Pandemic printing: a novel 3D-printed swab for detecting SARS-CoV-2.

OBJECTIVES: To design and evaluate 3D-printed nasal swabs for collection of samples for SARS-CoV-2 testing. DESIGN: An iterative design process was employed. Laboratory evaluation included in vitro assessment of mock nasopharyngeal samples spiked with two different concentrations of gamma-irradiated SARS-CoV-2. A prospective clinical study compared SARS-CoV-2 and human cellular material recovery by 3D-printed swabs and standard nasopharyngeal swabs. SETTING, PARTICIPANTS: Royal Melbourne Hospital, May 2020. Participants in the clinical evaluation were 50 hospital staff members attending a COVID-19 screening clinic and two inpatients with laboratory-confirmed COVID-19. INTERVENTION: In the clinical evaluation, a flocked nasopharyngeal swab sample was collected with the Copan ESwab and a mid-nasal sample from the other nostril was collected with the 3D-printed swab. RESULTS: In the laboratory evaluation, qualitative agreement with regard to SARS-CoV-2 detection in mock samples collected with 3D-printed swabs and two standard swabs was complete. In the clinical evaluation, qualitative agreement with regard to RNase P detection (a surrogate measure of adequate collection of human cellular material) in samples collected from 50 hospital staff members with standard and 3D-printed swabs was complete. Qualitative agreement with regard to SARS-CoV-2 detection in three pairs of 3D-printed mid-nasal and standard swab samples from two inpatients with laboratory-confirmed SARS-CoV-2 was also complete. CONCLUSIONS: Using 3D-printed swabs to collect nasal samples for SARS-CoV-2 testing is feasible, acceptable to patients and health carers, and convenient.

Vibration pattern recognition using a compressed histogram of oriented gradients for snoring source analysis.

BACKGROUND: Snoring source analysis is essential for an appropriate surgical decision for both simple snorers and obstructive sleep apnea/hypopnea syndrome (OSAHS) patients. OBJECTIVE: As snoring sounds carry significant information about tissue vibrations within the upper airway, a new feature entitled compressed histogram of oriented gradients (CHOG) is proposed to recognize vibration patterns of the snoring source acoustically by compressing histogram of oriented gradients (HOG) descriptors via the multilinear principal component analysis (MPCA) algorithm. METHODS: Each vibration pattern corresponds to a sole or combinatorial vibration among the four upper airway soft tissues of soft palate, lateral pharyngeal wall, tongue base, and epiglottis. 1037 snoring events from noncontact sound recordings of 76 simple snorers or OSAHS patients during drug-induced sleep endoscopy (DISE) were evaluated. RESULTS: With a support vector machine (SVM) as the classifier, the proposed CHOG achieved a recognition accuracy of 89.8% for the seven observable vibration patterns of the snoring source categorized in our most recent work. CONCLUSION: The CHOG outperforms other single features widely used for acoustic analysis of sole vibration site.

Current approaches to instrumental assessment of swallowing in children.

PURPOSE OF THE REVIEW: This article reviews recent developments in the instrumental assessment of swallowing in children with a specific focus on research published between January 2017 and June 2018. RECENT FINDINGS: Instrumental swallowing assessments reported in the time period included: videofluoroscopic study of swallowing, digital cervical auscultation, dynamic ultrasound, high-resolution impedance manometry, nasal airflow thermistry and respiratory inductance plethysmography. Several studies were found exploring tools to objectively quantify videofluoroscopic study of swallowing data; swallowing from the mouth through to stomach was addressed including approaches to analysing mastication as well as evaluating oesophageal motility disorders. SUMMARY: Even though a vast range of instrumentation were studied, lack of clarity on clinical feasibility and objective measures that facilitate medical decision-making in practice mean further research is required to provide guidance on implementation. Promising novel approaches to aid the quantification of swallowing physiology from the mouth, pharynx and through to the oesophagus are emerging.

Systematic review of instruments aimed at evaluating the severity of bronchiolitis.

OBJECTIVE: No recent studies have performed a systematic review of all available instruments aimed at evaluating the severity of bronchiolitis. The objective of the present study was to perform a systematic review of instruments aimed at evaluating the severity of bronchiolitis and to evaluate their measurement properties. METHODS: A systematic search of the literature was performed in order to identify studies in which an instrument for evaluating the severity of bronchiolitis was described. Instruments were evaluated based on their reliability, validity, utility, endorsement frequency, restrictions in range, comprehension, and lack of ambiguity. RESULTS: A total of 77 articles, describing a total of 32 different instruments were included in the review. The number of items included in the instruments ranged from 2 to 26. Upon analyzing their content, respiratory rate turned out to be the most frequently used item (in 26/32, 81.3% of the instruments), followed by wheezing (in 25/32, 78.1% of the instruments). In 18 (56.3%) instruments, there was a report of at least one of their measurement properties, mainly reliability and utility. Taking into consideration the information contained in the instruments, as well as their measurement properties, one was considered to be the best one available. CONCLUSIONS: Among the 32 instruments aimed at evaluating the severity of bronchiolitis that were identified and systematically examined, one was considered to be the best one available. However, there is an urgent need to develop better instruments and to validate them in a more comprehensive and proper way.

Diagnostic accuracy of nasal cannula versus microphone for detection of snoring.

OBJECTIVE: Snoring is a common reason for referral to a sleep unit. Although there are several instruments to measure snoring, there is no gold standard for this purpose. In this study, we determine the diagnostic accuracy of the cannula as compared with the microphone, which are the two most commonly used tools. STUDY DESIGN: We performed a cross-sectional study of 75 patients who underwent baseline home sleep apnea testing for any reason. METHODS: Snore intensity and percentage were assessed during Home sleep-apnea testing via nasal cannula and microphone in all patients. We performed a complete diagnostic accuracy analysis, assuming the microphone to be the reference instrument use in order to compare it with the cannula. RESULTS: The intra-class correlation coefficient between the cannula and microphone for the percentage of snoring was 0.25. The Bland Bland-Altman analysis to determine the agreement regarding the percentage of snoring showed a lower limit of -57.73 and an upper limit of 20.30. A linear regression analysis of the differences produced a negative slope of -0.86. The receiver operating characteristic curve for severe snoring using the cannula produced an area under the curve of 0.67 (P = 0.019). The cannula showed a sensitivity of 57.89 and a specificity of 73.21. CONCLUSION: The nasal cannula showed poor reliability and accuracy for measuring snoring. LEVEL OF EVIDENCE: 2b. Laryngoscope, 127:2886-2890, 2017.

Recent advances in the diagnosis and management of obstructive sleep apnea.

Affecting a large number of middle-aged, frequently overweight subjects, obstructive sleep apnea (OSA) is the most common sleep related breathing disorder. Partial or complete upper airway (UA) collapse during sleep causing repeated apneic episodes, which is the leading pathophysiological mechanism underlying the disorder, results in arterial oxygen desaturation and recurrent arousals from sleep to re-establish airway patency. Untreated OSA is commonly associated with a range of adverse consequences, including cardiovascular complications, such as arterial and/or pulmonary hypertension, arrhythmias, stroke, as well as diabetes mellitus and metabolic syndrome, and motor vehicle accidents. Evidence-based guidelines are presently available for the diagnosis and management of OSA, and a variety of updated testing and treatment procedures and devices including some that are able to identify the site and degree of airway obstruction are becoming increasingly available. As the "one size fits all" approach falls to the wayside, a tailored personal therapeutic strategy is becoming increasingly popular in the field of sleep medicine. The aim of this review is to provide an overview for practicing clinicians on recent advances in the evaluation and management of obstructive sleep apnea in adults.

Real-time 3D visualization of the thoraco-abdominal surface during breathing with body movement and deformation extraction.

Real-time 3D visualization of the breathing displacements can be a useful diagnostic tool in order to immediately observe the most active regions on the thoraco-abdominal surface. The developed method is capable of separating non-relevant torso movement and deformations from the deformations that are solely related to breathing. This makes it possible to visualize only the breathing displacements. The system is based on the structured laser triangulation principle, with simultaneous spatial and color data acquisition of the thoraco-abdominal region. Based on the tracking of the attached passive markers, the torso movement and deformation is compensated using rigid and non-rigid transformation models on the three-dimensional (3D) data. The total time of 3D data processing together with visualization equals 20 ms per cycle.In vitro verification of the rigid movement extraction was performed using the iterative closest point algorithm as a reference. Furthermore, a volumetric evaluation on a live subject was performed to establish the accuracy of the rigid and non-rigid model. The root mean square deviation between the measured and the reference volumes shows an error of ±0.08 dm(3) for rigid movement extraction. Similarly, the error was calculated to be ±0.02 dm(3) for torsional deformation extraction and ±0.11 dm(3) for lateral bending deformation extraction. The results confirm that during the torso movement and deformation, the proposed method is sufficiently accurate to visualize only the displacements related to breathing. The method can be used, for example, during the breathing exercise on an indoor bicycle or a treadmill.

Validation of polyvinylidene fluoride nasal sensor to assess nasal obstruction in comparison with subjective technique.

OBJECTIVE: The aim of this study is to validate the applicability of the PolyVinyliDene Fluoride (PVDF) nasal sensor to assess the nasal airflow, in healthy subjects and patients with nasal obstruction and to correlate the results with the score of Visual Analogue Scale (VAS). METHODS: PVDF nasal sensor and VAS measurements were carried out in 50 subjects (25-healthy subjects and 25 patients). The VAS score of nasal obstruction and peak-to-peak amplitude (Vp-p) of nasal cycle measured by PVDF nasal sensors were analyzed for right nostril (RN) and left nostril (LN) in both the groups. Spearman's rho correlation was calculated. The relationship between PVDF nasal sensor measurements and severity of nasal obstruction (VAS score) were assessed by ANOVA. RESULTS: In healthy group, the measurement of nasal airflow by PVDF nasal sensor for RN and LN were found to be 51.14±5.87% and 48.85±5.87%, respectively. In patient group, PVDF nasal sensor indicated lesser nasal airflow in the blocked nostrils (RN: 23.33±10.54% and LN: 32.24±11.54%). Moderate correlation was observed in healthy group (r=-0.710, p<0.001 for RN and r=-0.651, p<0.001 for LN), and moderate to strong correlation in patient group (r=-0.751, p<0.01 for RN and r=-0.885, p<0.0001 for LN). CONCLUSION: PVDF nasal sensor method is a newly developed technique for measuring the nasal airflow. Moderate to strong correlation was observed between PVDF nasal sensor data and VAS scores for nasal obstruction. In our present study, PVDF nasal sensor technique successfully differentiated between healthy subjects and patients with nasal obstruction. Additionally, it can also assess severity of nasal obstruction in comparison with VAS. Thus, we propose that the PVDF nasal sensor technique could be used as a new diagnostic method to evaluate nasal obstruction in routine clinical practice.

Improved repeatability of nasal potential difference with a larger surface catheter.

OBJECTIVE: To increase the power of nasal potential difference (NPD) as a biomarker of CFTR function, improvement of its repeatability is needed. We evaluated the improvement in repeatability resulting from measuring NPD (1) over a larger surface area and (2) at a fixed location. METHODS: To assess repeatability, NPD was measured on two occasions with a new method using a larger surface catheter at fixed locations on the nasal floor (LSC-floor(5cm) and LSC-floor(3cm)) or at the most negative basal potential (LSC-floor(max)); with a sidehole catheter on the nasal floor at 5 cm) from the nasal margin (SHC-floor(5cm)) or at the most negative potential (SHC-floor(max)); and with an endhole catheter below the inferior surface of the lower turbinate at the most negative potential (EHC-turb(max)). RESULTS: The within-subject standard deviation (S(w)) for repeated measurements of the total chloride response in the controls was smallest with the LSC-floor at a fixed location (LSC-floor(5cm) 3.1 mV; 95% CI 2.3-4.6 mV) and highest with the SHC-floor (SHC-floor(max) 14.6 mV; 95% CI 10.9-22.2 mV) or the EHC-turbinate (EHC-turb(max) 12.5 mV; 95% CI 10.7-23.0 mV) at the most negative basal potential. Measuring with the LSC-floor at the maximal potential increased the Sw (LSC-floor(max) 8.8 mV, 95% CI 6.0-16.1 mV, p=0.009 vs LSC-floor(5cm)), while measuring with the SHC-floor at a fixed location slightly decreased the Sw (SHC-floor(5cm) 9.8 mV, 95% CI 8.9-20.6 mV, p=0.06 vs SHC-floor(max)). In patients with cystic fibrosis, the S(w) was comparable, between 2.2 mV and 4.3 mV. Sample size calculations for trials using NPD to assess changes in ion transport showed that the number of subjects to be included could be approximately halved measuring with the larger surface catheter at a fixed location vs SHC or EHC at fixed locations. CONCLUSION: Measuring the NPD at a fixed location and over a larger surface resulted in increased repeatability and thereby also power as a biomarker of CFTR modulation.

Complementary home mechanical ventilation techniques. SEPAR Year 2014.

This is a review of the different complementary techniques that are useful for optimizing home mechanical ventilation (HMV). Airway clearance is very important in patients with HMV and many patients, particularly those with reduced peak cough flow, require airway clearance (manual or assisted) or assisted cough techniques (manual or mechanical) and suctioning procedures, in addition to ventilation. In the case of invasive HMV, good tracheostomy cannula management is essential for success. HMV patients may have sleep disturbances that must be taken into account. Sleep studies including complete polysomnography or respiratory polygraphy are helpful for identifying patient-ventilator asynchrony. Other techniques, such as bronchoscopy or nutritional support, may be required in patients on HMV, particularly if percutaneous gastrostomy is required. Information on treatment efficacy can be obtained from HMV monitoring, using methods such as pulse oximetry, capnography or the internal programs of the ventilators themselves. Finally, the importance of the patient's subjective perception is reviewed, as this may potentially affect the success of the HMV.

Evaluation of polyvinylidene fluoride nasal sensor to assess deviated nasal septum in comparision with peak nasal inspiratory flow measurements.

BACKGROUND: Deviated nasal septum (DNS) is one of the major causes of nasal obstruction. Polyvinylidene fluoride (PVDF) nasal sensor is the new technique developed to assess the nasal obstruction caused by DNS. This study evaluates the PVDF nasal sensor measurements in comparison with PEAK nasal inspiratory flow (PNIF) measurements and visual analog scale (VAS) of nasal obstruction. METHODS: Because of piezoelectric property, two PVDF nasal sensors provide output voltage signals corresponding to the right and left nostril when they are subjected to nasal airflow. The peak-to-peak amplitude of the voltage signal corresponding to nasal airflow was analyzed to assess the nasal obstruction. PVDF nasal sensor and PNIF were performed on 30 healthy subjects and 30 DNS patients. Receiver operating characteristic was used to analyze the DNS of these two methods. RESULTS: Measurements of PVDF nasal sensor strongly correlated with findings of PNIF (r = 0.67; p < 0.01) in DNS patients. A significant difference (p < 0.001) was observed between PVDF nasal sensor measurements and PNIF measurements of the DNS and the control group. A cutoff between normal and pathological of 0.51 Vp-p for PVDF nasal sensor and 120 L/min for PNIF was calculated. No significant difference in terms of sensitivity of PVDF nasal sensor and PNIF (89.7% versus 82.6%) and specificity (80.5% versus 78.8%) was calculated. CONCLUSION: The result shows that PVDF measurements closely agree with PNIF findings. Developed PVDF nasal sensor is an objective method that is simple, inexpensive, fast, and portable for determining DNS in clinical practice.

Validation of a portable nitric oxide analyzer for screening in primary ciliary dyskinesias.

BACKGROUND: Nasal nitric oxide (nNO) levels are very low in primary ciliary dyskinesia (PCD) and it is used as a screening test. METHODS: We assessed the reliability and usability of a hand-held analyser in comparison to a stationary nitric oxide (NO) analyser in 50 participants (15 healthy, 13 PCD, 22 other respiratory diseases; age 6-79 years). Nasal NO was measured using a stationary NO analyser during a breath-holding maneuver, and using a hand-held analyser during tidal breathing, sampling at 2 ml/sec or 5 ml/sec. The three methods were compared for their specificity and sensitivity as a screen for PCD, their success rate in different age groups, within subject repeatability and acceptability. Correlation between methods was assessed. RESULTS: Valid nNO measurements were obtained in 94% of participants using the stationary analyser, 96% using the hand-held analyser at 5 ml/sec and 76% at 2 ml/sec. The hand-held device at 5 ml/sec had excellent sensitivity and specificity as a screening test for PCD during tidal breathing (cut-off of 30 nL/min,100% sensitivity, >95% specificity). The cut-off using the stationary analyser during breath-hold was 38 nL/min (100% sensitivity, 95% specificity). The stationary and hand-held analyser (5 ml/sec) showed reasonable within-subject repeatability(% coefficient of variation = 15). CONCLUSION: The hand-held NO analyser provides a promising screening tool for PCD.

Concordance and discriminatory power of cough measurement devices for individuals with Parkinson disease.

BACKGROUND: Dysphagia and aspiration pneumonia are two causes of morbidity in Parkinson disease (PD). In PD, impaired airway clearance can lead to penetration of foreign material, resulting in a high prevalence of aspiration pneumonia and death. This study examines three different devices for measurement of peak airflow during voluntary cough in healthy control subjects and those with PD. Two simple and low-cost devices for measuring peak cough airflow were compared with the "gold standard" pneumotachograph. METHODS: Thirty-five healthy control subjects and 35 individuals with PD produced voluntary cough at three perceived strengths (weak, moderate, and strong cough) for each of the three devices. RESULTS: A significant difference in mean peak cough airflow was demonstrated for disease (F[1,56] = 4.0, P < .05) and sex (F[1,56] = 9.59, P < .003) across devices. The digital and analog meters were comparable to the gold standard demonstrating no significant difference (statistical) by device (digital vs analog) in receiver operating characteristic curve analysis. Both devices were discriminative of the presence of PD. CONCLUSIONS: The analog and digital peak airflow meters are suitable alternatives to the gold standard pneumotachograph due to their low cost, portability, ease of use, and high sensitivity relative to normative peak cough airflows. Voluntary cough airflow measures may serve as a noninvasive means of screening for aspiration risk in target populations. Additionally, quantification of cough strength through use of predetermined limens for weak, moderate, and strong cough may assist clinicians in better describing and tracking cough strength as a contributing factor to aspiration risk.

Abbreviated multi-breath washout for calculation of lung clearance index.

INTRODUCTION: Various functional residual capacity (FRC) repeatability criteria have been proposed for lung clearance index (LCI) measurement by multiple breath washout (MBW). Adult guidelines recommend three technically acceptable tests with FRC values within 10%, whilst preschool guidelines recommend two such tests. Feasibility of and need for recommendations in children is unclear. METHODS: Retrospective analysis of MBW data was undertaken in healthy control (n = 90) and cystic fibrosis (CF) subjects (n = 108) encompassing infancy, pre-school and school age ranges. Feasibility of FRC repeatability recommendations was investigated in those with three technically acceptable tests. Validity of mean LCI from the first two tests alone (vs. all three) was investigated by comparing mean data and sensitivity to detect abnormal peripheral airway function in CF. RESULTS: LCI coefficient of variation (CoV) was related to FRC CoV (P < 0.001) and disease category (P = 0.002). Application of adult repeatability criteria decreased LCI CoV (4.7 vs. 8.5%, P < 0.001), but had poor feasibility beyond infancy (62/150, 41%). Preschool recommendations increased feasibility but only to 70% overall. There was no difference in mean LCI (All three minus 1st two tests) in healthy controls [mean (95% CI) difference: 0.02 (-0.01, 0.06; P = 0.15)], this difference being statistically but not clinically significant in CF subjects [0.07 (0.00,0.13; P = 0.04)]. Sensitivity in CF subjects was unaffected. CONCLUSION: Adult FRC repeatability recommendations improved LCI repeatability in pediatric subjects, but poor feasibility limited utility. In an experienced pediatric MBW center, recent preschool recommendations can be extended to two technically acceptable tests, irrespective of FRC repeatability, without significantly affecting mean LCI or compromising sensitivity.

Performance of frontloading for smear microscopy in the diagnosis of pulmonary tuberculosis: a cross-sectional study at a referral hospital in Uganda.

OBJECTIVE: To compare the performance of frontloading and the standard WHO method for diagnosis of pulmonary TB at Mulago Hospital in order to validate the technique in this setting. METHODS: This was a cross-sectional study in which 229 adult (≥18 years) TB suspects were consecutively enrolled. Suspects submitted three sputum samples as follows: at initial presentation, one hour after the first sample, and the next morning. The first and next morning samples formed the standard WHO method, while the first and the one hour later samples formed the frontloading method. Sample processing was by the standard N-acetyl L-cystein (NALC)-NaOH method, and fluorescent microscopy was done for both methods, while cultures of the first sample on Lowenstein-Jensen slants acted as a gold standard. The sensitivity, specificity and predictive values for the WHO standard and frontloading methods were compared. RESULTS: The sensitivity of both the frontloading and standard schemes was 91.1% while their specificities were 86.2% and 91.7% respectively. There was excellent agreement between the diagnostic capacity of the two methods (kappa statistic = 0.87, P<0.0001). The positive predictive value for the frontloading scheme was 87.2% and that for the standard approach was 91.9%, while the negative predictive values were 90.4% and 90.9%, respectively. Among the HIV positive patients, frontloading identified 59/79 (74.7%) culture positive samples while the standard approach identified 55/79 (69.6%). In the HIV sero-negative category, on the other hand, front-loading identified 48/110 (43.6%) culture positive samples compared to 45/110 (40.9%) by the standard approach. CONCLUSION: Frontloading based on smear examination of two same-day sputum samples has a similar performance to the current standard method and would not be associated with any significant missed diagnosis. It may therefore be advocated for use in our setting so as to reduce time to completion of diagnosis and patient loss to follow-up.

Comparison of maximal inspiratory pressure, tracheal airway occlusion pressure, and its ratio in the prediction of weaning outcome: impact of the use of a digital vacuometer and the unidirectional valve.

OBJECTIVE: To investigate the predictive value of the maximal inspiratory pressure obtained by a digital vacuometer using a unidirectional valve (P(ImaxUV)) as to weaning outcome, and to compare its performance with the respiratory drive using airway occlusion pressure at 0.1 second (P(0.1)), and P(0.1)/P(ImaxUV). METHODS: Patients on mechanical ventilation for > 24 hours who fulfilled the weaning criteria were prospectively enrolled. Measurements of P(ImaxUV) and P(0.1) were accomplished with a digital vacuometer with a unidirectional valve that allows only exhalation. Measured values were electronically recorded and stored on the digital vacuometer measurement device. Cutoff points for the used parameters were: absolute values of P(ImaxUV) > 30 cm H(2)O, P(0.1) < 2.3 cm H(2)O, and P(0.1)/P(ImaxUV) < 0.10. Receiver operating characteristic curves were calculated to compare the predictive values of the indexes. RESULTS: One hundred three subjects completed the test. The areas under the receiver operating characteristic curve were 0.79 ± 0.04, 0.65 ± 0.05, and 0.74 ± 0.04 for P(ImaxUV), P(0.1), and P(0.1)/P(ImaxUV), respectively. The area under the receiver operating characteristic curve for P(ImaxUV) was higher than for P(0.1) and P(0.1)/P(ImaxUV), but statistical significance was only found against P(0.1) (P = .007). CONCLUSIONS: Every studied index had only a modest performance regarding prediction of weaning outcome. Of note, P(ImaxUV) values obtained by digital technology using a unidirectional valve performed better than historically reported using a conventional techniques, surpassing P(0.1) and P(0.1)/P(ImaxUV) in this regard.

Evaluation of the inspiratory pressure using a digital vacuometer in mechanically ventilated patients: analysis of the time to achieve the inspiratory peak.

BACKGROUND: The measurement of the maximal inspiratory pressure (P(Imax)) is of great importance in choosing the time for the start of weaning. OBJECTIVE: To measure the inspiratory pressure in mechanically ventilated patients suitable for weaning to determine the point at which the P(Imax) is achieved within 60 seconds of observation, and analyze factors associated with P(Imax) values. METHODS: Measurement of P(Imax) was accomplished with a digital vacuometer with a unidirectional valve, which allows only exhalation (P(ImaxUV)). With this technique, values are registered and stored, remaining accessible whenever necessary. All patients were on mechanical ventilation, and met the criteria recommended by the American Thoracic Society/European Respiratory Society in 2007 to undergo weaning trial. RESULTS: Eighty-four from the 87 enrolled patients completed the test. No patients reached the P(ImaxUV) in the first 20 seconds of observation. P(ImaxUV) was achieved between 20.1 and 40 seconds in 12 patients (14.0%), and between 40.1 and 60 seconds in 72 cases (86.0%). In a multivariate analysis model in which age, sex, days of mechanical ventilation, APACHE score, and respiratory drive (measured as airway-occlusion pressure 0.1 s after the start of inspiratory flow [P(0.1)]) were included, only age (P = .006) and P(0.1) (P = .003) were significantly associated with the values of P(ImaxUV). CONCLUSIONS: Within an observation period of 60 seconds, the majority of patients reached the maximal inspiratory peak between 40.1 and 60 seconds. Older patients were found to have lower P(ImaxUV) values, whereas higher values for P(0.1) strongly correlated with higher P(ImaxUV) values. These findings are potentially useful to improve successful weaning prediction in the future, but further studies are needed to better clarify this issue.