing, and sitting positions. In this prospective study, 100 asymptomatic volunteers underwent both low-radiation-dose conventional (supine position, with arms raised) and upright computed tomography (CT) (standing and sitting positions, with arms down) during inspiration and expiration breath-holds and pulmonary function test (PFT) on the same day. We compared the inspiratory/expiratory lung/lobe volumes on CT in the three positions. The inspiratory and expiratory bilateral upper and lower lobe and lung volumes were significantly higher in the standing/sitting positions than in the supine position (5.3–14.7% increases, all P < 0.001). However, the inspiratory right middle lobe volume remained similar in the three positions (all P > 0.15); the expiratory right middle lobe volume was significantly lower in the standing/sitting positions (16.3/14.1% decrease) than in the supine position (both P < 0.0001). The Pearson’s correlation coefficients (r) used to compare the total lung volumes on inspiratory CT in the supine/standing/sitting positions and the total lung capacity on PFT were 0.83/0.93/0.95, respectively. The r values comparing the total lung volumes on expiratory CT in the supine/standing/sitting positions and the functional residual capacity on PFT were 0.83/0.85/0.82, respectively. The r values comparing the total lung volume changes from expiration to inspiration on CT in the supine/standing/sitting positions and the inspiratory capacity on PFT were 0.53/0.62/0.65, respectively. The study results could impact preoperative CT volumetry of the lung in lung cancer patients (before lobectomy) for the prediction of postoperative residual pulmonary function, and could be used as the basis for elucidating undetermined pathological mechanisms. Furthermore, in addition to morphological evaluation of the chest, inspiratory and expiratory upright CT may be used as an alternative tool to predict lung volumes such as total lung capacity, functional residual capacity, and inspiratory capacity in situation in which PFT cannot be performed such as during an infectious disease pandemic, with relatively more accurate predictability compared with conventional supine CT.

The feasibility of eucapnic voluntary hyperpnoea for the diagnosis of exercise-induced bronchoconstriction in a community pulmonary practice

Objective Exercise-induced bronchoconstriction (EIB) is a common condition and is typically treated empirically based on symptoms alone. However, symptoms of EIB are typically nonspecific. Objective testing with eucapnic voluntary hyperpnea (EVH) is a sensitive and specific method to diagnose EIB and may suggest alternative etiologies such as exercise-induced laryngeal obstruction (EILO). To this point, EVH has been primarily utilized in large academic centers and in elite athletes. We intend to discuss the feasibility and clinical application of utilizing EVH to diagnose EIB in a community-based pulmonary practice. Methods Retrospective analysis of 62 patients who completed EVH at The Oregon Clinic Pulmonary Clinic. Patients with inspiratory flow volume loop flattening or clinical symptoms were assessed by otolaryngology for evidence of EILO. Results: 61 of 62 patients were included in the final analysis. 52 of 61 patients (85%) achieved an interpretable test with a maximum voluntary ventilation (MVV) >60%. There was no difference in baseline spirometry or patient characteristics between those who were able to reach an MVV >60% and those who did not. 14 (23%) patients were diagnosed with EIB, 18 (30%) with EILO, and 4 (7%) were diagnosed with both EIB and EILO. Only 1 patient had a non-diagnostic evaluation with MVV <60% and negative for EIB and EILO. Conclusions EVH is a feasible diagnostic modality to evaluate for EIB in a community pulmonary practice and may suggest alternative conditions such as EILO. Accurate diagnosis is paramount to prescribing proper therapy, decreasing inappropriate medication use, and relieving exercise-induced symptoms.

Variability of Voluntary Cough Airflow in Healthy Adults and Parkinson's Disease.

Cough is an important airway protective behavior responsible for ejecting material from the airway to prevent pneumonia, a leading cause of death in older adults and individuals with Parkinson's disease (PD). Variability of motor performance for both spinal and bulbar functions has been documented; however, there are no studies examining variability of cough motor control in PD and healthy controls. The present study examined the effects of age and PD on variability of voluntary cough performance. Twenty-five healthy younger adults (HYA), 26 healthy older adults (HOA), and 16 participants with PD completed three trials of sequential voluntary cough with spirometry. Coefficients of variation were used to examine variability between groups. Increased variability of cough expired volume (p = 0.012) and inspiratory volume (p = 0.006) was appreciated in HOAs compared to HYAs. Participants with PD demonstrated increased variability of cough expired volume (p = 0.029), peak expiratory flow rise time (p = 0.016), and cough volume acceleration (p = 0.034) compared to HOAs. Though participants with PD descriptively demonstrated increased peak expiratory flow rate compared to HOAs, this finding was statistically nonsignificant after adjusting for multiple comparisons (p = 0.072). This study identified that variability in cough airflow increases in healthy aging and Parkinson's disease. These motor control impairments may be attributed to age and disease-related sensorimotor changes in the peripheral and central nervous system. Future research will be necessary to examine the relationship between inconsistent cough motor output, airway invasion, and aspiration pneumonia in PD.

Real-Time Effort Driven Ventilator Management: A Pilot Study.

Mechanical ventilation of patients with acute respiratory distress syndrome should balance lung and diaphragm protective principles, which may be difficult to achieve in routine clinical practice. Through a Phase I clinical trial, we sought to determine whether a computerized decision support-based protocol (real-time effort-driven ventilator management) is feasible to implement, results in improved acceptance for lung and diaphragm protective ventilation, and improves clinical outcomes over historical controls. Interventional nonblinded pilot study. PICU. Mechanically ventilated children with acute respiratory distress syndrome. A computerized decision support tool was tested which prioritized lung-protective management of peak inspiratory pressure-positive end-expiratory pressure, positive end-expiratory pressure/FIO2, and ventilatory rate. Esophageal manometry was used to maintain patient effort in a physiologic range. Protocol acceptance was reported, and enrolled patients were matched 4:1 with respect to age, initial oxygenation index, and percentage of immune compromise to historical control patients for outcome analysis. Thirty-two patients were included. Acceptance of protocol recommendations was over 75%. One-hundred twenty-eight matched historical controls were used for analysis. Compared with historical controls, patients treated with real-time effort-driven ventilator management received lower peak inspiratory pressure-positive end-expiratory pressure and tidal volume, and higher positive end-expiratory pressure when FIO2 was greater than 0.60. Real-time effort-driven ventilator management was associated with 6 more ventilator-free days, shorter duration until the first spontaneous breathing trial and 3 fewer days on mechanical ventilation among survivors (all p ≤ 0.05) in comparison with historical controls, while maintaining no difference in the rate of reintubation. A computerized decision support-based protocol prioritizing lung-protective ventilation balanced with reduction of controlled ventilation to maintain physiologic levels of patient effort can be implemented and may be associated with shorter duration of ventilation.

Do manual chest compressions provide substantial ventilation during prehospital cardiopulmonary resuscitation?

Chest compressions have been suggested to provide passive ventilation during cardiopulmonary resuscitation. Measurements of this passive ventilatory mechanism have only been performed upon arrival of out-of-hospital cardiac arrest patients in the emergency department. Lung and thoracic characteristics rapidly change following cardiac arrest, possibly limiting the effectiveness of this mechanism after prolonged resuscitation efforts. Goal of this study was to quantify passive inspiratory tidal volumes generated by manual chest compression during prehospital cardiopulmonary resuscitation. A flowsensor was used during adult out-of-hospital cardiac arrest cases attended by a prehospital medical team. Adult, endotracheally intubated, non-traumatic cardiac arrest patients were eligible for inclusion. Immediately following intubation, the sensor was connected to the endotracheal tube. The passive inspiratory tidal volumes generated by the first thirty manual chest compressions performed following intubation (without simultaneous manual ventilation) were calculated. 10 patients (5 female) were included, median age was 64years (IQR 56, 77years). The median compression frequency was 111 compression per minute (IQR 107, 116 compressions per minute). The median compression depth was 5.6cm (IQR 5.4cm, 6.1cm). The median inspiratory tidal volume generated by manual chest compressions was 20mL (IQR 13, 28mL). Using a flowsensor, passive inspiratory tidal volumes generated by manual chest compressions during prehospital cardiopulmonary resuscitation, were quantified. Chest compressions alone appear unable to provide adequate alveolar ventilation during prehospital treatment of cardiac arrest.

Ultrasound-guided supraclavicular vs. retroclavicular block of the brachial plexus: comparison of ipsilateral diaphragmatic function: A randomised clinical trial.

The ultrasound-guided retroclavicular block (RCB) is a recently described alternative approach to brachial plexus blockade at the level of the cords. Although more distal blockade of the brachial plexus is thought to be associated with a lower incidence of phrenic nerve block, the impact of RCB on ipsilateral diaphragmatic function has not been formally investigated. To compare the effects of supraclavicular and retroclavicular brachial plexus block on diaphragmatic function. A single tertiary hospital, study period from December 2017 to May 2019. Double-blinded, randomised study. A total of 40 patients undergoing upper extremity surgery below the axilla. Exclusion criteria included significant pulmonary disease, BMI more than 40 and contra-indication to peripheral nerve block. Patients were randomised to supraclavicular or retroclavicular brachial plexus block with ropivacaine 0.5%. Phrenic block was assessed by measuring changes in diaphragmatic excursion using M-mode ultrasound, and maximum inspiratory volume on incentive spirometry from baseline, at 15 and 30 min postblock, and postoperatively. Comparative assessment of block characteristics included timing and distribution of sensory and motor block onset in the upper extremity, and scanning and block performance times. The incidence of phrenic block in the supraclavicular group was higher by ultrasound imaging (70 vs. 15%) and also by pulmonary function testing (55 vs. 5%), with both diaphragmatic excursion and maximum inspiratory volume decreasing to a greater extent after supraclavicular block (SCB) compared with RCB at 15, 30 min and postoperative time points (repeated measures analysis of variance, P < 0.001). There was no difference in timing and extent of distal arm block, but suprascapular and axillary nerves were more consistently blocked after SCB than after RCB. The current study confirms the hypothesis that a RCB is significantly less likely to affect ipsilateral diaphragmatic function than a SCB. Clinicaltrials.gov identifier: NCT02631122.