British journal of anaesthesia
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Randomized Controlled Trial Clinical Trial
Influence of hypertonic volume replacement on the microcirculation in cardiac surgery.
We have studied the effects of two types of volume replacement on the microcirculation in an open, controlled study in 45 patients undergoing aorto-coronary bypass grafting whose pulmonary capillary wedge pressure (PCWP) was less than 5 mm Hg. Hypertonic saline prepared in hydroxyethylstarch solution (HS-HES, n = 15) and 6% HES 200/0.5 solution (6% HES; n = 15) were infused randomly before operation in order to double the PCWP. Patients not given an infusion served as controls (n = 15). ⋯ Plasma viscosity decreased after infusion of HS-HES and increased slightly in control patients (+4%). In comparison with the 6% HES and particularly with the control group, LDF was significantly greater after infusion of HS-HES (forearm +80%; forehead +28%). LDF during CPB and thereafter was always greater than baseline values in the HS-HES group, whereas after bypass LDF was reduced in the 6% HES (-5%) and particularly in the control patients (-30%).(ABSTRACT TRUNCATED AT 250 WORDS)
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We have studied the haemodynamic effects of i.v. milrinone, a new phosphodiesterase inhibitor, in patients with low cardiac output after cardiac surgery. Thirty-five patients with a cardiac index (Cl) less than 2.5 litre min-1 m-2 and a pulmonary capillary wedge pressure (PCWP) greater than 8 mm Hg were given a loading dose of milrinone 50 micrograms kg-1 followed by an infusion at one of three rates: 0.375 micrograms kg-1 min-1, 0.5 micrograms kg-1 min-1 or 0.75 micrograms kg-1 min-1 for 12 h. After 1 h there were increases in Cl (35%) (P less than 0.001), heart rate (13%) (P less than 0.01) and stroke volume index (19%) (P less than 0.005). ⋯ The haemodynamic improvements were sustained throughout the infusion period. Milrinone was tolerated well: three patients developed tachycardia greater than 125 beat min-1, one patient developed atrial fibrillation and one patient had a short run of atrial bigemini. We conclude that milrinone is a useful agent in the treatment of patients with a reduced cardiac output after cardiac surgery.
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Randomized Controlled Trial Clinical Trial
Propofol and midazolam act synergistically in combination.
We have studied interactions between i.v. propofol and midazolam for induction of anaesthesia in 200 unpremedicated female patients undergoing elective gynaecological surgery. Using end-points of "hypnosis" (loss of response to verbal command) and "anaesthesia" (loss of response to a 5-s transcutaneous tetanic stimulus), we determined dose-response curves for propofol and midazolam alone and in combination. ⋯ The reduction in arterial pressure at induction was the same for the combination as for the individual agents. The cause of the synergism was not clear, but may have been interaction at CNS GABAA receptors.
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Serial measurements of haemodynamic variables were performed at 1-min intervals in nine ASA I, unpremedicated patients before and for 5 min after induction of anaesthesia with propofol 2.5 mg kg-1. End-tidal carbon dioxide concentration was maintained within the normal range. Stroke volume and left ventricular function were measured by Doppler and cross-sectional echocardiography at the aortic valve. ⋯ There was a decrease at all time points in systolic, mean and diastolic arterial pressure. There was an initial increase in heart rate and cardiac output, with a subsequent decrease to less than baseline. There was an initial decrease in systemic vascular resistance followed by partial recovery, and a delayed decrease in left ventricular function as measured by peak aortic blood flow velocity and acceleration.