LAUSR

We previously reported the successful use of Trans-nasal Humidified Rapid Insufflation Ventilatory Exchange (THRIVE) in optimising surgical views and access to facilitate head and neck endoscopic procedures; demonstrating that this technique can be safely employed in 95% of patients for up to 20 min. We highlighted two potential limitations regarding this technique. Firstly, unclear efficacy of THRIVE in patients with higher body mass index (BMI), with the potential requirement to terminate THRIVE prior to completion of surgery due to oxygen desaturation. Secondly, the potential risk of barotrauma caused by simultaneous high-flow nasal oxygen and face-mask ventilation. In their initial description of THRIVE, Patel and Nouraei postulated that an elevated BMI may limit effective THRIVE time (TTHRIVE), due to both a decreased functional residual capacity following preoxygenation and increased oxygen consumption. Subsequently, Huang et al suggested that patient weight ≥ 80 kg or BMI ≥30 kg/m increased the likelihood of rescue ventilation and interruption of the surgical procedure by over five-fold. More recently, however, these limitations have been challenged by Schutzer-Weissmann et al. To address the risk of barotrauma, the manufacturers of OptiflowTM have devised a Switch Flow Diverter mechanism which triggers an audible diversion of nasal flow (between 30 and 70 L/min) away from the patient when pressure is applied to the right-sided oxygen delivery apparatus (Figure 1), allowing safe face-mask ventilation to be initiated. We conducted an initial clinical evaluation of the Optiflow Switch interface (Fisher and Paykel Healthcare, Auckland, New Zealand) to see if this proposed benefit translated to clinical practice.