How to eat, drink and speak on non-invasive ventilation.

We report our observations on six individuals with non-bulbar neuromuscular disorders using non-invasive ventilation (NIV), who were able to maintain adequate hydration and nutrition orally despite being ventilator-dependant. All had severe respiratory muscle weakness, with a vital capacity less than 500 mL and cough peak flow rate less than 250 L/min. Their median (range) age was 49 (23-64) years; they had been on NIV for 8 (2-24) years. We compared them with an age- and sex-matched normal control. Individuals with neuromuscular disorders needed to chew each mouthful of food significantly more times (median 44, range 18-120 chews) than normal controls (median 15, range 10-20 chews). They took longer to completely swallow a mouthful of food (median 37, range 24-100 s) compared to normal controls (median 14.5, range 10-21 s). Multiple swallows for each mouthful were seen in all neuromuscular individuals, but in only one normal control. Two individuals coughed after swallowing; both these subjects were clinically stable at the time of the study. The median number of NIV breaths associated with chest expansion for each mouthful was 11 (range 5-49). All subjects blocked some NIV breaths whilst eating. Before swallowing, they always waited until the expiratory phase of the NIV breath was complete; no post-swallow expiration was seen, whereas normal subjects invariably exhibited post-swallow expiration. All individuals were able to block several ventilator breaths whilst swallowing un-thickened liquids. The median (range) number of words between breaths was 5 (4-7) for the neuromuscular individuals on NIV, significantly fewer than 11 (8-13) for the matched controls. Eating, drinking and speaking are possible whilst on NIV. Use of cough-assist after eating is recommended, given the likelihood of silent aspiration.

A retrospective cohort study of idiopathic diaphragmatic palsy: a diagnostic triad, natural history and prognosis.

BACKGROUND: Isolated diaphragmatic palsy in the absence of progressive neuromuscular disease is uncommon. It poses diagnostic challenges and limited data are available regarding prognosis. We present retrospective cohort data from two large teaching hospitals in the United Kingdom. METHOD: 60 patients who were assessed either as inpatients or outpatients were included in this study. Patients with progressive neuromuscular disease were excluded. Clinical presentation, tests of respiratory muscle function (sitting/supine vital capacity, maximal expiratory pressure (MEP), maximal inspiratory pressure (MIP) and sniff nasal inspiratory pressure (SNIP)) and outcomes were recorded. RESULTS: For patients with diaphragmatic palsy, mean±sd seated and supine vital capacity pre-noninvasive ventilation (NIV) were reduced at 1.7±1.2 L and 1.1±0.9 L, respectively, with a mean±sd postural fall in vital capacity of 42±0.16%. The mean MEP/MIP and MEP/SNIP ratios for diaphragmatic palsy were 3 and 3.5, respectively. After a year of treatment with NIV, mean±sd upright and supine vital capacity had increased to 2.1±0.9 L and 1.8±1 L, respectively, and the mean±sd fall in vital capacity from sitting to supine reduced to 29±0.17%. MEP/MIP and MEP/SNIP ratios reduced to 2.6 and 2.9, respectively, from the pre-NIV values. The values of postural fall in vital capacity correlated (p<0.05) with MEP/MIP and MEP/SNIP ratio (r2=0.86 and r2=0.7, respectively). CONCLUSION: Tests of respiratory muscle strength are valuable in the diagnostic workup of patients with unexplained dyspnoea. A triad of 1) orthopnoea, with 2) normal lung imaging and 3) MEP/MIP and/or MEP/SNIP ratio ≥2.7 points towards isolated diaphragmatic palsy. This needs to be confirmed by prospective studies.

Long-Term Survival on Noninvasive Ventilation in Adults With Thoracic Scoliosis.

BACKGROUND: Subjects with thoracic scoliosis were an important group in early studies of noninvasive ventilation (NIV). The aim of this study was to describe current rates of initiation of NIV and survival after initiation in this population. METHODS: This study included patients identified as having thoracic scoliosis and established between 1993 and 2018 on home NIV. Patients with scoliosis secondary to neuromuscular disease (other than poliomyelitis) were excluded. Survival rates were calculated for various time intervals up to 25 y. RESULTS: A total of 53 subjects with thoracic scoliosis were successfully established on NIV. [Formula: see text] levels prior to starting NIV were 55 ± 23 mm Hg. FVC was 0.5 ± 0.1 L, 18.5 ± 9% of predicted, with a Cobb angle of 101 ± 3.5 degrees. The 5-, 10-, 15-, 20-, and 25-y survival rates were 96%, 88%, 61%, 46%, and 39%, respectively. At the time of death, subjects had been on home NIV for 9.2 ± 5.1 y and were 75.5 ± 9.2 y old. There was no significant correlation between mortality and age at time of commencing home NIV, initial arterial blood gas results, FVC, or Cobb angle. There was no significant difference in survival between those with and without poliomyelitis. In 8 of 10 of the most recent years of this survey, subjects with scoliosis have been commenced on home NIV. CONCLUSIONS: Small numbers of subjects with scoliosis continued to present with respiratory failure. Once established on home NIV, around 40% survived ≥ 25 y. Long-term care will be needed for many years to come for this patient population.

Correction of Paradoxical Ribcage Motion in Scoliosis by Noninvasive Ventilation.

STUDY DESIGN: Observational study of ribcage motion in scoliosis. OBJECTIVE: To see whether noninvasive ventilation corrected paradoxical inward motion of the ribs during inspiration. SUMMARY OF BACKGROUND DATA: Paradoxical inward motion of the ribs is observed after rib fractures, low cervical cord injury, and in chronic obstructive pulmonary disease. It is not well recognized in scoliosis and the mechanism in this group has not been studied. METHODS: Linearized magnetometers were used to measure the diameter of the ribcage. Changes in diameter during tidal breathing were recorded during spontaneous ventilation and noninvasive ventilation in 10 subjects with idiopathic or congenital thoracic scoliosis. RESULTS: During spontaneous breathing, the median change in ribcage diameter during inspiration was -1.5 (range -2.3 to -0.8) cm. The median change in ribcage diameter during noninvasive ventilation was +0.5 (range -1.1 to +1.2) cm. Noninvasive ventilation improved paradoxical motion in all subjects, completely correcting it in six. CONCLUSION: Paradoxical inward motion of the ribcage is seen in some subjects with severe scoliosis. This abnormal motion is improved or abolished by noninvasive ventilation. Since noninvasive ventilation takes over the work of breathing from the respiratory muscles, we suggest that inspiratory muscle contraction causes distortion of part of the ribcage in scoliosis, probably because of the abnormal orientation of diaphragmatic muscle fibers. LEVEL OF EVIDENCE: 2.

Characterization and Use of a Fiber Optic Sensor Based on PAH/SiO2 Film for Humidity Sensing in Ventilator Care Equipment.

OBJECTIVE: To develop a compact probe that can be used to monitor humidity in ventilator care equipment. A mesoporous film of alternate layers of Poly(allylamine hydrochloride) (PAH) and silica (SiO2) nanoparticles (bilayers), deposited onto an optical fibre was used. The sensing film behaves as a Fabry-Perot cavity of low-finesse where the absorption of water vapour changes the optical thickness and produces a change in reflection proportional to humidity. METHODS: The mesoporous film was deposited upon the cleaved tip of an optical fibre using the layer-by-layer method. The sensor was calibrated in a bench model against a commercially available capacitive sensor. The sensitivity and response time were assessed in the range from 5 % relative humidity (RH) to 95%RH for different numbers of bilayers up to a maximum of nine. RESULTS: The sensitivity increases with the number of bilayers deposited; sensitivity of 2.28 mV/%RH was obtained for nine bilayers. The time constant of the response was 1.13 s ± 0.30 s which is faster than the commercial device (measured as 158 s). After calibration, the optical fibre humidity sensor was utilised in a bench top study employing a mechanical ventilator. The fast response time enabled changes in humidity in individual breaths to be resolved. CONCLUSION: Optical fibre sensors have the potential to be used to monitor breath to breath humidity during ventilator care. SIGNIFICANCE: Control of humidity is an essential part of critical respiratory care and the developed sensor provides a sensitive, compact and fast method of humidity monitoring.

Using venous blood gas analysis in the assessment of COPD exacerbations: a prospective cohort study.

INTRODUCTION: Identifying acute hypercapnic respiratory failure is crucial in the initial management of acute exacerbations of COPD. Guidelines recommend obtaining arterial blood samples but these are more difficult to obtain than venous. We assessed whether blood gas values derived from venous blood could replace arterial at initial assessment. METHODS: Patients requiring hospital treatment for an exacerbation of COPD had paired arterial and venous samples taken. Bland-Altman analyses were performed to assess agreement between arterial and venous pH, CO2 and HCO3-. The relationship between SpO2 and SaO2 was assessed. The number of attempts and pain scores for each sample were measured. RESULTS: 234 patients were studied. There was good agreement between arterial and venous measures of pH and HC)3- (mean difference 0.03 and -0.04, limits of agreement -0.05 to 0.11 and -2.90 to 2.82, respectively), and between SaO2 and SpO2 (in patients with an SpO2 of >80%). Arterial sampling required more attempts and was more painful than venous (mean pain score 4 (IQR 2-5) and 1 (IQR 0-2), respectively, p<0.001). CONCLUSIONS: Arterial sampling is more difficult and more painful than venous sampling. There is good agreement between pH and HCO3- values derived from venous and arterial blood, and between pulse oximetry and arterial blood gas oxygen saturations. These agreements could allow the initial assessment of COPD exacerbations to be based on venous blood gas analysis and pulse oximetry, simplifying the care pathway and improving the patient experience.

Intrapleural use of tissue plasminogen activator and DNase in pleural infection.

BACKGROUND: More than 30% of patients with pleural infection either die or require surgery. Drainage of infected fluid is key to successful treatment, but intrapleural fibrinolytic therapy did not improve outcomes in an earlier, large, randomized trial. METHODS: We conducted a blinded, 2-by-2 factorial trial in which 210 patients with pleural infection were randomly assigned to receive one of four study treatments for 3 days: double placebo, intrapleural tissue plasminogen activator (t-PA) and DNase, t-PA and placebo, or DNase and placebo. The primary outcome was the change in pleural opacity, measured as the percentage of the hemithorax occupied by effusion, on chest radiography on day 7 as compared with day 1. Secondary outcomes included referral for surgery, duration of hospital stay, and adverse events. RESULTS: The mean (±SD) change in pleural opacity was greater in the t-PA-DNase group than in the placebo group (-29.5±23.3% vs. -17.2±19.6%; difference, -7.9%; 95% confidence interval [CI], -13.4 to -2.4; P=0.005); the change observed with t-PA alone and with DNase alone (-17.2±24.3 and -14.7±16.4%, respectively) was not significantly different from that observed with placebo. The frequency of surgical referral at 3 months was lower in the t-PA-DNase group than in the placebo group (2 of 48 patients [4%] vs. 8 of 51 patients [16%]; odds ratio for surgical referral, 0.17; 95% CI, 0.03 to 0.87; P=0.03) but was greater in the DNase group (18 of 46 patients [39%]) than in the placebo group (odds ratio, 3.56; 95% CI, 1.30 to 9.75; P=0.01). Combined t-PA-DNase therapy was associated with a reduction in the hospital stay, as compared with placebo (difference, -6.7 days; 95% CI, -12.0 to -1.9; P=0.006); the hospital stay with either agent alone was not significantly different from that with placebo. The frequency of adverse events did not differ significantly among the groups. CONCLUSIONS: Intrapleural t-PA-DNase therapy improved fluid drainage in patients with pleural infection and reduced the frequency of surgical referral and the duration of the hospital stay. Treatment with DNase alone or t-PA alone was ineffective. (Funded by an unrestricted educational grant to the University of Oxford from Roche UK and by others; Current Controlled Trials number, ISRCTN57454527.).

The prevalence of nocturnal hypoxemia in advanced cancer.

Nocturnal hypoxemia is associated with excessive daytime sleepiness in patients with chronic respiratory disease. This relationship has not been explored in patients with cancer. This study examined the prevalence of nocturnal hypoxemia in patients admitted to a specialist palliative care unit, and explored relationships with demographic and physiological parameters, opioid or other sedative drug use, and daytime sleepiness, fatigue, and quality of life. Demographic details, diagnosis, performance status, body mass index, opioid or other sedative drug use, hemoglobin, spirometry, and sniff nasal inspiratory pressures were obtained, along with Epworth Sleepiness Scale, Multidimensional Fatigue Inventory, and Short Form-36 health questionnaire scores. An oximeter recorded resting daytime oxygen saturation (SaO2); overnight SaO2 was recorded for a minimum of five hours. Nocturnal hypoxemia was defined as SaO2<90% for >or=2% of the monitored nighttime. Of 100 patients, 35 had nocturnal hypoxemia. These were more likely to have lung disease (P<0.05), a lower forced expiratory volume in one second % predicted (P=0.01), lower daytime SaO2 (P=0.01) and higher levels of mental fatigue (difficulty concentrating) (P=0.02), compared to those without nocturnal hypoxemia. Both groups exhibited abnormal levels of daytime sleepiness. Nocturnal hypoxemia is common in this group of patients and may contribute to mental fatigue (difficulty concentrating).

Weaning from ventilation: does a care bundle approach work?

There has been renewed interest in weaning from mechanical ventilation in critical care since the publication of the Modernisation Agency paper in 2002. There have been many papers reporting ways of improving the weaning process but these are specific to single elements and neglect the contextual issues that influence the weaning process. Care bundles have been introduced nationally to standardise patient care and improve patient outcome. Examples in critical care are the ventilator care bundle and sepsis care bundle. However, since care bundles have become linked with targets and part of the 10 High Impact Changes there is a tendency to want to call everything a care bundle. A care bundle is a small but critical set of processes that when implemented together improve outcome. One critical care network has written a weaning care bundle. This is an example of a service improvement initiative the aim of which was to improve weaning from mechanical ventilation. This paper reviews this approach and presents results from a pilot in one teaching hospital.

Enhanced delivery of nebulised salbutamol during non-invasive ventilation.

Non-invasive ventilation (NIV) is used to treat acute respiratory failure. Nebulised drugs can be delivered concurrently with NIV or during breaks from ventilatory support. We hypothesised that the amount of nebulised salbutamol inhaled when delivered via bi-level ventilation would be no different to the amount available directly from the same nebuliser. A standard bi-level ventilation circuit was attached to a lung model simulating adult respiration. Drug delivery was compared when salbutamol (5 mg) was nebulised at different positions in the circuit and separately, with no ventilator. The amount of salbutamol contained in various particle size fractions was also determined. Nebuliser position within the NIV circuit was critically important for drug delivery. Optimal delivery of salbutamol occurred with the expiration port between the facemask and nebuliser (647+/-67 micro g). This was significantly better than nebulisation without the ventilator (424+/-61 micro g; P < 0.01). Delivery when the nebuliser was positioned between the facemask and expiration port was 544+/-85 micro g. The amount of salbutamol contained in particles < 5 micro m was significantly increased when the nebuliser was used in conjunction with bi-level ventilation (576+/-60 micro g vs 300+/-43 micro g, P < 0.001). We conclude that nebulised bronchodilator therapy, using a Cirrus jet nebuliser, during bi-level ventilation increases respirable particles likely to be inhaled when the nebuliser is optimally positioned within the circuit.

Management of respiration in MND/ALS patients: an evidence based review.

This systematic review comprises an objective appraisal of the evidence in regard to the management of respiration in patients with motor neuron disease (MND/ALS). Studies were identified through computerised searches of 32 databases. Internet searches of websites of drug companies and MND/ALS research web sites, 'snow balling' and hand searches were also employed to locate any unpublished study or other 'grey literature' on respiration and MND/ALS. Since management of MND/ALS involves a number of health professionals and care workers, searches were made across multiple disciplines. No time frame was imposed on the search in order to increase the probability of identifying all relevant studies, although there was a final limit of March 2005. Recommendations for patient and carer-based guidelines for the clinical management of respiration for MND/ALS patients are suggested on the basis of qualitative analyses of the available evidence. However, these recommendations are based on current evidence of best practice, which largely comprises observational research and clinical opinion. There is a clear need for further evidence, in particular randomised and non-randomised controlled trials on the effects of non-invasive ventilation and additional larger scale cohort studies on the issues of initial assessment of respiratory symptoms, and management and timing of interventions.