News - Part 3

Effect of Dobutamine on Lung Microvascular Fluid Flux in Sheep with “Sepsis Syndrome”: Experimental ProtocolExperimental Protocol
Baseline studies were performed over a 120-minute period approximately three to four days after recovery from preliminary surgery. Pulmonary lymph was collected and measured for volume every 15 minutes; lymph was pooled at the end of the two-hour baseline period for measurement of total protein and albumin. At the midpoint of this baseline “nonseptic” study, we measured systemic and pulmonary arterial pressures, as well as cardiac output. Blood was drawn from the arterial line and distal port of the right-heart catheter for chemical analysis, hematologic studies, and measurement of arterial and central venous blood gas levels. Dobutamine (500 mg dissolved in 500 ml of 5 percent dextrose in water) was then sequentially administered at two doses (5μg/kg/min and 10μg/kg/ min) for a 60-minute infusion period with each. The first 15 to 30 minutes of infusion at each dose represented a period of equilibration. Pulmonary lymph was collected and measured for volume during each of the last two 15-minute periods of infusion; it was subsequently pooled for measurement of total protein and albumin. Blood was drawn for hematologic studies, chemical analysis, and blood gas levels at the end of each of the last two 15-minute periods of infusion. We also repeated measurement of the cardiac output, and systemic and pulmonary arterial pressures at the same time. Therefore, values reported during infusion of the drug at both doses represent the average of two measurements obtained during two timed 15-minute periods of collection.
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Experimental Preparation
Ten mature Suffolk sheep, weighing 30 to 40 kg (0.9 to 1.2 m2 of body surface area), were prepared with chronic lymph fistulae using a modification of the technique described by Staub et al. Before study the sheep were premedicated with atropine sulfate and were then anesthetized and intubated. We cannulated the aorta with a nonheparinized Silastic catheter (medical grade tubing; 0.125 outer diameter; Dow Corning) and the pulmonary artery with a No. 8 French, right-heart flow-directed thermodilution catheter (Edwards model 93A-131). The right-heart catheter position was confirmed by the presence of typical pressure recordings. With the balloon inflated, a pulmonary arterial wedge tracing was documented. The balloon was then deflated, and the catheter was flushed for the duration of the experiment with a continuous infusion of 5 percent dextrose in water, to which 1,000 units of heparin had been added (1.0 ml/hr). Read the rest of this entry »

Dobutamine had no net effect on pulmonary fluid flux in the nonseptic studies. In contrast, its effects in the septic state were inconsistent. At a dose of 5μg/kg/ min, a modest (24 percent) increase in QL was demonstrable when compared to baseline, while no significant change was evident with the 10μLg/kg/min dose; with an increase in QL, [L/P]TP ratios fell. Reasons for an increase in QL at the lower infused dose might include an effect of dobutamine to increase either the Pmv2 or the surface area of the lung s microvasculature across which fluid exchange occurs. Since we found no relationship between changes in cardiac output and Ql, we would conclude that changes in surface area were not likely to be responsible for the slight increase noted in QL Therefore, the data are most consistent with an interpretation that a “hydrostatic” effect was primarily responsible for the changes documented in pulmonary QL with low-dose dobutamine infusion. Since the pulmonary arterial wedge pressure was significantly elevated from baseline at this dose, without any concurrent change in the left atrial pressure, it is conceivable that a pressure gradient was established between the left atrium and the lungs microvascular exchanging membrane, and that such was thereby responsible for the modest increase in QL observed during low-dose dobutamine infusion. Read the rest of this entry »

Effect of Dobutamine on Lung Microvascular Fluid Flux in Sheep with “Sepsis Syndrome”: Lungs microvascularSince dobutamine has been recommended as an adrenergic receptor agonist which might be used in preference to dopamine when systemic flows require pharmacologic support in ARDS, we studied its effects on fluid flux in an animal model of peritonitis which is characterized by lung microvascular injury. This model seems more representative of early clinical sepsis than are endotoxic models, since it is characterized by a high systemic flow and low peripheral resistance state, with maintenance of systemic pressures. We evaluated the effects of dobutamine on microvascular fluid exchange in the lung of chronically cannulated sheep by using changes in the magnitude of Ql to reflect changes in water flux and using changes in the CLP to represent changes in protein flux. Read the rest of this entry »

The flow-dependency of systemic Vo2, which is frequently demonstrable when ARDS complicates the “sepsis syndrome,” may clinically dictate the use of P-adrenergic receptor agonists when cardiac output (hence systemic oxygen transport) is not deemed sufficient to satisfy peripheral oxygen needs. Theoretically, the administration of (3-adrenergic receptor agonists could increase pulmonary microvascular fluid flux in ARDS and thereby lead to further edema; however, we found in this study that dobutamine did not substantially increase QL in an animal model of sepsis-induced microvascular pulmonary injury when infused at a dose of 10μg/kg/min, although a modest increase (+ 24 percent) was demonstrable when dobutamine was infused at a lower dose. Read the rest of this entry »

Length of Stay and Deaths
Analysis of Medicare MICU vs nonMICU indicates an average length of stay of 24.9 days for patients receiving medical intensive care compared with 9.9 days for nonMICU patients in 1985. The average number of days in the MICU was 5.4 days (22 percent of the average total stay of 24.9 days in 1984). The average number of days in the MICU in 1985 was 6.8 days (26 percent of the total average stay). In 1984, average length of stay in the MICU for Medicare patients ranged from 1.5 to 9.1 days across the five highest volume MDCs, in comparison with a range of 21.9 to 29.1 total length of stay for these groups. In 1985, the average length of stay in the MICU ranged from 3.7 to 10.2 days across the five highest volume MDCs, in comparison with a range of 13.8 to 32.5 total length of stay for these groups. Medicare MICU patients who died during their hospital stay numbered 112 in 1984 and 95 in 1985, or 42 and 39.4 percent of the total, respectively. Of these, 59 died while in the MICU in 1984 and 63 in 1985. A chi-square test gave no significant difference in mortality rate or distribution of DRG assignments, with p values of 0.56 and 0.88, respectively. Read the rest of this entry »

Impact of Diagnosis-Related Groups' Prospective Payment on Utilization of Medical Intensive Care: ResultsTable 2 summarizes the financial impact of Medicare payments for patients receiving medical intensive care. In 1984, the average projected DRG payment for the 267 Medicare patients treated in the MICU was $10,683 per discharge. The average DRG weight per discharge was 1.94, in contrast to the overall hospital case mix index for medicare patients of 1.78. Total payments (including outlier payments) of $3,230,099 vs costs of $5,845,328 resulted in a total loss of $2,615,229. Payment amounted to only 55 percent of costs. In 1985, the average projected DRG payment for 241 Medicare patients treated in MICU was $10,605 per discharge. The average DRG weight was 1.90, in contrast to overall hospital case mix index of 1.85. Total payments (including outlier payments) of $2,982,697 vs costs of $6,383,942 resulted in a net loss of $3,401,245. Payment amounted to only 47 percent of costs. Payment and costs are for all days of the hospital stay, in both the MICU and other units. Read the rest of this entry »

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