Pressure Support Ventilation Versus Continuous Positive Air Way Pressure (CPAP) Using I Gelin Adult Patients,

Introduction of Supra glottic airway devices (SAD) has revolutionized the airway management. The first successful supraglottic airway device, the Laryngeal Mask Airway(LMA).The various other SADs include ProSeal LMA, Intubating LMA and i-gel to overcome the limitations of classic Laryngeal Mask Airway( c-LMA) The risk of aspiration with c-LMA is reported tobe around 9% , pleaseboth the c-LMA and PLMA have cuff related complications. High cuff pressure in laryngeal mask airways can cause damage to the mucosae on periglottic and supraglottic structures .

Therefore, to overcome the limitations of Pro Seal Laryngeal Mask Airway (PLMA )a new and cheaper SAD called i-gel was developed. i-gel is a novel and innovative, latex free supraglottic device, made up of medical grade thermoplastic elastomer, which is soft, gel like, transparent The number of manipulations required are more in PLMA than i gel resulting in hemodynamic changes .The i-gel is comparable to PLMA insuring the airway during controlled ventilation. It is better than PLMA in terms of ease of insertion.

Spontaneous breathing is the most popular mode of ventilation with the laryngeal mask airway (LMA), but it provides less effective gas exchange than does positive pressure ventilation (PPV) . The patients receiving sevoflurane anesthesia with unassisted ventilation have a reduced rib cage contribution to ventilation, decreased tidal volume, and respiratory rate .

Pressure support ventilation (PSV) is a ventilator mode that is initiated by the patient and synchronized with the patient's respiratory effort. And may improve gaseous exchange in patients. In the intensive care unit, it is often considered the preferred mode for weaning mechanical ventilation .PSV provides more effective gas exchange than does unassisted ventilation with CPAP during anesthesia with the LMA while preserving hemodynamic homeostasis.

The use of PSV versus CPAP with the Pro Seal laryngeal mask airway in anesthetized pediatric patients revealed that PSV improved gaseous exchange and reduced work of breathing during general anesthesia PSV via Pro- Seal laryngeal mask airway improves gaseous exchange and ventilation in pediatric patients under general anesthesia more than spontaneous ventilation .

Patients and Methods This prospective,cross over study will be conducted after obtaining approval from the Institutional Review Board (IRB) of faculty of medicine Mansoura University. A written informed consent will be obtained from all participants and the duration of the study will be 2 - 6 months.

Participants:

38 Adult patients with American Society of Anesthesiologists (ASA) physical status (I - II )of both sexes aged (18-65) years scheduled for minor surgery at Urology and Nephrology centre (UNC) will be included in this study.

The Patients with a body mass index (BMI) \>40 or having obstructive air way disease will be excluded.

All patients will be assessed on the day before surgery by detailed history thorough clinical examination, and basal laboratory investigations \[Complete blood count (CBC), Coagulation profile (prothrombin time and INR), liver and renal function tests (liver enzymes, bilirubin, albumin and s. creatinine\], electrocardiograph (ECG) and echo cardiography when needed.

Anaesthesia Induction of anaesthesia with fentanyl 0.5µg/kg - propofol 1mg/kg prior for insertion of device,primary success rate will be recorded.

Maintenance of anaesthesia by sevoflurane inhalation with minimal alveolar concentration (MAC) 2%.

All patients will breath spontaneously from ventilators (Dragers - Primal - germany).

All patients will breath at the first 15 minutes with PSV:triggered by minute volume \<3 liter,with no frequency then the following 15 minutes ventilation will be changed to CPAP mode at 10 cm H2o .

Monitoring: (basal\& every 3minutes)

1. Tidal volume (inspiratory \& expiratory).
2. End tidal co2.
3. Mean air way pressure.
4. Leakage %.
5. Respiratory rate .
6. Spo2.
7. Heart rate.
8. Blood pressure (mean arterial pressure). Adverse effects;Laryngeal spasm.Blood stained device. .

Eligibility Criteria:
Inclusion Criteria:

* Adult patients with (ASA) physical status I - II years scheduled for minor surgery at Urology and Nephrology centre (UNC) will be included in this study.

Exclusion Criteria:

* The Patients with a body mass index (BMI) \>40 or having obstructive air way disease will be excluded.•