Pericardial Tamponade ===================== Diagnosis --------- Ewart's sign: "1. undue prominence of the sternal end of the first rib in certain cases of pericardial tamponade. 2. Bronchial breathing and dullness on percussion at the lower angle of the left scapula in pericardial effusion." Pins' sign: "Ewart's sign, definition 2." Beck's Triad (1937): low BP, high venous pressure, quiet heart Pulsus Paradoxus Electrical Alternans on EKG Water Bottle Heart on CXR RV diastolic collapse on echo equalization of pressures on right heart cath --------------------------------------------------------------------------- The use of fluid loading and inotropic support are listed in most textbooks as temporizing measures (until pericrdiocentesis and surgery can be performed). Experimental studies in animals (via VETLINE) indicate the potential usefulness of isoproterenol and dobutamine (1,2,3,4,5). Only (3) has some human subjects and it suggests a limited role for inotropic support prior to definitive treatment. H. Louzon MD (1) Cohen MV Myocardial blood flow during cardiac tamponade in dogs with coronary occlusion: effects of isoproterenol. Am Heart J 1985 May;109(5 Pt 1):1032-8 To determine the effects of cardiac tamponade in dogs with ligation of the left anterior descending coronary artery, fluid was introduced into the pericardial space to raise right and left atrial and pericardial pressures, first to 7 to 9 mm Hg and then to 11 to 12 mm Hg. Normal and ischemic myocardial blood flow fell approximately 20% to 25% during mild tamponade (1.27 +/- 0.16 to 1.00 +/- 0.06 ml/min/gm and 0.52 +/- 0.12 to 0.39 +/- 0.08 ml/min/gm, respectively) and by 50% during moderate tamponade (0.66 +/- 0.08 and 0.23 +/- 0.05 ml/min/gm, respectively). The inner/outer left ventricular wall blood flow ratio decreased modestly from 1.16 to 1.08 (p less than 0.025) in normal areas but increased from 0.53 to 0.61 (p less than 0.05) in the ischemic regions, suggesting possible epicardial vessel compression. Isoproterenol resulted in prompt decreases in pericardial and filling pressures, 16% increase in aortic pressure, and 200% rise in cardiac output. Normal myocardial blood flow more than doubled (1.55 +/- 0.12 ml/min/gm, p less than 0.001). Although average ischemic blood flow rose slightly to 0.042 +/- 0.10 ml/min/gm, the increase was not significant. Furthermore, changes in ischemic blood flow were heterogeneous with frank decrease in one dog. Therefore, although isoproterenol has salutary hemodynamic effects, its unpredictable action on myocardial blood flow should cause one to use it cautiously in those with tamponade who are believed to have coronary occlusive disease. (2) Millard RW, Fowler NO, Gabel M Hemodynamic and regional blood flow distribution responses to dextran, hydralazine, isoproterenol and amrinone during experimental cardiac tamponade. J Am Coll Cardiol 1983 Jun;1(6):1461-70 Four different interventions were examined in dogs with cardiac tamponade. Infusion of 216 to 288 ml saline solution into the pericardium reduced cardiac output from 3.5 +/- 0.3 to 1.7 +/- 0.2 liters/min as systemic vascular resistance increased from 4,110 +/- 281 to 6,370 +/- 424 dynes . s . cm-5. Left ventricular epicardial and endocardial blood flows were 178 +/- 13 and 220 +/- 12 ml/min per 100 g, respectively, and decreased to 72 +/- 14 and 78 +/- 11 ml/min per 100 g with tamponade. Reductions of 25 to 65% occurred in visceral and brain blood flows and in a composite brain sample. Cardiac output during tamponade was significantly increased by isoproterenol, 0.5 microgram/kg per min intravenously; hydralazine, 40 mg intravenously; dextran infusion or combined hydralazine and dextran, but not by amrinone. Total systemic vascular resistance was reduced by all interventions. Left ventricular epicardial flow was increased by isoproterenol, hydralazine and the hydralazine-dextran combination. Endocardial flow was increased by amrinone and the combination of hydralazine and dextran. Right ventricular myocardial blood flow increased with all interventions except dextran. Kidney cortical and composite brain blood flows were increased by both dextran alone and by the hydralazine-dextran combinations. Blood flow to small intestine was increased by all interventions as was that to large intestine by all except amrinone and hydralazine. Liver blood flow response was variable. The most pronounced hemodynamic and tissue perfusion improvements during cardiac tamponade were effected by combined vasodilation-blood volume expansion with a hydralazine-dextran combination. Isoproterenol had as dramatic an effect but it was short-lived. Amrinone was the least effective intervention. (3) Martins JB, Manuel WJ, Marcus ML, Kerber RE Comparative effects of catecholamines in cardiac tamponade: experimental and clinical studies. Am J Cardiol 1980 Jul;46(1):59-66 In experimental cardiac tamponade, catecholamines improve hemodynamic variables. To determine whether hemodynamic changes result in increased blood flow to critical organs, tamponade was produced in nine spontaneously breathing, anesthetized dogs. Infusion of dopamine, isoproterenol or norepinephrine doubled cardiac output, but only norepinephrine increased mean arterial pressure. All catecholamines increased blood flow to the myocardium, but not to the brain or kidney. Isoproterenol caused a significant decrease in the endocardial/epicardial blood flow ratio, which was shown to be due to tachycardia. To determine whether catecholamines increase cardiac output and mean arterial pressure in patients with tamponade, eight patients with tamponade due to neoplasms were studied before therapeutic pericardiocentesis. Cardiac output increased only 50 percent with dopamine and isoproterenol and not at all with norepinephrine. Cardiac filling pressure did not decrease with isoproterenol or dopamine, as in experimental tamponade. Only norepinephrine increased mean arterial pressure. Thus, although catecholamines improve hemodynamics in experimental tamponade, the heart is the only critical organ to which blood flow is improved. The hemodynamic benefits of catecholamine administration to patients may be more limited than previous experimental studies have suggested. (4) Hoit BD, Gabel M, Fowler NO Hemodynamic efficacy of rapid saline infusion and dobutamine versus saline infusion alone in a model of cardiac rupture. J Am Coll Cardiol 1990 Dec;16(7):1745-9 Despite recent reports describing survival after cardiac rupture, the effectiveness of circulatory support while awaiting definitive surgical treatment is controversial. To assess the efficacy of volume expansion and pharmacologic support in cardiac tamponade due to cardiac rupture, a model of hemorrhagic cardiac tamponade was developed and treatment with rapid saline infusion and dobutamine was compared with rapid saline infusion alone in 15 closed chest dogs. A right ventricular wound of reproducible size was produced by deflating an aortic valvuloplasty balloon that had previously been passed by way of the internal jugular vein into the pericardial space and through a stab wound in the right ventricular free wall. Hemodynamic values were compared at baseline, during tamponade and after a rapid infusion (1 liter at 100 ml/min) of either saline solution alone or saline solution plus dobutamine (20 micrograms/kg per min). Atrial and pericardial pressures increased significantly in both groups. Mean arterial pressure, cardiac output and stroke volume increased with combined saline and dobutamine infusion to values similar to those at baseline (91 +/- 19%, 114 +/- 43% and 94 +/- 37% of baseline, respectively). In contrast, saline infusion alone caused a small increase in cardiac output but failed to significantly increase mean arterial pressure or stroke volume (76.8 +/- 14.2%, 55 +/- 18% and 51 +/- 17% of baseline, respectively). Combined rapid infusion of saline solution and dobutamine infusion has a more beneficial hemodynamic effect and may be more effective than rapid saline infusion alone in resuscitating patients with hemorrhagic cardiac tamponade due to cardiac rupture. (5) Zhang H, Spapen H, Vincent JL Effects of dobutamine and norepinephrine on oxygen availability in tamponade-induced stagnant hypoxia: a prospective, randomized, controlled study. Crit Care Med 1994 Feb;22(2):299-305 OBJECTIVES: To explore the effects of dobutamine and norepinephrine on the global cardiovascular response and on the relationship between oxygen uptake (VO2) and oxygen delivery (DO2) during an acute reduction in blood flow associated with tamponade. DESIGN: Prospective, randomized, controlled acute intervention study. SETTING: University intensive care unit (ICU) laboratory. SUBJECTS: Twenty healthy, anesthetized mongrel dogs, weighing 19 to 28 kg. INTERVENTIONS: Six dogs served as control, seven dogs were given 10 micrograms/kg/min of dobutamine and another seven dogs were given 1 microgram/kg/min of norepinephrine. Data were collected at graded incremental levels of intrapericardial pressure. MEASUREMENTS AND MAIN RESULTS: VO2 was derived from expired gas analysis and DO2 was calculated from the product of thermodilution cardiac index and arterial oxygen content. In each animal, two catheters were inserted into the pericardium to induce tamponade by saline infusion and to measure the intrapericardial pressure. The critical Do2 value, below which VO2 decreased, was found at 9.4 +/- 1.3 mL/kg/min in the control animals. When DO2 decreased to below this critical value, lactic acidosis developed. Dobutamine and norepinephrine, at the dose that was administered, significantly increased cardiac index and DO2. Critical DO2 was slightly higher in the treated than in the control animals (12.1 +/- 1.6 mL/kg/min in dobutamine and 13.2 +/- 0.9 mL/kg/min in norepinephrine, NS). VO2 at critical DO2 was significantly higher in the treated groups than in the control group (7.7 +/- 1.1 mL/kg/min in the dobutamine group and 7.9 +/- 0.9 mL/kg/min in the norepinephrine group vs. 5.4 +/- 0.4 mL/kg/min in control, both p < .01). There was no significant difference in the critical oxygen extraction ratio and the slope of the supply-dependent line between the three groups. In dobutamine-treated animals, cardiac index, DO2, and VO2 were better maintained for any intrapericardial pressure than in the other groups. Critical intrapericardial pressure, at which VO2 started to decrease, was significantly higher in the dobutamine-treated group than in the control group (13.8 +/- 2.3 vs. 9.3 +/- 1.2 mm Hg, p < .05). At critical DO2, the mean blood lactate concentration was also lower in the dobutamine-treated animals than in the other animals (2.1 +/- 0.3 vs. 4.1 +/- 0.7 mmol/L in control and 3.8 +/- 0.4 mmol/L in the norepinephrine group, both p < .05). CONCLUSIONS: During low-flow states associated with tamponade, both dobutamine and norepinephrine at the dose used increased cardiac index, DO2, and VO2, but dobutamine delayed the onset of tissue hypoxia by further increasing blood flow and oxygen availability. In the conditions of the present study, neither agent significantly influenced the oxygen extraction capabilities of the body.