Hemodynamic management in clinical acute hypoxemic respiratory failure. Dopamine vs dobutamine

Analytic Reviews : Hemodynamic Management of the Adult Respiratory Distress Syndrome

Hemodynamic management is an essential aspect of the care of patients with adult respiratory distress syn drome (ARDS). On the basis of current knowledge, our proposed goals of management are to maximize pe ripheral oxygen delivery while attempting to minimize further lung damage or dysfunction. The major patho physiologic abnormalities of ARDS are an increased lung vascular permeability, right-to-left intrapulmonary shunting, and pulmonary vascular resistance. These abnormalities must be understood to select the proper therapy. Although all patients with ARDS share these abnormalities, they differ in their associated clinical conditions and underlying cardiovascular status. Be cause each ARDS patient may respond differently to therapy, hemodynamic management must be selected empirically with the goal of therapy as a guide. We have considered available therapeutic options including posi tive end-expiratory pressure, volume depletion, volume expansion, vasopressors, and vasodilators. In the future hemodynamic management of patients with ARDS will likely change as better methods of patient assessment and treatment are developed.

Pediatric Bone Marrow Transplantation: Intensive Care Management

Bone marrow transplantation (BMT) has assumed in creasing importance in the treatment of bone marrow failure, hematopoietic malignancies, congenital immuno deficiencies, and solid tumors. Children undergoing BMT are at high risk for infection and hemorrhage dur ing the period of aplasia. In addition, life-threatening complications of circulatory, pulmonary, gastrointesti nal, hepatic, and renal function are common and fre quently require intensive supportive care. This review provides an overview of pediatric BMT that focuses on management problems relevant to intensive care. Thor ough pretransplantation assessment of underlying organ dysfunction is mandatory before undertaking BMT. The complications associated with preconditioning regi mens that use total body irradiation and high doses of ablative chemotherapy are described. Finally, problems involving individual organs are discussed by systems. The challenge of improving the results of BMT in the treatment of childhood malignant and hematopoietic disorders depends, in large part, on successful preven tive measures and good management of complications that occur immediately before and within the first 100 days after transplantation. As BMT is indicated for treat ment of an increasing number of diseases, more patients will require the care of intensivists familiar with trans plantation-related complications.

The effects of dobutamine and dopamine on intrapulmonary shunt and gas exchange in healthy humans

The development of intrapulmonary shunts with increased cardiac output during exercise in healthy humans has been reported in several recent studies, but mechanisms governing their recruitment remain unclear. Dobutamine and dopamine are inotropes commonly used to augment cardiac output; however, both can increase venous admixture/shunt fraction (Qs/Qt). It is possible that, as with exercise, intrapulmonary shunts are recruited with increased cardiac output during dobutamine and/or dopamine infusion that may contribute to the observed increase in Qs/Qt. The purpose of this study was to examine how dobutamine and dopamine affect intrapulmonary shunt and gas exchange. Nine resting healthy subjects received serial infusions of dobutamine and dopamine at incremental doses under normoxic and hyperoxic (inspired O(2) fraction = 1.0) conditions. At each step, alveolar-to-arterial Po(2) difference (A-aDo(2)) and Qs/Qt were calculated from arterial blood gas samples, intrapulmonary shunt was evaluated using contrast echocardiography, and cardiac output was calculated by Doppler echocardiography. Both dobutamine and dopamine increased cardiac output and Qs/Qt. Intrapulmonary shunt developed in most subjects with both drugs and paralleled the increase in Qs/Qt. A-aDo(2) was unchanged due to a concurrent rise in mixed venous oxygen content. Hyperoxia consistently eliminated intrapulmonary shunt. These findings contribute to our present understanding of the mechanisms governing recruitment of these intrapulmonary shunts as well as their impact on gas exchange. In addition, given the deleterious effect on Qs/Qt and the risk of neurological complications with intrapulmonary shunts, these findings could have important implications for use of dobutamine and dopamine in the clinical setting.

Abnormal response to inotropic stimulation in young asymptomatic type I diabetic patients demonstrated by serial gated myocardial perfusion SPECT imaging

PURPOSE

In subjects without underlying cardiac disease dobutamine is known to enhance systolic LV function and LV relaxation. As end-systolic (ES) and end-diastolic (ED) volumes (V) can be derived from gated SPECT we intent to study these volumes and their response to dobutamine in order to have a better understanding of the mechanism by which stroke volume (SV) increases during dobutamine infusion. We intent to do this in normal controls and in young diabetic subjects.

METHODS

After injection of sestamibi, serial gated SPECT were obtained at baseline, and during low doses of dobutamine infusion in 12 asymptomatic type I diabetic patients, and in 12 age matched controls. LV EDV, ESV, SV and EF were calculated with the QGS program.

RESULTS

Gated SPECT showed comparable LV EF and SV in both groups at rest. There was a significant increase in LVEF and SV during dobutamine infusion but in the diabetic patients the increase in SV was due to a decrease in ESV from 25+/-5 to 20+/-6 ml/m2 (p=0.002) and no change in EDV. In normal controls, the increase in EF was due to an increase in EDV from 69+/-10 to 73+/-12 ml/m2 (p=0.002) with no significant change in ESV.

CONCLUSION

These data confirm the presence of subclinical abnormalities of diastolic function in asymptomatic type I diabetic patients and show differences in adaptation to inotropic stimulation in order to preserve the increase in stroke volume and LV ejection fraction.

Global end-diastolic volume as an indicator of cardiac preload in patients with septic shock

STUDY OBJECTIVE

To assess the value of the global end-diastolic volume (GEDV) evaluated by transpulmonary thermodilution as an indicator of cardiac preload.

DESIGN

Prospective clinical study.

SETTING

Medical ICU of a university hospital (20 beds).

PATIENTS

Thirty-six patients with septic shock.

INTERVENTIONS

Volume loading and dobutamine infusion.

MEASUREMENTS AND RESULTS

Hemodynamic parameters were evaluated in triplicate by the transpulmonary thermodilution technique: (1) before and after 66 fluid challenges in 27 patients, and (2) before and after 28 increases in dobutamine infusion rate in 9 patients. Volume loading induced a significant (p < 0.001) increase in central venous pressure (CVP) from 10 +/- 4 to 13 +/- 4 mm Hg, in GEDV index from 711 +/- 164 to 769 +/- 144 mL/m(2), in stroke volume index (SVI) from 36 +/- 12 to 42 +/- 12 mL/m(2), and in cardiac index (CI) from 3.4 +/- 1.1 to 3.9 +/- 1.2 L/min/m(2) (mean +/- SD). Changes in GEDV index were correlated (r = 0.72, p < 0.001) with changes in SVI, while changes in CVP were not. The increase in SVI was > 15% in 32 of 66 instances (positive response). The preinfusion GEDV index was lower (637 +/- 134 mL/m(2) vs 781 +/- 161 mL/m(2), p < 0.001) in the cases of positive response, and was negatively correlated with the percentage increase in GEDV index (r = - 0.65, p < 0.001) and in SVI (r = - 0.5, p < 0.001). Dobutamine infusion induced an increase in SVI (32 +/- 11 mL/m(2) vs 35 +/- 12 mL/m(2), p < 0.05) and in CI (2.8 +/- 0.6 L/min/m(2) vs 3.2 +/- 0.6 L/min/m(2), p < 0.001) but no significant change in CVP (13 +/- 3 mm Hg vs 13 +/- 3 mm Hg) and in GEDV index (823 +/- 221 mL/m(2) vs 817 +/- 202 mL/m(2)).

CONCLUSION

In patients with septic shock, our findings demonstrate that, in contrast to CVP, the transpulmonary thermodilution GEDV index behaves as an indicator of cardiac preload.

Effect of a catecholamine-induced increase in cardiac output on extravascular lung water

OBJECTIVE

To determine the influence of dopamine- and dobutamine-induced increases in cardiac output on the extravascular lung water in an experimental model of pulmonary edema.

DESIGN

Animal experimental study.

SETTING

Animal experimental laboratory of a tertiary hospital.

SUBJECTS

Mixed-race pigs (n = 20) weighing 28-32 kg.

INTERVENTIONS

After the animals were anesthetized and tracheotomized, they were injected with 0.1 mL/kg of oleic acid, producing a pulmonary edema by increased permeability. The animals then were randomized into two groups: Group I (n = 10) received no medication to alter cardiac output and remained on mechanical ventilation during the 240 mins of the experiment; group II (n = 10) received a continuous infusion of dopamine and dobutamine to produce a cardiac output increase of >or=30% the basal value and underwent the same mechanical ventilation regimen as group I.

MEASUREMENTS AND MAIN RESULTS

Hemodynamic and respiratory variables were measured at 0 (baseline) and 30, 60, 120, 180, and 240 mins after the infusion of oleic acid. At 30 mins, the cardiac output of group II (5.40 +/- 0.94 L/min) was significantly (p < .005) higher than that of group I (3.65 +/- 1.02 L/min), and a similar significant increase was recorded at all measurement times until the end of the experiment. The mean pulmonary arterial pressure was similar in both groups except that at 240 mins it was significantly higher in group I (normal cardiac output) than in group II (high cardiac output; 34.9 +/- 7.9 mm Hg vs. 27.2 +/- 3.8 mm Hg, p = .01). The extravascular lung water was calculated by gravimetric method after the death of the animal. The extravascular lung water of group I (13.8 +/- 3.6 mL/kg) did not significantly differ from that of group II (11.5 +/- 4.0 mL/kg).

CONCLUSIONS

An increase in cardiac output experimentally produced by the infusion of dopamine and dobutamine does not modify the amount of extravascular lung water.

The role of the vasculature in regulating venous return and cardiac output: historical and graphical approach

PURPOSE

To review the physiology of cardiac output regulation by the peripheral vasculature. This will enable the clinician to understand and manage the complex circulatory changes in various forms of shock, and in other common altered circulatory states encountered in anaesthetic practice.

SOURCE

Articles were obtained from a Medline review (1966 to present; search terms: shock, venous return, cardiac output) and a hand search (Index Medicus). Other sources include review articles, personal files, and textbooks.

PRINCIPAL FINDINGS

At steady state, cardiac output is equal to venous return (VR). Venous return depends on mean systemic pressure (PMS), which is the pressure in the peripheral vasculature driving blood flow to the heart, right atrial pressure (PRA), and the resistance to venous return (RV). When considering VR, PRA is the downstream pressure to VR, and not simply an indirect measure of the volume status. The pressure gradient for VR is, therefore, PMS-PRA, and in a system obeying Ohm's Law, [formula: see text] Shock and other altered circulatory states cause changes in both VR and cardiac function. The circulation can be conveniently described by a venous return and a cardiac output curve. By drawing these curves for each clinical situation, a clear understanding of the altered circulatory state is obtained, and treatment options can be clearly defined.

CONCLUSION

The peripheral circulation controls cardiac output in many clinical conditions. Manipulation of the peripheral circulation is as important to the successful treatment of shock and other altered circulatory states, as is the manipulation of cardiac output.

Circulatory and diuretic effects of dopexamine infusion in low-birth-weight infants with respiratory failure

OBJECTIVE

To investigate the effects of infusion of dopexamine hydrochloride, a new synthetic catecholamine, on cardiopulmonary status and urine output in neonates with respiratory and circulatory failure.

DESIGN

Prospective clinical study with each patient serving as his own control.

SETTING

Intensive care unit (14 beds) in a 300-bed paediatric teaching hospital.

PATIENTS

Seventeen neonates with low birth weight (LBW) requiring mechanical ventilation in the first 4 days of life, who initially had two of the following symptoms: hypotension, oliguria, metabolic acidosis with base deficit >10 and failure to respond to volume loading.

INTERVENTIONS

Cardiopulmonary variables, diuresis and acid-base status were measured before and after volume loading, in patients who did not improve infusion of dopexamine was started at a dose of 2 microg kg-1 min-1 which was titrated to achieve blood pressure, urine output, and base deficit in normal range. Observations were continued for a period of 5 h.

MEASUREMENTS AND RESULTS

Systolic blood pressure increased significantly after 3 h. of dopexamine infusion and remained elevated up to the end of the study period. Diastolic and mean blood pressure increased slightly (NS). Diuresis increased significantly from the 4th h of dopexamine infusion. Arterial blood pH increased significantly from baseline at 5 h after the start of dopexamine administration. There was also a significant improvement in the PtcO2/PaO2 index.

CONCLUSION

In neonates with respiratory and circulatory failure, dopexamine increases blood pressure and improves arterial pH and urine output.

A blind, randomized comparison of the circulatory effects of dopamine and epinephrine infusions in the newborn piglet during normoxia and hypoxia

OBJECTIVE

To determine the hemodynamic responses to dopamine and epinephrine infusions in newborn piglets during normoxia and hypoxia.

DESIGN

Prospective, randomized, blind cross-over study.

SUBJECTS

Newborn piglets (n = 7).

INTERVENTIONS

Animals were acutely instrumented for measurements of cardiac output, pulmonary and systemic pressures, carotid and coronary artery blood flow, and coronary artery oxygen consumption. Dopamine at infusion rates of 2 to 16 micrograms/kg/min and epinephrine 0.2 to 1.6 micrograms/kg/min were administered during normoxia. Six piglets were similarly prepared and were then made hypoxic to an arterial O2 saturation of 45% to 50%. Epinephrine at infusion rates of 0.2 to 3.2 micrograms/kg/min and dopamine at rates of 2 to 32 micrograms/kg/min were administered in random order during hypoxia.

MEASUREMENTS AND MAIN RESULTS

During normoxia, cardiac output increased similarly with both drugs and was significantly increased by > or = 0.2 micrograms/kg/min of epinephrine and significantly increased by 8 or 16 micrograms/kg/min of dopamine. Mean arterial blood pressure was not affected by dopamine but was significantly increased by epinephrine at a rate of 1.6 micrograms/kg/min. The relative effects of the drugs on pulmonary and systemic vascular resistance differed, the pulmonary/systemic vascular resistance ratio was reduced at the higher doses of epinephrine (i.e., 0.8 and 1.6 micrograms/kg/min) and was unaffected by dopamine. Coronary artery oxygen consumption and coronary blood flow increased significantly with both medications at rates > 0.4 and 4 micrograms/kg/min, respectively. Increases of both variables were greater with epinephrine than with dopamine. Myocardial extraction ratio was unaffected by dopamine and reduced at 0.2 and 1.6 micrograms/kg/min of epinephrine. Hypoxia caused significant increases in cardiac index, systemic blood pressure, pulmonary arterial pressure, carotid artery blood flow, coronary artery blood flow, coronary oxygen consumption, coronary oxygen extraction ratio, and the pulmonary/systemic vascular resistance ratio. Mean systemic arterial blood pressure increased significantly with 1.6 and 3.2 micrograms/kg/min of epinephrine, but was not significantly affected by dopamine at any infusion rate. Cardiac index was not affected significantly by either of the medications. Thus, there was a significant increase in the calculated systemic vascular resistance index with the highest dose of epinephrine, in contrast to the slight, statistically significant, decrease in calculated systemic vascular resistance index with the highest dose of dopamine. Epinephrine significantly reduced pulmonary arterial pressures at 0.2, 0.4, and 0.8 microgram/kg/min. Dopamine had no effect on this variable. The pulmonary/systemic vascular resistance ratio was significantly reduced by epinephrine at doses of 0.2 and 3.2 micrograms/kg/min, whereas the highest dose of dopamine caused a significant increase in the pulmonary/systemic vascular resistance ratio.

CONCLUSIONS

Epinephrine infusion during normoxia increases systemic pressure more than pulmonary arterial pressure at doses > or = 8 micrograms/kg/min, and furthermore, produces a more appropriate hemodynamic profile in the presence of hypoxic pulmonary hypertension than dopamine infusion, in the acutely operated anesthetized piglet.

Haemodynamic changes in children with portal hypertension during the postoperative period

The cardiovascular changes following portosystemic shunt surgery (PSSS) in 33 children with extrahepatic portal hypertension (EPH) were studied to determine if portosystemic shunt surgery had any influence on the cardiovascular state. Haemodynamic data were obtained using two-dimensional and M-mode echocardiography, pulsed-wave Doppler and direct invasive techniques. Postoperatively all patients developed a hyperdynamic state, associated with an increase in cardiac index (CI), heart rate (HR) and a decrease in systemic vascular resistance index (SVRI). In 16 patients (group I), who preoperatively exhibited a hyperdynamic state accompanied by pulmonary hypertension, postoperative studies found an increase in acceleration time to ejection time ratio (AT/ET) in the pulmonary artery from 0.32 +/- 0.05 (mean +/- SEM) to 0.43 +/- 0.01; P < 0.01. Nine patients (group II) who were normodynamic preoperatively developed pulmonary hypertension and right ventricular (RV) dysfunction postoperatively: decrease in AT/ET from 0.42 +/- 0.02 (mean +/- SEM) to 0.32 +/- 0.01; P < 0.01 and an increase in maximal peak pulmonary artery velocity to acceleration time ratio (Vmax/AT) from 702.56 +/- 69.10 (mean +/- SEM) to 1127 +/- 105.30 cm.sec-2; P < 0.01. In eight patients (group III) who were normodynamic preoperatively and were treated with dobutamine infusions at a rate of 5 micrograms.kg-1.min-1 postoperatively, the CI was found to increase from 5.28 +/- 1.1 (mean +/- SEM) to 7.97 +/- 1.64 L.min-1.m-2; P < 0.01, left ventricular ejection fraction (LVEF) from 69.0 +/- 4.1 (mean +/- SEM) to 81.0 +/- 2.9%; P < 0.01 and AT/ET from 0.37 +/- 0.04 (mean +/- SEM) to 0.44 +/- 0.03; P < 0.01.(ABSTRACT TRUNCATED AT 250 WORDS)

Pulmonary embolism in children

Pulmonary embolism is an uncommon diagnosis in the pediatric patient, often discovered on autopsy. The mortality rate of untreated pulmonary embolism approaches 30%, and the best way to prevent death is by swift diagnosis and initiation of therapy. This article reviews the risk factors, clinical presentation, pathophysiology, diagnostic modalities, and treatment of pulmonary embolism in children.

Combined dose ratios of dopamine and dobutamine and right ventricular performance after cardiac surgery

The effect of combined administration of different dose ratios of dobutamine (DB) and dopamine (DA) (DB/DA ratio of 1:1; 1.5:0.5; 2:0; 0.5:1.5; and 0:2), with the added dose kept constant (10 micrograms/kg/min-20 micrograms/kg/min), on right ventricular function (measured by the thermal washout method with the aid of a rapid-response thermistor) was determined in ten patients after cardiac surgery (between 12 and 24 h after surgery). The following values represent the mean +/- SD of DB only and of the DB/DA-equal combination vs DA only. The DB/DA-equal or DB-dominant combination increased the right ventricular ejection fraction vs DA only (0.39 +/- 0.12 [p less than 0.01] and 0.37 +/- 0.11 [p less than 0.05], respectively, vs 0.32 +/- 0.12) and the stroke volume index (43 +/- 12 ml/m2 [p less than 0.01] and 41 +/- 15 ml/m2, respectively, vs 38 +/- 14 ml/m2) and decreased right ventricular end-diastolic pressure (RVEDP) (10 +/- 4 mm Hg [p less than 0.01] and 11 +/- 4 mm Hg [p less than 0.05], respectively, vs 13 +/- 5 mm Hg) and pulmonary capillary wedge pressure (10 +/- 4 mm Hg [p less than 0.01] and 12 +/- 5 mm Hg [p less than 0.05], respectively, vs 14 +/- 6 mm Hg) to the same degree as DB alone. The DB/DA-equal or DB-dominant combination did not induce tachycardia (heart rate, 105 +/- 11 [p less than 0.05] and 95 +/- 14 beats per minute, respectively, vs 90 +/- 17 beats per minute) or have any effect on the right ventricular end-diastolic volume index (RVEDVI) (115 +/- 30 ml/m2 and 117 +/- 33 ml/m2, respectively, vs 127 +/- 42 ml/m2). Moreover, the diastolic parameters of the right ventricle (the ratio of RVEDVI/RVEDP: 15 +/- 8 [p less than 0.05] and 13 +/- 7, ml/mm Hg/m2, respectively, 11 +/- 5 ml/mm Hg/m2) decreased as the ratio of DA increased. This change in the diastolic properties of the right ventricle might have been caused by release of norepinephrine in the myocardium by DA or by improved coronary perfusion with DB. The DB/DA-equal and DB-dominant combinations were superior to DB or DA alone and to the DA-dominant combination in obtaining enhanced right ventricular performance.

Improved outcome based on fluid management in critically ill patients requiring pulmonary artery catheterization

We performed a randomized, prospective trial to evaluate whether fluid management that emphasized diuresis and fluid restriction in patients with pulmonary edema could affect the development or resolution of extravascular lung water (EVLW), as well as time on mechanical ventilation and time in the intensive care unit (ICU), in critically ill patients requiring pulmonary artery catheterization (PAC). PAC was performed on 101 patients. A total of 52 patients were randomized to an EVLW management group using a protocol based on bedside indicator-dilution measurements of EVLW. The other 49 patients were randomized to a wedge pressure (WP) management group in whom fluid management decisions were guided by WP measurements. A total of 89 patients had pulmonary edema (defined as EVLW greater than 7 ml/kg ideal body weight). Except for a clinically unimportant difference in mean age, the two groups were entirely comparable at baseline. The study groups were managed differently, as evidenced by cumulative input-output of 2,239 +/- 3,695 ml (median = 1,600 ml) in the WP group versus 142 +/- 3,632 ml (median = 754 ml) in the EVLW group (p = 0.001). EVLW decreased significantly, and ventilator-days and ICU days were significantly shorter only in patients from the EVLW group. No clinically significant adverse effect occurred as a result of following the EVLW group algorithm. Thus, a lower positive fluid balance, especially in patients with pulmonary edema regardless of cause, is associated with reduced EVLW, ventilator-days, and ICU days.

Effect of dopamine vs norepinephrine on hemodynamics in septic shock. Emphasis on right ventricular performance

The effects of continuously infused dopamine and norepinephrine on hemodynamics, oxygen metabolism, and right ventricular (RV) performance were studied by crossover design in ten patients with septic shock who needed treatment with vasoactive drugs after fluid replacement. Standard hemodynamic measurements were obtained and RV performance assessed before and 1 h after the start of the infusion. All but one patient had pulmonary hypertension, and in seven the RV ejection fraction (RVEF) was lower than 50 percent at baseline. Drugs were titrated to a systolic arterial blood pressure of mean 106 +/- 18 mm Hg for dopamine and 116 +/- 20 mm Hg for norepinephrine (NS). Dopamine infusion increased the cardiac index (CI) 16 percent (p less than 0.02), but heart rate and systemic and pulmonary vascular resistances were unchanged. With norepinephrine CI was unchanged, a heart rate decreased 7 percent (p less than 0.05), and systemic and pulmonary vascular resistance increased 35 and 26 percent, respectively (p less than 0.05). With both drugs, RV volumes and RVEF remained unchanged, and systemic oxygen consumption increased equally (by 19 percent for dopamine and 22 percent for norepinephrine, p less than 0.05); systemic oxygen delivery rose by 17 percent during dopamine infusion and was unchanged during norepinephrine infusion. Norepinephrine increased oxygen extraction vs dopamine (p less than 0.05). There were no differences in urinary output. Norepinephrine may improve the RV oxygen supply/demand ratio, but this potentially beneficial effect on RV ejection fraction may be offset by a concomitant increase in pulmonary vascular resistance and RV afterload. Norepinephrine may not adversely affect the peripheral circulation. In short-term treatment of volume-resuscitated, severe septic shock complicated by pulmonary hypertension and impaired RV performance, norepinephrine may be at least as effective as dopamine.

Effects of two inotropic drugs, dopamine and dobutamine, on pulmonary gas exchange in artificially ventilated patients

The inotropic agents, dopamine (DP) and dobutamine (DB), both decrease PaO2, probably by a redistribution of the VA/Q ratio. The aim of this study was to assess the effect of both drugs on the VA/Q ratio, using the multiple inert gas elimination method. Ten artificially ventilated patients (eight males), aged 45-74 years were investigated. Blood gases, cardiac output and concentrations of inert gases were measured before and 30 min after infusion of DB or DP. DP and DB were administered alternatively at a rate of 5 micrograms.k-1 min-1. The decrease in PaO2 was significantly greater with DP (12 +/- 9 torr) than with DB (7 +/- 9 torr) (P less than 0.01). Both drugs similarly increased cardiac output: +2.61.min-1 +/- 1.4 for DP and 2.21.min-1 +/- 1.5 for DB. Both DP and DB significantly (P less than 0.01) increased the perfusion of alveoli with VA/Q = 0 (+4 +/- 7% for DP and +3 +/- 7% for DB) and 0 less than VA/Q less than 0.1 (+11 +/- 8.5% for DP and +5.5 +/- 10.5% for DB) (no significant difference between the drugs). When shunt and "shunt-like" effect are considered together, there was a significantly greater increase in the amount of blood going to alveoli with a low VA/Q ratio with DP compared to DB. Both drugs decreased the perfusion of alveoli with 0.1 less than VA/Q less than 10, but the decrease was significantly less for DB than for DP (-15 +/- 6.5% for DP and -8.5 +/- 7% for DB, p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of dobutamine on lung microvascular fluid flux in sheep with "sepsis syndrome"

The effect on pulmonary fluid balance of adrenergic receptor agonist agents commonly employed in clinical sepsis has not been well characterized. Therefore, we tested the hypothesis that dobutamine would increase pulmonary microvasular fluid flux in experimental sepsis-induced lung injury. To define the effects of this synthetic catecholamine on pulmonary lymph flow (QL), we infused dobutamine in sheep at two doses in sequence (5 micrograms/kg/min and 10 micrograms/kg/min) before and after the induction of intraperitoneal sepsis which resulted in the development of lung microvascular injury. In the nonseptic state, cardiac output increased at both 5 micrograms/kg/min and 10 micrograms/kg/min (22 and 36 percent, respectively), while QL was unchanged from baseline (for 5 micrograms, delta QL = +0.44 +/- 1.35 ml/15 min; not significant) (for 10 micrograms, delta QL = -0.20 +/- 1.0 ml/15 min; not significant). Values for the ratio of lymph/plasma total protein levels [( L/P]TP) fell modestly in the nonseptic study at both doses (p less than 0.05). With established sepsis syndrome, QL increased from the nonseptic baseline study (2.99 +/- 1.8 to 7.01 +/- 3.95 ml/15 min; p less than 0.05), without change in [L/P]TP ratios or the calculated microvascular hydrostatic pressure. (Pmv) During sepsis, dobutamine infusion was again associated with an increase in cardiac output at both the 5 micrograms/kg/min (+29 percent) and 10 micrograms/kg/min (+33 percent) doses, while QL increased modestly only with the lower dose of dobutamine infused (5 micrograms/kg/min, delta QL = 1.80 +/- 2.2 ml/15 min; p less than 0.05). In this model of sepsis-induced lung injury, dobutamine increased systemic flow without substantially augmenting QL.