Objective: To study the effects of norepinephrine on right ventricular function in patients with hyperdynamic septic shock.
Design: Prospective, open study.
Setting: A 15 bed ICU in a university hospital.
Patients: 9 patients with hyperdynamic septic shock (SBP < 90 mmHg, Cl > or = 4 l.min-1.m-2, SVRI < or = 850 dynes.s.cm-5m-2 and oliguria).
Interventions: Plasma volume expansion was used to correct a suspected volume deficit and then, norepinephrine infusion was started and titrated to restore systemic blood pressure to the normal range (mean infusion rate: 1.1 +/- 0.2 mcg.kg-1.min-1). Norepinephrine was the only vasoactive agent used in these patients.
Measurements and results: A modified Swan-Ganz catheter mounted with a fast response thermistor was inserted in each patient, allowing repeated measurements of RVEDVI and RVEF. At time of inclusion to the study, all but one patient had elevated MPAP (23 +/- 4 mmHg) and RVEF < or = 50%, and all patients had RVEDVI > or = 90 ml.m-2. During norepinephrine infusion, MAP increased from 51 +/- 9 to 89 +/- 10 mmHg (p < 0.0001), PVRI increased from 204 +/- 35 to 286 +/- 63 dynes.s.cm-5.m-2 (p < 0.05), and despite this increase in right ventricular afterload, no detrimental effect in RVEF (36 +/- 11 to 36 +/- 10%) or in RVEDVI (116 +/- 30 to 127 +/- 40 ml.m-2) was observed. A Frank-Starling relationship for the right ventricle was constructed by plotting an index of ventricular performance (RVSWI) against an index of ventricular preload (RVEDVI). A significant upward shift to the right of the relationship was observed during norepinephrine infusion.
Conclusion: It was concluded that norepinephrine exerted a favourable effect on right ventricular function.