Maximal values of sniff nasal inspiratory pressure in healthy subjects

A cross-sectional study in 18 patients with typical and mild forms of nemaline myopathy in the Netherlands

Nemaline myopathy (NM) is a congenital myopathy with generalised muscle weakness, most pronounced in neck flexor, bulbar and respiratory muscles. The aim of this cross-sectional study was to assess the Dutch NM patient cohort. We assessed medical history, physical examination, quality of life (QoL), fatigue severity, motor function (MFM), and respiratory muscle function. We included 18 of the 28 identified patients (13 females (11-67 years old); five males (31-74 years old)) with typical or mild NM and eight different genotypes. Nine patients (50 %) used a wheelchair, eight patients (44 %) used mechanical ventilation, and four patients (22 %) were on tube feeding. Spinal deformities were found in 14 patients (78 %). The median Medical Research Council (MRC) sum score was 38/60 [interquartile range 32-51] in typical and 48/60 [44-50] in mild NM. The experienced QoL was lower and fatigue severity was higher than reference values of the healthy population. The total MFM score was 55 % [49-94] in typical and 88 % [72-93] in mild NM. Most of the patients who performed spirometry had a restrictive lung function pattern (11/15). This identification and characterisation of the Dutch NM patient cohort is important for international collaboration and can guide the design of future clinical trials.

Potential Diaphragm Muscle Weakness-related Dyspnea Persists 2 Years after COVID-19 and Could Be Improved by Inspiratory Muscle Training: Results of an Observational and an Interventional Clinical Trial

Rationale: Diaphragm muscle weakness might underlie persistent exertional dyspnea, despite normal lung and cardiac function in individuals who were previously hospitalized for acute coronavirus disease (COVID-19) illness. Objectives: The authors sought, first, to determine the persistence and pathophysiological nature of diaphragm muscle weakness and its association with exertional dyspnea 2 years after hospitalization for COVID-19 and, second, to investigate the impact of inspiratory muscle training (IMT) on diaphragm and inspiratory muscle weakness and exertional dyspnea in individuals with long COVID. Methods: Approximately 2 years after hospitalization for COVID-19, 30 individuals (11 women, 19 men; median age, 58 years; interquartile range [IQR] = 51-63) underwent comprehensive (invasive) respiratory muscle assessment and evaluation of dyspnea. Eighteen with persistent diaphragm muscle weakness and exertional dyspnea were randomized to 6 weeks of IMT or sham training; assessments were repeated immediately after and 6 weeks after IMT completion. The primary endpoint was change in inspiratory muscle fatiguability immediately after IMT. Measurements and Main Results: At a median of 31 months (IQR = 23-32) after hospitalization, 21 of 30 individuals reported relevant persistent exertional dyspnea. Diaphragm muscle weakness on exertion and reduced diaphragm cortical activation were potentially related to exertional dyspnea. Compared with sham control, IMT improved diaphragm and inspiratory muscle function (sniff transdiaphragmatic pressure, 83 cm H2O [IQR = 75-91] vs. 100 cm H2O [IQR = 81-113], P = 0.02), inspiratory muscle fatiguability (time to task failure, 365 s [IQR = 284-701] vs. 983 s [IQR = 551-1,494], P = 0.05), diaphragm voluntary activation index (79% [IQR = 63-92] vs. 89% [IQR = 75-94], P = 0.03), and dyspnea (Borg score, 7 [IQR = 5.5-8] vs. 6 [IQR = 4-7], P = 0.03). Improvements persisted for 6 weeks after IMT completion. Conclusions: To the best of the authors' knowledge, this study is the first to identify a potential treatment for persisting exertional dyspnea in long COVID and provide a possible pathophysiological explanation for the treatment benefit. Clinical trial registered with www.clinicaltrials.gov (NCT04854863, NCT05582642).

2024 SIAC guidelines on cardiorespiratory rehabilitation in pediatric patients with congenital heart disease

The 2024 Interamerican Society of Cardiology (SIAC) guidelines on cardiorespiratory rehabilitation (CRR) in pediatric patients with congenital heart disease aim to gather and evaluate all relevant evidence available on the topic to unify criteria and promote the implementation of CRR programs in this population in Latin America and other parts of the world. Currently, there is no unified CRR model for the pediatric population. Consequently, our goal was to create these CRR guidelines adapted to the characteristics of congenital heart disease and the physiology of this population, as well as to the realities of Latin America. These guidelines are designed to serve as a support for health care workers involved in the care of this patient group who wish to implement a CRR program in their workplace. The guidelines include an easily reproducible program model that can be implemented in any center. The members of this Task Force were selected by the SIAC on behalf of health care workers dedicated to the care of pediatric patients with congenital heart disease. To draft the document, the selected experts performed a thorough review of the published evidence.

Tension Pneumocephalus Secondary to Positive Pressure Ventilation Following Endoscopic Endonasal Skull Base Surgery: Three-Year Follow-Up After Implementation of an Institutional Protocol

BACKGROUND

Tension pneumocephalus (PMC) is a rare and feared complication following the endonasal endoscopic approach (EEA) to skull base procedures. This is a neurosurgical emergency that requires urgent decompression to avoid catastrophic neurologic damage or death. An avoidable cause is the application of positive pressure ventilation (PPV) in EEA patients for postoperative hypoxia. Our institution implemented a hospital-wide protocol in response to this to identify and manage at-risk patients; this paper aims to identify if this protocol was effective in lowering the rates of tension PMC secondary to PPV.

RESULTS

In the 3 years following the implementation of the protocol, 110 patients underwent EEAs, from which 1 case of tension PMC (found to be not secondary to PPV) was identified. This is compared with 2 cases of tension PMC secondary to PPV over the preceding 5 years, out of 406 EEA patients. This constitutes a quantifiable reduction in PPV-related tension PMC in both standard and extended approach EEAs, signifying the effective uptake of the protocol.

CONCLUSIONS

We found no cases of tension PMC after PPV following EEA skull base surgery in our institution since the implementation of an institution-wide guideline. This underscores the utility of our simple and cost-effective preventative protocol in reducing the overall rates of tension PMC following the inadvertent postoperative application of PPV. Further research is needed to study the comparative risks and benefits of PPV in the post-EEA patient and thus inform future iterations of the protocol.

Spectrum of sleep-disordered breathing and quality of sleep in adolescent and adult patients with spinal muscular atrophy

Sleep-disordered breathing is common among children with spinal muscular atrophy, but has been hardly studied among adult subjects. Little is known about sleep quality in spinal muscular atrophy. The aims of this study were to evaluate occurrence and characteristics of sleep-disordered breathing and subjective sleep quality among adolescent and adult patients with spinal muscular atrophy type 2 or 3. Twenty patients aged 33.9 ± 15.2 years were studied. They underwent nocturnal cardiorespiratory monitoring, lung and muscular function evaluation, and were administered the Pittsburgh Sleep Quality Index questionnaire. Nineteen patients showed sleep-disordered breathing, with obstructive events in seven subjects and non-obstructive events in the remaining 12. In the latter group, 10 patients showed pseudo-obstructive hypopneas. Patients with non-obstructive sleep-disordered breathing were younger (p = 0.042), had a lower body mass index (p = 0.0001), were more often affected by spinal muscular atrophy type 2 (p = 0.001), and showed worse impairment of respiratory function than patients with obstructive sleep-disordered breathing. Ten patients were classified as poor sleepers and 10 patients good sleepers. In the whole sample, sniff nasal inspiratory pressure proved to be the only independent predictor of sleep quality (p = 0.009). In conclusion, sleep-disordered breathing is common even among adult patients with spinal muscular atrophy type 2 and 3, and may show either obstructive or different types on non-obstructive features. A worse respiratory muscle function is associated to non-obstructive sleep-disordered breathing and poorer sleep quality. Sleep quality should receive greater attention especially in patients with spinal muscular atrophy type 2, who have a poorer respiratory muscle function, as it could affect their quality of life.

Responsiveness of respiratory function in Parkinson's Disease to an integrative exercise programme: A prospective cohort study

INTRODUCTION

Respiratory disorders are the most common cause of death in Parkinson's Disease (PD). Conflicting data exist on the aetiology of respiratory dysfunction in PD and few studies examine the effects of exercise-based interventions on respiratory measures. This study was conducted to better understand respiratory dysfunction in PD and to identify measures of dysfunction responsive to an integrative exercise programme.

OBJECTIVES

The objectives were to compare baseline respiratory measures with matched, published population norms and to examine immediate and longer-term effects of a 12-week integrated exercise programme on these measures.

DESIGN

Twenty-three people with mild PD (median Hoehn & Yahr = 2) self-selected to participate in this exploratory prospective cohort study. Evaluation of participants occurred at three time points: at baseline; following the 12-week exercise programme and at 4-month follow-up.

OUTCOME MEASURES

Outcome measures included: Forced Vital Capacity (FVC), Forced Expiratory Volume in 1 second (FEV1), FEV1/FVC ratio, Peak Expiratory Flow (PEF), Inspiratory Muscle Strength (MIP), Expiratory Muscle Strength (MEP), Peak Cough Flow (PCF), and Cardiovascular Fitness measures of estimated VO2 max and 6-Minute Walk Test (6MWT).

RESULTS

Compared to published norms, participants had impaired cough, reduced respiratory muscle strength, FEV, FVC, PEF and cardiovascular fitness. Post exercise intervention, statistically significant improvements were noted in MEP, cardiovascular fitness, and PEF. However only gains in PEF were maintained at 4-month follow-up.

CONCLUSIONS

Significant respiratory dysfunction exists, even in the early stages of PD. Metrics of respiratory muscle strength, peak expiratory flow and cardiovascular fitness appear responsive to an integrative exercise programme.

Sniff and reverse-sniff nasal respiratory pressures after exacerbation of chronic obstructive pulmonary disease: A single-center prospective study

BACKGROUND

and objective: This study examined the validity of sniff nasal inspiratory (SNIP) and reverse-sniff nasal expiratory pressures (RSNEP) for estimating respiratory muscle strength and for predicting poor life expectancy following exacerbation in patients with chronic obstructive pulmonary disease (COPD).

METHODS

This prospective study included patients who were admitted for COPD exacerbation and underwent rehabilitation. At hospital discharge, SNIP, RSNEP, and maximum mouth inspiratory (MIP) and expiratory pressures (MEP) were measured, and the body mass index, degree of airflow obstruction, dyspnea, and exercise capacity (BODE) index was calculated by evaluating body mass index, forced expiratory volume in 1 s (FEV1), the Modified Medical Research Council Dyspnea Scale, and 6-min walk distance.

RESULTS

Data from 43 patients (mean age 76.8 years, FEV1 42.8 % predicted) were analyzed. SNIP and RSNEP were moderately correlated with MIP and MEP, respectively. Bland-Altman plot means of SNIP (48.3 ± 17.5) and RSNEP (44.7 ± 23.8 cmH2O) were lower than those of MIP (54.8 ± 19.9) and MEP (76.4 ± 31.2 cmH2O), respectively, and the SNIP-MIP and RSNEP-MEP 95 % limits of agreement were wide. Logistic regression showed that SNIP and RSNEP were significantly associated with BODE score ≥7 (poor life expectancy), and predictive accuracy was 81.4 % when combining SNIP ≤49 and RSNEP ≤42 cmH2O.

CONCLUSION

After exacerbation in patients with COPD, SNIP and RSNEP are useful indicators that complement MIP and MEP. Furthermore, a combined SNIP and RSNEP test may be beneficial in predicting poor life expectancy.

A Randomized Controlled Clinical Trial of Lung Volume Recruitment in Adults with Neuromuscular Disease

Rationale: Clinical care guidelines advise that lung volume recruitment (LVR) be performed routinely by people with neuromuscular disease (NMD) to maintain lung and chest wall flexibility and slow lung function decline. However, the evidence base is limited, and no randomized controlled trials of regular LVR in adults have been published. Objectives: To evaluate the effect of regular LVR on respiratory function and quality of life in adults with NMD. Methods: A randomized controlled trial with assessor blinding was conducted between September 2015 and May 2019. People (>14 years old) with NMD and vital capacity <80% predicted were eligible, stratified by disease subgroup (amyotrophic lateral sclerosis/motor neuron disease or other NMDs), and randomized to 3 months of twice-daily LVR or breathing exercises. The primary outcome was change in maximum insufflation capacity (MIC) from baseline to 3 months, analyzed using a linear mixed model approach. Results: Seventy-six participants (47% woman; median age, 57 [31-68] years; mean baseline vital capacity, 40 ± 18% predicted) were randomized (LVR, n = 37). Seventy-three participants completed the study. There was a statistically significant difference in MIC between groups (linear model interaction effect P = 0.002, observed mean difference, 0.19 [0.00-0.39] L). MIC increased by 0.13 (0.01-0.25) L in the LVR group, predominantly within the first month. No interaction or treatment effects were observed in secondary outcomes of lung volumes, respiratory system compliance, and quality of life. No adverse events were reported. Conclusions: Regular LVR increased MIC in a sample of LVR-naive participants with NMD. We found no direct evidence that regular LVR modifies respiratory mechanics or slows the rate of lung volume decline. The implications of increasing MIC are unclear, and the change in MIC may represent practice. Prospective long-term clinical cohorts with comprehensive follow-up, objective LVR use, and clinically meaningful outcome data are needed. Clinical trial registered with anzctr.org.au (ACTRN12615000565549).

Monitoring and Management of Respiratory Function in Pompe Disease: Current Perspectives

Pompe disease (PD) is a neuromuscular disorder caused by a deficiency of acid alpha-glucosidase (GAA) - a lysosomal enzyme responsible for hydrolyzing glycogen. GAA deficiency leads to accumulation of glycogen in lysosomes, causing cellular disruption. The severity of PD is directly related to the extent of GAA deficiency - if no or minimal GAA is produced, symptoms are severe and manifest in infancy, known as infantile onset PD (IOPD). If left untreated, infants with IOPD experience muscle hypotonia and cardio-respiratory failure leading to significant morbidity and mortality in the first year of life. In contrast, late-onset PD (LOPD) patients have more GAA activity and present later in life, but also have significant respiratory function decline. Despite FDA-approved enzyme replacement therapy, respiratory insufficiency remains a major cause of morbidity and mortality, emphasizing the importance of early detection and management of respiratory complications. These complications include impaired cough and airway clearance, respiratory muscle weakness, sleep-related breathing issues, and pulmonary infections. This review aims to provide an overview of the respiratory pathology, monitoring, and management of PD patients. In addition, we discuss the impact of novel approaches and therapies on respiratory function in PD.

Respiratory Muscle Function in Older Adults with Chronic Respiratory Diseases after Pulmonary Rehabilitation in Subterranean Salt Chambers

Training the respiratory muscles is a crucial aspect of pulmonary rehabilitation. The purpose of this study was to assess the function of respiratory muscles in older adults both before and after a period of pulmonary rehabilitation and treatment stay within the underground chambers of a salt mine. A total of 50 patients aged 65 years and older with chronic respiratory conditions was enrolled in the study. These participants underwent a 3-week subterranean pulmonary rehabilitation (PR) program in the "Wieliczka" Salt Mine. Levels of sniff nasal inspiratory pressure (SNIP), maximum inspiratory pressure (MIP), and maximum expiratory pressure (MEP) were measured using the MicroRPM both before and after the outpatient PR program conducted 135 m underground. A total of 44 patients with a mean age of 68.8 ± 2.9 years who completed the PR program and tests were included in the analysis. The average changes in the parameters of pulmonary function before and after the PR were: MIP 8.8 cmH2O, MEP 7.1 cmH2O, and SNIP 11.2 cmH2O (for p < 0.05). For patients older than 70 years, beneficial changes were only observed for MEP, which increased by 9.3 cmH2O (for p < 0.05). Speleotherapy combined with pulmonary rehabilitation improves respiratory muscle function in older adults with chronic respiratory diseases, mainly in terms of MEP. Therefore, a greater emphasis on inspiratory muscle training in the rehabilitation program should be considered.

Respiratory Muscle Function and Exercise Performance in Adult Patients with Fontan Circulation

At rest, a good Fontan circulation can provide a normal cardiac output (CO). However, as a consequence of its unique hemodynamic nature, the limitations of the Fontan circuit are exposed during exercise. We aimed to provide a comprehensive assessment of the pathophysiology of exercise in adult Fontan patients (FPs) and identify factors limiting their functional capacity (FC). In a single-center study conducted in 37 FPs aged ≥16 years and 19 healthy-controls (HCs) who underwent CPET on a cycle ergometer in February and March 2022, the mean peakVO₂ was 21 ± 5.4 mL/kg/min, which was 55% of the predicted value. Morphologically, the left single ventricle showed a higher peakVO₂% predicted value (57.4 ± 14.4% vs. 43.4 ± 8.1%, p = 0.045). The factors associated with low peakVO₂ values were an early flattened or descending O₂ pulse at maximal exertion (52 ± 14% vs. 62 ± 12.5, p = 0.04 and 47.6 ± 9% vs. 60 ± 14, p = 0.018, respectively) and chronotropic insufficiency (53 ± 12% vs. 69.8 ± 20%, p = 0.008). The OUES was found to be a useful parameter to assess the FC in FPs in maximal and submaximal exercise testing. A strong positive correlation was observed between the %OUES and peakVO₂%predicted (r = 0.726, p > 0.001). The lung function was impaired in the FPs, mostly with a mild restrictive pattern (56.8%). The FPs showed lower inspiratory muscle strength compared to the HCs but it was not statistically associated with either the peakVO₂ or VE/VCO₂ slope. Regular intense physical activity improves one's FC. Although FPs have inspiratory muscle weakness, its impact on their FC is unclear. The peakVO₂% predicted grew progressively higher as the level of physical activity increased (low level 49.5 ± 14%, moderate level 55 ± 12%, intense level 69 ± 20%).

Optimization of sniff nasal inspiratory pressure (SNIP) measurement methodology in healthy subjects

BACKGROUND

Maximal inspiratory pressure (MIP) is currently the most commonly used measure for respiratory muscle strength (RMS) estimation, however, requires significant effort. Falsely low values are therefore common, especially in fatigue-prone subjects, such as neuromuscular disorder patients. In contrast, sniff nasal inspiratory pressure (SNIP) requires a short, sharp sniff; this is a natural manoeuvre, decreasing required effort. Consequently, it has been suggested that use of SNIP could confirm the accuracy of MIP measurements. However, no recent guidelines regarding the optimal method of SNIP measurement exist, and varied approaches have been described.

OBJECTIVES

We compared SNIP values from three conditions, namely with 30, 60 or 90 s time intervals between repeats, the right (SNIP_R) and left (SNIP_L) nostril, and the contralateral nostril occluded (SNIP_O) or non-occluded (SNIP_NO). Additionally, we determined the optimal number of repeats for accurate SNIP measurement.

METHOD

52 healthy subjects (23 males) were recruited for this study, of which a subset of 10 subjects (5 males) completed tests comparing the time interval between repeats. SNIP was measured from functional residual capacity via a probe in one nostril, while MIP was measured from residual volume.

RESULTS

There was no significant difference in SNIP depending on the interval between repeats (P = 0.98); subjects preferred the 30 s. SNIP_O was significantly higher than SNIP_NO (P < 0.00001) but SNIP_L and SNIP_R did not significantly differ (P =  0.60). There was an initial learning effect for the first SNIP test; SNIP did not decline during 80 repeats (P =  0.64).

CONCLUSIONS

We conclude that SNIP_O is a more reliable RMS indicator than SNIP_NO, as there is reduced risk of RMS underestimation. Allowing subjects to choose which nostril to use is appropriate, as this did not significantly affect SNIP, but may increase ease of performance. We suggest that twenty repeats is sufficient to overcome any learning effect and that fatigue is unlikely after this number of repeats. We believe these results are important in aiding the accurate collection of SNIP reference value data in the healthy population.

Assessment of the Function of Respiratory Muscles in Patients after COVID-19 Infection and Respiratory Rehabilitation

OBJECTIVES

The MIP (maximum inspiratory pressure) and MEP (maximum expiratory pressure) are sensitive indicators of respiratory muscle function. The aim of the study was to assess the function of respiratory muscles in patients after COVID-19 infection, before and after hospitalisation at the Pulmonary Rehabilitation Ward.

MATERIALS AND METHODS

The study was conducted on a group of 19 people with laboratory-confirmed COVID-19 infection, who, in the period from 1 February to 31 May 2021, were hospitalised at the Independent Public Pulmonary Hospital and underwent respiratory rehabilitation in hospital conditions. A statistical analysis was performed using the STATISTICA package, ver. 10. A respiratory pressure meter (RP Check) was used to measure muscle strength. Measurements were performed twice on each patient-before admission and after hospitalisation in the Pulmonary Rehabilitation Ward.

RESULTS

We show that conducting pulmonary rehabilitation contributes to the increase in MIP and MEP, which are associated with increased strength of the inspiratory and expiratory muscles. The average value of MIP increased by 11.95 cmH₂O and MEP by 26.16 cmH₂O. The improvement was visible in both female and male patients.

CONCLUSIONS

Pulmonary rehabilitation contributes to the improvement of respiratory muscle function indicators among patients after COVID-19 infection. Assessment of the MIP and MEP indices is a simple and quick way to reliably assess the function of the respiratory muscles.

Validation of the Single Breath Count Test for Assessment of Inspiratory Muscle Strength in Healthy Subjects and People with Neuromuscular Disorders

OBJECTIVE

This study aimed to validate the single breath count test (SBCT) against volitional measures of respiratory muscle function in healthy subjects and people with neuromuscular disorders (NMD; n = 100 per group).

METHODS

Testing comprised upright and supine SBCT, forced vital capacity (FVC), maximum inspiratory pressure (MIP), and sniff nasal inspiratory pressure (SNIP). Predictability of FVC by SBCT was assessed using logarithmic regression analysis. Receiver operating characteristics curves were used to identify SBCT thresholds for lung restriction (FVC < 80% predicted), inspiratory muscle weakness (MIP < 60 cmH2O), and indication for non-invasive ventilation (NIV) in NMD patients.

RESULTS

In both groups, SBCT showed moderate correlation with FVC. In patients, SBCT values were also correlated with MIP and SNIP. Strength of correlations was similar with supine and upright SBCT which accounted for 23.7% of FVC variance in healthy individuals (44.5% in patients). Predictive thresholds of upright SBCT were < 27 for MIP < 60 cmH2O (sensitivity 0.61/specificity 0.86), <39 for NIV indication (0.92/0.46), and <41 for FVC < 80% predicted (0.89/0.62).

CONCLUSION

The SBCT is positively correlated with spirometry. It predicts both lung restriction and NIV indication in NMD patients. The SBCT allows for remote monitoring and may substitute for spirometry/manometry if appropriate devices are unavailable.

Inspiratory Muscle Training in Nemaline Myopathy

BACKGROUND

Respiratory muscle weakness is a common feature in nemaline myopathy. Inspiratory muscle training (IMT) is an intervention that aims to improve inspiratory muscle strength.

OBJECTIVE

The aim of this controlled before-and-after pilot study was to investigate if IMT improves respiratory muscle strength in patients with nemaline myopathy.

METHODS

Nine patients (7 females; 2 males, age 36.6±20.5 years) with respiratory muscle weakness and different clinical phenotypes and genotypes were included. Patients performed eight weeks of sham IMT followed by eight weeks of active threshold IMT. The patients trained twice a day five days a week for 15 minutes at home. The intensity was constant during the training after a gradual increase to 30% of maximal inspiratory pressure (MIP).

RESULTS

Active IMT significantly improved MIP from 43±15.9 to 47±16.6 cmH2O (p = 0.019). The effect size was 1.22. There was no significant effect of sham IMT. Sniff nasal inspiratory pressure, maximal expiratory pressure, spirometry, and diaphragm thickness and thickening showed no significant improvements.

CONCLUSIONS

This pilot study shows that threshold IMT is feasible in patients with nemaline myopathy and improves inspiratory muscle strength. Our findings provide valuable preliminary data for the design of a larger, more comprehensive trial.

Rapidly and slowly progressive neuromuscular disease: differences in pulmonary function, respiratory tract infections and response to lung volume recruitment therapy (LVR)

INTRODUCTION

Reduced lung volumes are a hallmark of respiratory muscle weakness in neuromuscular disease (NMD). Low respiratory system compliance (C_rs) may contribute to restriction and be amenable to lung volume recruitment (LVR) therapy. This study evaluated respiratory function and the immediate impact of LVR in rapidly progressive compared to slowly progressive NMD.

METHODS

We compared vital capacity (VC), static lung volumes, maximal inspiratory and expiratory pressures (MIP, MEP), C_rs and peak cough flow (PCF) in 80 adult participants with motor neuron disease ('MND'=27) and more slowly progressive NMDs ('other NMD'=53), pre and post a single session of LVR. Relationships between respiratory markers and a history of respiratory tract infections (RTI) were examined.

RESULTS

Participants with other NMD had lower lung volumes and C_rs but similar reduction in respiratory muscle strength compared with participants with MND (VC=1.30±0.77 vs 2.12±0.75 L, p<0.001; C_rs=0.0331±0.0245 vs 0.0473±0.0241 L/cmH₂O, p=0.024; MIP=39.8±21.3 vs 37.8±19.5 cmH₂O). More participants with other NMD reported an RTI in the previous year (53% vs 22%, p=0.01). The likelihood of having a prior RTI was associated with baseline VC (%predicted) (OR=1.03 (95% CI 1.00 to 1.06), p=0.029). Published thresholds (VC<1.1 L or PCF<270 L/min) were, however, not associated with prior RTI.A single session of LVR improved C_rs (mean (95% CI) increase = 0.0038 (0.0001 to 0.0075) L/cmH₂O, p=0.047) but not VC.

CONCLUSION

These findings corroborate the hypothesis that ventilatory restriction in NMD is related to weakness initially with respiratory system stiffness potentiating lung volume loss in slowly progressive disease. A single session of LVR can improve C_rs. A randomised controlled trial of regular LVR is needed to assess longer-term effects.

Respiratory muscle endurance training improves exercise performance but does not affect resting blood pressure and sleep in healthy active elderly

Purpose

Ageing is associated with increased blood pressure (BP), reduced sleep, decreased pulmonary function and exercise capacity. The main purpose of this study was to test whether respiratory muscle endurance training (RMET) improves these parameters.

Methods

Twenty-four active normotensive and prehypertensive participants (age: 65.8 years) were randomized and balanced to receive either RMET (N = 12) or placebo (PLA, N = 12). RMET consisted of 30 min of volitional normocapnic hyperpnea at 60% of maximal voluntary ventilation while PLA consisted of 1 inhalation day⁻¹ of a lactose powder. Both interventions were performed on 4–5 days week⁻¹ for 4–5 weeks. Before and after the intervention, resting BP, pulmonary function, time to exhaustion in an incremental respiratory muscle test (incRMET), an incremental treadmill test (IT) and in a constant-load treadmill test (CLT) at 80% of peak oxygen consumption, balance, sleep at home, and body composition were assessed. Data was analyzed with 2 × 2 mixed ANOVAs.

Results

Compared to PLA, there was no change in resting BP (independent of initial resting BP), pulmonary function, IT performance, sleep, body composition or balance (all p > 0.05). Performance significantly increased in the incRMET (+ 6.3 min) and the CLT (+ 3.2 min), resulting in significant interaction effects (p < 0.05).

Conclusion

In the elderly population, RMET might be used to improve respiratory and whole body endurance performance either as an adjunct to physical exercise training or as a replacement thereof for people not being able to intensively exercise even if no change in BP or sleep may be expected.

Respiratory Muscle Strength in Healthy Indian Children of Age 7-17 Years: A Cross-Sectional Study

Purpose

As the values of respiratory muscle strength vary according to race, ethnicity, and geographical area, there is a wide-ranging difference among different populations. Thus, the available reference values may not have an application for use in the Indian paediatric population, creating a need for generating values which will be appropriate for the Indian paediatric context.

Materials and Methods

Assessment of respiratory muscle strength was carried out by assessing maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) and synthesising predictive formulas using anthropometric variables like height, gender and age, which will be suitable for Indian children.

Results

We calculated MIP and MEP of 320 (boys=160 and girls= 160) children in the age range of 7 years to 17 years of Mangaluru city, India. Results stated that mean MIP and MEP for boys were 72.5±32.8 cm H₂O and 73±33.2 cm H₂O, while for the girls it was 67±30.2 cm H₂O and 68±30.1 cm H₂O, respectively.

Conclusion

This study concluded that there is a difference in respiratory pressure values of Indian children with respect to those of other countries. Age, gender, height and BMI have a significant role in determining respiratory muscle strength. Boys demonstrated higher MIP and MEP. As age, height, weight and BMI increases, so does MIP and MEP.

Thoracoabdominal asynchrony and paradoxical motion in Duchenne muscular dystrophy and healthy subjects during cough: A case control study

OBJECTIVE

To assess thoracoabdominal asynchrony (TAA) and inspiratory paradoxical motion at different positionings in subjects with Duchenne muscular dystrophy (DMD) versus healthy subjects during quiet spontaneous breathing (QB) and cough.

METHODS

This is a case control study with a matched-pair design. We assessed 14 DMD subjects and 12 controls using optoelectronic plethysmography (OEP) during QB and spontaneous cough in 3 positions: supine, supine with headrest raised at 45°, and sitting with back support at 80°. The TAA was assessed using phase angle (θ) between upper (RCp) and lower rib cage (RCa) and abdomen (AB), as well as the percentage of inspiratory time the RCp (IP_RCp ), RCa (IP_RCa ), and AB (IP_AB ) moved in opposite directions.

RESULTS

During cough, DMD group showed higher RCp and RCa θ (p < .05), RCp and AB θ (p < .05) in supine and 45° positions, and higher RCp and Rca θ (p = .006) only in supine position compared with controls. Regarding the intragroup analysis, during cough, DMD group presented higher RCp and AB θ (p = .02) and RCa and AB θ (p = .002) in supine and higher RCa and AB θ (p = .002) in 45° position when compared to 80°. Receiver operating characteristic curve analyzes were able to discriminate TAA between controls and DMD in RCa supine position (area under the curve: 0.81, sensibility: 78.6% and specificity: 91.7%, p = .001).

CONCLUSION

Subjects with DMD yields TAA with insufficient deflation of chest wall compartments and rib cage distortion during cough, by noninvasive assessment.

ARTP statement on pulmonary function testing 2020

The Association for Respiratory Technology & Physiology (ARTP) last produced a statement on the performance of lung function testing in 1994. At that time the focus was on a practical statement for people working in lung function laboratories. Since that time there have been many technological advances and alterations to best practice in the measurement and interpretation of lung function assessments. In light of these advances an update was warranted. ARTP, therefore, have provided within this document, where available, the most up-to-date and evidence-based recommendations for the most common lung function assessments performed in laboratories across the UK. These recommendations set out the requirements and considerations that need to be made in terms of environmental and patient factors that may influence both the performance and interpretation of lung function tests. They also incorporate procedures to ensure quality assured diagnostic investigations that include those associated with equipment, the healthcare professional conducting the assessments and the results achieved by the subject. Each section aims to outline the common parameters provided for each investigation, a brief principle behind the measurements (where applicable), and suggested acceptability and reproducibility criteria.

Reliability of SNIP test and optimal number of maneuvers in 6-11 years healthy children

BACKGROUND AND PURPOSE

Sniff nasal inspiratory pressure (SNIP) is a voluntary inspiratory maneuver measured through a plug occluding one nostril. The investigation of the number of maneuvers necessary to reach the highest peak of SNIP in pediatric populations has been inconsistent. Thus, this study aimed to assess the reliability of SNIP in healthy children aged 6 to 11 years according to sex and age group, and to determine the optimal number of SNIP maneuvers for this age group.

METHODS

This cross-sectional study included healthy children with normal pulmonary function. We performed 12 to 20 SNIP maneuvers, with a 30 s rest between each maneuver. The reliability was tested using the intraclass correlation coefficient (ICC), standard error of measurement (SEM), minimal detectable change (MDC), and Bland-Altman analysis for agreement.

RESULTS

A total of 121 healthy children (62 girls [51%]) were included in this study. The ICC and corresponding confidence interval (CI) between the highest measure and the first reproducible maneuver were 0.752 (0.656-0.824), SEM = 10.37 cmH2O, and MDC = 28.74 cmH2O. For children aged 6 to 7 years, the ICC was 0.669 (0.427-0.822), SEM = 10.76 cmH2O and MDC = 29.82 cmH2O; for children aged 8 to 11 years, the ICC was 0.774 (0.662-0.852), SEM = 9.74 cmH2O, and MDC = 26.05 cmH2O. For girls, the ICC was 0.817 (0.706-0.889), SEM = 9.40 cmH2O and MDC = 26.05 cmH2O; for boys, the ICC was 0.671 (0.487-0.798), SEM = 11.51 cmH2O, and MDC = 31.90 cmH2O. Approximately 80% of the total sample reached the highest SNIP before the 10th maneuver.

CONCLUSIONS

SNIP demonstrated moderate reliability between the maneuvers in children aged 6 to 11 years; older children and girls reached the SNIP peak faster. Finally, results indicated that 12 maneuvers were sufficient for healthy children aged 6 to 11 years to achieve the highest SNIP peak.

Pulmonary function testing in COPD: looking beyond the curtain of FEV1

Chronic obstructive pulmonary disease (COPD) management remains challenging due to the high heterogeneity of clinical symptoms and the complex pathophysiological basis of the disease. Airflow limitation, diagnosed by spirometry, remains the cornerstone of the diagnosis. However, the calculation of the forced expiratory volume in the first second (FEV1) alone, has limitations in uncovering the underlying complexity of the disease. Incorporating additional pulmonary function tests (PFTs) in the everyday clinical evaluation of COPD patients, like resting volume, capacity and airway resistance measurements, diffusion capacity measurements, forced oscillation technique, field and cardiopulmonary exercise testing and muscle strength evaluation, may prove essential in tailoring medical management to meet the needs of such a heterogeneous patient population. We aimed to provide a comprehensive overview of the available PFTs, which can be incorporated into the primary care physician's practice to enhance the efficiency of COPD management.

Clinical Guidelines for Diagnosis and Treatment of Botulism, 2021

Botulism is a rare, neurotoxin-mediated, life-threatening disease characterized by flaccid descending paralysis that begins with cranial nerve palsies and might progress to extremity weakness and respiratory failure. Botulinum neurotoxin, which inhibits acetylcholine release at the neuromuscular junction, is produced by the anaerobic, gram-positive bacterium Clostridium botulinum and, rarely, by related species (C. baratii and C. butyricum). Exposure to the neurotoxin occurs through ingestion of toxin (foodborne botulism), bacterial colonization of a wound (wound botulism) or the intestines (infant botulism and adult intestinal colonization botulism), and high-concentration cosmetic or therapeutic injections of toxin (iatrogenic botulism). In addition, concerns have been raised about the possibility of a bioterrorism event involving toxin exposure through intentional contamination of food or drink or through aerosolization. Neurologic symptoms are similar regardless of exposure route. Treatment involves supportive care, intubation and mechanical ventilation when necessary, and administration of botulinum antitoxin. Certain neurological diseases (e.g., myasthenia gravis and Guillain-Barré syndrome) have signs and symptoms that overlap with botulism. Before the publication of these guidelines, no comprehensive clinical care guidelines existed for treating botulism. These evidence-based guidelines provide health care providers with recommended best practices for diagnosing, monitoring, and treating single cases or outbreaks of foodborne, wound, and inhalational botulism and were developed after a multiyear process involving several systematic reviews and expert input.

Natural history of Type 2 and 3 spinal muscular atrophy: 2-year NatHis-SMA study

Objective

To characterize the natural history of spinal muscular atrophy (SMA) over 24 months using innovative measures such as wearable devices, and to provide evidence for the sensitivity of these measures to determine their suitability as endpoints in clinical trials.

Methods

Patients with Type 2 and 3 SMA (N = 81) with varied functional abilities (sitters, nonsitters, nonambulant, and ambulant) who were not receiving disease‐modifying treatment were assessed over 24 months: motor function (Motor Function Measure [MFM]), upper limb strength (MyoGrip, MyoPinch), upper limb activity (ActiMyo^®), quantitative magnetic resonance imaging (fat fraction [FF_T2] mapping and contractile cross‐sectional area [C‐CSA]), pulmonary function (forced vital capacity [FVC], peak cough flow, maximum expiratory pressure, maximum inspiratory pressure, and sniff nasal inspiratory pressure), and survival of motor neuron (SMN) protein levels.

Results

MFM32 scores declined significantly over 24 months, but not 12 months. Changes in upper limb activity could be detected over 6 months and continued to decrease significantly over 12 months, but not 24 months. Upper limb strength decreased significantly over 12 and 24 months. FVC declined significantly over 12 months, but not 24 months. FF_T2 increased over 12 and 24 months, although not with statistical significance. A significant increase in C‐CSA was observed at 12 but not 24 months. Blood SMN protein levels were stable over 12 and 24 months.

Interpretation

These data demonstrate that the MFM32, MyoGrip, MyoPinch, and ActiMyo^® enable the detection of a significant decline in patients with Type 2 and 3 SMA over 12 or 24 months.

Measuring vital capacity in amyotrophic lateral sclerosis: Effects of interfaces and reproducibility

BACKGROUND

Deterioration of vital capacity (VC) in amyotrophic lateral sclerosis (ALS) signifies disease progression and indicates need for non-invasive ventilation. Weak facial muscles consequent to ALS, with resulting poor mouth seal, may interfere with the accuracy of VC measurements.

OBJECTIVES

To determine whether different interfaces affect VC measurements in ALS patients and whether the interface yielding the largest VC produces an even higher VC when re-measured after one week (learning effect). To explore the relationship between optimal interface VC and sniff nasal pressure (SNIP), a measurement of global inspiratory muscle strength.

METHODS

Thirty-five patients (17 bulbar and 18 spinal ALS) were studied. Three interfaces (rigid-cylindrical, flanged, oronasal mask) were tested. One week after the first visit, VC was recorded using the optimal interface. SNIP recordings were also obtained.

RESULTS

In the bulbar ALS group, median (interquartile range) VC with the flanged mouthpiece was 8.4% (3.9-15.5) larger than with the cylindrical mouthpiece (p < 0.001). VC values with oronasal mask were intermediate to VC with the other two interfaces. In spinal ALS, flanged mouthpiece VC was 4.6% (2.3-7.5) larger than with oronasal mask (p < 0.0006). The latter was 4.5% (0.6-5.2) smaller than with the cylindrical mouthpiece (p = 0.002). In both groups, VC during the second visit was greater than during the first visit (p < 0.025). SNIPs were logarithmically related to VC values recorded with the flanged mouthpiece.

CONCLUSION

A flanged mouthpiece yields the largest values of VC in patients with bulbar and spinal ALS.

Comparison between breath stacking technique associated with expiratory muscle training and breath stacking technique in amyotrophic lateral sclerosis patients: Protocol for randomized single blind trial

Introduction

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease affecting both upper and lower motor neurons, and lead to respiratory failure. Strategies are suggested to respiratory management in ALS patients, as the breath stacking and Expiratory muscle training (EMT), which have been used as aid to assist cough in neuromuscular disorders. However, the randomized controlled trials performed in ALS patients have not investigated the addiction of EMT together breath stacking in this population. This trial aims to determine if breath stacking plus EMT is more effective than breath stacking alone to decrease the decline rate on the inspiratory/expiratory muscle strength, FVC and voluntary PCF in ALS patients.

Methods

This parallel-group, assessor-blinded randomized controlled trial, powered for superiority, aims to assess pulmonary function, respiratory muscle strength, peak cough flow as primary outcomes. Forty-two participants are being recruited referral neuromuscular disease center at Brasilia, Brazil. Following baseline testing, participants are randomized using concealed allocation, to receive either: a) breath stacking technique alone or b) breath stacking technique plus EMT.

Conclusion

There is a lack of evidence regarding the benefit of EMT plus breath stacking in ALS patients. This trial will contribute to evidence currently being generated in national and international trials by implementing and evaluating a respiratory therapy program including two components not yet combined in previous research, for people with ALS involving longer-term follow-up of outcomes. This trial is ongoing and currently recruiting.

Trial registration

This trial was prospectively registered on the Clinical Trials Registry NCT04226144.

Maximal Static Respiratory and Sniff Pressures in Healthy Children. A Systematic Review and Meta-Analysis

RATIONALE

Respiratory muscle strength in children can be assessed by maximal inspiratory pressures (MIP), maximal expiratory pressures (MEP), and sniff nasal inspiratory pressures (SNIP). However, previous studies involved small cohorts of healthy children and reported wide reference ranges.

OBJECTIVES

To perform a systematic review to summarize existing reference ranges for MIP, MEP, and SNIP tests in healthy children and to conduct a meta-analysis to develop comprehensive prediction equations.

DATA SOURCES

Five databases were searched for relevant studies from database inception to May 29, 2017.

DATA EXTRACTION

Study inclusion was limited to publications that evaluated MIP, MEP, and SNIP values in healthy children aged 18 years or younger. Studies were also excluded if testing methodology differed greatly from the 2002 American Thoracic Society Statement on Respiratory Muscle Testing. Requests for raw data were made to authors via e-mail.

SYNTHESIS

A total of 18 studies including 3,509 children were systematically reviewed. Diagnostic accuracy of the included studies was assessed using the QUADAS-2 tool, which revealed a high risk of bias for flow and timing and for applicability that may influence the generalizability of our findings. All 18 studies evaluated respiratory pressures in children in seated position. MIP tests were conducted from residual volume, MEP tests from total lung capacity, and SNIP tests from functional residual capacity. The MIP and MEP values in three age groups for boys and girls were summarized using meta-analysis based on individual participant data from five studies containing 1,709 healthy children. Further analyses showed that MIP and MEP were significantly greater in boys than in girls (P < 0.0001). In both sexes, MEP values were always greater than MIP values (P < 0.05). Multivariable random effects models were then performed to establish sex-specific prediction equations. These equations found age, height, and weight to be significant predictor variables. Only two studies with SNIP values from healthy children were included in the review, but they were not part of the meta-analysis.

CONCLUSIONS

We summarized the available reference ranges for MIP, MEP, and SNIP tests based on existing literature, especially for three age groups, and developed prediction equations that can be used in pulmonary function laboratories to aid clinicians. Existing literature on SNIP tests is limited, and future studies are encouraged to explore their use in children. Systematic review registered with the International Prospective Register of Systematic Reviews (PROSPERO; CRD42017072004).

Tension Pneumocephalus from Positive Pressure Ventilation Following Endoscopic Skull Base Surgery: Case Series and an Institutional Protocol for the Management of Postoperative Respiratory Distress

BACKGROUND

Tension pneumocephalus (TP) is a rare but feared complication of endoscopic endonasal skull base surgery. In contrast to simple pneumocephalus, which is common after endoscopic transnasal approaches and managed conservatively, TP represents a neurosurgical emergency and mandates urgent decompression.

CASE DESCRIPTION

Here we present 2 cases of TP as a consequence of positive pressure ventilation following endoscopic endonasal skull base surgery. Both occurred during resuscitation for postoperative hypoxia. These cases prompted the development of an institution-wide protocol to identify and manage patients at risk of TP after extended skull base approaches.

CONCLUSIONS

To our knowledge, these are the only such cases of postoperative TP following positive pressure ventilation in the literature.

Evaluation of Respiratory Muscle Strength and Diaphragm Ultrasound: Normative Values, Theoretical Considerations, and Practical Recommendations

BACKGROUND

Reference values derived from existing diaphragm ultrasound protocols are inconsistent, and the association between sonographic measures of diaphragm function and volitional tests of respiratory muscle strength is still ambiguous.

OBJECTIVE

To propose a standardized and comprehensive protocol for diaphragm ultrasound in order to determine lower limits of normal (LLN) for both diaphragm excursion and thickness in healthy subjects and to explore the association between volitional tests of respiratory muscle strength and diaphragm ultrasound parameters.

METHODS

Seventy healthy adult subjects (25 men, 45 women; age 34 ± 13 years) underwent spirometric lung function testing, determination of maximal inspiratory and expiratory pressure along with ultrasound evaluation of diaphragm excursion and thickness during tidal breathing, deep breathing, and maximum voluntary sniff. Excursion data were collected for amplitude and velocity of diaphragm displacement. Diaphragm thickness was measured in the zone of apposition at total lung capacity (TLC) and functional residual capacity (FRC). All participants underwent invasive measurement of transdiaphragmatic pressure (Pdi) during different voluntary breathing maneuvers.

RESULTS

Ultrasound data were successfully obtained in all participants (procedure duration 12 ± 3 min). LLNs (defined as the 5th percentile) for diaphragm excursion were as follows: (a) during tidal breathing: 1.2 cm (males; M) and 1.2 cm (females; F) for amplitude, and 0.8 cm/s (M) and 0.8 cm/s (F) for velocity, (b) during maximum voluntary sniff: 2.0 cm (M) and 1.5 cm (F) for amplitude, and 6.7 (M) cm/s and 5.2 cm/s (F) for velocity, and (c) at TLC: 7.9 cm (M) and 6.4 cm (F) for amplitude. LLN for diaphragm thickness was 0.17 cm (M) and 0.15 cm (F) at FRC, and 0.46 cm (M) and 0.35 cm (F) at TLC. Values for males were consistently higher than for females, independent of age. LLN for diaphragmatic thickening ratio was 2.2 with no difference between genders. LLN for invasively measured Pdi during different breathing maneuvers are presented. Voluntary Pdi showed only weak correlation with both diaphragm excursion velocity and amplitude during forced inspiration.

CONCLUSIONS

Diaphragm ultrasound is an easy-to-perform and reproducible diagnostic tool for noninvasive assessment of diaphragm excursion and thickness. It supplements but does not replace respiratory muscle strength testing.

The effect of 50% oxygen on PtCO2 in patients with stable COPD, bronchiectasis, and neuromuscular disease or kyphoscoliosis: randomised cross-over trials

BACKGROUND

High-concentration oxygen therapy causes increased arterial partial pressure of carbon dioxide (PaCO2) in patients with COPD, asthma, pneumonia, obesity and acute lung injury. The objective of these studies was to investigate whether this physiological response to oxygen therapy occurs in stable patients with neuromuscular disease or kyphoscoliosis, and bronchiectasis.

METHODS

Three randomised cross-over trials recruited stable patients with neuromuscular disease or kyphoscoliosis (n = 20), bronchiectasis (n = 24), and COPD (n = 24). Participants were randomised to receive 50% oxygen and 21% oxygen (air), each for 30 min, in randomly assigned order. The primary outcome was transcutaneous partial pressure of carbon dioxide (PtCO2) at 30 min. The primary analysis was a mixed linear model.

RESULTS

Sixty six of the 68 participants had baseline PtCO2 values < 45 mmHg. The intervention baseline adjusted PtCO2 difference (95% CI) between oxygen and room air after 30 min was 0.2 mmHg (- 0.4 to 0.9), P = 0.40; 0.5 mmHg (- 0.2 to 1.2), P = 0.18; and 1.3 mmHg (0.7 to 1.8), P < 0.001, in the neuromuscular/kyphoscoliosis, bronchiectasis and COPD participants respectively.

CONCLUSIONS

The small increase in PtCO2 in the stable COPD patients with high-concentration oxygen therapy contrasts with the marked increases in PaCO2 seen in the setting of acute exacerbations of COPD. This suggests that the model of studying the effects of high-concentration oxygen therapy in patients with stable respiratory disease is not generalisable to the use of oxygen therapy in the acute clinical setting. Appropriate studies of high-concentration compared to titrated oxygen in acute clinical settings are needed to determine if there is a risk of oxygen-induced hypercapnia in patients with neuromuscular disease, kyphoscoliosis or bronchiectasis.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry ACTRN12615000970549 Registered 16/9/15, ACTRN12615000971538 Registered 16/9/15 and ACTRN12615001056583 Registered 7/10/15.

Reference values of sniff nasal inspiratory pressure in healthy children

OBJECTIVE

To determine reference values of sniff nasal inspiratory pressure (SNIP) in healthy children.

METHODS

This cross-sectional observational study included healthy children aged 6 to 11 years of both sexes. The volunteers underwent a pulmonary function test to rule out respiratory disorders. Respiratory muscle strength was measured using maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP), respectively, with MIP close to functional residual capacity (FRC) and residual volume, while MEP to total lung capacity. SNIP was performed through the nostril contralateral to the occlusion, close to FRC. Two 6-minute walk tests were performed to assess functional exercise capacity.

RESULTS

The sample comprised 121 healthy children (62 girls); 54% presented body mass index (BMI) percentile less than 85th and 46% more than equal to 85th percentile, higher than expected. SNIP values were similar between sexes (91.1 ± 21.0 cmH₂ O in girls and 87.7 ± 19.4 cmH₂ O in boys; P = .36) as well as the means of lower limits of normal (56.88 cmH₂ O for girls and 56.66 cmH₂ O for boys). Girls presented SNIP measurements larger than those of the MIP of FRC (P < .0001), while boys presented similar mean values for both. We found a positive correlation between SNIP and BMI percentile (r = .25, P = .04) in girls, unlike boys, in whom no correlation was observed.

CONCLUSIONS

SNIP reference values and mean lower limits of normal were defined for healthy children aged 6 to 11. BMI percentile seems to positively influence the inspiratory muscle strength measured by SNIP in girls only.

Relationship Between Respiratory Muscle Strength, Handgrip Strength, and Muscle Mass in Hospitalized Patients

BACKGROUND

Minimal information is available to validate measurement of respiratory muscle strength (RMS) in the clinical setting. The purpose of this study was to determine the correlation between maximal inspiratory pressure (MIP), maximal expiratory pressure (MEP), and sniff nasal inspiratory pressure (SNIP) with handgrip strength (HGS) and cross sectional muscle area obtained via diagnostic abdominal computed tomography (CT).

MATERIALS AND METHODS

Measures of MIP, MEP, SNIP, and HGS were obtained from individuals that participated in a previously published study; individuals who had an abdominal CT completed with (±)7 days of obtaining RMS measures were included. Both RMS and HGS were measured within 48-72 hours of admission; for RMS, the highest absolute (cm H₂ O) and percent predicted values were recorded, and the average of 3 HGS measurements (kg) was documented. Cross-sectional muscle area (cm² ) at the third lumbar region was recorded. Spearman's correlation coefficient was used to assess the relationship between variables.

RESULTS

A total of 35 participants were included. HGS was correlated to absolute MIP (r_s = 0.62, r_s = 0.61), MEP (r_s = 0.74, r_s = 0.73), and SNIP (r_s = 0.58, r_s = 0.54) for males and females, respectively. Crosss-sectional muscle area was correlated with absolute MIP (r_s = 0.66), MEP (r_s = 0.58), and SNIP (r_s = 0.783) for men and absolute SNIP (r_s = 0.56) among women.

CONCLUSION

Measures of RMS represent a promising assessment of muscle mass and function among hospitalized patients.

Ventilator-induced diaphragm dysfunction: translational mechanisms lead to therapeutical alternatives in the critically ill

Mechanical ventilation [MV] is a life-saving technique delivered to critically ill patients incapable of adequately ventilating and/or oxygenating due to respiratory or other disease processes. This necessarily invasive support however could potentially result in important iatrogenic complications. Even brief periods of MV may result in diaphragm weakness [i.e., ventilator-induced diaphragm dysfunction [VIDD]], which may be associated with difficulty weaning from the ventilator as well as mortality. This suggests that VIDD could potentially have a major impact on clinical practice through worse clinical outcomes and healthcare resource use. Recent translational investigations have identified that VIDD is mainly characterized by alterations resulting in a major decline of diaphragmatic contractile force together with atrophy of diaphragm muscle fibers. However, the signaling mechanisms responsible for VIDD have not been fully established. In this paper, we summarize the current understanding of the pathophysiological pathways underlying VIDD and highlight the diagnostic approach, as well as novel and experimental therapeutic options.

Differences in Respiratory Muscle Strength Measures in Well-Nourished and Malnourished Hospitalized Patients

BACKGROUND

Objective indicators of nutritional status are essential for accurate identification of malnutrition. Previous research has indicated an association between measures of respiratory muscle strength (RMS) and nutritional status. Measurement of RMS-including maximal inspiratory pressure (MIP), maximal expiratory pressure (MEP), and sniff nasal inspiratory pressure (SNIP)-may provide evidence to support the assessment of nutritional status in hospitalized patients.

OBJECTIVE

The purpose of this study was to determine whether there was a difference in MIP, MEP, and SNIP between well-nourished and malnourished hospitalized patients.

DESIGN

A cross-sectional study was conducted.

PARTICIPANTS/SETTING

Patients were screened for eligibility criteria on admission by means of electronic medical records in general medical or surgical units at a tertiary care hospital in Chicago, IL, from January 2016 to January 2017. A total of 140 patients were included for analysis.

MAIN OUTCOMES MEASURED

The primary outcome was detection of differences in measures of RMS between malnourished and well-nourished hospitalized patients. Nutritional status was assessed using subjective global assessment and Academy of Nutrition and Dietetics/American Society for Parenteral and Enteral Nutrition (Academy/ASPEN) criteria recommended to identify malnutrition. The MIP, MEP, and SNIP measures were obtained and reported as absolute values (expressed in centimeters of water) and percent of predicted values.

STATISTICAL ANALYSIS

Independent t tests or Mann-Whitney U tests were used to determine differences in RMS measures between patients assessed as well nourished and those assessed as malnourished, depending on normality.

RESULTS

Compared with well-nourished patients, malnourished patients identified by subjective global assessment criteria had significantly lower absolute SNIP (73.7±28.7 vs 59.5±27.1 cm H₂O, P=0.004) and percent of predicted SNIP (78.6%±26.3% vs 64.8%± 30.0% predicted, P=0.006). Similarly, compared with well-nourished patients when Academy/ASPEN guidelines were used, malnourished individuals had significantly lower absolute SNIP (76.5±28.6 vs 58.3±26.3 cm H₂O, P<0.001), percent of predicted SNIP (81.4%±26.4% vs 63.5%±28.7% predicted, P<0.001), absolute MIP (83.5±34.6 vs 71.1±33.6 cm H₂O, P=0.05), and absolute MEP (108.7±36.6 vs 94.2±39.9 cm H₂O, P=0.04).

CONCLUSION

Differences in RMS between well-nourished and malnourished patients were observed when SNIP measures were used. However, there were no differences in MIP and MEP measures. Further research is needed to build on the findings from this study.

Respiratory muscle testing in amyotrophic lateral sclerosis: a practical approach

In amyotrophic lateral sclerosis (ALS), respiratory muscle weakness leads to respiratory failure and death. Non-invasive positive pressure ventilation (NIPPV) appears to reduce lung function decline, thus improving survival and quality-of-life of patients affected by the disease. Unfortunately, clinical features and timing to start NIPPV are not well defined. Starting from recent findings, we examine established and novel tests of respiratory muscle function that could help clinicians decide whether and when to start NIPPV in ALS. Non-invasive tests estimate the function of inspiratory, expiratory, and bulbar muscles, whereas clinical examination allows to assess the overall neurologic and respiratory symptoms and general conditions. Most of the studies recommend that together with a thorough clinical evaluation of the patient according to current guidelines, vital capacity, maximal static and sniff nasal inspiratory pressures, maximal static expiratory pressures and peak cough expiratory flow, and nocturnal pulse oximetry be measured. A sound understanding of physiology can guide the physician also through the current armamentarium for additional supportive treatments for ALS, such as symptomatic drugs and new treatments to manage sialorrhea and thickened saliva, cough assistance, air stacking, and physiotherapy. In conclusion, careful clinical and functional evaluation of respiratory function and patient's preference are key determinants to decide "when" and "to whom" respiratory treatments can be provided.

Inspiratory loading exercises on respiratory muscle function in post-operative gastroplasty patients: a randomized clinical trial

Abstract Introduction: The gastroplasty post-operative period can alter respiratory mechanics and predispose patients to respiratory complications. Objective: The objective was to evaluate the effects of exercises with inspiratory load on respiratory muscle function and on the prevalence of atelectasis after gastroplasty. Method: 40 participants were randomly allocated into two groups: Control Group (CG), its members underwent conventional respiratory physical therapy (CRP) and the Inspiratory Load Group (ILG), its members performed exercises with linear inspiratory pressure load, with 40% of the maximum inspiratory pressure (MIP), associated with CRP. Therapy procedures were conducted twice during the immediate post-operative period and thrice on the first post-operative day. In addition to evaluating the MIP, the nasal inspiratory pressure (NIP) and the sustained maximum inspiratory pressure (SMIP) were evaluated before and after treatment. Analysis of variance followed by the Bonferroni correction were applied considering a 5% significance level (p < 0.05). Results: There was no significant difference in NIP and SMIP values when the pre- and post-operative periods were compared for the ILG; however, these values were significantly lower for the CG, also with intergroup differences in NIP values. Atelectasis prevalence was 5% for ILG and 15% for CG, with no intergroup difference. Conclusion: The inspiratory muscle strength and resistance of the respiratory muscles were maintained in the group that performed exercises with inspiratory load associated with CRP, with a low rate of atelectasis after gastroplasty.

Inspiratory muscle strength training improves lung function in patients with the hypermobile Ehlers-Danlos syndrome: A randomized controlled trial

As exertional inspiratory dyspnea is a common disabling complaint in hypermobile Ehlers-Danlos syndrome (hEDS) often also known as joint hypermobility syndrome (JHS), we investigated inspiratory muscle (IM) strength in patients with hEDS, and we assessed the effects of IM training (IMT) on IM strength, lung function, and exercise capacity. A prospective evaluation of IM strength followed by a randomized controlled trial of IMT was performed in women with hEDS. Sniff nasal inspiratory pressure (SNIP) was used to routinely measure IM strength and IMT was carried out using a pressure threshold device. IM strength (main outcome), cardiopulmonary function, exercise capacity, and emotional distress of both the treated and control groups were evaluated at the start and at the end of the 6-week training period. IM strength was reduced (<80% of predicted) in 77% of patients (80/104). Lung function was normal, although 24% of patients had a higher forced expiratory vital capacity (FVC) than normal and 12% of patients had a higher total lung capacity (TLC) than normal. Both the IMT and control groups (n = 20) had similar baseline characteristics. Significant changes were noted only in the IMT group after IMT. At the end of the program, IMT improved SNIP (20%) (before: 41 ± 17 cm H₂ O [28, 53] vs. after: 49 ± 18 cm H₂ O [34;65]), six-minute walking distance (6MWD) (60 m) (455 ± 107 m [379,532] vs. 515 ± 127 m [408, 621]), and forced expiratory volume in one second (FEV1) (285 mL) (94 ± 14% pred [84,104] vs. 103 ± 11% pred [94, 112]). IM strength is significantly reduced in patients with hEDS. IMT improved IM strength, lung function, and exercise capacity. Our findings suggest that IMT should be added to usual care.

A case of unexplained dyspnoea: when lung function testing matters!

“Lung function corner” articles in Breathe present the results of a lung function test and the authors then debate the interpretation, including potential controversies and background from the literature. As section editors of this newly created section of Breathe, we felt it was important to write the first article, which highlights the usefulness of lung function testing in guiding clinical diagnosis especially in difficult cases such the one we discuss here.

Diverse methods are available for assessment of the respiratory muscles; the technique used should be tailored to the question posed.http://ow.ly/ChbX30m91bt

The Pathophysiology of Respiratory Failure: Control of Breathing, Respiratory Load, and Muscle Capacity

The purpose of this review is to provide an overview on how interactions between control of breathing, respiratory load, and muscle function may lead to respiratory failure. The mechanisms involved vary according to the underlying pathology, but respiratory failure is most often the result of an imbalance between the muscular pump and the mechanical load placed upon it. Changes in respiratory drive and response to CO2 seem to be important contributors to the pathophysiology of respiratory failure. Inspiratory muscle dysfunction is also frequent but is not a mandatory prerequisite to respiratory failure since increased load may also be sufficient to precipitate it. It is crucial to recognize these interactions to be able to timeously establish patients on mechanical ventilation and adapt the ventilator settings to their respiratory system physiology.

Avoiding Respiratory and Peripheral Muscle Injury During Mechanical Ventilation: Diaphragm-Protective Ventilation and Early Mobilization

Both limb muscle weakness and respiratory muscle weakness are exceedingly common in critically ill patients. Respiratory muscle weakness prolongs ventilator dependence, predisposing to nosocomial complications and death. Limb muscle weakness persists for months after discharge from intensive care and results in poor long-term functional status and quality of life. Major mechanisms of muscle injury include critical illness polymyoneuropathy, sepsis, pharmacologic exposures, metabolic derangements, and excessive muscle loading and unloading. The diaphragm may become weak because of excessive unloading (leading to atrophy) or because of excessive loading (either concentric or eccentric) owing to insufficient ventilator assistance.

Genioglossus muscle activity during sniff and reverse sniff in healthy men

NEW FINDINGS

What is the central question of this study? Maximal sniff nasal inspiratory and reverse sniff nasal expiratory pressures are measured as inspiratory and expiratory muscle strength, respectively. Is the genioglossus muscle activated during short maximal inspiratory and expiratory efforts through the nose? What is the main finding and its importance? Genioglossus muscle activity occurred with inspiratory muscle activity during a maximal sniff and with expiratory muscle activity during a maximal reverse sniff. These results indicate that genioglossus muscle activity is closely related to the generation of maximal sniff nasal inspiratory and reverse sniff nasal expiratory pressures.

ABSTRACT

Maximal sniff nasal inspiratory pressure (SNIP_max ) is widely used to assess inspiratory muscle strength. The sniff nasal inspiratory pressure (SNIP) is lower in patients with neuromuscular disease with bulbar involvement compared with those without, possibly owing to impaired upper airway muscle function. However, the degree to which the genioglossus (GG) muscle, one of the upper airway muscles, is activated during inspiratory and expiratory efforts through the nose remains unclear. Therefore, we examined GG activity during short and sharp inspiratory and expiratory efforts through the nose, i.e. sniff and reverse sniff manoeuvres. In eight normal young subjects, we inserted fine wire electrodes into the GG muscle, parasternal intercostal and scalene (inspiratory) muscles and transversus abdominis (expiratory) muscle. We assessed EMG activity of each muscle and measured SNIP and reverse sniff nasal expiratory pressure (RSNEP) during sniffs and reverse sniffs from low to high intensities in the sitting position. The highest SNIP and RSNEP were analysed as SNIP_max and maximal RSNEP (RSNEP_max ), respectively. In each subject, GG EMG activity increased linearly with increasing SNIP and RSNEP. The SNIP_max and RSNEP_max were -85.1 ± 15.9 and 83.2 ± 24.2 cmH₂ O, respectively. Genioglossus EMG activity varied with EMG activity of the parasternal intercostal and scalene muscles during generation of SNIP_max and with EMG activity of the transversus abdominis muscle during RSNEP_max . Genioglossus EMG activity during generation of SNIP_max was higher than during RSNEP_max (62.9 ± 31.1% EMG of SNIP_max , P = 0.012). These results suggested that GG activity was closely related to the generation of both SNIP_max and RSNEP_max .

Prospective and longitudinal natural history study of patients with Type 2 and 3 spinal muscular atrophy: Baseline data NatHis-SMA study

Spinal muscular atrophy (SMA) is a monogenic disorder caused by loss of function mutations in the survival motor neuron 1 gene, which results in a broad range of disease severity, from neonatal to adult onset. There is currently a concerted effort to define the natural history of the disease and develop outcome measures that accurately capture its complexity. As several therapeutic strategies are currently under investigation and both the FDA and EMA have recently approved the first medical treatment for SMA, there is a critical need to identify the right association of responsive outcome measures and biomarkers for individual patient follow-up. As an approved treatment becomes available, untreated patients will soon become rare, further intensifying the need for a rapid, prospective and longitudinal study of the natural history of SMA Type 2 and 3. Here we present the baseline assessments of 81 patients aged 2 to 30 years of which 19 are non-sitter SMA Type 2, 34 are sitter SMA Type 2, 9 non-ambulant SMA Type 3 and 19 ambulant SMA Type 3. Collecting these data at nine sites in France, Germany and Belgium established the feasibility of gathering consistent data from numerous and demanding assessments in a multicenter SMA study. Most assessments discriminated between the four groups well. This included the Motor Function Measure (MFM), pulmonary function testing, strength, electroneuromyography, muscle imaging and workspace volume. Additionally, all of the assessments showed good correlation with the MFM score. As the untreated patient population decreases, having reliable and valid multi-site data will be imperative for recruitment in clinical trials. The pending two-year study results will evaluate the sensitivity of the studied outcomes and biomarkers to disease progression.

Trial Registration: ClinicalTrials.gov (NCT02391831).

AIRWAY POSITIVE PRESSURE VS. EXERCISES WITH INSPIRATORY LOADING FOCUSED ON PULMONARY AND RESPIRATORY MUSCULAR FUNCTIONS IN THE POSTOPERATIVE PERIOD OF BARIATRIC SURGERY

BACKGROUND

Bariatric surgery can trigger postoperative pulmonary complications due to factors inherent to the procedure, mainly due to diaphragmatic dysfunction.

AIM

To evaluate and compare the effects of two levels of positive pressure and exercises with inspiratory load on lung function, inspiratory muscle strength and respiratory muscle resistance, and the prevalence of atelectasis after gastroplasty.

METHODS

Clinical, randomized and blind trial, with subjects submitted to bariatric surgery, allocated to two groups: positive pressure group, who received positive pressure at two levels during one hour and conventional respiratory physiotherapy and inspiratory load group, who performed exercises with load linear inspiratory pressure, six sets of 15 repetitions, in addition to conventional respiratory physiotherapy, both of which were applied twice in the immediate postoperative period and three times a day on the first postoperative day. Spirometry was performed for pulmonary function analysis, nasal inspiratory pressure for inspiratory muscle strength and incremental test of respiratory muscle resistance for sustained maximal inspiratory pressure, both preoperatively and on hospital discharge on the second postoperative day.

RESULTS

There was no significant difference (p> 0.05) in the expiratory reserve volume and in the tidal volume in the pre and postoperative periods when compared intra and intergroup. There was no significant difference (p>0.05) in the nasal inspiratory pressure and the maximal inspiratory pressure maintained in the inspiratory load group in the intragroup evaluation, but with a significant difference (p<0.05) compared to the positive pressure group. The prevalence of atelectasis was 5% in both groups with no significant difference (p>0.05) between them.

CONCLUSION

Both groups, associated with conventional respiratory physiotherapy, preserved expiratory reserve volume and tidal volume and had a low atelectasis rate. The inspiratory loading group still maintained inspiratory muscle strength and resistance of respiratory muscles.

Sniff nasal inspiratory pressure (SNIP) in amyotrophic lateral sclerosis: Relevance of the methodology for respiratory function evaluation

OBJECTIVES

We investigated two different methodological approaches for determining nasal inspiratory pressure during a sniff (SNIP) in patients with Amyotrophic Lateral Sclerosis (ALS).

PATIENTS AND METHODS

We included 37 ALS patients and 11 controls. SNIP was measured in the sitting position, performed in each nostril with (SNIPocclud) and without (SNIPopen) closing the contralateral nostril. The best of 3 consistent results was considered for analyses. Patients were also assessed with MIP and the revised functional ALS rating scale (ALSFRS-R). Mann-Whitney U test, Wilcoxon test and Spearman's rank correlation coefficient with Bonferroni correction were applied. Coefficient of variation (CV) was calculated.

RESULTS

SNIP was significantly lower in patients than controls, either for SNIPopen (p = 0.011) or SNIPocclud (p = 0.002). SNIPopen values were significantly lower both in ALS patients and controls than SNIPocclud (p < 0.001 and p = 0.007, respectively). SNIPopen CV was 8.14% and 8.51%, while SNIPocclud CV was 4.98% and 6.37%, respectively for controls and patients. SNIPopen and SNIPocclud were strongly correlated in both groups (r = 0.761 for controls; r = 0.768 for patients). In ALS, both methods were moderately correlated with MIP (respectively r = 0.525, p = 0.006 and r = 0.685, p < 0.001) and the respiratory subscore of ALSFRS-R (respectively r = 0.525, p = 0.001 and r = 0.64, p < 0.001). Although bulbar and spinal onset patients presented no differences for SNIPopen (p = 0.157), significant differences were found for SNIPocclud (p = 0.018).

CONCLUSION

SNIPocclud should be considered when evaluating ALS patients as its values present lower variability and favor longer follow-up.

Early occurrence of inspiratory muscle weakness in Parkinson's disease

INTRODUCTION

In Parkinson's disease (PD), respiratory insufficiency (including functional and muscle disorders) can impact dysarthria and swallowing. Most studies of this topic have been performed retrospectively in populations of patients with advanced PD. The objective of the present study was to characterize lung function (under off-drug conditions) in early-stage PD patients at baseline and then again two years later.

METHODS

Forty-one early-stage PD patients (mean ± SD age: 61.7 ± 7.7; mean ± SD disease duration: 1.9 ± 1.7 years) were prospectively enrolled and compared with 36 age-matched healthy controls. Neurological evaluations and pulmonary function testing were performed in the off-drug condition at the inclusion visit and then two years later.

RESULTS

Pulmonary function testing did not reveal any restrictive or obstructive disorders; at baseline, inspiratory muscle weakness was the only abnormality observed in the PD group (in 53.7% of the patients, vs. 25% in controls; p = 0.0105). The PD patients had a lower mean maximal inspiratory mouth pressure than controls and a lower sniff nasal inspiratory pressure. Two years after the initiation of chronic treatment with antiparkinsonian medications, the maximal inspiratory mouth pressure and the sniff nasal inspiratory pressure tended to be higher. Lastly, overall motor outcomes were not significantly worse in patients with inspiratory muscle weakness than in patients without inspiratory muscle weakness.

CONCLUSION

Inspiratory muscle weakness seems to be common in patients with early-stage PD, and was seen to be stable over a two-year period. Additional long-term follow-up studies are required to specify the impact of this new feature of PD.