PubMed · 5801864
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R C Hansoti. 1969-04-01. Circulatory shock.. https://pubmed.ncbi.nlm.nih.gov/5801864/
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OBJECTIVES: We investigated the interaction of heart rate (HR), temperature and contractility using a validated load independent method. BACKGROUND: Temperature manipulation is an integral part of cardiac surgery, and postoperative hypothermia is extremely common. Myocardial contraction is a series of enzymatic and physico-chemical reactions that may be differentially affected by temperature. METHODS: Ten patients undergoing coronary artery bypass grafting were studied during moderately hypothermic cardiopulmonary bypass. After conduit procurement and heparinization but before grafting, the patient was placed on cardiopulmonary bypass and rewarmed to 37 degrees C, and the left ventricle (LV) was instrumented with a conductance catheter allowing continuous pressure and volume measurement. The LV pressure volume relationship was examined to assess the contractility at 37, 35, 33 and 31 degrees C, with fixed atrial pacing (100 beats/min) in five patients and at 80 and 120 beats/min, at 33 and 37 degrees C in five patients. RESULTS: At a HR of 100 beats/min, lower temperature resulted in a highly significant decrease in maximal elastance (100% at 37 degrees C, 29 +/- 3.5% at 31 degrees C, p < 0.0001). At 37 degrees C, increasing HR increased contractility (80 beats/min 100%, 120 beats/min 205.9%, p = 0.0021); however, at 33 degrees C contractility fell with increasing HR (80 beats/min 100%, 120 beats/min, 53.7%, p = 0.0014). CONCLUSIONS: At normothermia LV contractility has a direct relationship with HR. In hypothermic conditions this relationship inverses. Clinical strategies maintaining higher HRs at colder temperatures result in reduced contractility. These factors are important in the management of cardiac surgical patients.
OBJECTIVES: We assessed an air-blood-saline mixture for Doppler measurement of pulmonary artery systolic pressure (PASP) and the mechanism of enhancement of the Doppler signal by this mixture. BACKGROUND: Underestimation of PASP by Doppler echocardiography occurs with inadequate continuous wave (CW) signals of tricuspid regurgitation (TR). METHODS: We assessed in vitro the diameter and concentration of microbubbles of agitated air-saline mixture, air-blood-saline mixture and 10% air-10% plasma-80% saline mixture immediately, 5, 10 and 20 s after agitation. In 20 patients, PASP was estimated by Swan-Ganz catheter and CW Doppler of TR: 1) without contrast injection; 2) with intravenous injection of 10% air-90% saline; and 3) 10% blood-10% air-80% saline mixture. RESULTS: Compared to air-saline, addition of blood or plasma to the air-saline solution significantly increased the concentration of microbubbles (p < 0.001). The air-blood-saline (26.7 +/- 7.2 microm) and air-plasma-saline mixture (25.3 +/- 7.4 microm) had smaller microbubbles than air-saline mixture (31.6 +/- 8.2 microm) (p < 0.001). The correlation between Doppler- and catheter-measured PASP at baseline (r = 0.64) improved with agitated air-saline (r = 0.86). With the air-blood-saline mixture, the correlation further improved (r = 0.92) and the best limits of agreement were obtained. CONCLUSIONS: The combination of the patient's own blood is a method of making a sterile solution of numerous small microbubbles for injection into the right-sided cardiac chambers. Clinically, the air-blood-saline mixture is easily prepared at bedside and is superior to the air-saline mixture in assessing PASP in patients with inadequate CW Doppler signals.
PURPOSE: Dopamine continues to be used for preventing and treating acute renal failure. We determined the effects of dopamine on postoperative renal function in patients with a solitary kidney undergoing partial nephrectomy. MATERIALS AND METHODS: We performed a prospective randomized controlled study at a tertiary care referral center involving 24 patients with a solitary kidney undergoing partial nephrectomy secondary to malignancy. Patients were randomized to receive dopamine (11) [corrected] or no dopamine (13) [corrected]. Intraoperatively those assigned to the dopamine group received a 3 microg./kg. per minute dopamine infusion. Patients in each group received an adequate amount of fluid to maintain good urine production, systemic blood pressure and central venous pressure. Serum electrolytes, blood urea nitrogen, creatinine, serum and urine osmolality, and urine output were measured at baseline, intraoperatively and through postoperative day 4. Preoperatively and postoperatively renal blood flow and the glomerular filtration rate were measured. RESULTS: In the 2 groups blood urea nitrogen and serum creatinine increased postoperatively. Although the degree of this increase showed a trend to be lower in the dopamine group, the difference did not reach statistical significance. There was no difference in renal blood flow or the glomerular filtration rate in the treatment groups. CONCLUSIONS: Administering dopamine to patients with a solitary kidney undergoing partial nephrectomy provided no renoprotective effect.