Evaluation of regional lung ventilation in different surgical positions with electrical impedance tomography

Comparison between Standard preoxygenation and Transnasal Humidified Rapid-Insufflation Ventilatory Exchange (THRIVE) in Difficult Airway during Induction ofAnaesthesiaZ Belamaric, D Nagore, JP Jimeno, A Bilbao, T Garth, K PlummerDepartment of Perioperative Medicine, St. Bartholomewu2019s Hospital, London, UKBackground and Goal of StudySecuring the airway can prove to be a challenge for the anaesthetist and may require use ofdifferent tools and change of strategy. In this phase it is pivotal to improve the oxygenation andprevent desaturation.We compared THRIVE and standard preoxygenation during induction of anaesthesia in patientwith predicted difficult airways.Materials and Methods30 adult patients, undergoing elective surgery in whom the presence of difficult airway was knownor strongly anticipated based on unfavourable predictors (BMI>35, decreased thyro-mentaldistance, limited mouth opening, limited neck extension, Mallampati score u2265 3) were randomisedinto two groups:1) Standard 5 minutes pre-oxygenation (100% FiO2) + mask ventilation between intubationattempts2) THRIVE: 5 minutes pre-oxygenation with THRIVE (100% FiO2) at a rate of 60 l/min +continuous THRIVE until a definitive airway was secured.Induction was standardised for both groups as Fentanyl (2 mcg/kg) + Propofol (2 mg/kg) +Rocuronium (0.6 mg/kg) with background maintenance of Propofol infusion (0.3 mg/kg/min).Intubation was performed in all 30 cases by the same Consultant Anaesthetist.Primary end-point of the study was the number of desaturation episodes (SpO2< 92%) until adefinitive airway was secured.Secondary end-points included time to secure the airway, adverse effects (airway trauma,bradycardia, hypo/hypertension) and the number of laryngoscopy attempts.ResultsThe 2 groups were similar in demographic parameters.Mean baseline SpO2 was 97.8 % in both groups.The mean time to secure the airway was 161.9+/-49.6 sec for THRIVE and 166.7+/-54.7 sec forthe Standard group (p value =0.80).There was 1 adverse effect in THRIVE and 4 in Standardgroup (p value=0.24). The mean number of laryngoscopy attempts was 1.73 in THRIVE and 2 inStandard group (p value=0.5).The number of desaturation episodes was significantly different: no episodes for THRIVE vs. 4episodes for the Standard group (p value=0.03).ConclusionAlthough there was no statistically significant difference in the time or number of attempts to securethe airway or in the incidence of adverse effects, THRIVE significantly reduced the number ofdesaturation episodes. In our opinion THRIVE may prove to be an useful tool especially in cases ofunexpected difficult intubation.References-Baraka AS, Taha SK, Aouad MT, El-Khatib MF, Kawkabani NI. Preoxygenation: comparison ofmaximal breathing and tidal volume breathing techniques. Anesthesiology 1999; 91: 612u2013 6.-Baillard C, Fosse JP, Sebbane M, et al. Noninvasive ventilation improves preoxygenation beforeintubation of hypoxic patients. American Journal of Respiratory and Critical Care Medicine 2006;174: 171u20137.-Dixon BJ, Dixon JB, Carden JR, et al. Preoxygenation is more effective in the 25 degrees head-upposition than in the supine position in severely obese patients: a randomized controlled study.Anesthesiology 2005; 102: 1110u20135.-Griesdale DEG, Bosma TL, Kurth T, Isac G, Chittock DR. Complications of endotrachealintubation in the critically ill. Intensive Care Medicine 2008; 34: 1835u20134