Infants of < 1500 grams of birth weight who require a > 1 week mechanical ventilation (breathing machine) or CPAP [continuous positive airway pressure] (oxygen at a high flow through the nose) may have prolonged oxygen requirements. The nasal cannula (oxygen through the nose at a low flow) is the most commonly used method of oxygen administration, despite a lack of data regarding its safety and efficacy. Low birth weight infants are vulnerable to obstruction from secretions and blood, as well as the presence of the nasal cannula. Partially obstructed nostrils greatly increase the work of breathing. Additional potential adverse effects include an increased need for suctioning, increased risk for systemic infection, and inadvertent positive end expiratory pressure (CPAP). No study has been conducted to evaluate the efficacy of the nasal cannula compared to an oxygen hood (plastic "hood" that is placed over the infant's head to provide oxygen) on gas exchange or infection.