Non-invasive ventilation in chronic obstructive pulmonary disease: management of acute type 2 respiratory failure

A pragmatic, open-label, multi-center, randomized controlled clinical trial on the rotational use of interfaces vs standard of care in patients treated with noninvasive positive pressure ventilation for acute hypercapnic respiratory failure: the ROTAtional-USE of interface STUDY (ROTA-USE STUDY)

BACKGROUND

In the last decades, noninvasive ventilation (NIV) has been increasingly used to support patients with hypercapnic and hypoxemic acute respiratory failure. Pressure ulcers are a frequently observed NIV-related adverse effect, directly related to interface type and exposure time. Switching to a different interface has been proposed as a solution to improve patient comfort. However, large studies investigating the benefit of this strategy are not available. Thus, the aim of the ROTAtional-USE of interface STUDY (ROTA-USE STUDY) is to investigate whether a protocolized rotational use of interfaces during NIV is effective in reducing the incidence of pressure ulcers.

METHODS

The ROTA-USE STUDY is a pragmatic, parallel arm, open-label, multicenter, spontaneous, non-profit, randomized controlled trial requiring non-significant risk medical devices, with the aim to determine whether a rotational strategy of NIV interfaces is associated with a lower incidence of pressure ulcers compared to the standard of care. In the intervention group, NIV mask will be randomly chosen and rotated every 6 h. In the control group, mask will be chosen according to the standard of care of the participating centers and changed in case of discomfort or in the presence of new pressure sores. In both groups, the skin underneath the mask will be inspected every 12 h for any possible damage by blinded assessors. The primary outcome is the proportion of patients developing new pressure sores at 36 h from randomization. The secondary outcomes are (i) onset of pressure sores measured at different time points, i.e., 12, 24, 36, 48, 60, 72, 84, and 96 h; (ii) number and stage of pressure sores and comfort measured at 12, 24, 36, 48, 60, 72, 84, and 96 h; and (iii) the economic impact of the protocolized rotational use of interfaces. A sample size of 239 subjects per group (intervention and control) is estimated to detect a 10% absolute difference in the proportion of patients developing pressure sores at 36 h.

DISCUSSION

The development of pressure ulcers is a common side effect of NIV that negatively affects the patients' comfort and tolerance, often leading to NIV failure and adverse outcomes. The ROTA-USE STUDY will determine whether a protocolized rotational approach can reduce the incidence, number, and severity of pressure ulcers in NIV-treated patients.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05513508. Registered on August 24, 2022.

Acceptance and adherence to non-invasive positive pressure ventilation in people with chronic obstructive pulmonary disease: a grounded theory study

Introduction

Non-Invasive Positive Pressure Ventilation (NPPV) is an established treatment for people with Chronic Obstructive Pulmonary Disease (COPD), but it is often improperly used or rejected. The patterns of acceptance and adherence to NPPV, conceiving constraints, and strengths related to its adaptation have not been explored from a qualitative perspective yet.

Objectives

This study aims to qualitatively explore patterns of adaptation to NPPV in people affected by COPD and to identify the core characteristics and the specific adaptive challenges during the adaptation process.

Methods

Forty-two people with moderate or severe COPD were recruited and 336 unstructured interviews were conducted. A Constructivist Grounded Theory was used to gather and analyze data: the transcriptions were mutually gathered in open, selective, and theoretical phases, with open, selective, and theoretical coding, respectively.

Results

The analysis resulted in a non-linear and dynamic process, characterized by three phases: deciding, trying NPPV, and using NPPV. The patterns revealed that positive and negative NPPV experiences, together with beliefs, emotions, stressful mental states, and behaviors result in different acceptance and adherence rates.

Discussions

These findings may be helpful to implement new care strategies to promote acceptance and adherence to NPPV.

Treatment of COVID-19 Acute Respiratory Distress Syndrome With a Tabletop Noninvasive Ventilation Device in a Respiratory Intermediate Care Unit

Objective

To study the outcomes of noninvasive ventilation (NIV) administered through a tabletop device for coronavirus disease 2019 acute respiratory distress syndrome in the respiratory intermediate care unit (RIMCU) at a tertiary care hospital in India.

Patients and Methods

We retrospectively studied a cohort of hospitalized patients deteriorating despite low-flow oxygen support who received protocolized management with positive airway pressure using a tabletop NIV device in the RIMCU as a step-up rescue therapy from July 30, 2020 to November 14, 2020. Treatment was commenced on the continuous positive airway pressure mode up to a pressure of 10 cm of H2O, and if required, inspiratory pressures were added using the bilevel positive air pressure mode. Success was defined as weaning from NIV and stepping down to the ward, and failure was defined as escalation to the intensive care unit, the need for intubation, or death.

Results

In total, 246 patients were treated in the RIMCU during the study period. Of these, 168 received respiratory support via a tabletop NIV device as a step-up rescue therapy. Their mean age was 54 years, and 83% were men. Diabetes mellitus (78%) and hypertension (44%) were the commonest comorbidities. Treatment was successful with tabletop NIV in 77% (129/168) of the patients; of them, 41% (69/168) received treatment with continuous positive airway pressure alone and 36% (60/168) received additional increased inspiratory pressure via the bilevel positive air pressure mode.

Conclusion

Respiratory support using the tabletop NIV device was an effective and economical treatment for coronavirus disease 2019 acute respiratory distress syndrome. Further studies are required to assess the appropriate time of initiation for maximal benefits and judicious utilization of resources.

Predictors of success and failure of non-invasive ventilation use in type-2 respiratory failure

BACKGROUND

Non-invasive ventilation is widely used now a days in patients with hypercapnic respiratory failure. Non-invasive ventilation can be used in Intensive Care Unit setting and wards provided trained staff is there to monitor.

METHODS

This was a prospective observational study of 100 adult patients who were admitted with hypercapnic respiratory failure. Demographic information such as Age, Sex were recorded. Clinical parameters like Respiratory Rate, Heart Rate, Oxygen saturation and Arterial Blood Gas variables like pH, PaCO₂, HCO₃ were measured at the time of admission and at 1st hour, 4 hours and 24 hours after start of non-invasive ventilation. Outcome was recorded as success and failure with Non invasive ventilation.

RESULTS

Out of 100 patients, 76 (76%) managed successfully with non-invasive ventilation and 24 patients (24%) needed intubation and invasive mechanical ventilation in this study. Majority of patients (76%) were with clinical diagnosis of Chronic Obstructive Pulmonary Disease. Respiratory Rate and Heart Rate were significantly lower and showed significant improvement at 1st hour, 4 hours and 24 hours in patients who successfully improved with Non invasive ventilation. Oxygen saturation was found to be significantly higher among patients successfully managed with Non invasive ventilation (84.35 ± 8.55 vs 76.87 ± 7.33) as compared to patients who required intubation. pH was found to be significantly higher (7.28 ± 0.06 vs 7.23 ± 0.05) in patients showing good response to Non invasive ventilation and improvement in pH at 1st hour, 4 hours and 24 hours was observed in patients successfully managed with Non invasive ventilation. PaCO₂ level was found to be significantly lower and significant improvement in PaCO₂ at 1st hour, 4 hours and 24 hours was seen in patients with Non invasive ventilation success.

CONCLUSION

Improvement in clinical parameters like respiratory rate, heart rate, Oxygen saturation and improvement in ABG variables like pH, PaCO2 after 1st and 4 hours of start of Non invasive ventilation and maintaining the improvement at 24 hours are predictors of success of non-invasive ventilation in hypercapnic patients.

Protocolised non-invasive compared with invasive weaning from mechanical ventilation for adults in intensive care: the Breathe RCT

BACKGROUND

Invasive mechanical ventilation (IMV) is a life-saving intervention. Following resolution of the condition that necessitated IMV, a spontaneous breathing trial (SBT) is used to determine patient readiness for IMV discontinuation. In patients who fail one or more SBTs, there is uncertainty as to the optimum management strategy.

OBJECTIVE

To evaluate the clinical effectiveness and cost-effectiveness of using non-invasive ventilation (NIV) as an intermediate step in the protocolised weaning of patients from IMV.

DESIGN

Pragmatic, open-label, parallel-group randomised controlled trial, with cost-effectiveness analysis.

SETTING

A total of 51 critical care units across the UK.

PARTICIPANTS

Adult intensive care patients who had received IMV for at least 48 hours, who were categorised as ready to wean from ventilation, and who failed a SBT.

INTERVENTIONS

Control group (invasive weaning): patients continued to receive IMV with daily SBTs. A weaning protocol was used to wean pressure support based on the patient's condition. Intervention group (non-invasive weaning): patients were extubated to NIV. A weaning protocol was used to wean inspiratory positive airway pressure, based on the patient's condition.

MAIN OUTCOME MEASURES

The primary outcome measure was time to liberation from ventilation. Secondary outcome measures included mortality, duration of IMV, proportion of patients receiving antibiotics for a presumed respiratory infection and health-related quality of life.

RESULTS

A total of 364 patients (invasive weaning, n = 182; non-invasive weaning, n = 182) were randomised. Groups were well matched at baseline. There was no difference between the invasive weaning and non-invasive weaning groups in median time to liberation from ventilation {invasive weaning 108 hours [interquartile range (IQR) 57-351 hours] vs. non-invasive weaning 104.3 hours [IQR 34.5-297 hours]; hazard ratio 1.1, 95% confidence interval [CI] 0.89 to 1.39; p = 0.352}. There was also no difference in mortality between groups at any time point. Patients in the non-invasive weaning group had fewer IMV days [invasive weaning 4 days (IQR 2-11 days) vs. non-invasive weaning 1 day (IQR 0-7 days); adjusted mean difference -3.1 days, 95% CI -5.75 to -0.51 days]. In addition, fewer non-invasive weaning patients required antibiotics for a respiratory infection [odds ratio (OR) 0.60, 95% CI 0.41 to 1.00; p = 0.048]. A higher proportion of non-invasive weaning patients required reintubation than those in the invasive weaning group (OR 2.00, 95% CI 1.27 to 3.24). The within-trial economic evaluation showed that NIV was associated with a lower net cost and a higher net effect, and was dominant in health economic terms. The probability that NIV was cost-effective was estimated at 0.58 at a cost-effectiveness threshold of £20,000 per quality-adjusted life-year.

CONCLUSIONS

A protocolised non-invasive weaning strategy did not reduce time to liberation from ventilation. However, patients who underwent non-invasive weaning had fewer days requiring IMV and required fewer antibiotics for respiratory infections.

FUTURE WORK

In patients who fail a SBT, which factors predict an adverse outcome (reintubation, tracheostomy, death) if extubated and weaned using NIV?

TRIAL REGISTRATION

Current Controlled Trials ISRCTN15635197.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 23, No. 48. See the NIHR Journals Library website for further project information.

Arterial and transcutaneous variability and agreement between multiple successive measurements of carbon dioxide in patients with chronic obstructive lung disease

PURPOSE

This study evaluates agreement between carbon dioxide measured arterial (PaCO₂) and transcutaneous (PtcCO₂) over time, by repeated successive measures, taking into consideration the inherent variability of arterial measurements.

METHODS AND RESULTS

11 patients receiving LTOT, with severe to very severe COPD in a stable phase were studied. Repeated arterial blood samples were drawn and PtcCO₂ measured simultaneously at the ear lobe. Bland-Altman analysis was used to evaluate 95 % limits of agreement (LoA). 194 paired samples were analysed. Following correction for bias, the difference between PaCO₂ and PtCO₂ during dynamic conditions was 0.02 kPa and LoA 0.94 to -0.90 kPa while 29 % of PtCO₂ measurements were outside the range of variability for arterial measurements.

CONCLUSION

PtcCO₂ corrected for intra-patient bias provide reasonable description of PaCO₂ values within but not outside steady state conditions. Our results suggest that PtcCO₂ is a valuable method for monitoring in chronic rather than acute conditions when bias can be removed.

Arterio-VENouS Intra Subject agreement for blood gases within intensive care: The AVENSIS study

Background

In critically ill patients, who require multiple blood gas assessments, agreement between arterial and venous blood gas values for pH and partial pressure of carbon dioxide, is not clear. Good agreement would mean that venous values could be used to assess ventilation and metabolic status of patients in intensive care unit.

Methods

All adult patients admitted to Alfred intensive care unit, Melbourne, from February 2013 to January 2014, who were likely to have arterial and central venous lines for three days, were enrolled. Patients on extra-corporeal life support and pregnant women were excluded. After enrolment, near simultaneous arterial and central venous sampling and analysis were performed at least once per nursing shift till the lines were removed or the patient died. Bland-Altman analysis for repeated measures was performed to assess the agreement between arterio-venous pH and partial pressure of carbon dioxide.

Results

A total of 394 paired blood gas analyses were performed from 59 participants. The median (IQR) number of samples per patient was 6 (5-9) with the median (IQR) sampling interval 9.4 (5.2-18.5) h. The mean bias for pH was  + 0.036 with 95% limits of agreement ranging from - 0.005 to + 0.078. For partial pressure of carbon dioxide, the values were -2.58 and -10.43 to + 5.27 mmHg, respectively.

Conclusions

The arterio-venous agreement for pH in intensive care unit patients appears to be acceptable. However, the agreement for partial pressure of carbon dioxide was poor.

A comparison of three strategies for withdrawal of noninvasive ventilation in chronic obstructive pulmonary disease with acute respiratory failure: Randomized trial

Background:

The optimal strategy for the withdrawal of noninvasive ventilation (NIV) remains unknown. This study was planned to compare three different strategies for the withdrawal of NIV among patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD) with hypercapnic respiratory failure (HcRF).

Materials and Methods:

Patients with AECOPD with HcRF who improved on NIV were randomized into three groups – immediate withdrawal (Group A), stepwise reduction of pressure support (Group B), and stepwise reduction of duration (Group C) of NIV. The probability of successful withdrawal was compared among the groups.

Results:

This study included 90 patients (males – 86.6%) with a mean (±standard deviation [SD]) age of 59.9 ± 8.3 years. The mean (±SD) pH and PaCO₂ at admission were 7.23 ± 0.04 and 84.4 ± 12.0 mm Hg, respectively. The duration of NIV received before randomization was 31.6 ± 9.2 h with maximum inspiratory positive airway pressure and expiratory positive airway pressure of 17.6 ± 2.7 cm H₂O and 7.4 ± 1.4 cm H₂O, respectively. NIV was successfully withdrawn in 23/30 (76.6%) in Group A, 27/30 (90%) in Group B, and 26/30 (86.6%) in Group C (P = 0.31). The total duration of NIV use and length of hospital stay was lower in Group A and B as compared to Group C (P = 0.001).

Conclusions:

Immediate withdrawal of the NIV after recovery of respiratory failure among patients with exacerbation of COPD is feasible. Immediate withdrawal did not increase the risk of weaning failure from the NIV.

Development of non-invasive ventilation treatment practice for patients with chronic obstructive pulmonary disease:Results from a participatory research project

Objectives

Non-invasive ventilation treatment for patients with acute exacerbation of chronic obstructive pulmonary disease is well documented. Communication with patients during treatment is inhibited because of the mask, the noise from the machine and patient distress. Assessing life expectancy and identifying end-stage chronic obstructive pulmonary disease posed difficulties and caused doubts concerning initiation and continuation of non-invasive ventilation as life-sustaining treatment. Health professionals expressed a need for knowledge of patients' perspectives and attitude towards non-invasive ventilation.

Methods

The study adheres to principles of Critical psychological practice research. Data on patients' and health professionals' perspectives were obtained from observations from the ward and semi-structured interviews with 16 patients. A group of health professionals was set up to form a co-researcher group. The co-researcher group described and analysed treatment practice at the department, drawing on research literature, results from observations and patients' interviews.

Results

Interviews revealed that 15 patients evaluated treatment with non-invasive ventilation positively, although 13 had experienced fear and 14 discomfort during treatment. The co-researcher group described health professionals' perspectives and analysed treatment practice based on data from patients' perspectives developing new management strategies in clinical practice with non-invasive ventilation.

Conclusion

The participatory approach enabled continuous and complementary development of knowledge and treatment practice. The investigation of patient perspectives was particularly productive in qualifying cooperation among health professionals. The study resulted in preparing, and implementing, new clinical strategies.

Effect of time and day of admission on hospital care quality for patients with chronic obstructive pulmonary disease exacerbation in England and Wales: single cohort study

OBJECTIVE

To evaluate if observed increased weekend mortality was associated with poorer quality of care for patients admitted to hospital with chronic obstructive pulmonary disease (COPD) exacerbation.

DESIGN

Prospective case ascertainment cohort study.

SETTING

199 acute hospitals in England and Wales, UK.

PARTICIPANTS

Consecutive COPD admissions, excluding subsequent readmissions, from 1 February to 30 April 2014 of whom 13 414 cases were entered into the study.

MAIN OUTCOMES

Process of care mapped to the National Institute for Health and Care Excellence clinical quality standards, access to specialist respiratory teams and facilities, mortality and length of stay, related to time and day of the week of admission.

RESULTS

Mortality was higher for weekend admissions (unadjusted OR 1.20, 95% CI 1.00 to 1.43), and for case-mix adjusted weekend mortality when calculated for admissions Friday morning through to Monday night (adjusted OR 1.19, 95% CI 1.00 to 1.43). Median time to death was 6 days. Some clinical processes were poorer on Mondays and during normal working hours but not weekends or out of hours. Specialist respiratory care was less available and less prompt for Friday and Saturday admissions. Admission to a specialist ward or high dependency unit was less likely on a Saturday or Sunday.

CONCLUSIONS

Increased mortality observed in weekend admissions is not easily explained by deficiencies in early clinical guideline care. Further study of out-of-hospital factors, specialty care and deaths later in the admission are required if effective interventions are to be made to reduce variation by day of the week of admission.

IL-8 predicts early mortality in patients with acute hypercapnic respiratory failure treated with noninvasive positive pressure ventilation

Background

Patients with Acute Hypercapnic Respiratory Failure (AHRF) who are unresponsive to appropriate medical treatment, are often treated with Noninvasive Positive Pressure Ventilation (NPPV). Clinical predictors of the outcome of this treatment are scarce. Therefore, we evaluated the role of the biomarkers IL-8 and GDF-15 in predicting 28-day mortality in patients with AHRF who receive treatment with NPPV.

Methods

The study population were 46 patients treated with NPPV for AHRF. Clinical and background data was registered and blood samples taken for analysis of inflammatory biomarkers. IL-8 and GDF-15 were selected for analysis, and related to risk of 28-day mortality (primary endpoint) using Cox proportional hazard models adjusted for gender, age and various clinical parameters.

Results

Of the 46 patients, there were 3 subgroup in regards to primary diagnosis: Acute Exacerbation of COPD (AECOPD, n = 34), Acute Heart Failure (AHF, n = 8) and Acute Exacerbation in Obesity Hypoventilation Syndrome (AEOHS, n = 4). There was significant difference in the basic characteristic of the subgroups, but not in the clinical parameters that were used in treatment decisions. 13 patients died within 28 days of admission (28%). The Hazard Ratio for 28-days mortality per 1-SD increment of IL-8 was 3.88 (95% CI 1.86–8.06, p < 0.001). When IL-8 values were divided into tertiles, the highest tertile had a significant association with 28 days mortality, HR 10.02 (95% CI 1.24–80.77, p for trend 0.03), compared with the lowest tertile. This correlation was maintained when the largest subgroup with AECOPD was analyzed. GDF-15 was correlated in the same way, but when put into the same model as IL-8, the significance disappeared.

Conclusion

IL-8 is a target to explore further as a predictor of 28 days mortality, in patients with AHRF treated with NPPV.

Case Report of a Pressure Ulcer Occurring Over the Nasal Bridge Due to a Non-Invasive Ventilation Facial Mask

Non-invasive ventilation (NIV) is used in patients with respiratory failure, sleep apnoea, and dyspnoea related to pulmonary oedema. NIV is provided through a facial mask. Many complications of NIV facial masks have been reported, including the breakdown of facial skin. We report a case of an elderly male admitted with multiple co-morbidities. The facial mask was applied continuously for NIV, without any relief or formal monitoring of the underlying skin. It resulted in a Grade II pressure ulcer. We discuss the possible mechanism and offer advice for prevention of such device-related pressure ulcers.

Pre-hospital non-invasive ventilation for acute respiratory failure: a systematic review and cost-effectiveness evaluation

BACKGROUND

Non-invasive ventilation (NIV), in the form of continuous positive airway pressure (CPAP) or bilevel inspiratory positive airway pressure (BiPAP), is used in hospital to treat patients with acute respiratory failure. Pre-hospital NIV may be more effective than in-hospital NIV but requires additional ambulance service resources.

OBJECTIVES

We aimed to determine the clinical effectiveness and cost-effectiveness of pre-hospital NIV compared with usual care for adults presenting to the emergency services with acute respiratory failure and to identify priorities for future research.

DATA SOURCES

Fourteen electronic databases and research registers (including MEDLINE In-Process & Other Non-Indexed Citations, MEDLINE, EMBASE, and Cumulative Index to Nursing and Allied Health Literature) were searched from inception to August 2013, supplemented by hand-searching reference lists and contacting experts in the field.

REVIEW METHODS

We included all randomised or quasi-randomised controlled trials of pre-hospital NIV in patients with acute respiratory failure. Methodological quality was assessed according to established criteria. An aggregate data network meta-analysis (NMA) of mortality and intubation was used to jointly estimate intervention effects relative to usual care. A NMA, using individual patient-level data (IPD) and aggregate data where IPD were not available, was carried out to assess whether or not covariates were treatment effect modifiers. A de novo economic model was developed to explore the costs and health outcomes when pre-hospital NIV (specifically CPAP provided by paramedics) and standard care (in-hospital NIV) were applied to a hypothetical cohort of patients with acute respiratory failure.

RESULTS

The literature searches identified 2284 citations. Of the 10 studies that met the inclusion criteria, eight were randomised controlled trials and two were quasi-randomised trials (six CPAP; four BiPAP; sample sizes 23-207 participants). IPD were available from seven trials (650 patients). The aggregate data NMA suggested that CPAP was the most effective treatment in terms of mortality (probability = 0.989) and intubation rate (probability = 0.639), and reduced both mortality [odds ratio (OR) 0.41, 95% credible interval (CrI) 0.20 to 0.77] and intubation rate (OR 0.32, 95% CrI 0.17 to 0.62) compared with standard care. The effect of BiPAP on mortality (OR 1.94, 95% CrI 0.65 to 6.14) and intubation rate (OR 0.40, 95% CrI 0.14 to 1.16) compared with standard care was uncertain. The combined IPD and aggregate data NMA suggested that sex was a statistically significant treatment effect modifier for mortality. The economic analysis showed that pre-hospital CPAP was more effective and more expensive than standard care, with an incremental cost-effectiveness ratio of £20,514 per quality-adjusted life-year (QALY) and a 49.5% probability of being cost-effective at the £20,000-per-QALY threshold. Variation in the incidence of eligible patients had a marked impact on cost-effectiveness and the expected value of sample information for a future randomised trial.

LIMITATIONS

The meta-analysis lacked power to detect potentially important differences in outcome (particularly for BiPAP), the intervention was not always compared with the best alternative care (in-hospital NIV) in the primary studies and findings may not be generalisable.

CONCLUSIONS

Pre-hospital CPAP can reduce mortality and intubation rates, but cost-effectiveness is uncertain and the value of further randomised evaluation depends on the incidence of suitable patients. A feasibility study is required to determine if a large pragmatic trial of clinical effectiveness and cost-effectiveness is appropriate.

STUDY REGISTRATION

The study is registered as PROSPERO CRD42012002933.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Pulmonary Protection Strategies in Cardiac Surgery: Are We Making Any Progress?

Pulmonary dysfunction is a common complication of cardiac surgery. The mechanisms involved in the development of pulmonary dysfunction are multifactorial and can be related to the activation of inflammatory and oxidative stress pathways. Clinical manifestation varies from mild atelectasis to severe respiratory failure. Managing pulmonary dysfunction postcardiac surgery is a multistep process that starts before surgery and continues during both the operative and postoperative phases. Different pulmonary protection strategies have evolved over the years; however, the wide acceptance and clinical application of such techniques remain hindered by the poor level of evidence or the sample size of the studies. A better understanding of available modalities and/or combinations can result in the development of customised strategies for the different cohorts of patients with the potential to hence maximise patients and institutes benefits.

Cost-effectiveness of Out-of-Hospital Continuous Positive Airway Pressure for Acute Respiratory Failure

STUDY OBJECTIVE

We determine the cost-effectiveness of out-of-hospital continuous positive airway pressure (CPAP) compared with standard care for adults presenting to emergency medical services with acute respiratory failure.

METHODS

We developed an economic model using a United Kingdom health care system perspective to compare the costs and health outcomes of out-of-hospital CPAP to standard care (inhospital noninvasive ventilation) when applied to a hypothetical cohort of patients with acute respiratory failure. The model assigned each patient a probability of intubation or death, depending on the patient's characteristics and whether he or she had out-of-hospital CPAP or standard care. The patients who survived accrued lifetime quality-adjusted life-years (QALYs) and health care costs according to their age and sex. Costs were accrued through intervention and hospital treatment costs, which depended on patient outcomes. All results were converted into US dollars, using the Organisation for Economic Co-operation and Development purchasing power parities rates.

RESULTS

Out-of-hospital CPAP was more effective than standard care but was also more expensive, with an incremental cost-effectiveness ratio of £20,514 per QALY ($29,720/QALY) and a 49.5% probability of being cost-effective at the £20,000 per QALY ($29,000/QALY) threshold. The probability of out-of-hospital CPAP's being cost-effective at the £20,000 per QALY ($29,000/QALY) threshold depended on the incidence of eligible patients and varied from 35.4% when a low estimate of incidence was used to 93.8% with a high estimate. Variation in the incidence of eligible patients also had a marked influence on the expected value of sample information for a future randomized trial.

CONCLUSION

The cost-effectiveness of out-of-hospital CPAP is uncertain. The incidence of patients eligible for out-of-hospital CPAP appears to be the key determinant of cost-effectiveness.

Non-invasive ventilation in the emergency department for patients in type II respiratory failure due to COPD exacerbations

INTRODUCTION

Acute chronic obstructive pulmonary disease (COPD) exacerbations can cause respiratory failure and may require non-invasive ventilation (NIV). There is a paucity of studies examining their NIV implementation within the emergency department (ED).

AIM OF THE STUDY

The aims were (i) to establish whether NIV was beneficial for patients using arterial blood gas analysis (ABG), (ii) to observe whether current ED practice met the guidelines of obtaining ABG measurements within 15 minutes of arrival and commencement of NIV within 1 hour of clinical indication and (iii) to examine which healthcare professionals (HCPs) initiated NIV.

METHODS

A retrospective observational study reviewing all patients commenced on NIV in the ED due to COPD exacerbations was undertaken.

RESULTS

A total of 48 patients were included and the majority received NIV within 1 hour (n =  6, 75%) as recommended by the guidelines. Over 50% of the patients in the study had ABG analysis within 15 minutes and 89% (n = 43) within 30 minutes and statistically significant improvements were noted in respiratory rate, oxygen saturation and ABGs from baseline to repeat measurements undertaken 58 minutes post NIV initiation (p < 0.001). The largest healthcare group to initiate NIV was the nursing team (50% n = 24) with the majority of emergency nurses being experienced nurses [band 6 (n = 17)].

CONCLUSION

From this small single centre study, early ABG analyses and NIV initiation were beneficial to COPD patients presenting in respiratory failure with the majority receiving treatment within the recommended guidelines.

Oxygen therapy in acute exacerbations of chronic obstructive pulmonary disease

Acute exacerbations of chronic obstructive pulmonary disease (COPD) are important events in the history of this debilitating lung condition. Associated health care utilization and morbidity are high, and many patients require supplemental oxygen or ventilatory support. The last 2 decades have seen a substantial increase in our understanding of the best way to manage the respiratory failure suffered by many patients during this high-risk period. This review article examines the evidence underlying supplemental oxygen therapy during exacerbations of COPD. We first discuss the epidemiology and pathophysiology of respiratory failure in COPD during exacerbations. The rationale and evidence underlying oxygen therapy, including the risks when administered inappropriately, are then discussed, along with further strategies for ventilatory support. We also review current recommendations for best practice, including methods for improving oxygen provision in the future.

The use of a prospective audit proforma to improve door-to-mask times for acute exacerbations chronic obstructive pulmonary disease (COPD) requiring non-invasive ventilation (NIV)

Non-invasive ventilation (NIV) is an evidence based management of acidotic, hypercapnic exacerbations of COPD. Previous national and international audits of clinical practice have shown variation against guideline standards with significant delays in initiating NIV. We aimed to map the clinical pathway to better understand delays and reduce the door-to-NIV time to less than 3 hours for all patients with acidotic, hypercapnic exacerbations of COPD requiring this intervention, by mandating the use of a guideline based educational management proforma.The proforma was introduced at 7 acute hospitals in North London and Essex and initiated at admission of the patient. It was used to record the clinical pathway and patient outcomes until the point of discharge or death. Data for 138 patients were collected. 48% of patients commenced NIV within 3 hours with no reduction in door-to-mask time during the study period. Delays in starting NIV were due to: time taken for review by the medical team (101 minutes) and time taken for NIV to be started once a decision had been made (49 minutes). There were significant differences in door-to-NIV decision and mask times between differing respiratory on-call systems, p < 0.05). The introduction of the proforma had no effect on door-to-mask times over the study period. Main reasons for delay were related to timely access to medical staff and to NIV equipment; however, a marked variation in practice within these hospitals was been noted, with a 9-5 respiratory on-call system associated with shorter NIV initiation times.

Invasive and non-invasive mechanical ventilation

Early recognition of patients who might potentially require ventilatory support is a key goal of critical care outreach programs and an important skill for all hospital medical staff. Decisions about the initiation and timing of invasive ventilation can be difficult and early discussion with critical care colleagues is essential. Appropriateness of invasive ventilatory support may also be an issue requiring advanced discussion with patients and their families. In the past 10-15 years, the role of non-invasive ventilation (NIV) has expanded, not least in an attempt to minimize the complications inherent with invasive ventilation. As such, NIV is now considered first-line therapy in some conditions (chronic obstructive pulmonary disease, pulmonary oedema, mild-to-moderate hypoxaemic respiratory failure in immunocompromised patients), and a 'trial of NIV' is often considered in respiratory failure resulting from an increasingly wide range of causes. When using NIV, the importance of the environment (setting, monitoring and experience of staff) and forward planning cannot be overemphasized. When used for other than the standard indications, NIV should be employed in a high-dependency/intensive care setting only in patients for whom invasive ventilation would be considered.

Critical care patients' experience of the helmet continuous positive airway pressure

BACKGROUND

Continuous positive airway pressure (CPAP) is a common treatment modality for acute respiratory failure (ARF) in critical care. Historically, a tight-fitting mask is used to provide respiratory support. This however is not without risks to the patient. The helmet CPAP is a new product that provides the same treatment with a different method of delivery. There is minimal evidence to date explaining the patient's experience of the new helmet modality.

AIMS AND OBJECTIVES

The aim of this research study is to explore critical care patient's experience of helmet CPAP.

DESIGN

A qualitative approach was taken utilizing descriptive phenomenological methodology. In order to obtain rich data, six interviews with cues provided the platform for data generation and collection. A thematic framework was utilized with emergent themes manually analysed using a constant comparative technique to express the experiences or phenomena of a particular event or experiences.

FINDINGS/RESULTS

The overall experience was unique to each patient. The patients entrusted the health care team which made the experience more tolerable. Paradoxical themes were experienced during treatment. The themes included entrapment, confusion, helping me breathe, liberation, challenges, apprehension, relief, trust and endurance. The desire to survive the acute illness proved to be a driving factor.

CONCLUSION

The study has provided an insight into the patient's experience of helmet CPAP in the critical care setting. The findings have provided a basis for policy and guideline development. It will also assist in developing future patient focused care.

The critically ill patient: making the referral to intensive care

Intensive care units are responsible for looking after patients with reversible life-threatening conditions, who need frequent and often invasive monitoring as well as support from mechanized equipment and pharmacological therapies to maintain normal body function and physiological parameters. A previous article highlighted how to recognize and stabilize the sick patient (Elnour and Shankar-Hari, 2011). Some patients may continue to deteriorate despite appropriate and prompt intervention. This article outlines the criteria for advanced life support interventions and hence admission to critical care. The focus of discussion will be patients in need of level 2 to 3 care requiring priority 1 to 2 admissions.

Non-invasive ventilation: established and expanding roles

Non-invasive ventilation (NIV) has become the standard of care for most patients with ventilatory failure due to an acute exacerbation of chronic obstructive pulmonary disease (COPD). In all but a small minority, even of the very sickest, there is little to be lost by at least a short trial of NIV. In patients with acute cardiogenic pulmonary oedema, NIV results in a more rapid physiological improvement and resolution of dyspnoea, but the benefits in terms of survival have been called into question by two recent randomised controlled trials. There are no randomised controlled trials of NIV in patients with acute ventilatory failure due to obesity but the outcome from invasive ventilation is poor and the results of NIV encouraging. Finally, NIV may have a role during the transition from active care, aimed to extend life, to palliative care.

Management of acute exacerbations of chronic obstructive pulmonary disease: the first 24 hours

Successful outcome is more likely with early treatment and lesser degrees of acidosis. While aiming for maximum treatment for the first 24 hours, some patients improve so rapidly that they can discontinue after a shorter time. Most patients need a full face mask and oxygen, and nebulised bronchodilators can be incorporated. If radiological consolidation, excessive secretions and/or confusion are present, the chance of failure is increased but is not an absolute contraindication. The presence of a pneumothorax necessitates intercostal drainage. A useful summary statement has recently been published. Patients who are obtunded and peri-arrest require immediate intubation and mechanical ventilation. There is some evidence that intensivists are reluctant to accept COPD exacerbators to the intensive care unit because of the perceived low survival rates or concerns about weaning delays after intubation. In fact, the prognosis may be better than in many other patients with multi-organ failure. Patients can often be quickly weaned on to NIV and returned to the ward after an initial period of invasive support and secretion management. Initial assessment and the past history should identify those markedly disabled patients with recurrent admissions who are likely to be entering the terminal stages of their illness in whom intubation is inappropriate. Here, NIV may be the ceiling of treatment, providing useful symptom palliation while waiting for treatment to

Non-invasive ventilation for acute exacerbations of COPD

Acute exacerbations of chronic obstructive pulmonary disease (COPD) causing respiratory failure are associated with mortality rates of up to 26%. A new Royal College of Physicians guideline aims to impart standards and practical advice to those providing a non-invasive ventilation service for these patients. This article examines the guideline.

Mercury inhibition of avian fatty acid synthetase complex

(1) Subcutaneous or intra-abdominal injections of 8 mg of HgCl2/100 g body weight markedly depressed hepatic fatty acid synthetase activity of chicks at 1 h post-injection. The depression occurred despite the fact that the chicks continued to eat up until the time they were killed. Under these same conditions, the hepatic activity of acetyl-CoA carboxylase (EC 6.4.1.2) was not affected by HgCl2, while the activity of the mitochondrial system of fatty acid elongation was stimulated. (2) When 2-mercaptoethanol was included in the incubation medium for a highly purified preparation of fatty acid synthetase, 500 muM HgCl2 was required to show definite inhibition of the enzyme. When 2-mercaptoethanol was omitted, 50 muM HgCl2 was inhibitory and 100 muM HgCl2 abolished enzyme activity. (3) 2 mM dithiothreitol completely protected the purified fatty acid synthetase preparation from inhibition by 100 muM HgCl2. When dithiothreitol was added after the addition of enzyme to the mercury-containing medium, protection of the enzyme was not complete. (4) Dialysis of cytosol fractions from chicks injected with HgCl2 against 500 vol. of 0.2 M potassium phosphate buffer (pH 7.0) containing 1 mM EDTA and 10 mM dithiothreitol for 4 h at 4 degrees stimulated the fatty acid synthetase activity of the fractions. Dialysis of cytosol fractions from noninjected chicks under the same conditions was without effect on fatty acid synthetase activity. (5) These data support the hypothesis that the inhibitory effect of HgCl2 administered in vivo on hepatic fatty acid synthetase activity in chicks is mediated through the interaction of mercury with the sulfhydryl groups of the enzyme.