TREATING SEPSIS

Stage C: re-establishing the circulation

Volume Resuscitation

Hypotension is caused by myocardial depression, pathological vasodilatation and extravascation of circulating volume due to widespread capillary leak. The initial resuscitative effort is to attempt to correct the absolute and relative hypovolemia by refilling the vascular tree. There is good evidence that early goal directed aggressive volume resuscitation improves outcomes in sepsis (1).

Conventionally clear resuscitation fluids (crystalloids) such as normal saline or Ringer’s lactate are used (hypo-osmolar dextrose based fluids have no role). In this process, very large amounts of fluid may be required due to redistribution to extravascular “3^rd” spaces (which sequester fluid), and the patient may become extremely edematous. Large volume saline resuscitation may be associated with acidemia, due to hyperchloremia (so called “dilutional acidosis”). Lactate cannot safely be given to patients with severely impaired liver function. Acetate buffered fluids (such as Normisol) have not yet gained widespread use.

Fluid Sequestration in Sepsis

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A SERIES OF CARTOONS  ON FLUID RESUSCITATION

The use of high molecular weight (“colloid”) compounds is favored by many, as a means of minimizing resuscitation volume, and for potential positive oncotic effects. The colloid versus crystalloid debate has gone on endlessly for years, and will continue until the latest generation of high molecular weight starches have been evaluated in large clinical trials (2;3) . Unfortunately, the meta-analyses which many claim to demonstrate a lack of efficacy for colloids were poorly constructed, evaluated agents no longer used and lacked both power and proper outcome data. Of the colloids available, dextrans are used rarely (due to the tendency to cause bleeding), albumin has fallen from favor (may worsen outcome), blood and plasma are used only as restorative liquids and gelatins are popular – but not available in the USA. Most intensivists are limited, outside of blood products, to the use of hydroxy-ethyl starch. There are two formulations of this – Hespan, which is diluted in normal saline, and is known to cause coagulation abnormalities, and Hextend, which is formulated in Ringer’s lactate (4;5) . 

As far as which fluids to use: lactated Ringers is a more physiologic mix than normal saline, and colloids will give a greater volume expansion in a shorter time. It doesn’t really matter which isotonic you use, as long as you administer enough. Secondly, there are very few markers of end organ perfusion in sepsis: urinary output is one of them, do not give it away cheaply by administering diuretics or low dose dopamine.

References

(1)   Rivers E, Nguyen B, Havstad S, Ressler J, Muzzin A, Knoblich B et al. Early goal-directed therapy in the treatment of severe sepsis and septic shock. N Engl J Med 2001; 345(19):1368-1377.

(2)   Choi PT, Yip G, Quinonez LG, Cook DJ. Crystalloids vs. colloids in fluid resuscitation: a systematic review. Crit Care Med 1999; 27(1):200-210.

(3)   Lang K, Boldt J, Suttner S, Haisch G. Colloids versus crystalloids and tissue oxygen tension in patients undergoing major abdominal surgery. Anesth Analg 2001; 93(2):405-409.

(4)   Gan TJ, Bennett-Guerrero E, Phillips-Bute B, Wakeling H, Moskowitz DM, Olufolabi Y et al. Hextend, a physiologically balanced plasma expander for large volume use in major surgery: a randomized phase III clinical trial. Hextend Study Group. Anesth Analg 1999; 88(5):992-998.

(5)   Woolf RL, Chapman MV, Mythen MG. Early clinical experience with a newly formulated hydroxyethyl starch-- Hextend. Br J Anaesth 1999; 82(2):299-300.

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