Ventilation-perfusion matching, not functional residual capacity, should be used to determine oxygenation with PEEP.

mmPEEP, cm H2OPaw, cm H20Sa05, %Heart rate, beats/mmPressure,mm HgPa02, mm HgPaCO2, mm HgpHHCO3, mEq/LSo2, %[email protected](7810156886113146/7656387.3320851510559111114&752054892112150/75300459411515517682367.352996 confusing and improper, since PEEP in these settings not only increases the effect of shunting but also increases the dead space of a preexisting mismatch; the condition gets worse, not better. “¿ Worsening of V/Q mismatch―is more appropriate and should be borne in mind as an important complication of PEEP, especially in cases with uneven pulmonary pathologies. The pulse oximeter, which is convenient though not ideal, can be useful in bedside manipulation and titration of PEEP under these circumstances when hypoxemia is refractory or deteriorating. Ofcourse, adequate oxygen transport should be the end point.