Pharyngeal oxygen administration increases the time to serious desaturation at intubation in acute lung injury: an experimental study

Abstract

IntroductionEndotracheal intubation in critically ill patients is associated with severe life-threatening complications in about 20%, mainly due to hypoxemia. We hypothesized that apneic oxygenation via a pharyngeal catheter during the endotracheal intubation procedure would prevent or increase the time to life-threatening hypoxemia and tested this hypothesis in an acute lung injury animal model.MethodsEight anesthetized piglets with collapse-prone lungs induced by lung lavage were ventilated with a fraction of inspired oxygen of 1.0 and a positive end-expiratory pressure of 5 cmH2O. The shunt fraction was calculated after obtaining arterial and mixed venous blood gases. The trachea was extubated, and in randomized order each animal received either 10 L oxygen per minute or no oxygen via a pharyngeal catheter, and the time to desaturation to pulse oximeter saturation (SpO2) 60% was measured. If SpO2 was maintained at over 60%, the experiment ended when 10 minutes had elapsed.ResultsWithout pharyngeal oxygen, the animals desaturated after 103 (88-111) seconds (median and interquartile range), whereas with pharyngeal oxygen five animals had a SpO2 > 60% for the 10-minute experimental period, one animal desaturated after 7 minutes, and two animals desaturated within 90 seconds (P < 0.016, Wilcoxon signed rank test). The time to desaturation was related to shunt fraction (R2 = 0.81, P = 0.002, linear regression); the animals that desaturated within 90 seconds had shunt fractions >40%, whereas the others had shunt fractions <25%.ConclusionsIn this experimental acute lung injury model, pharyngeal oxygen administration markedly prolonged the time to severe desaturation during apnea, suggesting that this technique might be useful when intubating critically ill patients with acute respiratory failure.

Beneficial effects of humidified high flow nasal oxygen in critical care patients: a prospective pilot study

“…First of all, and most importantly, the same device is used all the way through, from initial management of respiratory failure right until per-intubation oxygenation. Second, the high constant flow probably provides sufficient oxygen to the alveoli during apnea, as previously described in a similar setting [15] and recently showed during intubation in an experimental study [16]. Fig.…”

High-Flow Nasal Cannula Versus Bag-Valve-Mask for Preoxygenation Before Intubation in Subjects With Hypoxemic Respiratory Failure

“…In an experimental model of respiratory failure, the pharyngeal administration of oxygen at a flow of 10 L/min delayed the time to severe desaturation during apnea. 13 With all other preoxygenation devices, the mask has to be removed during laryngoscopy, which deprives the patient of oxygen during the actual intubation procedure. This may explain the significant desaturation in the BVM group of our study and highlights the advantage of HFNC and its uninterrupted oxygen delivery.…”

“…11 Apneic oxygenation (ie, delivering oxygen to the airways and lungs without ventilation) has been shown to prolong the time to hypoxemia in subjects with healthy lungs 12 and in a model of acute lung injury. 13 In contrast to other techniques, the nasal cannulas for high-flow oxygen delivery do not interfere with laryngoscopy and therefore can be used to deliver oxygen during the apneic period of endotracheal intubation. 11 To our knowledge, until now, only 2 studies have evaluated the effectiveness of HFNC for preoxygenation before endotracheal intubation in critically ill subjects with acute respiratory failure.…”

High-Flow Nasal Cannula to Prevent Desaturation in Endotracheal Intubation

“…In a controlled trial enrolling critically ill patients in preparation for emergency tracheal intubation, Mort (2) found that after preoxygenation using bag-valvemask ventilation, Pao 2 increased by 50 mm Hg in fewer than 20% of the patients and concluded that preoxygenation is only marginally effective in critically ill patients. Under experimental conditions, Engström et al (3) have shown that pharyngeal oxygen administration given during apnea in simulated endotracheal intubation increased the time until patients became severely hypoxic but did so only when the shunt fraction was below about 25% on a PEEP of 5 cm H 2 O. In an animal study, Nielsen et al (4) found that they could fully oxygenate piglets with collapse-prone lungs only with a PEEP of 20 cm H 2 O.…”