Co-morbidity and acute decompensations of COPD requiring non-invasive positive-pressure ventilation

Noninvasive Ventilation and High-Flow Nasal Therapy Administration in Chronic Obstructive Pulmonary Disease Exacerbations

Noninvasive ventilation (NIV) is considered to be the standard of care for the management of acute hypercapnic respiratory failure in patients with chronic obstructive pulmonary disease exacerbation. It can be delivered safely in any dedicated setting, from emergency rooms to high dependency or intensive care units and wards. NIV helps improving dyspnea and gas exchange, reduces the need for endotracheal intubation, and morbidity and mortality rates. It is therefore recognized as the gold standard in this condition. High-flow nasal therapy helps improving ventilatory efficiency and reducing the work of breathing in patients with severe chronic obstructive pulmonary disease. Early studies indicate that some patients with acute hypercapnic respiratory failure can be managed with high-flow nasal therapy, but more information is needed before specific recommendations for this therapy can be made. Therefore, high-flow nasal therapy use should be individualized in each particular situation and institution, taking into account resources, and local and personal experience with all respiratory support therapies.

Ventilator Support and Oxygen Therapy in Palliative and End-of-Life Care in the Elderly

Elderly patients suffering from chronic cardio-pulmonary diseases commonly experience acute respiratory failure. As in younger patients, a well-known therapeutic approach of noninvasive mechanical ventilation is able to prevent orotracheal intubation in a large number of severe scenarios in elderly patients. In addition, this type of ventilation is frequently applied in elderly patients who refuse intubation for invasive mechanical ventilation. The rate of failure of noninvasive ventilation may be reduced by means of the integration of new technological devices (i.e., high-flow nasal cannula, extracorporeal CO₂ removal, cough assistance and high-frequency chest wall oscillation, and fiberoptic bronchoscopy). Ethical issues with end-of-life decisions and the choice of the environment are not clearly defined in the treatment of elderly with acute respiratory insufficiency.

What Is the Impact of Mildly Altered Consciousness on Acute Hypoxemic Respiratory Failure with Non-invasive Ventilation?

Objective A severely altered level of consciousness (ALC) is considered to be a possible contraindication to non-invasive ventilation (NIV). We investigated the association between mild ALC and NIV failure in patients with hypoxemic respiratory failure. Methods A retrospective study was conducted by reviewing the medical charts of patients with de novo hypoxemic respiratory failure who received NIV treatment. The clinical background and the outcomes of patients with and without ALC were compared. Patients Patients who were admitted to our hospital for acute hypoxemic respiratory failure between July 2011 and May 2015 were included in the present study. Results Sixty-six of the 148 patients had ALC. In comparison to the patients without ALC, the patients with ALC were older (median: 72 vs. 78 years, p=0.02), had a higher Acute Physiology and Chronic Health Evaluation II score (18 vs. 19, p=0.02), and received a higher level of inspiratory pressure (8 cmH2O vs. 8, p<0.01). The median Glasgow Coma Scale score of the patients with ALC was 14 (interquartile range, 11-14). There were no significant differences between the groups in the rates of NIV failure (24% vs. 30%, p=0.4) and in-hospital mortality (13% vs. 16%, p=0.3). Conclusion NIV may be successfully applied to treat acute hypoxemic respiratory failure with mild ALC. NIV may be performed, with careful attention to the appropriate timing for intubation.

Comorbidities and Subgroups of Patients Surviving Severe Acute Hypercapnic Respiratory Failure in the Intensive Care Unit

RATIONALE

No methodical assessment of the lung, cardiac, and sleep function of patients surviving an acute hypercapnic respiratory failure episode requiring admission to the intensive care unit (ICU) has been reported in the literature.

OBJECTIVES

To prospectively investigate the prevalence and impact of comorbidities in patients treated by mechanical ventilator support (invasive or noninvasive) for acute hypercapnic respiratory failure in the ICU.

METHODS

Seventy-eight consecutive patients admitted for an episode of acute hypercapnic respiratory failure underwent an assessment of lung, cardiac, and sleep function by pulmonary function tests, transthoracic echocardiography, and polysomnography 3 months after ICU discharge.

MEASUREMENTS AND MAIN RESULTS

Sixty-seven percent (52 of 78) of patients exhibited chronic obstructive pulmonary disease (COPD), although only 19 had been previously diagnosed. Patients without COPD were primarily obese. Prevalence of severe obstructive sleep apnea was 51% (95% confidence interval, 34-69) in patients with COPD and 81% (95% confidence interval, 54-96) in patients without COPD. Previously undiagnosed cardiac dysfunction with preserved ejection fraction was highly prevalent (44%), as was hypertension (67%). More than half of the population demonstrated at least three major comorbidities known to precipitate acute hypercapnic respiratory failure. Multimorbidity was associated with longer time to hospital discharge. Hospital readmission or death occurred in 46% of patients over an average of 3.5 months after discharge.

CONCLUSIONS

Severe hypercapnic respiratory failure requiring ICU admission resulted primarily from COPD or obesity. Major comorbidities are highly prevalent in both cases and most often ignored. Surviving acute hypercapnic respiratory failure should be an opportunity to systematically evaluate lung, heart, and sleep functions to improve poor outcomes. Clinical trial registered with www.clinicaltrials.gov (NCT 02111876).

Challenges on non-invasive ventilation to treat acute respiratory failure in the elderly

Acute respiratory failure is a frequent complication in elderly patients especially if suffering from chronic cardio-pulmonary diseases. Non-invasive mechanical ventilation constitutes a successful therapeutic tool in the elderly as, like in younger patients, it is able to prevent endotracheal intubation in a wide range of acute conditions; moreover, this ventilator technique is largely applied in the elderly in whom invasive mechanical ventilation is considered not appropriated. Furthermore, the integration of new technological devices, ethical issues and environment of treatment are still largely debated in the treatment of acute respiratory failure in the elderly.

This review aims at reporting and critically analyzing the peculiarities in the management of acute respiratory failure in elderly people, the role of noninvasive mechanical ventilation, the potential advantages of applying alternative or integrated therapeutic tools (i.e. high-flow nasal cannula oxygen therapy, non-invasive and invasive cough assist devices and low-flow carbon-dioxide extracorporeal systems), drawbacks in physician’s communication and “end of life” decisions. As several areas of this topic are not supported by evidence-based data, this report takes in account also “real-life” data as well as author’s experience.

The choice of the setting and of the timing of non-invasive mechanical ventilation in elderly people with advanced cardiopulmonary disease should be carefully evaluated together with the chance of using integrated or alternative supportive devices. Last but not least, economic and ethical issues may often challenges the behavior of the physicians towards elderly people who are hospitalized for acute respiratory failure at the end stage of their cardiopulmonary and neoplastic diseases.

Early failure of noninvasive ventilation in chronic obstructive pulmonary disease with acute hypercapnic respiratory failure

Noninvasive ventilation (NIV) in the management of chronic obstructive pulmonary disease (COPD) patients with acute hypercapnic respiratory failure is considered a first-line therapy. However, patients who fail NIV and then require invasive mechanical ventilation have been found to have higher mortality than patients initially treated with invasive mechanical ventilation. We tried to find parameters associated with early NIV failure (need for intubation or death <24 h of starting NIV) in patients presenting to the ED with acute exacerbation of COPD. A retrospective analysis was conducted of the medical records of 218 patients with acute exacerbation of COPD visiting Asan Medical Center and managed with NIV during their stay in the ED from January 2007 to December 2013. NIV was successful in 200 (91.7%) and 18 (8.3%) had early NIV failure. Of the variables obtained before NIV treatment, heart rate (≥120/min: OR 2.5, 95% CI 1.2-7.0) and pH (7.25-7.29: OR 2.1, 95% CI 1.0-8.8; <7.25: OR 11.7, 95% CI 3.5-38.6) were significant factors associated with early NIV failure. Of the variables obtained after 1 h of NIV treatment, heart rate (≥120/min: OR 7.5, 95% CI 2.3-24.3) and pH (7.25-7.29: OR 4.7, 95% CI 1.5-15.1; <7.25: OR 20.9, 95% CI 5.4-61.2) were still significant. The presence of tachycardia and severe acidosis before NIV treatment and persistence of tachycardia and severe acidosis after 1 h of NIV treatment were associated with early NIV failure.

Nutritional Risk Screening 2002 as a Predictor of Outcome During General Ward-Based Noninvasive Ventilation in Chronic Obstructive Pulmonary Disease with Respiratory Failure

BACKGROUND Noninvasive ventilation (NIV) may reduce the need for intubation and mortality associated with chronic obstructive pulmonary disease (COPD) with type II respiratory failure. Early and simple predictors of NIV outcome could improve clinical management. This study aimed to assess whether nutritional risk screening 2002 (NRS2002) is a useful outcome predictor in COPD patients with type II respiratory failure treated by noninvasive positive pressure ventilation (NIPPV). MATERIAL AND METHODS This prospective observational study enrolled COPD patients with type II respiratory failure who accepted NIPPV. Patients were submitted to NRS2002 evaluation upon admission. Biochemical tests were performed the next day and blood gas analysis was carried out prior to NIPPV treatment and 4 hours thereafter. Patients were divided into NRS2002 score ≥3 and NRS2002 score <3 groups and NIV failure rates were compared between both groups. RESULTS Of the 233 patients, 71 (30.5%) were not successfully treated by NIPPV. The failure rate was significantly higher in the NRS2002 score ≥3 group (35.23%) in comparison with patients with NRS2002 score <3 (15.79%) (p<0.05). Multivariate analysis indicated that PaCO2 (OR 1.25, 95%CI 1.172-1.671, p<0.05) prior to NIPPV treatment and NRS2002 score ≥3 (OR 1.76, 95%CI 1.303-2.374, p<0.05) were independent predictive factors for NIPPV treatment failure. CONCLUSIONS NRS2002 score ≥3 and PaCO2 values at admission may predict unsuccessful NIPPV treatment of COPD patients with type II respiratory failure and help to adjust therapeutic strategies. NRS2002 is a noninvasive and simple method for predicting NIPPV treatment outcome.

Measurement of activities of daily living in patients with COPD: a systematic review

BACKGROUND

The objectives of this systematic review were to synthesize the literature on measures of activities of daily living (ADLs) that have been used in individuals with COPD and to provide an overview of the psychometric properties of the identified measures and describe the relationship of the disease-specific instruments with other relevant outcome measures for individuals with COPD and health-care use.

METHODS

Studies that included a measure of ADLs in individuals with COPD were identified using electronic and hand searches. Two investigators performed the literature search. One investigator reviewed the study title, abstract, and full text of the articles to determine study eligibility and performed the data extraction and tabulation. In cases of uncertainty, a second reviewer was consulted.

RESULTS

A total of 679 articles were identified. Of those, 116 met the inclusion criteria. Twenty-seven ADLs instruments were identified, of which 11 instruments were respiratory disease-specific, whereas 16 were generic. Most instruments combined instrumental ADLs (IADLs) with basic ADLs (BADLs). The majority of the instruments were self-reported; only three instruments were performance based. Twenty-one studies assessed psychometric properties of 16 ADLs instruments in patients with COPD.

CONCLUSIONS

Although several ADLs instruments were identified, psychometric properties have only been reported in a few. Selection of the most appropriate measure should focus on the target construct (BADLs or IADLs or both), type of test (disease-specific vs generic and self-reported vs performance-based), depth of information obtained, and psychometric properties of the instruments. Given the relevance of ADLs to the lives of patients with COPD, its assessment should be more frequently incorporated as a clinical outcome in their management.

Clinical characteristics associated with adverse events in patients with exacerbation of chronic obstructive pulmonary disease: a prospective cohort study

BACKGROUND

To assist physicians with difficult decisions about hospital admission for patients with acute exacerbation of chronic obstructive pulmonary disease (COPD) presenting in the emergency department, we sought to identify clinical characteristics associated with serious adverse events.

METHODS

We conducted this prospective cohort study in 6 large Canadian academic emergency departments. Patients were assessed for standardized clinical variables and then followed for serious adverse events, defined as death, intubation, admission to a monitored unit or new visit to the emergency department requiring admission.

RESULTS

We enrolled 945 patients, of whom 354 (37.5%) were admitted to hospital. Of 74 (7.8%) patients with a subsequent serious adverse event, 36 (49%) had not been admitted after the initial emergency visit. Multivariable modelling identified 5 variables that were independently associated with adverse events: prior intubation, initial heart rate ≥ 110/minute, being too ill to do a walk test, hemoglobin < 100 g/L and urea ≥ 12 mmol/L. A preliminary risk scale incorporating these and 5 other clinical variables produced risk categories ranging from 2.2% for a score of 0 to 91.4% for a score of 10. Using a risk score of 2 or higher as a threshold for admission would capture all patients with a predicted risk of adverse events of 7.2% or higher, while only slightly increasing admission rates, from 37.5% to 43.2%.

INTERPRETATION

In Canada, many patients with COPD suffer a serious adverse event or death after being discharged home from the emergency department. We identified high-risk characteristics and developed a preliminary risk scale that, once validated, could be used to stratify the likelihood of poor outcomes and to enable rational and safe admission decisions.

Timing of noninvasive ventilation failure: causes, risk factors, and potential remedies

Background

Identifying the predictors of noninvasive ventilation (NIV) failure has attracted significant interest because of the strong link between failure and poor outcomes. However, very little attention has been paid to the timing of the failure. This narrative review focuses on the causes of NIV failure and risk factors and potential remedies for NIV failure, based on the timing factor.

Results

The possible causes of immediate failure (within minutes to <1 h) are a weak cough reflex, excessive secretions, hypercapnic encephalopathy, intolerance, agitation, and patient-ventilator asynchrony. The major potential interventions include chest physiotherapeutic techniques, early fiberoptic bronchoscopy, changing ventilator settings, and judicious sedation. The risk factors for early failure (within 1 to 48 h) may differ for hypercapnic and hypoxemic respiratory failure. However, most cases of early failure are due to poor arterial blood gas (ABGs) and an inability to promptly correct them, increased severity of illness, and the persistence of a high respiratory rate. Despite a satisfactory initial response, late failure (48 h after NIV) can occur and may be related to sleep disturbance.

Conclusions

Every clinician dealing with NIV should be aware of these risk factors and the predicted parameters of NIV failure that may change during the application of NIV. Close monitoring is required to detect early and late signs of deterioration, thereby preventing unavoidable delays in intubation.

Determinants of noninvasive ventilation outcomes during an episode of acute hypercapnic respiratory failure in chronic obstructive pulmonary disease: the effects of comorbidities and causes of respiratory failure

Objectives. To investigate the effect of the cause of acute respiratory failure and the role of comorbidities both acute and chronic on the outcome of COPD patients admitted to Respiratory Intensive Care Unit (RICU) with acute respiratory failure and treated with NIV. Design. Observational prospective study. Patients and Methods. 176 COPD patients consecutively admitted to our RICU over a period of 3 years and treated with NIV were evaluated. In all patients demographic, clinical, and functional parameters were recorded including the cause of acute respiratory failure, SAPS II score, Charlson comorbidity index, and further comorbidities not listed in the Charlson index. NIV success was defined as clinical improvement leading to discharge to regular ward, while exitus or need for endotracheal intubation was considered failure. Results. NIV outcome was successful in 134 patients while 42 underwent failure. Univariate analysis showed significantly higher SAP II score, Charlson index, prevalence of pneumonia, and lower serum albumin level in the failure group. Multivariate analysis confirmed a significant predictive value for pneumonia and albumin. Conclusions. The most important determinants of NIV outcome in COPD patients are the presence of pneumonia and the level of serum albumin as an indicator of the patient nutritional status.

[Evidence-based medicine: implications from the guideline "non-invasive ventilation" in critically ill elderly patients]

The demographic shift means that there are an increasing number of elderly critically ill patients with various comorbidities. This very specific group needs particular treatment which has not been considered sufficiently in medical guidelines so far. To improve health care, it is indispensable not only to work out the current guidelines, but aspects of geriatric medicine must also be integrated into future developments. Using the example of the recent guideline "non-invasive ventilation," it is shown how the process of designing and implication can actively be realized in clinical daily routine.

Hypercapnic encephalopathy syndrome: a new frontier for non-invasive ventilation?

According to the classical international guidelines, non-invasive ventilation is contraindicated in hypercapnic encephalopathy syndrome (HES) due to the poor compliance to ventilatory treatment of confused/agitated patients and the risk of aspirative pneumonia related to lack of airways protection. As a matter of fact, conventional mechanical ventilation has been recommended as "golden standard" in these patients. However, up to now there are not controlled data that have demonstrated in HES the advantage of conventional mechanical ventilation vs non-invasive ventilation. In fact, patients with altered mental status have been systematically excluded from the randomised and controlled trials performed with non-invasive ventilation in hypercapnic acute respiratory failure. Recent studies have clearly demonstrated that an initial cautious NPPV trial in selected HES patients may be attempt as long as there are no other contraindications and the technique is provided by experienced caregivers in a closely monitored setting where ETI is always readily available. The purpose of this review is to report the physiologic rationale, the clinical feasibility and the still open questions about the careful use of non-invasive ventilation in HES as first-line ventilatory strategy in place of conventional mechanical ventilation via endotracheal intubation.

COPD exacerbation: mortality prognosis factors in a respiratory care unit

OBJECTIVE

The aim of our study was to investigate the mortality predictive factors after a severe exacerbations of COPD admitted to a Spanish respiratory intermediate care unit (IRCU).

PATIENTS AND METHODS

Prospective observational 2 years study, where we included all episodes of acute exacerbations of COPD with hypercapnic respiratory failure admitted in an IRCU. We analyzed different sociodemographic, functional and clinical variables including physical activity.

RESULTS

We collected data from 102 consecutive episodes admitted to IRCU (90.1% men). Mean age was 69.4±10.6. The mean APACHE II was 19.6±5.0 and 9.5% presented a failure of other non respiratory organ. Non invasive ventilation was applied in 75.3% of the episodes and this treatment failed in 11.6% of them. The duration of stay in the IRCU was 3.5±2.1 days and 8.0±5.3 days in the hospital. The hospital mortality rate was 6.9%, and another 12.7% after 90 days of discharged. In order to predict hospital mortality, multivariant statistics identified a model with AUC of 0.867, based in 3 variables: the number of previous year admission for COPD exacerbation (p=0,048), the respiratory rate after 2 hours of treatment in the IRCU (p=0.0484) and the severity of the disease established with ADO score (p=0.0241).

CONCLUSIONS

The number of previous year admission for COPD exacerbation, the severity of the disease established with ADO score, the respiratory rate after 2 hours of treatment, allow us to identify what patients with a COPD exacerbation admitted in a IRCU can die during this episode.

Use of noninvasive ventilation on internal wards for elderly patients with limitations to respiratory care: a cohort study

BACKGROUND

The use of noninvasive positive pressure ventilation (NPPV) outside the intensive wards has been evaluated in patients with no limitation on life-sustaining support. Our aim was to evaluate its usefulness in general wards for patients with NPPV as the ceiling of ventilator care when admission to the intensive care unit (ICU) has been withheld.

MATERIALS AND METHODS

Noninvasive positive pressure ventilation was used in 44 patients with acute respiratory failure (ARF) and limitations to respiratory care- 22 with chronic obstructive pulmonary disease (COPD) exacerbations and 22 with acute cardiogenic pulmonary oedema (CPE). Survival at hospital discharge, and survival and readmission rate at 12 months were assessed.

RESULTS

Sixty-three per cent of COPD and 55% of CPE patients survived hospital discharge; and 50% and 37% respectively, were alive after 1 year. The cause of the in-hospital mortality was related to the admission diagnosis in 88% of cases. Cancer in COPD patients [P = 0·040, odds ratio (OR) = 15, 95% CI = 1·14-198] and the completion of NPPV treatment in both diseases (P = 0·008, OR = 0·03, 95% CI = 0·00-0·39 for COPD and P = 0·010, OR = 0·04, 95% CI = 0·00-0·45 for CPE) were related to in-hospital mortality. Fifty-six per cent of COPD and 33% of CPE patients that survived hospital admission were readmitted.

CONCLUSIONS

Our study suggests that the use of NPPV in general wards could be a safe and effective option, as a last choice treatment, in patients with NPPV as the ceiling of ventilator care when admission to ICU has been withheld.

Predicting outcomes following hospitalization for acute exacerbations of COPD

Acute exacerbations of chronic obstructive pulmonary disease (AECOPD) are a frequent cause of hospital admission and are associated with significant morbidity, mortality, high readmission rates and high resource utilization. More accurate prediction of survival and readmission in patients hospitalized with AECOPD should help to optimize clinical management and allocation of resources, including targeting of palliative care and strategies to reduce readmissions. We have reviewed the published retrospective and prospective studies in this field to identify the factors most likely to be of value in predicting in-hospital and post-discharge mortality, and readmission of patients hospitalized for AECOPD. The prognostic factors which appear most important vary with the particular outcome under consideration. In-hospital mortality is related most clearly to the patient's acute physiological state and to the development of acute comorbidity, while post-discharge mortality particularly reflects the severity of the underlying COPD, as well as specific comorbidities, especially cardiac disease. Important factors influencing the frequency of readmission include functional limitation and poor health-related quality of life. Large prospective studies which incorporate all the potentially relevant variables are required to refine prediction of the important outcomes of AECOPD and thus to inform clinical decision making, for example on escalation of care, facilitated discharge and provision of palliative care.

Noninvasive ventilation for acute respiratory failure after lung resection: an observational study

BACKGROUND

A single prospective randomized study found that, in selected patients with acute respiratory failure (ARF) following lung resection, noninvasive ventilation (NIV) decreases the need for endotracheal mechanical ventilation and improves clinical outcome.

METHOD

We prospectively evaluated early NIV use for ARF after lung resection during a 4-year period in the setting of a medical and a surgical ICU of a university hospital. We documented demographics, initial clinical characteristics and clinical outcomes. NIV failure was defined as the need for tracheal intubation.

RESULTS

Among 690 patients at risk of severe complications following lung resection, 113 (16.3%) experienced ARF, which was initially supported by NIV in 89 (78.7%), including 59 with hypoxemic ARF (66.3%) and 30 with hypercapnic ARF (33.7%). The overall success rate of NIV was 85.3% (76/89). In-ICU mortality was 6.7% (6/89). The mortality rate following NIV failure was 46.1%. Predictive factors of NIV failure in univariate analysis were age (P = 0.046), previous cardiac comorbidities (P = 0.0075), postoperative pneumonia (P = 0.0016), admission in the surgical ICU (P = 0.034), no initial response to NIV (P < 0.0001) and occurrence of noninfectious complications (P = 0.037). Only two independent factors were significantly associated with NIV failure in multivariate analysis: cardiac comorbidities (odds ratio, 11.5; 95% confidence interval, 1.9-68.3; P = 0.007) and no initial response to NIV (odds ratio, 117.6; 95% confidence interval, 10.6-1305.8; P = 0.0001).

CONCLUSION

This prospective survey confirms the feasibility and efficacy of NIV in ARF following lung resection.

Evolution of Patients With Chronic Obstructive Pulmonary Disease, Obesity Hypoventilation Syndrome, or Congestive Heart Failure Undergoing Noninvasive Ventilation in a Respiratory Monitoring Unit

OBJECTIVE

We compared the use of noninvasive ventilation (NIV) for hypercapnic acidosis with hypoxemia in patients with chronic obstructive pulmonary disease (COPD), obesity hypoventilation syndrome (OHS), or congestive heart failure (CHF) in a respiratory medicine monitoring unit. The objective was to evaluate each diagnostic groups response to therapy in terms of clinical course and evolution of blood gases.

PATIENTS AND METHODS

Prospective, 12-month study of 53 patients with hypercapnic acidosis with hypoxemia. Twenty-seven patients had COPD, 17 OHS, and 9 CHF. Severity was assessed based on initial arterial blood gas analysis. Clinical course was studied by blood gas analysis after conventional treatment and after NIV (1-3 hours and 12-24 hours). Mortality was recorded. All patients received bilevel positive airway pressure support in assist-control mode.

RESULTS

No significant differences were observed between mean (SD) initial pH findings in the 3 diagnostic groups: COPD, 7.28 (0.1); OHS, 7.29 (0.09); and CHF, 7.24 (0.07). (nonsignificant differences). After initial conventional treatment, PaCO2 worsened for COPD patients (P = .026) and PaO2 improved for CHF patients (P = .028). After 1 to 3 hours of NIV, pH (P = .002) and PaO2 (P = .041) improved for COPD patients, and pH (P = .03) and PaCO2 (P = .045) improved in OHS patients; no significant changes were observed in CHF patients. After 12 to 24 hours of NIV, the mean pH was 7.36 (0.04) for COPD patients, 7.36 (0.05) for OHS patients, and 7.25 (0.1) for CHF patients (not significant). The mortality rate was 11.1% for COPD, 0% for OHS, and 33.3% for CHS (not significant, P = .076).

CONCLUSIONS

In this group of patients with similar initial arterial blood gas values, response to NIV was seen to be better in OHS and COPD than in CHF. That the start of NIV is usually preceded by a poor response to conventional COPD treatment suggests that delaying NIV should be reconsidered.

Noninvasive positive pressure ventilation in patients with acute exacerbations of COPD and varying levels of consciousness

STUDY OBJECTIVES

A severely altered level of consciousness (ALC) has been considered a contraindication to noninvasive positive pressure ventilation (NPPV). We compared the clinical outcome of patients with acute respiratory failure (ARF) due to COPD exacerbations and different degrees of ALC.

DESIGN

A 5-year case-control study with a prospective data collection.

SETTING

Respiratory Monitoring Unit.

PATIENTS

Eighty of 153 consecutive COPD patients requiring NPPV for ARF were divided into four groups, which were carefully matched for the main physiologic variables, according to the level of consciousness assessed with the Kelly-Matthay Score, in which 1 is normal (control subjects) and 6 is severely impaired.

MEASUREMENT AND RESULTS

Changes from baseline in arterial blood gas (ABG) levels and Kelly score, the rate and causes of NPPV failure, the rate of nosocomial pneumonia, and the 90-day mortality rate were compared. NPPV significantly improved ABG levels and Kelly score in all groups after 1 to 2 h. NPPV failure (Kelly score 1 = 15%; Kelly score 2 = 25%; Kelly score 3 = 30%; Kelly score > 3 = 45%) and 90-day mortality rate (Kelly score 1 = 20%; Kelly score 2 = 35%; Kelly score 3 = 35%; Kelly score > 3 = 50%) significantly increased with the worsening of the level of consciousness. Using a multivariate analysis, the acute nonrespiratory component of the acute physiology and chronic health evaluation (APACHE) III score, and baseline pH independently predicted baseline Kelly score. After 1 to 2 h of NPPV, changes in the Kelly score were associated with those in pH. No correlation was found with Pa(CO2).

CONCLUSIONS

This study confirms that NPPV may be successfully applied to patients experiencing COPD exacerbations with milder ALCs, whereas the rate of failure in patients with severely ALCs (ie, Kelly score > 3) is higher, even though better than expected, so that an initial and cautious attempt with NPPV may be performed even in this latter group. Changes in the level of consciousness induced by NPPV are not correlated with those in Pa(CO2).

Non-invasive ventilation for acute respiratory disease

Non-invasive ventilation (NIV) has been shown to be effective in acute respiratory failure of various aetiologies in different health care systems and ward settings. It should be seen as complementary to invasive ventilation and primarily a means of preventing some patients from deteriorating to the point at which intubation is needed. Generally it is best initiated early before assisted ventilation is mandatory, although it has been shown to be effective even in very sick patients. Important benefits include the avoidance of endotracheal-tube-associated infections, which carry an important morbidity and mortality, and a reduction in health care costs. The most important ingredient for an acute NIV service is a well-trained enthusiastic ward team.