Fingertip Pulse ox meter and DCS

[GJC]

I don't see how pulse ox would be helpful for lay rescuers. Your giving max O2 already, so what could you do if the pulse ox starts falling. Lay rescuers would only begin rescue breathing when the patient stops breathing.

For advanced rescuers, falling pulse ox would indicate the need for them to assist breathing with a bag valve mask and intubate.

 

[doctormike]

I don't see how pulse ox would be helpful for lay rescuers. Your giving max O2 already, so what could you do if the pulse ox starts falling. Lay rescuers would only begin rescue breathing when the patient stops breathing.

For advanced rescuers, falling pulse ox would indicate the need for them to assist breathing with a bag valve mask and intubate.

I don't think that we were discussing a situation where intubation would be available. This was about first aid during transportation, not after a patient was moved from a dive boat to any sort of EMS system or to a hosptial.

The idea discussed upthread (initiated by the OP's question) was that a first aid provider might be able to differentiate between isolated DCS and DCS associated with some sort of lung problem (e.g. near drowning, immersion pulmonary edema, etc..) by checking to see if the patient could maintain 100% O2 saturation on room air. This could help in making the decision whether to run 100% O2 as long as you could or to try to stretch out limited O2 supplies by providing lower levels of O2 for a longer time period. In this scenario, you wouldn't need continuous O2 sat monitoring, just a check at the start of first aid.

As per the published guidelines:

A system capable of administering a high percentage of inspired oxygen (close to 100%) and an oxygen supply sufficient to cover the duration of the most plausible evacuation scenario is highly recommended for all diving activities.

In situations where oxygen supplies are limited, and where patient oxygenation may be compromised (such as when drowning and DCI coexist) consideration should be given to planning use of available oxygen to ensure that some oxygen supplementation can be maintained until further supplies can be obtained.

 

[GJC]

I don't think that we were discussing a situation where intubation would be available. This was about first aid during transportation, not after a patient was moved from a dive boat to any sort of EMS system or to a hosptial.

The idea discussed upthread (initiated by the OP's question) was that a first aid provider might be able to differentiate between isolated DCS and DCS associated with some sort of lung problem (e.g. near drowning, immersion pulmonary edema, etc..) by checking to see if the patient could maintain 100% O2 saturation on room air. This could help in making the decision whether to run 100% O2 as long as you could or to try to stretch out limited O2 supplies by providing lower levels of O2 for a longer time period. In this scenario, you wouldn't need continuous O2 sat monitoring, just a check at the start of first aid.

As per the published guidelines:

A system capable of administering a high percentage of inspired oxygen (close to 100%) and an oxygen supply sufficient to cover the duration of the most plausible evacuation scenario is highly recommended for all diving activities.

In situations where oxygen supplies are limited, and where patient oxygenation may be compromised (such as when drowning and DCI coexist) consideration should be given to planning use of available oxygen to ensure that some oxygen supplementation can be maintained until further supplies can be obtained.

I still don't see Pulse Ox being helpful for first aid level rescuers. For DCS you don't need pulse ox, you're just going to give 100% O2 in all cases. If you don't have enough O2 and need to give lower than 100%, the pulse ox readings still don't help you in deciding what you're going to do because you are going to get readings of 100% the entire time the patient is on any O2 (even lower levels).

If you have a combination of DCS and a medical problem like drowning or heart attack, I think you still have to use O2 at 100% for the DCS problem and not reduce it.

If you have a pure medical problem like drowning or heart attack, then pulse oximetry would be helpful in being able to reduce O2 administration to lower levels. But that depends on the ability of first aid level rescuers to completely rule out any possibility of DCS being part of the patient's problem. The only time I can see this happening is before the first dive of the day or if the patient has not made a dive (like the boat captain).

A lot of times, there are advanced level providers on dive boats. I have been on boats where more than half the divers were doctors, nurses, and paramedics. Some of them bring their own first aid kits that include BVMs and a few have brought their own ET tubes and intubation equipment.

 

[doctormike]

I still don't see Pulse Ox being helpful for first aid level rescuers.

Yeah, we are just a few non-specialists spitballing about the OPs question. Still interesting to discuss

For DCS you don't need pulse ox, you're just going to give 100% O2 in all cases. If you don't have enough O2 and need to give lower than 100%, the pulse ox readings still don't help you in deciding what you're going to do because you are going to get readings of 100% the entire time the patient is on any O2 (even lower levels).

The point was that the recently published guidelines state that if DCS is combined with any condition where oxygenation may be compromised, then you should sacrifice optimal offgassing for some lower level of O2 supplementation if you don't have enough O2 to keep them on 100% until you hand them off to the next provider or get more O2. So you have to make a choice.

A pulse oximeter could help you make that choice by checking a room air saturation. If you have a room air saturation of 99%, you probably don't have an increased A-a gradient, or any sort of lung disease. In that case, if you suspected DCS, you would give 100% O2 by a demand regulator (in a conscious patient), even if you were going to run out before getting to the handoff. If you have a room air saturation of 80% (which is what I had when I had pneumonia), you would try to make your O2 last for the entire time of transportation.

Checking a saturation for most patients who are receiving supplemental O2 wouldn't be helpful because of the reason you cite, which is why we weren't discussing that. If you are desaturating despite supplemental O2 you are pretty sick and may need intubation, etc...

If you have a combination of DCS and a medical problem like drowning or heart attack, I think you still have to use O2 at 100% for the DCS problem and not reduce it.

Yes, unless you don't have enough O2, and that's why the published guidelines say that you should reduce it to make sure that you have some O2 for whole trip.

A lot of times, there are advanced level providers on dive boats. I have been on boats where more than half the divers were doctors, nurses, and paramedics. Some of them bring their own first aid kits that include BVMs and a few have brought their own ET tubes and intubation equipment.

Wow! I have never seen anything like that, and I have been on a lot of dive boats. You mean crew or passengers?

 

[uncfnp]

So doctormike. You are looking at a scenario in a complex patient with DCS and pulmonary compromise, such as drowning in the above example. In that instance it seems a question of adequate ventilation as primary consideration with DCS secondary. With the added complication of limited supplemental O2.

Then it becomes a question of maintaining adequate O2 levels while preserving supply. And yes, in this instance a pulse ox might well be useful. But I still question the typical real world use of a pulse ox for layperson who then must use clinical judgement to interpret the results and determine the appropriate theraputic response. Not to mention the difficulty of getting accurate readings in a water chilled extremity and knowing how to ensure the reading is indeed valid.

 

[GJC]

Yeah, we are just a few non-specialists spitballing about the OPs question. Still interesting to discuss



The point was that the recently published guidelines state that if DCS is combined with any condition where oxygenation may be compromised, then you should sacrifice optimal offgassing for some lower level of O2 supplementation if you don't have enough O2 to keep them on 100% until you hand them off to the next provider or get more O2. So you have to make a choice.

A pulse oximeter could help you make that choice by checking a room air saturation. If you have a room air saturation of 99%, you probably don't have an increased A-a gradient, or any sort of lung disease. In that case, if you suspected DCS, you would give 100% O2 by a demand regulator (in a conscious patient), even if you were going to run out before getting to the handoff. If you have a room air saturation of 80% (which is what I had when I had pneumonia), you would try to make your O2 last for the entire time of transportation.

Checking a saturation for most patients who are receiving supplemental O2 wouldn't be helpful because of the reason you cite, which is why we weren't discussing that. If you are desaturating despite supplemental O2 you are pretty sick and may need intubation, etc...




Yes, unless you don't have enough O2, and that's why the published guidelines say that you should reduce it to make sure that you have some O2 for whole trip.




Wow! I have never seen anything like that, and I have been on a lot of dive boats. You mean crew or passengers?

Understood. My database is updated.

Boats I have been on with lots of medical professionals have been on the North Carolina and Gulf Coasts. The medical providers were all divers paying for the trip. I tend to book during the week instead of weekends and like smaller boats with fewer divers. That may be a factor.

 

[doctormike]

So doctormike. You are looking at a scenario in a complex patient with DCS and pulmonary compromise, such as drowning in the above example. In that instance it seems a question of adequate ventilation as primary consideration with DCS secondary. With the added complication of limited supplemental O2.

Then it becomes a question of maintaining adequate O2 levels while preserving supply. And yes, in this instance a pulse ox might well be useful. But I still question the typical real world use of a pulse ox for layperson who then must use clinical judgement to interpret the results and determine the appropriate theraputic response. Not to mention the difficulty of getting accurate readings in a water chilled extremity and knowing how to ensure the reading is indeed valid.

Hah! Look, I'm not funding a startup here...

Of course there are all sorts of issues related to how something like that would be implemented... We are just discussing the OP's question. And to me it seems that this is a reasonable answer to that question.

According to recently published guidelines for pre-hospital care of patients with DCS, you are better off conserving oxygen and keeping some supplemental O2 on the patient for the whole ride if there is any lung problem interfering with oxygenation, even if that means less effective offgassing initially. I mean, that's just what it says. Maybe I'm reading it wrong, would be happy to hear your interpretation.

And one way to tell if someone has a problem with oxygenation is to check a room air sat. Is it possible that technical issues might interfere with that determination? Sure! But that doesn't mean that it's worthless. I have one of those little fingertip pulse oximeters. Works pretty well, and I was able to track my recovery from pneumonia and weaning from supplemental O2 this summer by doing exactly that (checking room air sats).

So unless you have a massive supply of O2 on your boat, you may well have to decide what to do - 100% until it runs out, or low flow for the whole ride. You have to make the call one way or the other. So why not get some data to help with that call. Especially since you may be in contact with a medical professional en route - they might want to know the sat as well.

 

[uncfnp]

Hah! Look, I'm not funding a startup here...

Of course there are all sorts of issues related to how something like that would be implemented... We are just discussing the OP's question. And to me it seems that this is a reasonable answer to that question.

According to recently published guidelines for pre-hospital care of patients with DCS, you are better off conserving oxygen and keeping some supplemental O2 on the patient for the whole ride if there is any lung problem interfering with oxygenation, even if that means less effective offgassing initially. I mean, that's just what it says. Maybe I'm reading it wrong, would be happy to hear your interpretation.

And one way to tell if someone has a problem with oxygenation is to check a room air sat. Is it possible that technical issues might interfere with that determination? Sure! But that doesn't mean that it's worthless. I have one of those little fingertip pulse oximeters. Works pretty well, and I was able to track my recovery from pneumonia and weaning from supplemental O2 this summer by doing exactly that (checking room air sats).

So unless you have a massive supply of O2 on your boat, you may well have to decide what to do - 100% until it runs out, or low flow for the whole ride. You have to make the call one way or the other. So why not get some data to help with that call. Especially since you may be in contact with a medical professional en route - they might want to know the sat as well.

Fair enough. Gosh knows I tend to over think things. They are certainly cheap enough and no real downside.

So the target Sp02 would be 100?

 

[doctormike]

Fair enough. Gosh knows I tend to over think things. They are certainly cheap enough and no real downside.

So the target Sp02 would be 100?

I guess if the room air sat was 98-100 I would assume that the lungs were oxygenating OK and not worry about making sure that the O2 lasted the whole ride. If it was below 90 I would try to keep some O2 going. These are sort of arbitrary - not based on any actual data. But a room air sat in the 80s is probably not normal.

 

[GJC]

I guess if the room air sat was 98-100 I would assume that the lungs were oxygenating OK and not worry about making sure that the O2 lasted the whole ride. If it was below 90 I would try to keep some O2 going. These are sort of arbitrary - not based on any actual data. But a room air sat in the 80s is probably not normal.

I'm pretty sure I remember from my last ACLS course that AHA doesn't recommend O2 administration unless pulse ox readings are below 94%. The administration goal is to give just enough O2 to get it above 94. This is for medical problems only, not DCI treatment. In real life in the hospital, it's not usual for 92% to be the goal. It depends on how hard it is to oxygenate the patient and what their baseline was before they got admitted (if known).