Patients admitted to Intensive care units (ICUs) with hypoxemic (Type I) respiratory failure often require respiratory support in the form of intubation and mechanical ventilation. Drop in SpO2 to below 70% (Critical hypoxia) while performing intubation increases the risk of arrhythmias, hemodynamic compromise, hypoxic brain injury and death¹.  Securing the airway rapidly without critical hypoxia or aspiration is often a challenge for intensivists. Moreover the margin of safety for desaturation is lesser with critically ill patients when compared to patients without pre-existing hypoxia.

              Preoxygenation is the standard recommendation before intubating patients in ICU because of the following reasons:

1.      Preoxygenation allows a safety buffer during period of intubation. It extends the duration of “Safe apnea”, defined as the time until a patient reaches a saturation of 88-90%, to allow for placement of a definitive airway.

2.       Rapid sequence induction (RSI) has been commonly employed in ICU, taking into account the high risk of aspiration of gastric contents in these patients².

 Several Preoxygenation techniques have been developed to prevent or limit the risk of desaturation during intubation. Non-invasive ventilation (NIV) for preoxygenation of patients with acute hypoxemic respiratory failure is associated with less hypoxemia when compared to preoxygenation with a traditional face mask with reservoir bag³. However, NIV mask has to be taken off after preoxygenation in order to perform orotracheal intubation. The hypoxemic patient doesn’t receive oxygen during this period, precipitating rapid desaturation, especially in patients with difficult airway.

    “Apneic oxygenation” has been described which allows continued oxygenation during the period of apnea. Apneic oxygenation extends the duration of safe apnea when used after administration of sedatives or muscle relaxants. Many strategies have been developed to provide apneic oxygenation such as NO DESAT (nasal oxygen during efforts securing a tube) using a nasal cannula set at 15 L/min, THRIVE (Trans-nasal humidified rapid-insufflation with ventilatory exchange) using a high flow nasal cannula at 60 L/min⁴

Though apneic oxygenation can be provided with nasal cannula, a patent airway is required for oxygen to reach the hypo pharynx and be entrained into the trachea. A nasopharyngeal airway can accomplish this airway patency especially in patients with obesity and Obstructive sleep apnea. Furthermore, studies have shown that HFNC (High Flow Nasal Cannula) oxygen therapy generates a flow dependant positive airway pressure by increasing end-expiratory lung volume, suggesting a possible associated alveolar recruitment.

   Nasopharyngeal airway as a means to allow apneic oxygenation and to enhance the continued positive airway pressure (CPAP) thereby promoting alveolar recruitment, has not been assessed and the possible benefits over simple nasal cannula with 15 L/min O2 flow for apneic oxygenation has to be established.

Therefore we undertake this study to compare whether providing CPAP through  Nasopharyngeal airway as a means of apneic oxygenation is effective when compared to traditional means of apneic oxygenation using Nasal prongs at 15 L/min while intubating hypoxic patients in ICU.