Table 1. Changes in Hemodynamic Variables, Arterial Blood Gas Values, and Plasma Catecholamine Concentrations afer an Intravenous Dose of 1 ml/kg Saline (Control Group), 10 micro gram/kg Clonidine (Clonidine-10 Group), or 5 micro gram/kg Clonidine (Clonidine-5 Group)