Objective: To determine whether transtracheal catheter and reservoir nasal cannula contribute to maintaining adequate oxygen saturation during sleep, and to calculate the oxygen saving they allow compared to nasal prongs.
Design: A prospective study in which patients were randomly assigned to either nasal prongs or oxymizer device prior to transtracheal oxygen delivery. Arterial oxygen saturation was then monitored by a finger pulse oximeter during 8 h of sleep.
Setting: Pulmonary ward of 'The Hospital Universitari Germans Trias i Pujol, Badalona (Barcelona/Spain)'.
Patients: Fourteen stable hypoxemic (PaO2 50 +/- 6.9 mm Hg; PaCO2 51.5 +/- 9.3 mm Hg) COPD patients (FVC 44 +/- 19%; FEV1 26.5 +/- 11.5%; FEV1/FVC 44.9 +/- 9.7%) already receiving oxygen therapy at home.
Measurements: Pulmonary function test was performed. The lowest flow required to obtain an SaO2 at or above 88% for over 95% of the sleep time was determined for each type of oxygen delivery. Patients were not switched to the next type of oxygen delivery device until 3 reliable pulse oximetries had been obtained. The percentage of oxygen savings was calculated. Awake PaO2 was measured in patients using nasal prongs and transtracheal catheter while continuing to inspire oxygen at the same flow rate as when asleep.
Results: As expected, no differences were found in SaO2 measurements for the three types of oxygen delivery. Oxygen savings were 48.65% for the oxymizer device and 52.87% for the transtracheal catheter. Awake PaO2 was significantly higher (p < 0.04) in patients with nasal prongs than in those with transtracheal catheter at the flow rate required when asleep.
Conclusions: The oxymizer device and transtracheal oxygen delivery benefit hypoxemic COPD patients reducing oxygen use during sleep by around 50%. Higher PaO2 levels were necessary to prevent nocturnal SaO2 decreases in patients with nasal prongs than in patients with transtracheal oxygen delivery. Oxygen-conserving devices are reliable and advisable methods for nocturnal oxygenation.