I recently had a patient who presented in profound acute renal failure with a BUN of >200, creatinine of 13.5, and critical pH of 6.7, on the brink of death...

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The only reason he was still alive is because he still had a strong enough respiratory drive to blow his CO2 down to almost nothing!

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When patients go into profound metabolic acidosis, their blood bicarbonate (a base) vanishes and they compensate by blowing off CO2 (an acid).

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This is why sometimes when patients are tachypneic and appear to be in severe respiratory distress, they may not actually have any intrinsic respiratory pathology at all.

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This patient was breathing 30 times per minute taking huge tidal volume breaths as his body was fighting to keep him alive with this respiratory compensation.

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What he desperately needed to save his life was emergent hemodialysis. But logistically this was going to take a few hours and eventually he would tire out and be unable to keep up this breathing.

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So we put him on BIPAP at 14/4, giving him a pressure support of 10 cm H2O. This accomplished 2 things:

1. It provided respiratory support to delay muscle fatigue

2. It allowed him to take even bigger breaths and he was now pulling Tidal Volumes of ~1,450 mL!

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Recall that Minute Ventilation(MV) = Tidal Volume(TV) x Respiratory Rate(RR)

His RR had come down to ~25 breaths/minute. So his MV was:

14,250 mL x 25 breaths/min = ~36,250 mL/min !

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Consultants were recommending endotracheal intubation and positive pressure ventilation.

The reason I wrote this thread is to get this critical resuscitation concept out:

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INTUBATION AND POSITIVE PRESSURE VENTILATION KILLS THESE PATIENTS!

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Why? It’s simple math.

For arguments sake let’s just say we intubated him safely and made it through the dangerous peri-intubation period.

Now what?

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We would NEVER have been able to even come close to matching his spontaneous minute ventilation with positive pressure on the ventilator!

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Say we put him on a TV of 800 mL (which by itself is very high and risks barotrauma from positive pressure!)

Now let’s calculate what his RR would have to be at this TV, in order to match his spontaneous MV:

36,250 mL / 800 mL = ~45 breaths per minute!!!

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Setting this patient’s RR anywhere close to 45 breaths/min on the vent would allow insufficient time for expiration and result in profound auto-PEEP and subsequent cardiac arrest!

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Any way you manipulate the numbers you will quickly realize that even coming remotely close to matching his spontaneous minute ventilation with positive pressure on the vent is literally impossible.

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So our patient continued pulling these amazing Tidal Volumes on BIPAP and eventually got emergent dialysis via a femoral Quinton catheter that we placed emergently.

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He survived and was never intubated.

The most critical decision in his resuscitation was the one NOT to intubate him. If we would have intubated him, in all likelihood he would have coded, died and everyone would have said “well he was just too sick.”

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Don’t get me wrong there will be times when you are absolutely forced to intubate these patients. But if you remain calm and patient these times should be rare.

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If you ever do have to intubate make sure you keep them spontaneously breathing, even on the ventilator.

But first please make sure you’ve done everything in your power to avoid having to intubate them at all.

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I share this case as an example of how intubation can be harmful and to show how in patients with critical metabolic acidosis who are compensating with respiratory alkalosis, it can be deadly.

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Remember this concept and share it with others and I promise you will save lives.

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