Effects of Capnometry Monitoring in Post Anesthesia Care Unit

In France, there is actually no recommandation about capnography monitoring in recovery rooms. Nevertheless, some patients are still ventilated in post-anesthesia care units during awakening period. Alveolar hypoventilation could induce moderate hypercapnia, thereby stimulate central ventilatory command. However, this hypoventilation could delay the clearance of anesthetic gases. Capnometry monitoring could influence ventilation applied to these patients. Recovery rooms nurses would perform moderate hyperventilation in response to hign capnometry values. This method could enhance gases elimination, with faster spontaneous breathing recovery and extubation. Length of stay in recovery room could also be shortened. An objective surrogate of ventilation is maximal End Tidal CO2, if there is no alveolo-capillary gradient abnormality (Obesity, Chronic respiratory disease, Cyanogenic heart disease). Thus, this study will compare the percentage of patients who reached a maximum End Tidal CO2 greater than 45mmHg during awakening period in post-anesthesia care unit (PACU) in 2 groups :

• first group ("non-blind group") with capnography monitoring see by the PACU nurses
• second group ("blind group") with capnography monitoring but PACU nurses cannot see the values Other parameters like the time between ventilator's disconnection and the first ventilatory cycle in spontaneous ventilation, the time between ventilator's disconnection and tracheal extubation or laryngeal mask's withdrawal, the minimal SpO2 reached after tracheal extubation or laryngeal mask withdrawal or the length of stay in PACU are also recorded.

Inclusion criteria

• Major patients with given written consent
• General anesthesia, induction with Propofol infusion and Target-Controlled Infusion (TCI) remifentanil, relayed with inhaled sevoflurane and TCI remifentanil
• Upper airway control with naso-orotracheal tube or laryngeal mask
• Ventilated normotherm patients in PACU

Exclusion criteria

• Minor or pregnant patients
• Obesity with Body Mass Index > 40 kg/m²
• Chronic respiratory disease with SpO2<90% in ambiant air
• Cyanogenic heart disease
• Patients under myorelaxant in PACU