I promised to put some summary notes on the site for those who attended my talk on ‘The REAL Shocked Patient’ for the Australian College of Ambulance Professionals on Tuesday 21st February 2012, so here they are:
Shocked patients are important – they comprise most of the ‘talk and die’ caseload that preoccupies pub conversations between emergency physicians
It’s easy to mistake these patients as less sick than, say, hypoxic ones, but oxygen delivery to the tissues doesn’t just depend on oxygen!
Here’s a dead wombat – someone in the audience knew a worrying amount about wombat anuses.
The 4 Hs and 4 Ts aren’t a very cognitively practical mnemonic for the causes of PEA arrest (which is an extreme form of hypotension)
I prefer the ‘3 plus 3’ rule, which breaks down the causes into three – volume, pump, and obstruction. Obstruction is further broken down into three causes, being tension pneumothorax, cardiac tamponade, and pulmonary embolism:
Let’s look at some cases of shock caused by volume deficit, pump falure, or one of the three causes of obstruction to the circulation:
Case 1: The hypotensive motorcyclist
His low back pain suggested pelvic fracture
Think of ‘blood on the floor and four more’ (chest, abdomen, pelvis/retroperitoneum, long bones) and consider non-bleeding causes such as neurogenic (spinal injury), tension pneumothorax, cardiac tamponade, and finally medical causes/iatrogenic (drug) causes.
Don’t underestimate the importance of pelvis and limb splinting as a haemorrhage control technique in blunt trauma
Ultrasound in flight made thoracic or abdominal bleeding very unlikely, and ruled out tamponade and pneumothorax
Although he was hypotensive, no fluids were given, as he was mentating normally and peripherally well perfused, with a radial pulse. If we gave fluid, we would titrate to the presence of a radial pulse (in blunt trauma) but we don’t want to ‘pop the clot’ by elevating the BP, or make him less able to form effective clots by diluting his blood with crystalloid.
Mortality in trauma sharply rises with systolic BP below 105-110, so recalibrate your definition of hypotension in terms of when you might be concerned, and which patients may benefit from triage to a trauma centre.
Case 2: The child crushed by a wall
Caution regarding lower limb infusions in patients with abdominal / pelvic injuries – the fluid may not get to the heart.
The classification of shock into four classes is crap. Never let the absence of a tachycardia reassure you.
Intraosseous is awesome, and EZ-IO has the best track record by far.
Case 3: The boy stabbed in the upper thigh
In penetrating limb trauma, prehospital options include pressure, elevation, tourniquet, and haemostatic dressings. Foley catheters have been used successfully in transition zones such as the neck or groin.
Case 4: Haematemesis
Should we apply the same principles of permissive hypotension to patients with ‘medical’ bleeding?
The Trendelenburg position doesn’t make a lot of sense – no need to head down the patient, although the act of elevating the legs may ‘autoinfuse’ a bolus of blood to the core circulation, and is recommended by some bodies as a first aid manoeuvre for hypotensive patients in the field prior to iv fluids.
Case 5: The overdose patient with a low blood pressure but otherwise fine.
When don’t I Worry about hypotension? When the patient is:
- With it
- Warm peripherally
- and (in hospital) Without a raised lactate
Case 6: Two cases of pump failure: STEMI and complete heart block
Adrenaline infusions can be simply made with a 1mg 1:10000 minijet diluted in a litre of saline and dripped through a peripheral line titrated to BP / HR / mentation / pulses.
In complete heart block (or other bradycardias) with hypotension, percussion pacing is an option of you don’t have access to transcutaneous or transvenous pacing. If you get capture, it’s as effective in terms of stroke volume as a pacing wire.
Case 7: Obstructive shock – tamponade cases
…with resolution of hypotension after drainage by emergency physicians who identified the tamponade on ultrasound, even though they didn’t suspect it clinically. It can be a surprise!
Case 8: Obstructive shock – tension pneumothorax
Patients are often agitated and won’t lie flat. They may complain of ‘tight’ breathing. Crackles and/or wheezes may be heard. The classic description of deviated trachea, absent breath sounds, and hyperresonance are the exception, not the rule. Be suspicious and always palpate for subcutaneous emphysema.
Don’t assume a needle decompression will work – there is debate about the best site but in some adults a standard needle won’t reach the pleural space. If you need to place more than one needle, go for it. As physicians, we do thoracostomies to ensure we’ve hit the spot.
Case 9: Obstructive shock – pulmonary embolism
A tough one prehospital, as the hypotensive ones need fibrinolysis. Fluid may help the hypotension but too much can overdistend the right ventricle which can then impair left ventricular filling, and worsen the patient’s circulatory state. Once again, ultrasound may be invaluable in highlighting PE as a possible cause for shock.
Case 10: Penetrating trauma to the ‘box’ – chest and upper abdomen.
If these patients arrest due to tamponade, early (< 10 minutes) clamshell thoracotomy can be life saving, which means it may need to be done pre-hospital by a HEMS physician to provide a chance of survival. Be on the look out for these and if in doubt activate a medical team (in New South Wales). Like with tension pneumothorax, these patients may be extremely agitated as a manifestation of their shock.
Case 11: Confused elderly male with pyrexia and smelly urine who appears ostensibly ‘normotensive’
…but how many 82 year olds do you know with a BP of 110/57? His acute confusion may be a manifestation of shock and he needs aggressive evaluation in hospital including a lactate measurement. Don’t be afraid to give this guy fluids in the field – you can make a big difference here.
Here are five of the myths I promised to expose:
So…shocked patients can talk and die. Don’t let that happen. Shocked patients can be normotensive, and hypotensive patients might not be shocked. Have a plan for how you might evaluate the 3+3 causes in your setting and what you can use from your medication and equipment list to manage volume, pump, and obstruction issues. You will save many lives if you become a serious shock detective.