[Important step of weaning from mechanical ventilation: accurate assessment of respiratory muscle strength].

Mechanical ventilation (MV) is a powerful mean to rescue patients with respiratory failure. In view of the different etiology and basic respiratory function of patients with respiratory failure, weaning failure often occurs. Prolonged MV time is often accompanied by many complications. Thus, deeply understanding the pathophysiological changes of respiratory failure and strengthen monitoring of respiratory mechanics are helpful to optimize MV parameter settings, reduce ventilator-induced lung injury and wean from MV as early as possible. A successful weaning from MV depends on many factors, the most important factors are respiratory muscle strength, respiratory load and respiratory drive. Spontaneous breathing trial (SBT) is an important part of weaning process. The main purpose of implementing SBT is to screen patients and opportunities to weaning from MV, and find reversible reasons for not passing SBT. Because the accuracy of SBT in assessing weaning prognosis is about 85%, it is not adequate for difficult weaning patients. Standardized measurement of weaning indicators for patients with difficulty weaning is conducive to accurate assessment of respiratory muscle strength and improve the success rate of weaning from MV.

Investigation of the relationship between functional movement and respiratory muscle strength in professional football players and sedentary individuals: A controlled trial.

INTRODUCTION: Functional Movement Screening (FMS) is a battery used for injury prediction, identifying asymmetry and weak connections in basic functional movement patterns. The muscles assessed in FMS are also respiratory muscles. Therefore, FMS scores were thought to be related to respiratory muscle strength. The aim of our study was to examine the relationship between Functional Movement Screen and respiratory muscles strength in professional football players and sedentary individuals. METHODS: The study included 23 male professional football players (mean age: 25 ± 6.22 years) and 22 sedantery healthy volunteers (mean age: 24.54 ± 2.75 years). Functional Movement Screen tests were applied by the certified researcher. Respiratory muscle strength measurement were measured with an additional mouth apparatus attached to the portable spirometer 'Pony FX Desktop Spirometry' device. RESULTS: Trunk stability push-up (p = 0.01; r = 0.490), rotational stability (p = 0.025; r = 0,519), and Functional Movement Screen total score (p = 0.02; r = 0.568) with maximum expiratory pressure were moderately positive correlated in professional football players. In the sedantery group, Functional Movement Screen sub-parameters were not correlated respiratory muscle strength (p > 0.05). DISCUSSION: The higher Functional Movement Screen total score in professional football players and their skills in functional movements that require trunk and core stabilization increase expiratory muscle strength were found compared to sedentary individuals. CONCLUSION: Increase of expiratory muscle strength may be useful in the treatment program when the aim was to Improving functional movement patterns, trunk and core stabilization.

Physiotherapy interventions on chest wall mobility in obstructive lung diseases: A systematic review.

PURPOSE: The aim of this systematic review was to investigate the effectiveness of physiotherapy interventions on chest mobility in obstructive lung diseases. METHODS: Searches were performed in PEDro, Pubmed and Cochrane Central Register of Controlled Trials databases without language restrictions between 2010 and 25th December 2020. Randomized controlled trials (RCTs) investigating physiotherapy interventions on chest wall mobility were included. Two independent reviewers screened studies, extracted data, and assessed methodological quality of included studies. The assessment of risk of bias was conducted using the PEDro scale for RCTs. The articles were excluded if they have less than 5 out of 10 score. RESULTS: Five studies included had good to excellent quality. A total of 139 patients were included in all RCTs. Intervention duration ranged from a single session to 12 weeks and the intervention schedules varied, consisting of 1-24 sessions, lasting 5-45 min per sessions. Three studies used respiratory muscle stretching and releasing techniques, one study combined respiratory muscle stretching with aerobic training, and one study planned diaphragmatic breathing. Four studies assessed chest wall mobility with optoelectronic plethysmography, whereas one study used measuring tape. CONCLUSIONS: The result of this first systematic review that investigates the effects of physiotherapy interventions on chest wall mobility in obstructive lung diseases suggests that more and better quality RCTs with objective measurement tools are required.

A comprehensive physical functional assessment of survivors of critical care unit stay due to COVID-19.

OBJECTIVE: To examine the physical function and respiratory muscle strength of patients - who recovered from critical COVID-19 - after intensive care unit discharge to the ward on Days one (D1) and seven (D7), and to investigate variables associated with functional impairment. METHODS: This was a prospective cohort study of adult patients with COVID-19 who needed invasive mechanical ventilation, non-invasive ventilation or high-flow nasal cannula and were discharged from the intensive care unit to the ward. Participants were submitted to Medical Research Council sum-score, handgrip strength, maximal inspiratory pressure, maximal expiratory pressure, and short physical performance battery tests. Participants were grouped into two groups according to their need for invasive ventilation: the Invasive Mechanical Ventilation Group (IMV Group) and the Non-Invasive Mechanical Ventilation Group (Non-IMV Group). RESULTS: Patients in the IMV Group (n = 31) were younger and had higher Sequential Organ Failure Assessment scores than those in the Non-IMV Group (n = 33). The short physical performance battery scores (range 0 - 12) on D1 and D7 were 6.1 ± 4.3 and 7.3 ± 3.8, respectively for the Non-Invasive Mechanical Ventilation Group, and 1.3 ± 2.5 and 2.6 ± 3.7, respectively for the IMV Group. The prevalence of intensive care unit-acquired weakness on D7 was 13% for the Non-IMV Group and 72% for the IMV Group. The maximal inspiratory pressure, maximal expiratory pressure, and handgrip strength increased on D7 in both groups, but the maximal expiratory pressure and handgrip strength were still weak. Only maximal inspiratory pressure was recovered (i.e., > 80% of the predicted value) in the Non-IMV Group. Female sex, and the need and duration of invasive mechanical were independently and negatively associated with the short physical performance battery score and handgrip strength. CONCLUSION: Patients who recovered from critical COVID-19 and who received invasive mechanical ventilation presented greater disability than those who were not invasively ventilated. However, they both showed marginal functional improvement during early recovery, regardless of the need for invasive mechanical ventilation. This might highlight the severity of disability caused by SARS-CoV-2.

Diaphragm thickness and mobility elicited by two different modalities of inspiratory muscle loading in heart failure participants: A randomized crossover study.

OBJECTIVES: To analyze diaphragmatic thickness, at end-inspiration and end-expiration, diaphragmatic thickening index and mobility via US under two different modalities of inspiratory muscle loading, in two different modalities of inspiratory muscle loading and different load intensities at full-vital capacity maneuvers and the relationship between diaphragmatic thickness with pulmonary function tests in participants with HF. METHODS: This randomized crossover trial, enrolled with 17 HF subjects, evaluated diaphragm thickness (Tdi, mm), fractional thickness (TFdi, %), and mobility (mm) US during low and high intensities (30% and 60% of maximal inspiratory pressure-MIP) with two modalities of inspiratory muscle loading mechanical threshold loading (MTL) and tapered flow-resistive loading (TFRL). RESULTS: Both MTL and TFRL produced a increase in Tdi, but only with high intensity loading compared to baseline-2.21 (0.26) vs. 2.68 (0.33) and 2.73 (0.44) mm; p = .01. TFdi was greater than baseline under all conditions, except during low intensity of TFRL. Diaphragm mobility was greater than baseline under all conditions, and high intensity of TFRL elicited greater mobility compared to all other conditions. Additionally, baseline Tdi was moderately correlated with pulmonary function tests. CONCLUSIONS: MTL and TFRL modalities elicit similar increases in diaphragm thickness at loads, but only during high intensity loading it was greater than baseline. Diaphragm mobility was significantly greater than baseline under both loads and devices, and at high intensity compared to low intensity, although TFRL produced greater mobility compared to modalities of inspiratory muscle loading. There is an association between diaphragm thickness and pulmonary function tests.

Respiratory muscle strength can improve the prognostic assessment in COPD.

Impaired lung function, respiratory muscle weakness and exercise intolerance are present in COPD and contribute to poor prognosis. However, the contribution of the combination of these manifestations to define prognosis in COPD is still unknown. This study aimed to define cut-off points for both inspiratory and expiratory muscle strength (MIP and MEP, respectively) for mortality prediction over 42-months in patients with COPD, and to investigate its combination with other noninvasive established prognostic measures (FEV1, V̇O2peak and 6MWD) to improve risk identification. Patients with COPD performed pulmonary function, respiratory muscle strength, six-minute walk and cardiopulmonary exercise tests, and were followed over 42 months to analyze all-cause mortality. A total of 79 patients were included. The sample was mostly (91.1%) comprised of severe (n = 37) and very severe (n = 34) COPD, and 43 (54%) patients died during the follow-up period. Cut-points of ≤ 55 and ≤ 80 cmH2O for MIP and MEP, respectively, were associated with increased risk of death (log-rank p = 0.0001 for both MIP and MEP) in 42 months. Furthermore, MIP and MEP substantially improved the mortality risk assessment when combined with FEV1 (log-ranks p = 0.006 for MIP and p < 0.001 for MEP), V̇O2peak (log-rank: p < 0.001 for both MIP and MEP) and 6MWD (log-ranks: p = 0.005 for MIP; p = 0.015 for MEP). Thus, patients severely affected by COPD presenting MIP ≤ 55 and/or MEP ≤ 80 cmH2O are at increased risk of mortality. Furthermore, MIP and MEP substantially improve the mortality risk assessment when combined with FEV1, V̇O2peak and 6MWD in patients with COPD.

Effects of different inspiratory muscle training protocols on functional exercise capacity and respiratory and peripheral muscle strength in patients with chronic kidney disease: a randomized study.

BACKGROUND: Pathological changes were observed in the diaphragm due to abnormal renal function in chronic kidney disease (CKD). Inspiratory muscle training (IMT) has been suggested for patients with CKD; however, the most appropriate intensity for IMT has not been determined. Therefore, this study aimed to investigate the effects of different IMT protocols on respiratory muscle strength, quadriceps femoris muscle strength (QMS), handgrip muscle strength (HGS), functional exercise capacity, quality of life (QoL), pulmonary function, dyspnoea, fatigue, balance, and physical activity (PA) levels in patients with CKD. METHODS: This randomized, controlled, single-blind study included 47 patients and they were divided into three groups: Group 1 (n = 15, IMT with 10% maximal inspiratory pressure (MIP)), Group 2 (n = 16, IMT with 30% MIP), and Group 3(n = 16; IMT with 60% MIP). MIP, maximal expiratory pressure (MEP), 6-min walking test (6-MWT), QMS, HGS, QoL, pulmonary function, dyspnoea, fatigue, balance, and PA levels were assessed before and after eight weeks of IMT. RESULTS: Increases in MIP, %MIP, 6-MWT distance, and %6-MWT were significantly higher in Groups 2 and 3 than in Group 1 after IMT (p < 0.05). MEP, %MEP, FEF25-75%, QMS, HGS, and QoL significantly increased; dyspnoea and fatigue decreased in all groups (p < 0.05). FVC, PEF, and PA improved only in Group 2, and balance improved in Groups 1 and 2 (p < 0.05). CONCLUSIONS: IMT with 30% and 60% MIP similarly improves inspiratory muscle strength and functional exercise capacity. IMT with 30% is more effective in increasing PA. IMT is a beneficial method to enhance peripheral and expiratory muscle strength, respiratory function, QoL and balance, and reduce dyspnoea and fatigue. IMT with %30 could be an option for patients with CKD who do not tolerate higher intensities. TRIAL REGISTRATION: This study was retrospectively registered (NCT06401135, 06/05/2024).

Incremental Load Respiratory Muscle Training Improves Respiratory Muscle Strength and Pulmonary Function in Children with Bronchiectasis.

Methods: Participants underwent respiratory muscle training for 24 weeks. The main results were changes in respiratory muscle strength and pulmonary function indices (forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), FEV1/FVC, peak expiratory flow rate (PEF), forced expiratory flow 25-75% (FEF25-75%), and maximal midexpiratory flow 75/25 (MMEF75/25)) before, 12 weeks after, and 24 weeks after the intervention. The secondary outcomes were changes in the exercise load and work rate, exercise work, Leicester Cough Questionnaire (LCQ) scale, and Fatigue Severity Scale (FSS). Results: Compared with before the intervention, after 24 weeks of respiratory muscle training, the maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) were significantly enhanced (P < 0.05), while FVC, FEV1, and PEF were significantly increased (P < 0.01). FEF25-75 and MMEF75/25 values showed significant improvement compared to those before training (P < 0.05). The exercise loading, work, and exercise work rate of expiratory muscle training were significantly improved compared to those before intervention (P < 0.05). The LCQ score increased significantly (P < 0.001), and the FSS score decreased significantly (P < 0.001). Conclusion: Incremental load respiratory muscle training effectively improved children's lung function over the long term, improved the strength of their inspiratory and expiratory muscles, and improved their quality of life.

Internet of Things-Based Home Respiratory Muscle Training for Patients with Chronic Obstructive Pulmonary Disease: A Randomized Clinical Trial.

Purpose: Whether Internet of Things (IoT)-based home respiratory muscle training (RMT) benefits patients with comorbid chronic obstructive pulmonary disease (COPD) remains unclear. Therefore, this study aims to evaluate the effectiveness of IoT-based home RMT for patients with COPD. Patients and Methods: Seventy-eight patients with stable COPD were randomly divided into two groups. The control group received routine health education, while the intervention group received IoT-based home RMT (30 inspiratory muscle training [IMT] and 30 expiratory muscle training [EMT] in different respiratory cycles twice daily for 12 consecutive weeks). Assessments took place pre-intervention and 12 weeks post-intervention, including lung function tests, respiratory muscle strength tests, the mMRC dyspnea scale, CAT questionnaires, the HAMA scale, and 6-month COPD-related readmission after intervention. Results: Seventy-four patients with COPD were analyzed (intervention group = 38, control group = 36), and the mean age and FEV1 of the patients were 68.65 ± 7.40 years, 1.21 ± 0.54 L. Compared to those of the control population, the intervention group exhibited higher FEV1/FVC (48.23 ± 10.97 vs 54.32 ± 10.31, p = 0.016), MIP (41.72 ± 7.70 vs 47.82 ± 10.99, p = 0.008), and MEP (42.94 ± 7.85 vs 50.29 ± 15.74, p = 0.013); lower mMRC (2.00 [2.00-3.00] vs 1.50 [1.00-2.00], p < 0.001), CAT (17.00 [12.00-21.75] vs 11.00 [9.00-13.25], p < 0.001), and HAMA (7.00 [5.00-9.00] vs 2.00 [1.00-3.00], p < 0.001) scores; and a lower incidence rate of 6-month readmission (22% vs 5%, p = 0.033). Conclusion: Compared with no intervention, IoT-based home RMT may be a more beneficial intervention for patients with COPD.

Establishing an optimal diagnostic criterion for respiratory sarcopenia using peak expiratory flow rate.

BACKGROUND: The skeletal muscle changes as aging progresses, causing sarcopenia in the older adult population, which affects the respiratory muscles' mass, strength, and function. The optimal cut-off point of peak expiratory flow rate (PEFR) for respiratory sarcopenia (RS) diagnosis in accordance with sarcopenia identification is needed. AIM: To establish an optimal cut-off point of PEFR for RS diagnosis in community-dwelling Asian older women. METHODS: Sarcopenia diagnostic indicators were evaluated according to the Asian Working Group for Sarcopenia 2019 (AWGS) criteria. The respiratory parameters composed of respiratory muscle strength and respiratory function were evaluated by assessing maximal inspiratory pressure (MIP), percent predicted forced vital capacity (Pred FVC), and PEFR. RESULTS: A total of 325 community-dwelling older women were included in this study. PEFR was negatively associated with RS (OR: 0.440; 95% CI: 0.344-0.564). The area under the curve (AUC) of PEFR was 0.772 (p < 0.001). The optimal cut-off point of PEFR for RS diagnosis was 3.4 l/s (sensitivity, 63.8%; specificity, 77.3%). Significant differences were found between the robust, possible sarcopenia, sarcopenia, and RS groups in terms of both sarcopenia diagnostic indicators and respiratory parameters (p < 0.05). CONCLUSIONS: The cut-off point of PEFR can be used as a reasonable standard for RS diagnosis. This study finding can serve as a cornerstone for developing concrete criteria of RS in older women, supporting clinical judgment, which is crucial for providing appropriate treatment through accurate diagnosis.

The effect of respiratory muscle training on children and adolescents with cystic fibrosis: a systematic review and meta-analysis.

BACKGROUND: Cystic fibrosis is a chronic genetic disease that can affect the function of the respiratory system. Previous reviews of the effects of respiratory muscle training in people with cystic fibrosis are uncertain and do not consider the effect of age on disease progression. This systematic review aims to determine the effectiveness of respiratory muscle training in the clinical outcomes of children and adolescents with cystic fibrosis. METHODS: Up to July 2023, electronic databases and clinical trial registries were searched. Controlled clinical trials comparing respiratory muscle training with sham intervention or no intervention in children and adolescents with cystic fibrosis. The primary outcomes were respiratory muscle strength, respiratory muscle endurance, lung function, and cough. Secondary outcomes included exercise capacity, quality of life and adverse events. Two review authors independently extracted data and assessed study quality using the Cochrane Risk of Bias Tool 2. The certainty of the evidence was assessed according to the GRADE approach. Meta-analyses where possible; otherwise, take a qualitative approach. RESULTS: Six studies with a total of 151 participants met the inclusion criteria for this review. Two of the six included studies were published in abstract form only, limiting the available information. Four studies were parallel studies and two were cross-over designs. There were significant differences in the methods and quality of the methodology included in the studies. The pooled data showed no difference in respiratory muscle strength, lung function, and exercise capacity between the treatment and control groups. However, subgroup analyses suggest that inspiratory muscle training is beneficial in increasing maximal inspiratory pressure, and qualitative analyses suggest that respiratory muscle training may benefit respiratory muscle endurance without any adverse effects. CONCLUSIONS: This systematic review and meta-analysis indicate that although the level of evidence indicating the benefits of respiratory muscle training is low, its clinical significance suggests that we further study the methodological quality to determine the effectiveness of training. TRIAL REGISTRATION: The protocol for this review was recorded in the International Prospective Register of Systematic Reviews (PROSPERO) under registration number CRD42023441829.

Incremental Ramp Load Protocol to Assess Inspiratory Muscle Endurance in Healthy Individuals: Comparison with Incremental Step Loading Protocol.

INTRODUCTION: Protocols for obtaíníng the maxímum threshold pressure have been applied wíth límited precision to evaluate ínspiratory muscle endurance. In thís sense, new protocols are needed to allow more relíable measurements. The purpose of the present study was to compare a new incremental ramp load protocol for the evaluation of ínspíratory muscle endurance wíth the most used protocol in healthy indíviduals. METHODS: This was a prospective cross-sectional study carried out ín a síngle center. Nínety-two healthy indíviduals (43 men [22 ± 3 years] and 49 women [22 ± 3 years]) were randomly allocated to perform: (i) íncremental ramp load protocol and (íí) íncremental step loadíng protocol. The sustained pressure threshold (or maximum threshold pressure), maximum threshold pressure/dynamic strength índex ratío, time untíl task faílure, as well as dífference between the mean heart rate of the last five mínutes of baselíne and the peak heart rate of the last 30 seconds of each protocol were measured. RESULTS: Incremental ramp load protocol wíth small íncreases in the load and starting from mínímum values of strength index was able to evaluate the inspiratory muscle endurance through the maxímum threshold pressure of healthy indívíduals. CONCLUSION: The present study suggests that the íncremental ramp load protocol is able to measure maximum threshold pressure in a more thorough way, wíth less progression and greater accuracy in the load stratification compared to the límited incremental step loading protocol and with a safe and expected cardiovascular response in healthy individuals.

Comparative analysis of health-related fitness in patients with acute versus chronic Chagas disease. / Análisis comparativo del estado físico relacionado con la salud en pacientes con enfermedad aguda versus crónica de Chagas

INTRODUCTION: Although Chagas disease causes high levels of morbidity, the muscle function and tolerance to physical activity in Chagas disease patients are still not completely understood. OBJECTIVE: To compare health-related fitness of patient groups with acute Chagas disease versus chronic Chagas disease. MATERIALS AND METHODS: We conducted a cross-sectional study involving 18 patients. The data were obtained from patient´s records, and functional capacity was measured with the sixminute walk test, the peripheral muscle strength with handgrip strength, and respiratory muscle strength using the maximum inspiratory pressure and the maximum expiratory pressure. RESULTS: The 18 patients were divided in two groups: acute Chagas disease (n=9) and chronic Chagas disease (n=9). The distance walked in the six-minute walk test was lower than the predicted distance walked in both groups (p < 0.0001). The maximum expiratory pressure was lower than the predicted one (p = 0.005), and statistically significant for chronic Chagas disease patients (p = 0.02). Heart rate increased faster in the chronic Chagas disease group within the first two minutes of the six-minute walk test (p = 0.04). The sixminute walk test in the acute Chagas disease group presented a strong correlation with peripheral muscle strength (p = 0.012) and maximum inspiratory pressure (p = 0.0142), while in the chronic Chagas disease group, only peripheral muscle strength and maximum inspiratory pressure were correlated (p = 0.0259). CONCLUSION: The results suggest lowered functional capacity and reduced respiratory and peripheral muscle strength in patients with Chagas disease, although no differences were observed between groups. The early increase in heart rate during exercise in the chronic Chagas disease group implies a greater myocardial overload.

Introducción. Aunque la enfermedad de Chagas causa gran morbilidad, la función muscular y la tolerancia a la actividad física de estos pacientes aún no se comprenden por completo. Objetivos. Comparar el estado físico relacionado con la salud de pacientes con enfermedad de Chagas aguda versus crónica de Chagas. Materiales y métodos. Se hizo un estudio transversal que incluyó 18 pacientes. La información se obtuvo de los registros de los pacientes. La capacidad funcional se evaluó con la prueba de la caminata de seis minutos, se determinó la fuerza de prensión manual para evaluar los músculos periféricos y se estableció la fuerza de los músculos respiratorios mediante presión inspiratoria máxima y la presión espiratoria máxima. Resultados. Se evaluaron 18 pacientes, nueve con enfermedad de Chagas aguda y nueve con enfermedad de Chagas crónica. La distancia recorrida en la prueba de caminata de seis minutos fue menor que la distancia recorrida predicha en ambos grupos (p < 0,0001). La presión espiratoria máxima fue más baja de lo previsto (forma aguda: p = 0,005; forma crónica: p = 0,02). La frecuencia cardíaca aumentó más rápido en el grupo con enfermedad de Chagas crónica dentro de los primeros dos minutos de la caminata (p = 0,04). La distancia recorrida en el grupo con la forma aguda se correlacionó con la fuerza de prensión manual (p = 0,01) y la presión inspiratoria máxima (p = 0,01). En el grupo con la enfermedad crónica, solo hubo correlación entre la fuerza de presión manual y la presión inspiratoria máxima (p = 0,02). Conclusiones. Los resultados sugirieren disminución de la capacidad funcional y de la fuerza muscular respiratoria y periférica, aunque sin diferencias entre ambos grupos. El aumento de la frecuencia cardiaca en el grupo con enfermedad de Chagas crónica sugiere una mayor sobrecarga miocárdica.

Correlation of cervical-inspiratory-muscle electromyography and oxygen uptake during treadmill walking.

For measurements of exercise intensity, an individual's oxygen uptake (V̇O2) is measured with an exhaled gas analyzer that involves a mask, but exercise coaching would benefit if an individual's V̇O2 could be estimated with more easily obtained predictors. We investigated the predictability of V̇O2 by electromyography (EMG) of the neck inspiratory muscles. We analyzed the EMG results of the sternocleidomastoid (EMGst) and scalene (EMGsc) muscles of 14 healthy adults who performed a treadmill exercise load test. Their V̇O2, inspiratory flow rate, and heart rate were simultaneously recorded during the exercise. The exercise load test was performed twice at a ≥2-day interval. The first visit was an incremental exercise test, and the second was a repeated two-load exercise test at levels below and above the participant's ventilatory threshold (VT) as determined in the first test. We observed that the integrated EMG values for each exercise load showed partially significant positive correlations with the EMGst and EMGsc. However, the cervical inspiratory muscle EMGs did not show as high a correlation as the minute ventilation. These results indicate that (i) EMG of the cervical inspiratory muscles could be used to estimate V̇O2, but (ii) these EMG parameters alone should be considered insufficient for estimating V̇O2.

Association of IGF-1 and IGF-2 genotypes with respiratory muscle strength in individuals with COPD: A cross-sectional study.

Introduction: Chronic obstructive pulmonary disease is a systemic disease characterized not only by respiratory symptoms but also by physical deconditioning and muscle weakness. One prominent manifestation of this disease is the decline in respiratory muscle strength. Previous studies have linked the genotypes of insulin-like growth factor 1 and 2 (IGF-1 and IGF-2) to muscle weakness in other populations without this disease. However, there is a notable knowledge gap regarding the biological mechanisms underlying respiratory muscle weakness, particularly the role of IGF-1 and IGF-2 genotypes in this pulmonary disease. Therefore, this study aimed to investigate, for the first time, the association between IGF-1 and IGF-2 genotypes with respiratory muscle strength in individuals with chronic obstructive pulmonary disease. In addition, we analyzed the relationship between oxidative stress, chronic inflammation, and vitamin D with respiratory muscle strength. Methods: A cross sectional study with 61 individuals with chronic obstructive pulmonary disease. Polymerase chain reaction of gene polymorphisms IGF-1 (rs35767) and IGF-2 (rs3213221) was analyzed. Other variables, related to oxidative stress, inflammation and Vitamin D were dosed from peripheral blood. Maximal inspiratory and expiratory pressure were measured. Results: The genetic polymorphisms were associated with respiratory muscle strength ( 3.0 and 3.5; = 0.57). Specific genotypes of IGF-1 and IGF-2 presented lower maximal inspiratory and expiratory pressure (<0.05 for all). Oxidative stress, inflammatory biomarkers, and vitamin D were not associated with respiratory muscle strength. Conclusion: The polymorphisms of IGF-1 and IGF-2 displayed stronger correlations with respiratory muscle strength compared to blood biomarkers in patients with chronic obstructive pulmonary disease. Specific genotypes of IGF-1 and IGF-2 were associated with reduced respiratory muscle strength in this population.

Introducción: La enfermedad pulmonar obstructiva crónica es una enfermedad sistémica caracterizada no solo por síntomas respiratorios, sino también por el deterioro físico y la debilidad muscular. Una manifestación destacada de esta enfermedad es el declive en la fuerza de los músculos respiratorios. Estudios previos han vinculado los genotipos de factor de crecimiento insulínico 1 y 2 (IGF-1 e IGF-2) con la debilidad muscular en poblaciones sin esta enfermedad. Sin embargo, existe un vacío de conocimiento con respecto a los mecanismos biológicos subyacentes a la debilidad de los músculos respiratorios, en particular el papel de los genotipos IGF-1 e IGF-2 en esta enfermedad pulmonar. Por lo tanto, este estudio tuvo como objetivo investigar, por primera vez, la asociación de los genotipos IGF-1 e IGF-2 con la fuerza de los músculos respiratorios en individuos con enfermedad pulmonar obstructiva crónica. Además, analizamos la relación entre el estrés oxidativo, la inflamación crónica y la vitamina D con la fuerza de los músculos respiratorios. Métodos: Un estudio transversal con 61 individuos con enfermedad pulmonar obstructiva crónica. Se analizó la reacción en cadena de la polimerasa de los polimorfismos genéticos IGF-1 (rs35767) e IGF-2 (rs3213221). Otras variables relacionadas con el estrés oxidativo, la inflamación y la vitamina D se dosificaron a partir de muestras de sangre periférica. Se midieron las presiones inspiratorias y espiratorias máximas. Resultados: Los polimorfismos genéticos están asociados con la fuerza de los músculos respiratorios (F: 3.0 y 3.5; R2= 0.57). Genotipos específicos de IGF-1 e IGF-2 presentaron bajos valores en las presiones inspiratorias y espiratorias (p<0.05 en todos los casos). El estrés oxidativo, los biomarcadores inflamatorios y la vitamina D no se asociaron con la fuerza de los músculos respiratorios. Conclusión: Los polimorfismos de IGF-1 e IGF-2 mostraron correlaciones más sólidas con la fuerza de los músculos respiratorios en pacientes con enfermedad pulmonar obstructiva crónica en comparación con los biomarcadores sanguíneos. Genotipos específicos de IGF-1 e IGF-2 se asociaron con una disminución de la fuerza de los músculos respiratorios en esta población.

Assessment of maximal inspiratory and expiratory pressures in skeletal Class II patients with different growth patterns.

OBJECTIVES: To evaluate maximal inspiratory (MIP) and expiratory (MEP) pressures, which are reflective of respiratory muscle strength, in skeletal Class II patients with different growth patterns (horizontal, average, and vertical) and to correlate those with airway dimension. MATERIALS AND METHODS: Patients with a Class II skeletal base seeking orthodontic treatment were assigned to the following groups: average, horizontal, and vertical growth pattern. The control group (n = 14) comprised patients with a Class I skeletal base and average growth pattern. Airway dimensions were obtained using cone-beam computed tomography scans, and a spirometer with a pressure transducer was used for assessment of MIP and MEP. Routine spirometry for assessment of lung function was also performed. RESULTS: No significant differences were found in maximal inspiratory and expiratory pressures for the study groups in comparison with the control group. Class I patients had significantly greater oropharyngeal and nasopharyngeal airway volumes compared with the study groups. No significant difference in minimal cross-section area of the airway was observed among groups. A weak positive correlation between maximal inspiratory pressure and airway volume was observed. CONCLUSIONS: Although Class I patients displayed significantly greater oropharyngeal and nasopharyngeal airway volumes, there was no significant difference in respiratory muscle strength or airway function between Class II patients with different growth patterns and the Class I control group. The findings underscore the significance of exploring factors beyond craniofacial growth patterns that may contribute to sleep-related breathing disorders.