Measurement Of Maximal Inspiratory Pressure Research Articles

Evaluation of the effect of learning on the full extent of inspiratory and expiratory pressure in healthy adults

BACKGROUND: Measurements of maximal inspiratory and expiratory pressure are used to assess the pressure developed by the respiratory muscles and the passive elastic recoil of the pulmonary system. Such measurements are also used as criteria for weaning from mechanical ventilation, to determine the functional consequences of several systemic diseases and the development of lung diseases and neuromuscular disorders. The test in na outpatient setting is easy to perform, well tolerated and has predictive value OBJECTIVE: To verify the presence of a learning effect in measurements of maximal inspiratory and expiratory pressures. METHODS: We performed 15 sequential measurements of Maximal Inspiratory Pressure and 15 of Maximal Expiratory Pressure in 71 individuals. Results for both series were compared throughout each series. RESULTS: The comparison between the first and the other measurements showed no statistically significant differences. (p > 0.05). CONCLUSIONS: There was no learning effect with 15 repeated measurements of Maximal Inspiratory or Expiratory Pressure in healthy adults.

WS21.7 The relationship of maximum inspiratory pressures with inspiratory muscle weakness and FEV1 in patients with cystic fibrosis chronically infected with Pseudomonas aeruginosa

Background Measurement of Maximum Inspiratory Pressure (PImax) is a sensitive and valid measurement of respiratory muscle strength. PImax is reported to be significantly reduced in Cystic Fibrosis (CF) patients compared to normal controls. In patients with CF, chronic Pseudomonas aeruginosa (Pa) infection independently influences PImax compared to patients who are intermittently or never infected. A value of PImax below 80cmH2O is said to indicate clinically important inspiratory muscle weakness. The relationship between PImax and FEV1 is unclear. Objectives To determine PImax values in a cohort of patients chronically infected with Pa; identify patients who have clinically important inspiratory muscle weakness; and correlate PImax values with FEV1 (% predicted). Methods The best of three PImax, and FEV1, values were recorded in 13 patients attending a CF outpatient clinic for patients with Pa. Results The mean (SD) PImax was 93.69 (20.44) cmH2O. The PImax values ranged from 58–121 cmH2O. The PImax fell below 80cmH2O in four patients (31%). The mean (SD) FEV1 was 59 (24) % predicted. There was a weak positive correlation (r = 0.29) between PImax and FEV1. Conclusion Measurement of PImax, in patients with CF infected with Pa, can identify clinically important inspiratory muscle weakness. PImax in the same population has a weak positive correlation with FEV1. This is now being investigated in a larger CF population.

Inspiratory muscle resistance to fatigue during exercise and simulated airway obstruction

Respiratory muscle fatigue can develop during simulated airway obstruction. The aim of this study was to characterize the pattern of inspiratory muscle fatigue and to assess the resistance to fatigue of diaphragm (D), parasternal (PS), sternocleidomastoid (SM) and scalene (SC). 8 healthy untrained subjects participated in this study. To identify signs of inspiratory muscles fatigue development electromyographic activity of D, PS, SCM and SC was recorded during 5-min exercise with loaded breathing (40 cm H2O/L · s(-1)). The before-to-after exercise measurements of maximal inspiratory pressure (MIP) and EMG power spectrum changes were performed. Maximal inspiratory pressure declined about 12% after exercise test compared with control, whereas the peak magnitude of integrated electrical activity of D, PS, SCM and SC during post-exercise Muller's maneuver was significantly greater than in pre-exercise test in all subjects. The extent ofinspiratory muscles fatigue was evaluated by analysis of shift in centroid frequency (fc) of EMG power spectrum. All subjects demonstrated a significant reduction in fc of PS, SCM and SC.fc of D was not changed. Diaphragm is more resistantto fatigue during obstructive breathing compared with PS, SCM and SC. The data suggest that the reduction of maximum inspiratory pressure in chronic obstructive pulmonary disease also caused primarily by the weakening of the accessory muscles, while the weakness of the diaphragm may occur in the later stages of the disease. The functional failure of accessory muscles is an additional factor, which, along with the additional breathing resistance increases the load on the diaphragm, promoting its fatigue and reduced respiratory reserve.

Inspiratory muscle strength in subjects with tetraplegia: viability of evaluation through the measurement of maximal inspiratory pressure

Objective To analyze the values of maximal inspiratory pressure (MIP) and sniff nasal inspiratory pressure (SNIP) and to verify the existence of concordance between the two evaluation methodologies, in subjects with tetraplegia. Materials and methods Cross-sectional study with 17 tetraplegic men, aged 30.42 ± 7.67 years, who underwent MIP and SNIP evaluation using a respiratory pressure meter. Results The MIP and SNIP values obtained showed no difference when compared to each other (88.42 ± 29.39 vs. 86.68 ± 25.40 cmH2O, respectively). They were, however, significantly lower compared to the predicted values (MIP = 128.92 ± 7.18; SNIP = 114.11 ± 3.19 cmH2O), with the MIP values presenting correlation (r2 = 0.94; p < 0.0001) and concordance with those of the SNIP. Conclusions Both the MIP and SNIP values obtained were lower than the predicted values, indicating a reduction in inspiratory muscle strength (IMS). Both techniques showed correlation and concordance, suggesting that MIP can be used as a noninvasive method for IMS evaluation in this population.

Effects of TENS in living kidney donors submitted to open nephrectomy: a randomized placebo-controlled trial.

Pain is a negative factor in the recovery process of postoperative patients. It causes pulmonary alterations and complications, and it also affects functional capacity. Several studies have investigated the effects of transcutaneous electrical nerve stimulation (TENS) during the postoperative period. However, no studies have assessed the effects of TENS on kidney donors. Thus, the aim of the present study was to evaluate the effect of TENS on pain, walking function, respiratory muscle strength and vital capacity in kidney donors. Seventy-four patients were randomly allocated into two groups: active TENS or placebo TENS. All patients were assessed for pain intensity, respiratory muscle strength, vital capacity and walking function before and after the TENS application on the first day of the postoperative period. The use of active TENS significantly reduced pain at rest (p = 0.006), during the measurement of maximal inspiratory pressure (p = 0.006), during maximal expiratory pressure (p = 0.004) and during vital capacity (p = 0.013). Active TENS also produced a significant increase in maximal expiratory pressure when compared with the placebo TENS group (p = 0.001). Maximal inspiratory pressure, vital capacity and walking function were not significantly different between the two treatment groups. These results suggest that TENS decreases pain intensity at rest and during respiratory manoeuvres and increases maximal expiratory pressure during the postoperative period in kidney donors after open nephrectomy.

Reference values for maximal inspiratory pressure: a systematic review.

Maximal inspiratory pressure (MIP) is the most commonly used measure to evaluate inspiratory muscle strength. Normative values for MIP vary significantly among studies, which may reflect differences in participant demographics and technique of MIP measurement. To perform a systematic review with meta-analyses to synthesize MIP values that represent healthy adults. A systematic literature search was conducted using Medline, EMBASE, Cochrane, Cumulative Index to Nursing and Allied Health (CINAHL) and Sport Discus databases. Two reviewers identified and selected articles, and abstracted data. Methodological quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS) tool. A random-effects model was used to calculate overall means and 95% CIs. Of 22 included articles, MIP data were synthesized according to age group and sex from six reports (n=840) in the meta-analyses. The mean QUADAS score was 3.5 of 7. The age range was between 18 and 83 years (426 men, 414 women). MIP began to decrease with age in the 40 to 60 years age range and continued to fall progressively with age. For the same age group, men tended to have higher MIPs than women. Sensitivity analysis of withdrawing studies from the meta-analysis identified one study that contributed more to heterogeneity in some age groups. MIP was higher in men and decreased with age, which was initially apparent in middle age. Several characteristics of participants and MIP technique influence values in healthy individuals. The present meta-analysis provides normative MIP values that are reflective of a large sample (n=840) and likely represents the broadest representation of participant characteristics compared with previous reports of normative data.

Can maximal inspiratory and expiratory pressures during exercise predict complications in patients submitted to major lung resections? A prospective cohort study

The measurement of maximal inspiratory pressure (PImax) and maximal expiratory pressure (PEmax) generated at the mouth is an accepted non-invasive clinical method for evaluating the strength of respiratory muscles. The aim of our study was to verify whether PImax and PEmax measured before and after a symptom-limited stair-climbing test are associated with complications in patients submitted to major lung resections. In a prospective cohort study of 283 consecutive patients submitted to lobectomy (231) or pneumonectomy (52) with a preoperative symptom-limited stair-climbing test, PImax and PEmax were measured before and immediately after the exercise. PImax and PEmax values were expressed as percentages of predicted values. ΔPImax and ΔPEmax were defined as the percentage difference between the pre- and postexercise values. Logistic regression analysis and the bootstrap resampling technique were performed to identify predictors of cardiopulmonary complications. On average, PImax dropped by 3.6% and PEmax increased by 0.8% after the exercise. In total, 173 patients (61%) experienced a reduction in their PImax after exercise, while 150 (53%) had their PEmax reduced. Postoperative cardiopulmonary complications occurred in 74 patients (26%). Complicated patients had a greater reduction in their PImax compared with non-complicated patients (8.7% vs 2.1%, P = 0.03), whereas ΔPEmax was similar in complicated and non-complicated patients (0.7% vs 1.3%, P = 0.5). Receiver operating characteristic analysis indicated that the best cut-off for predicting complications was a ΔPImax of 10%. Stepwise logistic regression analysis and bootstrap confirmed that ΔPImax of >10 was associated with cardiopulmonary complications after adjusting for baseline and surgical factors (ΔPImax regression coefficient -0.02, P = 0.09, bootstrap frequency 51%). A progressive increase in complications was observed in patients with greater reduction in ΔPImax after exercise, particularly for values >10% reduction. The measurement of PImax at the mouth during exercise represents an additional parameter that can be used to refine risk stratification of lung resection candidates and to identify patients who may benefit from inspiratory muscle training.

Comparison of respiratory muscle strength between elderly subjects after a stroke

The decrease in elastic recoil of the lungs and chest cavity compliance is a major change in the respiratory system with advancing age, when these changes are associated with clinical manifestations of under lying cerebral vascular accident (stroke), respiratory muscle strength of the elderly may be seriously affected, therefore it is necessary to investigate the conditions of respiratory muscle strength in older hemiparetic patients in both the acute and chronic phases. Objective: To compare respiratory muscle strength in elderly hemiparetic patients in both the acute and chronic phases after stroke, evaluated by the values of maximal respiratory pressures, so that the rehabilitation of these individuals will be more targeted. Method: Twenty-nine hemiparetic individuals were evaluated-seventeen in acute and twelve in chronic phases, the values of maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) being measured by means of a manometer. Results: There was no difference between acute and chronic patients, however, measurements of MIP and MEP after the stroke showed statistically significant decreases when compared with predicted values. Conclusion: There was no difference in respiratory muscle strength between the acute and chronic phases, however, the fact that the MIP and MEP were also reduced in all subjects, suggests similar weakness in the respiratory musculature in both phases after stroke, and this condition can be worsened when coupled with the aging process. It is suggested that a program include muscle training for these individuals to have better rehabilitation after their strokes.

Maximum Rate of Pressure Development and Maximal Relaxation Rate of Respiratory Muscles in Patients with Cystic Fibrosis

Respiratory muscle function in patients with cystic fibrosis (CF) has been studied by measurement of maximal inspiratory pressure (P(Imax)), maximal expiratory pressure (P(Emax)), and the pressure-time index of the respiratory muscles (PTI(mus)). The maximum rate of pressure development (MRPD) during P(Imax) (MRPD-P(Imax)), MRPD during P(Emax) (MRPD-P(Emax)), maximal relaxation rate (MRR) during P(Imax) (MRR-P(imax)), and MRR during P(Emax) (MRR-P(Emax)) have not been studied in CF. Our aim was to study MRPD and MRR and investigate their possible application as accessory indices of respiratory muscle function in patients with CF. FEVY, FVC, and maximal expiratory flow between 25% and 75% of vital capacity, body mass index (BMI), upper arm muscle area, P(imax), P(Emax), PTI(mus), MRPD-P(Imax), MRPD-P(Emax), MRR-P(imax), and MRR-P(Emax) were assessed in 123 CF patients and in a control group of 123 healthy subjects matched for age and sex. MRR-P(Emax) was significantly increased and MRPD-P(Emax) was significantly decreased in the CF patients, compared to the healthy controls. In the CF patients MRR-P(Imax) was significantly related to PTI(mus) (P = .02), FEV1 (P = .03), FVC (P = .001), BMI (P < .001), and upper arm muscle area (P < .001). In the CF patients, MRPD-P(Imax) and MRPD- P(Emax) were significantly related to upper arm muscle area (P < .001), BMI (P < .001 and P = .01, respectively), P(Imax) (P < .001), and P(Emax) (P < .001). The CF patients exhibited increased MRR and decreased MRPD during maximal respiratory effort, compared to controls. The differences in MRR-P(imax) and MRPD-P(Imax) between the controls and the complete group of CF patients were not significant. MRPD and MRR were significantly related to nutritional and pulmonary function impairment in CF patients. MRPD strongly correlated to maximal respiratory muscle pressures, and MRR strongly correlated to PTI(mus) in patients with CF. These findings suggest that CF patients are at increased risk of respiratory muscle fatigue. Regular determination of MRPD and MRR may be clinically useful in CF patients and help to initiate inspiratory muscle training and noninvasive ventilation.

Comparison of two methods of measurement of maximal respiratory pressures in health and cystic fibrosis

Introduction: Respiratory muscle strength can be assessed by static mouth measurements of maximal inspiratory pressure (Pimax) and maximal expiratory pressure (Pemax). Impaired respiratory muscle strength is common in neuromuscular and obstructive pulmonary disease such as Cystic Fibrosis (CF). Maximal respiratory pressures can easily be measured with a portable manometer on the bedside and in the community. Our objective was to compare maximal respiratory pressures as measured by standard laboratory equipment and the portable mouth pressure meter Micro RPM. Methods: Pimax and Pemax were assessed in 296 healthy subjects and patients with CF with the Micro RPM and standard laboratory equipment. The Micro RPM measures and digitally displays maximal respiratory pressures after averageing over a one second period. Standard laboratory equipment consisted of a differential pressure transducer, whose amplified signals were analyzed by Lab-VIEW software. Each subject performed at least five reproducible maneuvers after familiarizing with the equipment. Results: The Micro RPM accurately measured maximal inspiratory and maximal expiratory pressures both in healthy individuals as well as in patients with CF. Mean difference (standard deviation) of the methods was 1.37 (17.73) cm H2O for Pimax maneuvers and 1.84 (9.09) cm H2O for Pemax maneuvers. Conclusions: The Micro RPM can relia-bly and accurately measure maximal respiratory mouth pressures and its use could be applied both in the clinical and the research setting.

Respiratory muscle function in patients with cystic fibrosis

Respiratory muscle function in patients with cystic fibrosis (CF) can be assessed by measurement of maximal inspiratory pressure (Pimax ), maximal expiratory pressure (Pemax ), and pressure-time index of the respiratory muscles (PTImus ). We investigated the differences in maximal respiratory pressures and PTImus between CF patients with no gross hyperinflation and healthy controls and described the effects of pulmonary function and nutrition impairment on respiratory muscle function in this group of CF patients. Forced expiratory volume in 1 sec (FEV1 ), forced vital capacity (FVC) and maximal expiratory flow between 25% and 75% of VC (MEF25-75 ), body mass index (BMI), upper arm muscle area (UAMA), Pimax , Pemax , and PTImus were assessed in 140 CF patients and in a control group of 140 healthy subjects matched for age and gender. Median Pimax and Pemax were significantly lower in CF patients compared to the controls [Pimax = 74 (57-94) in CF vs. 84 (66-102) in controls, P = 0.009], [Pemax = 71 (50-95) in CF vs. 84 (66-102) in controls, P < 0.001]. Median PTImus in CF patients compared to controls was significantly increased [PTImus = 0.110 (0.076-0.160) in CF vs. 0.094 (0.070-0.137) in controls, P = 0.049] and it was significantly higher in CF patients with impaired pulmonary function. In CF patients, PTImus was significantly negatively related to upper arm muscle area (r = 0.184, P = 0.031). These findings suggest that CF patients with no severe lung disease compared to healthy subjects exhibit impaired respiratory muscle function, while CF patients with impaired pulmonary function and nutrition indices exhibit higher PTImus values.

Assessment of the Respiratory Muscles Function in Chronic Obstructive Pulmonary Disease patients

Chronic Obstructive Pulmonary Disease (COPD) is a public health problem worldwide. It is a polygenic disease and a classical example of gene-environment interaction. Of the many inhalational exposures that may be encountered over a lifetime, only tobacco smoke and occupational dusts and chemicals (vapors, irritants, and fumes) are known to cause COPD on their own. Maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) may be impaired in patients with COPD. Aim of the study: to assess respiratory muscle function in male COPD patients by measuring MIP and MEP values and to identify possible correlation between MIP and MEP and the anthropometric parameters as well as degree of airflow obstruction among COPD patients. Subjects and methods: A case-control study was carried out on 50 COPD male patients and 50 of age and sex matched healthy subjects as a control group. All participants were subjected to assessment of respiratory muscle (RM) strength by MIP and MEP, pulmonary function tests {flow/volume spirometry, and MVV}, as well as the functional exercise capacity (6MWT) and the anthropometric measurements. Results: the values of MIP and MEP in COPD cases were lower than those of the control group with a statistically significant difference. In COPD cases the MIP and MEP were positively correlated with VC%, FEV1\FVC, FEV1%, FVC%, PEF%, MVV%, and 6MWD (p<0.00). Furthermore, COPD patients were subdivided according to the presence of respiratory muscle (RM) affection into two subgroups: Group A (patients with RM affection) and Group B (patients without RM affection). There was a significant difference between the two subgroups concerning smoking index , disease duration, VC% , FVC% ,FEV1\FVC, FEV1%, PEF%, MVV%, and 6MWD (P< 0.05). Conclusion: RM is affected in patients with COPD. Measurement of MIP and MEP indicates the state of RM which is related to smoking index, disease duration, and spirometric-indices (VC%, FVC%, FEV1\FVC, FEV1%, PEF%, and MVV %). Recommendation: Health care workers involved in the diagnosis and management of COPD patients especially those with severe airflow obstruction should consider the possibility of RM deterioration and should have an access to RM function assessment.

Extubation process in bed-ridden elderly intensive care patients receiving inspiratory muscle training: a randomized clinical trial

BackgroundThe purpose of this study was to evaluate the extubation process in bed-ridden elderly intensive care patients receiving inspiratory muscle training (IMT) and identify predictors of successful weaning.MethodsTwenty-eight elderly intubated patients in an intensive care unit were randomly assigned to an experimental group (n = 14) that received conventional physiotherapy plus IMT with a Threshold IMT® device or to a control group (n = 14) that received only conventional physiotherapy. The experimental protocol for muscle training consisted of an initial load of 30% maximum inspiratory pressure, which was increased by 10% daily. The training was administered for 5 minutes, twice daily, 7 days a week, with supplemental oxygen from the beginning of weaning until extubation. Successful extubation was defined by the ventilation time measurement with noninvasive positive pressure. A vacuum manometer was used for measurement of maximum inspiratory pressure, and the patients’ Tobin index values were measured using a ventilometer.ResultsThe maximum inspiratory pressure increased significantly (by 7 cm H2O, 95% confidence interval [CI] 4–10), and the Tobin index decreased significantly (by 16 breaths/ min/L, 95% CI −26 to 6) in the experimental group compared with the control group. The Chi-squared distribution did not indicate a significant difference in weaning success between the groups (χ2 = 1.47; P = 0.20). However, a comparison of noninvasive positive pressure time dependence indicated a significantly lower value for the experimental group (P = 0.0001; 95% CI 13.08–18.06). The receiver-operating characteristic curve showed an area beneath the curve of 0.877 ± 0.06 for the Tobin index and 0.845 ± 0.07 for maximum inspiratory pressure.ConclusionThe IMT intervention significantly increased maximum inspiratory pressure and significantly reduced the Tobin index; both measures are considered to be good extubation indices. IMT was associated with a reduction in noninvasive positive pressure time in the experimental group.

Evaluation of maximal inspiratory and sniff nasal inspiratory pressures in pre- and postoperative myocardial revascularization

The objective of this study was to evaluate and correlate inspiratory muscle strength using maximal inspiratory pressure (MIP) and sniff nasal inspiratory pressure (Pnsn) in patients with coronary artery disease in pre- and postoperative of myocardial revascularization surgery. Thirty-eight men were studied, divided into a control group (CG) comprised of healthy individuals (n=18), age 55.52 ± 7.8 years and a myocardial revascularization group (MRG), comprised of patients with coronary artery disease submitted to myocardial revascularization (n=20), age 58.44 ± 9.3 years. All volunteers were submitted to MIP and Pnsn measurement, and the MRG was evaluated in the preoperative period and on the first postoperative day (PO1). MRG presented MIP (80.60 ± 26.60 cmH2O) and Pnsn (74.70 ± 31.80 cmH2O) values inferior to CG (MIP: 112.22 ± 32.00 cmH2O; Pnsn: 103.70 ± 34.10 cmH2O), and there was significant reduction of these values on PO1 (MIP: 40.05 ± 15.70 cmH2O; Pnsn: 40.05 ± 16.60 cmH2O). There was correlation and concordance between evaluation methods in both groups studied, as well as in pre- and postoperative MRG conditions. The results showed that the studied patients presented reduced MIP and Pnsn pre- and post-operative myocardial revascularization. Also, the Pnsn correlated with MIP and can be considered suitable for assessing inspiratory muscle strength in this population.

Reference values of respiratory and peripheral muscle function in rats

Skeletal muscle dysfunction is a common systemic manifestation in several prevalent diseases. Predictive values are useful tools for the diagnosis and prognosis of diseases. In experimental animals, no reference values of muscle function evaluation have been so far reported. The objective was to obtain predictive values of maximal inspiratory pressure (MIP) and grip strength measurements in healthy rats. In 70 healthy rats, MIP and grip strength were measured in vivo weekly for five consecutive weeks using non-invasive methodologies. Three ranges of rat body weights (250-299, 300-349 and 350-399 g) and lengths (37.0-41.0, 41.1-42.0 and 42.1-44.0 cm) were established. MIP and grip strength measurements falling within the ranges of weight 350-399 and 300-349 g and length 42.1-44.0 cm were significantly greater than values falling within 250-299 g and 37.0-41.0 cm ranges respectively. Specific weight- and length-percentile distributions for MIP and grip strength measurements were calculated. As significant direct correlations were observed between rat weights and lengths and either MIP or grip strength measurements, regression equations relating all these variables were also determined. Skeletal muscle dysfunction is frequently associated with highly prevalent conditions. The significant predictive equations described for both MIP and grip strength measurements will enable scientists to better estimate the respiratory and peripheral muscle dysfunctions of laboratory animals, especially when conducting follow-up and/or intervention investigations.

Acute Cardiorespiratory Responses to Inspiratory Pressure Threshold Loading

We tested the acute responses to differing pressure threshold inspiratory loading intensities in well-trained rowers. The purpose of this study was to evaluate 1) how the magnitude of inspiratory pressure threshold loading influences repetition maximum (RM), tidal volume (VT), and external work undertaken by the inspiratory muscle; and 2) whether the inspiratory muscle metaboreflex is activated during acute inspiratory pressure threshold loading. Eight males participated in seven trials. Baseline measurements of maximal inspiratory pressure (PImax), resting tidal volume (VT), and forced vital capacity (FVC) were made. During the remaining sessions, participants undertook a series of resistive inspiratory breathing tasks at loads corresponding to 50%, 60%, 70%, 80%, and 90% of PImax using a pressure threshold inspiratory muscle trainer. The number of repetitions completed at each load, VT, heart rate (fc), and measures of arterial blood pressure was assessed continuously during each trial. A standardized cutoff of 10% FVC was used to define the RM, which decreased as loading intensity increased (P < 0.05). This response was nonlinear, with an abrupt decrease in RM occurring at loads > or =70% of PImax. The most commonly used inspiratory muscle training regimen of 30RM corresponded to 62.5% +/- 4.6% of PImax and also resulted in the highest external work output. Tidal volume (VT) decreased significantly over time at 60%, 70%, and 80% of PImax (P < 0.05), as did the amount of external work completed (P<0.05). Although all loads elicited a sustained increase in fc, only the 60% load elicited a sustained rise in mean arterial blood pressure (P = 0.016), diastolic blood pressure (P = 0.015), and systolic blood pressure (P = 0.002), providing evidence for a metaboreflex response at this load.

Respiratory muscle pressures in non-CF bronchiectasis: Repeatability and reliability

Respiratory muscle strength is used diagnostically in clinical practice and as an outcome measure in clinical trials in various chronic lung diseases. There is limited data on its repeatability in people with non-CF bronchiectasis. The aim of the present study was to assess the repeatability of maximal inspiratory (P( I)max) and expiratory pressures (P(E)max) in a group of patients with stable, moderate-to-severe non-CF bronchiectasis. Twenty participants with stable moderate-to-severe non-CF bronchiectasis were recruited. Respiratory muscle strength measurements (three maximal inspiratory and expiratory pressures) were made on 2 separate days. A standard protocol was used, including practice tests, before obtaining three technically acceptable and reproducible readings with a difference of 10% or less between values. ClinicalTrials.gov: NCT00487149. The mean (SD) age of the non-CF bronchiectasis group was 63 (9) years. Maximal inspiratory pressures were repeatable with mean (SD) for highest P(I)max, Test 1 and Test 2, 75.90 (20) and 79.40 (19) cmH(2)O, and limits of agreement (mean difference +/- 2SD) -3.50 +/- 20 cmH(2)O, (p = 0.14). Maximal expiratory pressures differed significantly with mean (SD) for highest P(E)max, Test 1 and Test 2, 102.25 (27) and 112.30 (32) cmH(2)O, and limits of agreement (mean difference +/- 2SD) -10.10 +/- 35 cmH(2)O, (p = 0.02). The intraclass correlation coefficient (95% CI) for highest P(I)max and P(E)max was 0.93 (95% CI 0.82 to 0.97) and 0.90 (95% CI 0.76 to 0.96), respectively. Maximal inspiratory pressure measurements were repeatable during a period of clinical stability in moderate-to-severe non-CF bronchiectasis, suggesting this may be a useful outcome measure in non-CF bronchiectasis. Once a baseline has been established, a second visit is not required. P(E)max was not a repeatable measure and further study is necessary to ascertain how much practice testing is required to obtain an accurate value.

Comparação e efeitos de dois diferentes tempos de oclusão da via aérea durante a mensuração da pressão inspiratória máxima em pacientes neurológicos na unidade de terapia intensiva de pacientes adultos

To verify if the maximal inspiratory pressure values with 40 seconds occlusion time are greater than with the 20 seconds occlusion time, and the impacts on the following patient's physiological variables: respiratory rate, pulse oxygen saturation, heart rate and blood pressure, before and after the measurements. This was a transversal prospective randomized study. Fifty-one patients underwent maximal inspiratory pressure measurement, measured by one single investigator. The manometer was calibrated before each measurement, and then connected to the adapter and this to the unidirectional valve inspiratory branch for 20 or 40 seconds. The values with 40 seconds occlusion (57.6 ± 23.4 cmH2O) were significantly higher than the measurements taken with 20 seconds occlusion (40.5 ± 23.4 cmH2O; p=0.0001). The variables changes between the before and after measurement respiratory and hemodynamic parameters monitoring showed: heart rate variation for the 20 seconds occlusion 5.13 ± 8.56 beats per minute and after 40 seconds occlusion 7.94 ± 12.05 beats per minute (p = 0.053), versus baseline. The mean blood pressure change for 20 seconds occlusion was 9.29 ± 13.35 mmHg and for 40 seconds occlusion 15.52 ± 2.91 mmHg (p=0.021). The oxygen saturation change for 20 seconds occlusion was 1.66 ± 12.66%, and for 40 seconds 4.21 ± 5.53% (p=0.0001). The respiratory rate change for 20 seconds occlusion was 6.68 ± 12.66 movements per minute and for 40 seconds 6.94 ± 6.01 (p=0.883). The measurement of maximal inspiratory pressure using a longer occlusion (40 seconds) produced higher values, without triggering clinically significant stress according to the selected variables.

Maksimum İnspiratuar Basınç: Kronik Obstrüktif Akciğer Hastalığı Olan Hastalarda İnvaziv Ventilatörden Ayırma Başarısını Tahminde Yardımcı Bir Parametre Olabilir mi?

Objective: To evaluate the predictive value of maximum inspiratory pressure (MIP) besides rapid and shallow breathing index (RSBI) in the weaning of chronic obstructive pulmonary disease (COPD) patients. Material and Methods: Fifty-six COPD patients with acute exacerbation and type II respiratory failure requiring invasive mechanical ventilation for more than 24 hours were enrolled in this study. Extubation was planned if the patients tolerated pressure support mode for at least two hours and spontaneous breathing during a 30 minutes T-piece trial. Breathing frequency, exhaled tidal volume, rapid and shallow breathing index (RSBI), minute ventilation (Vmin), MIP and vital capacity measurements were recorded prior to extubation. Patients were divided into two groups according to weaning success (WS) and failure. WS was defined as 48 hours of independence from mechanical ventilation after extubation. Results: Although RSBI values between two groups were not significantly different, there were statistically significant differences between the two groups in terms of MIP (30 vs 18 cmH2O; p= 0.008) and Vmin (10.40 vs 8.25; p= 0.032). Patients with a MIP value greater than or equal to 25 cm H2O had greater WS when compared to those with values lower than 25 cm H2O. Conclusion: RSBI alone seems not reliable enough to predict weaning outcome in COPD patients with type II respiratory failure due to acute exacerbation. Supported with MIP, better results may be achieved to predict weaning outcome.

Mouth and Nasal Inspiratory Pressure: Learning Effect and Reproducibility in Healthy Adults

Background: Inspiratory muscle strength measurements have become a cornerstone in monitoring neuromuscular disorders. Usually, sniff nasal inspiratory pressure (SNIP) and maximal inspiratory pressure (MIP) are performed. To our knowledge the session-to-session learning effect has rarely been evaluated for MIP performance and has never been done for SNIP performance. Objectives: We hypothesized that the sniff manoeuvre was natural and did not need to be learned, whereas the Muller manoeuvre, used for MIP measurement, was an isometric contraction which needed to be learned because it is rarely performed in real life conditions. This hypothesis suggests that from the first session and continuing through a subsequent one, the maximal SNIP value and the number of sniff trials necessary to attain it are more reproducible than the maximal MIP value and the number of Muller manoeuvre trials necessary to attain it. Methods: Seventy-one healthy subjects were included. SNIP and MIP manoeuvres were repeated 12 and 6 times, respectively, per week during 2 sessions a week apart. Results: We observed a session effect on MIP but not on SNIP. Maximal value for MIP was higher during the second session, whereas SNIP maximal value did not increase during the second session. The number of trials needed to obtain the maximal value for MIP was lower during the second session whereas it was not different for SNIP. Conclusions: SNIP is less sensitive to a learning effect than is MIP. It requires only a routine warm-up. We suggest that SNIP is preferable to MIP for repeated measurement of inspiratory muscle performance.