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Unit 4.1: Supplemental Oxygen Therapy Case studies. by Elizabeth Kelley Buzbee AAS, RRT-NPS, RCP. Case study #1 . Mr. Hall is a 45 year old WM who presents in the ER with rapid shallow breathing. He was standing in his backyard when the chemical plant exploded and started to burn.
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Unit 4.1: Supplemental Oxygen Therapy Case studies by Elizabeth Kelley Buzbee AAS, RRT-NPS, RCP
Case study #1 • Mr. Hall is a 45 year old WM who presents in the ER with rapid shallow breathing. He was standing in his backyard when the chemical plant exploded and started to burn. • How do you want to assess this person?
Answer: • Do vital signs for s/s of respiratory distress • Check his state of consciousness • Check his work of breathing • Listen to breath sounds • Perform pulse oximetry but remember that it will not pick up HbC0 • Do a co-oximetry reading
vital signs : HR 140 respiratory rate: 33 bpm • He is anxious but understands your questions • He is retracting and has nasal flaring • His breath sounds show diffuse crackles in all lobes consistent with chemical pneumonitis • Sp02 is 88% • HbC0 is wnl What do you want to do with this patient?
answer • Start him on supplementary 02 to treat the s/s of hypoxemia
Answer: • Without any history, it would be safe to start him on 1-2 lpm nasal cannula
Before you place this patient on 2 lpm nasal cannula, to make sure the device is working correctly you do what?
Answer: • You look at the flow meter; is the flow indicator in the middle of the ball? • You feel the flow coming out of the device on the back of your hand • You look at the bubbles coming from the humidifier • You check the connections: • Between the wall connection and the flow meter • between the humidifier and flow meter. • Between the humidifier and the 02 line
You put the nasal cannula in Mr. Hall’s nose and warn him about what?
Answer: • Fire hazards of 02 • Calling you if he feels the 02 is disconnected or that he feels short of breath
What is the approximate Fi02 of this device at this flow rate?
Answer: • Fi02 of nasal cannula can be estimated by adding 4% per each liter of flow to base line of 20%. • 2 lpm = [2 x 4] + 20% • 2 lpm = 28% Fi02
If he starts breathing any faster, what might happen to this estimated Fi02?
Answer: • The Fi02 will drop as his respiratory rate rises and more air is entrained.
Answer: • Redo vital signs • Redo pulse oximetry • Reassess him for increased work of breathing
Answer: • Not at this flow rate
Answer: • He have no history that indicated he has chronic hypoxemia nor that he breathes on a hypoxic drive, but at this flow rate, he is safe enough
After 10 minute on 2 lpm nasal cannula, Mr. Hall still is breathing at a rate of 33 bpm. • His Sp02 is still 88% and his HR is still 130 bpm • He is still retracting and flaring on 2 lpm nasal cannula • What do you do?
Answer: • Increase his 02 from 2 lpm to 3 lpm
Answer: • Repeat Sp02 • Reassess the vital signs • Reassess the work of breathing
You have increased Mr. Hall’s nasal cannula from 5 lpm to 6 lpm without any change in his appearance. • What do you suggest now?
Answer: • Do an arterial blood gas to make sure that he doesn’t need more than 02 • From the blood gas, calculate the Fi02 he needs
You increase the flow rate a few times and when you get to 6 lpm you switch to a simple mask. • Why?
Answer: • The flow rate at 6 lpm via the cannula may not be that comfortable • The mask holds the 02 in the reservoir so that the patient gets more 02 and less entrained air.
answer • 30% - 60% at flow rates of 5-12 lpm
The doctor looks at the Sp02 of 89% and orders him placed on 50% entrainment mask. • What is the total flow rate if the flow meter is set at 6 lpm?
Answer: • Based on the magic box at 50% there is 1.6 lpm air entrained per liter of 02 6 lpm 02 + [ 6 x 1.6] = 6 + 9.6 = 15.5 lpm is the total flow going to this patient
If Mr. Hall’s Ve is 14 lpm, is this flow rate adequate for him?
Answer: • No, for a high flow system, he needs his Ve x [i+e] usual I:E breathing spontaneously is 1:1 or 1:1.5 • So 14 x [1+1] = 28 lpm • He needs a total flow of 28 lpm • What can we do?
Answer: • Increase the flow meter from 6 lpm to 12 lpm to increase the total flow rate going to this patient
You get an ABG on 12 lpm 50% entrainment mask and the Pa02 is 45 mmHg. • What do you do?
Answer: • Based on the Pa02:Fi02 formula, you need to increase the Fi02 from 6 lpm simple mask to 88% Pa02 : Fi02 as Pa02 you want :Fi02 you need 45: 50% as 80 : x 45 x = .5 x 80 • 45 X = .88 Or 88% Fi02 needed is to get Pa02 about 80 mmHg
Identify the supplementary 02 device you need to deliver 88%
Answer: • To get an Fi02 of 88% you need to switch to a non-rebreather mask
How long can this patient stay on this device without suffering side effects?
Answer: • He is at risk of getting 02 toxicity if he wears Fi02 100% for 24 hours • And he can get into trouble with Fi02 70% within 2 days so he’s got about a day to get off this 02.
What can you do under these circumstances to get him off NRM?
Answer: • He is in refractory hypoxemia. We need to wean his Fi02 back down to less than 50%. If we cannot do this-- then we need to consider other options such as mechanical ventilation or CPAP. For example we might put him on CPAP so that we can decrease his Fi02 below 50%
What might we have done in the beginning of this case study that would have avoided a lot of changes in therapy?
Answer: • We probably needed to get the ABG after the first 2 lpm nasal cannula didn’t work. • Also, in smoke inhalation, going straight to a NRM is frequently the first choice because [1] the patient may have CO poisoning [2] persons in chemical pneumonitis are frequently in refractory hypoxemia