الفهرس 
Anatomical considerationOnly 14 pages are availabe for public view
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Abstract
General anesthesia impairs pulmonary gas exchange and mild desaturation of arterial blood occurred in 53% of all patients undergoing elective surgery and not monitored routinely by pulse oxymetry. Some of these patients suffered from severe hypoxemia. Thus, it seems reasonable to use high inspiratory oxygen concentration during general anesthesia in order to minimize the risk of hypoxemia if pulse oxymetry is not available. However, atelectasis has been proposed as a major cause of impaired oxygenation during general anesthesia, and atelectasis is promoted by high inspiratory oxygen concentration during induction and maintenance of anesthesia.
Increasing the inspired oxygen fraction during general anesthesia might therefore increase the margin of safety only at the cost of aggravating one cause of hypoxemia. Inspiratory pressure of approximately 40 cm H2O are required to fully re-expand healthy but collapsed alveoli. However, without PEEP these re-expanded alveoli tend to collapse again. A positive end-expiratory pressure of 10 cm H2O has been shown to reduce, but not to eliminate, the amount of atelectasis during general anesthesia, but PEEP per se did not improve oxygenation. This PEEP alone may not be ideal tool for improving gas exchange during general anesthesia.
Summary 91
This study had been done to compare the effect of PEEP versus the effect of PEEP with recruitment maneuver during general anesthesia in improving the arterial oxygenation and lung compliance.
Our study includes 90 patients assigned randomly into one of the three equal sized groups.
Group I: Patients will continue with the same ventilator settings as during the control period and no PEEP will be given (Control group).
Group II: After the control period of 30 min, PEEP equal to 5cm H2O will be added to the ventilator circuit.
Group III: After the control period of 30 min, PEEP equal to 5cm H2O will be added and recruitment will be done.
We found that the PaO2 decreased significantly in the control group relative to its baseline values. In the other two groups, there was significant difference from baseline values both 5 min. and 30 min. after the maneuver, also O2 tension shows significant difference (higher) in the recruitment group relative to PEEP group 30 min. after the maneuver.
Static lung compliance decreased gradually in the control group to become significantly less than baseline and the other two groups. In the PEEP group Static lung compliance remained relatively similar to its baseline 5 min. after the maneuver but 30 min. after the maneuver static lung compliance become significantly different from the baseline values .In the recruitment
Summary 92
group, static lung compliance remained relatively constant 5 min. after the maneuver but 30 min. after the maneuver it becomes significantly higher than the baseline values and the other two groups.
In summary, addition of PEEP to the ventilator circuit during routine anesthesia conduct would reverse anesthesia-induced atelectasis and improve arterial oxygenation and lung compliance; moreover, addition of recruitment maneuver (sustained increase in airway pressure with goal to open collapsed lung tissue) during general anesthesia would further improve arterial oxygenation and lung compliance.
This recruitment maneuver was easy to perform and showed no complications in this small number of patients with healthy lungs.
Further studies are needed to address the post operative benefits and possible side effects of the recruitment maneuver