how to decide an appropriate oxygen flow rate or percentage for the patient?

Pneumothorax, BSN, RN · Apr 23, 2012

Can anyone tell me how to decide an appropriate oxygen flow rate or percentage for the patient? For example,if a patient's Sa02 is 90% RR10 b/min GCS is 8. Do I commence oxygen at 6-8 L/min via a Hudson mask? Another example,If a patient's Sa02 is 88% HR 144 RR 45 b/min. Should I commence oxygen at 15 L/min via a Non-rebreather mask? How do I choose the flow rate and device of oxygen therapy for different patients? thx a lot.

If your patient is breathing at 10/min with a GCS of 8 ; you'll probably have to bag them.

I would probably bag the person at 45/'min bc they are hyperventilating and going to faint lol

NCRNMDM, ASN, RN · Apr 23, 2012

I'm a nursing student, so this is just my understanding of things. I could be wrong, and this should not be considered the final or expert opinion in the subject. In your first situation, with the GCS of eight, my concern is the patient's airway. With a GCS that low, is the patient able to maintain a patent airway by him/herself? If the patient is maintaining his/her airway, and the sat is 90% at 10 breaths per minute, then I would probably start oxygen at 4-5 L/min via a Hudson Mask/simple face mask. I would titrate the oxygen to maintain an O2 sat of 94% or greater. I would be prepared to bag the patient, and have the rapid sequence intubation box and crash cart nearby. That patient may not breathe spotaneously for long.

In the second example, I would need more information. Does this patient have COPD? If so, then they are a CO2 retainer, and it is this CO2 retention that serves as their respiratory drive. If the patient had COPD, I wouldn't feel comfortable applying a NRB at 15 L/min. If the patient had COPD, I would try and utilize a Venturi mask and titrate the FiO2 (fraction of inspired oxygen) to a percentage that maintained a decent O2 sat, but didn't wipe out the respiratory drive. Also, in someone with COPD or other chronic lung disease, you have to wonder what their baseline sat is? Does this patient usually hover around 92, or is their baseline sat higher or lower?

If we assume that the second patient is a completely health individual who presents to the hospital with a sat of 88%, HR 144, and RR 45, then yes, it's probably reasonable to apply a NRB at 15 L. You should, however, titrate that down to maintain a sat of greater than 94%. The NRB may be necessary for the immediate acute period of the patient's illness, but you may be able to convert to a simple face mask or nasal cannula once you treat the cause of the respiratory distress.

Over-oxygenating a patient can be almost as bad as under-oxygenating them, so it's a precarious balance. When you have someone on high flow oxygen, or have a patient with severe respiratory distress, it is important to obtain an ABG. The blood gas will give you a lot of information regarding oxygenation status. One key piece is the PaO2 (the partial pressure of oxygen). This measures how well oxygenated the blood is, and can give you clues about how your attempts to provide supplemental oxygen are going, and whether the patient has a continued need for high-flow oxygen.

For instance, let's suppose that patient two presents to the ED (chief complaint respiratory distress) with a sat of 88%, HR of 144, and RR of 45. You immediately apply a NRB and turn the oxygen to 15 L/min. After doing this, you instruct another nurse to hook him to the cardiac monitor while you obtain an ABG. Someone else obtains IV access. When the ABG comes back, it's abnormal, and you notice that the PaO2 is 54. You know that the normal range is 80-100, so you realize that this is extremely low. Because of this, the rest of the gas, and the patient's symptoms, you and the MD agree to continue administering high-flow O2 at 15 L/min.

After about 45 minutes of treatment, the patient's sat has improved to 97%, his RR has dropped to 20, and his HR is down to 95. You and the MD decide that it's time to draw a follow-up ABG. At this time you and the MD agree that it would probably be safe to try oxygen at 4-5 L/min via nasal cannula. You switch the oxygen over, and carefully monitor the patient for signs of increased work of breathing, increased RR, decreasing oxygen saturation, etc. When the ABG comes back, the PaO2 is 160, indicating that the blood is highly saturated with oxygen. This value indicates that the patient's condition has improved, and that you made the right decision by reducing the oxygen flow rate.

Like I said, I am no expert, and this is just my take on the matter. If I am wrong, I hope that someone corrects me.

akulahawkRN, ADN, RN, EMT-P · Apr 23, 2012

Can anyone tell me how to decide an appropriate oxygen flow rate or percentage for the patient? For example,if a patient's Sa02 is 90% RR10 b/min GCS is 8. Do I commence oxygen at 6-8 L/min via a Hudson mask? Another example,If a patient's Sa02 is 88% HR 144 RR 45 b/min. Should I commence oxygen at 15 L/min via a Non-rebreather mask? How do I choose the flow rate and device of oxygen therapy for different patients? thx a lot.

You have to look at your patient's presentation. Your 1st patient who has oxygen saturation of 90% and breathing 10 times a minute with a GCS 8, could probably do well with a low flow oxygen. My guess is that his problem is not oxygenation. Your 2nd patient leaves me with the impression of severe respiratory distress. The fact that this patient oxygen saturation is 88% tells me that this patient is compensating for something, probably oxygenation or perfusion problems. Just seeing that patient breathing that fast with such a high heart rate would pretty much drive me to place that patient on a high concentration of oxygen, typically via non-rebreather mask, at 15 L.

As patient presentation improves, I would want to wean the patient off the high concentration of oxygen until I found the right mix for him.

Deciding on which concentration of oxygen you should place the patient on is something that comes with and from experience...

nurseprnRN, BSN, RN · Apr 23, 2012

i hate to burst anybody's bubble here, but oxygen is a drug and amounts are prescribed by physicians, so it's not really your decision.

that said, you will never get an argument from me about the advisability of knowing the pathophysiology of any condition, and what to do as first aid. note that knowing spo2 is not adequate for the complete understanding of the situation; you need pao2 and paco2, ph, and bicarb for that. so...abgs all around. (note: sao2 is, by definition, an arterial measure. if you are using fingertip sensors for saturation, you are measuring spo2, saturation / peripheral)

1) sa02 is 90% rr10 b/min gcs is 8.

looks like more of a ventilation problem than an oxygenation problem per se, although of course the oxygen level is definitely low. and rate isn't everything; you need to assess depth too-- if these are kussmaul resps, ventilation might actually be adequate (though i wouldn't bet the farm on it). with the low gcs i think you need to worry about rising co2 levels increasing intracranial pressure, so you want to start hyperventilating this patient with a bag-valve-mask or increase his ventilator rate.

2) if a patient's sa02 is 88% hr 144 rr 45 b/min, this person isn't going to benefit by bagging, but he's gonna run out of gas pretty soon from working so hard to breathe and not getting "paid" for it in the form of better oxygenation. he will benefit from oxygen, and maybe even a bit of cpap /bipap support to head off intubation.

Esme12, ASN, BSN, RN · Apr 23, 2012

i think you'll like this reference out of a critical care nurses book.

[color=#1122cc]oxygenation without intubation

HouTx, BSN, MSN, EdD · Apr 23, 2012

I realize that the OPs scenario is probably based on an academic exercise but . . . I agree with GreenTea (as usual) and also want to point out that oxygen therapy is not an area of expertise for nurses. A situation this complicated should be handled by the physician working in conjunction with a qualified RT to develop a strategy/plan. The nurse's role would be to maintain the interventions spelled out in the respiratory plan of care.

Double-Helix, BSN, RN · Apr 23, 2012

It's true that GrnTea and HouTx said about oxygen being a drug and parameters being set by the physician. However, in nursing school, and in other areas of continuing education, nurses are asked to think outside their scope of practice in order to learn.

Consider ACLS and PALS courses. In these classes, nurses are given the opportunity to direct a simulated case as though they were the physician. They decide the amount of oxygen to apply, which medication to give and in what dose, and whether intubation, cardioversion or defibrillation in required. These are not decisions that fall under the nurse's scope of practice. But in order to become proficient in emergency situations, the nurse is asked to make these decisions.

Similarly, nursing school questions and cases often ask questions that are outside the nurse's scope of practice. Such as- "what medication would you give in this situation?" or "how much oxygen should be applied?"

psu_213, BSN, RN · Apr 23, 2012

I agree that students are often asked to think outside a nurse's scope of practice. However, there is way more to these situations that just GCS and pulse ox (at one of the sites where I did clinicals in school, the NM of the unit had a signed posted behind her desk that read "if you are obsessed with the pulse ox, you are chasing the wrong number"). For instance, in scenario 1, is the GCS only 8 because they were hit in the head, or they overdosed on drugs, or because their pCO2 is 65? In scenario 2, is the pt in SVT, or having a severe panic attack, or septic? Each of this situations have different treatments and different management of their oxygen needs. I understand that the scenarios are meant to get the students to think, but there is a whole lot more to each situation than just the information given.

If it is a school assignment, thats fine--it can be a helpful way to get you to think about oxygenation needs. Realize that their is more to the picture than just a few numbers, and be able to back up your answers.

nurseprnRN, BSN, RN · Apr 24, 2012

"scope of practice" is also dependent on standing protocols, which usually depend on a higher level of inderstanding and judgment on the part of the nurse. example: once i reached a certain competence level, i was routinely expected to manage ventilator patients based on abgs (when i assessed them as being necessary), including sedation levels, changing rate, fio2, and mode for weaning, adjusting trach and et tubes. we were also expected to be proficient at assessing and adjusting swan-ganz pa catheters, and doing cardiac outputs and subsequent calculations (e.g., svr/pvr) and adjusting meds as we thought appropriate.

then i moved and found a job as icu/ccu/stepdown charge nurse in a smaller hospital...and was astonished to discover that nurses weren't allowed to draw, order, or interpret abgs, and perish the thought of moving an et tube that had slipped down the right mainstem, weaning an awakening patient, or anything else. only the physicians could do any of that, and they sure as hell would not come in on off-shifts or during office hours. patient care, as a result, suffered on two levels: 1, the patients didn't get care timely, sometimes leading to tragic adverse effects, and 2, nurses didn't do any meaningful pulmonary assessments, because it didn't matter what they found since they couldn't do anything about it anyway.

it took me six months to get the icu committee (all physicians) to approve a nurse-led algorithm for weaning (which they would let only me perform) and teach abgs to these supposedly experienced "icu" nurses.

i don't expect nursing students to be able to think about all this stuff...but i hope to make them aware that it exists and is out there to learn and use.

guest042302019, BSN, RN · Apr 26, 2012

"scope of practice" is also dependent on standing protocols, which usually depend on a higher level of inderstanding and judgment on the part of the nurse. example: once i reached a certain competence level, i was routinely expected to manage ventilator patients based on abgs (when i assessed them as being necessary), including sedation levels, changing rate, fio2, and mode for weaning, adjusting trach and et tubes. we were also expected to be proficient at assessing and adjusting swan-ganz pa catheters, and doing cardiac outputs and subsequent calculations (e.g., svr/pvr) and adjusting meds as we thought appropriate.

then i moved and found a job as icu/ccu/stepdown charge nurse in a smaller hospital...and was astonished to discover that nurses weren't allowed to draw, order, or interpret abgs, and perish the thought of moving an et tube that had slipped down the right mainstem, weaning an awakening patient, or anything else. only the physicians could do any of that, and they sure as hell would not come in on off-shifts or during office hours. patient care, as a result, suffered on two levels: 1, the patients didn't get care timely, sometimes leading to tragic adverse effects, and 2, nurses didn't do any meaningful pulmonary assessments, because it didn't matter what they found since they couldn't do anything about it anyway.

it took me six months to get the icu committee (all physicians) to approve a nurse-led algorithm for weaning (which they would let only me perform) and teach abgs to these supposedly experienced "icu" nurses.

i don't expect nursing students to be able to think about all this stuff...but i hope to make them aware that it exists and is out there to learn and use.

sounds exciting. i'd love to be in that position. to use critical thinking on that level would really be interesting. scary sometimes i bet. what if this and what if that probably happens in your mind at times though.