Vasopressor Use and Acute Renal Failure in Sepsis
Vasopressor Use and Acute Renal Failure in Sepsis
In sepsis patients who require high-dose vasopressors, despite keeping central venous pressure (CVP) in the range of 12-15 mmHg, how do you prevent acute renal failure? High doses of norepinephrine will cause further renal vasoconstriction to add to the renal insult caused by sepsis itself. What additional measures can be taken when oliguria sets in?
Rajesh Kasture, MD (anesthesiology)
This is a very important question because acute renal insufficiency is one of the most commonly encountered problems in patients with septic shock. The cornerstone of therapy in this condition is intravenous fluid resuscitation. As you mentioned, targeting resuscitation to hemodynamic measures may provide more appropriate resuscitation. However, the most useful or accurate endpoints to target during resuscitation remain to be determined. CVP, pulmonary artery occlusion (wedge) pressure (PAOP), and indices of oxygenation such as central venous or mixed venous oxygen have all been considered, but none has proven to be superior. It is important to note that CVP may not accurately reflect left ventricular preload and thus may not be an adequate marker of resuscitation, particularly in the setting of mechanical ventilation or changes in intrathoracic pressure.
In resuscitating patients with sepsis, both colloid and crystalloid solutions are frequently used. While either solution may improve global indices of perfusion (eg, blood pressure), colloids may achieve this endpoint more quickly because of the smaller infusion volume required. For this reason, and the natural physiologic rationale that colloids more closely reflect the plasma constituents being lost, colloids are often chosen for resuscitation of patients in shock. In patients with septic shock, albumin may be the colloid of choice given the relative risk of coagulopathy associated with dextrans and the apparent increased risk of renal failure with starch solutions. However, there is no proven benefit to any colloid over crystalloid solutions, which are less expensive and may produce the same patient outcomes.
Perhaps the most important aspect of resuscitation is the adequacy and timing of fluid administration. These components may play the largest roles in preventing organ dysfunction in septic shock. In general, the standard measures of resuscitation (CVP, arterial pressure, urine output) are imprecise and insensitive to tissue hypoperfusion. Studies have shown that early interventions with targeted resuscitation goals can reduce subsequent illness severity and improve survival from septic shock. It is fair to equate the presentation of septic shock with that of a major traumatic injury, wherein the "golden hour" of medical care needs to be aggressive and precise to maximize the chances of survival. Apart from early and appropriate targeted fluid resuscitation in septic shock, there are no specific therapies for prevention or treatment of acute renal failure.
In sepsis patients who require high-dose vasopressors, despite keeping central venous pressure (CVP) in the range of 12-15 mmHg, how do you prevent acute renal failure? High doses of norepinephrine will cause further renal vasoconstriction to add to the renal insult caused by sepsis itself. What additional measures can be taken when oliguria sets in?
Rajesh Kasture, MD (anesthesiology)
This is a very important question because acute renal insufficiency is one of the most commonly encountered problems in patients with septic shock. The cornerstone of therapy in this condition is intravenous fluid resuscitation. As you mentioned, targeting resuscitation to hemodynamic measures may provide more appropriate resuscitation. However, the most useful or accurate endpoints to target during resuscitation remain to be determined. CVP, pulmonary artery occlusion (wedge) pressure (PAOP), and indices of oxygenation such as central venous or mixed venous oxygen have all been considered, but none has proven to be superior. It is important to note that CVP may not accurately reflect left ventricular preload and thus may not be an adequate marker of resuscitation, particularly in the setting of mechanical ventilation or changes in intrathoracic pressure.
In resuscitating patients with sepsis, both colloid and crystalloid solutions are frequently used. While either solution may improve global indices of perfusion (eg, blood pressure), colloids may achieve this endpoint more quickly because of the smaller infusion volume required. For this reason, and the natural physiologic rationale that colloids more closely reflect the plasma constituents being lost, colloids are often chosen for resuscitation of patients in shock. In patients with septic shock, albumin may be the colloid of choice given the relative risk of coagulopathy associated with dextrans and the apparent increased risk of renal failure with starch solutions. However, there is no proven benefit to any colloid over crystalloid solutions, which are less expensive and may produce the same patient outcomes.
Perhaps the most important aspect of resuscitation is the adequacy and timing of fluid administration. These components may play the largest roles in preventing organ dysfunction in septic shock. In general, the standard measures of resuscitation (CVP, arterial pressure, urine output) are imprecise and insensitive to tissue hypoperfusion. Studies have shown that early interventions with targeted resuscitation goals can reduce subsequent illness severity and improve survival from septic shock. It is fair to equate the presentation of septic shock with that of a major traumatic injury, wherein the "golden hour" of medical care needs to be aggressive and precise to maximize the chances of survival. Apart from early and appropriate targeted fluid resuscitation in septic shock, there are no specific therapies for prevention or treatment of acute renal failure.
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