Evidence suggests that septic shock patients with chronic arterial hypertension may benefit from resuscitation targeted to achieve higher blood pressure values than other patients, possibly as a result of altered renal autoregulation. The effects of different vasopressor agents on renal autoregulation may be important in this context. We investigated the effects of arginine vasopressin (AVP) and norepinephrine (NE) on renal autoregulation in ovine septic shock. Sepsis was induced by fecal peritonitis. When shock developed (decrease in mean arterial pressure to <65 mmHg and no fluid responsiveness), animals were randomized to receive NE or AVP in a crossover design. Before the switch to the second vasopressor, the first vasopressor was discontinued for 30 min to ensure complete washout of the first vasopressor. Renal autoregulation was evaluated by recording the change in renal blood flow (RBF) in response to manual, stepwise reductions in renal inflow pressure. In this model, the lower limit of renal autoregulation was not significantly altered 6 h after sepsis induction (59 ± 9 vs. 64 ± 7 mmHg at baseline, <i>P</i> = 0.096). After development of shock, the autoregulatory threshold was lower with AVP than with NE (59 ± 5 vs. 65 ± 7 mmHg, <i>P</i> = 0.010). However, RBF was higher with NE both at the start of autoregulatory measurements (206 ± 58 vs. 170 ± 52 ml/min; <i>P</i> = 0.049) and at the autoregulatory threshold (191 ± 53 vs. 150 ± 47 ml/min; <i>P</i> = 0.008). As vasopressors may have different effects on renal autoregulation, blood pressure management in patients with septic shock should be individualized and take into account drug-specific effects.<b>NEW & NOTEWORTHY</b> Septic shock patients with chronic arterial hypertension may benefit from higher blood pressure targets due to underlying deficits in renal autoregulatory efficiency. The current study is the first to show that the choice of vasopressor agent can differentially affect renal autoregulation. These findings may contribute to more personalized blood pressure management in patients with septic shock.
Vasoplegic syndrome is a common complication after cardiac surgery, with negative impact on patient outcomes and hospital costs. Pathogenesis of vasodilatory phenomenon after cardiac surgery remains a matter of controversy. Loss of vascular tone can be partly explained by the depletion of neurohypophyseal arginine vasopressin stores. Vasopressin is commonly used as an adjunct to catecholamines to support blood pressure in refractory septic shock, but its effect on vasoplegic shock is unknown. We hypothesized that the use of vasopressin would be more effective on treatment of shock after cardiac surgery than norepinephrine, decreasing the composite endpoint of mortality and severe morbidity.
This observational study suggests that dopamine administration may be associated with increased mortality rates in shock. There is a need for a prospective study comparing dopamine with other catecholamines in the management of circulatory shock.
Hemoglobin solutions are more than mere blood substitutes. Promising effects on oxygen transport and the microcirculation need to be confirmed, and the results of continuing research are eagerly awaited.
