Tidal Volume Values Research Articles

ИСКУССТВЕННАЯ ВЕНТИЛЯЦИЯ ЛЕГКИХ С ЦЕЛЕВЫМ ДЫХАТЕЛЬНЫМ ОБЪЕМОМ У НОВОРОЖДЕННЫХ И ДЕТЕЙ РАННЕГО ВОЗРАСТА С РАЗЛИЧНЫМИ ЗАБОЛЕВАНИЯМИ ЛЕГКИХ: ПРОТОКОЛ ПОДГОТОВКИ ДЫХАТЕЛЬНОГО АППАРАТА И УПРАВЛЕНИЯ ПАРАМЕТРАМИ ВЕНТИЛЯЦИИ

One of the leading trends in modern medicine is the principle of prevention, which consists in preventing the formation of diseases and complications of therapy. The main damaging factor during respiratory support in patients with inhomogeneous lung tissue injury is tidal volume (TV). With traditional pressure controlled mechanical ventilation (PCMV), controlling the TV delivered to the child is difficult due to the variable mechanical properties of the lung tissue. PCMV algorithms with targeted TV, used in neonatology and in young children, make it possible to adjust the parameters of endotracheal respiratory support automatically. Thus, the principle of prevention is observed from inspiration to inspiration, and TV values become more constant, despite the changing respiratory mechanics. This protects the lungs from volumotrauma and ensures favorable outcomes. The purpose of this work is to review the existing recommendations on the use of dual-control modes of ventilation in newborns and young children and to present a protocol for preparing the breathing apparatus and controlling parameters when using PCMV with guaranteed TV.

Lower Driving Pressure and Neuromuscular Blocker Use Are Associated With Decreased Mortality in Patients With COVID-19 ARDS.

The impact of mechanical ventilation parameters and management on outcomes of patients with coronavirus disease 2019 (COVID-19) ARDS is unclear. This multi-center observational study enrolled consecutive mechanically ventilated patients with COVID-19 ARDS admitted to one of 7 Korean ICUs between February 1, 2020-February 28, 2021. Patients who were age < 17 y or had missing ventilation parameters for the first 4 d of mechanical ventilation were excluded. Multivariate logistic regression was used to identify which strategies or ventilation parameters that were independently associated with ICU mortality. Overall, 129 subjects (males, 60%) with a median (interquartile range) age of 69 (62-78) y were included. Neuromuscular blocker (NMB) use and prone positioning were applied to 76% and 16% of subjects, respectively. The ICU mortality rate was 37%. In the multivariate analysis, higher dynamic driving pressure (ΔP) values during the first 4 d of mechanical ventilation were associated with increased mortality (adjusted odds ratio 1.16 [95% CI 1.00-1.33], P = .046). NMB use was associated with decreased mortality (adjusted odds ratio 0.27 [95% CI 0.09-0.81], P = .02). The median tidal volume values during the first 4 d of mechanical ventilation and the ICU mortality rate were significantly lower in the NMB group than in the no NMB group. However, subjects who received NMB for ≥ 6 d (vs < 6 d) had higher ICU mortality rate. In subjects with COVID-19 ARDS receiving mechanical ventilation, ΔP during the first 4 d of mechanical ventilation was independently associated with mortality. The short-term use of NMB facilitated lung-protective ventilation and was independently associated with decreased mortality.

Second-generation laryngeal mask airway as an alternative to endotracheal tube in prolonged laparoscopic abdominal surgery: a comparative analysis of intraoperative gas exchanges.

Laryngeal mask airway (LMA), which is used in difficult airway maintenance conditions during emergencies, is rarely used in prolonged surgery despite its advantages over endotracheal tube (ETT). In this study, we conducted a comparative analysis of intraoperative gas exchanges between second-generation LMA and ETT during prolonged laparoscopic abdominal surgery. Prolonged surgery was defined as a surgery lasting more than 2 h. In total, 394 patients who underwent laparoscopic liver resection via either second-generation LMA or ETT were retrospectively analysed. The following parameters were compared between the two groups of patients: end-tidal pressure of carbon dioxide (ETCO2), tidal volume (TV), respiratory rate (RR), peak inspiratory pressure (PIP), arterial partial pressure of carbon dioxide (PaCO2), pH and ratio of arterial partial pressure of oxygen to fractional inspired oxygen (PFR) during surgery. In addition, the incidence of postoperative pulmonary complications (PPCs), including pulmonary aspiration, was compared. The values of ETCO2, TV, RR and PIP during pneumoperitoneum were comparable between the two groups. Although PaCO2 at 2 h after induction was higher in patients in the LMA group (40.5 vs. 38.5 mmHg, P < 0.001), the pH and PFR values of the two groups were comparable. The incidence of PPC was similar. During prolonged laparoscopic abdominal surgery, second-generation LMA facilitates adequate intraoperative gas exchange and may serve as an alternative to ETT.

Tidal volume and stroke volume changes caused by respiratory events during sleep and their relationship with OSA severity: a pilot study.

Breath-by-breath tidal volume (TV) and beat-by-beat stroke volume (SV) were continuously measured in patients with OSA undergoing polysomnography (PSG). The objectives were to (1) determine the changes in TV/SV in response to respiratory events and (2) assess the relationship between these changes and the disease severity. From the PSG data of nine patients withOSA, six different types of respiratory events were identified, i.e., flow limitation (FL), respiratory effort related arousal (RERA), hypopnea with arousal only (Ha), hypopnea with desaturation only (Hd), hypopnea with arousal and desaturation (Had), and apnea. The measured TV and SV values during and after each respiratory event were compared with the pre-event baseline values. The mean TV/SV reductions during all hypopneas and apneas were 38.1%/4.2% and 70.5%/8.8%, respectively. Among three different hypopnea types, the reductions in TV during Hd and Had were significantly greater than those during Ha. The TV reductions during Ha and FL were similar. After RERA, Ha, Had, and apnea, there was an overshoot in TV and SV values, whereas there was no overshoot after FL and Hd. During RERA, there was no reduction in TV/SV. The changes in TV during and after each type of respiratory event were significantly different in most cases. The changes in SV between hypopnea and apnea were different with statistical significance. The AHI does not properly account for the ventilation losses caused by respiratory events. Thus, TV measurements might be useful in the future in assessing the OSA severity in conjunction with the AHI.

Day-to-Day Variability of Parameters Recorded by Home Noninvasive Positive Pressure Ventilation for Detection of Severe Acute Exacerbations in COPD.

BackgroundHome noninvasive positive pressure ventilation (NPPV) can be considered not only as an evidence-based treatment for stable hypercapnic chronic obstructive pulmonary disease (COPD) patients, but also as a predictor for detecting severe acute exacerbations of chronic obstructive pulmonary disease (AECOPD).MethodsIn this retrospective observational study, we collected clinical exacerbations information and daily NPPV-related data in a cohort of COPD patients with home NPPV for 6 months. Daily changes in NPPV-related parameters’ variability prior to AECOPD were examined using two-way repeated measures ANOVA and individual abnormal values (>75th or <25th percentile of individual baseline parameters) were calculated during 7-day pre-AECOPD period. Multivariate logistic regression was used to identify the independent risk factors associated with AECOPD that then were incorporated into the nomogram.ResultsBetween January 1, 2018, and January 1, 2020, a total of 102 patients were included and 31 (30.4%) participants experienced hospitalization (AECOPD group) within 6 months. Respiratory rate changed significantly from baseline at 1, 2 or 3 days prior to admission (p<0.001, respectively) in the AECOPD group. The number of days with abnormal values of daily usage, leaks, or tidal volume during the 7-day pre-AECOPD period in the AECOPD group was higher than in the stable group (p<0.001, respectively). On multivariate analysis, 7-day mean respiratory rate (OR 1.756, 95% CI 1.249–2.469), abnormal values of daily use (OR 1.918, 95% CI 1.253–2.934) and tidal volume (OR 2.081, 95% CI 1.380–3.140) within 7 days were independently associated with the risk of AECOPD. Incorporating these factors, the nomogram achieved good concordance indexes of 0.962.ConclusionSeven-day mean respiratory rate, abnormal values of daily usage, leaks, and tidal volume within the 7-day pre-AECOPD period may be biomarkers for detection of AECOPD.

Temporal changes in the epidemiology, management, and outcome from acute respiratory distress syndrome in European intensive care units: a comparison of two large cohorts

BackgroundMortality rates for patients with ARDS remain high. We assessed temporal changes in the epidemiology and management of ARDS patients requiring invasive mechanical ventilation in European ICUs. We also investigated the association between ventilatory settings and outcome in these patients.MethodsThis was a post hoc analysis of two cohorts of adult ICU patients admitted between May 1–15, 2002 (SOAP study, n = 3147), and May 8–18, 2012 (ICON audit, n = 4601 admitted to ICUs in the same 24 countries as the SOAP study). ARDS was defined retrospectively using the Berlin definitions. Values of tidal volume, PEEP, plateau pressure, and FiO2 corresponding to the most abnormal value of arterial PO2 were recorded prospectively every 24 h. In both studies, patients were followed for outcome until death, hospital discharge or for 60 days.ResultsThe frequency of ARDS requiring mechanical ventilation during the ICU stay was similar in SOAP and ICON (327[10.4%] vs. 494[10.7%], p = 0.793). The diagnosis of ARDS was established at a median of 3 (IQ: 1–7) days after admission in SOAP and 2 (1–6) days in ICON. Within 24 h of diagnosis, ARDS was mild in 244 (29.7%), moderate in 388 (47.3%), and severe in 189 (23.0%) patients. In patients with ARDS, tidal volumes were lower in the later (ICON) than in the earlier (SOAP) cohort. Plateau and driving pressures were also lower in ICON than in SOAP. ICU (134[41.1%] vs 179[36.9%]) and hospital (151[46.2%] vs 212[44.4%]) mortality rates in patients with ARDS were similar in SOAP and ICON. High plateau pressure (> 29 cmH2O) and driving pressure (> 14 cmH2O) on the first day of mechanical ventilation but not tidal volume (> 8 ml/kg predicted body weight [PBW]) were independently associated with a higher risk of in-hospital death.ConclusionThe frequency of and outcome from ARDS remained relatively stable between 2002 and 2012. Plateau pressure > 29 cmH2O and driving pressure > 14 cmH2O on the first day of mechanical ventilation but not tidal volume > 8 ml/kg PBW were independently associated with a higher risk of death. These data highlight the continued burden of ARDS and provide hypothesis-generating data for the design of future studies.

ЕФЕКТИВНІСТЬ ЗАСТОСУВАННЯ ПЛАВАННЯ ДЛЯ ВІДНОВЛЕННЯ ФУНКЦІОНАЛЬНОГО СТАНУ КАРДІОРЕСПІРАТОРНОЇ СИСТЕМИ ПІСЛЯ ПЕРЕНЕСЕНИХ ЗАПАЛЕНЬ ЛЕГЕНЬ

Мета. Встановити вплив занять плаванням на відновлення функціональних резервів кардіореспіраторної системи після перенесених запальних захворювань легень. Методи. У дослідженні взяли участь 50 осіб (12 жінок і 38 чоловіків, середній вік 42,01±1,29 років) після завершення стаціонарного лікування з приводу запальних захворювань легень в пульмонологічному відділенні Івано-Франківського обласного фтизіопульмонологічного центру. За погодженням з лікуючими лікарями вони були скеровані у санаторії “Алмаз” і “Кристал (м. Трускавець) де основним групам (ОГ) у кількості 25 осіб чоловічої і 6 жіночої статі було створено умови для щоденних занять плаванням протягом 18 днів. Тривалість кожного заняття складала 45 хвилин, а обсяг фізичного навантаження – 400–800 м при ЧСС 120-140 уд/хв. Контрольні групи протягом перебування в санаторії плавання не використовували. Для оцінки основних показників функції зовнішнього дихання використовувався комп’ютерний спірометр Mіcrospіro HІ-501. Визначення загальної фізичної працездатності здійснювали за допомогою проби Джеймса. Обстеження здійснювали двічі (до початку і після завершення циклу занять плаванням). Результати. Порівняльний аналіз змін середніх значень дихального об’єму і життєвої ємності легень контрольної й основної групи чоловіків свідчить про те, що в основній групі ці показники зовнішнього дихання перевищують дані групи контролю на 10,9% і 4,0% відповідно (р&lt;0,05). Аналіз засвідчує, Щодо жінок, то величини дихального об’єму та життєвої ємності легень основної групи наприкінці занять зросли у порівнянні з групою контролю на 5,0% і 12,4% відповідно. Вірогідні зміни виявлені також і в показниках хвилинного об’ємудихання, форсованого об’єму дихання та пікової швидкості видиху як у чоловіків, так і в жінок. Висновок. Застосування плавання у відновному періоді осіб, які перенесли запальні захворювання дихальної системи забезпечує нормалізацію функціонування як дихальної, так і серцево-судинної системи, що опосередковано свідчить про нормалізацію механізмів нейрогуморальної регуляції функцій організму.Ключові слова: плавання, запальні захворювання легень, функціональний стан.

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.

Comparing two airway management strategies for moderately sedated patients undergoing awake craniotomy: A single-blinded randomized controlled trial.

In the monitored anesthesia care (MAC) setting for awake craniotomy (AC), maintaining airway patency in sedated patients remains challenging. This randomized controlled trial aimed to compare the validity of the below-epiglottis transnasal tube insertion (the tip of the tube placed between the epiglottis and vocal cords) and the nasopharyngeal airway (simulated by the above-epiglottis transnasal tube with the tip of the tube placed between the epiglottis and the free edge of the soft palate) with respect to maintaining upper airway patency for moderately sedated patients undergoing AC. Sixty patients scheduled for elective AC were randomized to receive below-epiglottis (n=30) or above-epiglottis (n=30) transnasal tube insertion before surgery. Moderate sedation was maintained in the pre- and post-awake phases. The primary outcome was the upper airway obstruction (UAO) remission rate (relieved obstructions after tube insertion/the total number of obstructions before tube insertion). The UAO remission rate was higher in the below-epiglottis group [100% (12/12) vs 45% (5/11); P=.005]. The tidal volume values monitored through the tube were greater in the below-epiglottis group during the pre-awake phase (P<.001). End-tidal carbon dioxide (EtCO2 ) monitored through the tube was higher in the below-epiglottis group at bone flap removal (P<.001). During the awake phase, patients' ability to speak was not impeded. No patient had serious complications related to the tube. The below-epiglottis tube insertion is a more effective method to maintain upper airway patency than the nasopharyngeal airway for moderately sedated patients undergoing AC.

Evaluating Tidal Volume Delivered by a Self-Inflating Bag Depending on the Compression Method.

A self-inflating bag (SIB) is an essential device for pulmonary resuscitation in emergencies. However, it is difficult for a rescuer to accurately predict a tidal volume (TV) delivered by a SIB to a patient. The objective of this study was to evaluate TV values delivered by a SIB with various compression methods. A total of 33 participants were enrolled in this study. Anterior, middle, and posterior points were marked on the surface of the SIB to guide participants to place their fingers. This was connected to a gas-flow analyzer and a test lung to measure the TV. Participants were asked to squeeze the SIB with one-handed and two-handed compression at anterior, middle, and posterior points. The TV was the largest when the bag was squeezed with two-handed compression at the middle points (578 ± 21 mL). It was the smallest when the bag was squeezed with one-handed compression at the anterior point (311 ± 15 mL). Except that the TV with one-handed compression at the middle point and the TV with two-handed compression at the posterior points were similar, all other TV values were significantly different from each other (all p ＜ 0.001). The TV delivered by a SIB could differ greatly depending on the compression points and whether one or two hands are used. Therefore, a rescuer should choose an appropriate compression method considering patient's physical characteristics and medical conditions.

Effectiveness of a Real-Time Ventilation Feedback Device for Guiding Adequate Minute Ventilation: A Manikin Simulation Study.

Background and objectives: It is often challenging even for skilled rescuers to provide adequate positive pressure ventilation consistently. This study aimed to investigate the effectiveness of a newly developed real-time ventilation feedback device (RTVFD) that estimates tidal volume (TV) and ventilation interval (VI) in real time. Materials and methods: We conducted a randomised, crossover, manikin simulation study. A total of 26 medical providers were randomly assigned to the RTVFD-assisted ventilation (RAV) first group (n = 13) and the non-assisted ventilation (NV) first group (n = 13). Participants provided ventilation using adult and paediatric bag valves (BVs) for 2 min each. After a washout period, the simulation was repeated by exchanging the participants’ groups. Results: The primary outcome was optimal TV in the RAV and NV groups using adult and paediatric BVs. A secondary outcome was optimal VI in the RAV and NV groups using adult and paediatric BVs. The proportions of optimal TV values were higher for the RAVs when using both adult and paediatric BVs (adult BV: 47.29% vs. 18.46%, p < 0.001; paediatric BV: 89.51% vs. 72.66%, p < 0.001) than for the NVs. The proportions of optimal VI were significantly higher in RAVs when using both adult and paediatric BVs than that in NVs (adult BV: 95.64% vs. 50.20%, p < 0.001; paediatric BV: 95.83% vs. 57.14%, p < 0.001). Additionally, we found that with paediatric BVs, the simulation had a higher OR for both optimal TV (13.26; 95% CI, 9.96–17.65; p < 0.001) and VI (1.32; 1.08–1.62, p = 0.007), regardless of RTVFD use. Conclusion: Real-time feedback using RTVFD significantly improves the TV and VI in both adult and paediatric BVs in a manikin simulation study.

A study on cuff pressure of laryngeal mask for airway management of child patients undergoing operation

To investigate the cuff pressure of laryngeal mask for airway management of child patients undergoing operations. One hundred thirty-eight children who underwent general anesthesia in our hospital from June 2014 to May 2017 were enrolled, 46 children from June 2014 to September 2014 were selected as group A (20 cmH2O pressure group). 46 patients from October 2014 to January 2015 were selected as group B (40 cmH2O pressure group), and 46 patients from February 2015 to May 2015 were selected as group C (60 cmH2O pressure group). The pressure of all child patients was adjusted to the appointed pressure by using cuff pressure gauge. The operation situation, insertion of laryngeal mask, oropharyngeal leakage pressure(OLP), airway peak pressure(Ppeak), difference value of exhaled tidal volume(∆VT) and adverse reactions of the child patients from three groups were compared. The differences in anesthesia time, recovery time, insertion time of laryngeal mask, removal time of laryngeal mask, operation duration and Ppeak showed no statistical significance (P>0.05); the successful rates of first insertion of laryngeal mask of group A, group B and group C were 89.13%, 100.00% and 93.47%, respectively. The OLPs of Group B and C were higher than that of Group A, and that of Group C was higher than Group B. ∆VT of Group B and C were lower than that of Group A, and that of Group B was lower than that of Group C. The total incidence rates of adverse reactions of three groups were 39.11%, 15.21% and 28.23%, respectively. The optimum cuff pressure of laryngeal mask is 40 cmH2O for child patients during the airway management, which can effectively increase OLP, decrease ∆VT and incidence rate of adverse reactions, worthy of further recommendation and application in clinical practices.

Tidal volumes at birth as predictor for adverse outcome in congenital diaphragmatic hernia

ObjectiveTo assess the predictive value of tidal volume (Vt) of spontaneous breaths at birth in infants with congenital diaphragmatic hernia (CDH).DesignProspective study.SettingTertiary neonatal intensive care unit.PatientsThirty infants with antenatally diagnosed...

Utility of a smartphone based system (cvrphone) to accurately determine apneic events from electrocardiographic signals.

BackgroundSleep disordered breathing manifested as sleep apnea (SA) is prevalent in the general population, and while it is associated with increased morbidity and mortality risk in some patient populations, it remains under-diagnosed. The objective of this study was to assess the accuracy of respiration-rate (RR) and tidal-volume (TV) estimation algorithms, from body-surface ECG signals, using a smartphone based ambulatory respiration monitoring system (cvrPhone).MethodsTwelve lead ECG signals were collected using the cvrPhone from anesthetized and mechanically ventilated swine (n = 9). During ECG data acquisition, the mechanical ventilator tidal-volume (TV) was varied from 250 to 0 to 750 to 0 to 500 to 0 to 750 ml at respiratory rates (RR) of 6 and 14 breaths/min, respectively, and the RR and TV values were estimated from the ECG signals using custom algorithms.ResultsTV estimations from any two different TV settings showed statistically significant difference (p < 0.01) regardless of the RR. RRs were estimated to be 6.1±1.1 and 14.0±0.2 breaths/min at 6 and 14 breaths/min, respectively (when 250, 500 and 750 ml TV settings were combined). During apnea, the estimated TV and RR values were 11.7±54.9 ml and 0.0±3.5 breaths/min, which were significantly different (p<0.05) than TV and RR values during non-apnea breathing. In addition, the time delay from the apnea onset to the first apnea detection was 8.6±6.7 and 7.0±3.2 seconds for TV and RR respectively.ConclusionsWe have demonstrated that apnea can reliably be detected using ECG-derived RR and TV algorithms. These results support the concept that our algorithms can be utilized to detect SA in conjunction with ECG monitoring.

The Effect of Sevoflurane and Dexmedetomidine on Pulmonary Mechanics in ICU Patients.

In intensive care unit (ICU) patients, intravenous (iv) and volatile agents are used for sedation. The aim of the present study was to investigate the effects of dexmedetomidine and sevoflurane on pulmonary mechanics in ICU patients with pulmonary disorders. After approval of the ethical committee and informed consent between the ages of 18-65 years were obtained, 30 patients with an American Society of Anesthesiologist status I-III, who were mechanically ventilated, who had pulmonary disorders and who needed sedation were included in the study. Exclusion criteria were severe hepatic, pulmonary and renal failures; pregnancy; convulsion and/or seizure history; haemodynamic instability and no indication for sedation. Patients were divided into two groups by randomised numbers generated by a computer. For sedation, 0.5%-1% sevoflurane (4-10 mL h-1) was used by an Anaesthetic Conserving Device in Group S (n=15), and iv dexmedetomidine infusion (1 μg-1 kg-1 10 min-1 loading and 0.2-0.7 μg-1 kg-1 h-1 maintenance) was performed in Group D (n=15). Arterial blood gas analysis, airway resistance, positive end-expiratory pressure (PEEP), frequency, tidal volume (TV), peak airway pressure (Ppeak), static pulmonary compliance and end-tidal CO2 values were recorded at baseline, 1, 3, 6, 9, 12 and 24 h. Demographic data, airway resistance, PEEP, frequency, TV, Ppeak and static pulmonary compliance values were similar between the groups. PaCO2 and end-tidal CO2 values were higher in Group S than in Group D. Sedation and patient comfort scores were similar between the two groups. Both sevoflurane and dexmedetomidine are suitable sedative agents in ICU patients with pulmonary diseases.

Mechanical-ventilatory responses to peak and ventilation-matched upper- versus lower-body exercise in normal subjects.

New Findings What is the central question of this study? To what extent are the mechanical‐ventilatory responses to upper‐body exercise influenced by task‐specific locomotor mechanics? What is the main finding and its importance? When compared with lower‐body exercise performed at similar ventilations, upper‐body exercise was characterized by tidal volume constraint, dynamic lung hyperinflation and an increased propensity towards neuromechanical uncoupling of the respiratory system. Importantly, these responses were independent of respiratory dysfunction and flow limitation. Thus, the mechanical ventilatory responses to upper‐body exercise are attributable, in part, to task‐specific locomotor mechanics (i.e. non‐respiratory loading of the thorax). The aim of this study was to determine the extent to which the mechanical ventilatory responses to upper‐body exercise are influenced by task‐specific locomotor mechanics. Eight healthy men (mean ± SD: age, 24 ± 5 years; mass, 74 ± 11 kg; and stature, 1.79 ± 0.07 m) completed two maximal exercise tests, on separate days, comprising 4 min stepwise increments of 15 W during upper‐body exercise (arm‐cranking) or 30 W during lower‐body exercise (leg‐cycling). The tests were repeated at work rates calculated to elicit 20, 40, 60, 80 and 100% of the peak ventilation achieved during arm‐cranking (V˙E, UBE ). Exercise measures included pulmonary ventilation and gas exchange, oesophageal pressure‐derived indices of respiratory mechanics, operating lung volumes and expiratory flow limitation. Subjects exhibited normal resting pulmonary function. Arm‐crank exercise elicited significantly lower peak values for work rate, O2 uptake, CO2 output, minute ventilation and tidal volume (p < 0.05). At matched ventilations, arm‐crank exercise restricted tidal volume expansion relative to leg‐cycling exercise at 60% V˙E, UBE (1.74 ± 0.61 versus 2.27 ± 0.68 l, p < 0.001), 80% V˙E, UBE (2.07 ± 0.70 versus 2.52 ± 0.67 l, p < 0.001) and 100% V˙E, UBE (1.97 ± 0.85 versus 2.55 ± 0.72 l, p = 0.002). Despite minimal evidence of expiratory flow limitation, expiratory reserve volume was significantly higher during arm‐cranking versus leg‐cycling exercise at 100% V˙E, UBE (39 ± 8 versus 29 ± 8% of vital capacity, p = 0.002). At any given ventilation, arm‐cranking elicited greater inspiratory effort (oesophageal pressure) relative to thoracic displacement (tidal volume). Arm‐cranking exercise is sufficient to provoke respiratory mechanical derangements (restricted tidal volume expansion, dynamic hyperinflation and neuromechanical uncoupling) in subjects with normal pulmonary function and expiratory flow reserve. These responses are likely to be attributable to task‐specific locomotor mechanics (i.e. non‐respiratory loading of the thorax).

Changed dynamic ventilation parameters as a result of a breathing exercise intervention program.

The performance of the respiratory system during the exercise is limiting the final performance in endurance disciplines. The quality of breathing is linked to endurance performance, subject´s training state, intensity and duration of the physical load, the implementation of which, thus the economy of breathing, is possible to influence through a targeted breathing exercise. The aim of this study is to evaluate the effect of breathing intervention exercises on the effectiveness of breathing by monitoring value of tidal volume (VT) and breathing frequency (BF) during an endurance type load in adolescent endurance runners. Thirty-seven 37 adolescent endurance runners were enrolled in this study. The girls were 16.79±1.51 years old, the boys were 16.5±1.8 years old. They are involved in endurance training for at least one year. Twenty-one probands took part in the intervention scheme; sixteen probands formed the control group. The study investigated the effect of two months and four months of breathing exercise intervention on tidal volume VT and BF. The probands carried out breathing exercises, which took an average of 13.1±3.7 minutes per day over the first two months, and an average of 11.1±3.9 minutes per day over the next two months. The breathing economy was significantly changed as a result of respiratory exercise intervention. Already after 2 months of intervention there was a significant decrease of BF (by 5.92%) and a significant increase of VT (by 4.44%). After another 2 months, the changes were even more pronounced. In the 4 months of the intervention, the BF decreased by 11.47% and the VT increased by 10.96% in comparison to the original state. In the control group, there were no significant changes. It was confirmed that the two-month breathing exercise intervention focused on the activation of the diaphragm is sufficient and resulted in significant changes of in VT and BF.

Influence of dexamethasone and surfactant in the vitality and lung function of preterm lambs born by cesarean section

ABSTRACT The aim of this study was to assess the vitality and lung function of preterm lambs. Twenty seven preterm lambs were divided in four groups. Group I (n=6) preterm lambs/ control; group II (n=9) lambs born to mothers that were treated with dexamethasone antepartum; group III (n=6) lambs treated with surfactant; and group IV (n=6) lambs treated with surfactant and born to mothers that were treated with dexamethasone antepartum. The APGAR score was performed after birth (T0) and 15 minutes later (T1/4) to assess vitality. The vital signs, blood gas analysis, spirometry and capnometry were assessed immediately after birth and continued until 48 hours. Chest radiographs were performed at T0, T24 and T48. Significant rectal temperature interactions occurred at T1 and T6 depending on the type of treatment used. All animals showed low pH values, which were associated with high pCO2 values and HCO3 -values that increased over time from immediately after birth to two days of age. Higher tidal volume values were observed at T1/4, T1 and T24 when the animals were not treated with surfactant. Capnometry showed significant interactions between treatments at T0. Premature animals showed low vitality and impaired pulmonary function.

Driving pressure during proportional assist ventilation: an observational study

BackgroundDuring passive mechanical ventilation, the driving pressure of the respiratory system is an important mediator of ventilator-induced lung injury. Monitoring of driving pressure during assisted ventilation, similar to controlled ventilation, could be a tool to identify patients at risk of ventilator-induced lung injury. The aim of this study was to describe driving pressure over time and to identify whether and when high driving pressure occurs in critically ill patients during assisted ventilation.MethodsSixty-two patients fulfilling criteria for assisted ventilation were prospectively studied. Patients were included when the treating physician selected proportional assist ventilation (PAV+), a mode that estimates respiratory system compliance. In these patients, continuous recordings of all ventilator parameters were obtained for up to 72 h. Driving pressure was calculated as tidal volume-to-respiratory system compliance ratio. The distribution of driving pressure and tidal volume values over time was examined, and periods of sustained high driving pressure (≥ 15 cmH2O) and of stable compliance were identified and analyzed.ResultsThe analysis included 3200 h of ventilation, consisting of 8.8 million samples. For most (95%) of the time, driving pressure was < 15 cmH2O and tidal volume < 11 mL/kg (of ideal body weight). In most patients, high driving pressure was observed for short periods of time (median 2.5 min). Prolonged periods of high driving pressure were observed in five patients (8%). During the 661 periods of stable compliance, high driving pressure combined with a tidal volume ≥ 8 mL/kg was observed only in 11 cases (1.6%) pertaining to four patients. High driving pressure occurred almost exclusively when respiratory system compliance was low, and compliance above 30 mL/cmH2O excluded the presence of high driving pressure with 90% sensitivity and specificity.ConclusionsIn critically ill patients fulfilling criteria for assisted ventilation, and ventilated in PAV+ mode, sustained high driving pressure occurred in a small, yet not negligible number of patients. The presence of sustained high driving pressure was not associated with high tidal volume, but occurred almost exclusively when compliance was below 30 mL/cmH2O.

Application of multiple-path particle dosimetry model for quantifying age specified deposition of particulate matter in human airway

Particulate matter (PM) is crucial among six criteria air pollutants, and it is frequently associated with human morbidity and mortality. According to the aerodynamic diameter, PM is classified as coarse (PM10) and fine (PM2.5). PM with these smaller sizes can easily enter and get deposited in the human airways. This deposited PM fraction commences the development of respiratory diseases such as asthma, chronic obstructive pulmonary disease, and even cancer. Thus, the quantification of PM deposition and its clearance in the human airway are essential for evaluating health risks. This study aims to investigate the size-segregated PM (PM10, PM2.5, and PM1) deposition in human lungs. Size-segregated PM is collected using the Grimm portable environmental dust monitor during winter season near an arterial road located in Chennai city of Tamil Nadu state, India. Multiple-Path Particle Dosimetry (MPPD) Model version 3.04 is utilized for quantifying PM deposition. In MPPD, airway structures of infants (3 and 28 months), children (3, 8, 9 and 14 years) and adults (18 and 21 years) are considered for the study. The values of PM concentration, body orientation, breathing scenario, tidal volume, pause fraction, inspiration fraction, and breathing frequency are specified in the MPPD for quantifying PM depositions. Results showed that 8-year children and 28 months infant groups are recorded with maximum and minimum size-segregated PM deposition respectively. The coarse particles (PM10) are primarily deposited in the head (55–95%) and tracheobronchial (3–44%) regions whereas fine particles (PM2.5 and PM1) depositions are observed maximum in the head (36–63%) and pulmonary (28.2–52.7%) regions. Except for the adult age group, PM2.5 has the maximum deposition percentage in tracheobronchial and pulmonary regions. In the case of lobar depositions, lower lobes receive maximum deposition (66.4%) than the upper (27.2%) and middle lobes (6.4%). PM2.5 dominated the deposition in all five lobes of infant, children, and adults. The clearance rate of deposited PM is high in the tracheobronchial region whereas it is low in the pulmonary region. This study also concludes that PM2.5 is the important size fraction in lung deposition. Further, the study results can be used for human health risk assessments such as oxidative potential and toxicity of deposited PM.