Preoxygenation With Optiflow™ in Morbidly Obese Patients is Superior to Face Mask

Preoxygenation With Optiflow™, a High Flow Nasal Cannula (HFNC), is Superior to Preoxygenation With Facemask in Morbidly Obese Patients Undergoing General Anesthesia

Optiflow™ may provide an opportunity to prolong apnea time in the morbidly obese patient population. This study will examine whether Optiflow can do this, and compare the pre-oxygenation with Optiflow to the pre-oxygenation achieved with face mask.

The use of high flow nasal cannula (HFNC) originated in neonatal care, and has become widespread in its application for patients that are high risk for hypoxemia, both in critical care and emergency settings. Therefore, high flow nasal oxygenation continues to be studied in airway management for preoxygenation, as well as maintenance of oxygenation in airway procedures. Optiflow™, a humidified high flow nasal cannula, has already been shown to be useful in preventing desaturation during intubation in ICU patients versus the non-rebreathing mask, in addition to, prolonging safe apnea time in patients with potential difficult airways. Additionally, preoxygenation with HFNC prior to intubation of patients in hypoxemic respiratory failure has also been shown to decrease desaturation during apnea compared to preoxygenation with traditional bag valve mask. The morbidly obese patient presents a separate group of challenges to the anesthesiologist in regards to mask ventilation and intubation. Obesity (along with other factors) has been shown to contribute to difficulty with mask ventilation. Obese patients have altered respiratory physiology, including decreased functional residual capacity, increased oxygen consumption and lower tidal volumes, as compared to the non-obese patient. These factors contribute to obese patients potentially having a shorter apnea time before desaturating during induction of general anesthesia, as compared to the non-obese patient. Weight is inversely correlated with safe apnea time. Optiflow™ may provide an opportunity to prolong apnea time in the morbidly obese patient population. If demonstrated to be efficacious as a method for preoxygenation and prolongation of apneic time, this could provide a safer environment for intubation in this particular patient population.

Inclusion Criteria:

• Adult patients (≥ 18 years old) undergoing elective surgery requiring general anesthesia
• BMI > 40 kg/m2
• American Society of Anesthesiology (ASA) Physical Status II-III

Exclusion Criteria:

• Chronic hypoxemia (SpO2 <94% on room air or on home oxygen)
• Acute respiratory failure
• Coronary artery disease and/or congestive heart failure
• Moderate-Severe pulmonary hypertension and/or RV dysfunction
• Full stomach (recently eaten)
• Pregnancy
• Chronic pulmonary disease (specifically COPD or interstitial disease, NOT asthma)
• Respiratory tract pathology
• Facial Abnormality
• American Society of Anesthesiology (ASA) Physical Status IV-V