Clinical Case 096: Abdominal Ambiguity

Gday. Another quick case from the surgical files!  This is a diagnostic case that plays out intra-operatively. Put your thinking caps on – when does your “penny drop”?

This is probably more for the Anaesthesia types, but there is plenty in here for the ED docs and even surgeons out there.  Here we go:

46 year old man, a traveller – on his way around the north of Australia.  Usually fit and well, working miscellaneous manual-labour jobs to pay his way.

This chap had hitched a ride into town the day prior from a remote camping spot. He had noticed some “crampy belly pain” overnight – so thought he would pop into town for a check up….

At triage he reports: intermittent, central abdo pain that has become more right-sided and severe over the past 12 hours.  He is feeling “full”, not wanting to eat, vomited once en route this AM.  He gets a “cat 3” score, a bed and an IVC.  The triage note simply says: “46yo M, ?appendix

The trusty RMO gets the history – thin, well smoker.  Not much PMHx, had an inguinal hernia repair 20 years ago – otherwise a virgin abdo. No meds, no other chronic problems.

Obs:  T = 37.6, pulse = 100,  BP = 120/60  RR = 18/min  He is reporting a pain score of 7/10.   His pain settles with 10 mg of IV morphine.

On exam: tender over much of the lower abdo, right-side more than left.  Percussion tenderness at McBurnie’s point.

I heard about this case when the phone rang in theatre – I was doing an Anaesthesia list for the local Gynae.  The ED team were pretty sure he would get a look in OT and it was nearly sundown – so they wanted to let us know not to close up shop for the day!  The surgeon had been called to review in ED….

Ten minutes later we got a call form the Surgeon – he wanted to get this chap on the table tonight.  Now this was an old school surgeon – one that was happy to call it clinically.  No imaging or bloods required.  The story and exam did fit nicely with Appy, he was sore enough to suggest it was progressive and needed something doing.  So off to OT…

Yes hard to believe, I know! There are still places where surgeons operate without definitive imaging – they are fun places to work!

My Anaesthetic assessment was pretty dull – same as the ED notes.  Thin, fit, normal airway, looked like a dream tube.  Was still breathing up with a bit of pain in the holding bay.  The plan was for a “quick open appendix”.  Love the old school surgeons – no laparosopic adventuring when it is keeping us all out of bed!

Induction went well on 100 mcg fentanyl, 100 mg sux and enough propofol to do the trick.  Tube fell in easy and onto the vent….   now our first clue that something is awry.   The end-tidal CO2 on the first few vent cycles  comes back at 23 mmHg.

What does it mean?  We love the ET CO2 in Anesthesia-land.  You get A, B and C in a single squiggly line!

Airway is good – tube was easy, position check is OK, and we are seeing regular rise & fall of the CO2

Breathing seems OK – chest is moving well, the vent is happy with nice, skinny low pressures and we are reaching target volumes and a sensible MV.  SpO2 is 100% for what it is worth.  He was not bagged in the 25 seconds of apnoea…

Circulation – is the CO2 low because he has crappy output?    Nope – the BP is still 120/60,  pulse is 75 – hasn’t gone brady.  Looks like he is well perfused.  The volatile is washing in and he is peripherally flushed & pink.

So – why is the CO2 so low?  Sure he was breathing up pre-op… thought that was pain – nothing a slug of fentanyl shouldn’t fix???

Anyway – onwards – the Surgeon is true to form – he has cracked open the gridiron incision.  However, as he opens the peritoneum he starts to mutter…..  Occasionally we gas docs do wonder what it is that is going on down that end.  So I lean over the drapes for a gander – hmmm.  There is a good volume of haemoserous fluid pouring out of the incision – the scrub nurse is sucking it up, we are up to 300 mls before it starts to slow.  That is a bit odd – not the norm for an appendix – no pus, just lots of bloody serous fluid.

To make conversation (and try work out what the heck is going on) I ask: “Have you ever seen that before in appendicitis?”   There is no answer, just some brow furrowing.  Our surgeon is clearly deep in thought and is now looking for the offending appendage.

Meanwhile at the brain end of the room – the ET CO2 is falling now with relatively low volume ventilation – it is now 22 mmHg… and the BP is not looking so hot – that is down to 80/40 with a tachycardia developing 110/min.  So I do what Anesthetic folk do – a few boluses of metaraminol.  This seems to help the numbers.  Odd – he didn’t seem that sick or septic pre-op, yet he is behaving like one of those really nasty, peritoneal sepsis type appendix disasters on the table.  Reassured by a good heart and ‘young’ physiology I decide to wait & see what happens.

5 minutes later I peek over the drapes again.  Expecting to see an appendix with a few loops cast about it – I am disappointed to find the team preparing to open the midline.  A bigger cut, something is not right….
“Ahhemm! How is it going?”  I wonder.

The reply is along the lines of – well this is not appendicitis.  In true surgical form I am assured that we will know the diagnosis in a few minutes once the belly is properly opened.   Off I go looking for some longer acting paralytic – this is going to take a while!

OK.  SPOILER – I am about to reveal the diagnosis.  So take a moment to ponder your thoughts.  What else could be going on.  Not much to go on admittedly – as Vonnegut would say… “So it goes.”

About 4 metres of dead small boweldead gut.
 Suddenly the numbers all became clear – this was a seriously sick patient, compensating remarkably, but truly on the brink of collapse.

Time to change into the brown scrubs!  There is work to be done.

The CO2 was right all along – this is a guy with a good going metabolic acidosis, and a faltering cardiac output now thanks to my “routine RSI GA”.

First move – crank the ventilator.  We need to return the CO2 from whence it came – get that pH up ASAP.  But too much volume might kill the venous return – so I opted for a brisk RR and maintained ~ 6 ml/kg Vt.

Next – a big IVC, bolus of crystalloid.  I am a Hartman’s man when I am flying blind like this.  IS this the right thing to do?

I am not sure – the recent literature on fluid Resus and discussion in the FOAMed world has been controversial to say the least.  Is giving a big bolus going to do damage to this man’s fragile glycocalyx and lead to horrible organ failure win ICU in a few days?  Or is the Sevoflurane I am using going to protect his endothelium?  Should I use exogenous fluid bolus or use some pressors to squeeze the venous side and achieve the same ends?

I grab a VBG at the same time.  

pH = 7.05,  pO2 =40, pCO2 = 27, HCO3 = 10 BE = -12 Lactate = 7.7 Gluc = 8.0

It was at about this point I was recalling all the times I had derided the ED junior Docs for ordering all those “unnecessary” bloods and X-rays in the work up of belly pain.  Clearly this was the exception that proves the rule??

After a few litres of fluid – the BP is still pretty crappy and I have backed off on the volatile as much as I was comfortable.  I have used an amp of metaraminol by this stage – time to change plans.  I need to know what the heart is doing.  Is this an under filled heaving, healthy heart, or a sluggish poisoned pump?

So how does one go about making this call mid-operation.  Access is limited by the surgical drapes.  I can put a CVC into the IJ – but we all know that the CVP is a really silly number.  Still – it will be handy to run some pressors, and lets face it – this man is very likely going to a better place soon where he will certainly get one anyway!

Urine output…. a good thought.. but… there is no IDC in the bladder – this was going to be a quick in/out case.

So my plan of course involved ultrasound.  Instead of asking for the usual machine that lives in OT I really wanted the ECHO probe as well.

We do not have any fancy Cardiac Output monitoring devices – no oesophageal Doppler or USCOM etc.  However, in a thin guy on the table – a couple of parasternal ECHO views are usually achievable.  I reckon we can get an idea of the heart’s status with some reliability.  I am not suggesting we all do VTI and calculate the CO to 3 decimal places!  I just have an eyeball and say – is this heart hyperdynamic or underfilled, or is it hypodynamic.

Some information was forthcoming from my learned friend on the cutting side of the drapes – he noted that the ischemic bowel was full of haemoserous fluid – the mythical “3rd space”? There must have been 3 or 4 litres in what he was removing.

Unsurprisingly then the ECHO pics showed –  a really hyper dynamic heart with a collapsing LV – the EF was nearing 110%!  Ah – young patients – they can compensate so well without much to show on the surface!

OK – by the time the surgery was finished we had a 46 yo guy with a nasty ischemic gut.  He had lost about 75% of his small intestine.  An ileostomy was formed.

The metabolic acidosis had improved and I was able to wind back the vent a bit.  But the settings were :  RR 24, Vt = 440 ml with 5 of PEEP.  This was giving an ET CO2 of 33 and the latest ABG showed a pH of 7.25, lactate down to 3.1 and other numbers returning to normal.

He was loaded with opiates and ketamine and all the usual adjuncts for pain and nausea.

My question to you.  It is now 10 PM.  You are in a smallish hospital with no ICU.  The retrieval team have advised they won’t be there until after sunrise at best.

This is the dilemma – do you keep him tubed, ventilated and transfer to ICU tomorrow?  Or do you wake him up – run the risk he might hypoventilate and decompensate his acidosis in recovery… but free him from the potential downside of prolonged intubation etc.  Transferring him awake is much safer from the flight team’s perspective.

Oh – and why did he get dead gut.  Well I could tell you, but it would be more fun if you guessed – let me know your thoughts on the comments below!

Lots to discuss on this case.  Break your comments down into: Diagnostic, Biases / errors, Critique of my approach and Disposition.

Casey

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