The 3D-printed miniplate-jig system: a new, rapid, precise, and user-friendly approach to miniplate fixation of free-tissue mandibular reconstructions.

Patient-specific, additively manufactured (printed) titanium reconstruction plates have been widely used to improve accuracy and efficiency of fibular flap reconstruction of the mandible. Miniplates possess some potential advantages over single-piece reconstruction plates, however multiple-miniplate fixation can be more technically demanding and may lengthen the duration of surgery. Furthermore, incremental angulation errors in screw placement for each miniplate could compromise overall dimensional accuracy of the neomandibular reconstruction. This preliminary article reports the first clinical use of a new patient-specific, printed titanium miniplate-jig system in a patient undergoing hemimandibulectomy for osteoradionecrosis of the mandible withfibular flap reconstruction. Our initial experience with the new deviceand technique demonstratesa quick, user friendly, and precise method for the placement and fixation of multiple miniplates in fibular-flap reconstruction of the mandible.

Impaired exercise outcomes with significant bronchodilator responsiveness in children with prematurity-associated obstructive lung disease.

INTRODUCTION: Preterm-born children have their normal in-utero lung development interrupted, thus are at risk of short- and long-term lung disease. Spirometry and exercise capacity impairments have been regularly reported in preterm-born children especially those who developed chronic lung disease of prematurity (CLD) in infancy. However, specific phenotypes may be differentially associated with exercise capacity. We investigated exercise capacity associated with prematurity-associated obstructive (POLD) or prematurity-associated preserved ratio of impaired spirometry (pPRISm) when compared to preterm- and term-controls with normal lung function. MATERIALS AND METHODS: Preterm- and term-born children identified through home screening underwent in-depth lung function and cardiorespiratory exercise testing, including administration of postexercise bronchodilator, as part of the Respiratory Health Outcomes in Neonates (RHiNO) study. RESULTS: From 241 invited children, aged 7-12 years, 202 underwent exercise testing including 18 children with POLD (percent predicted (%)FEV1 and FEV1 /FVC < LLN); 12 pPRISm (%FEV1 < LLN and FEV1 /FVC ≥ LLN), 106 preterm-controls (PTc , %FEV1 ≥ LLN) and 66 term-controls (Tc , %FEV1 > 90%). POLD children had reduced relative workload, peak O2 uptake, CO2 production, and minute ventilation compared to Tc , and used a greater proportion of their breathing reserve compared to both control groups. pPRISm and PTc children also had lower O2 uptake compared to Tc . POLD children had the greatest response to postexercise bronchodilator, improving their %FEV1 by 19.4% (vs 6.3%, 6% 6.3% in pPRISm PTc, Tc , respectively; p < .001). CONCLUSION: Preterm-born children with obstructive airway disease had the greatest impairment in exercise capacity, and significantly greater response to postexercise bronchodilators. These classifications can be used to guide treatment in children with POLD.

Skin biomechanical properties and leg volume in aging healthy adults.

BACKGROUND: In adults ageing is accompanied by changes in limb volume and skin biomechanical properties. OBJECTIVES: To explore the relationship between body size, aging, skin biomechanics, and leg volume, VLeg and to define predictive equations linking leg volume with these properties. METHODS: Sixty-two healthy adults (Age 18-80 years, M:F 45:55) were recruited. Anthropomorphic measures were recorded along with VLeg (via circumferential method) and skin tone, stiffness, and elastance (via tonometry). Regression analysis was performed to define relationship between the measured parameters. RESULTS: In healthy adults bilateral VLeg were the same regardless of leg or sex, 5791 ± 1363 for females and 6151 ± 1203 mls for males. VLeg was positively correlated to body weight, where VLeg (mls) = 1058 + 69 × Wt (kg) for females and VLeg (mls) = 539 + 65 × Wt (Kg) of body weight for males. Skin surface biomechanical properties varied with sex, leg volume, and location on the leg with the malleolus exhibiting the stiffest surface. CONCLUSION: The study shows that anthropometric measures change with sex and leg size are multifactorial and body weight, sex, and skin condition as important determinant factors of leg volume.

Inhaled Corticosteroids Alone and in Combination With Long-Acting ß2 Receptor Agonists to Treat Reduced Lung Function in Preterm-Born Children: A Randomized Clinical Trial.

Importance: Decreases in future lung function are a hallmark of preterm birth, but studies for management of decreased lung function are limited. Objective: To determine whether 12 weeks of treatment with inhaled corticosteroids (ICS) alone or in combination with long-acting ß2 agonists (LABA) improves spirometry and exercise capacity in school-aged preterm-born children who had percent predicted forced expiratory volume in 1 second (%FEV1) less than or equal to 85% compared with inhaled placebo treatment. Design, Setting, and Participants: A double-blind, randomized, placebo-controlled trial was conducted to evaluate ICS and ICS/LABA against placebo. Preterm-born children (age, 7-12 years; gestation ≤34 weeks at birth) who did not have clinically significant congenital, cardiopulmonary, or neurodevelopmental abnormalities underwent spirometry, exercise testing, and measurement of fractional exhaled nitric oxide before and after treatment. A total of 144 preterm-born children at the Children's Hospital for Wales in Cardiff, UK, were identified and enrolled between July 1, 2017, and August 31, 2019. Interventions: Each child was randomized to 1 of 3 cohorts: fluticasone propionate, 50 µg, with placebo; fluticasone propionate, 50 µg, with salmeterol, 25 µg; or placebo inhalers, all given as 2 puffs twice daily for 12 weeks. Children receiving preexisting ICS treatment underwent washout prior to randomization to ICS or ICS/LABA. Main Outcomes and Measures: The primary outcome was between-group differences assessed by adjusted pretreatment and posttreatment differences of %FEV1 using analysis of covariance. Intention-to-treat analysis was conducted. Results: Of 144 preterm-born children who were identified with %FEV1 less than or equal to 85%, 53 were randomized. Treatment allocation was 20 children receiving ICS (including 5 with prerandomization ICS), 19 children receiving ICS/LABA (including 4 with prerandomization ICS), and 14 children receiving placebo. The mean (SD) age of children was 10.8 (1.2) years, and 29 of the randomized children (55%) were female. The posttreatment %FEV1 was adjusted for sex, gestation, bronchopulmonary dysplasia, intrauterine growth restriction, pretreatment corticosteroid status, treatment group, and pretreatment values. Posttreatment adjusted means for %FEV1, using analysis of covariance, were 7.7% (95% CI, -0.27% to 15.72%; P = .16) higher in the ICS group and 14.1% (95% CI, 7.3% to 21.0%; P = .002) higher in the ICS/LABA group compared with the placebo group. Active treatment decreased the fractional exhaled nitric oxide and improved postexercise bronchodilator response but did not improve exercise capacity. One child developed cough when starting inhaler treatment; no other adverse events reported during the trial could be attributed to the inhaler treatment. Conclusions and Relevance: The results of this randomized clinical trial suggest that combined ICS/LABA treatment is beneficial for prematurity-associated lung disease in children. Trial Registration: EudraCT number: 2015-003712-20.

Barriers to Prescribing Opioids in the Management of Chronic Breathlessness in COPD: A Review.

In people with COPD breathlessness is a common symptom and if mistreated can result in poor physical health and reduced quality of life. While it is important to manage the breathlessness using non-pharmacological management, persistent breathlessness may be treated with opioids. However, some physicians are reluctant to prescribe opioids to manage breathlessness in COPD. The aim of this review is to report the views, attitudes and barriers (if any) of healthcare professionals towards using opioids to manage chronic breathlessness in COPD. A review of the relevant literature was undertaken, using CINAHL, ScienceDirect and PubMed databases. The selected literature was assessed for quality of study design and methods used. Eleven studies (three qualitative, three mixed-methods and five quantitative) were reviewed and three themes were identified. Opioid use for refractory breathlessness in COPD is likely under prescribed by health care professionals working in areas other than palliative care. Additionally, there is a lack of confidence in using opioids except in those with palliative care experience, who are more likely to believe opioids may be helpful. Barriers identified are a lack of training, education, inadequate guidelines and concerns surrounding respiratory depression and other side effects. Research on this topic is mainly comprised of interviews or surveys and is low to moderate quality. Further clinical trials are needed on this topic including the opinions of all prescribing health care professionals involved in the care of these patients. Additionally, guidelines should offer further advice on when to start opioids and which patients would benefit most from opioids.

The Development and Testing of a Chemotherapy-Induced Phlebitis Severity (CIPS) Scale for Patients Receiving Anthracycline Chemotherapy for Breast Cancer.

A chemotherapy induced phlebitis severity (CIPS) scale was developed in patients receiving anthracycline chemotherapy for breast cancer. A five-point severity scoring scale for chemotherapy-induced phlebitis was tested for inter-rater reliability. Ease of use was observed through timing assessments and a review of the completeness of documentation. A comparison of CIPS scale grade with participant reported severity scores was made. The final version was tested for inter-rater reliability, with 122 patient assessments. There was an 89.3% (109 of 122) agreement between the assessors (κ = 0.82, SE ± 0.042, 95% CI 0.74-0.90). Mean time to complete the scale was 1 min 36 s and documentation was fully completed for 98% of assessments. Patient reported severity closely matched the CIPS grade (κ = 0.54, SE ± 0.045, 95% CI 0.46-0.63). This new scale provides a list of symptoms associated with chemotherapy phlebitis, which can be scored quickly and accurately. It provides a reliable method for assessing chemotherapy-induced phlebitis, enabling a better understanding of its impact on patients' quality of life, and to inform the appropriate choice of peripheral or central intravenous administration. Multicentre testing of the CIPS scale is recommended.

Clinician perception of a novel cardiovascular lifestyle prescription form in the primary and secondary care setting in Wales, UK.

ISSUES ADDRESSED: To establish the views of clinicians on the feasibility and effectiveness of using a novel lifestyle prescription form (LRx) which requires co-signing by clinician and patient and is uniquely based on the design of the standard drug prescription form, in the primary and secondary health care settings. METHODS: Thirty-six participants were issued with a "prescription" pad, of 20 LRx scripts, for 1 month and requested to issue an LRx prescription to patients they deemed suitable during their consultation, recording their reason for use of the LRx. Each clinician was then asked to complete a comprehensive feedback questionnaire. RESULTS: Feedback of the LRx was overwhelmingly positive. The script was viewed as a more effective way to convey and support cardiovascular lifestyle advice, than usual care. Forty per cent (196 of 480) of the LRx scripts that were provided to primary and secondary care clinicians during the study period were issued. In most consultations, the LRx script was issued to reaffirm dietary advice. Nurses and health care assistants were more likely than doctors to use the LRx in response to a request for lifestyle advice from a patient. CONCLUSIONS: The LRx may be a useful addition to the clinician's communication toolkit to stimulate lifestyle behaviour changes in their patients. The main barrier to use in the study was lack of consultation time. SO WHAT?: Issuing the LRx is a method of solidifying lifestyle advice that clinicians could utilise, providing them with another tool in their behaviour change arsenal, particularly with familiarity with the tool.

Agreement between self-reported asthma symptoms and exhaled nitric oxide levels: impact on inhaled corticosteroid prescribing in general practice. An observational study.

BACKGROUND: The National Review of Asthma Deaths UK highlighted that 46% of deaths could be avoided and recommended that all sufferers receive a structured asthma annual review which assess asthma control. In primary care this is commonly achieved using symptom-based questionnaires such as the Asthma Control Test (ACT). A newer method of assessing asthma control is Fractional Exhaled Nitric Oxide (FeNO) testing, which is currently recommended for the diagnosis of asthma, but not for monitoring of asthma control. The study aim was to assess the correlation between self-reported symptoms as measured by the ACT and FeNO testing and the subsequent impact of FeNO testing on prescribing of asthma medication. METHODS: A retrospective review of 65 patients who had received both ACT and FeNO testing as part of their asthma annual review. A spearman correlation was used to estimate the correlation between ACT scores and FENO levels. A χ2 test was used to compare prompting frequency of the measures and Kendalls τ statistic was made to estimate their concordance and influence on subsequent ICS medication prescription. RESULTS: The mean age of the participants was 41 years (4-93 years). There was no statistically significant correlation between ACT and FeNO (ρ = 0.195, p = 0.120). The median FeNO was 26 ppb (range 8-279 ppb), and the ACT score 20 (range 5 to 25 points). Furthermore, FeNO more frequently prompts a change in medication than ACT, 66% versus 42% (p = 0.005). A low concordance between the measures was found (Kendall's τ statistic - 0.321). CONCLUSION: FeNO should be considered for monitoring of control in asthma. To balance the cost of implementing this technology into primary care a risk stratified approach could be applied to testing.

Home management of lower limb lymphoedema with an intermittent pneumatic compression device: a feasibility study.

BACKGROUND: Lymphoedema is a chronic condition that causes swelling in the body tissues. Presently, there is no cure for lymphoedema; instead, current treatment is aimed at lifelong management to help control symptoms. Intermittent pneumatic compression (IPC) therapy can be considered as an adjunct to standard lymphoedema care; however, research regarding the efficacy of this treatment modality is limited. METHODS: Twenty participants were recruited from an outpatient lymphoedema clinic (South Wales, UK) to a feasibility randomised control trial designed to evaluate the efficacy of an IPC device (LymphAssist, Huntleigh Healthcare) in reducing lower limb volume. The primary objective was to assess feasibility in terms of (1) study feasibility, including recruitment, retention and assessment of outcome measures, and (2) intervention feasibility, including intervention fidelity and acceptability to participants. Participants were randomly assigned to a control group (n = 10) or intervention group (n = 10). The control group received their standard lymphoedema care only for a 6-month period, whereas the intervention group received their standard lymphoedema care plus an IPC device to use for 6 months. A bilateral lower limb assessment and quality of life survey were undertaken at baseline and 3- and 6-month time points. RESULTS: The study recruited to target within the planned time frame with a retention rate of 80%. Issues relating to potential recruitment bias and study attrition were identified and possible solutions explored. In addition, supplementary primary outcome measures that are important to the study population were identified and will be incorporated into the design of future studies. CONCLUSION: This feasibility study identified that a larger randomised controlled trial investigating the efficacy of home use IPC devices is feasible with modifications to the study protocol. TRIAL REGISTRATION: This trial is registered with clinicaltrials.gov (NCT03825263).

Classification of Tidal Breathing Airflow Profiles Using Statistical Hierarchal Cluster Analysis in Idiopathic Pulmonary Fibrosis.

In idiopathic pulmonary fibrosis (IPF) breathing pattern changes with disease progress. This study aims to determine if unsupervised hierarchal cluster analysis (HCA) can be used to define airflow profile differences in people with and without IPF. This was tested using 31 patients with IPF and 17 matched healthy controls, all of whom had their lung function assessed using spirometry and carbon monoxide CO transfer. A resting tidal breathing (RTB) trace of two minutes duration was collected at the same time. A Euclidian distance technique was used to perform HCA on the airflow data. Four distinct clusters were found, with the majority (18 of 21, 86%) of the severest IPF participants (Stage 2 and 3) being in two clusters. The participants in these clusters exhibited a distinct minute ventilation (p < 0.05), compared to the other two clusters. The respiratory drive was greatest in Cluster 1, which contained many of the IPF participants. Unstructured HCA was successful in recognising different airflow profiles, clustering according to differences in flow rather than time. HCA showed that there is an overlap in tidal airflow profiles between healthy RTB and those with IPF. The further application of HCA in recognising other respiratory disease is discussed.

Automated plethysmographic measurement of the ankle-brachial index: a comparison with the doppler ultrasound method.

The ankle-brachial index is widely regarded as a pivotal tool for the diagnosis and quantification of peripheral arterial disease. It is, however, plagued by issues relating to its time consuming nature and the skills required to undertake its measurement using the gold standard Doppler ultrasound method. Automated ankle-brachial index measurement devices aim to address such issues; this study aimed to compare the performance of such a device with the Doppler method. Three hundred and eighty participants, with risk factors for cardiovascular disease (mean age: 64, 57% male), underwent ankle-brachial index measurement firstly with a plethysmographic device followed by the Doppler method. The mean difference between the two methods was 0.016±0.1, 95% limits of agreement:±0.2. Sensitivity for detection of peripheral arterial disease, as defined by Doppler ankle-brachial index⩽0.9, was 70%, specificity 96%, accuracy 94%. A receiver operating curve revealed an area under the curve of.96, with a 1.04 plethysmographic ankle-brachial index cutoff for optimal sensitivity (98%) and specificity (75%). Automated measurements were significantly faster than Doppler measurements (7 min 55 s vs. 17 min 45 s, respectively, P <0.01). Although is it unclear if the plethysmographic device has sufficient diagnostic accuracy to be used as a stand alone test for the diagnosis of peripheral arterial disease, it is concluded that it can be used as a fast and amenable method of identifying people who require further arterial assessment; the higher cutoff point of 1.04 should be used for this purpose.

Breath analysis: translation into clinical practice.

Breath analysis in respiratory disease is a non-invasive technique which has the potential to complement or replace current screening and diagnostic techniques without inconvenience or harm to the patient. Recent advances in ion mobility spectrometry (IMS) have allowed exhaled breath to be analysed rapidly, reliably and robustly thereby facilitating larger studies of exhaled breath profiles in clinical environments. Preliminary studies have demonstrated that volatile organic compound (VOC) breath profiles of people with respiratory disease can be distinguished from healthy control groups but there is a need to validate, standardise and ensure comparability between laboratories before real-time breath analysis becomes a clinical reality. It is also important that breath sampling procedures and methodologies are developed in conjunction with clinicians and the practicalities of working within the clinical setting are considered to allow the full diagnostic potential of these techniques to be realised. A protocol is presented, which has been developed over three years and successfully deployed for quickly and accurately collecting breath samples from 323 respiratory patients recruited from 10 different secondary health care clinics.

Current utility of the ankle-brachial index (ABI) in general practice: implications for its use in cardiovascular disease screening.

BACKGROUND: Peripheral arterial disease (PAD) is a marker of systemic atherosclerosis and associated with a three to six fold increased risk of death from cardiovascular causes. Furthermore, it is typically asymptomatic and under-diagnosed; this has resulted in escalating calls for the instigation of Primary Care PAD screening via Ankle Brachial Index (ABI) measurement. However, there is limited evidence regarding the feasibility of this and if the requisite core skills and knowledge for such a task already exist within primary care. This study aimed to determine the current utility of ABI measurement in general practices across Wales, with consideration of the implications for its use as a cardiovascular risk screening tool. METHOD: A self-reporting questionnaire was distributed to all 478 General Practices within Wales, sent via their responsible Health Boards. RESULTS: The survey response rate was 20%. ABI measurement is primarily performed by nurses (93%) for the purpose of wound management (90%). It is infrequently (73% < 4 times per month) and often incorrectly used (42% out of compliance with current ABI guidance). Only 52% of general practitioners and 16% of nurses reported that patients with an ABI of ≤ 0.9 require aggressive cardiovascular disease risk factor modification (as recommended by current national and international guidelines). CONCLUSION: ABI measurement is an under-utilised and often incorrectly performed procedure in the surveyed general practices. Prior to its potential adoption as a formalised screening tool for cardiovascular disease, there is a need for a robust training programme with standardised methodology in order to optimise accuracy and consistency of results. The significance of a diagnosis of PAD, in terms of associated increased cardiovascular risk and the necessary risk factor modification, needs to be highlighted.

Exercise-induced bronchoconstriction in school-aged children who had chronic lung disease in infancy.

OBJECTIVES: To assess for exercise-induced bronchoconstriction in 8- to 12-year-old children who had chronic lung disease (CLD) in infancy, and to evaluate the response of bronchoconstriction to bronchodilation with albuterol in comparison with preterm and term controls. STUDY DESIGN: Ninety-two children, including 29 with CLD, 33 born preterm at ≤32 weeks' gestation, and 30 born at term, underwent lung spirometry before and after cycle ergometry testing and after postexercise bronchodilation with albuterol. RESULTS: Doctor-diagnosed asthma and exercise-induced wheeze were reported more frequently in the CLD group than in the preterm and term groups, but only 10% were receiving a bronchodilator. There were no differences among the groups in peak minute ventilation, oxygen uptake, or carbon dioxide output at maximum exercise. After maximal exercise, predicted forced expiratory volume in 1 second (FEV1) decreased from a mean baseline value of 81.9% (95% CI, 76.6-87.0%) to 70.8% (95% CI, 65.5-76.1%) after exercise in the CLD group, from 92.0% (95% CI, 87.2-96.8%) to 84.3% (95% CI, 79.1-89.4%) in the preterm group, and from 97.5% (95% CI, 92.5-102.6%) to 90.3% (95% CI, 85.1-95.5%) in the term group. After albuterol administration, FEV1 increased to 86.8% (95% CI, 81.7-92.0%) in the CLD group, 92.1% (95% CI, 87.3-96.9%) in the preterm group, and 97.1% (95% CI, 92.0-102.3%) in the term group. The decrease in predicted FEV1 after exercise and increase in predicted FEV1 after bronchodilator use were greatest in the CLD group (-11.0% [95% CI, -18.4 to -3.6%] and 16.0% [95% CI, 8.6-23.4%], respectively; P < .005 for both), with differences of <8% in the 2 control groups. CONCLUSION: School-age children who had CLD in infancy had significant exercise-induced bronchoconstriction that responded significantly to bronchodilation. Reversible exercise-induced bronchoconstriction is common in children who experienced CLD in infancy and should be actively assessed for and treated.

The respiratory time and flow profile at volitional exercise termination.

In this study, we examine the effect of exercise on the time and flow characteristics of the respiratory cycle profile at the point of volitional exercise termination. Eight males (mean age 29 years, s = 10; body mass 74 kg, s = 7; height 1.75 m, s = 0.04) undertook a cycle test to volitional exhaustion on a cycle ergometer, which allowed peak oxygen uptake (VO(2peak)) to be measured (mean 51 ml x kg(-1) x min(-1), s = 7). At a later date, two sub-maximal tests to volitional exhaustion were completed in a random order at 76% (s = 6) and 86% VO(2peak) (s = 7). As expected, the magnitude of the respiratory flow and time characteristics varied with the three exercise intensities, as did the point of exercise termination and terminal ventilation rates, which varied from 7 to 27 min and 112 to 132 litres x min(-1) respectively. More importantly, however, at exercise termination some of the characteristics were similar, particularly the breathing frequency (at termination 49 breaths x min(-1)), the ratio between inspiration and total breath time (0.5), and the later occurrence of peak inspiratory flow (0.24-0.48 s). The coincident unity of these time and flow profile characteristics at exercise termination illustrates how the integration of timing and flow during breathing influence exercise capacity in non-elite athletes.

Acute cardio-respiratory changes induced by hyperpnoea using a respiratory muscle trainer.

The aim of this study was to examine the cardio-respiratory effects of voluntary hyperpnoea using a respiratory muscle trainer (RMT) with three different sized rebreathing bags. In particular, the effects of hyperpnoea on inspired and end-tidal gas concentrations were determined. Seven adult males completed three 30 min bouts of hyperpnoea using optimal, oversized and undersized rebreathing bags. Inspired (F(I)) and expired end-tidal (F(ET)) O2 and CO2 concentrations, arterial O2 saturation (S(AO2)) and heart rate were measured during hyperpnoea. Before and after a bout of hyperpnoea, pulmonary function and blood pressure (BP) were assessed. Data were analysed using a two-way repeated-measures ANOVA, with p < 0.05 considered significant. Three subjects experienced discomfort during hyperpnoea and stopped after 20 min. During hyperpnoea, the F(ETCO2) was maintained at 4.6 +/- 0.7% irrespective of bag size. The increase in F(ICO2) over time reached 0.5 +/- 0.5% at 20 min. The F(IO2) fell to 19.4 +/- 0.8% at 20 min, and S(AO2) decreased to 97%. Heart rate and systolic BP increased slightly, but independently of rebreathing bag volume. No changes in pulmonary function or diastolic BP were found. It is concluded that the RMT maintained a constant F(ETCO2) at the expense of a mild hypoxia. The acute effects of hyperpnoea on the cardio-respiratory system are generally mild, but not always tolerable for 30 min.

Changes in lung function and tidal airflow patterns after increasing extrathoracic airway resistance.

OBJECTIVE: The aim of this study was to determine what changes occur in previously described tidal expiratory flow patterns when extrathoracic resistance is added. METHODOLOGY: A total of 16 subjects with normal lung function and 15 patients with chronic COPD, were studied. The following measurements were made before and after the addition of an extrathoracic expiratory resistance (EER; 0.89 kPa/L s at a flow of 0.5 L/s) during uncoached tidal breathing: expiratory time (tE), frequency (f), expiratory time to maximum flow/total expiratory time (tPTEF/tE), tidal maximum expiratory flow (PEF(TIDAL)), and time constant of the respiratory system calculated from the passive portion of tidal expiration (trs(TIDAL)). Post peak profiles were categorized as convex, linear or concave and time for flow to fall to 80% and 20% of maximum (t80 and t20) were measured. RESULTS: Tidal indices tE, f and PEF(TIDAL), were similar in the two groups, but tPTEF/tE was greater and trs(TIDAL) was less in the normal subjects than in the COPD patients. Addition of EER in both groups caused PEF(TIDAL) to decrease and trs(TIDAL), t80 and the percentage of convex profiles to increase. tPTEF/tE increased in the COPD patients but was unchanged in the control group. CONCLUSION: After addition of EER during tidal breathing, expiratory flow in COPD patients resembled that seen in normal subjects.

Analysis of tidal breathing profiles in cystic fibrosis and COPD.

STUDY OBJECTIVES: To explore the flow and time domain characteristics of resting tidal airflow profiles in the presence of obstructive airway disease. METHODS: Spirometry was performed on 81 adults and 46 juveniles in the lung function laboratory. All the juveniles had cystic fibrosis (CF), as did some of the adults (n = 25), with the remainder having either healthy lungs or COPD. Resting breathing profiles were recorded using a pneumotachograph. Thirteen flow and time domain parameters were extracted from each profile. Two new indexes were derived that are influenced by the shape of the post-peak expiratory flow portion of the expirogram. In this expirogram, the first index (change in post-peak expiratory flow at time 20% [TPPEF(20)]) describes early changes in post-peak flow, while the second index (change in post-peak expiratory flow at time 80% [TPPEF(80)]) describes later changes in flow. Multiple linear regression techniques were used to define the relationship between body size, flow and time domain parameters, and FEV(1), a measure of obstructive airway disease. RESULTS: In juvenile subjects with CF, body weight and the time to reach peak expiratory flow are the main correlates with FEV(1) (adjusted r(2) = 0.74). The adult CF group are different with the expiratory flow index (TPPEF(20)) being the major correlate with FEV(1) (adjusted r(2) = 0.77). In the COPD group, the second expiratory flow index (TPPEF(80)) is the major correlate instead (adjusted r(2) = 0.6). CONCLUSIONS: Using multiple linear regression techniques has allowed the description of the interrelationships between body size, age, and tidal breathing profile in obstructive airway disease. The relationship between the flow indexes TPPEF(20) and TPPEF(80) show that in adults with CF, the loss of expiratory flow braking is an important adaptation to disease, while in COPD pulmonary hyperinflation is the predominant factor.