hello to all you pulmonary nurses out there, a group of my nursing school
buddies called me last night wanting to know what oxygen mask is more appropriate for a copd patient, all of us except one thought it was the venturi mask. our textbook, for all the money it costs, does not give a clear cut answer. could someone please satisfy "inquiring minds"? thanks a million and happy holidays
Oct 4, '05
Try to keep a COPDer's SaO2 88%-92% (which is a PaO2 of about 60 mmHg, the shoulder of the oxyhemoglobin curve). A baseline ABG might be nice, too.
BTW- remember this tidbit "40 50 60, 70 80 90" which means a PaO2 of 40 mmHg roughly corresponds to a SaO2 of 70%, 50 mmHg to 80%, and 60 mmHg to 90%. A PaO2 of 40 mmHg is end-organ damage.
Remember that a "true" COPDer is probably on home O2, so start with the home prescription (usually 2-3 L/m via nasal cannula) and titrate upwards carefully. Carbon dioxide retention causing hypoventilation is overblown, but it is out there. Quite often the patient will do it fairly rapidly right in front of you, though. If you don't have an ABG, look at the lytes. If the CO2 is above 30 they are possibly a retainer, so keep a close eye on them. Also stay away from sedatives in COPD.
Mouth breathing is a problem when calculating FiO2 using the 4% per L/m formula. Constant flow of oxygen into the reservoir of the nasopharynx is drawn into the lungs with each breath. Increased mouth breathing of room air will dilute the oxygen for a lower FiO2 overall, which is why a venturi mask (constant FiO2 at a constant minute volume) is the most certain way to deliver a particular FiO2. And yes, if a COPDer needs more than 50% FiO2 to maintain a SaO2 of 88% and are getting sleepy, they need a vent.
Last edit by rt2crna on Oct 4, '05