Informations générales (source: ClinicalTrials.gov)
Effect of the Duration of Pre-oxygenation (3 Minutes vs 6 Minutes) on Apnea Tolerance in Obese Patients (BMI> 30 kg / m2) During the Induction of General Anesthesia (OBE_PreOx)
Interventional
N/A
Fondation Hôpital Saint-Joseph (Voir sur ClinicalTrials)
janvier 2021
décembre 2024
29 juin 2024
The occurrence of arterial oxygen desaturation (hypoxemia) during the induction of
general anesthesia remains one of the main causes of complications and mortality in
anesthesia. In a healthy patient breathing in ambient air [Inspired O2 fraction (FiO2) =
21%] before the onset of narcosis, a drop in arterial O2 saturation (SpO2) occurs within
1 to 2 minutes. When pre-oxygenation is performed for 3 minutes in healthy subjects with
FiO2 = 100%, SpO2 is less than 97% after 7.9 minutes of apnea and arterial O2
desaturation (SpO2 <93%) occurs after 8 to 9 minutes. For this reason and "in order to
prevent arterial desaturation during tracheal intubation or supraglottic device insertion
maneuvers", it is recommended "to systematically perform a pre-oxygenation procedure (3
min / 8 deep breaths) , including in the context of an emergency ". Tolerance to apnea is
conditioned by the amount of O2 stored during the pre-oxygenation phase. Oxygen is
transported to different tissues in 2 forms: combined with hemoglobin (Hb) and in
dissolved form. In ambient air, the quantity of O2 transported by the Hb is much greater
than the part transported in dissolved form. However, when the patient breathes a gas
enriched in O2, all the molecules of Hb are quickly saturated (SpO2 = 100%), while the
content of dissolved O2 increases constituting a reserve allowing to increase the
tolerance to apnea.
Under usual conditions (3 minutes pre-oxygenation with FiO2 = 1), tolerance to apnea is
shorter in obese subjects. Arterial O2 desaturation occurs after 2-3 minutes of apnea in
patients with grade III obesity [Body Mass Index (BMI)> 35 kg / m2]. In addition,
arterial O2 desaturation is faster the higher the BMI is. In fact, in obese patients, the
lung volumes that can be mobilized in the supine position are modified compared to the
non-obese subject: decrease in vital capacity, decrease in expiratory reserve volume,
increase in airway resistance, decrease in thoracic compliance. These changes are, in
part, explained by the weight of tissue on the rib cage and abdomen leading to
compression of the lungs and diaphragm. In addition, there is also an increase in oxygen
consumption in patients with a BMI> 40.
Different techniques have been proposed to increase apnea tolerance in obese patients.
For Dixon et al., The desaturation of the morbidly obese subject (BMI> 40 kg / m2) is
less rapid after 3 minutes of pre-oxygenation carried out with the patient in a
half-seated position at 25 °: 201 seconds against 155 seconds in the Control group. This
additional time seems to correlate with the value of the arterial pressure in O2 (PaO2)
measured at the end of the pre-oxygenation (442 vs 360 mmHg). Likewise, the proclive
position (30 ° reverse Trendelenburg) during the pre-oxygenation phase seems effective in
limiting the occurrence of desaturation after induction.
The O2 reserve is usually assessed by measuring the partial pressure of O2 in the
arterial blood. A value greater than 100 mmHg indicates that an amount of O2 is "in
reserve", increasing tolerance to apnea. In practice, this examination is not feasible in
current practice because it requires the performance of an invasive procedure, cannot be
measured continuously and the rendering of the result is delayed by several minutes. In
recent years, a technology based on spectrophotometry has been developed to measure the
saturation of Hb in O2 in non-pulsatile blood. By algorithmic transformation, an Oxygen
Reserve Index (ORI) is calculated. Its value varies from 0 to 1 and covers a data range
between 100 and 200 mmHg of blood pressure in O2 (moderate hyperoxia). This data is
obtained continuously and non-invasively from a sensor (RD Rainbow SET R Sensors; Masimo)
placed on the 3rd or 4th finger of the hand. When a patient receives an O2 enriched gas
mixture, the value of ORI increases rapidly and reaches a plateau. When the patient is in
apnea, the drop in the ORI value precedes the drop in SpO2 by several tens of seconds. In
a pilot study observing the kinetics of ORI in non-obese (BMI <25 kg / m2) or obese (BMI>
30 kg / m2) anesthetized patients, we observed that the time required to reach the
plateau of l The ORI was longer (133 ± 30 seconds) in "obese" patients compared to
"non-obese" patients (89 ± 28 seconds). Thus, one hypothesis to explain the poorer
tolerance to apnea in obese patients would be that the duration of 3 minutes of
pre-oxygenation as recommended in the recommendations is insufficient.
Etablissements
| Les établissements d'Île-de-France dont les données sont issues de ClinicalTrials.gov Origine et niveau de fiabilité des données | |||||
|---|---|---|---|---|---|
| GH PARIS SITE SAINT JOSEPH | Pascal ALFONSI, MD | Contact (sur clinicalTrials) | |||
Critères
Tous
Inclusion Criteria:
- Patient aged ≥ 18 years
- Patient to have general anesthesia
- Patient affiliated to a health insurance plan
- French-speaking patient
- Patient who has given free, informed and written consent
- Patient aged ≥ 18 years
- Patient to have general anesthesia
- Patient affiliated to a health insurance plan
- French-speaking patient
- Patient who has given free, informed and written consent
- Patient with a BMI between 25 and 30 kg / m2
- Patient with a BMI> 40 kg / m2
- Patient whose O2 stock is insufficient, without this being linked to obesity
- Patient with severe respiratory pathology (COPD stage 3 or 4, severe asthma)
- Patient with active smoking
- Patient with a history of lobectomy or pneumonectomy
- Patient coming for emergency surgery
- Patient with a known allergy to rocuronium or sufentanil or propofol
- Pregnant or breastfeeding women
- Patient under guardianship or curatorship
- Patient deprived of liberty