Acute cardiogenic pulmonary edema: clinical and noninvasive evaluation

Striking volume intolerance is induced by mimicking arterial baroreflex failure in normal left ventricular function

BACKGROUND

Patients with heart failure and preserved ejection fraction (HFpEF) are supersensitive to volume overload, and a striking increase in left atrial pressure (LAP) often occurs transiently and is rapidly resolved by intravascular volume reduction. The arterial baroreflex is a powerful regulator of intravascular stressed blood volume. We examined whether arterial baroreflex failure (FAIL) mimicked by constant carotid sinus pressure (CSP) causes a striking increase in LAP and systemic arterial pressure (AP) by volume loading in rats with normal left ventricular (LV) function.

METHODS AND RESULTS

In anesthetized Sprague-Dawley rats, we isolated bilateral carotid sinuses and controlled CSP by a servo-controlled piston pump. We mimicked the normal arterial baroreflex by matching CSP to instantaneous AP and FAIL by maintaining CSP at a constant value regardless of AP. We infused dextran stepwise (infused volume [Vi]) until LAP reached 15 mm Hg and obtained the LAP-Vi relationship. We estimated the critical Vi as the Vi at which LAP reached 20 mm Hg. In FAIL, critical Vi decreased markedly from 19.4 ± 1.6 mL/kg to 15.6 ± 1.6 mL/kg (P < .01), whereas AP at the critical Vi increased (194 ± 6 mm Hg vs 163 ± 6 mm Hg; P < .01). We demonstrated that an artificial arterial baroreflex system we recently developed could fully restore the physiologic volume intolerance in the absence of native arterial baroreflex.

CONCLUSIONS

Arterial baroreflex failure induces striking volume intolerance in the absence of LV dysfunction and may play an important role in the pathogenesis of acute heart failure, especially in states of HFpEF.

The epidemiological enigma of heart failure with preserved systolic function

BACKGROUND

Current epidemiological evidence suggests that the prevalence of preserved systolic function in patients with heart failure varies widely from 13 to 74%. This inconsistency suggests a lack of consensus as to what this condition really is and how it has been characterised for epidemiological studies.

AIMS

In this review, we summarise and discuss the current understanding of the epidemiology of heart failure with preserved systolic function and the challenges that this raises.

METHODS

Studies were identified from Medline and Embase Literature Database searches using the subject headings heart failure, diastolic heart failure, epidemiology, incidence, prevalence, diagnosis, prognosis and mortality.

RESULTS

Sixty-one studies of congestive heart failure with preserved systolic function were reviewed. There is great diversity in the criteria used to determine whether heart failure is present, the patient population, the setting of the study and methods of evaluating left ventricular function. This makes epidemiological studies of prevalence, morbidity and mortality impossible to compare.

CONCLUSIONS

The diagnosis of this syndrome might be better defined in terms of symptoms, elevated neuro hormones and impaired cardiac workload. This would allow accurate identification of cases so that further research could be conducted to measure outcome and assess therapeutic benefit.

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.

Utility of history, physical examination, electrocardiogram, and chest radiograph for differentiating normal from decreased systolic function in patients with heart failure

To determine whether clinical parameters alone can differentiate normal versus decreased systolic left ventricular function in patients with heart failure. Detailed clinical data were collected prospectively from 225 consecutive patients who were hospitalized with heart failure. Findings in patients with normal (ejection fraction > or =45%) or decreased (ejection fraction <45%) left ventricular function were compared. Systolic function was normal in 104 patients (46%) and decreased in 121 patients (54%). Patients with normal function were older (mean [+/- SD] age, 59 +/- 13 years vs. 54 +/- 13 years, P = 0.007) and more likely to be female (56% vs. 35%, P = 0.001), obese (body mass index > or =30 kg/m(2), 62% vs. 48%, P = 0.04), have marked systolic (> or =160 mm Hg, 50% vs. 27%, P <0.001) and diastolic (> or =110 mm Hg, 25% vs. 13%, P = 0.02) hypertension, and use calcium antagonists (34% vs. 14%, P = 0.001). Patients with decreased function were more likely to use alcohol (37% vs. 20%, P = 0.007), angiotensin-converting enzyme (ACE) inhibitors (85% vs. 62%, P <0.001), and digoxin (57% vs. 27%, P <0.001); and more likely to have tachycardia (51% vs. 32%, P = 0.004), rales (89% vs. 80%, P = 0.05), electrocardiographic left ventricular hypertrophy (42% vs. 22%, P = 0.002), left atrial abnormality (52% vs. 22%, P <0.001), or flow cephalization on chest radiograph (91% vs. 79%, P = 0.02). Only sex, tachycardia, and use of digoxin and ACE inhibitors were associated with ventricular function in multivariable analysis. However, the sensitivity, specificity, and predictive values for all clinical variables were low. Differences in clinical parameters in heart failure patients with decreased versus normal systolic function cannot predict systolic function in these patients, supporting recommendations that heart failure patients should undergo specialized testing to measure ventricular function.

How well can the chest radiograph diagnose left ventricular dysfunction?

OBJECTIVES

To review the diagnostic utility of the chest radiograph for left ventricular dysfunction.

DATA SOURCES

Structured MEDLINE searches, citation reviews of relevant primary research, review articles, and textbooks, personal files, and data from experts.

STUDY SELECTION

Studies of patients without valvular disease that allowed calculation of the sensitivity and specificity of selected radiographic signs compared with a criterion standard of increased left ventricular preload or reduced ejection fraction.

DATA EXTRACTION

Two independent readers reviewed 29 studies. Studies were pooled after stratification by radiographic finding, criterion standard, and clinical setting.

MAIN RESULTS

Redistribution best diagnosed increased preload with a sensitivity of 65% (95% confidence interval [CI] 55%, 75%) and specificity 67% (95% CI 53%, 79%). Cardiomegaly best diagnosed decreased ejection fraction with a sensitivity of of 51% (95% CI 43%, 60%) and specificity of 79% (95% CI 71%, 85%). Interrater reliability was fair to moderate for redistribution and moderate for cardiomegaly. The clinical setting affected results by decreasing the specificity of cardiomegaly to 8% in detecting increased preload in patients with severe systolic dysfunction. The absence of redistribution could only exclude increased preload in situations in which the suspicion (pretest probability) of disease was less than 9%, whereas redistribution could confirm increased preload when the pretest probability was greater than 91%. The absence of cardiomegaly could only exclude a reduced ejection fraction if the pretest probability was less than 8%, whereas cardiomegaly could confirm a reduced ejection fraction if the pretest probability was greater than 87%.

CONCLUSIONS

Redistribution and cardiomegaly are the best chest radiographic findings for diagnosing increased preload and reduced ejection fraction, respectively. Unfortunately, neither finding alone can adequately exclude or confirm left ventricular dysfunction in usual clinical settings. Redistribution is not always reliably interpreted.

Prevalence, clinical features and prognosis of diastolic heart failure: an epidemiologic perspective

Numerous reports suggest that about one-third of patients with congestive heart failure do not have any abnormality of left ventricular systolic function. These patients presumably have heart failure on the basis of ventricular diastolic dysfunction. Our objective was to develop a comprehensive overview of published reports of the prevalence, clinical features and prognosis of diastolic heart failure and to offer recommendations for future studies. Thirty-one studies of patients with congestive heart failure with normal left ventricular systolic function were published in the time period from January 1970 through March 1995. These studies were identified with the use of computer-based searches in relevant data bases. Among patients with congestive heart failure, the prevalence of normal ventricular systolic performance in the published reports varies widely from 13% to 74%; the reported annual mortality rate also varies from 1.3% to 17.5%. The criteria for congestive heart failure, its chronicity and the age of the study sample affect the reported prevalence and prognosis of the disorder. The clinical signs and symptoms of diastolic heart failure are similar to those of patients with systolic heart failure, underscoring the need for evaluation of ventricular systolic function in patients with congestive heart failure. In the absence of any large-scale randomized clinical trial targeting these patients, the optimal treatment of diastolic heart failure is unclear. We conclude that the heterogeneity in previous studies of diastolic heart failure hinders the comparison of published reports. There is a need to conduct prospective, community-based investigations to better characterize the incidence, prevalence and natural history of diastolic heart failure. Randomized clinical trials are needed to determine optimal treatment strategies.

Pulmonary edema in pregnancy

Normal cardiovascular and respiratory changes in pregnancy can predispose women to the development of pulmonary edema. Conditions and treatments unique to pregnancy, such as multiple gestation or tocolysis, further increase this risk. Recognition of risk factors and signs and symptoms of pulmonary edema allows the nurse to intervene quickly, thus decreasing potential complications to the mother and child.

Initial treatment of pulmonary edema: a physiological approach

An understanding of the physiological principles involved in lung fluid balance is useful in the initial treatment of pulmonary edema. Normally, a very small volume of fluid is filtered from the pulmonary vasculature into the interstitial space. This interstitial fluid enters the pulmonary lymphatics and is transferred to mediastinal lymphatics at an estimated rate of 20 ml/hr. Under abnormal circumstances, fluid filtration may occur at such a rapid rate that it overwhelms the lymphatics and interstitial space and results in alveolar flooding. This may occur as a result of increased pulmonary vascular pressure or increased vascular permeability. The two general goals of initial therapy are (1) to relieve hypoxemia and (2) to reduce pulmonary capillary pressure. Relieving hypoxemia may require the use of supplemental oxygen by nasal prongs or mask, continuous positive airway pressure (CPAP) mask, or even endotracheal intubation and mechanical ventilation. Measures to decrease preload and thereby reduce pulmonary capillary pressure include sitting the patient up, administering a loop diuretic or morphine intravenously, and in some circumstances using sublingual nitroglycerin. After initial treatment is underway, a search for and specific management of the underlying cause of pulmonary edema can proceed.

Reliability of three computer methods in the analysis of ECG-gated radionuclide left ventriculography: interrecording, interobserver and intraobserver variability

Three different computer methods for analysis of systolic and diastolic left ventricular function (ejection fraction, peak ejection rate, time to peak ejection rate, peak filling rate, time to peak filling rate, duration of fast filling phase, and fast filling fraction) as derived from ECG-gated radionuclide cardiography were compared in 30 patients with various diseases. The patients had two gamma camera recordings of the left ventricle performed immediately following one another during radionuclide (99mTc) equilibrium (3 x 10(6) counts, 16 frames/cycle, 64 x 64 pixels). Mean ECG R-R interval of the patients remained unchanged from first to second recording. The three computer methods were: (1) end-diastolic (ED) region of interest (ROI) analysis based on manually defined ED-ROI; (2) multi (M) ROI, manually defined ROI for each frame; and (3) semiautomatic (SA) ROI, ROI for each frame defined by an SA edge detection technique. With the 16 frame points as nodes, a 160-point time-activity curve was constructed for each of the three methods by use of a spline function. A tailored multiway analysis of variance showed that the M-ROI method had the highest interindividual range of values of the function parameters and the smallest interrecording, interobserver, and intraobserver variabilities. In theory this implies a better diagnostic sensitivity and specificity for the M-ROI method as compared with the other two methods.

Bedside diagnosis of preserved versus impaired left ventricular systolic function in heart failure

The importance of recognizing symptomatic heart failure with preserved left ventricular (LV) systolic function has only recently been appreciated. To determine its frequency and identify clinical features that make the bedside diagnosis likely, 82 patients admitted for decompensated heart failure were classified into 2 groups based on their LV systolic performance, as defined by fractional shortening (FS): group I (n = 59), with impaired systolic function (fractional shortening less than 24%), and group II (n = 23) with preserved systolic function (fractional shortening greater than or equal to 24%). Mean fractional shortening was 15 +/- 5% and 39 +/- 1% for groups I and II, respectively. Female gender (p less than 0.05), obesity (p less than 0.01) and diastolic blood pressure greater than or equal to 105 mm Hg (p less than 0.05) predominated in group II. Jugular venous distention was identified more frequently in group I (p less than 0.05). No statistically significant difference between the 2 groups was noted among various demographic variables (age, duration of symptoms, history of hypertension, ischemic heart disease and heavy alcohol drinking) or physical findings (S3 gallop, edema, cardiomegaly, pulmonary congestion and pulmonary edema). Echocardiographic mean left ventricular dimension measured 6.6 +/- 1 versus 5.0 +/- 1 cm (p less than 0.01) and mean posterior wall thickness 1.1 +/- 0.3 versus 1.4 +/- 0.4 cm (p less than 0.01) in group I and II, respectively. The combination of diastolic blood pressure greater than or equal to 105 mm Hg and an absence of jugular venous distention had a high specificity and positive predictive value (100%) for identifying group II patients.(ABSTRACT TRUNCATED AT 250 WORDS)