Fluid Resuscitation in Sepsis

Primary Goals and Physiological Basis

The Surviving Sepsis Campaign guidelines recommend beginning with 30 mL/kg of crystalloid within the first 3 hours to restore tissue perfusion and stabilize hemodynamics in patients with sepsis 1, 2
Fluid administration increases venous return, cardiac preload, and subsequently cardiac output in fluid-responsive patients, enhancing tissue oxygen delivery and potentially reversing tissue hypoxia 1
Sepsis causes vasodilation and increased capillary permeability, leading to relative and absolute hypovolemia, which can be addressed with fluid resuscitation 3
The American College of Cardiology is not mentioned in this article, however, the Surviving Sepsis Campaign guidelines are, and they recommend fluid resuscitation as a crucial step in managing sepsis 1, 2

Initial resuscitation should aim to restore tissue perfusion, with a fixed volume of 30 mL/kg of crystalloid enabling clinicians to initiate resuscitation while obtaining more specific information about the patient's hemodynamic status 1, 2, 4, 5
Further fluid administration should be guided by functional hemodynamic measurements, using dynamic measures rather than static measures to predict fluid responsiveness 1, 2, 4, 5
Target a mean arterial pressure (MAP) of at least 65 mmHg in patients requiring vasopressors, and use clinical markers of improved tissue perfusion, such as normalization of heart rate, improvement in blood pressure, and increased urine output, as endpoints of resuscitation 2, 4, 5, 6

Adequate tissue perfusion should be the principal endpoint of resuscitation, rather than specific volume goals, with clinical markers including normalization of heart rate, improvement in blood pressure, improved mental status, enhanced peripheral perfusion, and increased urine output 6, 3, 4, 5
Excessive fluid administration can lead to pulmonary edema, tissue edema, and abdominal compartment syndrome, highlighting the need for careful monitoring and fluid stewardship 6
Special considerations are necessary for specific patient populations, such as those with heart failure, who may require smaller fluid boluses with earlier initiation of vasopressors, and elderly patients or those with renal impairment, who may be at higher risk for fluid overload 7, 8

The American Society of Anesthesiologists recommends a urine output of 0.5-1 mL/kg/hr as the primary clinical endpoint for assessing adequate fluid resuscitation, supplemented by other markers of tissue perfusion including lactate normalization, MAP ≥65 mmHg, and clinical examination 9
The Society of Critical Care Medicine suggests that urine output remains the easiest and fastest parameter to adjust fluid resuscitation rates in real-time, and this is consistently recommended across burn resuscitation, sepsis management, and general critical care as a key clinical marker 9

The American College of Critical Care Medicine recommends a MAP of ≥65 mmHg as the minimum target during resuscitation to maintain adequate perfusion pressure and preserve autoregulation in critical vascular beds 10
A MAP of 45 mmHg represents severe hypotension requiring immediate intervention with additional fluids and likely vasopressor support, according to the Society of Critical Care Medicine 10

The European Society of Intensive Care Medicine states that lactate is an important marker of tissue perfusion, with normalization indicating improved oxygen delivery, and serial lactate measurements every 2-6 hours are more valuable than a single value to assess the trajectory of resuscitation 11
Lactate should be interpreted alongside other perfusion markers rather than in isolation, as recommended by the European Society of Intensive Care Medicine 11

The Surviving Sepsis Campaign recommends evaluating all of the following together to determine adequate resuscitation: urine output, MAP, lactate, and clinical perfusion markers, as stated in the Intensive Care Medicine journal and the Anaesthesia journal 9, 11

Urine output > 0.5 mL · kg⁻¹ · h⁻¹ is the primary bedside endpoint for confirming adequate fluid resuscitation. This threshold is recommended by the Surviving Sepsis Campaign as the most reliable real‑time marker of sufficient intravascular volume. 12
A urine output of 0.11 mL · kg⁻¹ · h⁻¹ reflects oliguric acute kidney injury and indicates persistent under‑resuscitation. Values this low represent < 25 % of the minimum acceptable output, signifying severe ongoing hypovolemia. 13

Administer 30 mL · kg⁻¹ of isotonic crystalloid within the first 3 hours for patients with evidence of tissue hypoperfusion. This rapid bolus is a core recommendation of the Surviving Sepsis Campaign for early sepsis‑related dehydration. 14

Maintain a mean arterial pressure (MAP) of ≥ 65 mmHg during resuscitation. MAP ≥ 65 mmHg is a guideline‑endorsed target to ensure adequate organ perfusion. 15
Assess additional clinical perfusion markers (e.g., normalized heart rate, improved blood pressure, warm skin with capillary refill < 2 seconds, reduced mottling, and improved mental status) alongside urine output and MAP to confirm restoration of tissue perfusion. 13

Continue fluid administration until all objective perfusion parameters improve, ensuring that the net fluid input exceeds ongoing losses (urine output + insensible losses of ~30–50 mL · h⁻¹ + gastrointestinal losses). This balance prevents persistent hypovolemia. 12

Up to 4 L or more of crystalloid may be required within the first 24 hours to achieve the above endpoints in severely dehydrated patients. The exact volume should be titrated to the individual’s response. 16