ABG treatments?

xtxrn, ASN, RN · Aug 28, 2011

what is the cause?

PayitForwardHolistic · Aug 28, 2011

Cause is unknown for both. Given the ABG results I had to determine the condition and write what assessments/history I would expect to see... and then follow through with how I would treat the patients condition. :confused:

xtxrn, ASN, RN · Aug 28, 2011

Cause is unknown for both. Given the ABG results I had to determine the condition and write what assessments/history I would expect to see... and then follow through with how I would treat the patients condition.

http://www.elmhurst.edu/~chm/vchembook/263respiratoryacid.html

This came up under "respiratory acidosis treatment", as well as another similar search....maybe the answers are in here. :)

brandy1017, ASN, RN · Aug 28, 2011

To be fully compenstated the ph needs to be in the normal range of 7.35-7.45. Uncompensted respiratory acidosis falls out of that range ie less than 7.35 which is dangerous because they can go into a coma or respiratory arrest, although I've seen people 7.31 or 7.32 they are alive, but in big trouble!

Nowadays we can treat them with bipap, ventilator, oxygen and IV bicarb as long as we recognize the symptoms, sleepiness, resp distress, hypoxemia for example.

papawjohn · Aug 28, 2011

Hello, PayItForward. I think that your question is kinda non-specific which makes it hard to help you out. Let me give you a couple of examples of people presenting in resp failure and how we'd help them, OK?

Worst situation: Sadly debilitated person, bad nutrition, COPD suffers a fall @ home and isn't brought to us until a day or two later. They've suffered tissue damage that has harmed their kidneys (called Rhabdomyolysis). And their COPD has gotten worse (no meds while down, no inhalers, O2 runs out). This person has lost both channels that the body uses for getting CO2 out of the body. The ABG might have a pH of 7.1 and a CO2 up around 100. (You or I would likely be dead with numbers like that -- but our Pt has compensated over the years and is awake but obviously in danger of dying pretty quick.)

So there's you UN-compensated ABG: ph 7.1, pCO2 100, pO2 50, Sat 60. The first priority is to move large flows of high-oxygen air through this poor soul's lungs. You want the pO2 up in the 90% range or better (because as bad as high CO2 might be -- it is a failure to get OXYGEN to the cells that kills our patient). We want rapid deep breaths and a tidal volume/minute volume as high as we can get it without injuring the tissues of the lung (AVOID excessive 'peak pressures' on the vent). You will simultaneously be giving large am'ts of IV Fluids to help the kidneys. One potential problem is that that fluid will move into the pulmonary circulation and cause Pulmonary Edema, so your listening to the lung sounds frequently and keeping diuretics on hand.

OK - so that person, before they fell, had 'compensated' ABGs. They took bronchodilators and inhaled steriods and had home O2 and didn't sneak TOO many cigarettes. And their kidneys worked. Don't forget that the renal excretion of H ions is a primary way that folks with limited respiratory function keep their pH in balance by lossing acid-causing ions thru urine. That's their COMPENSATION mechanism.

So this compensated person gets pneumonia. (More accurately...gets pneumonia AGAIN...cause the ER staff will know this person well.) He gets to be your patient and he has ABGs like ph 7.35, pCO2 70, BiCarb 45, pO2 65, Sat 88%. The correct interpretation for that set of numbers is 'compensated respiratory acidosis' -- because altho the CO2 is WAAAY HIGH, the combination of high bicarb and renal excretion have keep the pH within the 'normal' range.

Obviously, this person is finely balanced and might 'buy a vent' any time. You'll probably put him on a BiPap machine and give a lot of respiratory treatments. You'll evaluate for productive coughing and make sure that mucus plugs don't close off any airways. There will be cultures to collect and antibiotics to give.

You'll worry that when this Pt sleeps, it will be because of CO2 Narcosis -- because when the acidosis reaches abnormal levels the first tissue it affects is the Brain and the Pt become sedated, breaths slower, acidosis gets worse and soon you're hauling him off to the ICU to be intubated. Because he became UNCOMPENSATED.

Hope that helps.

Good luck to you

PapawJohn

allnurses Guide · Aug 28, 2011

Treatment of acidemia depends on the severity of the pH derangement and the cause. The question is a little awkward because if it's "fully compensated" then the pH is normal.. you would probably watch and wait and treat the cause. With uncompensated, you have a dangerous pH and you need to treat that as a first priority then address the cause.

GreyGull · Aug 28, 2011

The over simplified teaching of ABGs do an injustice to the bedside clinical health professional.

Many focus on the disease process of "COPD" without considering the many other pulmonary and non-pulmonary disease processes which are interconnected.

Treatment is not going to depend solely on the ABG. The anion and OSM gap must be considered when it comes to acidosis. The other lab data can also help determine if the results of the ABG are an early or later stage and determine the path of care. Sometimes a patient with a low pH can avoid intubation based on this data. We've also extubated patients post operatively with a less than ideal ABG by understanding the other data used for differential diagnoses.

Here's a little more detailed ABG interpretation.

http://www.thoracic.org/clinical/critical-care/clinical-education/abgs.php

http://revisemedicine.com/forum/medical-students/1947-guide-abg-interpretation-medical-students.html

For Respiratory Acidosis you may need to determine if it is hypoventilation from:

(taken from the above articles)

1. Chronic obstructive pulmonary disease

2. Neuromuscular diseases - e.g. Guillain-Barre syndrome, Myasthenia Gravis, Muscular Dystrophy

3. CNS depression - e.g. drugs (opiates, barbiturates), neurological disorders (trauma, brainstem disorders)

Or failure due to V/Q mismatching and hypoemia.

1. Atelectasis

2. Pulmonary edema

3. Pneumonia

4. Pleural effusion

5. Haemo/pneumothorax

Some of these you can help correct or influence as a bedside clinician. The support (O2, NIV, ventilator, positioning) offered will depend on the determined underlying disease process and the clinical symptoms determining the amount of "rescue" required.

Pulmonary Emboli is also another consideration but the ABG will probably appear as "hyperventilation" initially.

GreyGull · Aug 28, 2011

We want rapid deep breaths and a tidal volume/minute volume as high as we can get it without injuring the tissues of the lung (AVOID excessive 'peak pressures' on the vent). You will simultaneously be giving large am'ts of IV Fluids to help the kidneys. One potential problem is that that fluid will move into the pulmonary circulation and cause Pulmonary Edema, so your listening to the lung sounds frequently and keeping diuretics on hand.

You must monitor the intrinsic or auto PEEP and plateau pressures. High Peak pressures are also just one small part of the story. By knowing the plateau pressure you can make an informed decision about whether it is a problem with secretions, bronchospasm or compliance.

http://anesthesia.slu.edu/pdf/plateau.pdf

The CXR would be a necessity to determine the strategies for protecting the lungs to achieve the amount of oxygenation required. But then, initiating one of these strategies would come with a package deal of CVP monitoring, fluids, pressors and maybe a buffer depending on the etiology of the lung disease and permissive hypercapnia.

I would also still look at the other lab values to determine the correct path for treatment. Stabilizing with a ventilator is just short term or maintenance. It may only buy a little extra time.

GreyGull · Aug 28, 2011

I apologize for my lengthy posts.

To summarize, sometimes patients are "assumed" to be a COPDer or in exacerbation with sole focus on the respiratory component.

The clinical presentation and the ABG iare useful for the inital rescue but as the bedside clinician, the history, duration of overall illness and the acute situation must be considered and how it has affected the respiratory component.

If a COPD patient by confirmed diagnosis tells me has have been sick for 3 days, looks clinically stressed but has what some would think is a normal compensated ABG, he might be looking at a ventilator in his future rather than NIV.

CO2 narcosis should not be assumed to be just COPD or even too much sedation. Other major issues are missed due to the focus on the pulmonary issue for assessment and treatment and of course the "OMG they have COPD, hold the O2". Understand the difference between the rescue treatment and that which addresses the underlying cause which may not necessarily be pulmonary.

Lots of breathing treatments may NOT be the answer either and may harm more than help in some situations. Be careful when assuming all COPD patients need Albuterol and have it distract from what treatments should be done especially in the face of an MI or CVA which are sometimes overlooked.

Another issue which should be assessed before any NIV is initiated is a GI problem. You do not want to exacerbate vomiting or any situation where air in the gut with gastric distention or perforation might be a problem. Alcohol intoxication and NIV also do not mix very well but once the ABG is obtained or the patient snores you will usually hear someone yell "BiPAP STAT".

Do-over, ASN, RN · Aug 28, 2011

ABGs, acidosis, et al was really hard (impossible) for me to understand in school. None of it meant much to me until I started working with these patients. I remember learning how to analyze results, but I never knew what it meant.

I think the main things are - O2 (probably bi-pap to start), and treat underlying cause if possible.

papawjohn · Aug 28, 2011

My friend Do-Over. I agree completely that students are given a huge jumble of numbers and -- sadly -- not enough organization of those numbers to find real information. Numbers are NOT the same thing as information. So I try to help by using little vignettes that exemplify how treatments affect results, how to prioritize numbers, what to be careful of. We really ought to try to make things as simple (in the sense of well-organized) as possible.

Thanx

PapawJohn