Conclusions
Patients in shock, if they survive the initial insult, are
still at risk of dying on a subacute basis from continuing global hypoperfusion and the resultant multiple
organ dysfunction, if they are inadequately resuscitated. Therefore, it is important that rapid, full resuscitation be provided to the patient in shock, to optimize chances of survival and recovery. It is clear that
adequate resuscitation goes beyond the restoration of
a normal blood pressure and urine output. A minimal MAP of 60 mmHg, however, appears to represent a necessary, if not sufficient, condition for survival, which should be maintained before other
resuscitative end points are pursued. After this minimally acceptable blood pressure is assured, more accurate discriminators of adequate perfusion should
be monitored, parameters that reflect correction of
the body’s oxygen debt.
Supranormal DO2 and VO2 as end points of
resuscitation have proved controversial. Those studies that support their use do so by very early use of the
“hemodynamic push.” Yet, many cannot believe that
these parameters should be pushed to the same level
in every patient; that the elderly cardiac patient in
shock should require the same DO2 and cardiac output as the youthful trauma victim. Regardless, a common theme that has emerged from this analysis is the
use of DO2 and VO2, if not as ends, at least as means
to effective resuscitation. With little variance, every
prospective, goal-directed human study that has
shown survival advantage, regardless of the end point
monitored, has used supraphysiologic fluid and inotrope resuscitation techniques championed by Shoemaker and colleagues2 as the means of resuscitation.
Currently, the preponderance of supporting literature favors blood lactate as the optimal resuscitative end point. Because its measurement does not
require specialized or invasive equipment, and because today’s technology provides rapid assay results,
it possesses many advantages in addition to its validated accuracy. Other techniques that indirectly reflect BL, such as BD, gastric mucosal pH, and venous
hypercarbia, may in time prove as useful as BL, because they may correct more rapidly to adequate resuscitation than BL (less lag time). Tissue oxygen
monitoring also holds promise as an emerging technique to gauge resuscitation adequacy. Further prospective goal-directed human studies in all these latter modalities should be encouraged.