Background:Apneic oxygenation by insufflating O2 through nasal prongs (NP) and nasopharyngeal catheter (NC) has been proven to be effective. We conducted this study to compare the relative efficacy of these two techniques in a simulated difficult airway situation.Objective:The objective of this study is to evaluate the influence of two techniques of apneic oxygenation (NP vs. NC) on the duration of oxygen saturation ≥95% during simulated prolonged difficult laryngoscopy.Methods:A randomized non-blinded study was conducted in 56 adult patients, 28 in each group belonging to American Society of Anesthesiologists physical status class I and II scheduled for elective surgical procedures under general endotracheal anesthesia randomized to either NC or NP group. After pre-oxygenating for an end tidal oxygen concentration of 90% and induction, ability to mask ventilate was checked and paralyzed with rocuronium. Apneic oxygenation using 5 L/min of O2 was established either by NP or NC. After laryngoscopy the laryngoscope was withdrawn to simulate a Grade 4 laryngoscopy and held in this position for an apnea time (T1) of 10 min with SpO2 maintained at ≥95% or until SpO2 dropped to < 95%, whichever is earlier. An arterial blood gas analysis was performed at the end of T1. Desaturation to < 95% were compared between the groups using Chi-square test (P < 0.05 as significant). Arterial blood gas analysis among those who sustained T1 for 10 min between the groups were compared using independent sample t-test (P < 0.05 was considered as significant). None of patients were excluded from the study.Results:In NP group nine patients desaturated as against none in the NC group (P = 0.001). Arterial blood gas analysis among non-desaturated patients was comparable with respect to PO2, PCO2 and pH.Conclusion:Nasopharyngeal catheter is a better device than nasal prongs in maintaining safe oxygenation during apnea in a simulated prolonged difficult laryngoscopy.
Introduction: The success of awake fibreoptic assisted intubation often depends on the adequacy of anaesthesia of the airway and patient comfort for the procedure. Aim: To compare the standard technique (nerve block) of airway anaesthesia with simple aspiration of lignocaine. Methods: Thirty patients in whom difficult airway was anticipated were randomly allocated into either Group A (Aspiration) and Group B (Nerve block). In Group A, 0.2 mL/kg of 1.5% lignocaine was trickled on to the dorsum of the tongue while the patient was encouraged to breathe through the mouth. In Group B, superior laryngeal nerve block and intratracheal injection of lignocaine was used. Fibreoptic bronchoscopy was then carried out by a consultant anaesthesiologist, who was blinded to the local anaesthetic technique used. The patient responses to instrumentation of pharynx, glottis and trachea, and tolerance of the endotracheal tube were noted. Results: Two cases were excluded from the study because of bleeding resulting in subsequent loss of visualisation of glottis through bronchoscope. There was no statistical or clinical difference in the patient responses between the two groups (P > 0.05) due to fibreoptic bronchoscope in the pharynx, larynx and endotracheal tube in the trachea or with regard to the use of rescue medications. Conclusions: Aspiration of 1.5% lignocaine (0.2 mL/kg) provides clinically comparable conditions for intubation as the nerve block technique for awake fibreoptic nasotracheal intubation in patients with anticipated difficult airway.
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