Circulation
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Comparative Study Clinical Trial Controlled Clinical Trial
Milrinone and dobutamine in severe heart failure: differing hemodynamic effects and individual patient responsiveness.
Milrinone and dobutamine were compared in 15 patients with New York Heart Association functional class III and IV congestive heart failure. Dobutamine and milrinone were administered intravenously according a graded titration schedule up to maximum doses (14 micrograms/kg/min and 75 micrograms/kg, respectively) or until increased ventricular ectopy or a reduction in left ventricular end-diastolic pressure to 10 mm Hg or less occurred. Although both agents markedly increased cardiac index, milrinone caused a significantly greater reduction in left and right heart filling pressures and mean arterial pressure than did dobutamine, and for any given increase in dP/dt, milrinone caused a greater reduction in systemic vascular resistance than did dobutamine. ⋯ The positive inotropic responses of individual patients to dobutamine (5 micrograms/kg/min) and milrinone (25 micrograms/kg) were compared. The increases in dP/dt with both agents were variable, and correlated poorly (r = .50; p = .059). Patients were divided into two groups: Group I consisted of eight patients in whom the ratio of the increase in dP/dt with dobutamine vs milrinone was greater than 1.0 (good dobutamine responders); group II consisted of seven patients in whom this ratio was less than 1.0 (poor dobutamine responders).(ABSTRACT TRUNCATED AT 250 WORDS)
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Whether blood flow during cardiopulmonary resuscitation (CPR) results from intrathoracic pressure fluctuations or direct cardiac compression remains controversial. From modeling considerations, blood flow due to intrathoracic pressure fluctuations should be insensitive to compression rate over a wide range, but dependent on the applied force and compression duration. If direct compression of the heart plays a major role, however, flow should be dependent on compression rate and force, but above a threshold, insensitive to compression duration. ⋯ There was, however, a significant increase in perfusion pressures when rate was increased from 60 to 150/min at a constant duration of 45%. Thus, vital organ perfusion pressures and flow during manual external chest compression are dependent on the duration of compression, but not on rates of 60 or 150/min. These data are similar to those observed for vest CPR, where intrathoracic pressure is manipulated without sternal displacement, but opposite of those observed for direct cardiac compression.(ABSTRACT TRUNCATED AT 400 WORDS)