Effect of afterload reduction on plasma volume during acute heart failure

Decrease of haemoconcentration reliably detects hydrostatic pulmonary oedema in dyspnoeic patients in the emergency department - a machine learning approach

BACKGROUND

Haemoglobin variation (ΔHb) induced by fluid transfer through the intestitium has been proposed as a useful tool for detecting hydrostatic pulmonary oedema (HPO). However, its use in the emergency department (ED) setting still needs to be determined.

METHODS

In this observational retrospective monocentric study, ED patients admitted for acute dyspnoea were enrolled. Hb values were recorded both at ED presentation (T0) and after 4 to 8 h (T1). ΔHb between T1 and T0 (ΔHbT1-T0) was calculated as absolute and relative value. Two investigators, unaware of Hb values, defined the cause of dyspnoea as HPO and non-HPO. ΔHbT1-T0 ability to detect HPO was evaluated. A machine learning approach was used to develop a predictive tool for HPO, by considering the ability of ΔHb as covariate, together with baseline patient characteristics.

RESULTS

Seven-hundred-and-six dyspnoeic patients (203 HPO and 503 non-HPO) were enrolled over 19 months. Hb levels were significantly different between HPO and non-HPO patients both at T0 and T1 (p < 0.001). ΔHbT1-T0 were more pronounced in HPO than non-HPO patients, both as relative (-8.2 [-11.2 to -5.6] vs. 0.6 [-2.1 to 3.3] %) and absolute (-1.0 [-1.4 to -0.8] vs. 0.1 [-0.3 to 0.4] g/dL) values (p < 0.001). A relative ΔHbT1-T0 of -5% detected HPO with an area under the receiver operating characteristic curve (AUROC) of 0.901 [0.896-0.906]. Among the considered models, Gradient Boosting Machine showed excellent predictive ability in identifying HPO patients and was used to create a web-based application. ΔHbT1-T0 was confirmed as the most important covariate for HPO prediction.

CONCLUSIONS

ΔHbT1-T0 in patients admitted for acute dyspnoea reliably identifies HPO in the ED setting. The machine learning predictive tool may represent a performing and clinically handy tool for confirming HPO.

Repeated assessment of physical biomeasures or blood biomarkers for the definition of volume status and cardiac loading in LVSD

The application of biomarker technology can be usefully implemented in areas where current techniques are inadequate and where a clinical issue, which affects outcome, can be defined. The definition of the loading status of the heart where there is pre-existent impairment of contractile function is a key target. Heart failure is a complex clinical presentation with many varied etiologies, but at the essence of its successful management is the reliable definition of cardiac volume loading. Traditional and many current technological measures are applied to define this relationship, yet their accuracy and performance in individual patients is either basically inadequate or poorly understood and applied. There is a wide range of both physical measurements and blood biomarkers that can be considered to better define this key issue in patients with ventricular systolic impairment. Their performance is considered in detail in this review.

Factors associated with pulmonary edema in severe scorpion sting patients--a multivariate analysis of 428 cases

OBJECTIVE

To determine clinical and routine laboratory factors associated with pulmonary edema secondary to scorpion envenomation.

DESIGN AND SETTING

Retrospective study covering 13 years (1990-2002) in the medical Intensive Care Unit of a university hospital (Sfax-Tunisia).

PATIENTS

428 patients older than 3 years who were admitted to the intensive care unit for scorpion envenomation were included in this study. Patients were stratified into two groups according to the presence or absence of pulmonary edema as assessed by a medical committee.

MEASUREMENTS AND RESULTS

The mean (+/- SD) age was 17.5 +/- 17.7 years, ranging from 3 to 76 years. The pulmonary edema group included 294 patients (68.7%). A multivariate analysis found the following factors to be correlated with a pulmonary edema: age less than 5 years (p = 0.04), sweating (p = 0.004), agitation (p = 0.01), leukocytes of 25000 cells/mm3 or more (p = 0.02), and a plasma protein concentration of 72 g/L or more (p < 0.0001). In addition, a plasma protein concentration of 72 g/L or more predicted the presence of pulmonary edema with a sensitivity of 78% a specificity of 88%, a positive predictive value of 93%, and negative predictive value of 64%. Almost 84% of patients having a respiratory rate of > or = 30 breaths/minute associated with agitation and sweating were classified in the pulmonary edema group. This clinical association indicates the presence of pulmonary edema with a specificity of 84.3% and a positive predictive value of 87.5%.

CONCLUSION

In scorpion envenomation patients older than 3 years, the association of a respiratory rate of > or = 30 breaths/minute, agitation, sweating, or the presence of high plasma protein concentrations suggest the presence of pulmonary edema.

Modern Management of Cardiogenic Pulmonary Edema

Cardiogenic pulmonary edema (CPE) is a life-threatening condition that is frequently encountered in standard emergency medicine practice. Traditionally, diagnosis was based on physical assessment and chest radiography and treatment focused on the use of morphine sulfate and diuretics. Numerous advances in diagnosis and treatment have been made, however. Serum testing for B-type natriuretic peptide (BNP) has improved the accuracy of diagnoses in these patients. Treatment should focus on fluid redistribution with aggressive preload and afterload reduction rather than simply on diuresis. Some specific medications and noninvasive positive pressure ventilation have been shown to be safe and rapidly effective in improving patients' symptoms and improve outcomes.

Relation of unrecognized hypervolemia in chronic heart failure to clinical status, hemodynamics, and patient outcomes

Clinically unrecognized intravascular volume overload may contribute to worsening symptoms and disease progression in patients with chronic heart failure (CHF). The present study was undertaken to prospectively compare measured blood volume status (determined by radiolabeled albumin technique) with clinical and hemodynamic characteristics and patient outcomes in 43 nonedematous ambulatory patients with CHF. Blood volume analysis demonstrated that 2 subjects (5%) were hypovolemic (mean deviation from normal values -20 +/- 6%), 13 subjects (30%) were normovolemic (mean deviation from normal values -1 +/- 1%), and 28 subjects (65%) were hypervolemic (mean deviation from normal values +30 +/- 3%). Physical findings of congestion were infrequent and not associated with blood volume status. Increased blood volume was associated with increased pulmonary capillary wedge pressure (p = 0.01) and greatly increased risk of death or urgent cardiac transplantation during a median follow-up of 719 days (1-year event rate 39% vs 0%, p <0.01 by log-rank test). Systolic blood pressure was significantly lower in hypervolemic patients than in those with normovolemia or hypovolemia (107 +/- 2 vs 119 +/- 2 mm Hg, p = 0.008), and hypotension was independently associated with increased risk of hypervolemia in multivariate analysis (odds ratio 2.64 for a 10-mm Hg decrease in systolic blood pressure, 95% confidence interval 1.13 to 6.19, p = 0.025). These findings demonstrate that clinically unrecognized hypervolemia is frequently present in nonedematous patients with CHF and is associated with increased cardiac filling pressures and worse patient outcomes.

Ketanserin, a serotonin antagonist. Administration in patients with acute respiratory failure

Increased release of serotonin (5-hydroxytryptamine, 5-HT) can play a significant role in the development of acute respiratory failure. The hemodynamic effects of ketanserin, a selective inhibitor of 5-HT2 receptors, were studied in eight patients who developed acute respiratory insufficiency after an episode of circulatory shock. Administration of ketanserin was associated with reductions in systemic and pulmonary artery pressures, without significant change in heart rate or cardiac output. Concomitant decreases in hemoglobin and protein concentrations suggested an associated increase in plasma volume. These changes were attributed to an increased peripheral pooling of blood related to vasodilation. Arterial oxygenation and pulmonary shunt were unaffected. These results indicate ketanserin represents a promising vasoactive agent for treatment of acute respiratory failure in critically ill patients.

Place of vasoactive agents in the treatment of acute circulatory failure

Increase in total cardiac output can improve oxygen delivery to the cells. Although inotropic drugs increase primarily myocardial contractility, they can adversely affect cardiac preload and afterload. Moreover, they can dangerously increase myocardial oxygen requirements. The combined use of vasodilating agents, with fluid challenge represents a challenging but more efficient treatment of acute circulatory failure.

Contribution of the risk factor concept to patient care in coronary heart disease

This article deals with the question of whether or not the risk factor concept, a principal aspect of preventive cardiology, has contributed to patient care in coronary heart disease. The risk factors considered are plasma cholesterol, high blood pressure, smoking, diabetes and marked obesity. With the exception of plasma cholesterol and diabetes, all of these factors enhance myocardial oxygen consumption and thus, in the presence of coronary insufficiency, promote myocardial ischemia. Their modification is therefore good general medical practice, even if not related to coronary atherosclerosis. Diabetes needs adequate medical treatment in patients both with and without coronary atherosclerosis. Because of the occasional occurrence of spontaneous regression of coronary atherosclerosis and the morphologic and functional complexity of coronary artery pathology, it has never been and probably never will be demonstrated that lowering plasma cholesterol levels by diet or other means will cause regression of coronary atherosclerosis. It follows that modification or treatment of risk factors is implemented for good medical reasons but does not demonstrably or predictably affect coronary artery disease. It is concluded that the contribution of the risk factor concept to patient care in coronary heart disease has been, and still is, trivial.

The effects of terbutaline on acid base, serum electrolytes, and glucose homeostasis during the management of preterm labor

Terbutaline (T) is a beta-adrenergic compound which is commonly employed as a tocolytic agent in preterm labor. We evaluated the metabolic and biophysical consequences of infusion of T into six pregnant women in preterm labor. Our results showed that the infusion of T led to the development of hyperglycemia, hyperinsulinemia, hyperlactacidemia, hypokalemia, a fall in serum colloid osmotic pressure and pH, a rise in maternal heart rate, and a fall in maternal blood pressure. These changes in electrolytes in the serum occurred in the absence of any significant alterations in their urinary excretion. These data suggest that the infusion of T causes hyperglycemia that results in a rise in serum insulin and lactate, which, in turn, leads to a fall in serum potassium, ionized calcium, and pH. Volume expansion as manifested by a fall in colloid osmotic pressure may contribute to the reduction in the levels of ionized and total calcium. Thus, careful monitoring of electrolytes and hydration status is warranted when beta-mimetic agents are used, specifically T, for tocolytic therapy.

Use of methylprednisolone in patients following acute myocardial infarction. Hemodynamic and metabolic effects

Hemodynamic and metabolic effects of methylprednisolone were investigated in a double-blind study of 28 patients with acute myocardial infarction (AMI), confirmed by unequivocal electrocardiographic and enzyme changes. Measurements were performed prior to and at 1.5, 3, 4, 4.5, 12 and 24 hours following infusion of methylprednisolone (13 patients) or placebo (15 patients). Although systemic vascular resistance decreased from 1,750 to 1,420 dynes . sec . cm-5 (p less than .001) and cardiac index increased from 2.77 to 3.10 L/min/m2 (p less than .02) between 0 and 4.5 hours, an abnormal increase in blood lactate was observed in 10 of the 13 patients following administration of methylprednisolone (3.0 vs 1.2 mM/L, p less than .001). Lactate elevation appeared one hour after infusion of methylprednisolone, was maximal at 12 hours, and persisted for more than 24 hours. There was no significant change in blood lactate in placebo treated patients. A transient but significant decrease in plasma volume was also observed following infusions of methylprednisolone. The elevation of blood lactate could not be explained by the reduction in plasma volume since the most striking increases in lactate were observed 12 hours following the initial infusion of methylprednisolone when the plasma volume was returning to the control value. No significant differences in other hemodynamic or metabolic parameters, infarct size or patient survival were observed between the two groups. We conclude that the hemodynamic benefits of glucocorticoids characterized by increased cardiac output and lowered systemic vascular resistance are counterbalanced by the potentially unfavorable conditions of lactate elevation and volume depletion.

Effects of methylprednisolone on P50, 2,3 diphosphoglycerate and arteriovenous oxygen difference in acute myocardial infarction

In a double-blind randomized study, 30 mg/kg of methylprednisolone sodium succinate (MPN) or 15 mg/kg of mannitol placebo (PL) were infused in 28 patients after acute myocardial infarction. Measurements were obtained immediately before and after for 24 hours after the initial infusion. The partial pressure of oxygen at 50% saturation of hemoglobin (P50) did not change significantly in vitro or in vivo after MPN, whereas 2,3 diphosphoglycerate (2,3 DPG) increased from 13.2 to 14.2 mumol/g Hb (p < 0.05) in the group receiving PL. The arteriovenous oxygen difference (Ca-VO2) remained constant after MPN or PL. The cardiac index (CI) increased after MPN (p < 0.02) associated with an increase in the oxygen consumption index (CI X A-V O2) from 146 to 170 ml/min/m2 (p < 0.05). These data show that MPN increases CI after acute myocardial infarction, but has no specific effects on P50, 2,3 DPG or Ca-VO2.