The effect of hypoxemic resuscitation from hemorrhagic shock on blood pressure restoration and on oxidative and inflammatory responses.

OBJECTIVE

We investigated whether hypoxemic resuscitation from hemorrhagic shock prevents the late circulatory instability and attenuates the oxidative and inflammatory responses associated with the standard strategy.

METHODS

Prospective, randomized, controlled animal study in an experimental laboratory of a university intensive care unit.

METHODS

Thirty-one New Zealand white rabbits weighting 3.1-3.4 kg

METHODS

Anesthetized animals were subjected to hemorrhagic shock by exsanguinations to a mean arterial pressure of 40 mmHg for 60 min. Resuscitation was performed by reinfusing the shed blood for 30 min under normoxemia (PaO(2) 95-105 mmHg, control group, n=10) or hypoxemia (PaO(2) 35-40 mmHg, hypox-res group, n=10); Ringer's lactate was given from 30 to 60 min to restore arterial pressure within baseline values. A sham group was assigned (n=11). Animals were recorded for 120 min postresuscitation and for further 360 min to assess the early mortality rate.

RESULTS

Hypoxemic resuscitation compared with normoxemic resuscitation from hemorrhagic shock was associated with (a) a better hemodynamic condition assessed by the gradual restoration of blood pressure, higher urinary output associated with less fluid infusion; (b) lower reactive oxygen species production assessed by the reduced blood geometric mean fluorescence intensity, lower malondialdehyde, and higher ratio of reduced to total glutathione levels; (c) attenuation in the plasma concentrations of IL-1beta, TNF-alpha, and IL-6; and (d) no difference in mortality rate.

CONCLUSIONS

Hypoxemic resuscitation from hemorrhagic shock is more efficient than normoxemic in restoring the blood pressure and in attenuating the excessive oxidative and inflammatory responses observed during normoxemic resuscitation.