View Full Version : COPD AND THE HYPOXIC DRIVE
04-28-2003, 11:15 PM
Ok guys, the reason I started looking at these message boards is to gain info that will make me a better EMT, and maybe share some of mine to make other good EMT"S. I see a lot of healthcare providers refuse to give COPD patients oxygen when they are SOB due to "the hypoic drive". In my research of the subject I have found that only about 1% of all patients with COPD actually have a hypoxic drive, however I only found this number in one book, has anyone heard this before? I also understand that the hypoxic drive is a last line of defence and that may explain the 1%. Its my personal feeling that if a patient has acute dyspnea you should provide high flow o2, do you agree, why or why not? Dose anyone know how long it takes for a patient with a true hypoxic drive to stop breathing? Feel free to share any other info you may have on the subject, thanks.
Tom Clements EMT
04-29-2003, 12:22 AM
Many of the patients we deal with have COPD, and we place many of them on oxygen. Any patient c/o difficulty in breathing or who presents with SOB is given oxygen (on the BLS level; ALS units may monitor saturation levels and administer oxygen accordingly). High-flow oxygen treatment on a patient with a hypoxic drive may cause a patient to stop breathing after a long period of time. It is something that hospitals need to worry about with their admitted patients, but it is not a main concern in the prehospital setting.
For long transports ("road trips") with COPD patients (i.e. hospital to hospital), patients with a suspected hypoxic drive will be placed on medical air (not 100% O2). Other patients' oxygen and carbon dioxide levels are carefully monitored. These calls are treated on a case by case basis.
It should be noted that the concept of a hypoxic drive (respiratory drive based on amount of oxygen in system, not amount of CO2 [norm]) in COPD patients is controversial. Very few COPD patients actually develop a hypoxic drive, and most of these patients do not fully rely on the hypoxic drive. Because a hypoxic drive can not be identified in the field, many protocols simply dictate that "careful patient monitoring" be done on patients who may have a hypoxic drive. (But shouldn't patients always be monitored carefully? ;))
Here is an example from the Delaware Paramedic protocols:
There are no absolute contraindications to the use of supplemental oxygen in the field; however, caution must be exercised in patients known or suspected to have a hypoxic drive, such as those with chronic COPD.Hope this helps. Stay safe. BRT
04-29-2003, 12:34 AM
In my EMT-B class we were taught that roughly 5% of COPD pts develop a dominant hypoxic drive. We were also taught to err on the side of supplemental O2. Basically if they have SOB or trouble breathing give them the O2. Without it they die, with it they might go into respiratory arrest, we can treat one and not the other!
04-29-2003, 01:13 AM
im glad to see so far we are all on the same page
04-29-2003, 08:48 AM
WESTERN VIRGINIA E.M.S. COUNCIL
G-12 - Oxygen Therapy Guidelines
The amount of oxygen administered should be based on clinical evaluation of the patient, i.e.: respiratory rate and depth, skin color and temperature, capillary refill, level of consciousness, lung sounds and history of present illness or mechanism of injury.
Oxygen should be delivered in a manner that maintains oxygen saturation (SaO2) levels of at least 92%. If pulse oximetry is not available, oxygen should be delivered using a non-rebreather mask at 15 LPM.
There are no absolute contraindications to oxygen administration. However it should be used with CAUTION with patients who are likely to have a hypoxic drive, i.e. emphysema and chronic bronchitis patients on continual home oxygen. In such cases, oxygen should
be delivered in a manner that maintains oxygen saturation (SaO2) levels of at least 92%.
For patients on home oxygen, continue their home oxygen delivery level EXCEPT in patients with signs of shock, cardiovascular or respiratory complaints. If pulse oximetry is not available, oxygen should be delivered to the potential hypoxic drive patient at 1 to 3 LPM via nasal cannula. Increased oxygen delivery may result in respiratory depression; be prepared to assist ventilation with a bag-valve-mask device. The decision to increase oxygen flow above the previous listed recommendations must be based on careful overall patient evaluation and assessment.
The following devices are commonly used in the pre-hospital setting:
1 LPM 24% 4 LPM 36%
2 LPM 28% 5 LPM 40%
3 LPM 32% 6 LPM 44%
10 - 15 LPM 80% - nearly 100%
Now - with all that garbage out of the way. The plain simple English is if the Pt. is c/o any trouble breathing or shortness of breath - throw the O's to them, just be ready to maintain an airway & ventilate if you happen to get one of those 1 percenters.
04-29-2003, 04:05 PM
Never withhold Oxygen from a hypoxic patient. Regardless if they have COPD.
04-29-2003, 05:34 PM
Never withhold Oxygen from a hypoxic patient. Regardless if they have COPD. After researching some state and local protocols, I have found this case to be true in most EMS systems. I have yet to find a set of EMS system protocols that does not have oxygen administered to a hypoxic patient. However, ALL of these protocols indicated that CAUTION should be used with COPD patients. For example, from Maryland's protocols:
Adverse Effects of Oxygen:
High concentrations of oxygen will reduce the respiratory drive in some COPD patients; these patients should be carefully monitored.
(1) Never withhold oxygen from those who need it.
(2) Oxygen should be given with caution to patients with COPD.
Many of these protocols also dictate that patients with COPD who are saturating above 92% need only be given enough oxygen to maintain that saturation level.
Here's where things really get messy...what do you do with a patient who has a confirmed dominant hypoxic drive AND who is severely hypoxic? These are the few patients who will actually stop breathing if given too much oxygen. According to many of these protocols, the treatment is to provide high flow oxygen and to bag the patient if/when they stop breathing.
Like Tom said before, this is one thread where everyone seems to be on the right track. :)
04-30-2003, 04:12 PM
Step 2 in the RI protocol for COPD:
Administer OXYGEN with the highest-concentration device tolerated.
Step 4: For patients with severe respiratory distress, administer epinepherine 1:1000.
04-30-2003, 10:59 PM
Its short and sweet...O2 wont kill em befor you get to the ERD so give them all you got! SOB is SOB, COPD or not they are still SOB.
If in the remote chance they did stop breathing...then your action is simple...bag them..an if you are bagging them what are they getting??100 % O2.
Never never withold O2 via NRB's or simples (if you use simples, i dont..NRB or NC thats it)
In all the years I have done EMS and my instructers have done EMS no one has ever seen Hypoxic drive kick in
05-01-2003, 04:06 PM
Isn't the first thing they teach in EMT Airway Airway Airway? That is true with MD protocol that Caution should be used in admin oxygen to COPD pts. You also have to look at your transport time. In my jurisdiction, our transport times are any where from 10-25 mins. If they stop breathing you can bag them or if necessary intubate them. Epi 1:1,000, nebulizers (MD is adding atrovent with the new protocols), and terbutaline, also help with the SOB. Also remember that the SPO2 reading isnt always acurate on the pulse ox. Take care and stay safe everyone.
05-05-2003, 01:57 PM
Sometimes you can get too much of a good thing and COPD pts are more susceptible to over oxygenation. With this population the practice of high flow oxygen many not be the most prudent practice. One has to assess the severity of dyspnea and treat accordingly, however one must remember that if you suppress their hypoxic drive its not only bag them. They will go on a vent and COPD pts have a historic difficulty in weaning. Also, the chance of and adverse event increases 6% for each hospital day. There is a long term consequences to this treatment, so be sure that trials of cannula's, venturi mask, or simple mask fail before resorting to NRB. If they're in resp. failure, then aggressive treatment with RSI and a tube may be your best treatment.
05-06-2003, 04:23 PM
Interestingly, hypoxic drive affects only approximately 10% of the COPD patient population; furthermore, only approximately 1% of COPD patients are sensitive enough to have their hypoxic drive blunted over the short term to induce apnea. (Reference - West et al. - Respiratory Physiology – check out your medical library).
In addition to your clinical assessment, SPO2 readings help guide your oxygen therapy – target therapy in the noncritical COPD patient to maintain SPO2 at 90 to 92%.
Whereas, critical COPD patients that are severely hypoxic should have high flow oxygen to meet their clinical demands. As a general rule for those requiring intubation and/or manual ventilation their SPO2 should be maintained at 95% or above. In the hospital setting, after their underlying cause for their acute exacerbation of their COPD has been determined and stabilized, weaning can occur.
Thankfully, the actual numbers of patients that have extremely sensitive hypoxic drive are the minority. I agree with the post regarding the difficulty in weaning COPD patients after mechanical ventilation; however this is generally the case after some period of mechanical ventilation and not in the short term. In individuals that do not have significant cause for respiratory failure, and by medical misadventure have their hypoxic drive blunted to the point of inducing apnea, they are often easy to quickly wean and extubate. Caveat – this is assuming their apnea has been adequately managed and no complications (such as barotrauma) have occurred as a result of either manual or mechanical ventilation.
Although guidelines are fine when looking at groups of patients, each patient’s therapy must be individualized to their clinical presentation. The fear of blunting hypoxic drive often is given inappropriate emphasis versus treating their hypoxia, especially by nursing staff. Conservative therapy is prudent for stable COPD patients, which includes appropriate oxygen therapy, bronchodilators (Salbutamol and Atrovent), and steroids if the system permits.
However, in critically ill hypoxic COPD patients – emphasis should be placed on treating hypoxia, based on the patient’s clinical presentation, and managing complications as they arise. As already posted, this might include RSI and manual and/or mechanical ventilation.
It is my clinical experience as both a Paramedic and Respiratory Therapist that more individuals suffer the risks of hypoxia than that of blunting hypoxic drive in most COPD patients. Perhaps we can change that by understanding the pathophysiology and management of COPD.
Question – has everyone heard about the complication of autopeep or intrinsic PEEP?
05-06-2003, 07:18 PM
Everyone has added fantastic comments and I just wanted to add a couple more.
1. Hypoxic drive patients will not stop breathing like a flick of a light switch because of over oxygenation. There will be a almost reverse like process of the respiratory failure process. Keep in mind that just like in the case of failure or arrest, instead of bagging, lower the oxygen concentration and maintain the SPO2. Or as stated bag the patient as needed.
2. Enough with the cookbook stuff. When it comes to these patients and the situations stated, yes follow protocol. But lets remember that sometimes our best friend is our clinical judgement.
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