Peak Expiratory Airflow Research Articles

Comparison of Mechanical Insufflation-Exsufflation and Hypertonic Saline and Hyaluronic Acid With Conventional Open Catheter Suctioning in Intubated Patients.

Open respiratory secretion suctioning with a catheter causes pain and tracheobronchial mucosal injury in intubated patients. The goal of mechanical insufflation-exsufflation (MI-E) is to move secretions proximally and noninvasively by generating a high peak expiratory air flow. Nebulized hypertonic saline with hyaluronic acid (HS-HA) may facilitate suctioning by hydration. We assessed the safety and tolerance of a single session of airway clearance with MI-E and HS-HA in critically ill intubated patients. Adults with a cuffed artificial airway were randomized to (1) open suctioning, (2) open suctioning after HS-HA, (3) MI-E, or (4) MI-E with HS-HA. Adverse events, pain and sedation/agitation scores, and respiratory and hemodynamic variables were collected before, during, and 5-min and 60-min post intervention. One-hundred twenty subjects were enrolled and completed the study. Median (interquartile range [IQR]) Acute Physiology and Chronic Health Evaluation II (APACHE II) score was 22 (16-28); median (IQR) age was 69.0 (57.0-75.7) y, and 90 (75%) were male. Baseline respiratory and hemodynamic variables were comparable. Adverse events occurred in 30 subjects (25%), with no between-group differences. Behavioral pain equivalents and Richmond Agitation-Sedation Scale were higher during suctioning in groups 1 (P < .001) and 2 (P < .001). Independent predictive variables for higher pain and agitation/sedation scores were study groups 1 and 2 and simultaneous analgosedation, respectively. Noradrenaline infusion rates were lower at 60 min in groups 2 and 4. PaO2 /FIO2 had decreased at 5 min after open suctioning in group 1 and increased at 60 min in group 3. We observed no difference in adverse events. MI-E avoids pain and agitation.

Comparison of ventilatory and oxygen consumption measurements of yearling Thoroughbred colts and fillies exercising unridden on an all-weather track

Sex effects on ventilatory and oxygen consumption (V̇O2) measurements during exercise have been identified in humans. This study’s aim was to evaluate the hypothesis that there are sex effects on ventilatory and V̇O2 measurements in exercising, untrained yearling Thoroughbreds (Tb). Forty-one Tbs (16 colts, 25 fillies; 19.8 ± 1.4 months old) were recruited. Physiological, ventilatory and exercise data were gathered from horses exercising unridden at high intensity on an all-weather track from a global positioning-heart rate unit and a portable ergospirometry system. Data were analysed with an unpaired Student’s t-test and the Benjamini-Hochberg correction for multiple testing (P ≤ 0.05 significant). Mean bodyweight (BW, P = 0.002) and wither height (P = 0.04) were greater for colts than fillies. There were no differences in physiological and exercise data and absolute peak V̇O2 between groups. However, fillies had a higher mass specific peak V̇O2 (P = 0.03) than colts (121.5 ± 21.6 mL/kg.min vs. 111.9 ± 27.4 mL/kg.min). The peak breathing frequency was greater for fillies (P < 0.001) while the peak inspiratory (P < 0.001) and expiratory air flow (P < 0.001), peak expiratory tidal volume (VTE; P < 0.001) and peak minute ventilation (V̇E; P = 0.01) were greater for colts; there were no differences for peak VTE and V̇E when adjusted for BW. Differences in BW explain the differences in mass specific peak V̇O2 between groups. Given their morphological differences, it is likely that lung volumes and airway diameters are smaller for fillies, resulting in greater resistance and lower air flows and volumes. Further research is required to investigate the ventilatory differences and how they may change with maturation and impact performance.

Effects of verbal tasks with varying difficulty on real-time respiratory airflow during speech generation in healthy young adults.

Respiratory function is linked to sensory, affective, and cognitive processes and it is affected by environmental constraints such as cognitive demands. It is suggested that specific cognitive processes, such as working memory or executive functioning, may impact breathing. In turn, various lines of research have suggested a link between peak expiratory airflow (PEF) and cognitive function. However, there is scarce experimental support to the above assertions, especially regarding spoken language. Therefore, the present investigation aims to evaluate whether breathing varies as a function of performing verbal naming tasks with different difficulty levels. Thirty healthy young adults, (age M = 25.37 years), participated in the study. Participants were required to perform aloud five verbal tasks ranged in order of difficulty: Reading single words, reading a text passage, object naming, semantic and phonemic fluency. A pneumotachograph mask was employed to acquire simultaneously the verbal responses, and three airflow parameters: Duration, peak, and volume at both stages of the respiratory cycle (i.e., inspiration/expiration). Data were analyzed with one-way repeated measures MANOVA. No significant differences were found between reading single words and object naming. In comparison, distinctive airflow requirements were found for reading a text passage, which were proportionally related to number of pronounced words. Though, the main finding of the study concerns the data on verbal fluency tasks, which not only entailed higher inhaled airflow resources but also a significant PEF. Our data demonstrated that the most difficult tasks, namely semantic and phonemic verbal fluencies, relying on semantic search, executive function, and fast lexical retrieval of words were those requiring important amount of inhaled airflow and displaying a high peak expiratory airflow. The present findings demonstrated for the first time a direct association between complex verbal tasks and PEF. Inconclusive data related to object naming and reading single words are discussed in light of the methodological challenges inherent to the assessment of speech breathing and cognition in this line of investigation.

Aerodynamic Performance and Neuromuscular Control in Patients with Unilateral Vocal Fold Paralysis.

Unilateral vocal fold paralysis (UVFP) causes glottal incompetence and poor vocal efficiency. The influence of laryngeal neuromuscular control on aerodynamics in UVFP remains unclear. This study investigated the relationship between laryngeal muscle activities using quantitative laryngeal electromyography (LEMG) and aerodynamics in UVFP. This prospective study recruited patients with UVFP, and the diagnosis was confirmed with videolaryngostroboscopy and LEMG. The patient received aerodynamic assessment and LEMG of the thyroarytenoid-lateral cricoarytenoid (TA-LCA) muscle complex and the cricothyroid (CT) muscle. The relationship between quantitative LEMG and aerodynamic parameters was analyzed. A total of 134 UVFP patients without concurrent CT muscle involvement were enrolled. Compared with the normal side, the peak turn frequency of the lesioned side was lower in the TA-LCA (p &lt; 0.001) and CT (p = 0.048) muscles. Stepwise linear regression revealed that the turn ratio of TA-LCA muscles was a robust factor in the decrease in peak expiratory airflow (β = -0.34, p = 0.036), mean airflow during voicing (β = -0.28, p = 0.014), and aerodynamic power (β = -0.42, p = 0.019), and an increase in aerodynamic efficiency (β = 27.91, p = 0.012). In addition, the turn ratio of CT muscles was a potent factor in inducing an increase in aerodynamic resistance (β = 14.93, p = 0.029). UVFP without CT involvement still showed suppression of CT muscles on the lesioned side, suggesting that neurological impairment of the TA-LCA complex could cause asymmetrical compensation of CT muscles, further impeding aerodynamics. The residual function of TA-LCA muscle complexes facilitates less air leakage and power dissipation, enhancing aerodynamic efficiency. On the other hand, the symmetrical compensation of the CT muscles improves aerodynamic resistance.

Comparison of Aerodynamic Characteristics During Reading Paragraph Tasks in Normal Male and Female Adults

Purpose: The present study was performed to compare the aerodynamic characteristics of males and females during reading paragraph task.Methods: Thirty-seven normal adult males (18-30 yrs) and thirty-nine normal adult females (18-34 yrs) were participated in this experiment. They read a part of ‘Gaeul’ paragraph with comfortable phonation, and the reading samples were recorded and analyzed by ‘Running Speech’ program of Phonatory Aerodynamic System (PAS).Results: Phonation time (with voicing) and expiratory airflow duration were significantly longer in females, but measures of inspiratory airflow duration, peak expiratory airflow, expiratory and inspiratory volumes were significantly higher in males. The difference in total duration and peak inspiratory airflow did not show statistical significance.Conclusion: Results revealed that there was a significant gender difference in aerodynamic measures of duration and airflow during the reading paragraph task. In evaluating and intervening aerodynamics of voice and voice disorder patients, we should also consider the gender-different aerodynamic characteristics in continuous speech.

Comparison of Aerodynamic Characteristics in Female Adults with Normal Function and with Functional Voice Disorders during Reading Paragraph Tasks

Purpose Aerodynamic characteristics of the patients with voice disorder should be evaluated not only in sustained vowel phonation but also in continuous speech production. This study was performed to compare aerodynamic characteristics during reading paragraph tasks in normal female adults and female adult patients with functional voice disorders. Methods Fifty female adults with normal function and 50 female voice disorder patients participated in aerodynamic measurements during the reading paragraph. Among the results, 9 measurements were analyzed: total duration, number of inspiration, phonation time with voiced sounds, expiratory and inspiratory airflow duration, peak expiratory and inspiratory airflow, expiratory and inspiratory volume. Results In all of the measurements, the patient group showed higher levels than the normal group. Seven measurements, excluding phonation time with voiced sounds and peak inspiratory airflow, showed significant differences between the two groups. Matching the total duration multiple regression analyses showed that 94.2% of the variance in the inspiratory volume was accounted by expiratory volume and number of inspiration, and 56.3% of peak expiratory airflow was done by peak inspiratory airflow. Conclusion It was shown that the patient group used longer duration and higher airflow rate and volume in continuous speech compared to the normal group. We expect that aerodynamic evaluation and analysis in the continuous speech will help the valid assessment and intervention for the patients with voice disorders. Key Words: Aerodynamic evaluation, Continuous speech, Reading paragraph tasks, Voice disorder patient 중심 단어: 공기역학 평가, 연속발화, 문단 ë‚­ë , ìŒì„±ìž¥ì• í™˜ìž

Effect of Menstrual Cycle on Aerodynamic Measures among Singers and Nonsingers

Singer’s vocal apparatus is comprised of her entire body and mind and is easily influenced by hormonal variations. The hormonal changes may have adverse effects on a singer’s vocal performance. There is very little understanding about the aerodynamic measures among singers especially during the different phases of menstrual cycle in Indian population. Aims and objectives: To study the effect of menstrual cycle on aerodynamic measures among singers and nonsingers. The objectives of the study were to profile aerodynamic measures in singers and nonsingers, to compare the aerodynamic measures between the singers and nonsingers, and to study the effect of menstrual phase on aerodynamic measures between singers and nonsingers. Materials and methods: The participants in group I comprised of 30 nonsingers in the age range of 18–25 years. Group II comprised of 15 trained singers (received training formally more than 3 years), and group III had 15 untrained singers in the age range of 18–25 years. The forced vital capacity (FVC), forced expiratory volume in first second (FEVl), and peak expiratory airflow (PEF) were recorded. Descriptive statistics and repeated measure of ANOVA were done to study the effect of menstrual cycle on aerodynamic measures among singers and nonsingers using SPSS 16.0. Results: In the present study, the overall mean scores obtained for all the aerodynamic measures were reduced during menstrual phase as compared to the aerodynamic measures obtained during the follicular phase among both singers and nonsingers.

Premature birth affects the degree of airway dysanapsis and mechanical ventilatory constraints

What is the central question of this study? Adult survivors of preterm birth without (PRE) and with bronchopulmonary dysplasia (BPD) have airflow obstruction at rest and significant mechanical ventilatory constraints during exercise compared with those born at full term (CON). Do PRE/BPD have smaller airways, indexed via the dysanapsis ratio, than CON? What is the main finding and its importance? The dysanapsis ratio was significantly smaller in BPD and PRE compared with CON, with BPD having the smallest dysanapsis ratio. These data suggest that airflow obstruction in PRE and BPD might be because of smaller airways than CON. Adult survivors of very preterm birth (≤32weeks gestational age) without (PRE) and with bronchopulmonary dysplasia (BPD) have obstructive lung disease as evidenced by reduced expiratory airflow at rest and have significant mechanical ventilatory constraints during exercise. Airflow obstruction, in any conditions, could be attributable to several factors, including small airways. PRE and/or BPD could have smaller airways than their counterparts born at full term (CON) owing to a greater degree of dysanaptic airway development during the pre- and/or postnatal period. Thus, the purpose of the present study was to compare the dysanapsis ratio (DR), as an index of airway size, between PRE, BPD and CON. To do so, we calculated DR in PRE (n=21), BPD (n=14) and CON (n=34) individuals and examined flow-volume loops at rest and during submaximal exercise. The DR, using multiple estimates of static recoil pressure, was significantly smaller in PRE and BPD (0.16±0.05 and 0.10±0.03a.u.) compared with CON (0.22±0.04a.u.; both P<0.001) and smallest in BPD (P<0.001). The DR was significantly correlated with peak expiratory airflow at rest (r=0.42; P<0.001) and the extent of expiratory flow limitation during exercise (r=0.60; P<0.001). Our findings suggest that PRE/BPD might have anatomically smaller airways than CON, which might help to explain their lower expiratory airflow rate at rest and during exercise and further our understanding of the consequences of preterm birth and neonatal O2 therapy.

Loss of CDKL5 disrupts respiratory function in mice

Cyclin-dependent kinase-like 5 (CDKL5) is an X-linked gene encoding a serine-threonine kinase that is highly expressed in the central nervous system. Mutations in CDKL5 cause neurological and psychiatric symptoms, including early-onset seizures, motor dysfunction, autistic features and sleep breathing abnormalities in patients. It remains to be addressed whether loss of CDKL5 causes respiratory dysfunction in mice. Here, we examined the respiratory pattern of male Cdkl5−/y mice at 1–3 months of age during resting breathing and respiratory challenge (i.e., hypoxia and hypercapnia) via whole body plethysmography. The results demonstrated that the resting respiratory frequency and tidal volume of Cdkl5−/y mice was unaltered compared to that of WT mice at 1 month of age. However, these mutant mice exhibit transient reduction in tidal volume during respiratory challenge even the reduction was restored at 2 months of age. Notably, the sigh-breathing pattern was changed in Cdkl5−/y mice, showing a transient reduction in sigh volume at 1–2 month of age and long-term attenuation of peak expiratory airflow from 1 to 3 month of age. Therefore, loss of CDKL5 causes breathing deficiency, supporting a CDKL5-mediated regulation of respiratory function in mice.

Measurement of the Maximum Frequency of Electroglottographic Fluctuations in the Expiration Phase of Volitional Cough as a Functional Test for Cough Efficiency

The hypotheses of the present study were that the maximum frequency of fluctuation of electroglottographic (EGG) signals in the expiration phase of volitional cough (VC) reflects the cough efficiency and that this EGG parameter is affected by impaired laryngeal closure, expiratory effort strength, and gender. For 20 normal healthy adults and 20 patients diagnosed with unilateral vocal fold paralysis (UVFP), each participant was fitted with EGG electrodes on the neck, had a transnasal laryngo-fiberscope inserted, and was asked to perform weak/strong VC tasks while EGG signals and a high-speed digital image of the larynx were recorded. The maximum frequency was calculated in the EGG fluctuation region coinciding with vigorous vocal fold vibration in the laryngeal HSDIs. In addition, each participant underwent spirometry for measurement of three aerodynamic parameters, including peak expiratory air flow (PEAF), during weak/strong VC tasks. Significant differences were found for both maximum EGG frequency and PEAF between the healthy and UVFP groups and between the weak and strong VC tasks. Among the three cough aerodynamic parameters, PEAF showed the highest positive correlation with the maximum EGG frequency. The correlation coefficients between the maximum EGG frequency and PEAF recorded simultaneously were 0.574 for the whole group, and 0.782/0.717/0.823/0.688 for the male/female/male-healthy/male-UVFP subgroups, respectively. Consequently, the maximum EGG frequency measured in the expiration phase of VC was shown to reflect the velocity of expiratory airflow to some extent and was suggested to be affected by vocal fold physical properties, glottal closure condition, and the expiratory function.

Voluntary upregulation of reflex cough is possible in healthy older adults and Parkinson's disease.

Cough is an airway-protective mechanism that serves to detect and forcefully eject aspirate material. Existing research has identified the ability of healthy young adults to suppress or modify cough motor output based on external cueing. However, no study has evaluated the ability of people with Parkinson's disease (PD) and healthy older adults (HOAs) to upregulate cough motor output. The goal of this study was to evaluate the ability of people with PD and healthy age-matched controls (HOAs) to upregulate reflex and voluntary cough function volitionally with verbal instruction and visual biofeedback of airflow targets. Sixteen participants with PD and twenty-eight HOAs (56-83 yr old) were recruited for this study. Experimental procedures used spirometry to evaluate 1) baseline reflex cough (evoked with capsaicin) and voluntary sequential cough and 2) reflex and voluntary cough with upregulation biofeedback. Cough airflow was recorded and repeated-measures ANOVA was used to analyze differences in cough airflow parameters. Cough peak expiratory airflow rate and cough expired volume were significantly greater in the cueing condition for both induced reflex (P < 0.001) and voluntary cough (P < 0.001) compared with baseline measures. This is the first study to demonstrate the ability of people with PD and HOAs to upregulate induced reflex and voluntary cough motor output volitionally. These results support the development of studies targeting improved cough effectiveness in patients with airway-protective deficits.NEW & NOTEWORTHY Aspiration pneumonia is a leading cause of death in Parkinson's disease (PD) and results from concurrent dysphagia and dystussia (cough dysfunction). This is the first study to demonstrate that people with PD and healthy age-matched controls can volitionally upregulate induced reflex and voluntary cough effectiveness when presented with novel cueing strategies. Thus targeting upregulation of cough effectiveness via biofeedback may be a viable way to enhance airway protection in people with PD.

Effects of sedation and salbutamol administration on hyperpnoea and tidal breathing spirometry in healthy horses

Sedation is often required to perform pulmonary function testing (PFT) in horses, but drug effects may influence respiratory function. The current study was designed to characterise the effects of sedation and bronchodilator administration on absolute and relative indices of pulmonary function during eupnoeic respiration and carbon dioxide-induced hyperpnoea (rebreathing) in healthy horses using a pneumotachographic spirometry system. Sedation with acetylpromazine (ACP), xylazine, or both drugs in combination was associated with significant reductions in respiratory frequency, minute ventilation and peak airflows during eupnoeic respiration. Peak expiratory airflow occurred later in the respiratory cycle than was observed in untreated horses, and expiratory relative flow-time indices were also affected during eupnoeic respiration. Rebreathing attenuated the effects of sedation on indices of pulmonary function, suggesting that future studies should consider the use of induced hyperpnoea as part of the spirometry protocol. Based on the finding that all sedative agents had some effect on eupnoeic respiration, albeit least pronounced with ACP, the latter drug should be considered for sedation of horses undergoing PFT. Salbutamol increased peak inspiratory flow during eupnoeic respiration in healthy horses.

Measurement of Voluntary Cough Production and Airway Protection in Parkinson Disease

ObjectiveTo examine relations between peak expiratory (cough) airflow rate and swallowing symptom severity in participants with Parkinson disease (PD). DesignCross-sectional study. SettingOutpatient radiology clinic at an acute care hospital. ParticipantsMen and women with PD (N=68). InterventionsParticipants were cued to cough into an analog peak flow meter then swallowed three 20-mL thin liquid barium boluses. Analyses were directed at detecting potential relations among disease severity, swallowing symptom severity, and peak expiratory (cough) airflow rate. Main Outcome MeasuresPeak expiratory (cough) airflow rate and swallow symptom severity. ResultsPeak expiratory (cough) airflow rate varied significantly across swallowing severity classifications. Participants with more severe disease displayed a significant, linear decrease in peak expiratory (cough) airflow rate than those participants with earlier stage, less severe disease. Swallowing symptom severity varied significantly across groups when comparing participants with less severe PD with those with more severe PD. Participants with early stage PD demonstrated little to no swallowing symptoms and had the highest measures of peak expiratory (cough) airflow rate. In contrast, participants with the most severe swallowing symptoms also displayed the lowest measures of peak expiratory (cough) airflow rate. ConclusionsRelations existed among PD severity, swallowing symptom severity, and peak expiratory (cough) airflow rate in participants with PD. Peak expiratory (cough) airflow rate may eventually stand as a noninvasive predictor of aspiration risk in those with PD, particularly those with later stage disease. Inclusion of peak expiratory (cough) airflow rates into existing clinical swallowing assessments may increase the sensitivity and predictive validity of these assessments.

An aerodynamic study on articulation of Mandarin initials

This paper presents findings on the aerodynamic features of Mandarin initial consonants on different articulatory places and manners. Signals of speech, airflow, and air-pressure from 20 speakers (10 males and 10 females) were collected by using Phonatory Aerodynamic System (PAS6600). Parameters, including duration, sound pressure, air-pressure peak, airflow peak, airflow volume were measured. The results showed that: 1) The aerodynamic features of initials vary among different speakers, which might be attributed to their gender or articulation habits. Male speakers have higher air-pressure, airflow peak and expiratory volume (EV) than females, which might be attributed to a greater lung capacity of the male. 2) Aspirated consonants have higher sound pressure level (SPL), expiratory airflow duration (EAD), peak air-pressure (PAP), peak expiratory airflow (PEA) and EV than their unaspirated counterparts. Therefore all these parameters can be regarded as criteria for distinguishing aspirated and unaspirated consonants. 3) The vibration of vocal cords in voiced consonants has an immediate impact on SPL, which leads to higher SPL values than those in voiceless consonants, but air-pressure is just the opposite. The PEA and EV of voiced consonants are close to those of voiceless stops, but these two parameters are far smaller than those for other consonants. 4) The aerodynamics of consonants with different articulatory manners are significantly different, thus the EAD, PAP, PEA and EV parameters can all be regarded as the distinctive features of consonants.

Pediatric Normative Data for the KayPENTAX Phonatory Aerodynamic System Model 6600

The objectives of this study were to (1) establish a preliminary pediatric normative database for the KayPENTAX Phonatory Aerodynamic System (PAS) Model 6600 (KayPENTAX Corp, Montvale, NJ) and (2) identify whether the data obtained were age- and/or gender-dependent. Prospective data collection across groups. A sample of 60 children (30 females and 30 males) with normal voices was divided into three age groups (6.0-9.11, 10.0-13.11, 14.0-17.11 years) with equal distribution of males and females within each group. Five PAS protocols (vital capacity, maximum sustained phonation, comfortable sustained phonation, variation in sound pressure level, voicing efficiency) were used to collect 45 phonatory aerodynamic measures. Measurements for the 45 PAS parameters examined revealed 13 parameters to have a difference that was statistically significant by age and/or gender. There was a significant age×gender interaction for mean pitch in the four protocols that reported this measure. Males in the oldest group had significantly lower mean pitch values than the middle and young groups. Statistically significant main effect differences were noted for seven parameters across three age groups (expiratory volume, expiratory airflow duration, phonation time, pitch range (in 2 protocols), aerodynamic resistance, acoustic ohms). Significant main effect differences for genders (males>females) were found for expiratory volume and peak expiratory airflow. The age- and gender-related differences found for some parameters within each of the five protocols are important for the interpretation of data obtained from PAS. These results could be explained by developmental changes that occur in the male and female respiratory and laryngeal systems.

Performance when Breathing Through Different Respirator Inhalation and Exhalation Resistances During Hard Work

Respirator inspiratory and expiratory breathing resistances impact ventilation and performance when studied independently. However, it is less clear as to how various combinations of inhalation and exhalation resistance affect user performance. The present study investigated the performance of 11 individuals during constant load, demanding work to exhaustion while wearing respirators with eight different combinations of inhalation and exhalation resistance. Exercise performance time, performance rating, minute volume, and peak inspiratory and expiratory airflow were recorded at the end of each test trial, and independent correlations with inhalation resistance and exhalation resistance were assessed. The combined impacts of respirator inhalation and exhalation resistances were quantified as the total external work of breathing (WOB tot ) and correlations between the test variables and WOB tot were also examined. Significantly linear decreases in performance were found with increased inhalation resistances independent of exhalation resistance (R2 = 0.99; p < 0.001) and with increased WOB tot (R2 = 0.92; p < 0.001). Performance also decreased with increased exhalation resistance but no significant relationships were found. Minute volume decreased linearly with increased inhalation resistance independent of exhalation resistance (R2 = 0.99; p < 0.001), but the linear decrease observed between minute volume and WOB tot was weak (R2 = 0.36; p < 0.05). These findings suggest that WOB tot serves as a reliable estimate of the combined impacts of respirator inhalation and exhalation resistances on user performance during hard work, but that inhalation resistance alone serves as a better predictor of ventilation during respirator wear.

Do Oral Mouthguards Affect Ventilation?

Athletes participating in contact sports wear mouthguards (MG) to decrease the risk of concussions and orofacial injuries. However, many athletes resist wearing mouthguards citing reasons that include discomfort, problems with speech and breathing during play. Breathing difficulties may suggest some limitations with ventilation. PURPOSE To examine peak inspiratory and peak expiratory air flow at specific ventilatory rates using different types of MG and a no MG condition. METHODS Seven MG (3 stock, 3 boil and bite, and 1 custom-fitted; 5 unimolar and 2 bimolar) and a no MG condition were compared. MG were fitted into an oral dental model and air was ventilated through the model at three flow rates (30, 45, 60 strokes·min−1) using 2 and 3 liter syringes. Inspiratory and expiratory flows were recorded using a Medisoft Ergocard. Peak flow (L·s−1), FEF25, FEF50, FEF75, FIF25, FIF50 and FIF75 were recorded for 10 strokes at each ventilation rate. Data were analyzed using a 3-way (8 MG; 6 flow rates; 2 flow directions Insp/Exp) repeated measures ANOVA for the dependant variable, peak flow. RESULTS There was a significant main effect for MG (F = 11.97; p < 0.001) with lower peak air flow for the two bimolar MG compared to the no MG condition. There were significant interaction effects between MG and flow rates. At the lowest ventilation (60 L·min−1), peak flow was similar to the no MG condition for 5 of the 7 MG. At the highest ventilation (180 L·min−1), peak flow was significantly higher with no MG compared to 4 of the 7 MG conditions, including both bimolar MG. CONCLUSIONS These findings suggest that mouthguards do not impair ventilation at low flow rates, however peak flow is lowered at high ventilation with bimolar mouthguards and some unimolar mouthguards.

Physiological and psychological reactivity in women with asthma: the effects of anxiety and menstrual cycle phase

The relation between menstrual cycle timing, panic attacks, and diagnosis of asthma was explored in this study. Women with or without asthma and with or without a history of panic attacks engaged in a psychophysiological task during either the intermenstrual or premenstrual cycle phase and completed self-report measures of menstrual symptoms and attitudes, general psychological symptoms, and attitudes toward illness. No significant differences were identified for psychological or psychophysiological measures with menstrual cycle phase as a factor. However, women with both asthma and a history of panic attacks reported more general psychological distress than women in the other groups, and more state anxiety than controls. Women in the asthma, asthma and panic, and panic groups reported higher anxiety sensitivity than the control group. After listening to asthma-related scenes, women with asthma exhibited a decrease in peak expiratory air flow, and women with asthma and panic exhibited increased skin conductance response magnitude. Implications for the role of anxiety in lung function are discussed, as well as directions for future research with asthma and anxiety populations.

Comparison of the performance of linear resistance and ultrasonic pneumotachometers at rest and during lobeline-induced hyperpnoea

The performance of a Fleisch No. 5 pneumotachometer (F), and two commercial ultrasonic pneumotachometers, the BRDL (B) and the Spiroson (S) systems were compared in respect to their use for determination of ventilatory parameters at rest and during lobeline-induced hyperpnoea. Five clinically healthy Thoroughbred horses were tested with the three pneumotachometers in random order. Respiratory airflow, respired gas concentrations, oesophageal pressures, pressures within the mask systems and arterial blood gases were determined before and during lobeline-induced hyperpnoea. Because measured peak expiratory airflow rates exceeded the stated linear range of the Fleisch pneumotachometer (~ ± 25 l s–1) differential pressure-flow curves were determined in vitro over the range of flows recorded in vivo. Expired flows greater than the linear range were corrected according to the derived regression equation. No differences in any of the measured variables among the three systems were present at rest. At peak ventilation of lobeline-induced hyperpnoea mask pressures [Δ Pmask(mean (SEM)): F: 9·6 (2·8) cm H2O, B: 0·8 (0·4) cm H2O, S: 1·4 (0·8) cm H2O] and end tidal carbon dioxide [ET CO2(mean (SEM)): F: 2·6 (0·1)%, B: 2·1 (0·2)%, S: 2·1 (0·1)%] were significantly higher in system F. Despite a tendency for respiratory frequency and peak inspired and expired flows, to be lower with system F, no significant differences in the measurements of ventilatory mechanics were detected. In conclusion, the ultrasonic flowmeters pose significantly lower resistive loads onto the respiratory system during ventilation above resting levels than Fleisch No 5 pneumotachometers. However, at the flowrates achieved during lobeline-induced hyperpnoea an in vitro calibration of the differential pressure–flow relationship allows correction for expiratory alinearity in system F. In addition, the performance of the Spiroson flowmeter is accurate in determining ventilatory mechanics at rest and during lobeline-induced hyperpnoea.

CHARACTERIZATION OF RESPIRATORY EXPOSURE TO AND EFFECTS OF COLD-AIR HYPERVENTILATION IN GUINEA PIGS

The purpose of this study was to characterize the respiratory effects of single and repeated controlled exposures to clean warm humid and cold dry air in a new model of anesthetized, mechanically ventilated guinea pigs, and to compare findings with known effects in humans. Intratracheal air (Ttr) and retrotracheal tissue (Toe) temperatures and peak expiratory airflow (PEF), tidal volume (VT), heart rate, and blood pressure of hyperventilating animals were measured continuously. Four consecutive 10-min exposures to warm humid air (n = 7) produced slight airway warming and minimal lung function changes during the exposure. In a single 10-min exposure to cold dry air (n = 39), Ttr