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Prior studies of muscle blood flow and muscle-specific oxygen consumption have required invasive injection of dye and magnetic resonance imaging, respectively. Such measures have limited utility for continuous monitoring of the respiratory muscles. Frequency-domain near-infrared spectroscopy and diffuse correlation spectroscopy (FD-NIRS & DCS) can provide continuous surrogate measures of blood flow index (BFi) and metabolic rate of oxygen consumption (MRO2). This study aimed to validate sternocleidomastoid FD-NIRS & DCS outcomes against electromyography (EMG) and mouth pressure (Pm) during incremental inspiratory threshold loading (ITL). Six female and six male healthy adults (means ± SD; 30 ± 7 yr, maximum inspiratory pressure 118 ± 61 cmH2O) performed incremental ITL starting at low loads (8 ± 2 cmH2O) followed by 50-g increments every 2 min until task failure. FD-NIRS & DCS continuously measured sternocleidomastoid oxygenated and deoxygenated hemoglobin + myoglobin (oxy/deoxy[Hb + Mb]), tissue saturation of oxygen (StO2), BFi, and MRO2. Ventilatory parameters including inspiratory Pm were also evaluated. Pm increased during incremental ITL (P < 0.05), reaching −47[−74 to −34] cmH2O (median [IQR: 25%–75%]) at task failure. Ventilatory parameters were constant throughout ITL (all P > 0.05). Sternocleidomastoid BFi and MRO2 increased from the start of the ITL (both P < 0.05). Deoxy[Hb + Mb] increased close to task failure, concomitantly with a constant increase in MRO2, and decreased StO2. Sternocleidomastoid deoxy[Hb + Mb], BFi, StO2, and MRO2 obtained during ITL via FD-NIRS & DCS correlated with sternocleidomastoid EMG (all P < 0.05). In healthy adults, FD-NIRS & DCS can provide continuous surrogate measures of respiratory BFi and MRO2. Increasing sternocleidomastoid oxygen consumption near task failure was associated with increased oxygen extraction and reduced tissue saturation. NEW & NOTEWORTHY: This study introduces a novel approach, frequency-domain near-infrared spectroscopy and diffuse correlation spectroscopy (FD-NIRS & DCS), for noninvasive continuous monitoring of respiratory muscle blood flow and metabolic rate of oxygen consumption. Unlike prior methods involving invasive dye injection and magnetic resonance imaging, FD-NIRS & DCS offers the advantage of continuous measurement without the need for invasive procedures. It holds promise for advancing muscle physiology understanding and opens avenues for real-time monitoring of respiratory muscles. [ABSTRACT FROM AUTHOR]

Purpose This study aimed to investigate whether patients with chronic obstructive pulmonary disease (COPD) presenting asthma overlap (ACO) benefit similarly in comparison to patients with only COPD after a 12-week high-intensity exercise training (ET) program. Methods Subjects with a diagnosis of COPD alone or ACO were evaluated and compared before and after a high-intensity ET program composed of walking and cycling plus strengthening exercises of the upper and lower limbs (3 days/week, 3 months, 36 sessions). Assessments included spirometry, bioelectrical impedance, 6-min walk test (6MWT), London Chest Activity of Daily Living Scale (LCADL), Hospital anxiety and depression Scale, modified Medical Research Council Scale (mMRC), Saint George Respiratory Questionnaire (SGRQ), and respiratory and peripheral muscle strength [manovacuometry and 1-repetition maximum test (quadriceps femoris, biceps and triceps brachialis), respectively]. ACO was defined according to Sin et al. (Eur Respir J 48(3):664-673, 2016). Results The sample was composed of 74 subjects (57% male, age 67 ± 8 years, BMI 26 (21-32) kg/m.sup.2, FEV.sub.1 47 ± 17%predicted), and 12 (16%) of them were classified as presenting ACO. Both groups improved pulmonary function, 6MWT, peripheral and inspiratory muscle strength, LCADL, and SGRQ after ET (p < 0.005 for all). There were no significant interactions between ACO and COPD on ET effects (p > 0.05 for all). Likewise, there was no difference in the proportion of patients achieving the minimum clinical important difference for 6MWT and mMRC. Conclusion High-intensity exercise training generates similar benefits in patients with COPD regardless of whether presenting asthma overlap or not., Author(s): Antenor Rodrigues [sup.1] , Joice Mara de Oliveira [sup.2] , Karina Couto Furlanetto [sup.2] , Felipe Vilaça Cavallari Machado [sup.1] , Letícia Fernandes Belo [sup.1] , Lorena Paltanin Schneider [...]

Purpose Whether the difference in the impact of chronic obstructive pulmonary disease (COPD) on the functional status of men and women stems from clinical distinctions or to the measuring instrument used is unclear. Like most instruments for assessing functional limitation in COPD, the interpretation of the results of the London Chest Activity of Daily Living (LCADL) scale is limited because a lack of a valid cutoff point to this scale. For that, this study sought to compare the functional status between men and women with COPD; and propose a cutoff point for LCADL capable of discriminating the prognosis of these individuals. Methods A sample of 138 subjects with moderate-severe COPD was evaluated by the LCADL. The percentage of the individual maximum score was used to obtain a cutoff point capable of discriminating patients with the worse prognosis according to the BODE Index. The cutoff point was also tested in an independent sample (n = 70). Results Regarding the total score, domestic and leisure domains of the LCADL, men had better scores than women (P [less than or equal to] 0.01). The cutoff point found was 37% (area under the curve = 0.70, 95% confidence interval = 0.60-0.80, sensitivity = 0.55 and specificity = 0.74). Individuals who scored [greater than or equal to] 37% had a worse prognosis and level of physical activities of daily living than those who scored below (P [less than or equal to] 0.02). Conclusion When evaluated by the LCADL, men and women with COPD present difference in the functional status. The established cutoff point (37%) adequately discriminates individuals regarding the prognosis, contributing to improve the interpretation capacity of the LCADL., Author(s): Letícia Fernandes Belo [sup.1] , Antenor Rodrigues [sup.1] [sup.2] , Thaís Paes [sup.1] , Felipe Vilaça Cavallari Machado [sup.1] , Lorena Paltanin Schneider [sup.1] , Ana Paula Vicentin [sup.1] [...]

Reverse triggering dyssynchrony is a frequent phenomenon recently recognized in sedated critically ill patients under controlled ventilation. It occurs in at least 30 to 55% of these patients and often occurs in the transition from fully passive to assisted mechanical ventilation. During reverse triggering, patient´s inspiratory efforts start after the passive insufflation by mechanical breaths. The most often referred mechanism is the entrainment of the patient´s intrinsic respiratory rhythm from the brainstem respiratory centers to periodic mechanical insufflations from the ventilator. However, reverse triggering might also occur because of local reflexes without involving the respiratory rhythm generator in the brainstem. Reverse triggering is observed during the acute phase of the disease, when patients may be susceptible to potential deleterious consequences of injurious or asynchronous efforts. Diagnosing reverse triggering might be challenging and can easily be missed. Inspection of ventilator waveforms or more sophisticated methods such as electrical activity of the diaphragm or esophageal pressure can be used for diagnosis. The occurrence of reverse triggering might have clinical consequences. Based on physiological data, reverse triggering might be beneficial or injurious for the diaphragm and the lung depending on the magnitude of the inspiratory effort. Reverse triggering can cause breath-stacking and loss of protective lung ventilation when triggering a second cycle. Little is known about how to manage patients with reverse triggering; however, available evidence can guide management based on physiological principles. [ABSTRACT FROM AUTHOR]