The use of noninvasive pressure support ventilation for severe respiratory insufficiency due to pulmonary oedema

Outcome of patients with acute heart failure secondary to acute myocardial infarction treated with noninvasive mechanical ventilation

INTRODUCTION AND OBJECTIVES

Noninvasive ventilation (NIV) has been shown to reduce the rate of endotracheal intubation and mortality in patients with acute heart failure (AHF). However, patients with AHF secondary to acute coronary syndrome/acute myocardial infarction (ACS-AMI) have been excluded from many clinical trials. The purpose of this study was to compare the effectiveness of NIV between patients with AHF triggered by ACS-AMI and by other etiologies.

METHODS

Prospective cohort study of all patients with AHF treated with NIV admitted to the intensive care unit for a period of 20 years. Patients were divided according to whether they had ACS-AMI as the cause of the AHF episode. NIV failure was defined as the need for endotracheal intubation or death.

RESULTS

A total of 1009 patients were analyzed, 403 (40%) showed ACS-AMI and 606 (60%) other etiologies. NIV failure occurred in 61 (15.1%) in the ACS-AMI group and in 64 (10.6%) in the other group (P=.031), without differences in in-hospital mortality (16.6% and 14.9%, respectively; P=.478).

CONCLUSIONS

The presence of ACS-AMI as the triggering cause of AHF did not influence patients with acute respiratory failure requiring noninvasive respiratory support.

Difficult Extubation: Calming the Sympathetic Storm

Tracheal extubation can evoke an equally strong haemodyamic stress response as tracheal intubation. We present a patient with myocardial infarction who repeatedly failed tracheal extubation. He developed acute pulmonary oedema following each attempt at tracheal extubation due to sympathetic overactivity. A change of approach with extubation under propofol sedation followed by continued sympatholysis with dexmedetomidine infusion allowed successful extubation.

Acute Effects of Positive Airway Pressure on Functional Mitral Regurgitation in Patients with Systolic Heart Failure

Background: Acute effects of positive airway pressure (PAP) [including continuous PAP (CPAP) and adaptive servo-ventilation, an advanced form of bi-level PAP] on functional mitral regurgitation (fMR) in patients with heart failure (HF) with left ventricular (LV) systolic dysfunction remain unclear. Thus, whether PAP therapy reduces fMR in such patients with HF was investigated. Methods and Results: Twenty patients with HF and LV systolic dysfunction defined as LV ejection fraction (LVEF) <50% (14 men; mean LVEF, 35.0 ± 11.5%) with fMR underwent echocardiography during 10-min CPAP (4 and 8 cm H₂O) and adaptive servo-ventilation. For fMR assessment, MR jet area fraction, defined as the ratio of MR jet on color Doppler to the left atrial area, was measured. The forward stroke volume (SV) index (fSVI) was calculated from the time-velocity integral, cross-sectional area of the aortic annulus, and body surface area. fMR significantly reduced on CPAP at 8 cm H₂O (0.30 ± 0.12) and adaptive servo-ventilation (0.29 ± 0.12), compared with the baseline phase (0.37 ± 0.12) and CPAP at 4 cm H₂O (0.34 ± 0.12) (P < 0.001). The fSVI did not change in any of the PAP sessions (P = 0.888). However, significant differences in fSVI responses to PAP were found between sexes (P for interaction, 0.006), with a significant reduction in fSVI in women (P = 0.041) and between patients with baseline fSVI ≥ and < the median value (27.8 ml/m², P for interaction, 0.018), with a significant fSVI reduction in patients with high baseline fSVI (P = 0.028). In addition, significant differences were found in fSVI responses to PAP between patients with LV end-systolic volume (LVESV) index ≥ and < the median value (62.0 ml/m², P for interaction, 0.034), with a significant fSVI increase in patients with a high LVESV index (P = 0.023). Conclusion: In patients with HF, LV systolic dysfunction, and fMR, PAP can alleviate fMR without any overall changes in forward SV. However, MR alleviation due to PAP might be associated with a decrease in forward SV in women with high baseline SV, whereas MR alleviation due to PAP might be accompanied by increased forward SV in patients with a dilated LV.

Non-Invasive Mechanical Ventilation Versus Continuous Positive Airway Pressure Relating to Cardiogenic Pulmonary Edema in an Intensive Care Unit

BACKGROUND

To compare the application of non-invasive ventilation (NIV) versus continuous positive airway pressure (CPAP) in the treatment of patients with cardiogenic pulmonary edema (CPE) admitted to an intensive care unit (ICU).

METHODS

In a prospective, randomized, controlled study performed in an ICU, patients with CPE were assigned to NIV (n=56) or CPAP (n=54). Primary outcome was intubation rate. Secondary outcomes included duration of ventilation, length of ICU and hospital stay, improvement of gas exchange, complications, ICU and hospital mortality, and 28-day mortality. The outcomes were analyzed in hypercapnic patients (PaCO₂>45mmHg) with no underlying chronic lung disease.

RESULTS

Both devices led to similar clinical and gas exchange improvement; however, in the first 60min of treatment a higher PaO₂/FiO₂ ratio was observed in the NIV group (205±112 in NIV vs. 150±84 in CPAP, P=.02). The rate of intubation was similar in both groups (9% in NIV vs. 9% in CPAP, P=1.0). There were no differences in duration of ventilation, ICU and length of hospital stay. There were no significant differences in ICU, hospital and 28-d mortality between groups. In the hypercapnic group, there were no differences between NIV and CPAP.

CONCLUSIONS

Either NIV or CPAP are recommended in patients with CPE in the ICU. Outcomes in the hypercapnic group with no chronic lung disease were similar using NIV or CPAP.

Failure of Noninvasive Ventilation for De Novo Acute Hypoxemic Respiratory Failure: Role of Tidal Volume

OBJECTIVES

A low or moderate expired tidal volume can be difficult to achieve during noninvasive ventilation for de novo acute hypoxemic respiratory failure (i.e., not due to exacerbation of chronic lung disease or cardiac failure). We assessed expired tidal volume and its association with noninvasive ventilation outcome.

DESIGN

Prospective observational study.

SETTING

Twenty-four bed university medical ICU.

PATIENTS

Consecutive patients receiving noninvasive ventilation for acute hypoxemic respiratory failure between August 2010 and February 2013.

INTERVENTIONS

Noninvasive ventilation was uniformly delivered using a simple algorithm targeting the expired tidal volume between 6 and 8 mL/kg of predicted body weight.

MEASUREMENTS

Expired tidal volume was averaged and respiratory and hemodynamic variables were systematically recorded at each noninvasive ventilation session.

MAIN RESULTS

Sixty-two patients were enrolled, including 47 meeting criteria for acute respiratory distress syndrome, and 32 failed noninvasive ventilation (51%). Pneumonia (n = 51, 82%) was the main etiology of acute hypoxemic respiratory failure. The median (interquartile range) expired tidal volume averaged over all noninvasive ventilation sessions (mean expired tidal volume) was 9.8 mL/kg predicted body weight (8.1-11.1 mL/kg predicted body weight). The mean expired tidal volume was significantly higher in patients who failed noninvasive ventilation as compared with those who succeeded (10.6 mL/kg predicted body weight [9.6-12.0] vs 8.5 mL/kg predicted body weight [7.6-10.2]; p = 0.001), and expired tidal volume was independently associated with noninvasive ventilation failure in multivariate analysis. This effect was mainly driven by patients with PaO2/FIO2 up to 200 mm Hg. In these patients, the expired tidal volume above 9.5 mL/kg predicted body weight predicted noninvasive ventilation failure with a sensitivity of 82% and a specificity of 87%.

CONCLUSIONS

A low expired tidal volume is almost impossible to achieve in the majority of patients receiving noninvasive ventilation for de novo acute hypoxemic respiratory failure, and a high expired tidal volume is independently associated with noninvasive ventilation failure. In patients with moderate-to-severe hypoxemia, the expired tidal volume above 9.5 mL/kg predicted body weight accurately predicts noninvasive ventilation failure.

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.

Non-invasive positive pressure ventilation (CPAP or bilevel NPPV) for cardiogenic pulmonary oedema

BACKGROUND

This is an update of a systematic review previously published in 2008 about non-invasive positive pressure ventilation (NPPV). NPPV has been widely used to alleviate signs and symptoms of respiratory distress due to cardiogenic pulmonary oedema. NPPV prevents alveolar collapse and helps redistribute intra-alveolar fluid, improving pulmonary compliance and reducing the pressure of breathing.

OBJECTIVES

To determine the effectiveness and safety of NPPV in the treatment of adult patients with cardiogenic pulmonary oedema in its acute stage.

SEARCH METHODS

We searched the following databases on 20 April 2011: CENTRAL and DARE, (The Cochrane Library, Issue 2 of 4, 2011); MEDLINE (Ovid, 1950 to April 2011); EMBASE (Ovid, 1980 to April 2011); CINAHL (1982 to April 2011); and LILACS (1982 to April 2011). We also reviewed reference lists of included studies and contacted experts and equipment manufacturers. We did not apply language restrictions.

SELECTION CRITERIA

We selected blinded or unblinded randomised or quasi-randomised clinical trials, reporting on adult patients with acute or acute-on-chronic cardiogenic pulmonary oedema and where NPPV (continuous positive airway pressure (CPAP) or bilevel NPPV) plus standard medical care was compared with standard medical care alone.

DATA COLLECTION AND ANALYSIS

Two authors independently selected articles and abstracted data using a standardised data collection form. We evaluated study quality with emphasis on allocation concealment, sequence generation allocation, losses to follow-up, outcome assessors, selective outcome reporting and adherence to the intention-to-treat principle.

MAIN RESULTS

We included 32 studies (2916 participants), of generally low or uncertain risk of bias. Compared with standard medical care, NPPV significantly reduced hospital mortality (RR 0.66, 95% CI 0.48 to 0.89) and endotracheal intubation (RR 0.52, 95% CI 0.36 to 0.75). We found no difference in hospital length of stay with NPPV; however, intensive care unit stay was reduced by 1 day (WMD -0.89 days, 95% CI -1.33 to -0.45). Compared with standard medical care, we did not observe significant increases in the incidence of acute myocardial infarction with NPPV during its application (RR 1.24, 95% CI 0.79 to 1.95) or after (RR 0.70, 95% CI 0.11 to 4.26). We identified fewer adverse events with NPPV use (in particular progressive respiratory distress and neurological failure (coma)) when compared with standard medical care.

AUTHORS' CONCLUSIONS

NPPV in addition to standard medical care is an effective and safe intervention for the treatment of adult patients with acute cardiogenic pulmonary oedema. The evidence to date on the potential benefit of NPPV in reducing mortality is entirely derived from small-trials and further large-scale trials are needed.

The role of continuous positive airway pressure in acute cardiogenic edema with preserved left ventricular systolic function

OBJECTIVE

The objective of the study was to compare the effect of continuous positive airway pressure (CPAP) in patients with acute cardiogenic pulmonary edema (ACPE) with preserved or impaired left ventricular systolic function with regard to resolution time.

METHODS

In a prospective, preliminary observational cohort study, 18 patients with preserved left ventricular systolic function (group A) and 18 patients with systolic heart dysfunction (group B) with ACPE underwent CPAP (10 cmH(2)0) through a face mask with standard medical therapy after a morphologic echocardiographic investigation shortly before CPAP.

RESULTS

Resolution time did not differ significantly between the 2 groups of patients (64 +/- 25 minutes in diastolic group vs 80 +/- 33 minutes in systolic group). One patient in preserved left ventricular systolic function group required endotracheal intubation (not statistically significant). No patient died during hospital stay. Arterial blood gases improved after a trial of CPAP in both groups of patients.

CONCLUSIONS

The results of this preliminary study show that resolution time is not significantly different in patients with ACPE with preserved or impaired systolic function submitted to CPAP.

[Non-invasive ventilation]

Non-invasive ventilation (NIV) is a technique that delivers mechanical ventilation avoiding side effects and complications associated with endotracheal intubation and invasive mechanical ventilation. This technique has proved to be effective in different types of respiratory failure. In this article, the authors revise the advantages and limitations of NIV, interfaces used and indications in acute and acute-on-chronic respiratory failure.

Use of noninvasive positive-pressure ventilation in the emergency department

To optimize the successful use of noninvasive positive-pressure ventilation (NPPV) in the emergency department (ED), clinicians must acquire the necessary knowledge, experience, and skill in its proper application. The purpose of this article is to provide a concise but thorough review of the current state of knowledge relating to the proper application of NPPV pertaining to its use in the ED.

Noninvasive ventilation in acute cardiogenic pulmonary edema

PURPOSE OF REVIEW

Patients with acute pulmonary edema are often treated with noninvasive ventilation (NIV). There are essentially two modalities used in this setting: continuous positive airway pressure and bilevel pressure support ventilation. The clinical impact of these techniques and the subset of patients who can benefit from their application have not been definitely established.

RECENT FINDINGS

The main advantage of the use of NIV in patients with severe acute pulmonary edema is to avoid intubation by more effectively decreasing respiratory distress with respect to conventional oxygen therapy. These beneficial effects were demonstrated in three meta-analyses including nearly 900 patients. Although neither technique was superior to the other in the comparative analysis, a tendency to reduce hospital mortality was observed, which was statistically significant for continuous positive airway pressure. However, unpublished data from a large multicenter trial comparing both modalities of NIV to conventional treatment in emergency departments did not confirm these results. Recent research has pointed out a clear advantage when the treatment is initiated early in the prehospital setting.

SUMMARY

Although in acute pulmonary edema NIV is more effective in improving respiratory distress than conventional oxygen therapy and reduces the necessity of intubation, the subset of patients who can best benefit from these techniques in terms of mortality still warrant further investigation.

Noninvasive ventilation in adult liver transplantation

Noninvasive ventilation (NIV) has proven to be a safe and effective technique in the treatment of respiratory failure complicating various medical and surgical diseases. In recent years, a growing interest has emerged in its adoption for ventilatory assistance in immunocompromised patients, such as those undergoing bone marrow, liver, lung, cardiac, and kidney transplantation. Weaning from the ventilator after liver transplantation can take longer because of unsatisfactory gas exchange during various attempts of T-piece trials. Rapid extubation followed by an immediate NIV application should be considered in this setting to shorten and accelerate the weaning process in those recipients who do not completely fulfill the criteria for safe extubation. By adding the pressure support (PS) mode with a continuous positive end expiratory pressure (PEEP), NIV could prevent the loss of vital capacity and impede severe lung derecruitment following extubation. Clinical experience has shown that properly delivered NIV mostly benefits moderately dyspneic recipients in acute respiratory failure, while it appears less promising and efficient in patients ventilated for extended periods of time. It has proven safe and efficient mainly as (1) a tool to promote an early ventilatory discontinuation and extubation; (2) a prophylactic strategy for preventing postoperative pulmonary complications; and (3) a simple method to start with in cases of acute hypoxic and/or hypercapnic respiratory failure. The improvements in arterial hypoxemia, the decreased ventilatory demand provided with an inspiratory support, as well as the scarcity of hemodynamic repercussions are among the major benefits of this method.

Non-invasive positive pressure ventilation (CPAP or bilevel NPPV) for cardiogenic pulmonary edema

BACKGROUND

Non-invasive positive pressure ventilation (NPPV) has been widely used to alleviate signs and symptoms of respiratory distress due to cardiogenic pulmonary edema. NPPV prevents alveolar collapse and helps redistribute intra-alveolar fluid, improving pulmonary compliance and reducing the pressure of breathing.

OBJECTIVES

To determine the effectiveness and safety of NPPV in the treatment of adult patients with cardiogenic pulmonary edema.

SEARCH STRATEGY

We undertook a comprehensive search of the following databases in April 2005: CENTRAL, MEDLINE, EMBASE, CINAHL, DARE and LILACS. We also reviewed reference lists of included studies and contacted experts, equipment manufacturers, and the Cochrane Heart Group. We did not apply language restrictions.

SELECTION CRITERIA

We selected blinded or unblinded randomized or quasi-randomized clinical trials, reporting on adult patients with acute or acute-on-chronic cardiogenic pulmonary edema and where NPPV (continuous positive airway pressure (CPAP)) and/or bilevel NPPV plus standard medical care was compared with standard medical care alone.

DATA COLLECTION AND ANALYSIS

Two authors independently selected articles and abstracted data using a standardized data collection form. We evaluated study quality with emphasis on allocation concealment, adherence to the intention-to-treat principle and losses to follow-up.

MAIN RESULTS

We included 21 studies involving 1,071 participants. Compared to standard medical care, NPPV significantly reduced hospital mortality (RR 0.6, 95% CI 0.45 to 0.84) and endotracheal intubation (RR 0.53, 95% CI 0.34 to 0.83) with numbers needed to treat of 13 and 8, respectively. We found no difference in hospital length of stay with NPPV, however, intensive care unit stay was reduced by 1 day (WMD -1.07 days, 95% CI -1.60 to -0.53). Compared to standard medical care, we did not observe significant increases in the incidence of acute myocardial infarction with NPPV during (RR 1.24, 95% CI 0.79 to 1.95) or after (RR 0.82, 95% CI 0.09 to 7.54) its application.

AUTHORS' CONCLUSIONS

NPPV, especially CPAP, in addition to standard medical care is an effective and safe intervention for the treatment of adult patients with acute cardiogenic pulmonary edema.

Cardiopulmonary interactions in patients with heart failure

PURPOSE OF REVIEW

The purpose of this review was to summarize recent findings concerning the consequences of cardiopulmonary interactions in acute cardiogenic pulmonary edema, weaning from mechanical ventilation and fluid-responsiveness assessment by respiratory variations of stroke volume.

RECENT FINDINGS

The efficacy of continuous or bilevel positive airway pressure in patients with acute cardiogenic pulmonary edema was strongly suggested by two recent meta-analyses. There is growing evidence to suggest that weaning-induced cardiac dysfunction and acute cardiogenic pulmonary edema could explain a large amount of liberation failure from mechanical ventilation. Despite a potential role for echocardiography and plasma measurements of B-type natriuretic peptide in demonstrating a cardiac origin to weaning failure, the demonstration of a significant increase in pulmonary-artery occlusion pressure during the weaning trial remains the gold standard for this purpose. In patients with heart failure there is no evidence for revisiting the reliability of the respiratory variation of stroke-volume surrogates to predict fluid responsiveness.

SUMMARY

For clinical practice, the knowledge of cardiopulmonary interactions is of paramount importance in understanding the crucial role of mechanical ventilation for treating patients with heart failure and, by contrast, the deleterious cardiovascular effects of weaning in patients with overt or hidden cardiac failure.

A comparison of continuous and bi-level positive airway pressure non-invasive ventilation in patients with acute cardiogenic pulmonary oedema: a meta-analysis

INTRODUCTION

We conducted the present study to investigate the potential beneficial and adverse effects of continuous positive airway pressure (CPAP) compared with bi-level positive airway pressure (BiPAP) noninvasive ventilation in patients with cardiogenic pulmonary oedema.

METHOD

We included randomized controlled studies comparing CPAP and BiPAP treatment in patients with cardiogenic pulmonary oedema from the Cochrane Controlled Trials Register (2005 issue 3), and EMBASE and MEDLINE databases (1966 to 1 December 2005), without language restriction. Two reviewers reviewed the quality of the studies and independently performed data extraction.

RESULTS

Seven randomized controlled studies, including a total of 290 patients with cardiogenic pulmonary oedema, were considered. The hospital mortality (relative risk [RR] 0.76, 95% confidence interval [CI] 0.32-1.78; P = 0.52; I2 = 0%) and risk for requiring invasive ventilation (RR 0.80, 95% CI 0.33-1.94; P = 0.62; I2 = 0%) were not significantly different between patients treated with CPAP and those treated with BiPAP. Stratifying studies that used either fixed or titrated pressure during BiPAP treatment and studies involving patients with or without hypercapnia did not change the results. The duration of noninvasive ventilation required until the pulmonary oedema resolved (weighted mean difference [WMD] in hours = 3.65, 95% CI -12.12 to +19.43; P = 0.65, I2 = 0%) and length of hospital stay (WMD in days = -0.04, 95% CI -2.57 to +2.48; P = 0.97, I2 = 0%) were also not significantly different between the two groups. Based on the limited data available, there was an insignificant trend toward an increase in new onset acute myocardial infarction in patients treated with BiPAP (RR 2.10, 95% CI 0.91-4.84; P = 0.08; I2 = 25.3%).

CONCLUSION

BiPAP does not offer any significant clinical benefits over CPAP in patients with acute cardiogenic pulmonary oedema. Until a large randomized controlled trial shows significant clinical benefit and cost-effectiveness of BiPAP versus CPAP in patients with acute cardiogenic pulmonary oedema, the choice of modality will depend mainly on the equipment available.

Efficacy and safety of non-invasive ventilation in the treatment of acute cardiogenic pulmonary edema--a systematic review and meta-analysis

INTRODUCTION

Continuous positive airway pressure ventilation (CPAP) and non-invasive positive pressure ventilation (NPPV) are accepted treatments in acute cardiogenic pulmonary edema (ACPE). However, it remains unclear whether NPPV is better than CPAP in reducing the need for endotracheal intubation (NETI) rates, mortality and other adverse events. Our aim was to review the evidence about the efficacy and safety of these two methods in ACPE management.

METHODS

We conducted a systematic review and meta-analysis of randomized controlled trials on the effect of CPAP and/or NIPV in the treatment of ACPE, considering the outcomes NETI, mortality and incidence of acute myocardial infarction (AMI). We searched six electronic databases up to May 2005 without language restrictions, reviewed references of relevant articles, hand searched conference proceedings and contacted experts.

RESULTS

Of 790 articles identified, 17 were included. In a pooled analysis, 10 studies of CPAP compared to standard medical therapy (SMT) showed a significant 22% absolute risk reduction (ARR) in NETI (95% confidence interval (CI), -34% to -10%) and 13% in mortality (95%CI, -22% to -5%). Six studies of NPPV compared to SMT showed an 18% ARR in NETI (95%CI, -32% to -4%) and 7% in mortality (95%CI, -14% to 0%). Seven studies of NPPV compared to CPAP showed a non-significant 3% ARR in NETI (95%CI, -4% to 9%) and 2% in mortality (95%CI, -6% to 10%). None of these methods increased AMI risk. In a subgroup analysis, NPPV did not lead to better outcomes than CPAP in studies including more hypercapnic patients.

CONCLUSION

Robust evidence now supports the use of CPAP and NPPV in ACPE. Both techniques decrease NETI and mortality compared to SMT and none shows increased AMI risk. CPAP should be considered a first line intervention as NPPV did not show a better efficacy, even in patients with more severe conditions, and CPAP is cheaper and easier to implement in clinical practice.

Noninvasive positive pressure ventilation in the intensive care unit: A concise review

OBJECTIVE

To critically assess available high-level clinical studies regarding use of noninvasive positive pressure ventilation in varied intensive care unit settings.

DATA SOURCE

Search of pertinent articles within Ovid MEDLINE from 1975 to 2005, CINAHL from 1982 to 2005, EMBASE from 1988 to 2005, and Web of Science from 1993 to 2005.

STUDY SELECTION

Randomized, controlled clinical trials and cohort studies and observational studies the authors consider important or novel.

DATA EXTRACTION/SYNTHESIS

Performed equally by both authors with the use of an Excel data spreadsheet.

CONCLUSION

There is abundant level I evidence supporting the use of noninvasive positive pressure ventilation in such critical care settings as acute hypercapnic respiratory failure, particularly related to chronic obstructive pulmonary disease, and acute cardiogenic pulmonary edema. We also report on other clinical scenarios in which the data may be somewhat less compelling, but evidence favors a noninvasive positive pressure ventilation trial. Some well designed studies suggest that noninvasive positive pressure ventilation is not an appropriate intervention for patients who have failed endotracheal extubation.

Noninvasive pressure support ventilation vs. continuous positive airway pressure in acute hypercapnic pulmonary edema

OBJECTIVE

This study compared noninvasive pressure support ventilation (NIPSV) and continuous positive airway pressure (CPAP) in patients with acute hypercapnic pulmonary edema with regard to resolution time.

DESIGN AND SETTING

Randomized prospective study in an emergency department.

PATIENTS AND PARTICIPANTS

We randomly assigned 36 patients with respiratory failure due to acute pulmonary edema and arterial hypercapnia (PaCO(2) >45 mmHg) to NIPSV (n=18) or CPAP through a face mask (n=18).

MEASUREMENTS AND RESULTS

Electrocardiographic and physiological measurements were made over 36 h. There was no difference in resolution time defined as clinical improvement with a respiratory rate of fewer than 30 breaths/min and SpO(2)of 96% or more between CPAP and NIPSV groups. Arterial carbon dioxide tension was significantly decreased after 1 h of ventilation (CPAP, 60.5+/-13.6 to 42.8+/-4.9 mmHg; NIPSV, 65.7+/-13.6 to 44.0+/-5.5 mmHg); respective improvements were seen in pH (CPAP, 7.22+/-0.11 to 7.37+/-0.04; NIPSV, 7.19+/-0.11 to 7.38+/-0.04), SpO(2) (CPAP, 86.9+/-3.7% to 95.1+/-2.6%; NIPSV, 83.7+/-6.6% to 96.0+/-2.9%), and respiratory rate (CPAP, 37.9+/-4.5 to 21.3+/-5.1 breaths/min; NIPSV, 39.8+/-4.4 to 21.2+/-4.6 breaths/min). No significant differences were seen with regards to endotracheal intubation and in-hospital mortality.

CONCLUSIONS

NIPSV proved as effective as CPAP in the treatment of patients with acute pulmonary edema and hypercapnia but did not improve resolution time.

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

BACKGROUND AND OBJECTIVE

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

PATIENTS AND METHOD

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

RESULTS

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

CONCLUSIONS

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

Myocardial infarction rate in acute pulmonary edema: noninvasive pressure support ventilation versus continuous positive airway pressure

OBJECTIVE

Noninvasive pressure support ventilation (NIPSV) delivered by face mask has proved an effective treatment for patients with acute pulmonary edema. However, an increase in acute myocardial infarction rate has been reported with this ventilation modality. We investigated whether the use of NIPSV increases the incidence of acute myocardial infarction compared with continuous positive airway pressure (CPAP) in patients with acute pulmonary edema.

DESIGN

Randomized, prospective, controlled study.

SETTING

Emergency Department, Niguarda Hospital of Milano (Italy).

PATIENTS

Forty-six patients affected by acute pulmonary edema.

INTERVENTIONS

The patients received either NIPSV (24 patients) or CPAP (22 patients) through a face mask.

MEASUREMENTS AND MAIN RESULTS

Cardiac enzymes (myoglobin, creatine kinase isoenzyme MB, and troponin I) were determined and electrocardiographic and physiologic measurements made over the subsequent 36 hrs. No significant differences were observed in the incidence of acute myocardial infarction in the CPAP group (13.6%) compared with the NIPSV group (8.3%). Both modalities of noninvasive ventilation improved ventilation and vital signs in patients with acute pulmonary edema. Two patients of the NIPSV group (8.3%) and one of the CPAP group (4.5%) required endotracheal intubation because vital signs and arterial blood gases worsened 1 hr after the start of noninvasive ventilation. No significant differences were found in in-hospital mortality rate.

CONCLUSIONS

NIPSV proved to be equally effective in improving vital signs and ventilation without increasing acute myocardial infarction rate in patients with nonischemic acute pulmonary edema in comparison to CPAP alone. However, because the study lacked statistical power and excluded patients with acute coronary syndromes, caution is still advised when applying NIPSV to the latter subgroup of patients.

Noninvasive ventilation in cardiogenic pulmonary edema: a multicenter randomized trial

Studies employing noninvasive pressure support ventilation in cardiogenic pulmonary edema have been performed in the intensive care unit when overt respiratory failure is already present and in small groups of patients. In this multicenter study, performed in emergency departments, 130 patients with acute respiratory failure were randomized to receive medical therapy plus O2 (65 patients) or noninvasive pressure support ventilation (65 patients). The primary end point was the need for intubation; secondary end points were in-hospital mortality and changes in some physiological variables. Noninvasive pressure support ventilation improved PaO2/FIO2, respiratory rate, and dyspnea significantly faster. Intubation rate, hospital mortality, and duration of hospital stay were similar in the two groups. In the subgroup of hypercapnic patients noninvasive pressure support ventilation improved PaCO2 significantly faster and reduced the intubation rate compared with medical therapy (2 of 33 versus 9 of 31; p=0.015). Adverse events, including myocardial infarction, were evenly distributed in the two groups. We conclude that during acute respiratory failure due to cardiogenic pulmonary edema the early use of noninvasive pressure support ventilation accelerates the improvement in PaO2/FIO2, PaCO2, dyspnea, and respiratory rate, but does not affect the overall clinical outcome. Noninvasive pressure support ventilation does, however, reduce the intubation rate in the subgroup of hypercapnic patients.

Risk factors for intubation as a guide for noninvasive ventilation in patients with severe acute cardiogenic pulmonary edema

OBJECTIVE

Noninvasive ventilation may reduce the endotracheal intubation rate in patients with acute cardiogenic pulmonary edema. However, criteria for selecting candidates for this technique are not well established. We analyzed a cohort of patients with severe acute cardiogenic pulmonary edema managed by conventional therapy to identify risk factors for intubation. These factors were used as guide for indications for noninvasive ventilation.

DESIGN AND SETTING

Observational cohort registry in the ICU and emergency and cardiology departments in a community teaching hospital.

PATIENTS

. 110 consecutive patients with acute cardiogenic pulmonary edema, 80 of whom received conventional oxygen therapy.

INTERVENTIONS

Physiological measurements and blood gas samples registered upon admission.

MEASUREMENTS AND RESULTS

Twenty-one patients (26%) treated with conventional oxygen therapy needed intubation. Acute myocardial infarction, pH below 7.25, low ejection fraction (<30%), hypercapnia, and systolic blood pressure below 140 mmHg were independent predictors for intubation. Conversely, systolic blood pressure of 180 mmHg or higher showed to be a protective factor since only two patients with this blood pressure value required intubation (8%)], both presenting with a pH lower than 7.25. Considering systolic blood pressure lower than 180 mmHg, patients who showed hypercapnia presented a high intubation rate (13/21, 62%) whereas the rate of intubation in patients with normocapnia was intermediate (6/23, 26%). All normocapnic patients with pH less than 7.25 required intubation. No patient with hypocapnia was intubated regardless the level of blood pressure.

CONCLUSIONS

Patients with pH less than 7.25 or systolic blood pressure less than 180 mmHg associated with hypercapnia should be promptly considered for noninvasive ventilation. With this strategy about 40% of the patients would be initially treated with this technique, which would involve nearly 90% of the patients that require intubation.

Boussignac continuous positive airway pressure device in the emergency care of acute cardiogenic pulmonary oedema: a randomized pilot study

This study aimed to assess the short-term respiratory effects of a new portable device that delivers a continuous positive airway pressure via a face mask (Boussignac-CPAP) in patients with severe acute cardiogenic pulmonary oedema, and the feasibility of using this technique in an emergency department. We prospectively studied 30 consecutive patients with acute cardiogenic pulmonary oedema. They were randomly assigned either to the Boussignac-CPAP valve, which delivered oxygen, or to standard oxygen delivery for a duration of 30 min. The end-expiratory pressure reached 9.3+/-0.3 cm H2O with the Boussignac-CPAP valve. At the end of the 30 min period, the decreases in respiratory rate and muscular activity were significantly greater among patients assigned to the Boussignac-CPAP valve compared with those on standard oxygen delivery [24+/-1.6 breaths/min, median 24 (15-37) versus 28.5+/-1.9, median 27 (16-38) and 1.3+/-0.2, median 1 (0-4) versus 2.7+/-0.3, median 2 (0-4), respectively]. Moreover, the arterial oxygen tension to inspired oxygen concentration ratio and tidal volume were improved at the end of the 30 min Boussignac-CPAP period compared with baseline. Boussignac-CPAP was easily implemented and no side-effects were reported. Continuous positive pressure delivered using the Boussignac-CPAP device is feasible in an emergency care setting. It can quickly improve respiratory distress in acute cardiogenic pulmonary oedema patients. A larger trial should be initiated in such an emergency care setting to demonstrate the effectiveness of the Boussignac-CPAP device.

Acute applications of noninvasive positive pressure ventilation

Noninvasive positive-pressure ventilation (NPPV) has been used increasingly to treat acute respiratory failure (ARF). The best indications for its use are ARF in patients with COPD exacerbations, acute pulmonary edema, and immunocompromised states. For these indications, multiple controlled trials have demonstrated that therapy with NPPV avoids intubation and, in the case of COPD and immunocompromised patients, reduces mortality as well. NPPV is used to treat patients with numerous other forms of ARF, but the evidence is not as strong for its use in those cases, and patients must be selected carefully. The best candidates for NPPV are able to protect their airway, are cooperative, and are otherwise medically stable. Success is optimized when a skilled team applies a well-fitted, comfortable interface. Ventilator settings should be adjusted to reduce respiratory distress while avoiding excessive discomfort, patient-ventilator synchrony should be optimized, and adequate oxygenation should be assured. The appropriate application of NPPV in the acute care setting should lead to improved patient outcomes and more efficient resource utilization.

Short-term noninvasive pressure support ventilation prevents ICU admittance in patients with acute cardiogenic pulmonary edema

STUDY OBJECTIVES

Noninvasive ventilation, although effective as treatment for patients with acute cardiogenic pulmonary edema when prolonged for hours, is of limited use in the emergency department (ED). The aim of the study was to determine whether a short attempt at noninvasive pressure support ventilation avoids ICU admittance and to identify lack of response prediction variables.

DESIGN

Prospective inception cohort study.

SETTING

ED of a university hospital.

PATIENTS

Fifty-eight consecutive patients with cardiogenic pulmonary edema who had been unresponsive to medical treatment and were admitted between January 1999 and December 2000.

INTERVENTIONS

Pressure support ventilation was instituted through a full-face mask until the resolution of respiratory failure. A 15-min "weaning test" was performed to evaluate clinical stability. Responder patients were transferred to a medical ward. Nonresponding patients were intubated and were admitted to the ICU.

MAIN OUTCOME MEASURES

The included optimal length of intervention, the avoidance of ICU admittance, the incidence of myocardial infarction, and predictive lack of response criteria.

RESULTS

Patients completed the trial (mean [+/- SD] duration, 96 +/- 40 min). None of the responders (43 patients; 74%) was subsequently ventilated or was admitted to the ICU. Two new episodes of myocardial infarction were observed. Thirteen of 58 patients died. A mean arterial pressure of < 95 mm Hg (odds ratio [OR], 10.6; 95% confidence interval [CI], 1.8 to 60.8; p < 0.01) and COPD (OR, 9.4; 95% CI, 1.6 to 54.0; p < 0.05) at baseline predicted the lack of response to noninvasive ventilation.

CONCLUSIONS

A short attempt at noninvasive ventilation is effective in preventing invasive assistance. A 15-min weaning test can identify patients who will not need further invasive ventilatory support. COPD and hypotension at baseline are negative predictive criteria.

Effectiveness of non-invasive positive pressure ventilation differs between decompensated chronic restrictive and obstructive pulmonary disease patients

OBJECTIVE

To compare the efficiency of non-invasive positive pressure ventilation (NPPV) in decompensated patients with either chronic obstructive pulmonary disease (COPD) or chronic restrictive pulmonary disease.

DESIGN

Retrospective study.

SETTING

A 17-bed intensive care unit in a university teaching hospital.

SETTING

Sixty-four patients with COPD (age: 70+/-13 years, sex ratio: 37 male to 27 female patients, forced expiratory volume in 1 s: 31+/-13% predicted) and 20 patients with chronic restrictive pulmonary disease (age: 75+/-9 years, sex ratio: 9 male to 11 female patients, total lung capacity: 57+/-17% predicted) consecutively treated with NPPV (facial mask, pressure support ventilation (PSV) +/- PEEP) for acute respiratory failure.

MEASUREMENTS AND RESULTS

There were no statistically significant differences between COPD and patients with chronic restrictive pulmonary disease in terms of cause of exacerbation, use of oxygen therapy or NPPV at home, severity of acute respiratory failure (ARF), mean delay from intensive care admission to initiation of NPPV and total duration of NPPV. Patients with chronic restrictive pulmonary disease had a lower success rate on NPPV (without need of tracheal intubation) than COPD (35% vs 67%, p=0.01). Causes of NPPV failure were not different between COPD and patients with restrictive disease. After 12 h of NPPV, restrictive patients who succeeded with NPPV had similar respiratory rate, minute ventilation and arterial blood gas to COPD patients. At the 3rd and 12th h of NPPV, improvements in pH and PaCO(2) were predictive of NPPV success in COPD, but not in restrictive patients.

CONCLUSION

The results of this retrospective study suggest that the effectiveness of NPPV for acute decompensation is less in patients with chronic restrictive pulmonary disease as compared to COPD.

[Noninvasive ventilation in the intensive care unit -- is it still negligible?]

Non-invasive positive pressure ventilation (NIPPV) has been discussed comprehensively in the last years, but usage of non-invasive ventilation in Intensive Care Units is rare. The reasons may be uncertainty in indications and difficulties in handling the masks and ventilators. In the last years the introduction of full face masks and respiratory helmets has made it possible to ventilate patients with unusual facial forms and to avoid problems of pressure necrosis. Software components designed for NIPPV are available for standard respirators. Indications for NIPPV (neuromuscular diseases, spinal abnormalities, chest wall malformations, COPD, cardiogenic pulmonary edema) have been ensured in clinical trials. No sufficient data are available for the application of NIPPV in weaning and respiratory failure following extubation. Indication for NIPPV becomes apparent when therapy starts in early stage with sufficient ventilation pressure. Compared to standard therapy, no reliable advantage has been seen for NIPPV in hypoxic hypercapnia respiratory failure except for malignant diseases. However, prophylactic use in patients with high risk might be conceivable. For these patients strict criteria of termination are required to avoid missing the time point for intubation. Gas exchange disturbances in advanced lung fibrosis, pneumonia and ARDS are not amenable to NIPPV. Contraindications for NIPPV are non-compliant patients, absence of cough- and pharyngeal reflexes as well as retention of secretions and malignant ventricular arrhythmia. Relative contraindications are catecholamine-dependent circulatory collapse and acute myocardial infarction, since sufficient data for NIPPV are missing.

Noninvasive mechanical ventilation in acute cardiogenic pulmonary edema

Acute cardiogenic pulmonary edema is a frequent life-threatening emergency. During the last 10 years, increasing attention has focused on the use of noninvasive ventilation to treat patients with various forms of acute respiratory failure. Numerous physiologic data and clinical studies support the use of noninvasive ventilation during cardiogenic pulmonary edema. Noninvasive ventilation results in rapid improvement of clinical signs of respiratory distress and gas exchange and decreases the need for endotracheal intubation for patients in the ICU with acute hypercapnic respiratory failure related to cardiogenic pulmonary edema. However, no sustained benefit (, decreased late mortality) or benefit for less severe forms of cardiogenic pulmonary edema has been demonstrated yet. Moreover, there are still few data that support the use of a specific mode of ventilation over the others.

The effect of bi-level positive airway pressure on postoperative pulmonary function following gastric surgery for obesity

The severely obese patient has varying degrees of intrinsic reduction of expiratory flow rates and lung volumes. Thus, the severely obese patient is predisposed to postoperative atelectasis, ineffective clearing of respiratory secretions, and other pulmonary complications. This study evaluated the effect of bi-level positive airway pressure (BiPAP) on pulmonary function in obese patients following open gastric bypass surgery Patients with a body mass index (BMI) of at least 40 kg/m2 who were undergoing elective gastric bypass were eligible to be randomized to receive either BiPAP during the first 24 h postoperatively or conventional postoperative care. Patients with significant cardiovascular and pulmonary diseases were excluded from the study. Forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1.0), peak expiratory flow rate (PEFR), and percent hemoglobin oxygen saturation (SpO2) were measured preoperatively, and on postoperative days 1, 2, and 3. Twenty-seven patients were entered in the study 14 received BiPAP and 13 received conventional postoperative care. There was no significant difference preoperatively between the study and control groups in regards to age, BMI, FVC, FEV1.0, PEFR or SpO2. Postoperatively expiratory flow was decreased in both groups. However, the FVC and FEV1.0 were significantly higher on each of the three consecutive postoperative days in the patients who received BiPAP therapy. The SpO2 was significantly decreased in the control group over the same time period. Prophylactic BiPAP during the first 12-24 h postoperatively resulted in significantly higher measures of pulmonary function in severely obese patients who had undergone elective gastric bypass surgery. These improved measures of pulmonary function, however, did not translate into fewer hospital days or a lower complication rate in our study population of otherwise healthy obese patients. Further study is necessary to determine if BiPAP therapy in the first 24 postoperative hours would be of benefit in severely obese patients with comorbid illnesses who have undergone elective gastric bypass.

Cardiac and respiratory effects of continuous positive airway pressure and noninvasive ventilation in acute cardiac pulmonary edema

OBJECTIVE

Continuous positive airway pressure (CPAP) is considered an effective nonpharmacologic method of treating patients with severe acute cardiogenic pulmonary edema. However, we hypothesized that bilevel noninvasive positive-pressure ventilation (NPPV), which combines both inspiratory pressure support and positive expiratory pressure, would unload the respiratory muscles and improve cardiac and hemodynamic function more effectively than CPAP.

DESIGN

Randomized crossover study.

SETTING

Critical care unit, Raymond Poincaré Hospital.

PATIENTS

Six consecutive patients with acute cardiogenic pulmonary edema.

INTERVENTIONS

Patients were sequentially treated with 5 cm H2O CPAP, 10 cm H2O CPAP, and NPPV in a random order.

MEASUREMENTS AND MAIN RESULTS

Cardiac and hemodynamic function and indexes of respiratory mechanics were measured at each treatment sequence. NPPV reduced the esophageal pressure swing and esophageal pressure-time product compared with baseline (p <.05). There was no reduction in esophageal pressure swing or esophageal pressure-time product with CPAP. NPPV and 10 cm H2O CPAP reduced the mean transmural right and left atrial filling pressures without a change in cardiac index.

CONCLUSIONS

This study demonstrates that NPPV was more effective at unloading the respiratory muscles than CPAP in acute cardiogenic pulmonary edema. In addition, NPPV and 10 cm H2O CPAP produced a reduction in right and left ventricular preload, which suggests an improvement in cardiac performance.

Noninvasive ventilation in acute respiratory failure--a meta-analysis update

OBJECTIVE

To present a meta-analytic update on the effects of noninvasive ventilation (NIV) in the management of acute respiratory failure.

DESIGN

Meta-analysis of randomized controlled clinical trials in acute respiratory failure comparing NIV with standard medical therapy.

PATIENTS

Randomized controlled trials of NIV in acute respiratory failure were identified by search of i) MEDLINE (1966-2000), ii) published abstracts from scientific meetings, and iii) bibliographies of relevant articles.

MEASUREMENTS AND MAIN RESULTS

Of the 15 randomized controlled trials that were identified (13 published and 2 in abstract form), 8 studies were on exacerbations of chronic obstructive pulmonary disease (COPD) and 7 on diverse disease processes in both COPD and non-COPD groups ("mixed-group"). Because of underlying heterogeneity of treatment effects, only the DerSimonian-Laird random effects estimator was used and reported. The effects of NIV vs. standard therapy on mortality and subsequent invasive mechanical ventilation (MV) was assessed as risk difference, and hospital length of stay as mean weighted difference (days). NIV was associated with reduction in mortality (8%, p = .03), reduced need for MV (19%, p = .001) and shortened hospital length of stay (2.74 days, p = .004). In the COPD cohort, significant reductions in mortality (13%, p = .001), need for MV (18%, p = .02), and hospital length of stay (5.66 days, p = .01) were observed in the group treated with NIV. In contrast, in the mixed-group, there was no demonstrable reduction in mortality (0%, p = .98). However, there was significant reduction in the need for MV (22%, p = .001). Publication bias was not evident on analysis. Treatment effect i) as mortality or need for mechanical ventilation was not modified by enrollment pH, PaCO2, nor age and ii) was not related (as log odds ratio) to underlying risk (control arm log odds). Cumulative meta-analysis did not demonstrate any substantial variation in the point estimates with the addition of the recently published studies. However a contraction in the confidence intervals was observed in the COPD subgroup. Complication rates were not significantly different in the standard medical therapy group and the NIV treated patients.

CONCLUSION

Substantial reductions in mortality and the need for subsequent MV were associated with NIV in acute respiratory failure, especially in the COPD subgroup. Hospital length of stay was variably affected. Heterogeneity of treatment effects was observed.

Noninvasive mechanical ventilation in acute hypoxaemic respiratory failure

In acute hypoxaemic respiratory failure (HRF), oxygenation, reduction in the work of breathing and in dyspnoea may be achieved by delivering noninvasive mechanical ventilation (NIMV). Several uncontrolled and 13 randomized controlled studies (RCS) were reviewed. Uncontrolled studies confirmed the feasibility and the possibility to improve arterial blood oxygenation with NIMV. The 13 RCS compared NIMV versus a conventional approach in a total of 720 patients with HRF. Endotracheal intubation was required in 186 of the 358 patients (median (95% confidence interval (CI)) 51%, (40-63%)) assigned to a conventional approach and in 107 of the 362 patients (29% (20-39%)) assigned to NIMV. Eleven of the 13 RCS found a reduction in the rate of endotracheal intubation with NIMV with an absolute risk reduction of 31% (30-33%). Ten of the 13 RCS found a reduction in the mortality rate which was 30% (19-40%) in the control group and 19% (13-26%) in the NIMV group. The mean absolute risk reduction was 15% (10-20%). In conclusion, noninvasive ventilation appears to be a useful method in avoiding endotracheal intubation and probably in reducing the morbidity of patients with hypoxaemic respiratory failure.

[Characteristics of acute myocardial infarction patients treated with mechanical ventilation. Data from the ARIAM Registry]

INTRODUCTION

Scarce information is available about the use, clinical course and follow-up of patients with acute myocardial infarction treated with mechanical ventilation.

PATIENTS AND METHOD

Historical cohort study of patients with acute myocardial infarction, included in Spanish registry ARIAM. Differences in clinical characteristics and prognosis from patients treated with or without mechanical ventilation were compared.

RESULTS

Three hundred and thirty-three of the 4143 patients (8.1%) with acute myocardial infarction were treated with mechanical ventilation. Treated patients were older, more frequently female, and had more frequently reinfarcts, anterior infarction, Killip III and IV, and higher creatine phosphokinase peak. Diabetes and high blood pressure were more frequent in those in which the technique was applied. They had a higher mortality at the coronary care unit (65.7 vs 5.1%; p < 0.001) than the non-ventilated patients. In multivariate analysis, creatine phosphokinase peak levels higher than 1.200 units/ml, Killip III and IV, and an infarction localization different to inferior were independent predictors of mechanical ventilation application. The 220 treated patients who died were older, more frequently female, had been more frequently admitted to the coronary unit, and had Killip IV whereas Killip III was more frequent among survivors. In multivariate analysis, restricted to patients treated with mechanical ventilation, Killip III was an independent predictor of survival with an odds ratio for mortality of 0.26 (CI 95%: 0.09-0.77).

CONCLUSIONS

Mechanical ventilation is a vital support technique employed in a significant number of complicated acute myocardial infarction patients. The high mortality of these patients was related to more extended myocardial infarction and a worse clinical state.

Evaluation and management of acutely decompensated chronic heart failure in the emergency department

A wide range of patients with symptomatic heart failure seek treatment in the emergency department. While there is no single approach to the diversity of patients with acutely decompensated heart failure, certain overarching principles apply. For patients with acute pulmonary edema or cardiogenic shock, the first priority must be rapid stabilization and treatment of reversible problems. For patients with less dramatic presentations, a more systematic search for precipitating factors may be required. Therapy, in general, is directed at reversing dyspnea and/or hypoxemia caused by pulmonary edema, improving systemic perfusion, and reducing myocardial oxygen demand. While morphine and diuretics still have their traditional roles, vasodilators and inotropic agents play an increasingly important part in the modern pharmacologic approach to decompensated heart failure in the emergency department. After evaluation and stabilization in the emergency department, most patients will require hospital admission, although a subset of low-risk patients may be appropriate for discharge to home following a period of observation. Strategies to optimize emergency department care are likely to have an impact upon patient outcomes and upon resource utilization. (c)2001 by CHF, Inc.

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

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

Non-invasive pressure support ventilation versus conventional oxygen therapy in acute cardiogenic pulmonary oedema: a randomised trial

BACKGROUND

Non-invasive pressure support ventilation (NIPSV) is an effective treatment for acute respiratory failure in patients with chronic obstructive pulmonary disease. We assessed the efficacy of this therapy in acute cardiogenic pulmonary oedema in a randomised comparison with conventional oxygen therapy.

METHODS

40 patients were randomly assigned conventional oxygen therapy or NIPSV supplied by a standard ventilator through a face mask, with adjustment of tidal volume and pressure support in addition to a positive end-expiratory pressure of 5 cm water. Physiological measurements were obtained in the first 2 h and at 3 h, 4 h, and 10 h. The main endpoints were intubation rate and resolution time. Analyses were by intention to treat.

FINDINGS

Three patients were withdrawn on the basis of clinical and chest radiography results. Endotracheal intubation was required in one (5%) of 19 patients assigned NIPSV and in six (33%) of 18 assigned conventional oxygen therapy (p=0.037). Resolution time (defined as a clinical improvement with oxygen saturation of 96% or more and respiratory rate less than 30 breaths/min) was significantly shorter in the NIPSV group (median 30 [IQR 15-53] vs 105 [50-230] min, p=0.002). NIPSV led to a rapid improvement in oxygenation in the first 2 h. There were no differences in hospital length of stay or mortality.

INTERPRETATION

In this study of acute cardiogenic pulmonary oedema, NIPSV was superior to conventional oxygen therapy. Further studies should compare NIPSV with continuous positive airway pressure.