cardiovascular-agents and dopexamine

The optimal sympathomimetic drug to support blood pressure without adverse vasoconstriction of free flap circulation remains unknown. This study examined the effects of four agents (epinephrine, norepinephrine, dobutamine, and dopexamine) on free flaps following resection of head and neck cancer.. Twenty-four patients (25 data sets) were recruited into the study. Each patient received an infusion of the four drugs in a random order, with an intervening washout period between drugs, at four infusion rates. Continuous free flap skin blood flow monitoring was performed using laser Doppler velocimetry, with a second sensor on normal skin acting as a control. Global cardiovascular variables were monitored using the LiDCO Rapid Pulse Contour Analysis System (LiDCO Ltd., Cambridge, United Kingdom).. Dose-dependent, increased free flap skin blood flow was observed with norepinephrine and dobutamine. Both dopexamine and epinephrine infusions decreased blood flow. Flap skin blood conductance decreased (vasoconstriction) with norepinephrine, but markedly less than in control tissue, so overall the flap skin blood flow increased with increasing arterial blood pressure. Dobutamine increased flap skin conductance, without significantly increasing blood pressure, and modestly increased flap blood flow.. Both dobutamine and norepinephrine had beneficial effects on flap skin blood flow. The maximal improvement in flow occurred with norepinephrine, making it the optimal pressor to use in patients with hypotension after free flap surgery.

Topics: Adult; Aged; Cardiovascular Agents; Dobutamine; Dopamine; Dose-Response Relationship, Drug; Epinephrine; Free Tissue Flaps; Head and Neck Neoplasms; Humans; Microcirculation; Middle Aged; Norepinephrine; Regional Blood Flow; Skin; Skin Transplantation; Sympathomimetics

Gastric mucosal-arterial PCO2 gradient (P(g-a)CO2) is used to assess splanchnic perfusion and oxygenation. We evaluated whether P(g-a)CO2 reflects whole body (Q) and splanchnic (Qsp) blood flow, oxygen delivery (DO2) and consumption (VO2) after coronary artery by pass graft (CABG) operation. Thirty patients received dobutamine or dopexamine to increase cardiac index, 15 patients enalapril or sodium nitroprusside to lower blood pressure, and 30 patients were controls. We measured Q, Qsp (hepatic vein catheter and indocyanine green), and gastric mucosal PCO2 (nasogastric tonometer) before and after interventions. Multiple linear regression model showed that none of the changes in Q, Qsp, and splanchnic or systemic DO2 and VO2 significantly explained changes in P(g-a)CO2 (deltaP(g-a)CO2). All independent variables together explained only 7% of deltaP(g-a)CO2. Increased splanchnic blood flow (0.65 +/- .19 vs. 0.94 +/- .31 L/min/m2, P < 0.001) and increased splanchnic DO2 (101 +/- 28 vs. 143 +/- 42 mL/min/m2, P < 0.001) during catecholamine infusions were associated with increased P(g-a)CO2 (8 +/- 8 vs. 11 +/- 7 mmHg, P = 0.003). P(g-a)CO2 does not reflect whole body or splanchnic blood flow, DO2 or VO2 after CABG operations. The physiology of P(g-a)CO2 is complex and therefore it is difficult for clinicians to interpret changes in gastric mucosal-arterial PCO2 gradient in individual patients after cardiac surgery.

Topics: Antihypertensive Agents; Arteries; Carbon Dioxide; Cardiovascular Agents; Catecholamines; Coronary Artery Bypass; Dobutamine; Dopamine; Enalapril; Gastric Mucosa; Hemodynamics; Histamine H2 Antagonists; Humans; Hydrogen-Ion Concentration; Hypertension; Nitroprusside; Oxygen; Oxygen Consumption; Partial Pressure; Postoperative Period; Splanchnic Circulation; Vasodilator Agents