Noninvasive positive-pressure ventilation in patients with acute respiratory failure

Development of a non-invasive ventilator for emergency and beyond

The SARS-CoV-2 pandemic led to the development and implementation of emergency ventilators owing to the shortage of ventilators globally. Using invasive ventilators for patient intubation has medical experts concerned about increasing mortality. Early intervention with oxygen and respiratory therapy reduces the need for intubation, increases survival rates, and reduces the stress of critical care ventilators in hospitals. This study explores the capabilities of an easy-to-build and accessible non-invasive ventilator during an emergency and the practical implementation of the ventilator beyond the scope of the emergency. The proposed system consists of a high-pressure turbine integrated with a microcontroller and pressure and flow sensors assembled in a portable design. The non-invasive pressure support system is tested with a single-chamber high-precision lung simulator capable of simulating multiple lung diseases. The system is operated in a spontaneous pressure support mode as a Bi-level Ventilator for varying degrees of pressure level and lung conditions. The proposed study implements two most commonly adapted non-invasive patient circuits, i.e., single passive limb leak circuit and single limb active circuit. Both circuits are tested with and without leakage compensation. Two clinically accepted ventilation modes, i.e., pressure support and volume-assured pressure support ventilation, are presented. The results demonstrate the feasibility of using this type of device for non-invasive respiratory support and highlight the need for further testing to assess its safety and effectiveness in various clinical settings.

Development of a deep learning model that predicts Bi-level positive airway pressure failure

Delaying intubation for patients failing Bi-Level Positive Airway Pressure (BIPAP) may be associated with harm. The objective of this study was to develop a deep learning model capable of aiding clinical decision making by predicting Bi-Level Positive Airway Pressure (BIPAP) failure. This was a retrospective cohort study in a tertiary pediatric intensive care unit (PICU) between 2010 and 2020. Three machine learning models were developed to predict BIPAP failure: two logistic regression models and one deep learning model, a recurrent neural network with a Long Short-Term Memory (LSTM-RNN) architecture. Model performance was evaluated in a holdout test set. 175 (27.7%) of 630 total BIPAP sessions were BIPAP failures. Patients in the BIPAP failure group were on BIPAP for a median of 32.8 (9.2-91.3) hours prior to intubation. Late BIPAP failure (intubation after using BIPAP > 24 h) patients had fewer 28-day Ventilator Free Days (13.40 [0.68-20.96]), longer ICU length of stay and more post-extubation BIPAP days compared to those who were intubated ≤ 24 h from BIPAP initiation. An AUROC above 0.5 indicates that a model has extracted new information, potentially valuable to the clinical team, about BIPAP failure. Within 6 h of BIPAP initiation, the LSTM-RNN model predicted which patients were likely to fail BIPAP with an AUROC of 0.81 (0.80, 0.82), superior to all other models. Within 6 h of BIPAP initiation, the LSTM-RNN model would identify nearly 80% of BIPAP failures with a 50% false alarm rate, equal to an NNA of 2. In conclusion, a deep learning method using readily available data from the electronic health record can identify which patients on BIPAP are likely to fail with good discrimination, oftentimes days before they are intubated in usual practice.

Noninvasive ventilation can modulate heart rate variability during high-intensity exercise in COPD-CHF patients

OBJECTIVE

to assess the acute effects of non-invasive ventilation (NIV) during high-intensity exercise on heart rate variability (HRV) responses in chronic obstructive pulmonary disease (COPD) and Chronic heart failure (CHF) patients.

METHODS

This was randomized, double blinded and controlled study. Fourteen patients with COPD-HF diagnosis were evaluated. The subjects underwent to the following tests: (I) cardiopulmonary exercise testing (CPET) on a cycle ergometer ramp protocol; (II) 7 days after CPET, patients randomly underwent two constant-load exercise (CLE) with NIV or Sham ventilation until tolerance limit, with 80% of the CPET peak load. R-R intervals (RRi) were continuously collected during rest, exercise and in recovery. Time and frequency domain and nonlinear heart rate variability (HRV) indices were obtained.

RESULTS

NIV resulted in a decrease of Mean iRR, square root of the mean squared differences of successive RRi (rMSSD), RR tri index and high-frequency (HF), nu (p < 0.05) and increase of Mean HR, low-frequency (LF), nu and LF/HF (p < 0.05) during exercise when compared to rest. In addition, NIV during exercise induced lower rMSSD and Sample Entropy when compared with Sham (p < 0.05). Negative correlation was found between forced expiratory volume in 1 second (FEV_1, L) vs HF (nu) during exercise with NIV (p = 0.04; r= -0.58). Furthermore, simple linear regression showed that the FEV₁ (L) affected 30% of the HF (nu) response during the exercise with NIV.

CONCLUSION

NIV during exercise produced enhanced heart rate and autonomic responses in COPD-CHF patients. Additionally, COPD severity is negatively associated with a higher vagal response during exercise with NIV.

Airways and Injuries: Protecting Our Pediatric Patients from Respiratory Device-Related Pressure Injuries

Pressure injury prevention is required in all health care environments. Respiratory technology includes invasive and noninvasive positive pressure ventilation methods of support and life-saving equipment. Pressure injury can occur from tracheostomy tubes and their securement devices, or use of noninvasive positive pressure ventilation interfaces or the head gear. Methods instituted to decrease hospital-acquired pressure injury related to noninvasive positive pressure ventilation and tracheostomy securement devices are discussed.

Impact of CPAP on physical exercise tolerance and sympathetic-vagal balance in patients with chronic heart failure

Background:

Chronic heart failure (CHF) leads to exercise intolerance. However, non-invasive ventilation is able to improve functional capacity of patients with CHF.

Objectives:

The aim of this study was to evaluate the effectiveness of continuous positive airway pressure (CPAP) on physical exercise tolerance and heart rate variability (HRV) in patients with CHF.

Method

: Seven men with CHF (62±8 years) and left ventricle ejection fraction of 41±8% were submitted to an incremental symptom-limited exercise test (IT) on the cicloergometer. On separate days, patients were randomized to perform four constant work rate exercise tests to maximal tolerance with and without CPAP (5 cmH₂O) in the following conditions: i) at 50% of peak work rate of IT; and ii) at 75% of peak work rate of IT. At rest and during these conditions, instantaneous heart rate (HR) was recorded using a cardiofrequencimeter and HRV was analyzed in time domain (SDNN and RMSSD indexes). For statistical procedures, Wilcoxon test or Kruskall-Wallis test with Dunn's post-hoc were used accordingly. In addition, categorical variables were analysed through Fischer's test (p<0.05).

Results:

There were significant improvements in exercise tolerance at 75% of peak work rate of IT with CPAP (405±52 vs. 438±58 s). RMSSD indexes were lower during exercise tests compared to CPAP at rest and with 50% of peak work rate of IT.

Conclusion:

These data suggest that CPAP appears to be a useful strategy to improve functional capacity in patients with CHF. However, the positive impact of CPAP did not generate significant changes in the HRV during physical exercises.

Facial pressure zones of an oronasal interface for noninvasive ventilation: a computer model analysis

OBJECTIVE:

To study the effects of an oronasal interface (OI) for noninvasive ventilation, using a three-dimensional (3D) computational model with the ability to simulate and evaluate the main pressure zones (PZs) of the OI on the human face.

METHODS:

We used a 3D digital model of the human face, based on a pre-established geometric model. The model simulated soft tissues, skull, and nasal cartilage. The geometric model was obtained by 3D laser scanning and post-processed for use in the model created, with the objective of separating the cushion from the frame. A computer simulation was performed to determine the pressure required in order to create the facial PZs. We obtained descriptive graphical images of the PZs and their intensity.

RESULTS:

For the graphical analyses of each face-OI model pair and their respective evaluations, we ran 21 simulations. The computer model identified several high-impact PZs in the nasal bridge and paranasal regions. The variation in soft tissue depth had a direct impact on the amount of pressure applied (438-724 cmH₂O).

CONCLUSIONS:

The computer simulation results indicate that, in patients submitted to noninvasive ventilation with an OI, the probability of skin lesion is higher in the nasal bridge and paranasal regions. This methodology could increase the applicability of biomechanical research on noninvasive ventilation interfaces, providing the information needed in order to choose the interface that best minimizes the risk of skin lesion.

Noninvasive support and ventilation for pediatric acute respiratory distress syndrome: proceedings from the Pediatric Acute Lung Injury Consensus Conference

OBJECTIVE

Despite the widespread use of noninvasive ventilation in children and in children with acute lung injury and pediatric acute respiratory distress syndrome, there are few scientific data on the utility of this therapy. In this review, we examine the literature regarding noninvasive positive pressure ventilation and use the Research ANd Development/University of California, Los Angeles appropriateness methodology to provide strong or weak recommendations for the use of noninvasive positive pressure ventilation in children with pediatric acute respiratory distress syndrome.

DATA SOURCES

Electronic searches were made in PubMed, EMBASE, Web of Science, Cochrane Library, and Scopus with the following specific keywords: noninvasive ventilation, noninvasive positive pressure ventilation, continuous positive airway pressure, and high-flow nasal cannula.

STUDY SELECTION

Studies were eligible for inclusion if they included 10 or more children between 1 month and 18 years old. Randomized and nonrandomized controlled trials, controlled before-and-after studies, concurrent cohort studies, interrupted time series studies, historically controlled studies, cohort studies, cross-sectional studies, and uncontrolled longitudinal studies were included for data synthesis.

DATA SYNTHESIS

The literature provides a solid physiological rationale for the use of noninvasive positive pressure ventilation in children with pediatric acute respiratory distress syndrome. The addition of noninvasive positive pressure ventilation can improve gas exchange and potentially prevent intubation and mechanical ventilation in some children with mild pediatric acute respiratory distress syndrome. Noninvasive positive pressure ventilation is not indicated in severe pediatric acute respiratory distress syndrome. Noninvasive positive pressure ventilation should be performed only in acute care setting with experienced team, and patient-ventilator synchrony is crucial for success. An oronasal interface provides superior support, but close monitoring of children is required due to the risk of progressive respiratory failure and the potential need for intubation. The use of high-flow nasal cannula is a promising treatment for respiratory disease; however, at this time, the efficacy of high-flow nasal cannula compared with noninvasive positive pressure ventilation is unknown.

CONCLUSION

Noninvasive positive pressure ventilation can be beneficial in children with pediatric acute respiratory distress syndrome, particularly in those with milder disease. However, further research is needed into the use of noninvasive positive pressure ventilation in children.

Noninvasive ventilation and exercise tolerance in heart failure: A systematic review and meta-analysis

Background:

Patients with heart failure (HF) usually develop exercise intolerance. In this context, noninvasive ventilation (NIV) can help to increase physical performance.

Objective:

To undertake a systematic review and meta-analysis of randomized controlled trials that evaluated the effects of NIV on exercise tolerance in patients with HF.

Method:

Search Strategy: Articles were searched in the following databases: Physiotherapy Evidence Database (PEDro), Scientific Electronic Library Online (SciELO), and MEDLINE. Selection Criteria: This review included only randomized controlled trials involving patients with HF undergoing NIV, with or without other therapies, that used exercise tolerance as an outcome, verified by the distance travelled in the six-minute walk test (6MWT), VO₂peak in the cardiopulmonary test, time spent in testing, and dyspnea. Data Collection and Analysis: The methodological quality of the studies was rated according to the PEDro scale. Data were pooled in fixed-effect meta-analysis whenever possible.

Results:

Four studies were selected. A meta-analysis including 18 participants showed that the use of NIV prior to the 6MWT promoted increased distance, [mean difference 65.29 m (95% CI 38.80 to 91.78)].

Conclusions:

The use of NIV prior to the 6MWT in patients with HF may promote increased distance. However, the limited number of studies may have compromised a more definitive conclusion on the subject.

Non-invasive ventilation for children with acute respiratory failure in the developing world: literature review and an implementation example

Over 2 million children die of acute respiratory infection every year, with around 98% of these deaths occurring in developing countries. Depending upon the clinical status of the patient, supplemental oxygen is usually the first line therapy. However this often proves inadequate for acute respiratory failure (ARF), in which case intubation and mechanical positive pressure ventilation are required. Adult intensive care successfully introduced non-invasive positive pressure ventilation (NIPPV) to treat ARF over a decade ago. This experience, coupled with the use of NIPPV in children with chronic respiratory insufficiency, has led to increasing use of NIPPV to treat ARF in paediatric populations. NIPPV can have similar or improved outcomes to IPPV, but with fewer complications. However there are no controlled trials of its use in children, and most data come from observational studies and retrospective reviews. In a developing world setting, where mortality from ARF is high and the risks of intubation are great and often not feasible, NIPPV can be a simple and cost-effective way to treat these patients. Its implementation in rural Northern Ghana shows NIPPV for ARF can be delivered safely with minimal training, and appears to impact significantly on mortality in those under 5 years.

Comparative evaluation of three interfaces for non-invasive ventilation: a randomized cross-over design physiologic study on healthy volunteers

Introduction

Interface choice is crucial for non-invasive ventilation (NIV) success. We compared a new interface, the helmet next (H_N), with the facial mask (FM) and the standard helmet (H_S) in twelve healthy volunteers.

Methods

In this study, five NIV trials were randomly applied, preceded and followed by a trial of unassisted spontaneous breathing (SB). Baseline settings, for example, 5 cmH₂O of both inspiratory pressure support (PS) and positive end-expiratory pressure (PEEP), were applied through FM, H_S and H_N, while increased settings (PS and PEEP of 8 cmH₂O) were only applied through H_S and H_N. We measured flow, airway, esophageal and gastric pressures, and calculated inspiratory effort indexes and trigger delays. Comfort was assessed with a visual-analog-scale.

Results

We found that FM, H_S and H_N at baseline settings were not significantly different with respect to inspiratory effort indexes and comfort. Inspiratory trigger delay and time of synchrony (TI,synchrony) were significantly improved by FM compared to both helmets, whereas expiratory trigger delay was shorter with FM, as opposed to H_S only. H_N at increased settings performed better than FM in decreasing inspiratory effort measured by pressure-time product of transdiaphragmatic pressure (PTPdi)/breath (10.7 ± 9.9 versus 17.0 ± 11.0 cmH₂O*s), and PTPdi/min (128 ± 96 versus 204 ± 81 cmH₂O*s/min), and PTPdi/L (12.6 ± 9.9 versus 30.2 ± 16.8 cmH₂O*s/L). TI, synchrony was inferior between H_N and H_S at increased settings and FM.

Conclusions

H_N might hold some advantages with respect to interaction and synchrony between subject and ventilator, but studies on patients are needed to confirm these findings.

Trial registration

ClinicalTrials.gov NCT01610960

Role of BiPAP applied through endotracheal tube in unconscious patients suffering from acute exacerbation of COPD: a pilot study

BACKGROUND AND OBJECTIVES

Mechanical ventilation is the recommended treatment in unconscious patients with acute exacerbation of chronic obstructive pulmonary disease (COPD) and hypercapenic respiratory failure. But, in resource-poor countries, many of these patients are not able to afford this treatment due to financial constraints. The main aim of this study was to evaluate the usefulness, safety and cost-effectiveness of bilevel positive airway pressure (BiPAP) applied via endotracheal tube in such patients.

METHODS

Twenty patients with acute exacerbation of COPD and altered sensorium, who were unable to afford ventilatory support, were intubated and BiPAP therapy was provided to these patients through the endotracheal tube. The outcome of these patients was studied.

RESULTS

The BiPAP success rate and hospital mortality were 85% (17/20) and 15% (3/20) respectively. BiPAP failure was associated with high sequential organ failure assessment (SOFA) score at the time of admission (P = 0.002). Improvement in Glasgow coma scale (GCS) score (P < 0.001), pH (P = 0.001), PaCO(2) (partial pressure of carbon dioxide) (P < 0.001), respiratory rate (P < 0.001), and SOFA score (P = 0.001) was observed among the responders following 2 hours of therapy. Only one of the responders developed aspiration pneumonitis, as a complication. The daily cost of BiPAP therapy was 8.75 times lower than the average cost of mechanical ventilation.

CONCLUSION

This pilot study reveals that this treatment modality could be a safe, cost-effective and efficacious method of treatment in unconscious patients with acute exacerbation of COPD.

[Does noninvasive ventilation avoid intubation of the critical patient?]

In recent years we have witnessed an increased use of noninvasive ventilation (NIV) in our intensive care units (ICUs). Its use is intended mainly in cases of acute respiratory failure (ARF), in order to improve arterial oxygenation, increase alveolar ventilation, decrease work of breathing and avoid intubation. For this reason, we designed a study that has aimed to quantify the number of patients who have benefited from NIV during their admission, to know the type of NIV used in these patients and to determine whether the use of NIV has avoided tracheal intubation. We performed a retrospective, observational and descriptive study in two polyvalent ICUs of a tertiary hospital, with 80 patients with NIV during admission. 65% men and 35% women. Mean age: ±61 years (47-75). Average stay: ±10 days (2-18). NIV mode used was double positive pressure with Nellcor Puritan Bennett® 840. A total of 46% of patients treated with NIV required intubation, thus extending their stay in the ICU by ±6 days. Most patients treated with NIV had a history of chronic obstructive pulmonary disease (COPD) and / or were carriers of VNI with continuous positive pressure (CPAP) at home. Following this analysis, we concluded that treatment with NIV did not prevent tracheal intubation in a considerable number of patients (37) diagnosed with ARF and the NIV was effective in patients with a history of COPD and / or CPAP at home.

Noninvasive ventilation in adults with acute respiratory distress: a primer for the clinician

Noninvasive ventilation (NIV) has become an integral part of critical care management. Despite > 2 decades of experience, it is relatively underused, with general utilization reported as a little over 10% in a recent international survey. Lack of training, knowledge, equipment, and experience with NIV may account for its slow adoption. Patient selection, staff training and experience, and prompt recognition of ineffective NIV are important components to successful application of NIV. Noninvasive ventilation does have a learning curve that may be steep for some institutions but must be mastered if the procedure is to become a successful institutional component of care. Patients with acute respiratory failure due to chronic obstructive pulmonary disease or congestive heart failure are ideal candidates for NIV, and optimal efficacy in associated conditions is often linked to these 2 conditions. Technical issues and written guidelines are addressed, including details of an adequate trial of therapy as well as criteria for intubation. Attention to these elements should increase the success rate of NIV, which in turn should increase its general use.

Predictive factors of non invasive ventilation failure in critically ill children: a prospective epidemiological study

OBJECTIVE

Identification of predictive factors for non-invasive ventilation (NIV) failure and determination of NIV characteristics.

DESIGN

Prospective observational study.

SETTING

Paediatric Intensive Care Unit in a University Hospital.

PATIENTS AND MEASUREMENTS

A total of 116 episodes were included. Clinical data collected were respiratory rate (RR), heart rate and FiO(2) before NIV began. Same data and expiratory and support pressures were collected at 1, 6, 12, 24 and 48 h. Conditions precipitating acute respiratory failure (ARF) were classified into two groups: type 1 (38 episodes) and type 2 (78 episodes). Ventilation-perfusion impairment was the main respiratory failure mechanism in type 1, and hypoventilation in type 2. Factors predicting NIV failure were determined by multivariate analysis.

RESULTS

Most common admission diagnoses were pneumonia (81.6%) in type 1 and bronchiolitis (39.7%) and asthma (42.3%) in type 2. Complications secondary to NIV were detected in 23 episodes (20.2%). NIV success rate was 84.5% (68.4% in type 1 and 92.3% in type 2). Type 1 patients showed a higher risk of NIV failure compared to type 2 (OR 11.108; CI 95%, 2.578-47.863). A higher PRISM score (OR 1.138; CI 95%, 1.022-1.267), and a lower RR decrease at 1 h and at 6 h (OR 0.926; CI 95%, 0.860-0.997 and OR 0.911; CI 95%, 0.837-0.991, respectively) were also independently associated with NIV failure.

CONCLUSIONS

NIV is a useful respiratory support technique in paediatric patients. Type 1 group classification, higher PRISM score, and lower RR decrease during NIV were independent risk factors for NIV failure.

Noninvasive ventilation in patients with hypoxemic acute respiratory failure

PURPOSE OF REVIEW

To discuss the recent literature concerning the use of noninvasive ventilation for hypoxemic acute respiratory failure.

RECENT FINDINGS

The benefits of noninvasive ventilation for patients with hypoxemic acute respiratory failure are unclear. In immunocompromised patients and following thoracic surgery, there is a strong rationale for using noninvasive ventilation to treat acute respiratory failure. Prophylactic continuous positive airway pressure after abdominal or thoracic surgery and prophylactic noninvasive ventilation in patients at risk of extubation failure have proved beneficial. Recent studies show that noninvasive ventilation has a favourable impact in immunocompetent patients with acute lung injury/acute respiratory distress syndrome, but caution is required. In hypoxemic acute respiratory failure after extubation, one study reported excess mortality in patients treated with noninvasive ventilation, possibly related to the delay for intubation. A major issue is avoiding undue noninvasive ventilation prolongation and staying alert for predictors of early noninvasive ventilation failure. Caution, close monitoring, and broad experience are required.

SUMMARY

Hypoxemic acute respiratory failure may benefit from noninvasive ventilation or continuous positive airway pressure, but undue prolongation should be avoided. In postextubation respiratory failure there is no evidence for routine use of noninvasive ventilation.

Noninvasive ventilation

Noninvasive positive-pressure ventilation (NPPV) is the delivery of mechanical-assisted breathing without placement of an artificial airway such as an endotracheal tube or tracheostomy. During the first half of 20th century, negative-pressure ventilation (iron lung) provided mechanical ventilatory assistance. By the 1960s, however, invasive (ie, by means of an endotracheal tube) positive-pressure ventilation superseded negative-pressure ventilation as the primarily mode of support for ICU patients because of its superior delivery of support and better airway protection. Over the past decade, the use of NPPV has been integrated into the treatment of many medical diseases, largely because the development of nasal ventilation. Nasal ventilation has the potential benefit of providing ventilatory assistance with greater convenience, comfort, safety, and less cost than invasive ventilation. NPPV is delivered by a tightly fitted mask or helmet that covers the nares, face, or head. NPPV is used in various clinical settings and is beneficial in many acute medical situations. This article explores the trends regarding the use of noninvasive ventilation. It also provides a current perspective on applications in patients with acute and chronic respiratory failure, neuromuscular disease, congestive heart failure, and sleep apnea. Additionally, it discusses the general guidelines for application, monitoring, and avoidance of complications for NPPV.

Non-invasive positive pressure ventilation in acute respiratory failure: providing competent care

Non-invasive positive pressure ventilation (NPPV) has been used as an alternative strategy to provide ventilatory support for patients with acute respiratory failure. Most studies demonstrate that the use of NPPV in acute respiratory failure results in a reduction in the need for endotracheal intubation and an overall survival advantage. However, current evidence, in the form of randomised controlled trials, suggests that these benefits may be restricted to patients suffering from acute exacerbation of chronic obstructive pulmonary disease (COPD). The clinical application of NPPV involves the development of competence in delivering the particular intervention. Clinical outcomes and thus valid comparisons with alternate methods of ventilatory support can only be made if attention is paid to the clinical indications for the application of NPPV and patient subgroups it is used to treat and the level of competence of care givers in its application and delivery. One essential element of competence is the establishment of an appropriate knowledge base and the development of clinical practice guidelines. This literature review identifies the current indications for NPPV and the relevant information for developing clinical practice guidelines for the management of this form of ventilatory support.

Clinical review: New technologies -- venturing out of the intensive care unit

The delivery of critical care is no longer limited to the intensive care unit. The information gained by utilization of new technologies has proven beneficial in some populations. Research into earlier and more widespread use of these modalities may prove to be of even greater benefit to critically ill patients.

Factores de predicción del éxito de la ventilación no invasiva en el tratamiento del edema agudo de pulmón cardiogénico

BACKGROUND AND OBJECTIVE

Recent studies support the use of non invasive ventilation (NIV) in patients with acute cardiogenic pulmonary edema (ACPE). We aimed to evaluate the factors related to the success of the technique in patients admitted to an intensive care unit (ICU) with ACPE.

PATIENTS AND METHOD

An observational prospective study was performed in ICU.199 consecutive patients were enrolled with ACPE at admission who received treatment with NIV and standardized pharmacological treatment. The success of the NIV was achieved when endotracheal intubation was avoided and patients were alive without dyspnea within and 24 hours after discharge from the ICU. Clinical, physiological and gasometric parameters were analyzed at admission and one hour after starting NIV.

RESULTS

Patient's age was 74 years. 43% were male. The SAPS II was 45. 74.4% of the patients were successfully treated with NIV. 12.6% required endotracheal intubation. In a multivariate analysis, the success of the technique (values expressed as odds ratio [95% confidence interval]) was related to: SAPS II (0.95 [0.91-0.99]); the place of admission (6.78 [1.85-24.79]); value of PCO2 at admission (1.05 [1.01-1.09]); PO2/FiO2 index (1.03 [1.01-1.06]) and respiratory frequency (0.91 [0.84-0.99]) within the first hour; SOFA (acute failure organics score) (0.62 [0.49-0.78]); concomittant acute myocardial infarction (AMI) (0.05 [0.01-0.22]) and number of complications (0.17 [0.47-0.65]). The hospital mortality rate was 32.7%. The non intubation order (0.12 [0.04-0.32]) and the success of the technique (100.03 [28.71-348.47]) were related to the hospital mortality.

CONCLUSIONS

The success of NIV in the treatment of ACPE is related to a lower SAPS II, admission at the emergency department, elevated PCO2 at admission, improvement of the PO2/FiO2 index and the respiratory rate within the first hour. The non intubation order and the success of the technique were related to the hospital mortality.

Clinical practice guideline for the use of noninvasive positive pressure ventilation in COPD patients with acute respiratory failure

Noninvasive positive pressure ventilation has been demonstrated to be of benefit in preventing endotracheal intubation and reducing mortality in specific patients in the setting of acute exacerbations of chronic obstructive pulmonary disease. The successful application of noninvasive positive pressure ventilation depends on a multitude of factors, including patient selection, choice of interface, physician experience, and patient-ventilator synchrony. The use of clinical practice guidelines has been shown to improve the process and outcomes of care. This paper presents a guideline for the use of noninvasive positive pressure ventilation in the setting of acute ventilatory failure in patients with acute exacerbations of chronic obstructive pulmonary disease.

Survey of interventions for the prevention and treatment of acute respiratory distress syndrome

OBJECTIVE

To determine physicians' opinions and practices related to the management of patients with acute respiratory distress syndrome.

DESIGN

Cross-sectional mail survey.

SETTING

Province of Ontario, Canada.

PARTICIPANTS

Physicians treating patients with acute respiratory distress syndrome at university-affiliated and unaffiliated hospitals.

INTERVENTIONS

We searched the literature and consulted experts to generate a list of potential interventions for acute respiratory distress syndrome. Eight intensive care unit physicians selected the most relevant, available, and controversial of these interventions for prevention (n = 5) and treatment (n = 30). Fourteen physicians reviewed the questionnaire before administration to ensure clarity, realism, and clinical sensibility. We asked participants to report their views on a) the efficacy of each intervention; b) published research evaluating efficacy; c) the frequency with which they use each intervention; and d) determinants of utilization.

MEASUREMENTS AND MAIN RESULTS

One hundred ten of 194 eligible physicians responded. Respondents varied considerably in their reported use of the 35 interventions. Although physicians cited published research findings as the most powerful determinant of prescribing these interventions, they were unaware of many relevant trials. Physicians also commonly cited "usual local practice" as a determinant of use, although formal practice guidelines were rarely in operation. Other variables directly associated with use of these interventions included increasing frequency of exposure to acute respiratory distress syndrome (p <.0001), increasing size of the intensive care unit in which physicians work (p =.004), and the presence of residents in the intensive care unit (p =.02).

CONCLUSIONS

Wide variation in the management of acute respiratory distress syndrome appears related to limited awareness of relevant research, conflicting interpretations of research findings, and adherence to varying local practice patterns. Given physicians' desire to tailor their practice to research findings and to practice in a manner that is consistent with their local intensive care unit colleagues, future research and educational efforts related to evidence-based protocols for the management of patients with acute respiratory distress syndrome might be worthwhile.

Efficacy and tolerability of non-invasive ventilation delivered via a newly developed helmet in immunosuppressed patients with acute respiratory failure

OBJECTIVES

To assess efficacy and tolerability of a newly developed helmet for the delivery of non-invasive ventilation in patients with acute respiratory failure.

PATIENTS AND METHODS

Ten consecutive immunocompromised patients with acute respiratory failure admitted to our intensive care unit were included in the study. The patients were equipped with the helmet and non-invasive ventilation (NIV) was performed. Oxygenation and tolerability were assessed during the first 24 hours of NIV.

RESULTS

All patients tolerated the helmet well and their oxygenation improved. Two patients developed septic shock and had to be endotracheally intubated during the study period, eight patients survived to be weaned from NIV.

CONCLUSIONS

NIV delivered via the helmet is effective and may serve as a better tolerated alternative to endotracheal intubation and to NIV via a standard face mask.

Every breath you take

Recent advancements to ventilators and interface choices have increased noninvasive positive pressure ventilation usage in long-term and intensive care settings.

Non-invasive BiPAP--implementation of a new service

Non-invasive ventilation has been shown to be an effective treatment for acute hypercapnic respiratory failure. It is now increasingly used in the treatment of acute hypoxemic respiratory failure. National guidelines published by the British Thoracic Society state that facilities for NIV should be available 24 hours per day in all hospitals likely to admit such patients. If an acute NIV service is not provided, the shortage of Intensive Care beds means that some patients will die because facilities to invasively ventilate are not available. Conversely, results of a survey performed by the indicate that at the time of data collection, only 48% of United Kingdom hospitals provided an acute NIV service. The BiPAP Vision (Respironics Inc.) offers Continuous Positive Airway Pressure (CPAP), Bi-level Spontaneous/Timed and Proportional Assist Ventilation/Timed modes and is ideal for use in a critical care environment. This article presents some of the issues surrounding NIV, the impact of a new service, and the process of implementing NIV within a critical care setting.

Survey of non-invasive ventilation for acute exacerbation of chronic obstructive pulmonary disease patients in emergency departments in Belgium

A study was undertaken to assess the availability and use of non-invasive ventilation (NIV) for the treatment of acute exacerbation of chronic obstructive pulmonary disease (COPD) in emergency departments in Belgium. A questionnaire was sent to the head physicians of 145 emergency departments (EDs) found in the list of the Belgian College of Emergency Physicians (BeCEP). Ninety eight questionnaires were analysed (representing 68% of the questionnaires sent). NIV was used in 49% of the EDs. In the hospitals where NIV was not used, the most important reasons given were no available equipment in 71%, lack of experience with this form of treatment in 32.7%, and more time consuming for physicians and nursing staff in 22.8%. Only 3.8% of the physicians doubted the benefit of NIV treatment. In the hospitals where NIV was used, the patient was watched during the first hour by one nurse only in 19.6%, by one physician in 8.6% and by a nurse and a physician in 54.5%. NIV was used for more than 4 h in 33% of EDs. Pressure-controlled ventilation (with home respirators) was used more often than volume-controlled ventilation.

The evaluation and management of acute, severe asthma

This article provides a systematic approach to the patient with acute, severe asthma. After a brief, focused evaluation prompt treatment with inhaled beta 2-agonists and systemic corticosteroids remains the cornerstone of treatment. Ipratropium bromide is now recognized as a useful addition for both adult and pediatric populations, whereas consideration of intravenous MgSO4 and theophylline is warranted for refractory patients. Ongoing evaluation of antileukotriene agents offers a possibility of these agents as alternative bronchodilators. Further research with a number of potential acute asthma agents will further expand treatment options for rapid symptomatic airway improvement and prevention of progressing airway obstruction, hospitalization, and potential respiratory failure.

Effect of a nonrebreathing exhalation valve on long-term nasal ventilation using a bilevel device

STUDY OBJECTIVE

To determine whether an exhalation valve designed to minimize rebreathing improves daytime or nocturnal gas exchange or improves symptoms compared with a traditional valve during nocturnal nasal ventilation delivered using a bilevel pressure ventilation device.

DESIGN

Prospective direct comparison trial with each patient sequentially using both valves, during a 2-week run-in period with a traditional valve, a 2-week trial with the nonrebreathing valve, and a 2-week washout period with the traditional valve.

SETTING

Outpatient pulmonary function laboratory and home nocturnal monitoring.

PATIENTS

Seven patients who received long-term (> 1 year) nocturnal nasal bilevel pressure ventilation with an expiratory pressure of <or= 4 cm H(2)O.

INTERVENTION

Symptoms, pulmonary function, and arterial blood gas levels were assessed at each of three daytime sessions after the sequential 2-week periods using the different valves. Nocturnal studies used a multichannel recorder that measured heart rate, chest wall impedance, nasal airflow, and oximetry. End-tidal PCO(2) (PetCO(2)) from the mask and transcutaneous PCO(2) (PtcCO(2)) were also monitored nocturnally.

RESULTS

Seven patients with a variety of neuromuscular, chest wall, and obstructive defects were enrolled. No mean differences in daytime arterial blood gas levels, pulmonary functions, nocturnal vital signs or oximetry, or PtcCO(2) were apparent regardless of the exhalation valve used. The multichannel recording was indicative of an air leak at least one third of the time, and the PetCO(2) tracing detected a blunted signal or no signal from the mask during the majority of the recording time.

CONCLUSION

The use of an exhalation valve designed to minimize rebreathing did not improve daytime or nocturnal gas exchange or symptoms in patients receiving long-term nasal bilevel pressure ventilation in comparison with a traditional exhalation valve, most likely because of air leakage and escape of CO(2) via other routes.

Liberation from prolonged mechanical ventilation

After weaning from PMV, patients are usually far from ready to resume normal activities. A prolonged recovery period after catastrophic illness is the rule, with multidisciplinary rehabilitation and discharge planning efforts. Following such efforts, reports of success of restorative care are institutional and population specific. That all PMV patients are not "chronically critically ill" introduces selection factors that make comparisons between institutions even more difficult. Half of the authors' patients were able to go home in past years [14], although more recently, with patients admitted more debilitated and more ill, the percent returning home has gradually declined to the low 20% range. Bagley et al [11] report discharge to home in 31% of patients weaned. Gracey et al [6,133], treating younger, postsurgical patients, have reported the highest discharge to home rate, 57%; over 70% were eventually discharged to home after first being transferred to a rehabilitation unit. On the other hand, the few reports of survival 1 or more years after discharge are in the 50% range at best (Table 2). Carson and colleagues [9] report a 23% 1-year survival in 133 PMV patients. Their premorbid functional status and age analysis showed younger and more independent patients having a better mortality (56%), and older and more dependent patients having a 95% mortality at 1 year. Nasraway et al [25] report a 1-year mortality of 50.5% in 97 patients transferred from five ICUs to multiple ECFs. Most of these patients would probably meet criteria for PMV, with median time mechanically ventilated 33 days, and 71 ventilator dependent at the time of ICU discharge. A report from 25 Vencor Hospitals [134] not included in Table 2 because weaning outcome was not reported, examines mortality and cost in patients > 65 years of age primarily referred for failure to wean from mechanical ventilation (91% of the cohort of 1619 patients.) There was a 58% in-hospital mortality by day 102 (28 days in the acute care hospital before referral, 74 days in the LTAC afterward), and a 67% mortality in postdischarge follow-up to day 180. Results of functional status studies and quality-of-life (QQL) measures, some using validated instruments, are now being reported in small series of PMV patients. These will merit consideration as important as weaning outcome, disposition, and survival data, as they accumulate to round out the treatment results in this population. Using a proprietary instrument, Carson et al [9] found 42% of 1-year survivors, that is, 8% of study patients, functionally independent at 1 year after discharge. Nasraway [25], using a single-question QQL assessment, and a validated functionality measurement, found 11.5% of his original cohort at home, breathing independently, with a "fair or better" QOL and good physical functionality. In a preliminary report from Dr. Criner's VRU, objective physical improvement was demonstrated in rehabilitation after PMV, using a functional independence measure scale [89]. A full report from the same unit, using a Sickness Impact Profile score makes it clear that PMV had no independent adverse effect on QOL several years later [135]. The 46 patients (25 of whom, with mean age 59 years, responded to the follow-up questionnaire), followed for 24 months after the catastrophic episode, scored their QOL based on their underlying chronic diseases, if any. The older patients, status postsurgical illness, predominantly cardiac surgery, rated their QOL better than younger patients with acute or chronic diseases. Similar findings have been reported in a recent ICU study, reporting QOL after prolonged intensive care [136]. Those who work to liberate PMV patients from mechanical ventilation, a satisfying end in many ways, have demonstrated that this post-ICU critical care activity is usually safe, and successful, although only in observational studies. Will multicenter studies in PMV patients liberated from mechanical ventilation yield facility benchmark, weaning outcome, and survival data that warrant continuation of these activities on a cost-per-outcome basis? That remains to be seen. Assessing and interpreting QOL and functionality findings in these patients, many with underlying chronic diseases resulting in long convalescence and rehabilitation, is a particularly important challenge. The authors are participating in a multicenter study that will yield some of these data; no doubt others will also address these questions. In the mean time, "No one in our society is willing to put Grandma out on an iceberg because she's no longer contributing. Someone needs to take care of these people" [137].

New treatment of acute hypoxemic respiratory failure: noninvasive pressure support ventilation delivered by helmet--a pilot controlled trial

OBJECTIVE

To assess the efficacy of noninvasive pressure support ventilation (NPSV) using a new special helmet as first-line intervention to treat patients with hypoxemic acute respiratory failure (ARF), in comparison to NPSV using standard facial mask.

DESIGN AND SETTING

Prospective clinical pilot investigation with matched control group in three intensive care units of university hospitals.

PATIENTS AND METHODS

Thirty-three consecutive patients without chronic obstructive pulmonary disease and with hypoxemic ARF (defined as severe dyspnea at rest, respiratory rate >30 breaths/min, PaO2:FiO2 < 200, and active contraction of the accessory muscles of respiration) were enrolled. Each patient treated with NPSV by helmet was matched with two controls with ARF treated with NPSV via a facial mask, selected by simplified acute physiologic score II, age, PaO2/FiO2, and arterial pH at admission. Primary end points were the improvement of gas exchanges, the need for endotracheal intubation, and the complications related to NPSV.

RESULTS

The 33 patients and the 66 controls had similar characteristics at baseline. Both groups improved oxygenation after NPSV. Eight patients (24%) in the helmet group and 21 patients (32%) in the facial mask group (p = .3) failed NPSV and were intubated. No patients failed NPSV because of intolerance of the technique in the helmet group in comparison with 8 patients (38%) in the mask group (p = .047). Complications related to the technique (skin necrosis, gastric distension, and eye irritation) were fewer in the helmet group compared with the mask group (no patients vs. 14 patients (21%), p = .002). The helmet allowed the continuous application of NPSV for a longer period of time (p = .05). Length of stay in the intensive care unit, intensive care, and hospital mortality were not different.

CONCLUSIONS

NPSV by helmet successfully treated hypoxemic ARF, with better tolerance and fewer complications than facial mask NPSV.

Translaryngeal open ventilation to treat acute respiratory failure in acute exacerbation of chronic obstructive pulmonary disease. A preliminary report

PURPOSE

To describe a minimally invasive alternative to conventional mechanical ventilation, using a small size uncuffed nasotracheal tube (translaryngeal open ventilation) paired with pressure control ventilation, in acute respiratory failure complicating chronic obstructive pulmonary disease (COPD).

CLINICAL FEATURES

Two cooperative COPD patients, who failed noninvasive mechanical ventilation, were intubated nasotracheally. Mechanical ventilation was initiated in pressure control mode via an uncuffed 6 mm tube.

RESULTS

Respiratory rate improved after 1 hour (from 44 to 28 breaths*min(-1) in case 1 and from 32 to 25 breaths*min(-1) in case 2); PaC0(2) decreased (from 120 to 62 mmHg in case 1 and from 69 to 51 mmHg in case 2); with pressure control mode levels of 45 cm H(2)O and 55 cm H(2)O respectively. PaO(2) increased from 40 mmHg (with FIO(2) 0.3) to 55 mmHg (with FIO(2) 0.3) in the first patient and from 55 mmHg (with FIO(2) 0.4) to 60 mmHg (with FIO(2) 0.4 ) in the second patient; pH improved from 7.18 to 7.31 in case 1 and from 7.22 to 7.39 in case 2. Patients were able to trigger the ventilator, speak, swallow and to clear secretions spontaneously. Both patients were ventilated for three days in this manner without any adverse effects. Both survived and were discharged home after 20 and 18 days in hospital respectively.

CONCLUSION

This very preliminary report suggests that, in carefully selected patients who fail mask ventilation, mechanical support with translaryngeal open ventilation can improve gas exchange, breathing pattern and tachypnea, without hindering glottic function.

Ventilação não-invasiva com pressão positiva em pacientes com insuficiência respiratória aguda: fatores associados à falha ou ao sucesso

Objetivo: Determinar a eficiência da ventilação não-invasiva com pressão positiva (VNIPP) na insuficiência respiratória aguda e identificar fatores associados ao sucesso ou falha. Pacientes e métodos: Estudo aberto e prospectivo analisando 60 episódios de uso de VNIPP em 53 pacientes em insuficiência respiratória. Resultados: Em 37 episódios (62%) obteve-se sucesso sem intubação (grupo Sucesso, GS), enquanto em 23 ocasiões (38%) os pacientes foram intubados (grupo Falha, GF). Os pacientes do GF apresentaram escore de Apache II mais elevado do que os do GS (30,4 ± 9 versus 22,2 ± 8, p = 0,001). Após 2h de VNIPP houve redução da freqüência respiratória, sendo menos intensa no GF (de 33 ± 9 para 30 ± 8irpm, p = 0,094) do que no GS (de 39 ± 11 para 28 ± 9irpm, p < 0,001). Houve aumento da PaO2 (de 62 ± 22 para 101 ± 65mmHg, p < 0,001), sem diferenças entre os grupos. Nos pacientes com hipercapnia houve redução da PaCO2 no GS (de 76 ± 20 para 68 ± 21mmHg, p = 0,032) e não no GF (de 89 ± 23 para 93 ± 40mmHg, p = 0,54). O pH se elevou de 7,25 ± 0,10 e 7,34 ± 0,11, p = 0,007 no GS, mas não no GF (7,24 ± 0,07 e 7,21 ± 0,12, p = 0,48). A VNIPP foi utilizada por mais tempo no GS (3,4 ± 2,5 versus 2,3 ± 2 dias, p = 0,003) e com níveis mais altos de pressão respiratória positiva em via aérea (IPAP) (13,2 ± 3 versus 11 ± 4cmH2O, p = 0,02). Dez pacientes (17%) foram a óbito, todos no GF. A complicação mais freqüente foi lesão de pele no ponto de contato da máscara com o nariz (5, 8%). A VNIPP foi eficiente no tratamento da insuficiência respiratória aguda em cerca de 2/3 das vezes. Pacientes mais graves, menor eficiência em reduzir a freqüência respiratória, em reverter a acidose respiratória e o uso de níveis relativamente mais baixos de pressão respiratória positiva em via aérea (IPAP) associaram-se à falha. A alta mortalidade (10, 43%) nos casos de falha justifica esforços para otimizar sua utilização e ao mesmo tempo para reconhecer precocemente suas falhas, evitando-se protelar a intubação traqueal.

Noninvasive ventilation reduces mortality in acute respiratory failure following lung resection

When treated with invasive endotracheal mechanical ventilation (ETMV), acute respiratory insufficiency after lung resection is fatal in up to 80% of cases. Noninvasive positive-pressure ventilation (NPPV) may reduce the need for ETMV, thereby improving survival. We conducted a randomized prospective trial to compare standard therapy with and without nasal-mask NPPV in patients with acute hypoxemic respiratory insufficiency after lung resection. The primary outcome variable was the need for ETMV and the secondary outcome variables were in-hospital and 120-d mortality rates, duration of stay in the intensive care unit, and duration of in-hospital stay. Twelve of the 24 patients (50%) randomly assigned to the no-NPPV group required ETMV, versus only five of the 24 patients (20.8%) in the NPPV group (p = 0.035). Nine patients in the no-NPPV group died (37.5%), and three (12.5 %) patients in the NPPV group died (p = 0.045). The other secondary outcomes were similar in the two groups. NPPV is safe and effective in reducing the need for ETMV and improving survival after lung resection.

Pressure support noninvasive positive pressure ventilation treatment of acute cardiogenic pulmonary edema

We assessed cardiogenic pulmonary edema (CPE) patient response to full mask pressure support noninvasive positive pressure ventilation (NPPV). Adult patients presenting to the emergency department (ED) in acute respiratory failure who clinically required endotracheal intubation (ETI) were studied. In addition to routine therapy consisting of oxygen, nitrates, and diuretics, patients were started on full mask NPPV using a Puritan Bennett 7200 ventilator delivering pressure support 10 cm H(2)O, PEEP 5 cm H(2)O, FiO(2) 100%. Pressure support was titrated to achieve tidal volumes of 5 to 7 mL/kg, and PEEP titrated to achieve oxygen saturation (SaO(2)) > 90%. Outcome measures included arterial blood gas (ABG), Borg dyspnea score, vital signs, and need for ETI. Twenty patients mean age 74.7 +/- 14.3 years were entered on the study. Initial mean values on FiO(2) 100% by nonrebreather mask: pH 7.17 +/-.13, paCO(2) 65.5 +/- 19.4 mmHg, paO(2) 73.8 +/- 27.3 mm Hg, SaO(2) 89.7 +/- 10.0%, Borg score 8.1 +/- 1.4, and respiratory rate(RR) 38 +/- 6.3. At 60 minutes of NPPV, improvement was statistically significant: pH 7.28 (difference.11; 95% CI.04-.19), paCO(2) 45 (difference 20.5; 95% CI 8-33), Borg score 4.1 (difference 4.0; 95% CI 3-5), and RR 28.2 (difference 9.8; 95% CI 5-14). NPPV duration ranged from 30 minutes to 36 hours (median 2 hours, 45 minutes). Eighteen patients (90%) improved allowing cessation of NPPV. Two patients with concomitant severe chronic obstructive pulmonary disease (COPD) required ETI. There were no complications of NPPV. NPPV using full face mask and pressure support provided by a conventional volume ventilator is an effective treatment for CPE and may help prevent ETI.

Pediatric noninvasive positive pressure ventilation

OBJECTIVE: To review the clinical use of noninvasive positive pressure ventilation (NPPV) in both acute hypoxic and hypercarbic forms of pediatric respiratory failure, including its mechanism of action and implementation. DATA SOURCES: Studies were identified through a MEDLINE search using respiratory failure, pediatrics, noninvasive ventilation, and mechanical ventilation as key words. STUDY SELECTION: All original studies, including case reports, relating to the use of noninvasive positive pressure in pediatric respiratory failure were included. Because of the paucity of published literature on pediatric NPPV, no study was excluded. DATA EXTRACTION: Study design, numbers and diagnoses of patients, types of noninvasive ventilator, ventilator modes, outcome measures, and complications were extracted and compiled. DATA SYNTHESIS: For acute hypoxic respiratory failure, all the studies reported improvement in oxygenation indices and avoidance of endotracheal intubation. The average duration of NPPV therapy before noticeable clinical improvement was 3 hrs in most studies, and NPPV was applied continuously for 72 hrs before resolution of acute respiratory distress. In patients with acute hypercarbic respiratory failure, application of NPPV resulted in reduction of work of breathing, reduction in CO(2) tension, and increased serum bicarbonate and pH. These patients are older than patients in the acute hypoxic respiratory failure group and, in addition to improved blood gas indices, they reported improvement in subjective symptoms of dyspnea. Improvement in gas exchange abnormalities and subjective symptoms occurred within the same time span (the first 3 hrs) as in the acute hypoxic respiratory failure group. However, use of noninvasive techniques in patients with acute hypercarbic respiratory failure continued after resolution of acute symptoms. Complications related to protracted use of NPPV were common in this group. CONCLUSIONS: NPPV has limited benefits in a group of carefully selected pediatric patients with acute hypoxic and hypercarbic forms of respiratory failure. The routine use of this technique in pediatric respiratory failure needs to be studied in randomized controlled trials and better-defined patient subsets.

Non-invasive positive pressure ventilation for exacerbation of chronic obstructive pulmonary patients in the emergency department

Patients with acute exacerbation of chronic obstructive pulmonary disease (COPD) commonly present to the emergency department for treatment. Some of them, despite appropriate therapy become more dyspnoeic with increasing acute respiratory failure. The requirement for intubation and mechanical ventilation is for these patients often associated with a prolonged and complicated intensive care unit stay and has been associated with morbidity and mortality rates in excess. Non-invasive ventilation (NIV) emerged recently as a means of reducing those complications. NIV can be a safe and effective means of augmenting ventilation and decreasing inspiratory work in many patients with acute exacerbation of COPD. NIV is generally started in the intensive care unit. Except for a few negative studies, the overall compending studies seem to be in favour of the utilization of NIV in cases of exacerbation of COPD patients. There are few published data on the question whether NIV could or should be started earlier and initiated in the emergency department. It seems that NIV treatment could be an effective addition to standard treatment especially for acute exacerbation of COPD. A more extensive and routine use of non-invasive ventilation in the emergency department requires further study.

Techniques to avoid intubation: noninvasive positive pressure ventilation and heliox therapy

NPPV is useful in decreasing the intubation rate in carefully selected patients with acute respiratory failure--particularly in patients with COPD. The results of some studies also suggest a survival benefit for use of NPPV with acute respiratory failure associated with COPD. Heliox therapy may be beneficial for selected patients with large airway obstruction or asthma. The use of heliox for other indications is unclear. Heliox may adversely affect the function of respiratory care equipment such as flow meters, ventilators, nebulizers, and pulmonary function monitors.

Non-invasive ventilation for frail elderly patients with acute respiratory failure

We describe 3 elderly patients with acute respiratory failure who received respiratory assistance with nasal bi-level positive airway pressure (BiPAP) on the ward. In these patients with poor prognostic factors, non-invasive positive pressure ventilation was preferred as a reasonable alternative to invasive ventilation; indeed, their admission to the intensive care unit for mechanical support was considered inappropriate. Despite the small number of patients and limited experience with the technique, BiPAP is discussed here as a possible treatment for severe respiratory failure when endotracheal ventilation is controversial, especially in frail patients 80 years of age or older, because invasive ventilation is associated with high mortality and morbidity in these patients. Two questions nevertheless need further evaluation in this setting, and are also addressed. The first is technical: can transient non-invasive breathing assistance be delivered on the ward? The second is ethical: is BiPAP a possible alternative when invasive ventilation is considered inappropriate?