PERSISTENT OLIGURIA AND HYPOTENSION

Clinically significant hypotension (mean arterial pressure, MAP < 65 mmHg) must be correlated with UOP and other indicators of resuscitation adequacy. Adequate end-organ perfusion as estimated by UOP 30-50 mL/hr generally requires a MAP > 65 mm Hg. Persistent oliguria and hypotension should trigger an assessment of the patient’s hemodynamic status and intravascular volume. Reassess for a possible missed injury or ongoing bleeding. Monitor intravascular fluid status using all available technologies. Consider early use of a colloid as discussed above as an adjunct.

If hypotension persists, use vasopressin 0.04 units/min (do not titrate) followed by norepinephrine (titrate 2-20 mcg/min) if needed. Epinephrine may be used as an additional vasopressor in severe shock proven to be non-hemorrhagic.

If intravascular volume appears adequate, STOP increasing IV fluid rate even if oliguria persists. Consider this patient hemodynamically optimized and that the oliguria likely results from an established renal insult. Expect and tolerate some degree of renal dysfunction in large burns. Continued increases in IV fluid administration, despite optimal hemodynamic parameters, will only result in “resuscitation morbidity,” which is often more detrimental than kidney injury.

If the patient exhibits catecholamine (vasopressor)-resistant shock, consider the following diagnoses:

- Missed injury and/or on-going blood loss.
- If pH < 7.20, adjust ventilator settings to target PCO2 30-35 mmHg. If, despite optimal ventilation, patient still has a pH < 7.2, consider administration of sodium bicarbonate.
- Adrenal insufficiency.6
- Consider empirically administering calcium chloride (8-16 mg/kg IV) for refractory hypotension, especially in patients who have received a blood transfusion. If able to measure levels, maintain ionized calcium >/= 1.2 mmol/L.