Sniff Nasal Inspiratory Pressure Research Articles

Office-based respiratory assessment in patients with generalized myasthenia gravis

Patients with myasthenia gravis (MG) can present with respiratory dysfunction, ranging from exercise intolerance to overt respiratory failure, increased fatigue, or sleep-disordered breathing. To investigate the value of multiple respiratory tests in MG, we performed clinical and respiratory assessments in patients with mild to moderate generalized disease. One-hundred and thirty-six patients completed the myasthenia gravis quality-of-life score(MG-QOL-15), myasthenia gravis impairment index(MGII), Epworth sleepiness scale(ESS), University of California-San Diego Shortness of Breath Questionnaire(UCSD-SOB), Modified Medical Research Council Dyspnea Scales(MRC-DS), supine and upright forced vital capacity(FVC), maximal inspiratory pressures(MIPs) and sniff nasal inspiratory pressures(SNIP). Seventy-three (54 %) had respiratory and/or bulbar symptoms and 45 (33 %) had baseline abnormal FVC, with no significant postural changes (p = 0.89); 55 (40.4 %) had abnormal MIPs and 50 (37 %) had abnormal SNIPs. Overall, there were low scores on respiratory and disability scales. Females had increased odds of presenting with abnormal FVC (OR 2.89, p = 0.01) and MIPs (OR 2.48, p = 0.022). There were significant correlations between MIPs, FVC and SNIPs; between MGII/MG-QOL15 and UCSD-SOB/MRC-DS and between ESS and respiratory scales in the whole group. Our data suggests that office-based respiratory measurements are a useful screening method for stable MG patients, even when presenting with minimal respiratory symptoms and no significant disability.

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.

Cervical and thoracic spinal cord gray matter atrophy is associated with disability in patients with amyotrophic lateral sclerosis.

In amyotrophic lateral sclerosis (ALS), there is an unmet need for more precise patient characterization through quantitative, ideally operator-independent, assessments of disease extent and severity. Radially sampled averaged magnetization inversion recovery acquisitions (rAMIRA) magnetic resonance imaging enables gray matter (GM) and white matter (WM) area quantitation in the cervical and thoracic spinal cord (SC) with optimized contrast. We aimed to investigate rAMIRA-derived SC GM and SC WM areas and their association with clinical phenotype and disability in ALS. A total of 36 patients with ALS (mean [SD] age 61.7 [12.6] years, 14 women) and 36 healthy, age- and sex-matched controls (HCs; mean [SD] age 63.1 [12.1] years, 14 women) underwent two-dimensional axial rAMIRA imaging at the inter-vertebral disc levels C2/3-C5/C6 and the lumbar enlargement level Tmax. ALS Functional Rating Scale-revised (ALSFRS-R) score, muscle strength, and sniff nasal inspiratory pressure (SNIP) were assessed. Compared to HCs, GM and WM areas were reduced in patients at all cervical levels (p < 0.0001). GM area (p = 0.0001), but not WM area, was reduced at Tmax. Patients with King's Stage 3 showed significant GM atrophy at all levels, while patients with King's Stage 1 showed significant GM atrophy selectively at Tmax. SC GM area was significantly associated with muscle force at corresponding myotomes. GM area at C3/C4 was associated with ALSFRS-R (p < 0.001) and SNIP (p = 0.0016). Patients with ALS assessed by rAMIRA imaging show significant cervical and thoracic SC GM and SC WM atrophy. SC GM area correlates with muscle strength and clinical disability. GM area reduction at Tmax may be an early disease sign. Longitudinal studies are warranted.

Pilot observational cohort study to determine whether waveform and flow traces from mechanical insufflation–exsufflation (MI-E) can be used to identify laryngeal responses to MI-E and thus optimise treatment algorithms in neuromuscular patients in a tertiary centre: a protocol description

IntroductionPatients with neuromuscular disease often have a weak and ineffective cough due to respiratory muscle weakness. One treatment option is mechanical insufflation–exsufflation (MI-E), also known as cough assist, which is...

Does inspiratory muscle training improve lung function and quality of life in people with inclusion body myositis? A pilot study

Inclusion body myositis is the most common acquired myositis in adults, predominantly weakening forearm flexor and knee extensor muscles. Subclinical respiratory muscle weakness has recently been recognised in people with inclusion body myositis, increasing their risk of respiratory complications. Inspiratory muscle training, a technique which demonstrates efficacy and safety in improving respiratory function in people with neuromuscular disorders, has never been explored in those with inclusion body myositis. In this pilot study, six adults with inclusion body myositis (age range 53 to 81 years) completed eight weeks of inspiratory muscle training. Measures of respiratory function, quality of life, sleep quality and a two-minute walk test were performed pre and post-intervention. All participants improved their respiratory function, with maximal inspiratory pressure, sniff nasal inspiratory pressure and forced vital capacity increasing by an average of 50 % (p = .002), 43 % (p = .018) and 13 % (p = .003) respectively. No significant change was observed in quality of life, sleep quality or two-minute walk test performance. No complications occurred due to inspiratory muscle training This pilot study provides the first evidence that inspiratory muscle training may be safe and effective in people with Inclusion Body Myositis, potentially mitigating the complications of poor respiratory function.

Forced Expiratory Volume in One Second Quotient (FEV1Q) as a Prognostic Factor in Amyotrophic Lateral Sclerosis Patients: Comparing Its Predictive Value to Other Lung Function Measurements.

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder affecting the first and second motor neurons. Forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) have conventionally served as indicators of respiratory muscle strength. Recently, FEV1Q (FEV1 divided by the sex-specific first percentile values of absolute FEV1 in adults with lung disease) has been suggested as a predictor of mortality. While FVC has been utilized as a prognostic factor, FEV1Q has not yet been examined. This retrospective unicenter study evaluated FEV1Q as a predictor of mortality in ALS patients, comparing its predictive efficacy with other measurements, including FEV1, FVC, sniff nasal inspiratory pressure, and maximal inspiratory pressure. The study utilized univariate analysis for each variable employing the Cox proportional hazards model to determine the statistical significance and predictive power of each measurement. Forty-five patients were included, female predominant (60%) and an average age at diagnosis of 69.2 ± 11 years. Almost all (95%) met the criteria for non-invasive ventilation (NIV) and initiated (93%) during the study period, a mean of 137 days after diagnosis. The mortality rate observed was 57%, occurring at a median of 398 days post-diagnosis. On average, patients underwent 1.7 pulmonary function tests, revealing a decline in various parameters, including FEV1, FEV1Q, and FVC. However, only FEV1Q was a statistically significant predictor of mortality (p < 0.0083) in a Cox regression analysis. A negative coefficient for FEV1Q indicated that higher values were associated with a reduced mortality risk, with an average FEV1Q of 2.68 observed at the time of death. FEV1Q emerged as the only statistically significant predictor of mortality among the evaluated respiratory measurements in ALS patients. This study is the first to focus on applying FEV1Q in the clinical evaluation of ALS, marking an initial step in understanding its potential role in patient follow-up. However, further studies are needed before these findings can be incorporated into clinical practice.

Predictive value of maximal inspiratory pressure and sniff nasal inspiratory pressure in Korean ALS patients: Considering racial difference, body mass index, and bulbar impairment

Predictive value of maximal inspiratory pressure and sniff nasal inspiratory pressure in Korean ALS patients: Considering racial difference, body mass index, and bulbar impairment

Reliability of maximal respiratory nasal pressure tests in healthy young adults.

Sniff nasal inspiratory (SNIP) and expiratory pressure (SNEP) may complement the assessment of respiratory muscle strength. Thus, specifying their reliability is relevant to improving the clinical consistency of both tests. To assess the reliability of SNIP and SNEP in healthy young adults. This cross-sectional study included self-reported healthy aged 18 to 29 years. SNIP was performed using a plug to occlude one nostril, while SNEP was conducted using a facemask. Participants performed 20 SNIP and SNEP maneuvers with 30-second intervals in between. The intraclass correlation coefficient (ICC), standard error of measurement (SEM), and minimum detectable change (MDC) assessed the reliability of SNIP and SNEP. Analyses were conducted between the highest peak pressure and the first reproducible maneuver in men and women. The total sample comprised 32 participants: 16 men and 16 women. The ICC, SEM, and MDC for SNIP maneuvers were 0.994 (95%CI 0.988 to 0.997), 1.820 cmH2O, and 5.043 cmH2O, respectively. For SNEP, these parameters were 0.950 (95%CI 0.897 to 0.976), 6.03 cmH2O, and 16.716 cmH2O. The SNIP and SNEP in men showed ICC of 0.992 (95%CI 0.977 to 0.997) and 0.877 (95%CI 0.648 to 0.957), SEM of 2.07 and 7.66 cmH2O, and MDC of 5.74 and 21.23 cmH2O. In women, SNIP and SNEP presented ICC of 0.992 (95%CI 0.977 to 0.997) and 0.957 (95%CI 0.878 to 0.985), SEM of 1.15 and 6.11 cmH2O, and MDC of 3.19 and 16.95 cmH2O. Also, 60% of the highest SNIPs occurred among the 11th and 20th maneuvers in men and women. In men, 55% of the highest SNEPs occurred among the 11th and 20th maneuvers; this value was 50% in women. SNIP and SNEP showed excellent reliability. The reliability of SNIP and SNEP in men was good and excellent, respectively, whereas both tests had excellent reliability in women. Also, women reached the highest peak pressure faster than men in both tests.

Respiratory function in LAMA2-related muscular dystrophy and SELENON-related congenital myopathy, a 1.5-year natural history study

IntroductionLAMA2-related muscular dystrophy (LAMA2-MD) and SELENON(SEPN1)-related congenital myopathy (SELENON-RM) are rare neuromuscular diseases with respiratory impairment from a young age. Prospective natural history studies are needed for prevalence estimations, respiratory characterization, optimizing clinical care and selecting outcome measures for trial readiness. MethodsOur prospective 1.5-year natural history study included spirometry (forced vital capacity (FVC); difference between upright and supine vital capacity (dVC)), respiratory muscle strength tests (sniff nasal inspiratory pressure (SNIP)) (age≥5 years), and diaphragm ultrasound (thickness; thickening; echogenicity; all ages). ResultsTwenty-six LAMA2-MD patients (M = 8, median 21 [9; 31] years) and 11 SELENON-RM patients (M = 8, 20 [10; 33] years) were included. At baseline, 17 (85 %) LAMA2-MD (FVC%: 59 % [33; 68]) and all SELENON-RM patients (FVC%: 34 % [31; 46]) had an impaired respiratory function (FVC%<80 %). Nine (35 %) LAMA2-MD and eight (73 %) SELENON-RM patients received mechanical ventilation at baseline, and two additional SELENON-RM patients started during follow-up. Contrarily to LAMA2-MD, SELENON-RM patients had severe diaphragm atrophy (diaphragm thickness z-score: 2.5 [-3.1; −2.1]) and dysfunction (diaphragm thickness ratio: 1.2 [1.0; 1.7]; dVC: 30 % [7.7; 41]). SNIP was low in both neuromuscular diseases and correlated with motor function. In SELENON-RM, respiratory function decreased during follow-up. ConclusionThe majority of LAMA2-MD and all SELENON-RM patients had respiratory impairment. SELENON-RM patients showed lower respiratory function which was progressive, more prevalent mechanical ventilation, and more severe diaphragm atrophy and dysfunction than LAMA2-MD patients. Spirometry (FVC%, dVC) and respiratory muscle strength tests (SNIP) are useful in clinical care and as outcome measure in clinical trials. Clinical trial numberNCT04478981.

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

Backgroundand 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). MethodsThis 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. ResultsData 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. ConclusionAfter 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.

Causes of hypercapnic respiratory failure: a population-based case-control study

ObjectiveThere are no population-based data on the relative importance of specific causes of hypercapnic respiratory failure (HRF). We sought to quantify the associations between hospitalisation with HRF and potential antecedent causes including chronic obstructive pulmonary disease (COPD), obstructive sleep apnea, and congestive cardiac failure. We used data on the prevalence of these conditions to estimate the population attributable fraction for each cause.MethodsA case–control study was conducted among residents aged ≥ 40 years from the Liverpool local government area in Sydney, Australia. Cases were identified from hospital records based on PaCO2 > 45 mmHg. Controls were randomly selected from the study population using a cluster sampling design. We collected self-reported data on medication use and performed spirometry, limited-channel sleep studies, venous sampling for N-terminal pro-brain natriuretic peptide (NT-proBNP) levels, and sniff nasal inspiratory pressure (SNIP) measurements. Logistic regression analyses were performed using directed acyclic graphs to identify covariates.ResultsWe recruited 42 cases and 105 controls. HRF was strongly associated with post-bronchodilator airflow obstruction, elevated NT-proBNP levels, reduced SNIP measurements and self-reported opioid medication use. There were no differences in the apnoea-hypopnea index or oxygen desaturation index between groups. COPD had the highest population attributable fraction (42%, 95% confidence interval 18% to 59%).ConclusionsCOPD, congestive cardiac failure, and self-reported use of opioid medications, but not obstructive sleep apnea, are important causes of HRF among adults over 40 years old. No single cause accounts for the majority of cases based on the population attributable fraction.

Age Related Burden of Swallowing in Adult Patients Affected by Duchenne Muscular Dystrophy.

In Duchenne muscular dystrophy (DMD), dysphagia is a common but often overlooked symptom, which may affect quality of life (QoL). Its possible causes are progressive deterioration of muscle groups involved in swallowing function (oropharyngeal, inspiratory muscles) or impairment of autonomic function. In adult patients with DMD, we aimed to identify predictors of swallowing-related QoL and to compare swallowing-related QoL at different ages. Forty-eight patients aged 30.0±6.6 years were enrolled. Questionnaires were administered: the Swallowing Quality of Life questionnaire (SWAL-QOL) for swallowing-related QoL assessment, and the Compass 31 for autonomic symptoms assessment. The Brooke Upper Extremity Scale was used for upper limbs muscular function assessment. Respiratory and muscle function tests were performed, including spirometry, arterial blood gases, polysomnography, maximal inspiratory pressure (MIP), maximal expiratory pressure and sniff nasal inspiratory pressure. An abnormal composite SWAL-QOL score (≤86) was found in 33 patients. Autonomic symptoms were mild, while a severe impairment was shown by the Brooke Upper Extremity Scale. Spirometry and muscle strength tests demonstrated severe alterations, while diurnal and nocturnal blood gases were normal, due to effective use of noninvasive ventilation. Independent predictors of the composite SWAL-QOL score were age, MIP and Compass 31. A MIP < 22 had an accuracy of 92% in predicting altered swallowing-related QoL. The composite SWAL-QOL score was worse in subjects > 30 years old than in younger patients (64.5±19.2 vs 76.6±16.3, p < 0.02), due to worse scores in items pertinent to mental and social functioning; scores in domains pertinent to the physical function were similar in both groups. In adult DMD, swallowing-related QoL, which is altered in most patients, can be predicted by age, inspiratory muscles strength and autonomic dysfunction symptoms. While swallowing function is already altered in young patients, swallowing-related QoL can progressively worsen with advancing age due to psychological and social factors.

Inspiratory Muscle Training in Nemaline Myopathy.

Respiratory muscle weakness is a common feature in nemaline myopathy. Inspiratory muscle training (IMT) is an intervention that aims to improve inspiratory muscle strength. The aim of this controlled before-and-after pilot study was to investigate if IMT improves respiratory muscle strength in patients with nemaline myopathy. 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). 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. 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.

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.

Effect of Active Physiotherapy With Positive Airway Pressure on Pulmonary Atelectasis After Cardiac Surgery: A Randomized Controlled Study

The authors investigated the effect of active work with positive airway pressure (PAP) in addition to chest physiotherapy (CP) on pulmonary atelectasis (PA) in patients undergoing cardiac surgery with cardiopulmonary bypass. A randomized controlled study. At a single-center tertiary hospital. Eighty adult patients undergoing cardiac surgery (coronary artery bypass grafting, valve surgery, or both), and presenting with PA after tracheal extubation on postoperative days 1 or 2, were randomized from November 2014 to September 2016. Three days of CP, twice daily, associated with active work with PAP effect (intervention group) versus CP alone (control group). Pulmonary atelectasis was assessed by using the radiologic atelectasis score (RAS) measured from daily chest x-rays. All radiographs were reviewed blindly. Among included patients, 79 (99%) completed the trial. The primary outcome was mean RAS on day 2 after inclusion. It was significantly lower in the intervention group (mean difference and 95% CI: -1.1 [-1.6 to -0.6], p < 0.001). The secondary outcomes were the sniff nasal inspiratory pressure measured before and after CP and clinical variables. Sniff nasal inspiratory pressure was significantly higher in the intervention group on day 2 (7.7 [3.0-12.5] cmH2O, p=0.002). The respiratory rate was lower in the intervention group (-3.2 [95% CI -4.8 to -1.6] breaths/min, p < 0.001) on day 2. No differences were found between the 2 groups for percutaneous oxygen saturation/oxygen requirement ratio, heart rate, pain, and dyspnea scores. Active work with the PAP effect, combined with CP, significantly decreased the RAS of patients undergoing cardiac surgery after 2 days of CP, with no differences observed in clinically relevant parameters.

Hepatitis E-associated neuralgic amyotrophy: a rare respiratory presentation.

Hepatitis E-associated neuralgic amyotrophy: a rare respiratory presentation.

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

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). 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. 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). 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.

A systematic review and meta-analysis of respiratory dysfunction in Parkinson's disease.

Respiratory dysfunction in Parkinson's disease (PD) is common and associated with increased hospital admission and mortality rates. Central and peripheral mechanisms have been proposed in PD. To date no systematic review identifies the extent and type of respiratory impairments in PD compared with healthy controls. PubMed, EMBASE, CINAHL, Web of Science, Pedro, MEDLINE, Cochrane Library and OpenGrey were searched from inception to December 2021 to identify case-control studies reporting respiratory measures in PD and matched controls. Thirty-nine studies met inclusion criteria, the majority with low risk of bias across Risk of Bias Assessment tool for Non-randomized Studies (RoBANS) domains. Data permitted pooled analysis for 26 distinct respiratory measures. High-to-moderate certainty evidence of impairment in PD was identified for vital capacity (standardised mean difference [SMD] 0.75; 95% CI 0.45-1.05; p < 0.00001; I2 =10%), total chest wall volume (SMD 0.38; 95% CI 0.09-0.68; p=0.01; I2 =0%), maximum inspiratory pressure (SMD 0.91; 95% CI 0.64-1.19; p < 0.00001; I2 =43%) and sniff nasal inspiratory pressure (SMD 0.58; 95% CI 0.30-0.87; p < 0.00001; I2 =0%). Sensitivity analysis provided high-moderate certainty evidence of impairment for forced vital capacity and forced expiratory volume in 1s during medication ON phases and increased respiratory rate during OFF phases. Lower certainty evidence identified impairments in PD for maximum expiratory pressure, tidal volume, maximum voluntary ventilation and peak cough flow. Strong evidence supports a restrictive pattern with inspiratory muscle weakness in PD compared with healthy controls. Limited data for central impairment were identified with inconclusive findings.

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

BackgroundMaximal 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.ObjectivesWe compared SNIP values from three conditions, namely with 30, 60 or 90 s time intervals between repeats, the right (SNIPR) and left (SNIPL) nostril, and the contralateral nostril occluded (SNIPO) or non-occluded (SNIPNO). Additionally, we determined the optimal number of repeats for accurate SNIP measurement.Method52 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.ResultsThere was no significant difference in SNIP depending on the interval between repeats (P = 0.98); subjects preferred the 30 s. SNIPO was significantly higher than SNIPNO (P < 0.00001) but SNIPL and SNIPR 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).ConclusionsWe conclude that SNIPO is a more reliable RMS indicator than SNIPNO, 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.

Non-invasive assessment of fatigue and recovery of inspiratory rib cage muscles during endurance test in healthy individuals.

Fatigue is defined as loss of capacity to develop muscle force and/or velocity that is reversible at rest. We assessed non-invasively the fatigue and recovery of inspiratory rib cage muscles during two respiratory endurance tests in healthy individuals. The sniff nasal inspiratory pressure (SNIP) was assessed before and after two respiratory endurance tests: normocapnic hyperpnea (NH) and inspiratory pressure threshold loading (IPTL). Contractile (maximum rate of pressure development and time to peak pressure) and relaxation parameters (maximum relaxation rate [MRR], time constant of pressure decay [τ], and half relaxation time) obtained from sniff curves and shortening velocity and mechanical power estimated using optoelectronic plethysmography were analyzed during SNIP maneuvers. Respiratory muscle activity (electromyography) and tissue oxygenation (near-infrared spectroscopy-NIRS) were obtained during endurance tests and SNIP maneuvers. Fatigue development of inspiratory rib cage muscles was assessed according to the slope of decay of median frequency. Peak pressure during SNIP decreased after both protocols (p <0.05). MRR, shortening velocity, and mechanical power decreased (p <0.05), whereas τ increased after IPTL (p <0.05). The median frequency of inspiratory rib cage muscles (i.e., sum of sternocleidomastoid, scalene, and parasternal) decreased linearly during IPTL and exponentially during NH, mainly due to the sternocleidomastoid. Fatigue development behaved differently between protocols and relaxation properties (MRR and τ), shortening velocity, and mechanical power changed only in the IPTL.