Cough flows as a criterion for decannulation of autonomously breathing patients with tracheostomy tubes.

BACKGROUND: Adequate cough or exsufflation flow can indicate an option for safe tracheostomy decannulation to noninvasive management. Cough peak flow via the upper airways with the tube capped is an outcome predictor for decannulation readiness in patients with neuromuscular impairment. However, this threshold value is typically measured with tracheotomy tube removed, which is not acceptable culturally in China. The aim of this study was to assess the feasibility and safety of using cough flow measured with tracheostomy tube and speaking valve (CFSV) > 100 L/min as a cutoff value for decannulation. STUDY DESIGN: Prospective observational study conducted between January 2019 and September 2022 in a tertiary rehabilitation hospital. METHODS: Patients with prolonged tracheostomy tube placement were referred for screening. Each patient was assessed using a standardized tracheostomy decannulation protocol, in which CFSV greater than 100 L/min indicated that the patients' cough ability was sufficient for decannulation. Patients whose CFSV matched the threshold value and other protocol criteria were decannulated, and the reintubation and mortality rates were followed-up for 6 months. RESULTS: A total of 218 patients were screened and 193 patients were included. A total of 105 patients underwent decannulation, 103 patients were decannulated successfully, and 2 patients decannulated failure, required reinsertion of the tracheostomy tube within 48 h (failure rate 1.9%). Three patients required reinsertion or translaryngeal intubation within 6 months. CONCLUSIONS: CFSV greater than 100 L/min could be a reliable threshold value for successful decannulation in patients with various primary diseases with a tracheostomy tube. TRIAL REGISTRATION: This observational study was not registered online.

Effect of Inspiratory Muscle Training on Cough Strength in Older People With Frailty: A Single-Blind Randomized Controlled Trial.

OBJECTIVE: To investigate the effect of inspiratory muscle training (IMT) on cough strength in older people with frailty. DESIGN: Single-blind randomized controlled trial. SETTING: Day health care centers at 2 sites. PARTICIPANTS: Older people with frailty (N=60). INTERVENTIONS: Eligible people were randomly assigned to receive IMT program in addition to general exercise training (IMT group), or general exercise training alone (control group). The IMT group performed training using a threshold IMT device with the load set at 30% of maximum inspiratory mouth pressure in addition to the general exercise training program throughout the 8 weeks. The IMT took place twice a day and each session consisted of 30 breaths. MAIN OUTCOME MEASURES: Primary outcome was cough strength, measured as the cough peak flow (CPF), at the beginning and the end of the program. RESULTS: Data from 52 participants (26 in each group) were available for the analysis. The mean age was 82.6 years; 33% were men. The change in CPF at the end of the program was 28.7±44.4 L/min in the IMT group and -7.4±26.6 L/min in the control group. A linear regression model showed that the presence or absence of IMT was associated with changes in CPF (mean difference between groups, 36.3; 95% confidence interval, 16.7-55.9; effect size, 0.99). CONCLUSIONS: IMT may be a useful intervention to improve cough strength in frail older people.

Analysis of Dysphagia and Cough Strength in Patients with Unilateral Vocal Fold Paralysis.

The association between swallowing function and cough strength in patients with unilateral vocal fold paralysis (UVFP) is unknown. We evaluated the relationship between voluntary cough strength and dysphagia among patients with UVFP (UVFP group) by comparing their data with that of corresponding healthy participants (healthy control [HC] group) in a prospective observational study. From February 1st, 2018 to March 30th, 2019, we recruited patients with a voice disorder due to UVFP, who were referred to our university hospital. Patients with a history of laryngeal surgery, vagal nerve paralysis, or cardiac and respiratory failure were excluded. Descriptive and clinical data regarding swallowing, voice, and cough peak flow (CPF) were collected as a measure of cough strength. The UVFP group comprised six women and seven men (median age, 68.0 years), and the HC group comprised six women and eight men (median age 65.5 years). The groups differed significantly in the Eating Assessment Tool (EAT)-10 scores and CPF rates (P < 0.001). Among patients with UVFP, 84.6% had an abnormal EAT-10 score of ≥ 3. Additionally, 16.7% of the patients exhibited liquid aspiration with contrast medium on a videofluorographic swallowing study (VFSS). There was no correlation between the CPF values, EAT-10 scores, or the VFSS results. Therefore, patients with severe UVFP, whose condition had been fixed, had difficulties when swallowing (85% of cases), and some even presented with aspiration on VFSS (20% of cases), while receiving a regular diet.

[Relationship between cough peak flow and onset of pneumonia in residents of geriatric health services facilities].

AIM: Sputum expectoration is associated with cough strength, which can be evaluated by cough peak flow (CPF). Since sputum expectoration can be difficult for patients with reduced CPF, they are more likely to have risk factors for pneumonia. We conducted a study to clarify factors contributing to CPF in residents of geriatric health services facilities and to assess the relationship between CPF and the onset of pneumonia. METHODS: We included 41 male residents of geriatric health services facilities from September to the middle of October 2018. We recorded each subject's age, body mass index (BMI), Performance Status (PS), nursing care level, Functional Independence Measure (FIM), pulse rate, percutaneous arterial oxygen saturation (SpO2), hand grip strength, Charlson comorbidity index, underlying diseases and rales upon auscultation. We also used Pearson's correlation analysis to analyze the relationship between CPF and the above factors. Subjects were assigned to 2 groups according to median CPF to determine the between-group relationships of these factors. Finally, subjects were followed up for 6 to 11 months after CPF measurement to confirm whether or not they developed pneumonia. RESULTS: CPF was positively correlated with BMI (nutritional parameter), hand grip strength (index of systemic muscular strength), and SpO2 The median CPF was 240 L/minute, and subjects were divided into 2 groups based on this valus: CPF ≤240 L/minute group (n=21) and CPF >240 L/minute group (n=20). Subjects in the CPF ≤240 L/minute group demonstrated lower BMI and hand grip strength but more pronounced rales upon auscultation. No statistically significant difference was observed between the 2 groups during the 6-month folloe-up. However, the 11-month follow-up demonstrated a higher incidence of pneumonia in the CPF ≤240 L/minute group. CONCLUSION: The above findings suggest that subjects with reduced CPF are more likely to develop pneumonia. To increase CPF, muscle rehabilitation therapy and nutrition management should be provided to residents of geriatric health services facilities to prevent pneumonia.

Cough peak flow decline rate predicts survival in patients with amyotrophic lateral sclerosis.

INTRODUCTION: In this study we investigated the prognostic significance of cough peak flow (CPF) decline rate in patients with amyotrophic lateral sclerosis (ALS). METHODS: Thirty-four patients with ALS participated in our investigation. We examined CPF, forced vital capacity (FVC), body mass index, and the revised ALS Functional Rating Scale (ALSFRS-R), and followed patients to death, tracheostomy, or non-invasive ventilator dependency. We analyzed the relationship between the rate of decline of each parameter and survival prognosis. RESULTS: The CPF decline rate significantly correlated with the decline rates of the ALSFRS-R bulbar score (P < 0.0001) and FVC (P < 0.0001). Patients with a CPF decline rate ≥25% had shorter overall survival (P < 0.0001). Cox model multivariate analyses showed that the CPF decline rate was an independent prognostic factor for survival (P = 0.021). DISCUSSION: The CPF decline rate reflects the progression of bulbar and respiratory dysfunction and predicts survival. Muscle Nerve 59:168-173, 2019.

A Mobile Cough Strength Evaluation Device Using Cough Sounds.

Although cough peak flow (CPF) is an important measurement for evaluating the risk of cough dysfunction, some patients cannot use conventional measurement instruments, such as spirometers, because of the configurational burden of the instruments. Therefore, we previously developed a cough strength estimation method using cough sounds based on a simple acoustic and aerodynamic model. However, the previous model did not consider age or have a user interface for practical application. This study clarifies the cough strength prediction accuracy using an improved model in young and elderly participants. Additionally, a user interface for mobile devices was developed to record cough sounds and estimate cough strength using the proposed method. We then performed experiments on 33 young participants (21.3 ± 0.4 years) and 25 elderly participants (80.4 ± 6.1 years) to test the effect of age on the CPF estimation accuracy. The percentage error between the measured and estimated CPFs was approximately 6.19%. In addition, among the elderly participants, the current model improved the estimation accuracy of the previous model by a percentage error of approximately 6.5% (p < 0.001). Furthermore, Bland-Altman analysis demonstrated no systematic error between the measured and estimated CPFs. These results suggest that the developed device can be applied for daily CPF measurements in clinical practice.

Estimation of Cough Peak Flow Using Cough Sounds.

Cough peak flow (CPF) is a measurement for evaluating the risk of cough dysfunction and can be measured using various devices, such as spirometers. However, complex device setup and the face mask required to be firmly attached to the mouth impose burdens on both patients and their caregivers. Therefore, this study develops a novel cough strength evaluation method using cough sounds. This paper presents an exponential model to estimate CPF from the cough peak sound pressure level (CPSL). We investigated the relationship between cough sounds and cough flows and the effects of a measurement condition of cough sound, microphone type and participant's height and gender on CPF estimation accuracy. The results confirmed that the proposed model estimated CPF with a high accuracy. The absolute error between CPFs and estimated CPFs were significantly lower when the microphone distance from the participant's mouth was within 30 cm than when the distance exceeded 30 cm. Analysis of the model parameters showed that the estimation accuracy was not affected by participant's height or gender. These results indicate that the proposed model has the potential to improve the feasibility of measuring and assessing CPF.

Reliability and validity of cough peak flow measurements in myasthenia gravis.

Decreased cough strength in myasthenia gravis (MG) leads to aspiration and increases the risk of MG crisis. The aim of this study was to clarify the reliability and validity of cough peak flow (CPF) measurements in MG. A total of 26 patients with MG who underwent CPF measurements using the peak flow meter by themselves were included. MG symptoms were evaluated by pulmonary function tests and clinical MG assessment scales before and after immune-treatments. The relationship between CPF and pulmonary function tests and MG comprehensive were assessed. The cut-off value of CPF for aspiration risk was determined and the area under the curve (AUC) was calculated. The intraclass correlation coefficient was more than 0.95 for pre-and post-treatment. Positive correlations were found between CPF and almost all spirometric values as well as between the differences of pre-and post-treatment in CPF and quantitative myasthenia gravis score. The CPF for identifying the aspiration risk was used to calculate the CPF cut-off value of 205 L/min with a sensitivity of 0.77, specificity of 0.90, and AUC of 0.85. The CPF, a convenient measure by patients themselves, has a high reliability in patients with MG, and is a useful biomarker reflecting MG symptoms.

Correlation between Respiratory Dysfunction and Dysphagia in Individuals with Acute Traumatic Cervical Spinal Cord Injury.

Introduction: Aspiration pneumonia is one of the most frequent and fatal life-threatening complications among individuals with acute traumatic cervical spinal cord injury (CSCI). However, the mechanism of dysphagia among individuals with CSCI is not well understood. Morbidity and mortality associated with CSCI may result from the interplay between respiratory dysfunction and dysphagia. This study aimed to elucidate the effect of respiratory dysfunction on the swallowing function of individuals with acute traumatic CSCI. Methods: A prospective cohort study was conducted involving 54 individuals with acute traumatic CSCI who were admitted within 2 weeks following injury. Dysphagia was evaluated using the Dysphagia Severity Scale (DSS) and the Functional Oral Intake Scale (FOIS). Respiratory function was evaluated by measuring the cough peak flow (CPF), forced expiratory volume in 1 s (FEV1.0), FEV1.0/forced vital capacity (FEV1.0%), and percent vital capacity (%VC). We recorded these parameters at weeks 2, 4, 8, and 12 following injury and analyzed pertinent changes over time and significant correlations. Results: Among 54 individuals (46 men and 8 women) recruited in this study, 48 (88.9%) had restrictive ventilatory impairment and 17 (31.5%) had severe dysphagia (DSS level 1-4) 2 weeks following injury. However, respiratory function and swallowing function significantly improved thereafter. CPF, FEV1.0, and %VC were significantly correlated with the severity of dysphagia during each period. Conclusions: Restrictive ventilatory impairment, poor cough force, and dysphagia are closely related, and the evaluation of respiratory function plays an important role in evaluating dysphagia.

Mechanical Insufflation-Exsufflation: Considerations for Improving Clinical Practice.

The provision of mechanical insufflation-exsufflation (MI-E) devices to enhance cough efficacy is increasing. Typically, MI-E devices are used to augment cough in patients with neuromuscular disorders but also in patients who are weak in an acute care setting. Despite a growing evidence base for the use of these devices, there are barriers to the provision of MI-E, including clinician lack of knowledge and confidence. Enhancing clinician education and confidence is key. Individualized or protocolized approaches can be used to initiate MI-E. Evaluation of MI-E efficacy is critical. One method to evaluate effectiveness of MI-E is the MI-E-assisted cough peak flow (CPF). However, this should always be considered alongside other factors discussed in this review. The purpose of this review is to increase the theoretical understanding of the provision and evaluation of MI-E and provide insight into how this knowledge can be applied into clinical practice. Approaches to initiation and titration can be selected based on the clinical situation, patient diagnosis (including and beyond neuromuscular disorders), and clinician's confidence.

Mechanical Insufflation-Exsufflation Implementation and Management, Aided by Graphics Analysis.

Mechanical insufflation-exsufflation (MIE) facilitates airway clearance to mitigate respiratory infection, decompensation, and ultimately the need for intubation and placement of a tracheostomy tube. Despite widespread adoption as a respiratory support intervention for motor neuron disease, muscular dystrophy, spinal cord injury, and other diseases associated with ventilatory pump failure and ineffective cough peak flow, there is debate in the clinical community about how to optimize settings when MIE is implemented. This article will demonstrate the clinical utility of MIE graphics in titrating the initial MIE settings, guiding upper airway and lung protective strategies and providing insight to clinicians for ongoing clinical management.

[Can cough peak flow be used to assess cough capacity in severe obstructive respiratory diseases?] / ¿Se puede utilizar la determinación del pico flujo de tos para valorar la capacidad tusígena en enfermedades respiratorias obstructivas graves?

INTRODUCTION: Cough capacity is assessed by measuring cough peak flow (CPF). However, this assessment could be altered by obstructive airway diseases. The aim was to assess measurement of cough capacity by CPF in patients with chronic obstructive pulmonary disease (COPD), as well as correlations with pulmonary, respiratory muscle, and oropharyngeal function. METHODS: Patients with COPD, and with neuromuscular disease, were selected as well as healthy subjects who had undergone respiratory muscle strength measurement in a healthcare setting. From this population, respiratory function values and lung and oropharyngeal muscle function were analysed. A subgroup of COPD patients underwent a videofluoroscopic swallow study. RESULTS: Three hundred and seven subjects were included (59.3% COPD, 38.4% neuromuscular diseases, and 2.3% healthy). CPF was found to be statistically significantly decreased in the COPD group compared to both the healthy and neuromuscular disease groups. Of the COPD patients, 70% had a pathological decrease in CPF. There was only a direct correlation between CPF with the degree of bronchial obstruction and expiratory muscle strength. No alteration of inspiratory or oropharyngeal muscle function was found. CONCLUSIONS: The use of CPF in COPD patients does not reflect cough capacity as it is influenced by the degree of bronchial obstruction. Therefore, new diagnostic tests to measure cough capacity should be considered, especially in patients with coexisting neuromuscular diseases and severe bronchial obstructive disease.

The use of cough peak flow in the assessment of respiratory function in clinical practice- A narrative literature review.

Cough peak flow (CPF) is a useful clinical measurement to assess neuromuscular activity and effective coordination, yet it is rarely used in clinical practice outside of the management of patients with neuromuscular disorders. A CPF of above 160 L/min is required for an effective cough and less than 270 L/min is associated with increased secretion retention and risk of infection. Reduced CPF can be due to a number of mechanisms including reduced respiratory muscle strength, lack of co-ordination of glottic closure and opening, airway obstruction and, age and activity related changes. CPF has been shown to be correlated with other measures of pulmonary function in neuromuscular disorders and in predicting extubation failure. Patients with Parkinson's disease have a reduced CPF even at early stages and dedicated expiratory muscle strength training (EMST) has been shown to be beneficial. Sequential studies in patient with stroke-associated dysphagia reported CPF was correlated with risk of respiratory infection and results of formal swallow assessments. Age-related changes in expiratory muscle strength and lung physiology contribute to increased risk of aspiration and pneumonia. EMST may have a role in healthy adults to improve muscle strength and effective cough, potentially reducing risk of respiratory tract infections even in the absence of disease. CPF has potential to be extremely useful in clinical practice in a wide spectrum of diseases. In particular, studies in patients with frequent exacerbations of COPD and recurrent pneumonia are currently lacking and would be of benefit to explore the relationship between ineffective cough and recurrent infection.

Expiratory muscle strength training improves measures of pressure generation and cough strength in a patient with myotonic dystrophy type 1.

Expiratory muscle strength training (EMST) exercise programmes aim to improve respiratory function by increasing the force generating capability of expiratory muscles by resistance training. In neuromuscular conditions, in which cough flow generation is often decreased, there is increasing interest in EMST as a therapeutic intervention. We present data showing efficacy of EMST in a patient with adult onset Myotonic Dystrophy Type 1 (DM1). A domiciliary training programme (5 days per week over 32 weeks) resulted in increases in maximum expiratory mouth pressure (from 15 cmH2O to 38 cmH2O) and peak cough flow (300 L/min to 390 L/min). Improvements were also seen in maximum inspiratory mouth pressure (26 cmH2O to 52 cmH2O) and sniff nasal inspiratory pressure (40 cmH2O to 69 cmH2O). No changes were detected in speech or swallowing. This novel study demonstrates that cough flow generation in DM1 may be increased by a programme of expiratory muscle training. A clinical trial of EMST in DM1 is warranted.

Cough peak flow with different mechanically assisted coughing approaches under different conditions in patients with neuromuscular disorders.

PURPOSE: Mechanically assisted coughing (MAC) is an airway clearance method in which the thorax/abdomen is compressed in synchronization with mechanical insufflation-exsufflation (MI-E). MAC can be performed with manual assistance at the upper thorax (MAC-UT), lower thorax (MAC-LT), and upper thorax + abdomen (MAC-UT/A). This study aimed to determine the most effective approach under different conditions (air stacking or tracheostomy) in patients with neuromuscular disorders (NMDs). METHODS: The study included 34 patients with NMDs. The patients were categorized into air stacking group (n=15), no air stacking group (n=9), and tracheostomy/tracheostomy positive-pressure ventilation (TPPV) group (n=10). RESULTS: In each group, the cough peak flow (CPF) at 75% of the forced vital capacity (V̇75), V̇50, V̇25, and V̇10 were investigated during the approaches. In the air stacking group, the CPF was higher with MAC-UT, MAC-LT, and MAC-UT/A than with MI-E (p < 0.05). Additionally, V̇75 was higher with MAC-LT and MAC-UT/A than with MI-E (p < 0.05 and p < 0.01, respectively). In the no air stacking group, V̇75 was higher with MAC-UT/A than with MI-E (p < 0.05). In the tracheotomy/TPPV group, there were no significant differences. CONCLUSIONS: MAC approaches, especially MAC-LT and MAC-UT/A, are preferred in air stacking patients. However, in tracheostomy/TPPV patients, the CPF might not increase with MAC.

Weaning attempts, cough strength and albumin are independent risk factors of reintubation in medical patients.

BACKGROUND: Reintubation is associated with increased hospital mortality. It is necessary to identify risk factors associated with reintubation. METHODS: A prospective observational study was performed in a respiratory intensive care unit. Medical patients who successfully completed a spontaneous breathing trial (SBT) were enrolled. Before extubation, age, gender, vital signs, acute physiology and chronic health evaluation II score, SBT attempts, cough peak flow, arterial blood gas tests and albumin were recorded. RESULTS: We enrolled 139 patients. Of these, 22 (15.8%) patients experienced reintubation within 72 hours after extubation. SBT attempts (odds ratio [OR] = 1.446, 95% confidence interval [CI]: 1.095-1.910), cough peak flow (OR = 0.975, 95% CI: 0.956-0.994) and albumin (OR = 0.847, 95% CI: 0.752-0.954) were independent risk factors for reintubation. In patients with 1, 2 and ≥3 SBT attempts, reintubation rates were 7.3%, 21.1% and 45.8%, respectively (P < .01). In patients with cough peak flow ≤60, 61-89 and ≥90 L/min, reintubation rates were 29.4%, 16.7% and 1.9%, respectively (P < .01). In patients with albumin ≤25, 26-30 and ≥31 g/L, reintubation rates were 32.4%, 11.1% and 9.8%, respectively (P = .01). CONCLUSIONS: Multiple SBT attempts, weak cough and low albumin were associated with increased reintubation in medical patients. This study provides information for clinical practitioners in the consideration of patient extubation.

Approaches to Cough Peak Flow Measurement With Duchenne Muscular Dystrophy.

BACKGROUND: Manually-assisted coughing and mechanical insufflation-exsufflation (MI-E) are commonly used in patients with Duchenne muscular dystrophy (DMD). Few studies have compared cough peak flow (CPF) with manually-assisted coughing to other methods, such as MI-E + manually-assisted coughing. In addition, few studies have reported the reliability of the measured CPF values. This study aimed to compare CPF with different cough-assistance methods and to examine the reliability of CPF data. METHODS: The study included 12 subjects with DMD (mean age, 34 ± 8 y). CPF, CPF + manually-assisted coughing (assisted CPF), maximum insufflation capacity (MIC) + CPF (MIC-CPF), MIC + manually-assisted coughing (MIC+assisted CPF), MI-E (MI-E-CPF), and MI-E + assisted CPF were measured. A spirometer was used to compare CPF measurements obtained with each of the cough-assist techniques. The reliability of the measured CPF values was analyzed using Bland-Altman analysis. RESULTS: CPF was 59 ± 34 L/min, assisted CPF was 113 ± 32 L/min, MIC-CPF was 170 ± 30 L/min, MIC+assisted CPF was 224 ± 62 L/min, MI-E-CPF was 199 ± 40 L/min, and MI-E + assisted CPF was 240 ± 38 L/min. A fixed and proportional bias was found in the CPF measurements made with the peak flow meter and the spirometer. The average 95% CI in the difference between peak flow meter, MI-E, and CPF obtained using the spirometer were -7.45 to -1.95 and -1.45 to 4.95, respectively. Test for correlation was r = 0.54 (P < .001) for CPF (peak flow meter) and CPF (spirometer) and r = 0.17 (P = .17) in CPF (MI-E) and CPF (spirometer), respectively. CONCLUSION: MI-E + assisted CPF was the highest. The CPF measured with the peak flow meter suggested underestimation.

Teaching Manually Assisted Cough to Caregivers of Children With Neuromuscular Disease.

BACKGROUND: Cough augmentation techniques are taught by health-care providers to improve secretion clearance and to help prevent respiratory infections in children with neuromuscular disease. There is some evidence of the effectiveness of a manually assisted cough when applied by health-care providers. However, it is unknown whether parents and caregivers may also be effective in applying manually assisted cough. The aim of this study was to evaluate whether parents and caregivers are effective at applying a manually assisted cough to a child with neuromuscular disease after being taught by a health-care provider. METHODS: For this prospective cohort study, children and their parents or caregivers were recruited from neuromuscular clinics in the Sydney Children's Hospitals Network. Cough peak flow was the outcome measure for the strength of the child's cough. Children were eligible to participate if their unassisted cough peak flow at baseline was <270 L/min. Parents and caregivers were taught a manually assisted cough by a physiotherapist before being measured. The cough peak flow was measured in the following order: (1) during an unassisted cough as baseline, (2) during a manually assisted cough performed by a physiotherapist, (3) during a manually assisted cough performed by a parent or caregiver, and (4) during an unassisted cough after intervention. RESULTS: Twenty-eight children (24 boys, 4 girls; mean ± SD age, 12 ± 3 y) completed the study. No clinically or statistically significant changes were found in the cough peak flow after the application of a manually assisted cough by parents or caregivers (95% CI -11 to 11 L/min) or by physiotherapists (95% CI -6 to 14 L/min). CONCLUSIONS: Parents and caregivers and health-care providers were ineffective at increasing cough peak flow in children with neuromuscular weakness when applying a manually assisted cough. A single training session was insufficient for a parent or caregiver to be able to apply a manually assisted cough effectively on his or her child with neuromuscular weakness. Further research is warranted to guide recommendations on how best to equip parents and caregivers with the skills to help manage children with neuromuscular disease.

Use of Cough Peak Flow Measured by a Ventilator to Predict Re-Intubation When a Spirometer Is Unavailable.

BACKGROUND: A ventilator includes the function to measure flow velocity. We aimed to compare the predictive accuracy for re-intubation diagnosed by cough peak flow (CPF) measured by a spirometer and a ventilator. METHODS: Endotracheally intubated subjects who passed a spontaneous breathing trial were enrolled. Before extubation, CPF was measured by a spirometer and a ventilator, respectively. Re-intubation was recorded at 72 h after extubation. RESULTS: A total of 126 subjects were enrolled. Among them, 15 subjects (12%) experienced re-intubation. CPF was lower in re-intubated subjects than those without re-intubation (measured by a spirometer: 54 ± 30 L/min vs 86 ± 37 L/min, P < .001; and measured by a ventilator: 50 ± 22 L/min vs 80 ± 26 L/min, P < .001). CPF measured by a spirometer and a ventilator had similar area under the curve of receiver operating characteristic (0.79 vs 0.83, P = .26). When a CPF of 56.4 L/min was measured by a spirometer as cutoff value, the sensitivity and specificity to distinguish re-intubation was 73 and 87%, respectively. When it was measured by a ventilator, the cutoff value, sensitivity, and specificity were 56 L/min, 73%, and 85%, respectively. CONCLUSIONS: CPF measurement by a ventilator was convenient, affordable, and safe. It had a predictive accuracy for re-intubation similar to that of a spirometer.

Air Stacking: A Detailed Look Into Physiological Acute Effects on Cough Peak Flow and Chest Wall Volumes of Healthy Subjects.

BACKGROUND: Air stacking (AS) is a lung insufflation method that requires the use of a manual insufflator to provide air volumes higher than inspiratory capacity. Neuromuscular patients benefit the most from the maneuver; however, the acute effects of AS in healthy subjects are still unclear. METHODS: Twenty healthy subjects (8 males) were studied by optoelectronic plethysmography to investigate the immediate effects of AS on cough peak flow, operational volume variations, distribution of these volumes in the chest wall compartments (pulmonary rib cage, abdominal rib cage, and abdominal), breathing pattern, and shortening velocity of the respiratory muscles during a protocol that included vital capacity maneuvers and spontaneous coughs before and after AS. RESULTS: Statistically significant increases in cough peak flow (P < .03) and inspiratory capacity (P < .001) were found immediately after AS. During its application, the pulmonary rib cage compartment was the largest contributor (P = .002) to chest wall volume displacement. A significant increase in chest wall tidal volume (P < .001), mainly in the pulmonary rib cage (P < .001), was observed. Significant increases (P < .001) in end-inspiratory chest wall volume were observed with main distribution in pulmonary (P < .001) and abdominal rib cage (P = .01). Significant increases in shortening velocity index of inspiratory muscles (P < .001), expiratory muscles (P < .001), and diaphragm (P < .001) were also observed. In addition, significant decreases in expiratory time (P < .001) and increases in duty cycle (P = .02), breathing frequency (P = .02), minute ventilation (P < .001), maximum inspiratory (P < .001), and expiratory flow (P < .001) were observed. CONCLUSIONS: In healthy subjects, cough peak flow and chest wall volumes can be increased immediately after the application of the AS maneuver.