[The impact of positive end-expiratory pressure on cerebral perfusion pressure and hemodynamics in patients receiving lung recruitment maneuver].

Objective: To explore the impact of lung recruitment maneuver (RM) on intracranial pressure (ICP), cerebral perfusion pressure (CPP) and mean arterial pressure (MAP).

Methods: RM was performed and ICP, MAP, central venous pressure (CVP), saturation of arterial oxygen (SpO2) were monitored continuously in 6 severe cerebral injury patients combined with lung injury, who were indicated for mechanical ventilation and meeting the criteria for intracranial pressure monitoring. RM included pressure control ventilation with stepwise increase in positive end-expiratory pressure (PEEP).

Results: RM was performed for 22 times in 6 patients, among them two were moribund due to sharp drop of blood pressure and CPP. In the remaining 20 attempts, the mean values of MAP, CVP, ICP, CPP measured at each PEEP level showed no significant difference compared with baseline values (all P>0.05). MAP was significantly correlated with CPP (r=0.706, P=0.000). In the remaining RMs, a correlation between MAP and CPP accounted for 85% (17/20) of total RMs, that between PEEP and CVP accounted for 75% (15/20), that between PEEP and ICP accounted for 75% (15/20), and that between PEEP and CPP existed in 40% (8/20). In a total of 22 cases, there were 6 patterns of response of MAP to alteration in PEEP: MAP maintained relatively stable in 8 case, MAP decreased when PEEP increased and increased when PEEP decreased in 6 case; in 2 cases MAP elevated with increase in PEEP, and drop to baseline with decrease in PEEP, in 2 cases it fell with increase in PEEP but it did not rise with decrease in PEEP, in 2 cases it rose with increase in PEEP but remained at a high level with PEEP decreased to baseline, in 2 cases, MAP dropped abruptly with increase in PEEP resulting in termination of RM. In 11 cases, ICP increased with increase in PEEP and decreased with lowering of PEEP. ICP maintained stable in 6 cases, and ICP maintained at a high level and did not return to baseline after RM in 3 cases. CPP decreased with increase in PEEP and increased when PEEP decreased, and it returned to baseline when PEEP was back to baseline in 12 case. CPP kept constant in 6 case. In 2 cases, CPP remained at a low level, and it returned to baseline 10-20 minutes after PEEP was lowered to baseline.

Conclusion: There is considerable individual difference in impact of RM on MAP, ICP and CPP in patients with cerebral. ICP monitoring is helpful to assure safety of RM in patients with cerebral injury complicated with lung injury.