Dr Edi Albert / Director, Healthcare in Remote and Extreme Environments Program / University of Tasmania
Delivering advanced medical care in austere and resource deplete environments can be difficult with the constraints of a small medical kit bag and sometimes we are faced with hypotension unresponsive to fluid therapy alone.
In this succinct article our very own patron, Dr Edi Albert shares his recipe for delivering adrenaline as a vasopressor when faced with acutely unwell patients in the field.
Of note, this features as an interest article only for many unless you are trained and experienced with inotropes and remains a last resort treatment method in the field.
There’s no doubt that there has been a blossoming interest in expedition and wilderness medicine, and increasing opportunities to get involved in a range of settings from scientific maritime and diving expeditions to journeys across deserts and up into the high mountains. It isn’t surprising that many of those interested in pursuing this interest come from a critical care background. Although much of the time expedition medicine is about prevention, planning and primary care, patients can and do become very ill and it’s here where some knowledge and skill in higher level care is useful.
Modern medicine has become increasingly protocol and algorithm driven, which can work very well in a predictable and defined context, but leave you stumped when things are less predictable and well-defined. We are often told to “think outside the box”, but that can be hard to do when you have only ever seen what is inside the box. This article attempts to give you a glimpse of what might lie outside.
Consider the following case of a 67 year old woman who is a scientist on the expedition that you are accompanying as a medical officer.
You have the limited medical kit you might expect, but as you have an established base camp and road access, it is somewhat larger than if you were trekking. But no monitor, no point of care ultrasound (POCUS), no point of care testing (POCT), no infusion pumps, no ventilator and no ICU nurse to help you. It’s a bumpy 6 hour jeep ride to the nearest local clinic, and probably the same again to the nearest hospital that can provide a good standard of emergency care. And it’s unfortunately out of the question that there is a helicopter hovering somewhere nearby.
She looks unwell, pale, clammy and peripherally shut down. “Do the sepsis six” is jingling loudly inside your head and a sense of unease arises in your chest. A quick history tells you that she has had dysuria and frequency for several days but has been ignoring it. Her temperature is 39.5C, pulse is thready at the wrist and the portable monitor that you have doesn’t display a good trace but gives a reading of a heart rate of 125bpm and 81% oxygen saturations. You don’t really believe the oxygen saturations based on the tracing but equally you know that she is very unwell. You do have a urine dipstick available and despite her shocked state she manages to give you a small sample. Using the colour chart on the bottle it is immediately obvious that the stick has lit up like the proverbial Christmas tree. This, combined with a clear chest, no neurology and no skin signs, suggest that this is urosepsis. Although more used to practising medicine in temperate climes, you know that the tropical environment is one in which infections are more common and more severe. You decide that you should start broad-spectrum antibiotics – you only have a couple of vials of ceftriaxone and hope that the bugs will be sensitive. You pop in an IV cannula successfully, but knowing that if you are struggling you can still give the ceftriaxone IM mixed with 1-2mls of 1% lignocaine to reduce the pain of the injection.
After giving the antibiotics you give a 500ml fluid bolus followed by a further 500ml a little slower. You are now left with only one further bag of saline in your kit and are mindful that continuing pure fluid therapy in distributive shock may start to have adverse consequences. You go back to check the response of your initial treatment and find your patient still has a heart rate of 125 bpm and her radial pulse is difficult to palpate suggesting a systolic blood pressure in the order of 80mmHg. What next?
Take this opportunity for a pause in your reading and think what your next steps might be. Unfortunately the helicopter is still not an option and our patient remains in shock. Open up that box and have a think outside it. How can you modify and make do with the kit that you do have?
In Central Australia where I work from time to time (and recently brought to life by Dr Sam Goodhand in his article The Tyranny of Distance – A Flying Doctor in the Heart of the Outback – Adventure Medic) a slightly different version of this scenario plays out on a not infrequent basis. Our remote area nurses deal with septic Indigenous patients in small communities several hours away from a hospital on a regular basis. They are better set up than the jungle scenario with monitors and iSTAT for point of care testing, but certainly none of the bells and whistles of a hospital. Most patients do of course respond positively to a bolus of fluid, some paracetamol and a dose of IV antibiotics. However, when they don’t, we do know what to do next, long before a retrieval plane can land. We call it dirty adrenaline.
You made sure you had some vials of adrenaline 1mg/ml (1:1000) for treatment of anaphylaxis in your expedition kit bag and you’re well acquainted with the use of adrenaline infusions in the ICU, so now it’s time to combine them with a bit of “out of the box” medicine. You are going to set up a dilute peripheral adrenaline solution and run it through a normal giving set. Although this is a solution of last resort and might sound somewhat concerning, it is in fact a well tried and tested approach.
Here is what to do:
- Put 1ml of 1mg/ml adrenaline into 1000ml of normal saline.
Bingo, you have a 1 mcg/ml solution.
(Technically you have a 1mg in 10001ml solution but the error is not relevant in this situation.)
- Start with 1 mcg/kg/hr (1 ml/kg/hr) and titrate upwards to effect.
Don’t be shy, this is a technique of last resort. It is a very dilute solution compared to what you are usually used to and thus there is a much wider tolerance in the infusion rate.
- Calculate your hourly rate based on the patient’s weight as usual.
Dose: 1mcg/kg/hr = 70mcg /hr
Starting rate: 70ml/hr
Very simple maths for when your brain is potentially overloaded.
At this point you will be thinking about how you judge the rate using an ordinary giving set. There are two ways:
Drop factor calculation:
The Drop Factor
This is printed on the packaging of your giving set and tells you how many drops of fluid make up 1ml.
Common drop factors are 20 and 60.
Drops per minute = (volume of IV fluid prescribed / time to run in hours) x (drop factor / 60)
- Let’s say you have a giving set with a drop factor of 20. The drip rate for this 70kg woman will be:
70/1 x 20/60 = 23 drops per minute.
That’s a little under one drop every three seconds, and something you can realistically set up and check.
If you’re still struggling with the thought of giving IV adrenaline peripherally in this manner, then the idea of “winging it” in a time of dire stress, when you can’t remember the drop factor calculations will seem anathema. But think about it, the starting dose is 2 or 3 drops a minute and if the patient isn’t responding you can just double it to 5, then 10, 20 or 40 drops per minute. Remember, you have to give the patient a whole litre of fluid before they get 1mg of adrenaline.
The good news is that you are able to MacGyver your adrenaline infusion, the antibiotics kick in, she survives the night and is driven to the hospital 12 hours away at first light.
Of course it doesn’t have the finesse of an infusion pump – which is why it is ‘dirty’ adrenaline, but it is more than fit for purpose. It has been used many times in rural and remote settings for a range of life-threatening problems from sepsis to anaphylaxis and from complete heart block to a post-resuscitation treatment. It might just help you too one day.
For more information tap into this great resource:
Adrenaline (Epinephrine) Infusion PHC Remote Guideline, 2018.
Northern Territory Government, Department of Health