Natriuretic peptides

Natriuretic peptides (NPs) are released from the heart in response to pressure and volume overload. B-type natriuretic peptide (BNP) and N-terminal-proBNP have become important diagnostic tools for assessing patients who present acutely with dyspnea. The NP level reflects a compilation of systolic and diastolic function as well as right ventricular and valvular function. Studies suggest that using NPs in the emergency department can reduce the consumption of hospital resources and can lower costs by either eliminating the need for other, more expensive tests or by establishing an alternative diagnosis that does not require hospital stay. Caveats such as body mass index and renal function must be taken into account when analyzing NP levels. Natriuretic peptide levels have important prognostic value in multiple clinical settings, including in patients with stable coronary artery disease and with acute coronary syndromes. In patients with decompensated heart failure due to volume overload, a treatment-induced drop in wedge pressure is often accompanied by a rapid drop in NP levels. Knowing a patient's NP levels might thus assist with hemodynamic assessment and subsequent treatment titration. Monitoring NP levels in the outpatient setting might also improve patient care and outcomes.

Treatment of severe cardiogenic pulmonary edema with continuous positive airway pressure delivered by face mask

BACKGROUND

Severe cardiogenic pulmonary edema is a frequent cause of respiratory failure, and many patients with this condition require endotracheal intubation and mechanical ventilation. We investigated whether continuous positive airway pressure delivered by means of a face mask had physiologic benefit and would reduce the need for intubation and mechanical ventilation.

METHODS

We randomly assigned 39 consecutive patients with respiratory failure due to severe cardiogenic pulmonary edema to receive either oxygen alone or oxygen plus continuous positive airway pressure delivered through a face mask. It was not possible to blind the investigators to the assigned treatment. Physiologic measurements were made over the subsequent 24 hours, and the patients were followed to hospital discharge.

RESULTS

After 30 minutes, both respiratory rate and arterial carbon dioxide tension had decreased more in the patients who received oxygen plus continuous positive airway pressure. The mean (+/- SD) respiratory rate at 30 minutes decreased from 32 +/- 6 to 33 +/- 9 breaths per minute in the patients receiving oxygen alone and from 35 +/- 8 to 27 +/- 6 breaths per minute in those receiving oxygen plus continuous positive airway pressure (P = 0.008); the arterial carbon dioxide tension decreased from 64 +/- 17 to 62 +/- 14 mm Hg in those receiving oxygen alone and from 58 +/- 8 to 46 +/- 4 mm Hg in those receiving oxygen plus continuous positive airway pressure (P less than 0.001). The patients receiving continuous positive airway pressure also had a greater increase in the arterial pH (oxygen alone, from 7.15 +/- 0.11 to 7.18 +/- 0.18; oxygen plus continuous positive airway pressure, from 7.18 +/- 0.08 to 7.28 +/- 0.06; P less than 0.001) and in the ratio of arterial oxygen tension to the fraction of inspired oxygen (oxygen alone, from 136 +/- 44 to 126 +/- 47; oxygen plus continuous positive airway pressure, from 138 +/- 32 to 206 +/- 126; P = 0.01). After 24 hours, however, there were no significant differences between the two treatment groups in any of these respiratory indexes. Seven (35 percent) of the patients who received oxygen alone but none who received oxygen plus continuous positive airway pressure required intubation and mechanical ventilation (P = 0.005). However, no significant difference was found in in-hospital mortality (oxygen alone, 4 of 20 patients; oxygen plus continuous positive airway pressure, 2 of 19; P = 0.36) or the length of the hospital stay.

CONCLUSIONS

Continuous positive airway pressure delivered by face mask in patients with severe cardiogenic pulmonary edema can result in early physiologic improvement and reduce the need for intubation and mechanical ventilation. This short-term study could not establish whether continuous positive airway pressure has any long-term benefit or whether a larger study would have shown a difference in mortality between the treatment groups.

Randomised trial of high-dose isosorbide dinitrate plus low-dose furosemide versus high-dose furosemide plus low-dose isosorbide dinitrate in severe pulmonary oedema

BACKGROUND

Nitrates and furosemide, commonly administered in the treatment of pulmonary oedema, have not been compared in a prospective clinical trial. We compared the efficacy and safety of these drugs in a randomised trial of patients with severe pulmonary oedema and oxygen saturation below 90%.

METHODS

Patients presenting to mobile emergency units with signs of congestive heart failure were treated with oxygen 10 L/min, intravenous furosemide 40 mg, and morphine 3 mg bolus. 110 patients were randomly assigned either to group A, who received isosorbide dinitrate (3 mg bolus administered intravenously every 5 min; n=56) or to group B, who received furosemide (80 mg bolus administered intravenously every 15 min, as well as isosorbide dinitrate 1 mg/h, increased every 10 min by 1 mg/h; n=54). Six patients were withdrawn on the basis of chest radiography results. Treatment was continued until oxygen saturation was above 96% or mean arterial blood pressure had decreased by 30% or to below 90 mm Hg. The main endpoints were death, need for mechanical ventilation, and myocardial infarction. The analyses were by intention to treat.

FINDINGS

Mechanical ventilation was required in seven (13%) of 52 group-A patients and 21 (40%) of 52 group-B patients (p=0.0041). Myocardial infarction occurred in nine (17%) and 19 (37%) patients, respectively (p=0.047). One patient in group A and three in group B died (p=0.61). One or more of these endpoints occurred in 13 (25%) and 24 (46%) patients, respectively (p=0.041).

INTERPRETATION

High-dose isosorbide dinitrate, given as repeated intravenous boluses after low-dose intravenous furosemide, is safe and effective in controlling severe pulmonary oedema. This treatment regimen is more effective than high-dose furosemide with low-dose isosorbide nitrate in terms of need for mechanical ventilation and frequency of myocardial infarction.

Intact epithelial barrier function is critical for the resolution of alveolar edema in humans

Within 15 min of endotracheal intubation, the resolution of pulmonary edema was studied over the next 12 h in 34 mechanically ventilated patients by (1) serial measurements of the alveolar-arterial oxygen difference, (2) the extent of edema on the initial and follow-up chest radiograph, and (3) by an initial and final measurement of total protein and albumin concentration in sequential samples of pulmonary edema fluid. Based on the oxygenation and chest radiographic data, 24 patients clinically improved and 10 patients did not improve. In the 10 patients who did not clinically improve (3, hydrostatic edema; 7, permeability edema), there was no change in the final edema fluid protein concentration (4.1 +/- 1.1 g/100 ml) compared with the initial edema fluid protein concentration (4.2 +/- 1.0 g/100 ml) (p = ns). However, in the 24 patients who clinically improved (15, hydrostatic edema; 9, permeability edema), there was an increase in every patient's final edema protein concentration (5.6 +/- 2.3 g/100 ml) compared with their initial edema protein concentration (3.8 +/- 1.2 g/100 ml) (p less than 0.01). In 13 of these 24 patients, the final edema fluid concentration (7.3 +/- 1.6 g/100 ml) exceeded the final plasma protein concentration (5.6 +/- 0.8 g/100 ml) by a mean value of 1.7 g/100 ml protein. The data provide the first evidence in humans to support the hypothesis that active ion transport across the alveolar epithelial barrier is the primary mechanism for clearance of edema fluid from the air spaces of the lung.(ABSTRACT TRUNCATED AT 250 WORDS)

Improved outcome based on fluid management in critically ill patients requiring pulmonary artery catheterization

We performed a randomized, prospective trial to evaluate whether fluid management that emphasized diuresis and fluid restriction in patients with pulmonary edema could affect the development or resolution of extravascular lung water (EVLW), as well as time on mechanical ventilation and time in the intensive care unit (ICU), in critically ill patients requiring pulmonary artery catheterization (PAC). PAC was performed on 101 patients. A total of 52 patients were randomized to an EVLW management group using a protocol based on bedside indicator-dilution measurements of EVLW. The other 49 patients were randomized to a wedge pressure (WP) management group in whom fluid management decisions were guided by WP measurements. A total of 89 patients had pulmonary edema (defined as EVLW greater than 7 ml/kg ideal body weight). Except for a clinically unimportant difference in mean age, the two groups were entirely comparable at baseline. The study groups were managed differently, as evidenced by cumulative input-output of 2,239 +/- 3,695 ml (median = 1,600 ml) in the WP group versus 142 +/- 3,632 ml (median = 754 ml) in the EVLW group (p = 0.001). EVLW decreased significantly, and ventilator-days and ICU days were significantly shorter only in patients from the EVLW group. No clinically significant adverse effect occurred as a result of following the EVLW group algorithm. Thus, a lower positive fluid balance, especially in patients with pulmonary edema regardless of cause, is associated with reduced EVLW, ventilator-days, and ICU days.

Noninvasive ventilation in acute cardiogenic pulmonary edema

BACKGROUND

Noninvasive ventilation (continuous positive airway pressure [CPAP] or noninvasive intermittent positive-pressure ventilation [NIPPV]) appears to be of benefit in the immediate treatment of patients with acute cardiogenic pulmonary edema and may reduce mortality. We conducted a study to determine whether noninvasive ventilation reduces mortality and whether there are important differences in outcome associated with the method of treatment (CPAP or NIPPV).

METHODS

In a multicenter, open, prospective, randomized, controlled trial, patients were assigned to standard oxygen therapy, CPAP (5 to 15 cm of water), or NIPPV (inspiratory pressure, 8 to 20 cm of water; expiratory pressure, 4 to 10 cm of water). The primary end point for the comparison between noninvasive ventilation and standard oxygen therapy was death within 7 days after the initiation of treatment, and the primary end point for the comparison between NIPPV and CPAP was death or intubation within 7 days.

RESULTS

A total of 1069 patients (mean [+/-SD] age, 77.7+/-9.7 years; female sex, 56.9%) were assigned to standard oxygen therapy (367 patients), CPAP (346 patients), or NIPPV (356 patients). There was no significant difference in 7-day mortality between patients receiving standard oxygen therapy (9.8%) and those undergoing noninvasive ventilation (9.5%, P=0.87). There was no significant difference in the combined end point of death or intubation within 7 days between the two groups of patients undergoing noninvasive ventilation (11.7% for CPAP and 11.1% for NIPPV, P=0.81). As compared with standard oxygen therapy, noninvasive ventilation was associated with greater mean improvements at 1 hour after the beginning of treatment in patient-reported dyspnea (treatment difference, 0.7 on a visual-analogue scale ranging from 1 to 10; 95% confidence interval [CI], 0.2 to 1.3; P=0.008), heart rate (treatment difference, 4 beats per minute; 95% CI, 1 to 6; P=0.004), acidosis (treatment difference, pH 0.03; 95% CI, 0.02 to 0.04; P<0.001), and hypercapnia (treatment difference, 0.7 kPa [5.2 mm Hg]; 95% CI, 0.4 to 0.9; P<0.001). There were no treatment-related adverse events.

CONCLUSIONS

In patients with acute cardiogenic pulmonary edema, noninvasive ventilation induces a more rapid improvement in respiratory distress and metabolic disturbance than does standard oxygen therapy but has no effect on short-term mortality. (Current Controlled Trials number, ISRCTN07448447.)

Pathophysiology of acute lung injury and the acute respiratory distress syndrome

Since the adult respiratory distress syndrome was first described substantial progress has been made in understanding the pathogenesis of this complex syndrome. This review summarizes our current understanding of the pathophysiology of what is now termed the acute respiratory distress syndrome (ARDS) and its less severe form acute lung injury (ALI), with an emphasis on cellular and molecular mechanisms of injury that may represent potential therapeutic targets. Although it is difficult to synthesize all of these abnormalities into a single, unified, pathogenetic pathway, a theme that emerges repeatedly is that of imbalance, be it between pro- and anti-inflammatory cytokines, oxidants and antioxidants, procoagulants and anticoagulants, neutrophil recruitment and activation and mechanisms of neutrophil clearance, or proteases and protease inhibitors. Future therapies aimed at restoring the overall balance of cytokines, oxidants, coagulants, and proteases may ultimately be successful where therapies that target individual cytokines or other mediators have not.

Balloon pulmonary angioplasty for treatment of chronic thromboembolic pulmonary hypertension

BACKGROUND

Although pulmonary thromboendarterectomy is increasingly successful for the definitive treatment of chronic thromboembolic pulmonary hypertension (CTEPH), not all patients have surgically accessible disease. Others are poor surgical candidates because of comorbid illness. Therefore, for selected patients, we defined and implemented an alternative interventional strategy of balloon pulmonary angioplasty (BPA).

METHODS AND RESULTS

Eighteen patients (mean age, 51.8 years; range, 14 to 75 years) with CTEPH underwent BPA; they averaged 2.6 procedures (range, 1 to 5) and 6 dilations (range, 1 to 12). Selection of pulmonary artery segments for dilation required (1) complete occlusion, (2) filling defects, or (3) signs of intravascular webs. After an average of 36 months of follow-up (range, 0.5 to 66 months), the average New York Heart Association class improved from 3.3 to 1.8 (P:<0.001), and 6-minute walking distances increased from 209 to 497 yards (P:<0.0001). Pulmonary artery mean pressures decreased from 43.0+/-12.1 to 33. 7+/-10.2 mm Hg (P:=0.007). Eleven patients developed reperfusion pulmonary edema; 3 required mechanical ventilation.

CONCLUSIONS

BPA reduces pulmonary artery hypertension in patients with CTEPH and is associated with long-term improvement in New York Heart Association class and 6-minute walking distances. BPA is a promising interventional technique that warrants randomized comparison with medical therapy in CTEPH patients who are not surgical candidates.

Clinical practice: Acute high-altitude illnesses

A 45-year-old healthy man wishes to climb Mount Kilimanjaro (5895 m) in a 5-day period, starting at 1800 m. The results of a recent exercise stress test were normal; he runs 10 km 4 or 5 times per week and finished a marathon in less than 4 hours last year. He wants to know how he can prevent becoming ill at high altitude and whether training or sleeping under normobaric hypoxic conditions in the weeks before the ascent would be helpful. What would you advise?

Randomized, prospective trial of bilevel versus continuous positive airway pressure in acute pulmonary edema

OBJECTIVE

To evaluate whether bilevel positive airway pressure, by actively assisting inhalation, more rapidly improves ventilation, acidemia, and dyspnea than continuous positive airway pressure (CPAP) in patients with acute pulmonary edema.

DESIGN

Randomized, controlled, double-blind trial.

SETTING

Emergency department in a university hospital.

PATIENTS

Twenty-seven patients, presenting with acute pulmonary edema, characterized by dyspnea, tachypnea, tachycardia, accessory muscle use, bilateral rales, and typical findings of congestion on a chest radiograph.

INTERVENTIONS

In addition to standard therapy, 13 patients were randomized to receive nasal CPAP (10 cm H2O), and 14 patients were randomized to receive nasal bilevel positive airway pressure (inspiratory and expiratory positive airway pressures of 15 and 5 cm H2O, respectively) in the spontaneous/timed mode that combines patient flow-triggering and backup time-triggering.

MEASUREMENTS AND MAIN RESULTS

After 30 mins, significant reductions in breathing frequency (32 +/- 4 to 26 +/- 5 breaths/min), heart rate (110 +/- 21 to 97 +/- 20 beats/min), blood pressure (mean 117 +/- 28 to 92 +/- 18 mm Hg), and Paco2 (56 +/- 15 to 43 +/- 9 torr [7.5 +/- 2 to 5.7 +/- 1.2 kPa]) were observed in the bilevel positive airway pressure group, as were significant improvements in arterial pH and dyspnea scores (p < .05 for all of these parameters). Only breathing frequency improved significantly in the CPAP group (32 +/- 4 to 28 +/- 5 breaths/min, p < .05). At 30 mins; the bilevel positive airway pressure group had greater reductions in Paco2 (p = .057), systolic blood pressure (p = .005), and mean arterial pressure (p = .03) than the CPAP group. The myocardial infarction rate was higher in the bilevel positive airway pressure group (71%) compared with both the CPAP group (31%) and historically matched controls (38%) (p = .05). Duration of ventilator use, intensive care unit and hospital stays, and intubation and mortality rates were similar between the two groups.

CONCLUSIONS

Bilevel positive airway pressure improves ventilation and vital signs more rapidly than CPAP in patients with acute pulmonary edema. The higher rate of myocardial infarctions associated with the use of bilevel positive airway pressure highlights the need for further studies to clarify its effects on hemodynamics and infarction rates, and to determine optimal pressure settings.

Noninvasive ventilation in acute cardiogenic pulmonary edema: systematic review and meta-analysis

CONTEXT

In patients with acute cardiogenic pulmonary edema noninvasive ventilation may reduce intubation rate, but the impact on mortality and the superiority of one technique over another have not been clearly established.

OBJECTIVE

To systematically review and quantitatively synthesize the short-term effect of noninvasive ventilation on major clinical outcomes.

DATA SOURCES

MEDLINE and EMBASE (from inception to October 2005) and Cochrane databases (library issue 4, 2005) were searched to identify relevant randomized controlled trials and systematic reviews published from January 1, 1988, to October 31, 2005.

STUDY SELECTION AND DATA EXTRACTION

Included trials were all parallel studies comparing noninvasive ventilation to conventional oxygen therapy in patients with acute pulmonary edema. Comparisons of different techniques, either continuous positive airway pressure (CPAP) or bilevel noninvasive pressure support ventilation (NIPSV), were also included.

DATA SYNTHESIS

Fifteen trials were selected. Overall, noninvasive ventilation significantly reduced the mortality rate by nearly 45% compared with conventional therapy (risk ratio [RR], 0.55; 95% confidence interval [CI], 0.40-0.78; P = .72 for heterogeneity). The results were significant for CPAP (RR, 0.53; 95% CI, 0.35-0.81; P = .44 for heterogeneity) but not for NIPSV (RR, 0.60; 95% CI, 0.34-1.05; P = .76 for heterogeneity), although there were fewer studies in the latter. Both modalities showed a significant decrease in the "need to intubate" rate compared with conventional therapy: CPAP (RR, 0.40; 95% CI, 0.27-0.58; P = .21 for heterogeneity), NIPSV (RR, 0.48; 95% CI, 0.30-0.76; P = .24 for heterogeneity), and together (RR, 0.43; 95% CI, 0.32-0.57; P = .20 for heterogeneity). There were no differences in intubation or mortality rates in the analysis of studies comparing the 2 techniques.

CONCLUSIONS

Noninvasive ventilation reduces the need for intubation and mortality in patients with acute cardiogenic pulmonary edema. Although the level of evidence is higher for CPAP, there are no significant differences in clinical outcomes when comparing CPAP vs NIPSV.

Association of noninvasive ventilation with nosocomial infections and survival in critically ill patients

CONTEXT

Invasive life-support techniques are a major risk factor for nosocomial infection. Noninvasive ventilation (NIV) can be used to avoid endotracheal intubation and may reduce morbidity among patients in intensive care units (ICUs).

OBJECTIVE

To determine whether the use of NIV is associated with decreased risk of nosocomial infections and improved survival in everyday clinical practice among patients with acute exacerbation of chronic obstructive pulmonary disease (COPD) or hypercapnic cardiogenic pulmonary edema (CPE).

DESIGN AND SETTING

Matched case-control study conducted in the medical ICU of a French university hospital from January 1996 through March 1998.

PATIENTS

Fifty patients with acute exacerbation of COPD or severe CPE who were treated with NIV for at least 2 hours and 50 patients treated with mechanical ventilation between 1993 and 1998 (controls), matched on diagnosis, Simplified Acute Physiology Score II, Logistic Organ Dysfunction score, age, and no contraindication to NIV.

MAIN OUTCOME MEASURES

Rates of nosocomial infections, antibiotic use, lengths of ventilatory support and of ICU stay, ICU mortality, compared between cases and controls.

RESULTS

Rates of nosocomial infections and of nosocomial pneumonia were significantly lower in patients who received NIV than those treated with mechanical ventilation (18% vs 60% and 8% vs 22%; P<.001 and P =.04, respectively). Similarly, the daily risk of acquiring an infection (19 vs 39 episodes per 1000 patient-days; P =.05), proportion of patients receiving antibiotics for nosocomial infection (8% vs 26%; P =.01), mean (SD) duration of ventilation (6 [6] vs 10 [12] days; P =.01), mean (SD) length of ICU stay (9 [7] vs 15 [14] days; P =.02), and crude mortality (4% vs 26%; P =.002) were all lower among patients who received NIV than those treated with mechanical ventilation.

CONCLUSIONS

Use of NIV instead of mechanical ventilation is associated with a lower risk of nosocomial infections, less antibiotic use, shorter length of ICU stay, and lower mortality. JAMA. 2000;284:2361-2367.

Improved survival in cancer patients requiring mechanical ventilatory support: Impact of noninvasive mechanical ventilatory support

OBJECTIVE

When a cancer patient becomes critically ill, mechanical ventilation (MV) is often considered futile. However, recent studies have found that outcomes of critically ill cancer patients have been improving over the years and that classic predictors of high mortality have lost their relevance.

DESIGN

We retrospectively determined outcomes and predictors of 30-day mortality in 237 mechanically-ventilated cancer patients admitted to the intensive care unit (ICU).

PATIENTS

The 132 (55.7%) patients who were admitted between 1990 and 1995 were compared with 105 (44.3%) patients who were admitted between 1996 and 1998. The malignancy was leukemia/lymphoma in 119 (50.3%) patients, myeloma in 50 (21%), and a solid tumor in 68 (28.7%). Forty-two (17.7%) patients had bone marrow transplantation, and 91 (38.4%) were neutropenic. Median Simplified Acute Physiology Score II (SAPS II) was 58 (range, 40-75). Reasons for MV were acute hypoxemic respiratory failure in 148 (62.5%) patients, coma in 54 (22.8%), and cardiogenic pulmonary edema in 35 (14.7%). Conventional MV was used first in 189 (79.8%) patients, and noninvasive MV (NIMV) was used in 48 (20.2%). Overall mortality rate was 72.5% (172 deaths).

RESULTS

Logistic regression identified three variables associated with mortality: ICU admission between 1996 and 1998 (odds ratio [OR], 0.24; 95% confidence interval [CI], 0.12-0.50) and the use of NIMV (OR, 0.34; 95% CI, 0.16-0.73) were protective, and the SAPS II was aggravating (OR, 1.04 per point; 95% CI, 1.02-1.06). To better define the impact of NIMV, we performed a pairwise-matched exposed-unexposed analysis. Forty-eight patients who did and 48 who did not receive NIMV as the first ventilation method were matched for SAPS II, type of malignancy, and period of ICU admission. Crude ICU mortality rates from exposed patients and controls were 43.7% and 70.8%, respectively. NIMV remained protective from mortality after adjustment for matching variables (OR, 0.31; 95% CI, 0.12-0.82).

CONCLUSION

Our results confirm that mortality has improved over the past decade in critically ill cancer patients, even those who require MV, and suggest that this may be, in part, because of a protective effect of NIMV.

Effect of non-invasive positive pressure ventilation (NIPPV) on mortality in patients with acute cardiogenic pulmonary oedema: a meta-analysis

BACKGROUND

Non-invasive positive pressure ventilation (NIPPV), using continuous positive airway pressure (CPAP) or bilevel ventilation, has been shown to reduce the need for invasive mechanical ventilation in patients with acute cardiogenic pulmonary oedema. We assessed additional benefits of NIPPV in a meta-analysis.

METHODS

Meta-analysis comparison in acute cardiogenic pulmonary oedema was undertaken to compare (1) CPAP with standard therapy (oxygen by face-mask, diuretics, nitrates, and other supportive care), (2) bilevel ventilation with standard therapy, and (3) bilevel ventilation with CPAP, incorporating randomised controlled trials identified by electronic and hand search (1966-May, 2005). In 23 trials that fulfilled inclusion criteria, we assessed the effect of NIPPV on hospital mortality and mechanical ventilation, estimated as relative risks.

FINDINGS

CPAP was associated with a significantly lower mortality rate than standard therapy (relative risk 0.59, 95% CI 0.38-0.90, p=0.015). A non-significant trend towards reduced mortality was seen in the comparison between bilevel ventilation and standard therapy (0.63, 0.37-1.10, p=0.11). We recorded no substantial difference in mortality risk between bilevel ventilation and CPAP (p=0.38). The need for mechanical ventilation was reduced with CPAP (0.44, 0.29-0.66, p=0.0003) and with bilevel ventilation (0.50, 0.27-0.90, p=0.02), compared with standard therapy; but no significant difference was seen between CPAP and bilevel ventilation (p=0.86). Weak evidence of an increase in the incidence of new myocardial infarction with bilevel ventilation versus CPAP was recorded (1.49, 0.92-2.42, p=0.11). Heterogeneity of treatment effects was not evident for mortality or mechanical ventilation across patients' groups.

INTERPRETATION

In patients with acute cardiogenic pulmonary oedema, CPAP and bilevel ventilation reduces the need for subsequent mechanical ventilation. Compared with standard therapy, CPAP reduces mortality; our results also suggest a trend towards reduced mortality after bilevel NIPPV.

Continuous positive airway pressure by face mask in acute cardiogenic pulmonary edema

The therapeutic efficacy of continuous positive airway pressure (CPAP) administered by face mask was studied in 40 patients with acute cardiogenic pulmonary edema and respiratory failure. Arterial blood gas values and pH, systemic arterial pressure, heart rate and respiratory rate were measured during administration of 30% oxygen with a high-flow face mask apparatus at ambient airway pressure. Twenty patients were then randomly chosen to continue ambient airway pressure breathing and 20 received 10 cm H2O of CPAP. The measurements were repeated 10, 60 and 180 minutes after therapy was initiated. During the first 10 minutes of CPAP treatment, arterial blood oxygen partial pressure increased 8 +/- 9 mm Hg (mean +/- 1 standard deviation), (p less than 0.01) and respiratory rate decreased 5 +/- 5 breaths/min (p less than 0.001). Systolic arterial pressure decreased 12 +/- 21 mm Hg (p less than 0.05), and heart rate by 10 +/- 11 beats/min (p less than 0.001). A decrease in respiratory rate by 2 +/- 5 breaths/min (p less than 0.05) was the only change that occurred in the control group. The improvement in arterial blood oxygenation persisted throughout the investigation period (p less than 0.05). Thirteen patients (65%) in the control group and 7 patients (35%) in the CPAP group met our criteria for treatment failure during the study (p = 0.068). Thus, CPAP administered by face mask improves gas exchange, decreases respiratory work, unloads circulatory stress, and may reduce the need for ventilator treatment in acute cardiogenic pulmonary edema.

Acute respiratory failure in the elderly: etiology, emergency diagnosis and prognosis

Introduction

Our objectives were to determine the causes of acute respiratory failure (ARF) in elderly patients and to assess the accuracy of the initial diagnosis by the emergency physician, and that of the prognosis.

Method

In this prospective observational study, patients were included if they were admitted to our emergency department, aged 65 years or more with dyspnea, and fulfilled at least one of the following criteria of ARF: respiratory rate at least 25 minute^-1; arterial partial pressure of oxygen (PaO₂) 70 mmHg or less, or peripheral oxygen saturation 92% or less in breathing room air; arterial partial pressure of CO₂ (PaCO₂) ≥ 45 mmHg, with pH ≤ 7.35. The final diagnoses were determined by an expert panel from the completed medical chart.

Results

A total of 514 patients (aged (mean ± standard deviation) 80 ± 9 years) were included. The main causes of ARF were cardiogenic pulmonary edema (43%), community-acquired pneumonia (35%), acute exacerbation of chronic respiratory disease (32%), pulmonary embolism (18%), and acute asthma (3%); 47% had more than two diagnoses. In-hospital mortality was 16%. A missed diagnosis in the emergency department was noted in 101 (20%) patients. The accuracy of the diagnosis of the emergency physician ranged from 0.76 for cardiogenic pulmonary edema to 0.96 for asthma. An inappropriate treatment occurred in 162 (32%) patients, and lead to a higher mortality (25% versus 11%; p < 0.001). In a multivariate analysis, inappropriate initial treatment (odds ratio 2.83, p < 0.002), hypercapnia > 45 mmHg (odds ratio 2.79, p < 0.004), clearance of creatinine < 50 ml minute^-1 (odds ratio 2.37, p < 0.013), elevated NT-pro-B-type natriuretic peptide or B-type natriuretic peptide (odds ratio 2.06, p < 0.046), and clinical signs of acute ventilatory failure (odds ratio 1.98, p < 0.047) were predictive of death.

Conclusion

Inappropriate initial treatment in the emergency room was associated with increased mortality in elderly patients with ARF.

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.

Lung overexpression of the vascular endothelial growth factor gene induces pulmonary edema

We hypothesized that the angiogenic mediator, vascular endothelial growth factor (VEGF), known to be expressed in the lung and to be capable of inducing local edema in skin, might evoke the development of lung edema if expressed in excess amounts. To test this hypothesis, we developed an in vivo model of VEGF overexpression in the lung on the basis of delivery to the respiratory epithelium of the VEGF165 complementary DNA by an E1(-) adenovirus vector (AdVEGF165). Administration of AdVEGF165 by the intratracheal route (10(9) plaque-forming units [pfu]) to C57Bl/6 mice showed increased expression of VEGF messenger RNA in lung tissue by Northern analysis. Overexpression of VEGF protein in the lung at Days 1 to 10 was confirmed by enzyme-linked immunosorbent assay. Intratracheal administration of AdVEGF165 resulted in a dose-dependent increase in lung wet/dry weight ratios over time, lung histology showed widespread intra- alveolar edema, and pulmonary capillary permeability was significantly increased as quantified by the Evans blue dye assay and [(131)I]albumin permeability. To confirm the specificity of these observations, mice were pretreated with intranasal administration of an adenovirus vector expressing a truncated soluble form of the VEGF receptor flt-1 (Adsflt). Adsflt (10(9) pfu) pretreatment completely abrogated the increased lung wet/dry weight ratio caused by AdVEGF165 administration, whereas an identical adenovirus vector with an irrelevant transgene had no effect upon subsequent AdVEGF165-induced pulmonary edema. Together, these data suggest that overexpression of VEGF in the lung may be one mechanism of increased pulmonary vascular permeability in the early stages of acute lung injury.

Relationship Between B-Type Natriuretic Peptides and Pulmonary Capillary Wedge Pressure in the Intensive Care Unit

OBJECTIVES

We examined whether B-type natriuretic peptides (BNP) can serve as noninvasive markers of pulmonary capillary wedge pressure (PCWP) in the setting of critical illness.

BACKGROUND

The BNP and N-terminal pro-B-type natriuretic peptide (NT-proBNP) are highly correlated with left ventricular (LV) filling pressures in patients with depressed LV systolic function. However, their relationship to PCWP in a heterogeneous intensive care unit (ICU) population has not been established.

METHODS

We prospectively studied 40 patients in the ICU requiring invasive hemodynamic monitoring. Hemodynamics were recorded simultaneously with blood sampling for BNP and NT-proBNP.

RESULTS

The BNP (median 420 pg/ml) and NT-proBNP (median 3,304 pg/ml) levels were markedly elevated, but weakly correlated with PCWP (BNP, r = 0.40, NT-proBNP, r = 0.32) and other cardiac parameters. Peptide levels were approximately four-fold greater in patients with impaired (estimated glomerular filtration rate [eGFR] <60 ml/min) versus normal (eGFR >60 ml/min) renal function, despite similar PCWP, cardiac index, and LV ejection fraction. In addition, both BNP and NT-proBNP showed stronger correlations with PCWP in patients with preserved (BNP, r = 0.58, NT-proBNP, r = 0.73) versus impaired renal function (BNP, r = 0.48, NT-proBNP, r = 0.34). Interaction terms between eGFR and BNP (p = 0.06) and NT-proBNP (p = 0.04) suggest that eGFR modulates the relationship of these peptides to filling pressures.

CONCLUSIONS

The BNPs are markedly elevated, yet show only weak correlations to PCWP in ICU patients requiring invasive hemodynamic monitoring. Thus, a single value for BNP or NT-proBNP may not be a clinically useful noninvasive marker of filling pressures in the critically ill patient. This appears to be especially true in patients with impaired renal function.

Reappraisal of continuous positive airway pressure therapy in acute cardiogenic pulmonary edema. Short-term results and long-term follow-up

To investigate whether serial incremental continuous positive airway pressure (CPAP) has any short-term or long-term advantages over face-mask oxygen therapy by way of intrapulmonary shunt reduction, 100 patients admitted to the coronary care unit for the treatment of acute cardiogenic pulmonary edema were studied. All patients received Swan-Ganz catheterization. Hemodynamic and pulmonary function parameters were recorded over the next 6 h, and the patients were followed until hospital discharge. All survivors received regular follow-up at 1-month intervals in the outpatient clinic. During the first-stage investigation period (3 h) PaO2 in the CPAP group showed a significant increase, whereas the intrapulmonary shunt and alveolar-arterial oxygen tension gradient (P[A-a]O2) was significantly reduced (p < 0.005). The CPAP group had significantly lower rate-pressure product and higher stroke volume index compared with the control group. The therapeutic failure rate over 6 h was 24% in the CPAP group and 50% in the control group (p < 0.01). The CPAP group had a significantly lower incidence of tracheal intubation and ventilator therapy than the control group; however, there was no significant difference in short-term mortality and hospital stay between the two groups. In conclusion, although study size was not large enough to demonstrate a difference in mortality, CPAP therapy resulted in physiologic cardiovascular and pulmonary function improvement and significantly reduced the need for intubation; however, it did not decrease mortality in patients with acute cardiogenic pulmonary edema, and a much larger study is needed to investigate this possibility.

Benefits and risks of success or failure of noninvasive ventilation

OBJECTIVE

Noninvasive ventilation (NIV) fails more frequently for de novo acute respiratory failure (de novo) than for cardiogenic pulmonary edema (CPE) or acute-on-chronic respiratory failure (AOC). The impact of NIV failure and success was compared between de novo and CPE or AOC after adjustment for disease severity.

SETTINGS

Patients requiring ventilatory support were enrolled in a prospective survey in 70 French ICUs. Of 1076 patients requiring ventilatory support, 524 were eligible, including 299 de novo (NIV use, 30%) and 225 CPE-AOC (NIV use, 55%).

DESIGN AND ANALYSIS

Independent risk factors associated with mortality and length of stay were identified by logistic regression analysis. The adjusted outcome of NIV success or failure was compared to that with endotracheal intubation without NIV.

RESULTS

NIV success was independently associated with survival in both de novo, adjusted OR 0.05 (95% CI 0.01-0.42), and CPE-AOC OR 0.03 (CI 0.01-0.24). NIV failure was associated with ICU mortality in the de novo group (OR 3.24, CI 1.61-6.53) but not in the CPE-AOC group. Nosocomial pneumonia was less common in patients successful with NIV. NIV failure was associated with a longer ICU stay in CPE-AOC only. The overall use of NIV was independently associated with a better outcome only in CPE-AOC patients (OR 0.33, CI 0.15-0.73).

CONCLUSION

The effect of NIV differs between de novo and CPE-AOC patients because NIV failure is associated with increased mortality for de novo patients. This finding should raise a note of caution when applying NIV in this indication.

Increased use of noninvasive ventilation in French intensive care units

OBJECTIVES

A prospective survey of French intensive care units (ICUs) in 1997 showed moderate and variable use of noninvasive ventilation (NIV). This study examined changes in NIV use in French ICUs after the intervening 5years.

SETTINGS

Patients were enrolled in a prospective survey in 70 French ICUs.

METHODS

Three-week survey, with prospective inclusion of all patients requiring ventilatory support.

MEASUREMENTS AND RESULTS

Overall 1,076 patients received ventilatory support (55% of admissions). First-line NIV was significantly more common than 5years earlier, overall (23% vs. 16%) and especially in patients not intubated before ICU admission (52% vs. 35%). Reasons for respiratory failure were coma (33%), cardiogenic pulmonary edema (8%), acute-on-chronic respiratory failure (17%), and de novo respiratory failure (41%). Significant increases in NIV use were noted for acute-on-chronic respiratory failure (64% vs. 50%) and de novo respiratory failure (22% vs. 14%). Among patients given NIV, 38% subsequently required endotracheal intubation (not significantly different). Independent risk factors for NIV failure were high SAPS II and de novo respiratory failure, whereas factors associated with success were good NIV tolerance and high body mass index.

CONCLUSIONS

NIV use has significantly increased in French ICUs during the past 5years, and the success rate has remained unchanged. In patients not previously intubated, NIV is the leading first-line ventilation modality. The proportion of patients successfully treated with NIV increased significantly over the 5-year period (13% vs. 9% of all patients receiving ventilatory support).