Cardiac index

Increasing cardiac index to predefined supranormal levels has not been found to improve outcome... 

Cardiac index (Cl) greater than 2.2 L/minute per square meter, pulmonary capillary wedge pressure (PCWP) less than 18 mm Hg... 

Is the patient hemodynamically stable If not, admit to the intensive care unit for ongoing treatment and monitoring. A PA catheter (or CVP catheter) should be inserted by trained medical personnel. Monitor PAOP to a goal pressure of 14 to 18 mm Hg and minimum cardiac index of 2.2 L/minute per square meter (alternatively CVP 8 to 15 cm H20). 

Norepinephrine is a potent a-adrenergic agent with less pronounced P-adrenergic activity. Doses of 0.01 to 3 mcg/kg per minute can reliably increase blood pressure with small changes in heart rate or cardiac index. Norepinephrine is a more potent agent than dopamine in refractory septic shock.24,27-28... 

Dobutamine is a P-adrenergic inotropic agent that can be utilized for improvement of cardiac output and oxygen delivery. Doses of 2 to 20 mcg/kg per minute increase cardiac index however, heart rate increases significantly. Dobutamine should be considered in septic patients with adequate filling... 

Epinephrine is a nonspecific a- and P-adrenergic agonist. Epinephrine can increase cardiac index and produce significant peripheral vasoconstriction. However, it can also increase lactate levels and impair blood flow to the splanchnic system. Because of these undesirable effects, epinephrine should be reserved for patients who fail to respond to traditional therapies.24,27-28... 

Cardiac index Cardiac output (see below) normalized for body surface area (cardiac index = cardiac output/body surface area). 

It has been shown that CGRP is released into the circulation during the development of human sepsis and septic shock (A8). Plasma CGRP levels correlated with the APACHE II score as well as with cardiac index and systemic vascular re-sistence index. There is also a relationship between the initial plasma CGRP levels and the severity of the disease at the time of admission to the ICU. Plasma CGRP levels are related to the hemodynamic changes seen early in septic shock. 

Distinguish among cardiac output, cardiac reserve, and cardiac index... 

The size of the body is another factor that determines cardiac output. Healthy young men have a cardiac output of about 5.5 to 6.0 1/min the cardiac output in women averages 4.5 to 5.0 1/min. This difference does not involve gender per se, but rather the mass of body tissue that must be perfused with blood. Cardiac index normalizes cardiac output for body size and is calculated by the cardiac output per square meter of body surface... 

Cardiac output also varies with age. Expressed as cardiac index, it rapidly rises to a peak of more than 4 1/min/m2 at age 10 and then steadily declines to about 2.4 1/min/m2 at the age of 80. This decrease in cardiac output is a function of overall metabolic activity and therefore indicative of declining activity with age. 

Invasive hemodynamic monitoring should be considered in patients who are refractory to initial therapy, whose volume status is unclear, or who have clinically significant hypotension such as systolic BP <80 mm Hg. Such monitoring helps guide treatment and classify patients into four specific hemodynamic subsets based on cardiac index and pulmonary artery occlusion pressure (PAOP). Refer to textbook Chap. 16 (Heart Failure) for more information. 

Dobutamine increases cardiac index because of inotropic stimulation, arterial vasodilation, and a variable increase in heart rate. It causes relatively little change in mean arterial pressure compared with the more consistent increases observed with dopamine. 

During IV administration, milrinone increases stroke volume (and cardiac output) with little change in heart rate. It also decreases PAOP by venodilation and thus is particularly useful in patients with a low cardiac index and an elevated LV filling pressure. However, this decrease in preload can be hazardous for patients without excessive filling pressure, leading to a decrease in cardiac index. 

Sodium nitroprusside is a mixed arterial-venous vasodilator that acts directly on vascular smooth muscle to increase cardiac index and decrease venous pressure. Despite its lack of direct inotropic activity, nitroprusside exerts hemodynamic effects that are qualitatively similar to those of dobutamine and milrinone. However, nitroprusside generally decreases PAOP, SVR, and blood pressure more than those agents do. 

IABP support increases cardiac index, coronary artery perfusion, and myocardial oxygen supply accompanied by decreased myocardial oxygen demand. 

Cardiac index and blood pressure must be sufficient to ensure adequate organ perfusion, as assessed by alert mental status, creatinine clearance sufficient to prevent metabolic azotemic complications, hepatic function adequate to maintain synthetic and excretory functions, a stable heart rate and rhythm, absence of ongoing myocardial ischemia or infarction, skeletal muscle and skin blood flow sufficient to prevent ischemic injury, and normal arterial pH (7.34 to 7.47) with a normal serum lactate concentration. These goals are most often achieved with a cardiac index greater than 2.2 L/min/m2, a mean arterial blood pressure greater than 60 mm Hg, and PAOP of 25 mm Hg or greater. 

Dopamine in doses greater than 5 mcg/kg/min is used to support blood pressure and to increase cardiac index. Low dose dopamine (1 to 5 meg/ kg/min) is not effective to increase renal and mesenteric perfusion. 

Administration by inhalation has been explored by Brilli [124], mentioned previously for his work with NONOates. Here he uses one of these same NONOates, DMAEP/NO (see Fig. 8.11), in aerosol form. When administered in an aerosolized state, DMAEP/NO again shows selective pulmonary vasodilation in a porcine model. This is achieved without affecting the systemic vascular resistance index (SVRI) or the cardiac index (Cl). Work from the same year by Adrie et al. [125] compared aerosolized DEA/NO with aerosolized SNP and inhaled NO, in sheep. As the NONOate has a short half-life (2.1 min), it was predicted that this would be a selective pulmonary vasodilator. However, compared with inhaled NO this was not observed, though SNP... 

Nekooeian, A.A. and Tabrizchi, R., Effects of adenosine a2 receptor agonist, cgs 21680, on blood pressure, cardiac index and arterial conductance in anaesthetized rats, Eur. J. 

The IV administration of propafenone is accompanied by an increase in right atrial, pulmonary arterial, and pulmonary artery wedge pressures in addition to an increase in vascular resistance and a decrease in the cardiac index. A significant decrease in ejection fraction may be observed in patients with preexisting left ventricular dysfunction. In the absence of cardiac abnormalities, propafenone has no significant effects on cardiac function. 

Dofetilide does not significantly alter the mean arterial blood pressure, cardiac output, cardiac index, stroke volume index, or systemic vascular resistance. There is a slight increase in the delta pressure/delta time (dP/dt) of ventricular myocytes. 

J.P. Meinhardt, U. Friess, H.J. Bender, R.B. Hirschl, M. Quintel, Relationship among cardiac index, inspiration/expiration ratio, and perfluorocarbon dose during partial liquid ventilation in an oleic acid model of acute lung injury in sheep, J. Pediatr. Surg. 40 (2005) 1395-1403. 

It is characterized by severe, persisting pain, shock and hypotension with possible development of arrhythmias and is due to severe depression of systolic cardiac performance, systolic arterial pressure is below 80 mm Hg, low cardiac index, ventricular filling pressure is elevated and pulmonary edema may or may not be evident. The most frequent cause is infarction involving more than fourty percent of the left ventricular myocardiam, leading to a severe reduction in left ventricular contractility contradictively and failure of the left ventricular pump. 

---