Circulatory Failure, Hemodynamic Monitoring, and Hemodynamic Support
Septic shock was defined as hypotension (systolic arterial pressure < 90 mm Hg by invasive monitoring) despite apparently adequate fluid resuscitation, along with the presence of perfusion abnormalities including oliguria, lactic acidosis (blood lactate level > 2.5 mmol/L), and acute alteration of mental status. All patients also required mechanical ventilation because of associated respiratory failure (Pao2/fraction of inspired oxygen [Fio2]of < 300) and/or severely depressed mental acuity. On the first day of hemodynamic support, a general severity index (simplified acute physiology score II [SAPS II]) was calculated as described by Le Gall et al.
The monitoring period corresponded to the duration of hemodynamic support, beginning on the first day of hemodynamic support (day 1), and ending on the last day of hemodynamic support (day n). During the study period, all patients underwent daily bedside two-dimensional echocardiography (2D-ECHO). Additionally, a final echocardiographic study was done before discharge from the ICU. Heart rate was obtained from an ECG lead. BP and central venous pressure (CVP) were monitored by indwelling radial artery and internal jugular vein catheters, respectively. canadian healthcare mall
In all patients, blood volume expansion to a CVP > 12 mm Hg as sole therapy did not control circulatory failure. A dopamine infusion, 8 to 20 Mg/kg/min, combined with dobutamine, 5 to 15 Mg/kg/min, was used as the initial vasoactive support. If this failed, the IV infusion was changed to epinephrine, 0.1 to 2 Mg/kg/min. Finally, norepinephrine, 0.1 to 2 Mg/kg/min, was used when arterial systolic pressure remained < 90 mm Hg despite epinephrine infusion. This protocol of hemodynamic support was in accord with the recent guidelines of the French Society of Intensive Care Medicine. During the first days of hemodynamic support, daily volume expansion was often necessary to complete hemodynamic support and maintain CVP > 12 mm Hg and arterial systolic pressure > 90 mm Hg. Throughout the period of monitoring, the amount of fluid used for resuscitation, including colloids and crystalloids, was carefully recorded for each patient.