Incidence and causes of non-invasive mechanical ventilation failure after initial success

Noninvasive Mechanical Ventilation in Acute Ventilatory Failure: Rationale and Current Applications

Noninvasive ventilation plays a pivotal role in acute ventilator failure and has been shown, in certain disease processes such as acute exacerbation of chronic obstructive pulmonary disease, to prevent and shorten the duration of invasive mechanical ventilation, reducing the risks and complications associated with it. The application of noninvasive ventilation is relatively simple and well tolerated by patients and in the right setting can change the course of their illness.

Predictors of high flow nasal cannula failure in immunocompromised patients with acute respiratory failure due to non-HIV pneumocystis pneumonia

Background

To evaluate the predictors of high flow nasal cannula (HFNC) failure in pneumocystis pneumonia (PCP) patients with acute respiratory failure (ARF).

Methods

Fifty-two non-HIV-related PCP subjects were divided into a HFNC success group (44%) and a HFNC failure group (who required mechanical ventilation (MV) despite HFNC application) (56%). The clinical characteristics and physiologic effects were retrospectively reviewed and compared between the groups.

Results

At baseline, the heart rate, alveolar-arterial PO₂ difference [P(A-a)O₂], Sequential Organ Failure Assessment (SOFA) score, and proportion of subjects who used vasopressors were significantly higher in the HFNC failure group than in the HFNC success group. The 60-day mortality was 52% in the HFNC failure group and 13% in the HFNC success group (P=0.004). The results of the multivariate analysis indicated that the baseline SOFA score was independently associated with HFNC failure (adjusted odds ratio, 1.74 per each score unit increase; 95% CI, 1.05-2.89; P=0.03). Repeated measures analysis of variance revealed that within 6 h of HFNC initiation, the mean PaO₂/FiO₂ ratio decreased and the mean P(A-a)O₂ increased rapidly in the HFNC failure group.

Conclusions

Patients with ARF due to PCP subjected to HFNC therapy should be carefully monitored, and particular attention should be paid to those who had organ dysfunction and did not show early oxygenation improvement.

Nasal high flow therapy: a novel treatment rather than a more expensive oxygen device

Nasal high flow is a promising novel oxygen delivery device, whose mechanisms of action offer some beneficial effects over conventional oxygen systems. The administration of a high flow of heated and humidified gas mixture promotes higher and more stable inspiratory oxygen fraction values, decreases anatomical dead space and generates a positive airway pressure that can reduce the work of breathing and enhance patient comfort and tolerance. Nasal high flow has been used as a prophylactic tool or as a treatment device mostly in patients with acute hypoxaemic respiratory failure, with the majority of studies showing positive results. Recently, its clinical indications have been expanded to post-extubated patients in intensive care or following surgery, for pre- and peri-oxygenation during intubation, during bronchoscopy, in immunocompromised patients and in patients with “do not intubate” status. In the present review, we differentiate studies that suggest an advantage (benefit) from other studies that do not suggest an advantage (no benefit) compared to conventional oxygen devices or noninvasive ventilation, and propose an algorithm in cases of nasal high flow application in patients with acute hypoxaemic respiratory failure of almost any cause.

Discontinuing noninvasive ventilation in severe chronic obstructive pulmonary disease exacerbations: a randomised controlled trial

We assessed whether prolongation of nocturnal noninvasive ventilation (NIV) after recovery from acute hypercapnic respiratory failure (AHRF) in chronic obstructive pulmonary disease (COPD) patients with NIV could prevent subsequent relapse of AHRF.A randomised controlled trial was performed in 120 COPD patients without previous domiciliary ventilation, admitted for AHRF and treated with NIV. When the episode was resolved and patients tolerated unassisted breathing for 4 h, they were randomly allocated to receive three additional nights of NIV (n=61) or direct NIV discontinuation (n=59). The primary outcome was relapse of AHRF within 8 days after NIV discontinuation.Except for a shorter median (interquartile range) intermediate respiratory care unit (IRCU) stay in the direct discontinuation group (4 (2-6) versus 5 (4-7) days, p=0.036), no differences were observed in relapse of AHRF after NIV discontinuation (10 (17%) versus 8 (13%) for the direct discontinuation and nocturnal NIV groups, respectively, p=0.56), long-term ventilator dependence, hospital stay, and 6-month hospital readmission or survival.Prolongation of nocturnal NIV after recovery from an AHRF episode does not prevent subsequent relapse of AHRF in COPD patients without previous domiciliary ventilation, and results in longer IRCU stay. Consequently, NIV can be directly discontinued when the episode is resolved and patients tolerate unassisted breathing.

Non invasive ventilation in patients with chronic obstructive pulmonary disease in a hospital and at home

Last two decades, active use of non-invasive ventilation (NIV) has provided a significant improvement in the management of chronic obstructive pulmonary disease (COPD), both in patients with acute exacerbation and in stable patients. Currently, NIV is the first-line treatment for patients with acute exacerbation of COPD and acute hypercapnic respiratory failure. This method of respiratory support is also effective after extubation, as it could facilitate weaning from the ventilator and affects positively prevention and treatment of postextubation respiratory failure. Also, NIV has been successfully used in co-morbidity of COPD and sleep apnea syndrome, COPD and pneumonia, and in early postoperative period after thoracic surgery. NIV can be used in COPD patients with chronic respiratory failure. Long-term NIV at home is more reasonable in patients with daytime hypercapnia. The most effective strategy of respiratory support in COPD is thought to be decrease in the partial pressure of carbon dioxide in the arterial blood, i.e. high-intensity NIV. Currently available portable non-invasive ventilators could improve significantly physical activity of patients with severe COPD.

Glycated hemoglobin A1c-based adjusted glycemic variables in patients with diabetes presenting with acute exacerbation of chronic obstructive pulmonary disease

Acute hyperglycemia is a common finding in patients presenting to emergency departments (EDs) with acute exacerbation of chronic obstructive pulmonary disease (AECOPD). Several studies have argued against the association between hyperglycemia at admission and adverse outcomes in patients with diabetes and an acute illness. Recent studies have shown that glucose-related variables (eg, glycemic gaps and stress hyperglycemia ratios) that are adjusted for glycated hemoglobin levels can indicate the severity of a variety of diseases. The objective of this study was to assess whether these hemoglobin A1c (HbA1c)-based adjusted average glycemic variables were associated with unfavorable outcomes in patients admitted to a hospital with AECOPD. We found that 1) pulmonary infection is a major risk factor for AECOPD; 2) a higher glycemic gap and modified stress hyperglycemia ratio were associated with the development of acute respiratory failure (ARF) in patients with diabetes admitted to an ED because of AECOPD; and 3) the glycemic gap and modified stress hyperglycemia ratio had superior discriminative power over acute hyperglycemia and HbA1c for predicting the development of ARF, although the HbA1c-adjusted glycemic variables alone were not independent risk factors for ARF.

Delayed but successful response to noninvasive ventilation in COPD patients with acute hypercapnic respiratory failure

Background

We evaluated a new noninvasive ventilation (NIV) protocol that allows the pursuit of NIV in the case of persistent severe respiratory acidosis despite a first NIV challenge in COPD patients with acute hypercapnic respiratory failure (AHRF).

Patients and methods

A prospective observational multicentric pilot study was conducted in three tertiary hospitals over a 12-month study period. A total of 155 consecutive COPD patients who were admitted for AHRF and treated by NIV were enrolled. Delayed response to NIV was defined as a significant clinical improvement in the first 48 h following NIV initiation despite a persistent severe respiratory acidosis (pH <7.30) after the first 2 h of NIV trial.

Results

NIV failed in only 10 patients (6.5%). Delayed responders to NIV (n=83, 53%) exhibited similar nutritional status, comorbidities, functional status, frailty score, dyspnea score, and severity score at admission, compared with early responders (n=62, 40%). Only age (66 vs 70 years in early responders; P=0.03) and encephalopathy score (3 [2–4] vs 3 [2–4] in early responders; P=0.015) were different among the responders. Inhospital mortality did not differ between responders to NIV (n=10, 12% for delayed responders vs n=10, 16% for early responders, P=0.49). A second episode of AHRF occurred in 20 responders (14%), equally distributed among early and delayed responders to NIV (n=9, 14.5% in early responders vs n=11, 13% in delayed responders; P=0.83), with a poor survival rate (n=1, 5%).

Conclusion

Most of the COPD patients with AHRF have a successful outcome when NIV is pursued despite a persistent severe respiratory acidosis after the first NIV trial. The outcome of delayed responders is similar to the one of the early responders. On the contrary, the second episode of AHRF during the hospital stay carries a poor prognosis.

Clinical management of chronic obstructive pulmonary disease patients with muscle dysfunction

Muscle dysfunction is frequently observed in chronic obstructive pulmonary disease (COPD) patients, contributing to their exercise limitation and a worsening prognosis. The main factor leading to limb muscle dysfunction is deconditioning, whereas respiratory muscle dysfunction is mostly the result of pulmonary hyperinflation. However, both limb and respiratory muscles are also influenced by other negative factors, including smoking, systemic inflammation, nutritional abnormalities, exacerbations and some drugs. Limb muscle weakness is generally diagnosed through voluntary isometric maneuvers such as handgrip or quadriceps muscle contraction (dynamometry); while respiratory muscle loss of strength is usually recognized through a decrease in maximal static pressures measured at the mouth. Both types of measurements have validated reference values. Respiratory muscle strength can also be evaluated determining esophageal, gastric and transdiaphragmatic maximal pressures although there is a lack of widely accepted reference equations. Non-volitional maneuvers, obtained through electrical or magnetic stimulation, can be employed in patients unable to cooperate. Muscle endurance can also be assessed, generally using repeated submaximal maneuvers until exhaustion, but no validated reference values are available yet. The treatment of muscle dysfunction is multidimensional and includes improvement in lifestyle habits (smoking abstinence, healthy diet and a good level of physical activity, preferably outside), nutritional measures (diet supplements and occasionally, anabolic drugs), and different modalities of general and muscle training.

Noninvasive Ventilation

Noninvasive ventilation (NIV) has assumed a prominent role in the treatment of patients with both hypoxemic and hypercapnic acute respiratory failure (ARF). The main theoretic advantages of NIV include avoiding side effects and complications associated with endotracheal intubation, improving patient comfort, and preserving airway defense mechanisms. Factors that affect the success of NIV in patients with ARF are clinicians' expertise, selection of patient, choice of interface, selection of ventilator setting, proper monitoring, and patient motivation. Advances in the understanding of the physiologic aspects of using NIV through different interfaces and ventilator modalities have improved patient-machine interaction, thus enhancing favorable NIV outcome.

Intensive care and invasive ventilation in the elderly patient, implications of chronic lung disease and comorbidities

Aims: Elderly patients have an increasing prevalence of illness that requires consideration of critical care and invasive ventilatory support. Although critical care of even the very elderly can provide value, with increasing age the potential risks of treatment and diminishing returns with respect to quality and quantity of life result in a need for careful evaluation. Variable combinations of impaired organ function, active disease and residual pathology from past disease and injury all affect critical care, with the consequence that the elderly are a very heterogeneous population. Recognizing that critical care is a limited resource, it is important to identify patients who may be at increased risk or least likely to benefit from treatment. Patients with functional impairments, nutritional deficiencies and multiple comorbidities may be at highest risk of poor outcomes. Those with very severe disease, extreme age and requirements for prolonged ventilatory support have high in-hospital mortality. Functional impairments, comorbidities and severity of illness are usually more important considerations than chronologic age. The objective of this review is to identify how common problems of the elderly affect critical care and decisions concerning use of invasive ventilatory support.

Noninvasive ventilation for severely acidotic patients in respiratory intermediate care units : Precision medicine in intermediate care units

Background

Severe acidosis can cause noninvasive ventilation (NIV) failure in chronic obstructive pulmonary disease (COPD) patients with acute hypercapnic respiratory failure (AHRF). NIV is therefore contraindicated outside of intensive care units (ICUs) in these patients. Less is known about NIV failure in patients with acute cardiogenic pulmonary edema (ACPE) and obesity hypoventilation syndrome (OHS). Therefore, the objective of the present study was to compare NIV failure rates between patients with severe and non-severe acidosis admitted to a respiratory intermediate care unit (RICU) with AHRF resulting from ACPE, COPD or OHS.

Methods

We prospectively included acidotic patients admitted to seven RICUs, where they were provided NIV as an initial ventilatory support measure. The clinical characteristics, pH evolutions, hospitalization or RICU stay durations and NIV failure rates were compared between patients with a pH ≥ 7.25 and a pH < 7.25. Logistic regression analysis was performed to determine the independent risk factors contributing to NIV failure.

Results

We included 969 patients (240 with ACPE, 540 with COPD and 189 with OHS). The baseline rates of severe acidosis were similar among the groups (45 % in the ACPE group, 41 % in the COPD group, and 38 % in the OHS group). Most of the patients with severe acidosis had increased disease severity compared with those with non-severe acidosis: the APACHE II scores were 21 ± 7.2 and 19 ± 5.8 for the ACPE patients (p < 0.05), 20 ± 5.7 and 19 ± 5.1 for the COPD patients (p < 0.01) and 18 ± 5.9 and 17 ± 4.7 for the OHS patients, respectively (NS). The patients with severe acidosis also exhibited worse arterial blood gas parameters: the PaCO₂ levels were 87 ± 22 and 70 ± 15 in the ACPE patients (p < 0.001), 87 ± 21 and 76 ± 14 in the COPD patients, and 83 ± 17 and 74 ± 14 in the OHS patients (NS)., respectively Further, the patients with severe acidosis required a longer duration to achieve pH normalization than those with non-severe acidosis (patients with a normalized pH after the first hour: ACPE, 8 % vs. 43 %, p < 0.001; COPD, 11 % vs. 43 %, p < 0.001; and OHS, 13 % vs. 51 %, p < 0.001), and they had longer RICU stays, particularly those in the COPD group (ACPE, 4 ± 3.1 vs. 3.6 ± 2.5, NS; COPD, 5.1 ± 3 vs. 3.6 ± 2.1, p < 0.001; and OHS, 4.3 ± 2.6 vs. 3.7 ± 3.2, NS). The NIV failure rates were similar between the patients with severe and non-severe acidosis in the three disease groups (ACPE, 16 % vs. 12 %; COPD, 7 % vs. 7 %; and OHS, 11 % vs. 4 %). No common predictive factor for NIV failure was identified among the groups.

Conclusions

ACPE, COPD and OHS patients with AHRF and severe acidosis (pH ≤ 7.25) who are admitted to an RICU can be successfully treated with NIV in these units. These results may be used to determine precise RICU admission criteria.

Electronic supplementary material

The online version of this article (doi:10.1186/s12890-016-0262-9) contains supplementary material, which is available to authorized users.

Predicting success of high-flow nasal cannula in pneumonia patients with hypoxemic respiratory failure: The utility of the ROX index

PURPOSE

The purpose of the study is to describe early predictors and to develop a prediction tool that accurately identifies the need for mechanical ventilation (MV) in pneumonia patients with hypoxemic acute respiratory failure (ARF) treated with high-flow nasal cannula (HFNC).

MATERIALS AND METHODS

This is a 4-year prospective observational 2-center cohort study including patients with severe pneumonia treated with HFNC. High-flow nasal cannula failure was defined as need for MV. ROX index was defined as the ratio of pulse oximetry/fraction of inspired oxygen to respiratory rate.

RESULTS

One hundred fifty-seven patients were included, of whom 44 (28.0%) eventually required MV (HFNC failure). After 12 hours of HFNC treatment, the ROX index demonstrated the best prediction accuracy (area under the receiver operating characteristic curve 0.74 [95% confidence interval, 0.64-0.84]; P<.002). The best cutoff point for the ROX index was estimated to be 4.88. In the Cox proportional hazards model, a ROX index greater than or equal to 4.88 measured after 12 hours of HFNC was significantly associated with a lower risk for MV (hazard ratio, 0.273 [95% confidence interval, 0.121-0.618]; P=.002), even after adjusting for potential confounding.

CONCLUSIONS

In patients with ARF and pneumonia, the ROX index can identify patients at low risk for HFNC failure in whom therapy can be continued after 12 hours.

Can patients with moderate to severe acute respiratory failure from COPD be treated safely with noninvasive mechanical ventilation on the ward?

Purpose

Noninvasive mechanical ventilation (NIMV) usage outside of intensive care unit is not recommended in patients with COPD for severe acute respiratory failure (ARF). We assessed the factors associated with failure of NIMV in patients with ARF and severe acidosis admitted to the emergency department and followed on respiratory ward.

Patients and methods

This is a retrospective observational cohort study conducted in a tertiary teaching hospital specialized in chest diseases and thoracic surgery between June 1, 2013 and May 31, 2014. COPD patients who were admitted to our emergency department due to ARF were included. Patients were grouped according to the severity of acidosis into two groups: group 1 (pH=7.20–7.25) and group 2 (pH=7.26–7.30).

Results

Group 1 included 59 patients (mean age: 70±10 years, 30.5% female) and group 2 included 171 patients (mean age: 67±11 years, 28.7% female). On multivariable analysis, partial arterial oxygen pressure to the inspired fractionated oxygen (PaO₂/FiO₂) ratio <200, delta pH value <0.30, and pH value <7.31 on control arterial blood gas after NIMV in the emergency room and peak C-reactive protein were found to be the risk factors for NIMV failure in COPD patients with ARF in the ward.

Conclusion

NIMV is effective not only in mild respiratory failure but also with severe forms of COPD patients presenting with severe exacerbation. The determination of the failure criteria of NIMV and the expertise of the team is critical for treatment success.

Noninvasive and invasive positive pressure ventilation for acute respiratory failure in critically ill patients: a comparative cohort study

BACKGROUND

Noninvasive positive pressure ventilation (NPPV) for acute respiratory failure in the intensive care unit (ICU) is associated with a marked reduction in intubation rate, complications, hospital length of stay and mortality. Multiple studies have indicated that patients failing NPPV have worse outcomes compared with patients with successful NPPV treatment; however limited data is available on risks associated with NPPV failure resulting in (delayed) intubation and outcomes compared with initial intubation. The purpose of this study is to assess rates and predictors of NPPV failure and to compare hospital outcomes of patients with NPPV failure with those patients primarily intubated without a prior NPPV trial.

METHODS

A retrospective observational study using data from patients with acute respiratory failure admitted to the ICU in the period 2013-2014. All patients treated with NPPV were evaluated. A sample of patients who were primarily intubated was randomly selected to serve as controls for the group of patients who failed NPPV.

RESULTS

NPPV failure was recorded in 30.8% of noninvasively ventilated patients and was associated with longer ICU stay [OR, 1.16, 95% confidence interval (95% CI): 1.04-1.30] and lower survival rates (OR, 0.10, 95% CI: 0.02-0.59) compared with NPPV success. Multivariate analysis showed presence of severe sepsis at study entry, higher Simplified Acute Physiology II Score (SAPS-II) score, lower ratio of arterial oxygen tension to fraction of inspired oxygen (PF-ratio) and lower plasma glucose were predictors for NPPV failure. After controlling for potential confounders, patients with NPPV failure did not show any difference in hospital outcomes compared with patients who were primarily intubated.

CONCLUSIONS

Patients with acute respiratory failure and NPPV failure have worse outcomes compared with NPPV success patients, however not worse than initially intubated patients. An initial trial of NPPV therefore may be suitable in selected cases of patients with acute respiratory failure, since NPPV could be potentially beneficial and does not seem to result in worse outcome in case of NPPV failure compared to primary intubation. A prospective trial is warranted to confirm findings.

Acidemia in severe acute cardiogenic pulmonary edema treated with noninvasive pressure support ventilation: a single-center experience

In clinical practice, acidotic patients with acute cardiogenic pulmonary edema (ACPE) are commonly considered more severe in comparison with nonacidotic patients, and data on the outcome of these patients treated with noninvasive pressure support ventilation (NIV) are lacking.The present investigation was aimed at assessing whether acidosis on admission (pH < 7.35) was associated with adverse outcome in 65 consecutive patients with ACPE treated with NIV and admitted to our Intensive Cardiac Care Unit (ICCU).In our population, 28 patients were acidotic (28 of 65, 43.1%), whereas 41 patients were not (37 of 65, 56.9%). According to the Repeated Measures General Linear Model, pCO2 values significantly changed throughout the 2-h NIV treatment (P = 0.019) in both groups (P = 0001). In acidotic patients, pCO2 significantly decreased (51.9 ± 15.3 → 47.0 ± 12.8 → 44.8 ± 12.7), whereas they increased in the nonacidotic subgroup (36.8 ± 6.5 → 36.9 ± 7.2 → 37.6 ± 6.4). No difference was observed in intubation rate between acidotic (eight patients, 28.6%) and nonacidotic patients (12 patients, 32.4%) (P = 0.738). In-ICCU mortality rate did not differ between (13 patients, 35.1%) and nonacidotic patients (nine patients, 32.1%) (P = 0.801).Our data strongly suggest that in patients with severe ACPE treated with NIV, the presence of acidosis is not associated with adverse outcomes (early mortality and intubation rates) in these patients.

Work of breathing using different interfaces in spontaneous positive pressure ventilation: helmet, face-mask, and endotracheal tube

PURPOSE

Noninvasive positive pressure ventilation (NPPV) using a helmet is expected to cause inspiratory trigger delay due to the large collapsible and compliant chamber. We compared the work of breathing (WOB) of NPPV using a helmet or a full face-mask with that of invasive ventilation by tracheal intubation.

METHODS

We used a lung model capable of simulating spontaneous breathing (LUNGOO; Air Water Inc., Japan). LUNGOO was set at compliance (C) = 50 mL/cmH2O and resistance (R) = 5 cmH2O/L/s for normal lung simulation, C = 20 mL/cmH2O and R = 5 cmH2O/L/s for restrictive lung, and C = 50 mL/cmH2O and R = 20 cmH2O/L/s for obstructive lung. Muscle pressure was fixed at 25 cmH2O and respiratory rate at 20 bpm. Pressure support ventilation and continuous positive airway pressure were performed with each interface placed on a dummy head made of reinforced plastic that was connected to LUNGOO. We tested the inspiratory WOB difference between the interfaces with various combinations of ventilator settings (positive end-expiratory pressure 5 cmH2O; pressure support 0, 5, and 10 cmH2O).

RESULTS

In the normal lung and restrictive lung models, WOB decreased more with the face-mask than the helmet, especially when accompanied by the level of pressure support. In the obstructive lung model, WOB with the helmet decreased compared with the other two interfaces. In the mixed lung model, there were no significant differences in WOB between the three interfaces.

CONCLUSION

NPPV using a helmet is more effective than the other interfaces for WOB in obstructive lung disease.

Sepsis and Acute Respiratory Distress Syndrome: Recent Update

Severe sepsis or septic shock is characterized by an excessive inflammatory response to infectious pathogens. Acute respiratory distress syndrome (ARDS) is a devastating complication of severe sepsis, from which patients have high mortality. Advances in treatment modalities including lung protective ventilation, prone positioning, use of neuromuscular blockade, and extracorporeal membrane oxygenation, have improved the outcome over recent decades, nevertheless, the mortality rate still remains high. Timely treatment of underlying sepsis and early identification of patients at risk of ARDS can help to decrease its development. In addition, further studies are needed regarding pathogenesis and novel therapies in order to show promising future treatments of sepsis-induced ARDS.

Efficacy of non-invasive mechanical ventilation in the general ward in patients with chronic obstructive pulmonary disease admitted for hypercapnic acute respiratory failure and pH < 7.35: a feasibility pilot study

AIM

To date non-invasive (NIV) mechanical ventilation use is not recommended in chronic obstructive pulmonary disease (COPD) patients with acute respiratory failure (ARF) and pH < 7.30 outside a 'protected environment'. We assessed NIV efficacy and feasibility in improving arterial blood gases (ABG) and in-hospital outcome in patients with ARF and severe respiratory acidosis (RA) admitted to an experienced rural medical ward.

METHODS

This paper is a prospective pilot cohort study conducted in the General Medicine Ward of Budrio's District Hospital. Two hundred and seventy-two patients with ARF were admitted to our Department, 112, meeting predefined inclusion criteria (pH < 7.35, PaCO2 > 45 mmHg). Patients were divided according to the severity of acidosis into: group A (pH < 7.26), group B (7.26 ≤ pH < 7.30) and group C (7.30 ≤ pH < 7.35). ABG were assessed at admission, at 2-6 h, 24 h, 48 h and at discharge.

RESULTS

Group A included 55 patients (24 men, mean age: 80.8 ± 8.3 years), group B 31 (12 men, mean age: 80.3 ± 9.4 years) and group C 26 (15 men, mean age: 78.6 ± 9.9 years). ABG improved within the first hours in 92/112 (82%) patients, who were all successfully discharged. Eighteen percent (20/112) of the patients died during the hospital stay, no significant difference emerged in mortality rate (MR) within the groups (23%, 16% and 8%, for groups A, B and C, respectively) and between patients with or without pneumonia: 8/29 (27%) versus 12/83 (14%). On multivariable analysis, only age and Glasgow Coma Scale had an impact on the clinical outcome.

CONCLUSION

In a non-'highly protected' environment such as an experienced medical ward of a rural hospital, NIV is effective not only in patients with mild, but also with severe forms of RA. MR did not vary according to the level of initial pH.

[Hypercapnic respiratory failure. Pathophysiology, indications for mechanical ventilation and management]

BACKGROUND

Acute hypercapnic respiratory failure is mostly seen in patients with chronic obstructive pulmonary disease (COPD) and obesity hypoventilation syndrome (OHS). Depending on the underlying cause it may be associated with hypoxemic respiratory failure and places high demands on mechanical ventilation.

OBJECTIVE

Presentation of the current knowledge on indications and management of mechanical ventilation in patients with hypercapnic respiratory failure.

MATERIAL AND METHODS

Review of the literature.

RESULTS

Important by the selection of mechanical ventilation procedures is recognition of the predominant pathophysiological component. In hypercapnic respiratory failure with a pH < 7.35 non-invasive ventilation (NIV) is primarily indicated unless there are contraindications. In patients with severe respiratory acidosis NIV requires a skilled and experienced team and close monitoring in order to perceive a failure of NIV. In acute exacerbation of COPD ventilator settings need a long expiration and short inspiration time to avoid further hyperinflation and an increase in intrinsic positive end-expiratory pressure (PEEP). Ventilation must be adapted to the pathophysiological situation in patients with OHS or overlap syndrome. If severe respiratory acidosis and hypercapnia cannot be managed by mechanical ventilation therapy alone extracorporeal venous CO2 removal may be necessary. Reports on this approach in awake patients are available.

CONCLUSION

The use of NIV is the predominant treatment in patients with hypercapnic respiratory failure but close monitoring is necessary in order not to miss the indications for intubation and invasive ventilation. Methods of extracorporeal CO2 removal especially in awake patients need further evaluation.

Predicting Healthcare Utilization by Patients Admitted for COPD Exacerbation

BACKGROUND

Healthcare utilization, especially length of hospital stay and ICU admission, for acute exacerbation of chronic obstructive pulmonary disease (AECOPD) determine overall outcomes in terms of morbidity, mortality and cost burden. Predicting prolonged hospital stay (PHS) and prolonged intensive care (PIC) for AECOPD is useful for rational allocation of resources in healthcare centres.

AIM

To characterize the pattern of healthcare utilization by COPD patients hospitalized for acute exacerbation, and to identify clinical and laboratory predictors of 'prolonged hospital stay' (PHS) and 'prolonged intensive care'(PIC).

MATERIALS AND METHODS

This study attempted through retrospective data analysis, to identify risk factors and evolve prediction models for increased healthcare utilization namely PHS and PIC for AECOPD. The data were extracted from 255 eligible admissions for AECOPD by 166 patients from Aug 2012 to July 2013. Logistic regression analysis was used for identifying predictors and models were tested with area under receiver operating characteristic curve.

RESULTS

Independent predictors of prolonged hospital stay (≥ 6 days) were chronic respiratory failure at baseline, low saturation at admission, high HbA1c level and positive isolates in sputum culture. Independent predictors of prolonged intensive care (for ≥ 48 hours) were past history of pulmonary tuberculosis, chronic respiratory failure at baseline, low saturation at admission, high leukocyte count and positive culture isolates in sputum. Prediction models evolved from variables available at admission showed AUC 0.805 (95% CI 0.729 - 0.881) and 0.825 (95% CI 0.75 - 0.90) for PHS and ICU admissions respectively.

CONCLUSION

Our prediction models derived from simple and easily available variables show good discriminative properties in predicting PHS and PIC for AECOPD. When prospectively validated, these models are useful for rational allocation of services especially in resource limited settings.

An unsupervised learning method to identify reference intervals from a clinical database

Reference intervals are critical for the interpretation of laboratory results. The development of reference intervals using traditional methods is time consuming and costly. An alternative approach, known as an a posteriori method, requires an expert to enumerate diagnoses and procedures that can affect the measurement of interest. We develop a method, LIMIT, to use laboratory test results from a clinical database to identify ICD9 codes that are associated with extreme laboratory results, thus automating the a posteriori method. LIMIT was developed using sodium serum levels, and validated using potassium serum levels, both tests for which harmonized reference intervals already exist. To test LIMIT, reference intervals for total hemoglobin in whole blood were learned, and were compared with the hemoglobin reference intervals found using an existing a posteriori approach. In addition, prescription of iron supplements were used to identify individuals whose hemoglobin levels were low enough for a clinician to choose to take action. This prescription data indicating clinical action was then used to estimate the validity of the hemoglobin reference interval sets. Results show that LIMIT produces usable reference intervals for sodium, potassium and hemoglobin laboratory tests. The hemoglobin intervals produced using the data driven approaches consistently had higher positive predictive value and specificity in predicting an iron supplement prescription than the existing intervals. LIMIT represents a fast and inexpensive solution for calculating reference intervals, and shows that it is possible to use laboratory results and coded diagnoses to learn laboratory test reference intervals from clinical data warehouses.

Predictive Factors for the Effect of Treatment by Noninvasive Ventilation in Patients with Respiratory Failure as a Result of Acute Exacerbation of the Chronic Obstructive Pulmonary Disease

BACKGROUND:

Noninvasive mechanical ventilation (NIV) applies ventilator support through the patient’s upper airway using a mask.

AIM:

The aim of the study is to define factors that will point out an increased risk of NIV failure in patients with exacerbation of Chronic Obstructive Pulmonary Disease (COPD).

PATIENTS AND METHODS:

Patients over the age of 40, treated with NIV, were prospectively recruited. After data processing, the patients were divided into two groups: 1) successful NIV treatment group; 2) failed NIV treatment group.

RESULTS:

On admission arterial pH and Glasgow coma scale (GCS) levels were lower (pH: p < 0.05, GCS: p < 0.05), and Acute Physiology and Chronic Health Evaluation II (APACHE) score and PaCO₂ were higher (p < 0.05) in the NIV failure group. Arterial pH was lower (p < 0.05) and PaCO₂ and respiratory rate were higher (p < 0.05) after 1h, and arterial pH was lower (p < 0.05) and PaCO₂ (p < 0.05), respiratory and heart rate were higher (p < 0.05) after 4h in the NIV failure group.

CONCLUSION:

Measurement and monitoring of certain parameters may be of value in terms of predicting the effectiveness of NIV treatment.

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.

Lights and shadows of non-invasive mechanical ventilation for chronic obstructive pulmonary disease (COPD) exacerbations

Despite the overwhelming evidence justifying the use of non-invasive ventilation (NIV) for providing ventilatory support in chronic obstructive pulmonary disease (COPD) exacerbations, recent studies demonstrated that its application in real-life settings remains suboptimal. European clinical audits have shown that 1) NIV is not invariably available, 2) its availability depends on countries and hospital sizes, and 3) numerous centers declare their inability to provide NIV to all of the eligible patients presenting throughout the year. Even with an established indication, the use of NIV in acute respiratory failure due to COPD exacerbations faces important challenges. First, the location and personnel using NIV should be carefully selected. Second, the use of NIV is not straightforward despite the availability of technologically advanced ventilators. Third, NIV therapy of critically ill patients requires a thorough knowledge of both respiratory physiology and existing ventilatory devices. Accordingly, an optimal team-training experience, the careful selection of patients, and special attention to the selection of devices are critical for optimizing NIV outcomes. Additionally, when applied, NIV should be closely monitored, and endotracheal intubation should be promptly available in the case of failure. Another topic that merits careful consideration is the use of NIV in the elderly. This patient population is particularly fragile, with several physiological and social characteristics requiring specific attention in relation to NIV. Several other novel indications should also be critically examined, including the use of NIV during fiberoptic bronchoscopy or transesophageal echocardiography, as well as in interventional cardiology and pulmonology. The present narrative review aims to provide updated information on the use of NIV in acute settings to improve the clinical outcomes of patients hospitalized for COPD exacerbations.

Chronic obstructive pulmonary disease and diabetes mellitus: a systematic review of the literature

The objective of this systematic review was to discuss our current understanding of the complex relationship between chronic obstructive pulmonary disease (COPD) and type-2 diabetes mellitus (T2DM). We performed a systematic search of the literature related to both COPD and diabetes using PubMed. Relevant data connecting both diseases were compiled and discussed. Recent evidence suggests that diabetes can worsen the progression and prognosis of COPD; this may result from the direct effects of hyperglycemia on lung physiology, inflammation or susceptibility to bacterial infection. Conversely, it has also been suggested that COPD increases the risk of developing T2DM as a consequence of inflammatory processes and/or therapeutic side effects related to the use of high-dose corticosteroids. In conclusion, although there is evidence to support a connection between COPD and diabetes, additional research is needed to better understand these relationships and their possible implications.

The use of non-invasive ventilation in very old patients with hypercapnic acute respiratory failure because of COPD exacerbation

AIMS

We prospectively enrolled 207 patients (121 were 75 or older and 86 younger than 75) who were admitted to three Respiratory Monitoring Units. The primary outcomes were intubation and mortality rates; the secondary outcomes were changes in arterial blood gases analysis, non-invasive ventilation (NIV) duration and length of hospital stay.

RESULTS

Hospital mortality was similar in the two groups, as were intubation rates. The proportion who died in the very old patient group was 19.8% (24/121) vs. 10.4% (9/86) in the younger group. Intubation rate was 10.7% (13/121) in the very old patient group and 11.6% (10/86) in the younger group. The presence of comorbidities, the severity of illness (SAPS II), the level of consciousness, NIV failure (intubation), absolute value of pH prior to NIV, as well as the changes in pH and paCO2 and PaO2 /FiO2 after 2 h of NIV, were the variables associated with higher mortality. Very old patients had significantly higher NIV duration than younger patients (69.0 ± 47.0 vs. 57.0 ± 27.0 h) (p ≤ 0.03) and hospital stays (11.6 ± 3.8 vs. 8.4 ± 1.4) (p ≤ 0.02).

CONCLUSIONS

The use of NIV in very old patients was effective in many cases. Endotracheal intubation after NIV failure was not efficacious in either group.

Prolonged weaning: from the intensive care unit to home

Weaning is the process of withdrawing mechanical ventilation which starts with the first spontaneous breathing trial (SBT). Based on the degree of difficulty and duration, weaning is classified as simple, difficult and prolonged. Prolonged weaning, which includes patients who fail 3 SBTs or are still on mechanical ventilation 7 days after the first SBT, affects a relatively small fraction of mechanically ventilated ICU patients but these, however, requires disproportionate resources. There are several potential causes which can lead to prolonged weaning. It is nonetheless important to understand the problem from the point of view of each individual patient in order to adopt appropriate treatment and define precise prognosis. An otherwise stable patient who remains on mechanical ventilation will be considered for transfer to a specialized weaning unit (SWU). Though there is not a precise definition, SWU can be considered as highly specialized and protected environments for patients requiring mechanical ventilation despite resolution of the acute disorder. Proper staffing, well defined short-term and long-term goals, attention to psychological and social problems represent key determinants of SWU success. Some patients cannot be weaned, either partly or entirely, and may require long-term home mechanical ventilation. In these cases the logistics relating to caregivers and the equipment must be carefully considered and addressed.

Current opinions on non-invasive ventilation as a treatment for chronic obstructive pulmonary disease

PURPOSE OF REVIEW

This review examines the current reports, the evidence and the issues surrounding the use of non-invasive ventilation (NIV) for the treatment of chronic obstructive pulmonary disease (COPD) in both the acute and domiciliary setting.

RECENT FINDINGS

With the increasing use of NIV, more recent studies have focused on investigating the outcomes of our current practice. Although overall morbidity and mortality outcomes in the acute setting have improved, patients who initially stabilize but then deteriorate during an acute exacerbation of COPD have a poor prognosis. The focus must be on phenotyping this high-risk group to investigate other potential rescue treatments, including extracorporeal carbon dioxide removal. Indeed, phenotyping appears to favour the obese COPD patient, which may have a protective role in reducing the risk of NIV failure and recurrent hospital admissions. Randomized controlled trial evidence to support the use of NIV in a domiciliary setting as a treatment for COPD is awaited, and until the data from a number of ongoing clinical trials are available, the wide variation in global practice will continue. Increased understanding of patient ventilator asynchrony has improved domiciliary NIV set up, which is expected to enhance the tolerability of NIV, promoting patient adherence.

SUMMARY

NIV is the established standard of care to treat acute hypercapnic exacerbations of COPD postoptimal medical management. NIV as a long-term treatment for COPD remains controversial based on the evidence from the published randomized controlled trials. With increasing experience of NIV therapy, patient outcomes are improving; however, further work is still required to better characterize and target the patients who will most benefit from NIV.

Determinants of noninvasive ventilation success or failure in morbidly obese patients in acute respiratory failure

PURPOSE

Acute respiratory failure (ARF) is a common life-threatening complication in morbidly obese patients with obesity hypoventilation syndrome (OHS). We aimed to identify the determinants of noninvasive ventilation (NIV) success or failure for this indication.

METHODS

We prospectively included 76 consecutive patients with BMI>40 kg/m2 diagnosed with OHS and treated by NIV for ARF in a 15-bed ICU of a tertiary hospital.

RESULTS

NIV failed to reverse ARF in only 13 patients. Factors associated with NIV failure included pneumonia (n = 12/13, 92% vs n = 9/63, 14%; p<0.0001), high SOFA (10 vs 5; p<0.0001) and SAPS2 score (63 vs 39; p<0.0001) at admission. These patients often experienced poor outcome despite early resort to endotracheal intubation (in-hospital mortality, 92.3% vs 17.5%; p<0.001). The only factor significantly associated with successful response to NIV was idiopathic decompensation of OHS (n = 30, 48% vs n = 0, 0%; p = 0.001). In the NIV success group (n = 63), 33 patients (53%) experienced a delayed response to NIV (with persistent hypercapnic acidosis during the first 6 hours).

CONCLUSIONS

Multiple organ failure and pneumonia were the main factors associated with NIV failure and death in morbidly obese patients in hypoxemic ARF. On the opposite, NIV was constantly successful and could be safely pushed further in case of severe hypercapnic acute respiratory decompensation of OHS.

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.

Noninvasive ventilation and the upper airway: should we pay more attention?

In an effort to reduce the complications related to invasive ventilation, the use of noninvasive ventilation (NIV) has increased over the last years in patients with acute respiratory failure. However, failure rates for NIV remain high in specific patient categories. Several studies have identified factors that contribute to NIV failure, including low experience of the medical team and patient–ventilator asynchrony. An important difference between invasive ventilation and NIV is the role of the upper airway. During invasive ventilation the endotracheal tube bypasses the upper airway, but during NIV upper airway patency may play a role in the successful application of NIV. In response to positive pressure, upper airway patency may decrease and therefore impair minute ventilation. This paper aims to discuss the effect of positive pressure ventilation on upper airway patency and its possible clinical implications, and to stimulate research in this field.

[Ventilation strategies for chronic obstructive pulmonary disease]

Chronic obstructive pulmonary disease (COPD) is considered to be one of the most frequent pulmonary diseases in industrialized countries. Non-invasive ventilation (NIV) is the first choice therapy in acute exacerbations of chronic hypercapnic respiratory failure (AE-COPD). Effective delivery of NIV requires a specialized interdisciplinary team with sufficient monitoring. NIV is delivered as assisted positive pressure ventilation where high inspiratory flow and peak pressure are required. The external positive end expiratory pressure (PEEP) should be adjusted to the intrinsic PEEP. Criteria of success are improvement in the clinical, especially neurological condition as well as improvement of pH and PaCO(2). Patients with a pH between 7.25 and 7.35 have demonstrated most benefit from NIV. In cases of patients not responding to NIV endotracheal intubation should be initiated in a timely manner. Assisted ventilation modes are preferred over controlled ventilation modes in intubated COPD patients. Settings of respirators have to be aimed at a reduction of intrinsic PEEP and dynamic hyperinflation. This includes sufficient external PEEP, long expiration times and low respiratory frequencies even allowing for permissive hypercapnia.

Noninvasive ventilation: practical advice

PURPOSE OF REVIEW

This critical review discusses the key points that would be of practical help for the clinician who applies noninvasive ventilation (NIV) for treatment of patients with acute respiratory failure (ARF).

RECENT FINDINGS

In recent years, the growing role of NIV in the acute care setting has led to the development of technical innovations to overcome the problems related to gas leakage and dead space. A considerable amount of research has been conducted to improve the quality of the devices as well as optimize ventilation modes used to administer NIV. As a result, also mechanical ventilators have been implemented with modalities aimed at delivering NIV.

SUMMARY

The success of NIV in patients with ARF depends on several factors, including the skills of the clinician, selection of patient, choice of interface, selection of ventilation mode and ventilator setting, monitoring, and the motivation of the patient. Recent advances in the understanding of the physiological aspects of using NIV through different interfaces and ventilator settings have led to improve patient-machine interaction, enhancing favorable NIV outcome.

Rescue therapy by switching to total face mask after failure of face mask-delivered noninvasive ventilation in do-not-intubate patients in acute respiratory failure

OBJECTIVE

To evaluate the impact of switching to total face mask in cases where face mask-delivered noninvasive mechanical ventilation has already failed in do-not-intubate patients in acute respiratory failure.

DESIGN AND SETTING

Prospective observational study in an ICU and a respiratory stepdown unit over a 12-month study period.

INTERVENTION

Switching to total face mask, which covers the entire face, when noninvasive mechanical ventilation using facial mask (oronasal mask) failed to reverse acute respiratory failure.

PATIENTS

Seventy-four patients with a do-not-intubate order and treated by noninvasive mechanical ventilation for acute respiratory failure.

MAIN RESULTS

Failure of face mask-delivered noninvasive mechanical ventilation was associated with a three-fold increase in in-hospital mortality (36% vs. 10.5%; p = 0.009). Nevertheless, 23 out of 36 patients (64%) in whom face mask-delivered noninvasive mechanical ventilation failed to reverse acute respiratory failure and, therefore, switched to total face mask survived hospital discharge. Reasons for switching from facial mask to total face mask included refractory hypercapnic acute respiratory failure (n = 24, 66.7%), painful skin breakdown or facial mask intolerance (n = 11, 30%), and refractory hypoxemia (n = 1, 2.7%). In the 24 patients switched from facial mask to total face mask because of refractory hypercapnia, encephalopathy score (3 [3-4] vs. 2 [2-3]; p < 0.0001), PaCO2 (87 ± 25 mm Hg vs. 70 ± 17 mm Hg; p < 0.0001), and pH (7.24 ± 0.1 vs. 7.32 ± 0.09; p < 0.0001) significantly improved after 2 hrs of total face mask-delivered noninvasive ventilation. Patients switched early to total face mask (in the first 12 hrs) developed less pressure sores (n = 5, 24% vs. n = 13, 87%; p = 0.0002), despite greater length of noninvasive mechanical ventilation within the first 48 hrs (44 hrs vs. 34 hrs; p = 0.05) and less protective dressings (n = 2, 9.5% vs. n = 8, 53.3%; p = 0.007). The optimal cutoff value for face mask-delivered noninvasive mechanical ventilation duration in predicting facial pressure sores was 11 hrs (area under the receiver operating characteristic curve, 0.86 ± 0.04; 95% confidence interval 0.76-0.93; p < 0.0001; sensitivity, 84%; specificity, 71%).

CONCLUSION

In patients in hypercapnic acute respiratory failure, for whom escalation to intubation is deemed inappropriate, switching to total face mask can be proposed as a last resort therapy when face mask-delivered noninvasive mechanical ventilation has already failed to reverse acute respiratory failure. This strategy is particularly adapted to provide prolonged periods of continuous noninvasive mechanical ventilation while preventing facial pressure sores.

Comparative effectiveness of noninvasive ventilation vs invasive mechanical ventilation in chronic obstructive pulmonary disease patients with acute respiratory failure

BACKGROUND

Limited evidence exists on the comparative effectiveness of noninvasive ventilation (NIV) vs invasive mechanical ventilation (IMV) in acute exacerbation of chronic obstructive pulmonary disease (AECOPD) patients with respiratory failure.

OBJECTIVES

To characterize the use of NIV and IMV, and to compare the effectiveness of NIV vs IMV in AECOPD.

DESIGN AND PATIENTS

Retrospective cohort study using data from the 2006-2008 Nationwide Emergency Department Sample. Emergency department visits for AECOPD with acute respiratory failure were identified with codes from the International Classification of Diseases, Ninth Revision, Clinical Modification.

MEASURES

The outcome measures were inpatient mortality, hospital length of stay, hospital charges, and complications.

RESULTS

There were an estimated 101,000 visits annually for AECOPD with acute respiratory failure; 96% were admitted to the hospital. Of these, NIV use increased from 14% in 2006 to 16% in 2008 (P=0.049). Use of NIV, however, varied widely between hospitals, ranging from 0% to 100% with a median of 11%. Noninvasive ventilation was more often used in higher-case volume, Northeastern hospitals. In a propensity score analysis, NIV use, compared with IMV, was associated with lower inpatient mortality (risk ratio: 0.54, 95% confidence interval [CI]: 0.50-0.59), shortened hospital length of stay (-3.2 days; 95% CI: -3.4 to -2.9 days), lower hospital charges (-$35,012; 95% CI: -$36,848 to -$33,176), and lower risk of iatrogenic pneumothorax (0.05% vs 0.5%, P<0.001).

CONCLUSIONS

Although NIV use is increasing in US hospitals, its adoption remains low and varies widely between hospitals. Our observational study suggests NIV appears to be more effective and safer than IMV for AECOPD in the real-world setting.

Anemia and performance status as prognostic markers in acute hypercapnic respiratory failure due to chronic obstructive pulmonary disease

BACKGROUND

In patients with acute hypercapnic respiratory failure (AHRF) during exacerbations of COPD, mortality can be high despite noninvasive ventilation (NIV). For some, AHRF is terminal and NIV is inappropriate. However there is no definitive method of identifying patients who are unlikely to survive. The aim of this study was to identify factors associated with inpatient mortality from AHRF with respiratory acidosis due to COPD.

METHODS

COPD patients presenting with AHRF and who were treated with NIV were studied prospectively. The forced expiratory volume in 1 second (FEV1), World Health Organization performance status (WHO-PS), clinical observations, a composite physiological score (Early Warning Score), routine hematology and biochemistry, and arterial blood gases prior to commencing NIV, were recorded.

RESULTS

In total, 65 patients were included for study, 29 males and 36 females, with a mean age of 71 ± 10.5 years. Inpatient mortality in the group was 33.8%. Mortality at 30 days and 12 months after admission were 38.5% and 58.5%, respectively. On univariate analysis, the variables associated with inpatient death were: WHO-PS ≥ 3, long-term oxygen therapy, anemia, diastolic blood pressure < 70 mmHg, Early Warning Score ≥ 3, severe acidosis (pH < 7.20), and serum albumin < 35 g/L. On multivariate analysis, only anemia and WHO-PS ≥ 3 were significant. The presence of both predicted 68% of inpatient deaths, with a specificity of 98%.

CONCLUSION

WHO-PS ≥ 3 and anemia are prognostic factors in AHRF with respiratory acidosis due to COPD. A combination of the two provides a simple method of identifying patients unlikely to benefit from NIV.

Early non-invasive ventilation treatment for severe influenza pneumonia

The role of non-invasive ventilation (NIV) in acute respiratory failure caused by viral pneumonia remains controversial. Our objective was to evaluate the use of NIV in a cohort of (H1N1)v pneumonia. Usefulness and success of NIV were assessed in a prospective, observational registry of patients with influenza A (H1N1) virus pneumonia in 148 Spanish intensive care units (ICUs) in 2009-10. Significant variables for NIV success were included in a multivariate analysis. In all, 685 patients with confirmed influenza A (H1N1)v viral pneumonia were admitted to participating ICUs; 489 were ventilated, 177 with NIV. The NIV was successful in 72 patients (40.7%), the rest required intubation. Low Acute Physiology and Chronic Health Evaluation (APACHE) II, low Sequential Organ Failure Assessment (SOFA) and absence of renal failure were associated with NIV success. Success of NIV was independently associated with fewer than two chest X-ray quadrant opacities (OR 3.5) and no vasopressor requirement (OR 8.1). However, among patients with two or more quadrant opacities, a SOFA score ≤7 presented a higher success rate than those with SOFA score >7 (OR 10.7). Patients in whom NIV was successful required shorter ventilation time, shorter ICU stay and hospital stay than NIV failure. In patients in whom NIV failed, the delay in intubation did not increase mortality (26.5% versus 24.2%). Clinicians used NIV in 25.8% of influenza A (H1N1)v viral pneumonia admitted to ICU, and treatment was effective in 40.6% of them. NIV success was associated with shorter hospital stay and mortality similar to non-ventilated patients. NIV failure was associated with a mortality similar to those who were intubated from the start.