Critical hemoglobin desaturation can be delayed by apneic diffusion oxygenation.

Abstract

Professor and Chairman of Anesthesiology; American University of Beirut; Beirut Lebanon (Baraka)Chairman (Salem)Research Associate (Joseph); Department of Anesthesiology; Illinois Masonic Medical Center; Chicago, Illinois;ninosj@aol.comTo the Editor:-We read with interest the article by Benumof et al. [1]and the related correspondence [2,3]concerning the development of critical hemoglobin desaturation after neuromuscular block with 1 mg/kg succinylcholine. Benumof et al. [1]suggested that achievement of functional recovery from succinylcholine block before significant desaturation is not a realistic possibility and a rescue option should be instituted aggressively and early, [1]whereas Bourke [2]considered that this assumption may not be entirely justified and may, in some cases, lead to premature or potentially hazardous interventions.We agree with the recommendations of Benumof et al. [1]that whenever attempts at tracheal intubation after preoxygenation and rapid-sequence induction of anesthesia fail, we should not wait for recovery from succinylcholine block. Ventilation must be promptly initiated because the risk of critical hemoglobin desaturation if apnea is prolonged is far more serious than the risk of regurgitation associated with controlled ventilation while cricoid compression is performed.To delay critical hemoglobin desaturation during apnea in a patient with a suspected difficult airway, we suggest combining preoxygenation with apneic diffusion oxygenation. This can be easily achieved by pharyngeal insufflation of oxygen throughout the period of apnea. [4]During apneic diffusion oxygenation, oxygen will diffuse from the lung to the pulmonary capillaries according to its concentration gradient. The oxygen molecules can diffuse from the pharynx into the alveoli, even in the “cannot-intubate, cannot-ventilate” situation, in which the airway may not be completely patent. The combination of preoxygenation and apneic diffusion oxygenation can be particularly advantageous in patients with a suspected difficult airway and in patients with a decreased safety margin secondary to decreased functional residual capacity (FRC) or increased oxygen consumption, or both, such as small children, pregnant women, obese persons, and patients with respiratory distress syndrome.Anis Baraka, M.D.Professor and Chairman of Anesthesiology; American University of Beirut; Beirut LebanonM. Ramez Salem, M.D.ChairmanNinos J. Joseph, B.S.Research Associate; Department of Anesthesiology; Illinois Masonic Medical Center; Chicago, Illinois;ninosj@aol.com(Accepted for publication September 2, 1998.)