Alveolar Recruitment Maneuver During Cesarean Section Improves Lung Compliance (CSRecGHPyr)

The investigators tested the hypothesis that alveolar recruitment maneuver during cesarean section and in women under general anesthesia improves lung compliance and gas exchange. The investigators applied recruitment maneuver and positive end expiratory pressure (PEEP) 8 cmH2O. The maximum alveolar pressure limit (Ppeak)was 45 cmH2O during the recruitment maneuver. The primary end point of the study is the improvement of the lung compliance measured as volume difference/pressure difference (dv/dp) or ml/cmH2O

The investigators used recruitment maneuver during cesarean section and in women under general anesthesia. The primary end point of the study is the improvement of the lung compliance measured as volume difference/pressure difference (dv/dp) or ml/cmH2O after the recruitment maneuver. The investigators used 2 groups of patients. In the first group the investigators used pressure control ventilation for the recruitment maneuver. After the ventilator was switched to pressure control mode the investigators increased the inspiratory time to 50% and the inspiratory pressure above Positive End Expiratory Pressure (Ppeak) to 20 cmH2O. Then the investigators progressively increased Positive End Expiratory Pressure (PEEP) to have a peak inspiratory pressure (Ppeak) to 45 cm H2O. The whole recruitment maneuver lasts 2 minutes. After the recruitment maneuver the investigators used volume control ventilation again (with the baseline settings)and PEEP step wised decreased to 8 cmH20but. PEEP (8cmH2O) was left until the end of the operation. In the second group the investigators did not used lung recruitment maneuver at all. In both groups lung compliance was measured (dynamic and static)as dv/dp (ml/cmH2O). Measures were assessed 1 minute after delivery (but before recruitment), 3 minutes after recruitment (first group) at 10 and at 20 minutes after recruitment. The investigators also measured Ppeak (cmH2O) and Pplateau (cmH2O)inspiratory pressures , blood pressure (mmHG), beats per minute, oxygen saturation, end-tidal CO2 according to the above time frame, blood Gases before and 3 minutes after recruitment etc.

The investigators used alveolar recruitment maneuver by increasing inspiratory pressure to 20 cmH20 and progressively increasing Positive Expiratory Pressure (PEEP) up to 45 cmH2O maximal (Ppeak) inspiratory pressure. The recruitment maneuver lasted 2 minutes. In this group PEEP was set to 8 cmH2O, after the recruitment maneuver, and was left until the end of the operation.

In this group and during recruitment maneuver the investigators used pressure control ventilation and increased inspiratory time to 50%. The investigators used alveolar recruitment maneuver by increasing inspiratory pressure to 20 cmH20 and progressively increasing Positive Expiratory Pressure (PEEP) up to 45 cmH2O maximal (Ppeak) inspiratory pressure. The recruitment maneuver lasted 2 minutes. After the maneuver PEEP was set to 8 cmH2O and was left until the end of the operation. After the end of the recruitment maneuver volume control ventilation was used until the end of the operation too.

Lung Compliance change measured as volume difference/pressure difference (dv/dp) or ml/cmH2O is being assessed

Before recruitment, 3 minutes after recruitment, 10 minutes after recruitment and 20 minutes after recruitment

Inclusion Criteria: general anesthesia, hemodynamically stable Exclusion Criteria: intracranial hypertension, pulmonary hypertension, low blood pressure (MBP<80 mmHg), Heart rate > 100 beats/min, patient refusal

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