Peak Inspiratory Flow Research Articles

Why NIV setting definitions may be tricky: trigger sensitivity

Noninvasive ventilation (NIV) is widely use in children. The spontaneous/timed (S/T) mode is the most common used mode for home NIV. Different devices are available, and the manufacturers are free to name the modes and define the settings, with no regulation. In particular, the definitions of the trigger sensitivities still differ between manufacturers and/or devices. The inspiratory trigger (TgI) sensitivity may be set according to a numerical or word-rating scale, while the expiratory trigger (TgE) sensitivity may be set as a percentage of the peak inspiratory flow, or using a numerical or word rating scale which correspond to specific predefined percentages of inspiratory flow. Moreover, the TgE sensitivity may be set according to the peak inspiratory flow or to the diminution of peak inspiratory flow, which may be very confusing. Patient-ventilator asynchrony (PVA) may be due to an inadequate comprehension of the settings by the user, which is challenging. We report here the cases of four children and adolescents with an incorrect setting of the TgI and/or TgE, leading to PVA. This pleads for a harmonization of the definitions of the settings, and in particular of the trigger sensitivities. In the meanwhile, NIV professionals should be aware of the different definitions to avoid setting errors leading to PVA.

Accuracy of Real-Time Data Provided by Mechanical Insufflation-Exsufflation Devices.

Mechanical insufflation-exsufflation (MI-E) is crucial to assist patients with impaired cough, especially those with neuromuscular diseases. Despite recent advancements that enable real-time display of peak expiratory flow (PEF) and inspiratory volume, accurately monitoring these parameters with MI-E devices during treatment can still present challenges. A bench study that used a mechanical lung connected to 3 MI-E devices (EOVE-70; E-70 and Comfort Cough II) was conducted to evaluate PEF and inspiratory volume monitoring accuracy. Two clinical conditions were tested, low and normal compliance, with 6 different MI-E settings tested: +20/-20, +30/-30, +40/-40, +40/-50, +40/-60, and +40/-70 cm H2O. PEF (L/min) and inspiratory volume (mL) displayed on the screen were recorded cycle by cycle, while a pneumotachograph connected to the mechanical lung was used to measure the actual PEF and inspiratory volume for data comparison. Flow bias was assessed by calculating the difference (PEF - peak inspiratory flow) and ratio (PEF to peak inspiratory flow) between flows. All devices systematically underestimated PEF, with device A showing the smallest estimation error (-7.4 [-10.1; -6] %). Devices B and C exhibited larger errors (-26.5 [-29.2; -25.6] and (-29.9 [-30.7; -28.7] %, respectively). All the devices underestimated inspiratory volume, with device B showing the smallest estimation error (-15.1 [-21.2; -12.3] %). Device A exhibited a significantly larger error (-26.9 [-30.3; -24.8] %). The error from device C (-17.7 [-34.5; -13.8] %) was not statistically different from device B. Device type, high pressure settings (> +40/-40 cm H2O), and a lung model compliance of 60 mL/cm H2O were the main contributors to error in estimating PEF and inspiratory volume. Finally, we observed differences of PEF-to-peak inspiratory flow ratio and PEF minus peak inspiratory flow differences achieved. Our study highlighted consistent underestimation of PEF and inspiratory volume across MI-E devices. Improving device monitoring is essential for guiding MI-E therapy and ensuring patient safety.

Allergic rhinitis: a brief overview of the etiopathogenesis and rehabilitation of patients

The article presents a brief overview of modern literature sources concerning the prevalence, etiopathogenetic approaches in the diagnosis and treatment of allergic rhinitis. The relevance of the problem under consideration is due to the high prevalence of this pathology, the variety of etiopathogenetic mechanisms and the variability of classifications. One of the most popular classifications is seasonal. When studying pathogenetic mechanisms, the following patterns were revealed: the nasal mucosa is the main air conditioner of the respiratory tract and the first line of defense against infectious agents transmitted by airborne droplets. These roles require maintaining and restoring epithelial integrity and the ability to initiate immune responses. When conditions or factors are present that compromise the integrity of the mucosa, the epithelium releases alarmins and other molecular patterns associated with damage that trigger repair mechanisms but can also cause protective inflammation. In allergic rhinitis, the same mechanisms can activate the development of the disease. Many authors consider various diagnostic methods for allergic rhinitis. Such as a detailed and competent collection of complaints and anamnesis, including family history, physical examination, endoscopic examination of the nasal cavity, rhinomanometry, skin prick tests, radiological studies, including computed tomography of the paranasal sinuses, intradermal tests, study of total and specific immunoglobulins E in blood serum, basophil activation test, nasal provocation test, nasal cytology and biopsy histology, acoustic rhinometry, nasal inspiratory peak flow testing, and nitric oxide measurements are used. Attention is also paid to laboratory and instrumental methods for the differential diagnosis of rhinitis of pseudoallergic origin; the following methods are used: ultrasound diagnostics of the hepatobiliary system, biochemical blood test, and immunological studies. Treatment of patients with allergic rhinitis requires an integrated and interdisciplinary approach and, of course, requires differential and personalized methods taking into account etiopathogenetic mechanisms.

Monitoring and modulating respiratory drive in mechanically ventilated patients.

Respiratory drive is frequently deranged in the ICU, being associated with adverse clinical outcomes. Monitoring and modulating respiratory drive to prevent potentially injurious consequences merits attention. This review gives a general overview of the available monitoring tools and interventions to modulate drive. Airway occlusion pressure (P0.1) is an excellent measure of drive and is displayed on ventilators. Respiratory drive can also be estimated based on the electrical activity of respiratory muscles and measures of respiratory effort; however, high respiratory drive might be present in the context of low effort with neuromuscular weakness. Modulating a deranged drive requires a multifaceted intervention, prioritizing treatment of the underlying cause and adjusting ventilator settings for comfort. Additional tools include changes in PEEP, peak inspiratory flow, fraction of inspired oxygen, and sweep gas flow (in patients receiving extracorporeal life-support). Sedatives and opioids have differential effects on drive according to drug category. Monitoring response to any intervention is warranted and modulating drive should not preclude readiness to wean assessment or delay ventilation liberation. Monitoring and modulating respiratory drive are feasible based on physiological principles presented in this review. However, evidence arising from clinical trials will help determine precise thresholds and optimal interventions.

Inhaler personalisation based on peak inspiratory flow (PIF) among dry powder inhaler users: a pilot randomised control trial (RCT) in COPD.

Dry powder inhalers (DPIs) are commonly used among patients with Chronic Obstructive Pulmonary Disease (COPD). These inhalers are breath-actuated, and require patients to generate sufficient peak inspiratory flow (PIF) to disaggregate the drug powder into respirable fine particles and deliver it to the lower airway tracts. Inhaler personalisation based on PIF among DPI users has not been studied in Malaysia, thus we conducted the present pilot study to determine the feasibility of conducting such research among COPD patients. This was an open-label pilot randomised control trial, conducted from June 2021-January 2022 at the respiratory clinic of Hospital Canselor Tuanku Muhriz, Universiti Kebangsaan Malaysia. Measurement of PIF was performed with In-Check DIAL G16 among adult COPD patients treated with DPI and had suboptimal PIF. Eligible subjects were randomised using block randomisation into two groups, either the interventional group or the control group. Twenty-two COPD patients fulfilled the study criteria and were randomised to intervention (n = 11) and control (n = 11) groups. For the interventional group, there were statistically significant improvements between baseline and at 12 weeks for both FEV1 and CAT scores. The mean (% predicted) FEV1 were 54.6 ± 20.4% and 56.6 ± 19.8% (p = 0.026), pre-and post-intervention. The mean CAT score at baseline was 24.4 ± 5.8 and reduced to 19.6 ± 4.4 at 12 weeks (p = 0.012). For the control group, the mean (% predicted) FEV1 at baseline was 58.0 ± 21.9% and 56.5 ± 20.7% at 12 weeks, with no statistical significance difference (p = 0.143). However, there was a statistically significant difference in CAT scores at baseline and 12 weeks, with a mean of 26.5 ± 6.1 and 23.3 ± 5.6, respectively (p = 0.010). The findings from the present pilot RCT highlighted that inhaler personalisation based on PIF among COPD patients was feasible and practical.

Peak Inspiratory Flow and Inhaler Prescription Strategies in a Specialized COPD Clinical Program: A Real-World Observational Study

BackgroundCOPD inhaler regimens should be appropriate for the patient’s peak inspiratory flow (PIF) and should ideally consist of single or similar device(s). Research QuestionsIn a subspecialized COPD clinic: 1What is the prevalence of patients with suboptimal PIF and with inappropriate device(s) for measured PIF? 2Are there patient-related risk factors associated with suboptimal PIF? 3What is the prevalence of patients with non-single inhaler therapy (SIT)/non-similar devices? 4Does point-of-care PIF affect clinical decision-making? Study Design and MethodsIn this single-center real-world observational study, PIF was measured systematically at every outpatient visit in a subspecialized COPD clinic and point-of-care results were provided to the clinician. Co-primary outcomes were the prevalence of outpatients with suboptimal PIF and with inappropriate devices for measured PIF. Secondary outcomes were patient-related risk factors associated with suboptimal PIF, the prevalence of non-SIT/non-similar devices, the prevalence of regimens consisting of either inappropriate device(s) for measured PIF and/or non-SIT/non-similar devices, and the effect of point-of-care PIF on clinical decision-making. ResultsSuboptimal PIF was identified in 45 of 161 participants (28%) and inappropriate device(s) for measured PIF were identified in 18 (11.2%) participants. Significant associations were observed between suboptimal PIF and age (1.09 [1.04,1.15]), female sex (10.30 [4.45,27.10]), height (0.92 [0.88,0.96]), BMI (0.90 [0.84,0.96]) and FEV1 (0.09 [0.03,0.26]). Following adjustment for age and sex, the association between suboptimal PIF and BMI, but not height, remained significant. Non-SIT and/or non-similar devices were identified in 50 (31.1%) participants. Regimens consisting of either inappropriate device(s) for measured PIF and/or non-SIT/non-similar devices were observed in fifty-nine (36.6%) participants. Inhaler prescription changes were observed in this latter group (3.39 [1.76,6.64]), as well as in patients with suboptimal PIF already on SIT/similar regimens (2.93 [1.07,7.92]). InterpretationSuboptimal PIF and inappropriate devices for measured PIF are highly prevalent in outpatients from a subspecialized COPD clinic. Female sex, reduced FEV1 and low BMI are important, readily identifiable risk factors for suboptimal PIF and point-of-care PIF can inform clinical decision-making.

Evaluation of a new hyperbaric oxygen ventilator during pressure-controlled ventilation.

The stability of a new hyperbaric ventilator (Shangrila590, Beijing Aeonmed Company, Beijing, China) at different clinically relevant pressures in a hyperbaric chamber during pressure-controlled ventilation (PCV) was investigated. The ventilator was connected to a test lung in the multiplace hyperbaric chamber. The inspiratory pressure (PI) of the ventilator was set to 1.0, 1.5, 2.0, 2.5 and 3.0 kPa (approximately 10, 15, 20, 25 and 30 cmH₂O). The compliance and resistance of the test lung were set to 200 mL·kPa⁻¹ and 2 kPa·L⁻¹·s⁻¹, respectively. Experiments were conducted at 101, 203 and 284 kPa ambient pressure (1.0, 2.0 and 2.8 atmospheres absolute respectively). At each of the 5 PI values, the tidal volume (VT), peak inspiratory pressure (Ppeak) and peak inspiratory flow (Fpeak) displayed by the ventilator and the test lung were recorded for 20 cycles. Test lung data were considered the actual ventilation values. The ventilation data were compared among the three groups to evaluate the stability of the ventilator. At every PI, the Ppeak detected by the ventilator decreased slightly with increasing ambient pressure. The Fpeak values measured by the test lung decreased substantially as the ambient pressure increased. Nevertheless, the reduction in VT at 284 kPa and PI 30 cmH₂O (compared to performance at 101 kPa) was comparatively small (approximately 60 ml). In PCV mode this ventilator provided relatively stable VT across clinically relevant PI values to ambient pressures as high as 284 kPa. However, because Fpeak decreases at higher ambient pressure, some user adjustment might be necessary for precise VT maintenance during clinical use at higher PIs and ambient pressures.

Oscillatory airflow through the hypopharyngeal and supraglottic airway

Exercise-induced laryngeal obstruction (EILO) is a known cause of exertional dyspnoea, characterised by paradoxical inward collapse of laryngeal tissues. The pathophysiological mechanisms of EILO remain to be fully established, but insufficient mechanical resistance of laryngeal tissues to air-induced loads is hypothesised. It is understood that airflow and anatomic configurations of the airway play a key role in the wall pressure distribution of the larynx. While breathing is a cyclic process with directional changes of airflow, the literature is confined to steady, unidirectional airflow. It is necessary to assess the role of oscillatory airflow on the loads on the laryngeal airway. This study investigates the effect of oscillatory airflow on the laryngeal flow fields and air-induced loads. A computational fluid dynamics model of the upper respiratory tract (URT) is developed using the Reynolds-averaged Navier-Stokes equations. Five oscillatory airflow cases through a single geometry are considered, utilising sinusoidal breathing cycles with different breathing frequencies (24, 32 and 40 breaths per minute) and peak inspiratory flow rates (96, 168 and 240 L/min). Results include the airflow velocity distribution in the URT, and the air-induced pressure and forces. It is demonstrated that inspiratory velocity distribution varies with breathing frequency and intensity. The force acting on the URT walls are in-phase with the airflow rate and therefore exhibit quasi-steady behaviour. These findings are also reflected in the force vectors acting on the aryepiglottic folds and indicate that air-induced closure of the supraglottis in EILO is influenced by the breathing intensity rather than the breathing frequency.

Effects of breathing exercises on young swimmers’ respiratory system parameters and performance

Breathing exercises are widely used to enhance respiratory function and athletic performance. This study aimed to assess the efficacy of a modified exercise regimen on respiratory parameters and its effect on the performance of young swimmers in competition. Thirty-one swimmers aged 16–17 from various clubs in Latvia were selected, comprising an experimental group (n = 15, height: 174.36 ± 7.85 cm, weight: 65.80 ± 9.35 kg, body mass index: 21.60 ± 1.54) and a control group (n = 16, height: 180.78 ± 7.05 cm, weight: 69.90 ± 6.49 kg, body mass index: 21.40 ± 1.56). With an average of eight years of experience, participants trained for approximately 43–45 weeks annually (pool and gym sessions), with an average training duration of 20 ± 2 hours per week. Measurements were conducted on days one and 30, involving spirometry and swimming performance assessment based on the best results in the freestyle 100-meter distance. The experiment consisted of a modified breathing exercise performed thrice weekly for four weeks. Significant improvements were observed in the experimental group compared to the control group in forced vital capacity (p = 0.02), peak inspiratory flow (p = 0.001), and performance (p = 0.001), with p-values < 0.05. However, no significant changes were noted in peak expiratory flow (p = 0.46 > 0.05). The findings indicate that modified breathing exercises effectively enhance respiratory parameters and performance in competitive swimmers.

Post-insufflation diaphragm contractions in patients receiving various modes of mechanical ventilation

BackgroundDuring mechanical ventilation, post-insufflation diaphragm contractions (PIDCs) are non-physiologic and could be injurious. PIDCs could be frequent during reverse-triggering, where diaphragm contractions follow the ventilator rhythm. Whether PIDCs happens with different modes of assisted ventilation is unknown. In mechanically ventilated patients with hypoxemic respiratory failure, we aimed to examine whether PIDCs are associated with ventilator settings, patients’ characteristics or both.MethodsOne-hour recordings of diaphragm electromyography (EAdi), airway pressure and flow were collected once per day for up to five days from intubation until full recovery of diaphragm activity or death. Each breath was classified as mandatory (without-reverse-triggering), reverse-triggering, or patient triggered. Reverse triggering was further subclassified according to EAdi timing relative to ventilator cycle or reverse triggering leading to breath-stacking. EAdi timing (onset, offset), peak and neural inspiratory time (Tineuro) were measured breath-by-breath and compared to the ventilator expiratory time. A multivariable logistic regression model was used to investigate factors independently associated with PIDCs, including EAdi timing, amplitude, Tineuro, ventilator settings and APACHE II.ResultsForty-seven patients (median[25%-75%IQR] age: 63[52–77] years, BMI: 24.9[22.9–33.7] kg/m2, 49% male, APACHE II: 21[19–28]) contributed 2 ± 1 recordings each, totaling 183,962 breaths. PIDCs occurred in 74% of reverse-triggering, 27% of pressure support breaths, 21% of assist-control breaths, 5% of Neurally Adjusted Ventilatory Assist (NAVA) breaths. PIDCs were associated with higher EAdi peak (odds ratio [OR][95%CI] 1.01[1.01;1.01], longer Tineuro (OR 37.59[34.50;40.98]), shorter ventilator inspiratory time (OR 0.27[0.24;0.30]), high peak inspiratory flow (OR 0.22[0.20;0.26]), and small tidal volumes (OR 0.31[0.25;0.37]) (all P ≤ 0.008). NAVA was associated with absence of PIDCs (OR 0.03[0.02;0.03]; P < 0.001). Reverse triggering was characterized by lower EAdi peak than breaths triggered under pressure support and associated with small tidal volume and shorter set inspiratory time than breaths triggered under assist-control (all P < 0.05). Reverse triggering leading to breath stacking was characterized by higher peak EAdi and longer Tineuro and associated with small tidal volumes compared to all other reverse-triggering phenotypes (all P < 0.05).ConclusionsIn critically ill mechanically ventilated patients, PIDCs and reverse triggering phenotypes were associated with potentially modifiable factors, including ventilator settings. Proportional modes like NAVA represent a solution abolishing PIDCs.

Influence of acclimatization time on barometric whole-body plethysmography in cats with lower airway disease.

Barometric whole-body plethysmography (BWBP) is used as a noninvasive method to assess lung function in cats with lower airway disease (LAD). The duration of the acclimatization period in the measuring chamber varies between the studies. To assess the influence of acclimatization time on variables indicative of lung function. Twenty-four client-owned cats with LAD and 8 healthy cats. In the prospective case-control study for each cat, a 30-minute dataset was collected. Data for the three 10-minute periods were statistically compared. The variables pause (T1 median: 0.8, range: [0.7-1]; T3: 0.9 [0.8-1.1]; P ≤ .01), peak inspiratory flow (PIF; T1: 84.9 [71.6-112.7]; T3: 75 [63.6-108.3]; P ≤ .001), peak expiratory flow (PEF; T1: 53.2 [41.5-76.6]; T3: 42.5 [34.6-57.8]; P ≤ .01), and a quotient of PEF and expiratory flow at 50% expired volume (PEF/EF50; T1: 1.2 [1.1-1.4]; T3: 1.2 [1.1-1.5]; P ≤ .01) varied significantly between first and third time period in cats with LAD. In healthy cats PIF (T1: 76.4 [66.3-85.2]; T2: 69.5 [58.3-85.2]; P ≤ .01), PEF (T1: 40 [32.8-58.6]; T2: 34.3, [29.8-44.6]; P ≤ .01), and PEF/EF50 (T1: 13.1 [11.6-14.6]; T3: 13.6 [12.4-16.3]; P ≤ .01) changed significantly between first and second time period. Enhanced pause did not change significantly in either group. Acclimatization time has a significant influence on multiple variables in BWBP. Manual correction of the data for tidal breathing flow-volume loop might be necessary.

Impact of Preliminary Bronchodilator Dose in Chronic Obstructive Pulmonary Disease Patients With Suboptimal Peak Inspiratory Flow

Impact of Preliminary Bronchodilator Dose in Chronic Obstructive Pulmonary Disease Patients With Suboptimal Peak Inspiratory Flow

Early comprehensive pulmonary rehabilitation for hospitalized patients with acute ex-acerbation of chronic obstructive pulmonary disease: a randomized controlled trial.

To investigate whether an early comprehensive pulmonary rehabilitation intervention initiated during hospital admission is safe and effective for patients with acute exacerbation of chronic obstructive pulmonary disease. Prospective randomized controlled study. Patients with acute exacerbation of chronic obstructive pulmonary disease. In total, 108 patients were randomized to the early comprehensive pulmonary rehabilitation and usual care groups within 48 hours. The 6-min walking distance, quality of life, breathlessness, and inspiratory muscle strength were measured on admission and discharge. Any adverse events of pulmonary rehabilitation were recorded. On discharge, the patients in the early comprehensive pulmonary rehabilitation group had a more significant improvement in the 6-min walking distance (47.5 vs 23.0, p = 0.04). There was no significant difference in quality of life and breathlessness between the 2 groups. In the early comprehensive pulmonary rehabilitation group, inspiratory muscle strength and peak inspiratory flow were significantly improved, and the changes were much more pronounced than in the usual care group. There were no adverse events. Early comprehensive pulmonary rehabilitation is safe and effective for hospitalized patients with acute exacerbation of chronic obstructive pulmonary disease, and should be performed during the early stage of hospitalization.

Functional and Structural Changes in Diaphragm Neuromuscular Junctions in Early Aging.

Age-related impairment of the diaphragm causes respiratory complications. Neuromuscular junction (NMJ) dysfunction can be one of the triggering events in diaphragm weaknesses in old age. Prominent structural and functional alterations in diaphragm NMJs were described in elderly rodents, but NMJ changes in middle age remain unclear. Here, we compared diaphragm muscles from young adult (3 months) and middle-aged (12 months) BALB/c mice. Microelectrode recordings, immunofluorescent staining, electron microscopy, myography, and whole-body plethysmography were used. We revealed presynaptic (i) and postsynaptic (ii) changes. The former (i) included an increase in both action potential propagation velocity and neurotransmitter release evoked by low-, moderate-, and high-frequency activity but a decrease in immunoexpression of synapsin 1 and synaptic vesicle clustering. The latter (ii) consisted of a decrease in currents via nicotinic acetylcholine receptors and the area of their distribution. These NMJ changes correlated with increased contractile responses to moderate- to high-frequency nerve activation. Additionally, we found alterations in the pattern of respiration (an increase in peak inspiratory flow and a tendency of elevation of the tidal volume), which imply increased diaphragm activity in middle-aged mice. We conclude that enhancement of neuromuscular communication (due to presynaptic mechanism) accompanied by improved contractile responses occurs in the diaphragm in early aging.

Dry Powder Inhaler Use in Primary School Aged Children with Asthma: A Systematic Review

ObjectiveAsthma is the most common chronic disease in children. Dry powder inhalers (DPI) are effective for medication delivery in adults and adolescents, and provide a lower environmental footprint and more portability when compared to metered dose inhaler (MDI) with spacer. They require specific technique, and it is necessary to ascertain whether they can be used in younger age groups. We aimed to assess evidence regarding whether primary school aged (5–11 years) children can use DPI with adequate technique both during stable and acute asthma.DesignOvid MEDLINE, Embase and PubMed were searched for studies assessing DPI use in children aged 5–11 years with asthma or wheeze. Results of studies were synthesised by study design and outcome measure.ResultsThirty-eight studies were identified for analysis. These were analysed in three groups: (1) 25 studies assessing children's ability to use DPI by peak inspiratory flow measurement, (2) 10 studies assessing children's ability to use DPI by physician assessment, and (3) three studies measuring efficacy of DPI compared to gold standard (MDI with spacer). Five studies included children during acute exacerbations.ConclusionThe majority of primary school aged children have the ability to use a DPI with adequate training, support and practice. Some younger children may have difficulties, and clinician assessment and ongoing review is crucial in determining which children are likely to benefit from a DPI. Consistent correct use and adherence remains a challenge, but this is also an issue with MDI plus spacer and does not appear to be significantly worse with DPI. Evidence of the use of DPI during acute illness is limited, and more studies are required in this setting.

Comparisons between In-Check DIAL® and PF810® in evaluation and training inspiratory capacity for using dry powder inhalers

BackgroundDry powder inhalers (DPIs) rely on both internal resistance and patients’ inspiratory capacity for effective operation. Optimal inspiratory technique is crucial for DPI users. This study assessed the accuracy and repeatability of two available devices, PF810® and In-Check DIAL®, and analyzed their measurement errors and consistency in detecting inspiratory capacity.MethodsThe accuracy and repeatability of peak inspiratory flow (PIF) and forced inspiratory vital capacity (FIVC) against various internal resistances of the two devices were assessed using standard waveforms generated by a breathing simulator. The agreement of PIF measurements between the two devices in healthy volunteers and chronic obstructive pulmonary disease (COPD) patients was analyzed with the intraclass correlation coefficient and Bland–Altman graphical analysis.ResultsPF810® showed great accuracy and repeatability in measuring PIF, except for square waveforms at the lowest flow rate (20 L/min). In-Check DIAL® exhibited poor accuracy against high resistance levels. In scenarios with no resistance, In-Check DIAL® had significantly smaller measurement errors than PF810®, but larger errors against high resistance levels. The two devices showed excellent agreement (ICC > 0.80, P < 0.05), except for healthy volunteers against medium to high resistance (R3-R5) where the ICC was insignificant. Bland–Altman plots indicated small disagreements between the two devices for both healthy volunteers and COPD patients.ConclusionsIn-Check DIAL® exhibited poor accuracy and larger measurement errors than PF810® when detecting PIFs against higher internal resistances. However, its good performance against lower internal resistances, along with its cost-effectiveness and convenience made it appropriate for primary care. PF810® showed good accuracy and repeatability and could detect additional parameters of inspiratory capacity beyond PIF, though required further studies to confirm its clinical benefits.

Changes in Peak Inspiratory Flow After Acute Bronchodilation: An Observational Study of Patients with Stable Chronic Obstructive Pulmonary Disease.

Introduction: Identifying factors influencing peak inspiratory flow (PIF) is essential for aerosol drug delivery in stable patients with chronic obstructive pulmonary disease. While a minimum PIF for dry powder inhalers (DPIs) is established, acute bronchodilator (BD) effects on PIF remain unknown. Materials and Methods: An inspiratory flow meter (In-Check™ DIAL) was used to measure PIF in stable patients during a 24-week observational cross-sectional study. Additionally, bronchodilator responsiveness (BDR) was determined using the In-Check DIAL device and spirometry. Patients received four puffs of albuterol, and pre- and post-BD PIF, forced expiratory volume in one second (FEV1), and forced vital capacity were measured. Sixty-three patients completed acute BDR data collection from July 31, 2019, to November 9, 2021. Primary endpoints were pre- and post-BD spirometry and PIF. Statistical analyses included PIF correlations with FEV1. BD change was assessed according to inhaler resistance and sex (subgroup analysis). Results: Median patient age was 64.8 years, 85.7% were non-Hispanic White, and 57.1% were female. The median increase in absolute PIF (In-Check DIAL) was 5.0 L/min, and the % PIF change was 8.9%. With albuterol, 57.1% experienced a PIF BD change >5.0%, whereas 49.2% experienced a change >10.0%. Similarly, 55.6% experienced an FEV1 BD change >5.0% and 28.6% had a >10.0% FEV1 BD change with albuterol. PIF was weakly correlated with FEV1 BD change (absolute; % PIF; r = 0.28 [p = 0.02]; r = 0.21 [p = 0.11]). Pre- and post-BD median PIF were 75.5 and 83.5 L/min for low-to-medium-resistance DPI and 45.0 and 52.0 L/min for high-resistance, respectively. The median increases in pre- and post-BD PIF were 9.0 L/min in males and 4.5 L/min in females. In contrast to when using the In-Check DIAL device, we observed no consistent bronchodilatory effects on PIF measured by spirometry. Conclusions: Using the In-Check DIAL device, ∼50% of patients experienced >10% PIF increase after acute BD, potentially enhancing medication lung deposition. Further research is required to understand PIF's impact on medication delivery. ClinicalTrials.gov Identifier: NCT04168775.

The effects of circuit training versus high-intensity interval training on the endurance of volleyball athletes: a randomized controlled trial

Despite its intermittent nature, volleyball places significance on a high aerobic capacity, particularly evident in multiset games that demand sustained high-performance levels. Various training approaches exist to enhance the endurance of volleyball athletes. Thus, the fundamental aim of this research is to examine the contrasting effects of utilizing high-intensity interval training (HIIT) and circuit training methods to enhance volleyball athletes' endurance. The study used an Experimental group that partook in a HIIT training regime, and a Contrast group that undertook a Circuit training program. Thirty male volleyball players aged between 17 and 22 years (M=19.14; SD±1.61) were purposefully selected for the study and split into Contrast and Experimental groups of 15 each. At the beginning and end of the intervention programs both groups underwent physiological assessments for Maximum Oxygen Consumption (VO2max), Heart Rate Recovery (HRR), Peak Inspiratory Flow (PIF), Peak Expiratory Flow (PEF), and Force Vital Capacity (FVC). As result a meaningful Time x Group interaction for the VO2max, HRR, PIF, PEF and FVC was observed. This represents a significant improvement in the treatment group (p &lt; 0.001). No material change was observed in the comparison group. Findings revealed that the HIIT training approach outperformed the circuit training method in enhancing volleyball athletes' endurance. Consequently, it is should be beneficial for volleyball players to incorporate HIIT into their standard training regimens. Keywords: VO2max; physiology; sport; exercise; aerobic capacity.

Clinical characteristics of chronic obstructive pulmonary disease patients with superoptimal peak inspiratory flow rate

Characteristics of chronic obstructive pulmonary disease (COPD) patients with superoptimal peak inspiratory flow rates (PIFR) has not been thoroughly investigated. This study aimed to compare the characteristics between COPD patients with superoptimal PIFR and those with optimal and sub-optimal PIFR. PIFR was measured using In-Check DIAL G16 and categorized into sub-optimal (PIFR lower than that required by the patient’s device), optimal, and superoptimal (peak PIFR ≥ 90 L/min). Considering COPD patients with sub-optimal PIFR as the reference group, analyses were performed to identify PIFR-related factors. Subgroup analysis was performed according to the forced expiratory volume in 1 s (FEV1) % of the predicted value (%pred). Among 444 post-bronchodilator-confirmed COPD patients from seven tertiary hospitals in South Korea, 98, 223, and 123 were classified into the sub-optimal, optimal, and superoptimal PIFR groups, respectively. The superoptimal PIFR group were younger, had an increased proportion of males, a higher body mass index, lowest number of comorbidities and less frequent exacerbation in the previous year, as well as the highest forced vital capacity %pred. The adjusted odds ratio for frequent exacerbation in the previous year was lower in the superoptimal PIFR group than in the sub-optimal PIFR group and was more pronounced in patients with an FEV1%pred of < 70%. COPD patients with superoptimal PIFR have clinical characteristics different from those patients with the sub-optimal and optimal PIFR. Having a high inspiratory flow may be a favorable trait in COPD.

Tropine exacerbates the ventilatory depressant actions of fentanyl in freely-moving rats.

Our lab is investigating the efficacy profiles of tropine analogs against opioid-induced respiratory depression. The companion manuscript reports that the cell-permeant tropeine, tropine ester (Ibutropin), produces a rapid and sustained reversal of the deleterious actions of fentanyl on breathing, alveolar-arterial (A-a) gradient (i.e., index of alveolar gas exchange), and arterial blood-gas (ABG) chemistry in freely-moving male Sprague Dawley rats, while not compromising fentanyl analgesia. We report here that in contrast to Ibutropin, the injection of the parent molecule, tropine (200μmol/kg, IV), worsens the adverse actions of fentanyl (75μg/kg, IV) on ventilatory parameters (e.g., frequency of breathing, tidal volume, minute ventilation, peak inspiratory and expiratory flows, and inspiratory and expiratory drives), A-a gradient, ABG chemistry (e.g., pH, pCO2, pO2, and sO2), and sedation (i.e., the righting reflex), while not affecting fentanyl antinociception (i.e., the tail-flick latency) in freely-moving male Sprague Dawley rats. These data suggest that tropine augments opioid receptor-induced signaling events that mediate the actions of fentanyl on breathing and alveolar gas exchange. The opposite effects of Ibutropin and tropine may result from the ability of Ibutropin to readily enter peripheral and central cells. Of direct relevance is that tropine, resulting from the hydrolysis of Ibutropin, would combat the Ibutropin-induced reversal of the adverse effects of fentanyl. Because numerous drug classes, such as cocaine, atropine, and neuromuscular blocking drugs contain a tropine moiety, it is possible that their hydrolysis to tropine has unexpected/unintended consequences. Indeed, others have found that tropine exerts the same behavioral profile as cocaine upon central administration. Together, these data add valuable information about the pharmacological properties of tropine.