Dopamine in the treatment of hypotension and shock

Impact of Medical Interventions and Comorbidities on Norwood Admission for Patients with Hypoplastic Left Heart Syndrome

The purpose of these analyses was to determine how specific comorbidities and medical interventions impact risk of inpatient mortality in those with hypoplastic left heart syndrome undergoing Norwood procedure. The secondary aims were to determine the impact of these on billed charges, postoperative length of stay, and risk of cardiac arrest. Admissions from 2004 to 2015 in the Pediatric Health Information System database with hypoplastic left heart syndrome and Norwood procedure were identified. Admission characteristics, patient interventions, and the presence of comorbidities were captured. A total of 5,138 admissions were identified meeting inclusion criteria. Of these 829 (16.1%) experienced inpatient mortality, and 352 (6.7%) experienced cardiac arrest. The frequency of inpatient mortality did not significantly change over the course of the study era. The frequency of cardiac arrest significantly decreased from 7.4% in 2004 to 4.3% in 2015 (p = 0.04). The frequency of pharmacologic therapies, particularly vasoactive use, decreased as the study period progressed. Regression analyses demonstrated a significant association between cardiac arrest and inpatient mortality with arrhythmias, acute kidney injury, and pulmonary hypertension. Similarly, regression analyses demonstrated a significant association between increase in billed charges and length of stay with year of surgery, presence of heart failure, syndromes, and acute kidney injury. For patients with hypoplastic left heart syndrome undergoing the Norwood procedure, the frequency of pharmacologic therapies and cardiac arrest has decreased over time. There are significant associations between acute kidney injury, arrythmias, and pulmonary hypertension with cardiac arrest and mortality.

Vasoactive Agent Use in Septic Shock: Beyond First-Line Recommendations

Septic shock is a life-threatening disorder associated with high mortality rates requiring rapid identification and intervention. Vasoactive agents are often required to maintain goal hemodynamics and preserve tissue perfusion. However, guidance regarding the proper administration of adjunct agents for the management of septic shock is limited in patients who are refractory to norepinephrine. This review summarizes vasopressor agents and describes the nuanced application of these agents in patients with septic shock, specifically focusing on clinical scenarios with limited guidance including patients who are nonresponsive to first-line agents and individuals with mixed shock states, tachyarrhythmias, obesity, valvular abnormalities, or other comorbid conditions.

Diagnosis and Management of Acute Congestive Heart Failure in the Intensive Care Unit

Congestive heart failure has emerged as an important public health problem in the United States and is pres ently the number one Diagnostic Related Group for inpatients over the age of 65. Patients admitted to an intensive care or coronary care unit because of de compensated heart failure are frequently older and frequently have multiple serious medical problems. In addition to standard intensive care practices, it is often important to characterize systolic and diastolic proper ties qualitatively with echocardiography. Hemodynamic monitoring is essential for patients with hypotension, oliguria, or questionable left ventricular filling pressures. A combination of loop diuretics, intravenous vaso dilators, and inotropic agents will often be necessary to correct severe underlying hemodynamic abnormalities, and an understanding of basic left ventricular systolic and diastolic function is essential to the optimal use of these potent agents. Manipulation of loading conditions and contractile state are important considerations, and pharmacological interventions should be targeted to ward specific abnormalities in individual patients. Once patients are stabilized, switching to orally active inotro pic and vasodilator agents can usually be accomplished over a 24-hour period, allowing for a total stay of 48 to 72 hours in the intensive care unit.

Congestive heart failure (CHF) is rapidly becoming a public health problem of major proportions [1- 5]. As the American population continues to age, we can expect greater numbers of patients to be admitted to intensive care units (ICUs) and coro nary care units (CCUs) with progressive decompen sation of previously stable CHF. Our current ap proaches to the diagnosis and management of acute heart failure are summarized; however, the care of such patients must always be highly individualized.

β(3)-Adrenoceptor Antagonist SR59230A Attenuates the Imbalance of Systemic and Myocardial Oxygen Transport Induced by Dopamine in Newborn Lambs

Background

In neonates, the increase in O₂-delivery (DO₂) by dopamine is offset by a greater increase in O₂-consumption (VO₂). This has been attributed to β₃-adrenergic receptors in neonatal brown fat tissue. β₃ receptors in the heart have negative inotropic properties. We evaluated the effects of SR59230A, a β₃-antagonist, on the balance of systemic and myocardial O₂-transport in newborn lambs treated with dopamine.

Methods

Lambs (2–5 days old, n = 12) were anesthetized and mechanically ventilated. Heart rate (HR) and rectal temperature were monitored. VO₂ was measured by respiratory mass spectrometry and cardiac output (CO) by a pulmonary artery transonic flowmeter. Arterial, jugular bulb venous and coronary sinus blood gases and lactate were measured to calculate DO₂, O₂ extraction ratio (ERO₂), myocardial O₂ and lactate extraction ratios (mERO₂, mERlac). After baseline measurements, lambs were randomized to receive SR59230A at 5 mg/kg iv (SRG) or placebo. Both groups received incremental doses of a dopamine infusion (0–5–10–15–20 mcg/kg/min) every 15 min. Measurements were repeated at the end of each dose.

Results

After SR59230A infusion, CO and HR trended to decrease (P = 0.06), but no significant changes occurred in other parameters. Over the incremental doses of dopamine, temperature increased in both groups (P < 0.0001) but to a lesser degree in SRG (P = 0.004). CO and HR increased (P = 0.005 and 0.04) and similarly in both groups (P > 0.1). DO₂ trended to a small increase (P = 0.08). VO₂ increased in both groups (P < 0.0001) but to a lesser degree in SRG (P < 0.0001). As a result, ERO₂ increased in both groups (P < 0.0001), but to a lesser degree in SRG (P < 0.0001). mERO₂ was lower in SRG (P = 0.01) with a faster increase (P < 0.0001). mERlac was higher in SRG (P = 0.06) with a faster decrease (P = 0.04).

Conclusion

Although SR59230A tends to induce an initial drop in CO, it significantly attenuates the rise in VO₂ and hence the imbalance of systemic and myocardial O₂ transport induced by dopamine at higher doses. Studies are warranted to examine the effect of SR59230A in cases of cardiac dysfunction and increased VO₂, observed after cardiac surgery.

Historical perspectives in critical care medicine: blood transfusion, intravenous fluids, inotropes/vasopressors, and antibiotics

Significant progress in critical care medicine has been the result of tireless observation, dedicated research, and well-timed serendipity. This article provides a historical perspective for four meaningful therapies in critical care medicine: blood transfusion, fluid resuscitation, vasopressor/inotropic support, and antibiotics. For each therapy, key discoveries and events that have shaped medical history and helped define current practice are discussed. Prominent medical and social pressures that have catalyzed research and innovation in each domain are also addressed, as well as current and future challenges.

Adverse Effects of Dopamine on Systemic Hemodynamic Status and Oxygen Transport in Neonates After the Norwood Procedure

OBJECTIVES

The purpose of this study was to evaluate the effects of dopamine on hemodynamic status and oxygen transport in neonates after the Norwood procedure.

BACKGROUND

Dopamine is widely used to augment cardiac performance and increase oxygen delivery (DO2) in patients after cardiopulmonary bypass (CPB). This might be at the expense of increased myocardial and systemic oxygen consumption (VO2), thus offsetting the improved DO2. This balance is particularly fragile in critically ill neonates.

METHODS

Systemic oxygen consumption was continuously measured with respiratory mass spectrometry in 13 sedated, paralyzed, and mechanically ventilated neonates for 72 h after the Norwood procedure. Arterial, superior vena caval, and pulmonary venous blood gases were measured to calculate pulmonary blood flow (Q(p)) and systemic blood flow (Q(s)), DO2, and oxygen extraction ratio (ERO2). Rate-pressure product was calculated. Dopamine at a dose of 5 microg/kg/min was routinely administered at cessation of CPB and terminated within the first 48 h. Hemodynamic and oxygen transport measures were obtained before and at 100 min after the termination of dopamine.

RESULTS

Terminating dopamine was not associated with significant changes in arterial pressure, Q(p), Q(s), or DO2 but was associated with a significant decrease in heart rate (p = 0.003), rate-pressure product (p = 0.03), and VO2 (-20 +/- 11%, p < 0.0001), resulting in a significant decrease in ERO2 (p = 0.01).

CONCLUSIONS

Dopamine induces a significant increase in VO2 in neonates after the Norwood procedure, and termination is associated with an improved balance of VO2-DO2. These data further emphasize the importance of understanding changes in VO2 as well as DO2 in infants after cardiac surgery.

The Last 100 Years of Sepsis

Over the last 100 years, huge advances have been made in the field of sepsis in terms of pathophysiology, epidemiology, diagnosis, monitoring, and therapeutics. Here, we offer our perspective of the key changes and current situation in each of these areas. Despite these changes, mortality rates remain unacceptably high and continued progress, particularly in early diagnosis and therapy, is urgently needed.

Current usage of dopamine in New Zealand intensive care units

A nation-wide evaluation of dopamine usage in New Zealand Intensive Care Units (ICUs) was undertaken. Twenty-six public hospital ICUs participated. Twenty-two ICUs (85%) use dopamine as an inotrope. Seventeen ICUs use dopamine for presumed selective renal effects at least occasionally, but with wide variation in what is considered to be "renal-dose". Level 3 ICUs were less likely to use "renal-dose" dopamine than levels 1 and 2 (P= 0.01). Nineteen units (83%) use weight-referenced (i.e., microg x kg(-1) x min(-1)) dopamine administration. Weight-referenced administration and "renal-dose" dopamine were likely to be in use together (P=0.02). Standard dopamine dilutions varied widely with a median of 2 mg x ml(-1) (range 0.4 to 8 mg x ml(-1)). Given a demonstrated association between weight-referenced administration and "renal-dose" dopamine, along with particular pharmacokinetic and pharmacodynamic reservations, the value of weight-referenced administration of dopamine in adult patients is questioned.

Endocrine predictors of acute hemodynamic effects of growth hormone in congestive heart failure

BACKGROUND

The aim of our study was to assess whether there could be any clinical and/or endocrine (spontaneous growth hormone [GH] secretion rate, baseline insulin-like growth factor-1 [IGF-1]) predictors and/or determinants of the acute effects of continuous intravenous infusion of recombinant human GH on hemodynamic parameters in 12 patients with dilated cardiomyopathy and congestive heart failure (CHF).

METHODS AND RESULTS

The study involved 12 male patients with chronic CHF (ischemic in 8 patients and idiopathic in 4). Ten patients were in New York Heart Association functional class III or IV and 2 in class II. The first 24 hours were considered the control period; in fact, during the following 24 hours, all the patients underwent intravenous constant pump infusion of recombinant human GH. Blood samples for GH assay were taken every 20 minutes during the first night of the study (from 10 PM to 6 AM). Moreover, blood samples for GH assay were also taken during exogenous GH infusion. Blood samples for IGF-1 assays were taken at 8 AM of each of the 3 days of the study. Pulmonary artery pressure (PAP) and capillary wedge (PCWP) pressure, cardiac index, and arterial blood pressure were measured 30 minutes after right heart catheterization (baseline 1), at the end of the control period (baseline 2), and every 4 hours during GH infusion. A negative correlation has been found between mean nocturnal GH levels and baseline IGF-1 levels (r = -0.47, P =.124) and between mean nocturnal GH levels and both postinfusion absolute (r = -0.67, P <.05) and delta (postinfusion-preinfusion) (r = -0.58; P < 005) IGF-1 levels. No significant correlations have been found between several parameters of liver function (albumin, bilirubin, and pseudocholinesterase) and mean nocturnal GH. However, baseline IGF-1 levels showed a negative significant correlation (r = -0.76, P <.01) with total bilirubin and a positive correlation (r = 0.72, P <.01) with pseudocholinesterase. Baseline IGF-1 levels showed a significant negative correlation with baseline mean PAP (r = -0.68, P <.05) and PCWP (r = -0.70, P <.05) and a positive correlation with baseline cardiac index (r = 0.71, P <.05). Baseline IGF-1 levels also showed a significant negative correlation with absolute mean PAP (r = -0.63, P <.05) and mean PCWP (r = -0.67, P <.05) after GH infusion. After GH infusion, IGF-1 levels also negatively correlated with post-GH infusion mean PAP (r = -0.50, P =.09) and mean PCWP (r = -0.66, P <.05). The positive correlation between either baseline or postinfusion IGF-1 and the postinfusion cardiac index (r = 0.40 and 0.43, respectively) did not reach statistical significance.

CONCLUSIONS

GH has acute functional effects on the heart in patients with CHF, including both an increase in myocardial contractility and a decrease in vascular resistances, and among patients with CHF, those with low baseline IGF-1 are likely to have fewer beneficial effects from GH infusion.

Parenteral inotropic support for advanced congestive heart failure

Parenterally administered positive inotropic agents remain an important component of the therapeutics of cardiac dysfunction and failure. Dobutamine, a catechol, remains the prototype of this drug group, but recently has been joined by the phosphodiesterase III inhibitor, milrinone. Compared with dobutamine, milrinone has greater vasodilating-unloading properties. The catecholamine, dopamine, is often used as a parenteral positive inotrope; but at moderate to high dose, it evokes considerable systemic vasoconstriction. At lower doses, dopamine appears to augment renal function. Levosimendan and toborinone, new compounds with several mechanisms of action, are under active clinical investigation and review for approval. Parenteral positive inotropic therapy is indicated for short-term (hours to days) treatment of cardiovascular decompensation secondary to ventricular systolic dysfunction, low-output heart failure. More prolonged or continuous infusion of one of these agents may be necessary as a "pharmacologic bridge" to cardiac transplantation, another definitive intervention, or more advanced, intense medical therapy. An occasional patient will require a continuous infusion via indwelling venous catheter and portable pump, simply to be able to be discharged from the hospital setting and function in the home environment. Intermittent parenteral inotropic therapy for chronic heart failure has provoked considerable controversy and passion among cardiologists and heart failure specialists; an attempt is made to present this topic in an objective manner.

Relationships between dopamine infusions and intracranial hemodynamics in patients with raised intracranial pressure

Dopamine, 1-10 micrograms/kg body weight/min was infused in 6 patients suffering from cerebrovascular diseases with elevated intracranial pressure and a critical cerebral perfusion pressure. Dopamine decreased intracranial pressure in 3 and increased it moderately in the other 3 patients. In all patients, the dopamine-induced rise of mean arterial pressure led to an increase of cerebral perfusion pressure. Transcranial Doppler ultrasonographic recordings of the middle cerebral artery in patients whose intracranial pressure declined revealed a decrease of the pathologically elevated cerebrovascular resistance, and an augmentation of cerebral blood supply. In conclusion, dopamine infusions may improve cerebral hemodynamics in some patients with severe brain edema. Such patients can be identified by intracranial pressure and Doppler monitoring.

Acute haemodynamic effects of ibopamine and dopamine on isovolumic relaxation

The effects of intraduodenal ibopamine (a new orally active inotropic agent claimed to have haemodynamic effects similar to dopamine) on isovolumic relaxation were monitored for 90 min in eight closed-chest anaesthetized dogs. Dopamine and epinine (ibopamine active metabolite) were also infused at graded doses. After 15 min, ibopamine (12 mg/kg) shortened the time constant of isovolumic relaxation, and increased stroke volume and mean aortic pressure. Peak positive dP/dt increased significantly only 10 min later. Heart rate did not change. Dopamine (10 micrograms/kg per min) similarly reduced the time constant, and increased stroke volume, mean aortic pressure, peak positive dP/dt and heart rate. Epinine (10 micrograms/kg per min) caused similar changes in peak positive dP/dt, stroke volume, mean aortic pressure, and accelerated time constant without raising the heart rate. Ibopamine and epinine therefore significantly improved the isovolumic relaxation phase, like dopamine, without however affecting the heart rate.

[Indications for inotropic agents in cardiac surgery]

Inotropic drugs are widely used before, during and after cardiac surgery. Besides the old well known inotropic drugs, new sympathomimetic drugs and phosphodiesterase inhibitors are available. They can be used alone or in combination. The choice of drug is difficult to make and depends, for one part, on the side-effects of each drug. Before surgery, they are required for patients who present with cardiogenic shock while waiting for emergency repair of their lesion. During surgery, inotropic drugs are used before, during and after using cardiopulmonary bypass. After surgery, they are used to treat low cardiac output states. A decision algorithm is suggested, but it is modified by personal clinical experience, aetiological patterns and pharmacological data. Therapeutic doses must be adjusted according to haemodynamic data. Physiological controls are required, such as venous return and heart rate. Mechanical assistance devices must not be forgotten, especially after myocardial reperfusion and weaning from extracorporeal circulation.

Combined hemodynamic effects of dopamine and dobutamine in cardiogenic shock

In eight mechanically ventilated patients in cardiogenic shock, we assessed the hemodynamic effects of an infusion of dopamine and dobutamine and evaluated its role in preventing the deleterious effects of administering each amine alone. Each patient received three infusions in a randomly assigned order: dopamine, 15 micrograms/kg/min; dobutamine, 15 micrograms/kg/min; and a combination of dopamine, 7.5 micrograms/kg/min, and dobutamine, 7.5 micrograms/kg/min. Stroke volume index increased similarly with the three infusions, but dopamine alone increased oxygen consumption (p less than 0.05 vs dobutamine alone and dopamine-dobutamine combined). The dopamine-dobutamine combination increased mean arterial pressure (p less than 0.05 vs dobutamine), maintained pulmonary capillary wedge pressure within normal limits (p less than vs dopamine), and prevented the worsening of hypoxemia induced by dopamine (p less than 0.05). The dopamine-dobutamine combination appears to be useful in the management of mechanically ventilated patients in cardiogenic shock.

Adrenal medullary secretion of dopamine in response to hemorrhagic and endotoxin-induced shock in dogs

Adrenal medullary secretion of dopamine (DA) was investigated during acute hemorrhagic and endotoxin-induced shock in mongrel dogs. Blood samples were collected directly from the adrenal vein and DA content was measured using gas-liquid chromatography equipped with an electron-capture detector (GLC-ECD). The adrenal medullary secretion of DA increased markedly during hemorrhagic and endotoxin-induced shock. In the former, the rate of secretion of DA increased from 0.22 ng/kg/min to 10.7 ng/kg/min in 90 min. After blood transfusion, the rate of secretion of DA decreased rapidly. In the case of endotoxin-induced shock, the rate of secretion of DA increased from 0.20 ng/kg/min to 9.6 ng/kg/min in 120 min. In the cervical spinal transected dogs, the rate of secretion of DA did not increase during hemorrhagic shock. Thus, secretion of DA from the adrenal medulla seems to be primarily controlled by the central nervous system, through the baroreceptor reflex.

Cardiovascular dopamine receptors: physiological, pharmacological and therapeutic implications

Dopamine receptor activation can lead to pronounced changes in cardiovascular function. The myriad of effects produced by dopamine receptor agonists results from the activation of dopamine receptors located at different anatomical sites in the cardiovascular system. Further basic research is required to better characterize these dopamine receptors so as to allow the development of more specific dopamine receptor agonists. Endogenous dopamine may be involved in the physiological control of fluid and electrolyte balance and continuing research efforts in this area should provide for a better understanding of the role of cardiovascular dopamine receptors in the maintenance of overall circulatory homeostasis. Cardiovascular dopamine receptor stimulation represents an important and promising approach for the development of novel therapeutic agents for the treatment of hypertension, angina pectoris, congestive heart failure and acute renal failure.

Dopamine infusion in man. Plasma catecholamine levels and pharmacokinetics

Dopamine is widely used in the treatment of hypotensive conditions and/or impending renal failure, but the plasma levels of dopamine and other catecholamines in association with dopamine infusion are not known. Plasma catecholamines and dopamine pharmacokinetics during and after dopamine infusion were therefore studied in man. Two and 5 micrograms x kg-1 x min-1 of dopamine were infused for 30 min in two groups of five patients. Dose-dependent mean steady state levels with fairly large interindividual variations were reached within 5 min. Elimination of dopamine from plasma after termination of infusion had a biphasic course with t 1/2 alpha around 1 min and t 1/2 beta about 9 min in both groups. Noradrenaline plasma levels and blood pressure increased significantly in the 5 micrograms group. It is suggested that the vasoconstriction with deleterious effects on tissue perfusion, seen in conjunction with high-dose dopamine infusion, may be due to increased noradrenaline levels.

Comparison of haemodynamic responses to dopamine and salbutamol in severe cardiogenic shock complicating acute myocardial infarction

Twelve patients with severe persistent cardiogenic shock complicating acute myocardial infarction underwent single crossover treatment with intravenous dopamine and salbutamol to determine the more beneficial therapy. Salbutamol (10 to 40 microgram/min) reduced systemic vascular resistance and progressively increased both cardiac index and stroke index. Heart rate increased from 95 to 104 beats/min. Changes in mean arterial pressure and pulmonary artery end-diastolic pressure were small and insignificant. Dopamine infusion at rates of 200 and 400 micrograms/min also increased cardiac index and stroke index. Systemic vascular resistance fell slightly but mean arterial pressure rose from 57 to 65 mm Hg. Heart rate increased from 95 to 105 beats/min. Changes in pulmonary artery end-diastolic pressure were again small and insignificant. Dopamine infusion at 800 micrograms/min caused an appreciable increase in systemic vascular resistance; a further increment in mean arterial pressure was observed, though cardiac index fell slightly. Heart rate and pulmonary artery end-diastolic pressure rose steeply. Salbutamol, a vasodilator, increased cardiac output in patients with cardiogenic shock complicating acute myocardial infarction but did not influence blood pressure. If correction of hypotension is essential dopamine in low doses may be the preferred agent. Doses of 800 microgram/min, which is within the therapeutic range, worsen other manifestations of left ventricular dysfunction.

Beneficial effects of prolonged low dose dopamine in hospitalized patients with severe refractory heart failure

In 10 hospitalized patients with severe congestive heart failure refractory to standard medical therapy for three days, low dose intravenous dopamine (2-4 micrograms/kg/min) was infused for 48 h. Heart rate and systolic blood pressure were unchanged throughout the study. Mean pulmonary artery wedge pressure decreased significantly during the dopamine infusion from 27 +/- 6 (SD) to 18 +/- 6 mmHg (p less than 0.01) and cardiac output increased from 3.2 +/- 1.1 to 4.6 +/- 0.8 l/min (p less than 0.001). A diuresis was initiated in all patients and there was a significant weight loss during the study which averaged 5 lbs (p less than 0.01). All patients improved symptomatically from class IV (NYHA) to class III and were more responsive to conventional therapy after the study. No adverse reactions were noted in this dose range. We conclude that low dose intravenous dopamine is efficacious in improving hemodynamics and initiating a diuresis in patients with severe refractory congestive heart failure.

Comparative systemic and regional hemodynamic effects of dopamine and dobutamine in patients with cardiomyopathic heart failure

Thirteen patients with severe cardiac failure underwent a single crossover study of dopamine and dobutamine in order to compare the systemic and regional hemodynamic effects of the two drugs. The dose-response data demonstrated that dobutamine (2.5--10 microgram/kg/min) progressively and predictably increases cardiac output by increasing stroke volume, while simultaneously decreasing systemic and pulmonary vascular resistance and pulmonary capillary wedge pressure. There was no change in heart rate or premature ventricular contractions (PVCs)/min at this dose range. Dopamine (2--8 microgram/kg/min) increased the stroke volume and cardiac output at 4 microgram/kg/min. Dopamine at less than 4 microgram/kg/min provided little additional increase in cardiac output and increased the pulmonary wedge pressure and the number of PVCs/min. At greater than 6 microgram/kg/min, dopamine increased heart rate. During the 24-hour maintenance-dose infusion of each drug (dopamine 3.7--4, dobutamine 7.3--7.7 microgram/kg/min), only dobutamine maintained a significant increase of stroke volume, cardiac output, urine flow, urine sodium concentration, creatinine clearance and peripheral blood flow. Renal and hepatic blood flow were not signfiicantly altered by the maintenance dose of either drug. Systemic and regional hemodynamic data suggest that dobutamine has many advantages over dopamine when infused in patients with cardiac failure.

Combined nitroprusside-dopamine therapy in severe chronic congestive heart failure. Dose-related hemodynamic advantages over single drug infusions

To assess the circulatory effects of afterload reduction and inotropism individually and in combination as rational therapy for refractory heart failure, nitroprusside and dopamine were administered to 13 patients with severe cardiac decompensation. Dopamine at average doses of 3 and 7 microgram/kg per min produced increases in cardiac output and reductions in peripheral resistance. At doses of 15 microgram/kg per min, dopamine increased heart rate, peripheral arterial pressure and side effects. Nitroprusside alone decreased left-sided filling pressures and increased cardiac output. When the agents were administered together, the increases in cardiac output were significantly greater than with either agent alone and there was physiologic improvement in overall circulatory function. The relations among changes in afterload (systemic impedence), preload (filling pressures) and cardiac index help to explain the salutary effects of combined therapy in patients with refractory heart failure.

Hospital treatment of congestive heart failure. Management according to hemodynamic profile

Selection of therapy for subjects with acute congestive dardiac failure usually involves a choice among a diuretic, a vasodilator and an inotropic agent. Three principal questions are involved in the decision: (1) Is cardiac out normal or depressed? (2) Is blood pressure normal or depressed? (3) is regional myocardial ischemia present? Diuretics are safe and easy to administer, but they do not increase cardiac output or relieve hypoperfusion. Inotropic agents increase cardiac output but differ widely in their effects on blood pressure: selection of specific agents is influenced by their blood pressure effect. All inotropic agents, however, potentially aggravate regional myocardial ischemia. In ischemic heart failure, therefore, vasodilators which also increase cardiac output, may be chosen. Vasodilator administration is in turn limited by the decrease in arterial pressure which accompanies increasing infusion rate. When these three questions are considered in combination, an effective therapeutic regimen can be identified. Thus, congestion without hypoperfusion requires a diuretic if blood pressure is normal; and a vasodilator when blood pressure is increased. In the presence of congestion with hypoperfusion, a vasodilator is employed if blood pressure is normal; and a positive inotropic drug when blood pressure is depressed.

Selection of vasodilator, inotropic or combined therapy for the management of heart failure

Vasodilator and inotropic drugs work through independent mechanisms in augmenting left ventricular pump function in patients with heart failure. The selection between these two classes of pharmacologic agents for an individual patient may be based on the control blood pressure as well as the underlying disease. Although vasodilator drugs are easiest and safest to employ in patients with normal or high arterial presure levels, even in relatively hypotensive subjects (systolic arterial pressure less than 105 mm Hg), a salutary hemodynamic effect can be achieved without an undue decrease in pressure. Inotropic drugs may be safest to administer to patients without coronary artery disease, but the oxygen-consuming effect of these drugs need not necessarily have an adverse effect on patients with ischemic heart disease. Combined vasodilator and inotropic drug therapy is the most potent pharmacologic means of restoring pump function in patients with severe heart failure. The long-term use of vasodilator and inotropic drugs in the treatment of heart failure is dependent on the availability of agents that will produce a sustained hemodynamic effect. Hydralazine, nitrates and prazosin have been employed alone or in combination and provide a promising approach to vasodilator treatment of heart failure. Better and more selective oral inotropic agents are needed to allow this therapeutic modality to be employed optimally.

The use of dopamine in children

Dopamine was used as the primary catecholamine to treat circulatory shock, manifested by either systemic arterial hypotension or oliguria or both, in 24 children two days to 18 years (mean = 39 months) of age. The dose of dopamine ranged from 0.3 to 25 (mean = 9.3) microgram/kg/minute. The primary problem in four of the 24 patients was infection; two of these patients survived. The other 20 patients had congenital heart disease; 18 developed shock following surgery. Even of these 20 patients survived. With dopamine infusion the average systolic blood pressure increased from 69 +/- 4 (mean +/- SEM) to 81 +/- 4 mm Hg (P less than 0.001) and the mean urine output increased from 0.8 +/- 0.2 to 2.7 +/- 0.8 ml/kg/hour (P less than 0.05). Dopamine produced no adverse consequences. Thirteen patients responded favorably to the drug, with a significant increase in systemic arterial blood pressure and urine production. Four patients did not respond to dopamine and seven had an equivocal response. None of the four patients in whom dopamine was ineffective survived. Although only nine of the 20 patients who responded favorably or equivocally survived, conventional therapy had failed to alter the unfavoarble course in any of the patients.

Effect of dopamine on hemodynamics and myocardial metabolism in shock following acute myocardial infarction in man

Eight patients in shock associated with acute myocardial infarctions were treated with dopamine. We titrated the dopamine dose to increase mean arterial pressure to 65-70 mm Hg and urine output to greater than 40 ml/hr. Increase of heart rate to 120-125 beats/min and occurrence of potentially dangerous arrhythmias were limiting end-points. Dopamine administration averaged 17.2 microgram/kg/min. Heart rate increased from 95 to 118 beats/min (P less than 0.001), and mean arterial pressure rose from 60 to 65 mm Hg (P less than 0.05). Dopamine increased myocardial contractility as indicated by increase in cardiac index and systolic ejection rate, with only moderate decrease in systemic vascular resistance. Pulmonary wedge pressure and right atrial pressure decreased from 23 to 18 mm Hg (P less than 0.05) and from 10 to 8 mm Hg (P less than 0.001) respectively. Improvement in hemodynamic status by dopamine was associated with deterioration of myocardial metabolism. Myocardial oxygen extraction ratios and arterial-coronary sinus oxygen differences increased from 73 to 76% (P less than 0.05) and from 13.02 to 14.19 ml/100 ml (P less than 0.02) respectively. Myocardial lactate production increased from -8 to -15% (P = 0.05). We conclude that dopamine improved cardiac performance at the expense of myocardial oxygenation and that dopamine is potentially harmful to acutely ischemic myocardium.

Haemodynamic effects of dopamine, epinephrine and orciprenaline (Alupent) in patients early after cardiac surgery

The haemodynamic effects of Dopamine (100, 250 and 500 mcg/min), Epinephrine (4 and 8 mcg/min), Orciprenaline (4 and 8 mcg/min) and two combinations of Dopamine 250 mcg/min with Epinephrine and Orciprenaline 4 mcg/min respectively at constant infusion rates were studied in 21 patients after cardiac surgery. Special attention was payed to four types of catecholamine infusions during which the highest cardiac index (CI), 161-168% of control, was seen: Dopamine 500 mcg/min (D 500), Epinephrine 8 mcg/min (E 8), Dopamine 250 mcg/min combined with Epinephrine 4 mcg/min (D 250 + E4) and Dopamine 250 mcg/min combined with Orciprenaline 4 mcg/min (D 250 + Or 4). At the same time mean arterial pressure (MAP) was highest with D 500 (137%) and lowest during both combined infusions (120 and 125%). Total peripheral resistance (TPR) was lowest during the combined infusions (80 and 81% of control) and highest during D 500 (89%). The relative increase of stroke index (SVI) and heart rate (HR) in favor of SVI, given as a quotient SVI/HR, was highest with D 250 + E4(3.7), followed by E 8 (1.9), D 500 (1.6) and D 250 + Or 4 (1.3). It was concluded that a combined infusion of Dopamine and Epinephrine, both in low doses, is preferable to a high dose of Dopamine, or Epinephrine alone, producing the same increase of cardiac output with less afterload and less chronotropic effect than high doses of either drug alone.

Avoidance of vascular complications associated with the use of dopamine

Dopamine, dihydroxyphenylethylamine has three distinct actions depending on dosage. Low doses in the range of 1-2 mcg/kg/min result in vasodilatation. Medium doses of 2-10 mcg/kg/min increase cardiac output due to beta adrenergic action, while above 10 mcg/kg/min a potent vasoconstrictor effect predominates. Because of this last action great care must be used to avoid extravasation of infusions of dopamine directly into the tissue. Dopamine is a very useful agent but carries great potential to do local damage. Administration through a catheter placed into a large vein is recommended. Should extravasation occur, prompt infiltration of the area with phentolamine and a local anaesthetic, local cooling and regional sympathetic block may reduce the damage. The case is reported of a patient who suffered extensive necrosis in the forearm following local extravasation of dopamine.

Haemodynamic effects of dopamine in septic shock

The Haemodynamic response to dopamine infusion has been assessed in 30 patients in septic shock with myocardial dysfunction. Dopamine infusion resulted in a haemodynamic improvement as indicated by significant increases in cardiac output of 38.4% (p less than .001), stroke volume 18.7% (p less than .001), and mean arterial pressure of 33% (p less than .001). Despite the inotropic effect, left ventricular filling pressure did not change in 20 cases and increased in 10 cases. Mean peripheral resistance remained unchanged with a scatter of individual responses depending upon factors such as dopamine dose and initial vascular resistance. Dopamine increased intrapulmonary shunting by 48% (p less than .001), insignificantly decreased PaO2, increased mixed venous oxygen saturation by 16% (p less than .02) and decreased pulmonary vascular resistance by 15% (p less than .02). Both isoprenaline and dopamine improve stroke volume by an inotropic action, with an increase in venous return in the case of the latter and a reduction in afterload in the former. It is concluded that the usefulness of dopamine in septic shock may be limited in patients with previous myocardial disease because of the risk of increasing preload and in hypoxaemic patients because of the risk of increasing intrapulmonary shunting.

A comparative study on the influence of dopamine and metaproterenol on the ventricular fibrillation threshold in cats

The influence of 3-4-dihydroxyphenylethylamine (dopamine) on the VFT of the cat heart was checked with different doses in comparison to metaproterenol (Alupent). In the therapeutical doses dopamine has no significant influence on the VFT in contrast to metaproterenol. The clinical relevance of our findings seems to be that dopamine can be applied in therapeutical doses without running the risk of inducing serious cardiac arrhythmia.

Pharmacology of the renal circulation

The circulatory response of the kidney to drugs is conditioned by a variety of factors, such as basal vascular tone, dietary sodium and structural changes in the renal vasculature which accompany aging and disease. In addition, any drug which affects systemic arterial pressure will activate renal autoregulatory processes, which are superimposed upon the direct effects of the drug on the renal circulation. Renal autoregulation in addition to passive pressure effects probably accounts for the relative constancy of renal blood flow during the administration of renal vasodilators such as nitroprusside, diazoxide and minoxidil. Renal vasodilators which have minor effects on systemic arterial pressure, such as dopamine and glucagon, increase renal blood flow. These effects have been employed clinically in low cardiac output states. A variety of drugs affect the renal circulation by modifying the effects of endogenous vasoactive substances. The mechanisms of action include: receptor blockade; ex, adrenergic and Ag II-mediated vasoconstriction: enhanced production by the administration of biochemical precursors; ex, arachidonic acid and I-dopa: inhibition of endogenous production; ex, prostaglandin synthetase inhibitors: and inhibition of breakdown of endogenous substances; ex, converting enzyme inhibition. The effect of each of these interventions will depend in part upon the rate of endogenous production of the relevant vasoactive material. The administration of diuretics affects renal blood flow in individually distinctive ways, the mechanisms of which have been only partially elucidated.

The hemodynamic effects of dopamine following cardiopulmonary bypass

The hemodynamic effects of dopamine were studied in 19 patients following intracardiac operation or myocardial revascularization using extracorporeal circulation. The heart rate, mean blood pressure, central venous pressure, left atrial and pulmonary artery pressures, cardiac output, and urine output were recorded before and at the end of one-hour infusions of dopamine at 5, 10, and 15 mug/kg/min. Infusion of 5 mug/kg/min of dopamine resulted in the highest gain in cardiac output and stroke work without an increase in myocardial oxygen consumption, as evidenced by lack of significant rise in heart rate. In addition, this dosage was not accompanied by an increase in pulmonary or systemic vascular resistance, nor were other untoward effects observed after administration of 5 mug/kg/min of dopamine.

Haemodynamic effects of dobutamine in patients with coronary artery disease

The haemodynamic effects of the infusion of dobutamine in dosages of 2-5, 5-0 and 10-0 mug/kg/min were studied in twelve patients with coronary artery disease. At the lowest dose, infusion of dobutamine caused a significant increase in cardiac output; greater increases occurred with doses of 5-0 and 10-0 mug/kg/min. The means by which the myocardium produced the increase in cardiac output differed according to the dose of the drug; 2-5 and 5-0 mug/kg/min produced an increase in stroke volume without any significant variation in the heart rate. At the highest dose rate, an increase in heart rate made a distinct contribution to the overall increase in output. The ventricular dp/dt max. increased at all three dosages. Blood pressure, pulmonary arterial and capillary pressure, and left ventricular and diastolic pressure did not show any significant change. The separation of the inotropic and the chronotropic effects of dobutamine according to the infused dose appears to have extremely interesting clinical implications.