Clinical trial NCT03802643: Preoxygenation Before General Anesthesia
Official title: Assessment of Oxygenation Values Before General Anesthesia in Elective Surgery
Study type: OBSERVATIONAL
Overall status: UNKNOWN
Conditions: Anesthesia
Preoxygenation
Keywords: Oximetry
Desaturation of Blood
Postoperative pulmonary complications
Lead sponsor: University of Parma
Sponsor class: OTHER
First posted: 2019-01-14
Enrollment: 1000
Sex: ALL
Minimum age (years): 18
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: no
Observational model: COHORT
Time perspective: PROSPECTIVE
Sampling method: NON_PROBABILITY_SAMPLE
Study population: Non-critically ill patients (with no high risk of desaturation) undergoing general anesthesia before elective surgery.

Brief summary: Rationale of the study: we aim to clarify the question (related to still unclear and not univocal response) about the protective or unnecessary role of preoxygenation in non-critically ill patients (otherwise with no high risk of desaturation) undergoing general anesthesia before elective surgery.

It will be also necessary differentiate the development of postoperative complications (pulmonary, cardiovascular, neurological, surgical) due to preoxygenation from the ones related with patient comorbidity, intraoperative and surgical causes, tube disconnection.

Procedure: patient's informed consent signature for adhesion at the study will be initially requested. With their acceptance, parameters will be recorded anonymously in the Case Report Form, identified by their initials and an alphanumeric code, until hospital discharge.

The parameters analyzed will be related to:

* preoperative evaluation; about anamnesis, health general conditions, blood oxygen saturation (Sat02), Metabolic Equivalent of Task (METs)
* intraoperative evaluation; about oxygenations values, recorded before/during induction and maintenance of general anesthesia
* postoperative evaluation; about postoperative complications, pulmonary primarily, and secondary cardiovascular, neurological and surgical, based on the medical record.

The data wil be transferred on Excel worksheet, utilized for descriptive analysis related at every variable. By multivariate logistic regression will be evaluated the major factors influencing postoperative pulmonary complications (PPCs) onset in patients undergoing preoxygenation for elective surgery

Detailed description: Background of the study:

Preoxygenation is a widely used technique that improves the safety of endotracheal intubation. The procedure is carried out by supplying 100% oxygen (FiO2 of 1.0) before the induction of general anesthesia until both end-tidal oxygen (EtO2)\>90% and end-tidal N2 (EtN2)\<5% are reached. Both these markers define the efficacy of the procedure. As a result, the lung oxygen content is increased far beyond normal oxygen consumption by saturating the functional residual capacity with 100% oxygen. This allows for a longer safe apnea time (i.e. the time required for oxyhemoglobin saturation to drop below 90%). The rate at which oxyhemoglobin saturation drops during apnea indicates the efficiency of the maneuver.

This procedure is strongly recommended for all patients undergoing general anesthesia since it lengthens safe laryngoscopy time and grants a wider timeframe to respond to a "cannot intubate/cannot oxygenate" (CICO) scenario, a rare yet life threatening situation. It remains unclear whether this should be considered mandatory for non-critically ill and non-obese patients since their oxygen reserves should suffice for the time required to perform endotracheal intubation or regain spontaneous breathing in the event of a CICO scenario. Nonetheless, the guidelines for the management of endotracheal intubation, proposed by the Difficult Airway Society in 2015 United Kingdom state how it is pivotal to preoxygenate every patient before attempting to intubate. Several methods of preoxygenation have been validated and compared according to duration of safe apnea time, duration of the procedure, success rate (defined as "avoiding manual re-ventilation"), and patient tolerance. The choice between these techniques is based on patient characteristics (age, sex, Body Mass Index, American Society of Anesthesiologist score, Cormack-Lehane grade and Glasgow Coma Scale), settings (e.g., operating room, Intensive Care Unit, emergency situations), equipment, and anesthesiologist's preferences. The two standard approaches are six deep breaths in 1 min and tidal volume breathing for three to 5 min, both at 100% inspired oxygen via a face mask.

The main side effect of preoxygenation is absorption atelectasis that occurs when delivering 100% inspired oxygen. This can be avoided using a lower inspired oxygen concentration (90%), positive pressure techniques, and/or recruitment maneuvers post-endotracheal intubation. Due to the short duration of the procedure, the production of reactive oxygen species and cardiovascular responses are minimal and should not prevent routine preoxygenation.

Eligibility criteria: Inclusion Criteria:

* informed consent signature
* eligible for preoxygenation before general anesthesia, in elective surgery
* age \> 18 years
* surgery duration \> 30 min

Exclusion Criteria:

* emergency/urgent surgery
* severe respiratory disease: Chronic Obstructive Pulmonary Disease stages III-IV, pulmonary fibrosis, documented bullous emphysema, severe emphysema, pneumothorax
* uncontrolled asthma
* severe cardiac disease: Heart Failure stages III-IV (New York Heart Association), coronary artery disease stages III-IV (Canadian Cardiovascular Society)
* previous thoracic surgery
* pregnancy (excluded by anamnesis or laboratory test)
* informed consent refusal

Primary outcomes:
measure: Evaluation of preoxygenation use in elective surgery, reporting oxygenations values
timeFrame: From before induction of general anesthesia until the end of surgical procedure, up to 10 hours
measure: Incidence of postoperative pulmonary complications (PPC) related to preoxygenation
timeFrame: From immediately after surgery until hospital discharge, up to 26 weeks
Secondary outcomes:
measure: Incidence of intraoperative desaturation/hypoxia
timeFrame: From achieved endotracheal intubation until the end of surgical procedure, up to 10 hours
measure: Incidence of cardiovascular postoperative complications
timeFrame: From immediately after surgery until hospital discharge, up to 26 weeks
measure: Incidence of neurological postoperative complications
timeFrame: From immediately after surgery until hospital discharge, up to 26 weeks
measure: Incidence of surgical postoperative complications
timeFrame: From immediately after surgery until hospital discharge, up to 26 weeks
measure: Incidence of Intensive Care Unit admission and its duration
timeFrame: From immediately after surgery until hospital discharge, up to 26 weeks
measure: Incidence of length of in-hospital stay
timeFrame: From immediately after surgery until hospital discharge, up to 26 weeks
Other outcomes:
Locations:
city: Parma
country: Italy
facility: Azienda Ospedaliero-Universitaria di Parma
Study officials:
affiliation: Azienda Ospedaliero-Universitaria di Parma
name: Michela Tosi, MD
role: PRINCIPAL_INVESTIGATOR
affiliation: University of Parma
name: Benedetta Siroli, MD
role: PRINCIPAL_INVESTIGATOR
affiliation: University of Parma
name: Samantha Gorgoglione, MD
role: PRINCIPAL_INVESTIGATOR
affiliation: University of Parma
name: Valentina Bellini, MD
role: PRINCIPAL_INVESTIGATOR
affiliation: University of Parma
name: Leonardo Fortunati, MD
role: PRINCIPAL_INVESTIGATOR
affiliation: University of Parma
name: Andrea Parodi, MD
role: PRINCIPAL_INVESTIGATOR
affiliation: University of Parma
name: Andrea Briolini, MD
role: PRINCIPAL_INVESTIGATOR
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