Supplemental oxygen and nasal intermittent positive pressure ventilation

Abstract

When supplementary oxygen is necessary with nasal intermittent positive pressure ventilation (NIPPV), the optimal route by which it should be added to the ventilator circuit is unknown. We investigated the oxygen concentration received when oxygen was supplied at flow rates between 0 and 6 L·min -1 into the proximal ventilator tubing or the nasal mask whilst patients were ventilated with air.Eleven patients with stable chronic hypercapnic respiratory failure were studied. A calibration curve was produced for each by supplying different known oxygen concentrations through a Monnal D or DCC ventilator and measuring the arterial oxygen saturations achieved. Oxygen was then supplied into the ventilator tubing or nasal mask and arterial saturation again measured. The oxygen concentration received was estimated using the calibration curve. Tracheal oxygen concentration throughout the respiratory cycle was studied in one patient when oxygen was supplied by both routes.Peak inspired oxygen concentration occurred at end-inspiration when oxygen was supplied into the ventilator tubing, but at mid-inspiration when supplied into the nasal mask. However, there was no significant difference between the two routes in the inspired oxygen concentration achieved at all flow rates: 1 L·min -1 supplied approximately 31% oxygen; 2 L·min -1 37%; 3 L·min -1 40%; and 4 L·min -1 44%. Flow rates above 4 L·min -1 had little additional effect.In conclusion, oxygen supplementation during nasal intermittent positive pressure ventilation can be provided into the ventilator tubing or the nasal mask with equal efficiency.

BTS/ICS guideline for the ventilatory management of acute hypercapnic respiratory failure in adults

“…As for the best method of supplying oxygen, Padkin and Kinnear,63 in a study of patients who were not acutely unwell, reported no difference in inspired content whether delivered directly into the NIV mask or into the ventilator tubing close to the mask. Introducing oxygen at the ventilator end of the tubing was less effective.…”

Oxygen Supplementation in Noninvasive Home Mechanical Ventilation: The Crucial Roles of CO2Exhalation Systems and Leakages

“…[7][8][9] The effect of an altered oxygen flow on inspired oxygen concentration remains unclear in the clinical setting, as this is not regularly measured. Furthermore, conflicting results exist in the literature about whether F IO 2 is dependent on the location of oxygen insertion and the presence of leak 7,[10][11][12][13] ; this is most likely attributable to the fact that the majority of relevant studies were performed in vitro, using test lungs. [7][8][9][11][12][13] So far, no study has been performed in patients with hypoxemic and hypercapnic respiratory failure where the impact on gas exchange may differ substantially, depending on the underlying pathology.…”

“…11,12 One study found no effect of changing the position of oxygen insertion. 10 However, the insertion of oxygen near the ventilator is recommended by many manufacturers as well as guidelines, 6 and is suggested to be more convenient because the risk of disconnection is lower than when oxygen is inserted close to the mask. This rationale therefore supported the decision in the present study to insert oxygen near the ventilator, and different results by inserting oxygen at other ports could not be excluded.…”