Study of early warning for desaturation provided by Oxygen Reserve Index in obese patients

Abstract

Acute hemoglobin desaturation can reflect rapidly decreasing PaO 2. Pulse oximetry saturation (SpO 2) facilitates hypoxia detection but may not significantly decrease until PaO 2 < 80 mmHg. The Oxygen Reserve Index (ORI) is a unitless index that correlates with moderately hyperoxic PaO 2. This study evaluated whether ORI provides added arterial desaturation warning in obese patients. This IRB approved, prospective, observational study obtained written informed consent from Obese (body mass index (BMI) kg m −2 ; 30 < BMI < 40) and Normal BMI (19 < BMI < 25) adult patients scheduled for elective surgery requiring general endotracheal anesthesia. Standard monitors and an ORI sensor were placed. Patient's lungs were pre-oxygenated with 100% FiO 2. After ORI plateaued, general anesthesia was induced, and endotracheal intubation accomplished using a videolaryngoscope. Patients remained apneic until SpO 2 reached 94%. ORI and SpO 2 were recorded continuously. Added warning time was defined as the difference between the time to SpO 2 94% from ORI alarm start or from SpO 2 97%. Data are reported as median; 95% confidence interval. Complete data were collected in 36 Obese and 36 Normal BMI patients. ORI warning time was always longer than SpO 2 warning time. Added warning time provided by ORI was 46.5 (36.0-59.0) seconds in Obese and 87.0 (77.0-109.0) seconds in Normal BMI patients, and was shorter in Obese than Normal BMI patients difference 54.0 (38.0-74.0) seconds (p < 0.0001). ORI provided what was felt to be clinically significant added warning time of arterial desaturation compared to SpO 2. This added time might allow earlier calls for help, assistance from other providers, or modifications of airway management. Trial registration ClinicalTrials.gov NCT03021551.

Oxygen Reserve Index in Predicting Hypoxemia in Morbidly Obese Patients

“…We think that the reason why they found the added warning time so long, unlike us, may be due to the fact that they performed the study in ASA I-II healthy individuals and that they had long (6 minutes) preoxygenation and ventilation times, which provide better oxygen reserve. [17]. In our study, we found these values to be shorter, unlike Tymbal et al We think that the reason for this is that we accepted 94%, not 95%, as the endpoint for alarm time for SpO 2 and included more obese (BMI > 40 kg/m2) patients in our study.…”

Nonintubated bronchoscopic interventions with high-flow nasal oxygen

“…Our results on NIIB do not suggest that procedure time increases desaturation risk. Perioperative airway management and desaturation events are more frequent for obese patients [23] and are associated with a rapid decrease in oxygenation reserve [24] . Accordingly, supraglottic airway or tracheal intubation may be favorable for obese patients with difficult airway or obstructive sleep apnea.…”

“…Perioperative airway management and desaturation events are more frequent for obese patients [23] and are associated with a rapid decrease in oxygenation reserve. [24] Accordingly, supraglottic airway or tracheal intubation may be favorable for obese patients with difficult airway or obstructive sleep apnea. The required anesthetic depth for IBs is deeper than that for simple bronchoscopy requiring shorter time.…”

What is new in microcirculation and tissue oxygenation monitoring?

“…For impending hypoxemia , Tsymbal et al [ 22 ] studied 72 adult patients during induction of general anesthesia - of whom 36 were obese and 36 were non-obese. After pre-oxygenation and induction of general anesthesia, patients were kept apneic until SpO 2 dropped to 94%.…”