Dobutamine in severe scorpion envenomation: effects on standard hemodynamics, right ventricular performance, and tissue oxygenation.

OBJECTIVES

To document the effects of dobutamine on standard hemodynamics and right ventricular (RV) performance in patients exhibiting pulmonary edema following severe scorpion envenomation, and to characterize the tissue oxygenation profile in patients sustaining scorpion envenomation-related shock.

DESIGN

Prospective cohort study.

SETTING

An ICU in a university hospital.

PATIENTS

Nineteen consecutive patients were admitted to the ICU for severe scorpion envenomation; all 19 patients exhibited hemodynamic pulmonary edema, and 10 patients had peripheral shock.

INTERVENTIONS

All patients underwent a hemodynamic study with a Swan-Ganz catheter. In 8 of 19 patients, the thermodilution catheter was equipped with a fast-response thermistor.

MEASUREMENTS AND RESULTS

Standard hemodynamic parameters were recorded on admission and following the infusion of dobutamine in all patients at a dosage, from 7 to 20 microg/kg/min, intended to achieve the best hemodynamic and tissue oxygenation compromise. RV ejection fraction (RVEF) and RV volumes were simultaneously recorded in 8 patients, and tissue oxygenation parameters were assessed in the 10 patients with peripheral shock. The clinical signs of tissue hypoperfusion improved, and optimal hemodynamic parameters were achieved at a mean +/- SD dobutamine dosage of 17 +/- 7 microg/kg/min. Dobutamine infusion evoked statistically significant increases in cardiac index, from 2.3 +/- 0.6 to 3.6 +/- 0.7 L/min/m2; stroke volume index, from 18 +/- 5 to 31 +/- 10 mL/m2; and systemic arterial pressure, from 64 +/- 12 to 78 +/- 14 mm Hg. Pulmonary artery occlusion pressure (PAOP) and venous admixture decreased significantly: from 23 +/- 4 to 15 +/- 6 mm Hg and from 29 +/- 7% to 20 +/- 5%, respectively. With respect to RV function, dobutamine infusion significantly increased the RVEF, from 24 +/- 7% to 42 +/- 9%, without significantly changing the RV end-diastolic volume index, reflecting an enhanced RV contractility. In patients with peripheral circulatory failure, the baseline tissue oxygenation profile was consistent with cardiogenic shock, showing increased oxygen extraction as a consequence of a striking depression in oxygen delivery (DO2). After dobutamine infusion, DO2 improved significantly, from 386 +/- 104 to 676 +/- 156 mL/min/m2, with a significant decrease in oxygen extraction, from 34 +/- 8% to 24 +/- 6%.

CONCLUSIONS

In severe scorpion envenomation, dobutamine infusion improves impaired heart function. The effects involve both left ventricular and RV dysfunction. Impaired tissue oxygenation is also improved.