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At 04:10 23/11/99 , David Reinhard wrote: >Dear List, > sorry to have come in rather late on this discussion but I have been away >from my computer for a few days. I am sure there are many people on this >list who are better able to discuss legal issues than me, so i will stick >to the medical side of this debate. There are a number of points that need >to be considered. > > Firstly, any resuscitation system requires an interface between that >system and the patient. With resuscitators of any type this generally >invoves a face mask, which encloses both mouth and nose, and has a soft >rubber/silicone cushion designed to seal against the face. The ability to >achieve a good seal with this mask is probably the most important skill in >using a resuscitator. Without a good seal it will not be possible to >ventilate the lungs. Air/O2 will obviously follow the path of least >resistance so if the seal is not perfect (or near to perfect) then gas will >simply escape via that leak to the atmosphere and not into the patients lungs. > If using a scuba regulator as a resuscitation device this principle >obviously still applies. It would be necessary to place the mouthpiece into >the mouth in such a way that a perfect seal is obtained. Not having done >this on an unconscious person I cannot comment on whether or not this would >be easy to achieve. When pressing the purge button with the aim of >inflating the chest the gas will still of course follow the path of least >resistance. This means that the gas will predominantly vent out the exhaust >ports since the resistance in the airways and the need to expand the chest >will be much greater than the passage of gas out of the ports. It would >then be necessary to block both ports in order to achieve lung inflation. >If this was done manually it would obviously require two hands. Since the >nose also provides a path of lower resistance than the airways in the lungs >the nose must be pinched closed. To achieve this (ie blocking both vents, >pinching the nose) while pushing the purge button will require at least two >operators. > "Positive pressure ventilators" that work on a similar principle to a >"purge button" also require a pressure relief valve (typically set at >around 50-70cm H2O) to avoid overpressure injury to the lungs. This of >course is not present on a scuba regulator. The air flow from many >regulators (the Oceanic showerheads are a good example) is quite remarkable >and would pose a significant risk to the lungs. It would also be difficult >at these extraordinary flow rates to judge when to stop pressing the >button, since chest inflation would be very rapid. Another path of least >resistance, especially if the airway is not fully opened (a very common >fault with unskilled operators), is via the oesophagus to the stomach. >Inflation of the stomach would, I believe, be highly likely using a scuba >regulator in this fashion. Inflation of the stomach has two adverse effects >1) increased likelihood of regurgitation with possible inhalation of >stomach contents (potentially fatal) and 2) an inflated stomach puts >pressure on the diaphragm and thus limits the excursion of the lungs >reducing the ability to ventilate the lungs effectively. > The use of positive pressure ventilators has been gradually phased out >over the last ten years or so (in Australia anyway) in favour of bag and >mask systems. Bag and mask systems are capable of delivering close to 100% >O2 with greater contol over ventilation volumes and at generally lower >pressures than positive pressure ventilators. > Options for divers when treating a non-breathing patient are probably >primarily 1) bag and mask with or without O2, 2) EAR via a "pocket mask >with or without O2, 3) straight EAR (eg mouth to mouth. (EAR = Expired Air >Resucitation) > While I have been involved in probably several hundred resuscitation >attempts I have never done mouth to mouth. I would personally find it very >difficult to place my mouth over someone elses especially when covered with >vomit. Many of the people i have resuscitated have been heroin ODs and >quite frankly I would not take the risk of acquiring the diseases that >these people often carry. I have utilised a "pocket mask" for EAR when I >have not had equipment immediately available and found this to be a >relatively easy technique which would be well suited to a "lay person" with >minimal training. However, normally I use a bag and mask system which I >feel is the best alternative for a trained operator. However if you have >not been well trained, and maintained your skills with regular practice, >the bag and mask may not be appropriate. > While it is desirable to deliver high O2 concentrations to a non-breathing >patient do not disregard the value of EAR just because it delivers only >around 17% O2. Many lives have been saved by EAR. It is far better to >effectively ventilate the lungs with 17% O2 than to improperly utilize >equipment (whether a properly designed ventilator or an improvisation with >a scuba regulator) and achieve little if any ventilation, or put the >patient at risk of further harm by lack of training/experience. > It is my opinion that from a medical viewpoint a scuba regulator has many >disadvantages that would exclude its use as a resuscitation device. I would >not personally use it. In fact you are probably taking a legal risk using >any device that you have not been properly trained for. So unless you have >received traning in the use of a scuba regulator for resuscitation (which >is highly unlikely!!) leave it alone. > > For those of you who think credentials are important I have been an >instructor in CPR and O2 use for over twenty years (accredited by the >National Heart Foundation and the Royal Lifesaving Society of Australia), I >have worked as a professional ambulance paramedic for 16 years, the last >five of which have been on Mobile Intensive Care Ambulances. Despite that I >do however recognize that my opinions are potentially fallible and I remain >open to anyones viewpoint if they can demonstrate any flaws in what I have >written above. > > >Regards, David Reinhard. David, when you paramedics turn up with a bag and mask system, I'll be happy and relieved to stand back and hand over to you guys. Same with Ms Nakamura and her boat with the O2 system and trained operators on board. But here's the problem. What do we do till you (and she) get there? There's me and my buddy floating in the ocean, with anywhere from 4 to oh, say, 30 minutes before the buddy is re-united with the boat, pulled from the water and put on the mask. We are both carrying oxygen with demand regs. You, Ms Nakamura and that loopy 'lawyer' Big von Bullwinkle, seem to share the opinion that we should ignore the oxygen we are carrying and the facility of the regulator, and attempt expired air resucutation instead. Floating in the water with a non-breathing buddy, waiting for a boat to turn up or while swimming the buddy to the boat to be hauled aboard, it seems that option is precisely about avoiding responsibility rather than taking immediate, effective action with the tools to hand. With your advice, no matter how well meant, you aren't actually helping us solve a serious and likely problem we may face. In fact, the usual "stand aside for the experts" line is the very thing that ensures helpless bystanders remain helpless. I'm know you have a lot more to contribute to this subject than any of the other naysayers. But unless you apply your knowledge to the problem of administering and regulating positive pressure oxygen through a diving regulator, then when faced with the likely scenario described above, some of us are going to have to figure it out on the fly. By the way, non-breather emergencies never happen next to an oxygen resucitation system. If they did, they wouldn't be emergencies. And anyone that puts one of those wet-breather shower-heads on an oxygen cylinder needs to re-consider their equipment choices. regards billyw -- Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.
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