© 2008 American Thoracic Society
Noninvasive Ventilation and Intubation of Hypoxic Patients: ICU versus Operating RoomTo the Editor:We read with interest the article by Dr. Baillard and colleagues on noninvasive ventilation (NIV) of hypoxic patients (1), but we are somewhat perplexed by their results. The authors found that 26.4% of patients experienced severe desaturation and that 23% of them required two or three intubation attempts; a second operator's intervention was necessary in 11%; and the incidence of Cormack Lehane (CL) classes 3 and 4 was 13.2 and 5.2%, respectively; for a total amount of 64% of slight to major difficulties. Although no information is provided about preprocedural airway assessment for ventilation and intubation difficulty (2, 3), these results represent dramatically high values if compared with epidemiological data: according to the Italian Guidelines, difficult laryngoscopy occurs in 1–4% in the general population, with a CL3 or CL4 incidence of 1 and 0.1%, respectively (2). Baillard and colleagues' results might mean that either the patient sample was statistically inhomogeneous (including a high number of "difficult" patients), or that important predictive parameters of intubation difficulty were underestimated or not considered, as both severe ventilation and laryngoscopic difficulties are generally easily predictable (2, 3). Interestingly, Souza and colleagues, in their letter (4) commenting on the article by Baillard and colleagues (1), propose laryngeal mask airway (LMA) as a potential intermediate approach for preoxygenation. The Italian Guidelines suggest use of LMA (or other extraglottic devices) as rescue in case of ventilation difficulty (2), but this affirmation should be considered in a different manner in the intensive care unit (ICU), where situations such as full-stomach or ALI/ARDS patients (requiring high inflation pressures for ventilation) could lead to LMA sealing capacity failure with risk for aspiration, air leak, gastric insufflation, or positive end-expiratory pressure (PEEP) loss. Last but not least, the danger of potentially difficult extraglottic ventilation in patients receiving endotracheal intubation for more than 6–8 days should not be underestimated, because of possible consequences of prolonged intubation (5), thus representing a limitation to LMA use in case of accidental extubation, the most common ICU airway-related accident (6). On the other hand, the suggested use of the LMA solely for the cannot-ventilate cannot-intubate scenario (4) could be restrictive, as LMA might represent a safe bridge in cases of predicted difficult intubation, allowing advanced procedures such as fiberoptic intubation through Aintree catheter during ventilation (2). The misleading belief that difficult airway management guidelines for the operating room might be naturally extended to the ICU results in an absence of dedicated guidelines for the ICU, which is a different setting. Indeed, in the ICU no time for preevaluation is available, conventional preoxygenation is not possible (1), and hypoxic thresholds are different. Patients cannot be awakened or intubation delayed in case of difficulty, whereas intubation failure or predicted difficulty could lead to alternative choices such as NIV or preventive tracheostomy. Baillard and colleagues show us not only that NIV-PS-PEEP preoxygenation raises ICU safety standards, but also that we should try to define behaviors, algorithms, and procedures in specific guidelines for the ICU, where difficult airways are likely to be defined differently than in other clinical settings.
AOU Policlinico
Policlinico Universitario A. Gemelli
AO Villa Scassi
Centro Cardiologico Monzino
Università di Chieti-Pescara
Università di Milano On behalf of the Società Italiana di Anestesia, Analgesia, Rianimazione, Terapia Intensiva e Iperbarica (SIAARTI) Difficult Airways Study Group FOOTNOTES Conflict of Interest Statement: M.S. has no financial relationship with a commercial entity that has an interest in the subject of this manuscript. M.A. has no financial relationship with a commercial entity that has an interest in the subject of this manuscript. A.G. has no financial relationship with a commercial entity that has an interest in the subject of this manuscript. G.M. has no financial relationship with a commercial entity that has an interest in the subject of this manuscript. F.P. has no financial relationship with a commercial entity that has an interest in the subject of this manuscript. G.F. is the inventor of the Frova Introducer (Cook Critical Care, Bloomington, IN), of Percutwist (Teleflex Medical, Research Triangle Park, NC), and of Frova Crico-trainer (VBM, Sulzan, Germany), all patents pending; for the Frova Introducer and Percutwist, he receives annual royalties from Cook and Teleflex. REFERENCES
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