Effects of low tidal volume and low level PEEP mechanical ventilation on respiratory function in the elderly during general anesthesia

Objective To investigate the effects of low tidal volume(VT) and low level PEEP mechanical ventilation on respiratory and circulation functions in elderly patients during general anesthesia.Methods Twenty 65-80 years old patients,ASA class Ⅰ or Ⅱ,undergoing upper abdominal surgery were randomly assigned into two groups with 10 cases each.Low VT and low level PEEP mechanical ventilation were applied to the patients in group A(VT=6 ml/kg,f=15,PEEP=5 cm H2O),while traditional ventilation was used in group B(VT=9 ml/kg,f=12,PEEP=0).Arterial blood samples were taken and PaO2,PaCO2,A-aDO2,MAP and CVP were recorded at the time points of before operation(T1),30 min after tracheal intubation(T2) and 15 min after tracheal extubation(T3).Peak airway pressure(Ppeak) was recorded during operation.Results At T3,PaO2 in group A was higher than that in group B and A-aDO2 in group A was lower than that in group B.There was no significant difference in PaO2,PaCO2,A-aDO2,MAP,CVP and Ppeak at other lowesponding points between the two groups.Conclusion Low VT and low level PEEP mechanical ventilation improves arterial oxygenation and accelerates the recovery of respiratory functions in elderly patients after operation with no depression on hemodynamics.