Eastern Australian Farmers Managing and Thinking Differently: Innovative Adaptation Cycles.

The uncertainty of climate change is a significant challenge prompting Australian farmers to create different thinking and different management systems that ensure sustained farm business viability and continuity, particularly in extreme environments. The purpose of this study was to explore the conditions and adaptive processes for managing farm resilience and cyclic adaptation pathways, in response to climate change. A positive deviance sample of farmers was interviewed, and data was collected from a cohort of twenty-two climate change innovators across Eastern Australia. Grounded theory analysis of data identified three processes and two transactional maps of climate change adaptation, in this under studied farmer cohort. The development of the transactional maps found the resilience and preparedness processes as adaptive learning responses to the stressors of climate change. The processes of managing the business and resources were identified as markers of preparedness and resilience that ensured business viability and continuity. Farmers prepared for climate change through transforming make-over processes as an adaptive learning response to climate challenges. Mapping the cycle of adaptation identified the processes of socio-cognitive agency, learning from feedback and consequences, and contextual variables as critical elements of adaptation. The intervening socio-ecological processes of intelligence gathering and influencing, and socio-cognitive precursors, were found to regulate the adaptation cycle. The cycle was found to have both incremental and transformative transmission processes, and intervening processes of climate and contextual variables. The changing patterns and extremes of climate change were found to impact the growing season, and its potential, as unique variables that demand farm adaptation. Ultimately, this study identified potential points of influence for leveraging preparedness behaviours.

Impact of respiratory muscle training on respiratory muscle strength, respiratory function and quality of life in individuals with tetraplegia: a randomised clinical trial.

BACKGROUND: Respiratory complications remain a leading cause of morbidity and mortality in people with acute and chronic tetraplegia. Respiratory muscle weakness following spinal cord injury-induced tetraplegia impairs lung function and the ability to cough. In particular, inspiratory muscle strength has been identified as the best predictor of the likelihood of developing pneumonia in individuals with tetraplegia. We hypothesised that 6 weeks of progressive respiratory muscle training (RMT) increases respiratory muscle strength with improvements in lung function, quality of life and respiratory health. METHODS: Sixty-two adults with tetraplegia participated in a double-blind randomised controlled trial. Active or sham RMT was performed twice daily for 6 weeks. Inspiratory muscle strength, measured as maximal inspiratory pressure (PImax) was the primary outcome. Secondary outcomes included lung function, quality of life and respiratory health. Between-group comparisons were obtained with linear models adjusting for baseline values of the outcomes. RESULTS: After 6 weeks, there was a greater improvement in PImax in the active group than in the sham group (mean difference 11.5 cmH2O (95% CI 5.6 to 17.4), p<0.001) and respiratory symptoms were reduced (St George Respiratory Questionnaire mean difference 10.3 points (0.01-20.65), p=0.046). Significant improvements were observed in quality of life (EuroQol-Five Dimensional Visual Analogue Scale 14.9 points (1.9-27.9), p=0.023) and perceived breathlessness (Borg score 0.64 (0.11-1.17), p=0.021). There were no significant improvements in other measures of respiratory function (p=0.126-0.979). CONCLUSIONS: Progressive RMT increases inspiratory muscle strength in people with tetraplegia, by a magnitude which is likely to be clinically significant. Measurement of baseline PImax and provision of RMT to at-risk individuals may reduce respiratory complications after tetraplegia. TRIAL REGISTRATION NUMBER: Australian New Zealand Clinical Trials Registry (ACTRN 12612000929808).

Effect of 1†month of zopiclone on obstructive sleep apnoea severity and symptoms: a randomised controlled trial.

Hypnotic use in obstructive sleep apnoea (OSA) is contraindicated due to safety concerns. Recent studies indicate that single-night hypnotic use worsens hypoxaemia in some and reduces OSA severity in others depending on differences in pathophysiology. However, longer clinical trial data are lacking. This study aimed to determine the effects of 1 month of zopiclone on OSA severity, sleepiness and alertness in patients with low-moderate respiratory arousal thresholds without major overnight hypoxaemia.69 participants completed a physiology screening night with an epiglottic catheter to quantify arousal threshold. 30 eligible patients (apnoea-hypopnoea index (AHI) 22±11 events·h-1) then completed standard in-laboratory polysomnography (baseline) and returned for two additional overnight sleep studies (nights 1 and 30) after receiving either nightly zopiclone (7.5 mg) or placebo during a 1-month, double-blind, randomised, parallel trial (ANZCTR identifier ANZCTRN12613001106729).The change in AHI from baseline to night 30 was not different between zopiclone versus placebo groups (-5.9±10.2 versus -2.4±5.5 events·h-1; p=0.24). Similarly, hypoxaemia, next-day sleepiness and driving simulator performance were not different.1 month of zopiclone does not worsen OSA severity, sleepiness or alertness in selected patients without major overnight hypoxaemia. As the first study to assess the effect of a hypnotic on OSA severity and sleepiness beyond single-night studies, these findings provide important safety data and insight into OSA pathophysiology.

Advances in Remote Respiratory Assessments for People with Chronic Obstructive Pulmonary Disease: A Systematic Review.

BACKGROUND: Chronic obstructive pulmonary disease (COPD) is a leading cause of mortality. Advances in remote technologies and telemedicine provide new ways to monitor respiratory function and improve chronic disease management. However, telemedicine does not always include remote respiratory assessments, and the current state of knowledge for people with COPD has not been evaluated. OBJECTIVE: Systematically review the use of remote respiratory assessments in people with COPD, including the following questions: What devices have been used? Can acute exacerbations of chronic obstructive pulmonary disease (AECOPD) be predicted by using remote devices? Do remote respiratory assessments improve health-related outcomes? MATERIALS AND METHODS: The review protocol was registered (PROSPERO 2016:CRD42016049333). MEDLINE, EMBASE, and COMPENDEX databases were searched for studies that included remote respiratory assessments in people with COPD. A narrative synthesis was then conducted by two reviewers according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. RESULTS: Fifteen studies met the inclusion criteria. Forced expiratory volume assessed daily by using a spirometer was the most common modality. Other measurements included resting respiratory rate, respiratory sounds, and end-tidal carbon dioxide level. Remote assessments had high user satisfaction. Benefits included early detection of AECOPD, improved health-related outcomes, and the ability to replace hospital care with a virtual ward. CONCLUSION: Remote respiratory assessments are feasible and when combined with sufficient organizational backup can improve health-related outcomes in some but not all cohorts. Future research should focus on the early detection, intervention, and rehabilitation for AECOPD in high-risk people who have limited access to best care and investigate continuous as well as intermittent monitoring.

Role of common hypnotics on the phenotypic causes of obstructive sleep apnoea: paradoxical effects of zolpidem.

Hypnotics are contraindicated in obstructive sleep apnoea (OSA) because of concerns of pharyngeal muscle relaxation and delayed arousal worsening hypoxaemia. However, human data are lacking. This study aimed to determine the effects of three common hypnotics on the respiratory arousal threshold, genioglossus muscle responsiveness and upper airway collapsibility during sleep.21 individuals with and without OSA (18-65 years) completed 84 detailed sleep studies after receiving temazepam (10 mg), zolpidem (10 mg), zopiclone (7.5 mg) and placebo on four occasions in a randomised, double-blind, placebo-controlled, crossover trial (ACTRN12612001004853).The arousal threshold increased with zolpidem and zopiclone versus placebo (mean±sd -18.3±10 and -19.1±9 versus -14.6±7 cmH2O; p=0.02 and p<0.001) but not with temazepam (-16.8±9 cmH2O; p=0.17). Genioglossus muscle activity during stable non-REM sleep and responsiveness during airway narrowing was not different with temazepam and zopiclone versus placebo but, paradoxically, zolpidem increased median muscle responsiveness three-fold during airway narrowing (median -0.15 (interquartile range -1.01 to -0.04) versus -0.05 (-0.29 to -0.03)% maximum EMG per cmH2O epiglottic pressure; p=0.03). The upper airway critical closing pressure did not change with any of the hypnotics.These doses of common hypnotics have differential effects on the respiratory arousal threshold but do not reduce upper airway muscle activity or alter airway collapsibility during sleep. Rather, muscle activity increases during airway narrowing with zolpidem.

Home-based telerehabilitation via real-time videoconferencing improves endurance exercise capacity in patients with COPD: The randomized controlled TeleR Study.

BACKGROUND AND OBJECTIVE: Telerehabilitation has the potential to increase access to pulmonary rehabilitation (PR) for patients with COPD who have difficulty accessing centre-based PR due to poor mobility, lack of transport and cost of travel. We aimed to determine the effect of supervised, home-based, real-time videoconferencing telerehabilitation on exercise capacity, self-efficacy, health-related quality of life (HRQoL) and physical activity in patients with COPD compared with usual care without exercise training. METHODS: Patients with COPD were randomized to either a supervised home-based telerehabilitation group (TG) that received exercise training three times a week for 8 weeks or a control group (CG) that received usual care without exercise training. Outcomes were measured at baseline and following the intervention. RESULTS: Thirty-six out of 37 participants (mean ± SD age = 74 ± 8 years, forced expiratory volume in 1 s (FEV1 ) = 64 ± 21% predicted) completed the study. Compared with the CG, the TG showed a statistically significant increase in endurance shuttle walk test time (mean difference = 340 s (95% CI: 153-526, P < 0.001)), an increase in self-efficacy (mean difference = 8 points (95% CI: 2-14, P < 0.007)), a trend towards a statistically significant increase in the Chronic Respiratory Disease Questionnaire total score (mean difference = 8 points (95% CI: -1 to 16, P = 0.07)) and no difference in physical activity (mean difference = 475 steps per day (95% CI: -200 to 1151, P = 0.16)). CONCLUSION: This study showed that telerehabilitation improved endurance exercise capacity and self-efficacy in patients with COPD when compared with usual care.

Physical activity levels improve following discharge in people admitted to hospital with an acute exacerbation of chronic obstructive pulmonary disease.

This study aimed to determine the physical activity level of people admitted to hospital with an acute exacerbation of chronic obstructive pulmonary disease (AECOPD) and whether physical activity changed immediately after discharge and 6 weeks post hospital admission. In this prospective observational study, people admitted to hospital with an AECOPD had physical activity levels monitored using the SenseWear(®) Armband (model MF-SW) for 3 days in hospital (T1), during the first week at home following discharge (T2), and at home during the sixth week after admission (T3). Fifty participants (mean age (SD) 71 (10) years) completed the study. There was a linear increase in average steps per day over the three time periods (T1, mean (SD) 1385 (1972) steps/day; T2, 2040 (2680); T3, 2328 (2745); analysis of variance (ANOVA) p = 0.001) and time spent in moderate activity (3.0-6.0 metabolic equivalents; minutes/day) (T1, mean (SD) 16 (27) minutes/day; T2, 32 (46) minutes/day; T3, 35 (58) minutes/day; ANOVA p = 0.008). For both outcomes, post hoc t-tests showed significant improvements from T1 to T2 and from T1 to T3, but not between T2 and T3. Physical activity was low in hospital and significantly improved in the week after discharge but showed no further significant improvement at 6 weeks following a hospitalized AECOPD.

Brain stem activity changes associated with restored sympathetic drive following CPAP treatment in OSA subjects: a longitudinal investigation.

Obstructive sleep apnea (OSA) is associated with significantly elevated muscle sympathetic nerve activity (MSNA), leading to hypertension and increased cardiovascular morbidity. Although little is known about the mechanisms responsible for the sympathoexcitation, we have recently shown that the elevated MSNA in OSA is associated with altered neural processing in various brain stem sites, including the dorsolateral pons, rostral ventrolateral medulla, medullary raphe, and midbrain. Given the risk associated with elevated MSNA, we aimed to determine if treatment of OSA with continuous positive airway pressure (CPAP) would reduce the elevated MSNA and reverse the brain stem functional changes associated with the elevated MSNA. We performed concurrent recordings of MSNA and blood oxygen level-dependent (BOLD) signal intensity of the brain stem, using high-resolution functional magnetic resonance imaging, in 15 controls and 13 subjects with OSA, before and after 6 mo CPAP treatment. As expected, 6 mo of CPAP treatment significantly reduced MSNA in subjects with OSA, from 54 ± 4 to 23 ± 3 bursts/min and from 77 ± 7 to 36 ± 3 bursts/100 heart beats. Importantly, we found that MSNA-coupled changes in BOLD signal intensity within the dorsolateral pons, medullary raphe, and rostral ventrolateral medulla returned to control levels. That is, CPAP treatment completely reversed brain stem functional changes associated with elevated MSNA in untreated OSA subjects. These data highlight the effectiveness of CPAP treatment in reducing one of the most significant health issues associated with OSA, that is, elevated MSNA and its associated elevated morbidity.

Brainstem changes associated with increased muscle sympathetic drive in obstructive sleep apnoea.

Obstructive sleep apnoea (OSA) is associated with significantly increased bursts of muscle sympathetic nerve activity (MSNA), leading to hypertension and increased cardiovascular morbidity. The underlying mechanism responsible for this sympathoexcitation is unknown. The aim of this investigation was to determine brainstem sites that contribute to this increased on-going muscle vasoconstrictor drive. We measured regional grey matter volume using voxel-based morphometry of T1-weighted anatomical images in 20 subjects with OSA and 19 healthy age-matched controls. We also performed concurrent recordings of MSNA and Blood Oxygen Level Dependent (BOLD) signal intensity of the brainstem, using high-resolution functional magnetic resonance imaging, in 15 subjects with OSA and 15 controls. OSA subjects had significantly elevated MSNA, which was correlated to altered BOLD signal intensity changes in the dorsolateral pons, rostral ventrolateral medulla, medullary raphe and midbrain. The medullary raphe, rostroventrolateral medulla and dorsolateral pons also had significantly increased grey matter volumes in subjects with obstructive sleep apnoea compared with controls. Furthermore, we also found that obstructive sleep apnoea was associated with increases in grey matter volume in the region of the hypoglossal nucleus. These data suggest that the elevated muscle vasoconstrictor drive in obstructive sleep apnoea may result from functional and anatomical changes within the dorsolateral pons, rostroventrolateral medulla and medullary raphe. These brainstem regions are known to modulate sympathetic output either directly or indirectly via sympathetic preganglionic neurons within the spinal cord. In addition, the known increase in genioglossus muscle activity in OSA may reflect the increase in grey matter volume of the hypoglossal nucleus.

Respiratory modulation of muscle sympathetic nerve activity in obstructive sleep apnoea.

Obstructive sleep apnoea (OSA) is associated with elevated muscle sympathetic nerve activity (MSNA) during normoxic daytime wakefulness, leading to hypertension. We tested the hypothesis that respiratory­sympathetic coupling, postulated to be the underlying cause of neurogenic hypertension, is increased in OSA. Muscle sympathetic nerve activity, blood pressure, ECG and respiration were recorded in 21 normotensive control subjects and 21 newly diagnosed patients with OSA before and after 6 and 12 months of treatment with continuous positive airway pressure. Muscle sympathetic nerve activity was recorded via tungsten microelectrodes inserted percutaneously into the peroneal nerve. Cardiac and respiratory modulation of MSNA was quantified from the cross-correlation histograms constructed between the sympathetic spikes and either ECG or respiration. Muscle sympathetic nerve activity was significantly elevated in newly diagnosed OSA patients compared with control subjects (53 ± 2 versus 28 ± 2 bursts min−1). There was a significant fall in MSNA after 6 months of continuous positive airway pressure (37 ± 2 bursts min−1), with no further change after 12 months (37 ± 2 bursts min−1). There were no significant differences in the magnitude of respiratory modulation of MSNA between the OSA patients and control subjects (40 ± 3.1 versus 39 ± 3.4%). However, when considering the normalized temporal profile there were changes in the respiratory patterning of MSNA in OSA, with more activity occurring in postinspiration and less in inspiration and expiration. This was largely reversed following long-term continuous positive airway pressure.

Physical comorbidities affect physical activity in chronic obstructive pulmonary disease: a prospective cohort study.

BACKGROUND AND OBJECTIVE: The prevalence of physical comorbidities such as obesity, musculoskeletal or neurological conditions in people with chronic obstructive pulmonary disease (COPD) is high, yet little is known about the impact of these physical comorbidities on physical activity. The primary aim of the study was to compare the physical activity levels of people with COPD with physical comorbidities (COPD + PC) to people with COPD without physical comorbidities (COPD) and healthy age-matched volunteers (control group). METHODS: Twenty-five people with COPD + PC (mean (standard deviation (SD)) age 73 (11) years, Global Initiative for Chronic Obstructive Lung Disease (GOLD) stage II-IV), 25 people with COPD (70 (8) years, GOLD stage II-IV) and 25 controls (70 (7) years) wore the SenseWear Pro3 Armband for 7 days. RESULTS: Engagement in light intensity physical activity (1.5-3.0 metabolic equivalents (MET)) (140 (76) minutes per day (min/day)) and moderate intensity physical activity (3.0-6.0 MET) (25 (35) min/day) in the COPD + PC group was significantly reduced compared with the COPD (231 (76) and 104 (106), respectively) and control group (259 (75) and 114 (57), respectively). In the 16 daytime hours between 6 am and 10 pm, people with COPD + PC spent a mean (SD) of 771 (98) min/day engaged in sedentary behaviour (<1.5 MET). This was significantly greater than the group with COPD (603 (148) min/day) and the control group (567 (76) min/day) (P < 0.001). CONCLUSIONS: People with COPD + PC had significantly lower daily physical activity levels compared with people with COPD without physical comorbidities and healthy people.

Water-based exercise in COPD with physical comorbidities: a randomised controlled trial.

Land-based exercise is often difficult for people with chronic obstructive pulmonary disease (COPD) who have coexisting obesity or musculoskeletal or neurological conditions. This randomised controlled trial aimed to determine the effectiveness of water-based exercise training in improving exercise capacity and quality of life compared to land-based exercise training and control (no exercise) in people with COPD and physical comorbidities. Participants referred to pulmonary rehabilitation were randomly allocated to a water-based exercise, land-based exercise or the control group. The two exercise groups trained for 8 weeks, completing three sessions per week. 45 out of 53 participants (mean ± SD age 72 ± 9 years; forced expiratory volume in 1 s 59 ± 15% predicted) completed the study. Compared to controls, water-based exercise training significantly increased 6-min walking distance, incremental and endurance shuttle walk distances, and improved Chronic Respiratory Disease Questionnaire (CRDQ) dyspnoea and fatigue. Compared to land-based exercise training, water-based exercise training significantly increased incremental shuttle walk distance (mean difference 39 m, 95% CI 5-72 m), endurance shuttle walk distance (mean difference 228 m, 95% CI 19-438 m) and improved CRDQ fatigue. Water-based exercise training was significantly more effective than land-based exercise training and control in increasing peak and endurance exercise capacity and improving aspects of quality of life in people with COPD and physical comorbidities.

Water-based exercise training for chronic obstructive pulmonary disease.

BACKGROUND: Land-based exercise training improves exercise capacity and quality of life in people with chronic obstructive pulmonary disease (COPD). Water-based exercise training is an alternative mode of physical exercise training that may appeal to the older population attending pulmonary rehabilitation programmes, those who are unable to complete land-based exercise programmes and people with COPD with comorbid physical and medical conditions. OBJECTIVES: To assess the effects of water-based exercise training in people with COPD. SEARCH METHODS: A search of the Cochrane Airways Group Specialised Register of trials, which is derived from systematic searches of bibliographic databases, including the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, CINAHL, AMED and PsycINFO, was conducted (from inception to August 2013). Handsearching was done to identify further qualifying studies from reference lists of relevant studies. SELECTION CRITERIA: Review authors included randomised or quasi-randomised controlled trials in which water-based exercise training of at least four weeks' duration was compared with no exercise training or any other form of exercise training in people with COPD. Swimming was excluded. DATA COLLECTION AND ANALYSIS: We used standard methodological procedures expected by The Cochrane Collaboration. MAIN RESULTS: Five studies were included with a total of 176 participants (71 people participated in water-based exercise training and 54 in land-based exercise training; 51 completed no exercise training). All studies compared supervised water-based exercise training versus land-based exercise training and/or no exercise training in people with COPD (with average forced expiratory volume in one second (FEV1) %predicted ranging from 39% to 62%). Sample sizes ranged from 11 to 53 participants. The exercise training programmes lasted from four to 12 weeks, and the mean age of participants ranged from 57 to 73 years. A moderate risk of bias was due to lack of reporting of randomisation, allocation and blinding procedures in some studies, as well as small sample sizes.Compared with no exercise, water-based exercise training improved the six-minute walk distance (mean difference (MD) 62 metres; 95% confidence interval (CI) 44 to 80 metres; three studies; 99 participants; moderate quality evidence), the incremental shuttle walk distance (MD 50 metres; 95% CI 20 to 80 metres; one study; 30 participants; high quality evidence) and the endurance shuttle walk distance (MD 371 metres; 95% CI 121 to 621 metres; one study; 30 participants; high quality evidence). Quality of life was also improved after water-based exercise training compared with no exercise (standardised mean difference (SMD) -0.97, 95% CI -0.37 to -1.57; two studies; 49 participants; low quality evidence). Compared with land-based exercise training, water-based exercise training did not significantly change the six-minute walk distance (MD 11 metres; 95% CI -11 to 33 metres; three studies; 62 participants; moderate quality evidence) or the incremental shuttle walk distance (MD 9 metres; 95% CI -15 to 34 metres; two studies; 59 participants; low quality evidence). However, the endurance shuttle walk distance improved following water-based exercise training compared with land-based exercise training (MD 313 metres; 95% CI 232 to 394 metres; two studies; 59 participants; moderate quality evidence). No significant differences were found between water-based exercise training and land-based exercise training for quality of life, as measured by the St George's Respiratory Questionnaire or by three of four domains of the Chronic Respiratory Disease Questionnaire (CRDQ); however, the fatigue domain of the CRDQ showed a statistically significant difference in favour of water-based exercise (MD -3.00; 95% CI -5.26 to -0.74; one study; 30 participants). Only one study reported long-term outcomes after water-based exercise training for quality of life and body composition, and no significant change was observed between baseline results and six-month follow-up results. One minor adverse event was reported for water-based exercise training (based on reporting from two studies; 20 participants). Impact of disease severity could not be examined because data were insufficient. AUTHORS' CONCLUSIONS: There is limited quality evidence that water-based exercise training is safe and improves exercise capacity and quality of life in people with COPD immediately after training. There is limited quality evidence that water-based exercise training offers advantages over land-based exercise training in improving endurance exercise capacity, but we remain uncertain as to whether it leads to better quality of life. Little evidence exists examining the long-term effect of water-based exercise training.

Is there a case for diaphragm pacing for amyotrophic lateral sclerosis patients?

Respiratory pacing has advanced the long-term management of respiratory failure secondary to neurological disorders. It has an established role in curtailing invasive mechanical ventilation after upper motor neuron lesions such as spinal cord injury. There is increasing interest to expand the application of intramuscular diaphragm pacing to amyotrophic lateral sclerosis (ALS), a progressive and fatal neurodegenerative disease. Although diaphragm pacing has been offered to ALS patients, evidence-based data to determine its benefits remain lacking. The limited current literature indicates progression of respiratory dysfunction in ALS patients despite diaphragm pacing. The data from clinical trials are inadequate to substantiate its survival and sleep benefits. Its advantages over non-invasive mechanical ventilation have not been directly investigated. Furthermore, there are cautions for ALS patients to consider when opting for diaphragm pacing. Progressive degeneration of the phrenic motor neurons in classic ALS will interrupt the transmission of pacer signals to sustain diaphragm contractions. Pacing protocols that are safe for other neurological conditions may be detrimental for ALS, at least as suggested by transgenic animal models. Issues inherent to the device warrant expert intervention in implanted patients. At present, clinical effectiveness and long-term safety concerns about diaphragm pacing in ALS remain to be addressed.

Firing probability and mean firing rates of human muscle vasoconstrictor neurones are elevated during chronic asphyxia.

Elevated muscle sympathetic nerve activity (MSNA) features in many cardiovascular diseases, but how this sympathoexcitation is brought about differs across pathologies. Unitary recordings from post-ganglionic muscle vasoconstrictor neurones in human subjects have shown that the augmented MSNA in the obstructive sleep apnoea syndrome (OSAS) is associated with an increase in firing probability and mean firing rate, and an increase in multiple within-burst firing. Here we characterize the firing properties of muscle vasoconstrictor neurones in patients with chronic obstructive pulmonary disease (COPD), who are chronically asphyxic. We tested the hypothesis that this elevated chemical drive would shift the firing pattern from that seen in healthy subjects to that seen in OSAS. The mean firing probability (52%) and mean firing rate (0.92 Hz) of 17 muscle vasoconstrictor neurones recorded in COPD were comparable to those previously recorded in OSAS (51% and 0.96 Hz), but significantly higher than those recorded in a group of healthy subjects with high levels of resting MSNA (35% and 0.33 Hz). In COPD single neurones fired once in 63% of cardiac intervals, comparable to OSAS (59%), but significantly lower than in the healthy group (78%). Conversely, single neurones fired twice in 25% of cardiac intervals, similar to OSAS (27%), but significantly higher than in the healthy group (18%). We conclude that the chronic asphyxia associated with COPD results in an increase in the firing probability and mean firing frequency of muscle vasoconstrictor neurones and causes a shift towards multiple firing, reflecting an increase in central muscle vasoconstrictor drive.

Colour change in cyanosis and the confusions of congenital colour vision deficient observers.

Visual recognition of cyanosis is an important clinical activity. While pulse oximetry is almost universal in the hospital environment, there are circumstances where it is not available or may be unreliable. Cyanosis recognition is affected by lighting colour. In addition, there is, mainly anecdotal, evidence that people with greater colour vision deficiencies (CVDs) have particular difficulty and there is no effective lighting strategy to assist in the observation. The change of blood colour with oxygenation has been shown to lie close to the direction of colour confusions made by congenital red-green dichromats. The important sites of observation are lips, nail beds and palm creases. 10 subjects who were known to be chronically hypoxaemic were recruited from the chronic respiratory program. Their blood oxygen saturation (SpO(2)) varied from 84% to 96% pre-exercise, and 61-84% post-exercise. Ten normal subjects were recruited whose SpO(2) was 99% or 100%. The spectral radiances of lips, nail beds and palm creases were measured using a telespectroradiometer and compared with the spectral radiances of a white tile of known spectral reflectances measured in the same location. This is a non-contact method of measurement, avoiding the blanching caused by pressure of contact methods. The spectral reflectances were calculated, and the chromaticities calculated for a Planckian radiator T = 4000K. Measurements on lips yielded the most consistent results. The colour changes pre- and post-exercise and compared with normal colour lie generally along a deutan confusion line. These results show the direction of the colour change and confirm the, previously anecdotal, difficulties in detecting cyanosis by observers with CVDs.

Bubble-positive expiratory pressure device and sputum clearance in bronchiectasis: A randomised cross-over study.

OBJECTIVES: The bubble-positive expiratory pressure (PEP) device may be used for sputum clearance in people with daily sputum production. However, this device has never been studied in people with bronchiectasis. Hence, the objective of this study was to compare the effect of bubble-PEP device, the active cycle of breathing technique (ACBT) and no intervention (control) on sputum clearance in people with bronchiectasis. METHODS: This was a prospective, randomised cross-over trial with concealed allocation, assessor blinding and intention-to-treat analysis. Adult participants with stable bronchiectasis and productive of sputum daily were recruited. Participants performed 30-min of bubble-PEP, ACBT or control in random order whilst sitting, followed by 60-min of quiet sitting, on three separate days at the same time within a 10-day period. Primary outcome measure was wet weight of expectorated sputum during 30-min intervention, 60-min post intervention and total wet weight (30 min plus 60 min). RESULTS: Thirty-five-participants (11 males, mean [standard deviation] age 75 [8] years, forced expiratory volume in 1 s 72 [20] % predicted) were recruited and 34 completed the study. There was no significant difference in sputum wet weight between bubble-PEP and ACBT during 30-min intervention (mean difference [95% confidence interval]) -0.59 g [-1.37, 0.19] and total wet weight (0.74 g [-0.54, 2.02]). Sputum wet weight was significantly greater in bubble-PEP than ACBT at 60-min post intervention (1.33 g [0.19, 2.47]). CONCLUSION: Sputum wet weight was significantly greater with bubble-PEP than control at all time periods, and greater than ACBT at 60-min-post. Bubble-PEP could be considered an alternative sputum clearance technique to ACBT.

Respiratory muscle function and activation in chronic obstructive pulmonary disease.

Inspiratory muscles are uniquely adapted for endurance, but their function is compromised in chronic obstructive pulmonary disease (COPD) due to increased loads, reduced mechanical advantage, and increased ventilatory requirements. The hyperinflation of COPD reduces the flow and pressure-generating capacity of the diaphragm. This is compensated by a threefold increase in neural drive, adaptations of the chest wall and diaphragm shape to accommodate the increased volume, and adaptations of muscle fibers to preserve strength and increase endurance. Paradoxical indrawing of the lower costal margin during inspiration in severe COPD (Hoover's sign) correlates with high inspiratory drive and severe airflow obstruction rather than contraction of radially oriented diaphragm fibers. The inspiratory muscles remain highly resistant to fatigue in patients with COPD, and the ultimate development of ventilatory failure is associated with insufficient central drive. Sleep is associated with reduced respiratory drive and impairments of lung and chest wall function, which are exaggerated in COPD patients. Profound hypoxemia and hypercapnia can occur in rapid eye movement sleep and contribute to the development of cor pulmonale. Inspiratory muscles adapt to chronic loading with an increased proportion of slow, fatigue-resistant fiber types, increased oxidative capacity, and reduced fiber cross-sectional area, but the capacity of the diaphragm to increase ventilation in exercise is compromised in COPD. In COPD, neural drive to the diaphragm increases to near maximal levels in exercise, but it does not develop peripheral muscle fatigue. The improvement in exercise capacity and dyspnea following lung volume reduction surgery is associated with a substantial reduction in neural drive to the inspiratory muscles.

INSPIRATIonAL--INSPIRAtory muscle training in amyotrophic lateral sclerosis.

Respiratory impairment, due to respiratory muscle weakness, is a major cause of morbidity and mortality in patients with amyotrophic lateral sclerosis/motor neuron disease (ALS/MND). Threshold loading may strengthen the inspiratory muscles and thereby improve patient prognosis. A phase II, double-blind, randomized-controlled trial was undertaken to determine whether a 12-week inspiratory muscle training programme attenuated the decline in respiratory function and inspiratory muscle strength in patients with ALS/MND. Nine patients were randomized to inspiratory muscle training and 10 to sham training. Primary endpoints were respiratory function (forced vital capacity, vital capacity), lung volumes and inspiratory muscle strength. Patients were assessed before, during and immediately after a 12-week training period, and at eight weeks follow-up. While improvements in inspiratory muscle strength were observed in both treatment arms, there was a non-significant increase in maximum inspiratory pressure of 6.1% in the experimental group compared to controls (standard error of mean, 6.93%; 95% confidence interval -8.58 -20.79; p=0.39). The gains in inspiratory muscle strength were partially reversed during a period of training cessation. In conclusion, inspiratory muscle training may potentially strengthen the inspiratory muscles and slow the decline in respiratory function in patients with ALS/MND.

Panic attacks and perception of inspiratory resistive loads in chronic obstructive pulmonary disease.

RATIONALE: Panic attacks are common in chronic obstructive pulmonary disease (COPD), and the prevalence of panic disorder is at least 10 times higher than in the general population. In the current study, we examined resistive load perception in patients with COPD with and without panic attacks. OBJECTIVES: We tested competing hypotheses, based on conflicting results of earlier studies, that those patients with COPD with panic attacks or panic disorder would show either heightened or blunted perception of dyspnea as the magnitude of inspiratory resistive loads increased. METHODS: We compared 20 patients with COPD with panic attacks or panic disorder, 20 patients without panic, and 20 healthy, age-matched subjects using an inspiratory resistive load-testing protocol. MEASUREMENTS AND MAIN RESULTS: We administered a diagnostic interview for panic attacks and panic disorder. We measured perceived dyspnea in response to increasing inspiratory resistive loads (modified Borg scale) and several respiratory variables. Dyspnea ratings increased linearly for all groups as the size of resistive loads increased. No significant differences were found between groups on the respiratory variables. Patients with COPD with panic attacks or panic disorder rated their level of dyspnea significantly higher than did other subjects. CONCLUSIONS: Patients with COPD with panic attacks showed heightened sensitivity to inspiratory loads. The result reinforces the influence of psychological factors on symptom perception in this disease.