#CriticalCare non-COVID teaching case:
An elderly man is admitted to the surgical ICU for monitoring after an uncomplicated kidney transplant. You notice this funny pattern on his arterial line tracing. What’s going on here? #FOAMcc#FOAMed 1/
What’s going on here?
2/
This is pulsus alternans: an alternating strong & weak pulse.
Based on the A-line tracing POCUS was performed that reveled a markedly reduced EF. Coronary angiography showed no obstruction and a diagnosis of stress CM was made. The patient recovered with medical therapies.
3/
At first glance, differentiating pulsus alternans from exaggerated pulse pressure variation (PPV) can be tricky
*pulsus alternans occurs every other beat
*PPV occurs with the respiratory cycle
Slowing down the display can differentiate: This is what increased PPV looks like 4/
Pulsus alternans was first described by Traube in 1872.
Despite 150 yrs of research, the mechanism is not precisely known.
There are two theories, related to either beat-to-beat variation in pre-load or in contractility.
The *pre-load theory* is that impaired contractility (causing a weak pulse) leads to an increased end diastolic volume at the next systole. With more filling, the next contraction ejects more blood (causing a strong pulse) due to the Frank-Starling principle. 6/
The alternative *contractility theory* is that residual cytoplasmic Ca2+ after a weak systole causes a stronger cardiac contraction on the next beat.
Whatever the mxn, pulsus alternans is associated with poor systolic function.
7/
🥡Points:
🫀Pulsus alternans on an arterial line tracing can be a useful diagnostic clue for decreased systolic fxn
1⃣📟 See this new ICU OnePager on arterial Lines for more onepagericu.com 8/
📚Historical/literary note:
DH Lawrence beautifully describes Pulsus Alternans in Sons and Lovers:
"…he felt her pulse. There was a strong stroke and a weak one, like a sound and its echo. That was supposed to betoken the end."
9/9
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Did he have a head CT? What did it show?
Did he have stitches? Tetanus shot?
The NYT ran nonstop stories about Biden’s health after the debate but can’t be bothered to report on the health of someone who was literally shot in the head?
To the people in the replies who say it’s impossible because of “HIPPA” 1. I assume you mean HIPAA 2. A normal presidential candidate would allow his doctors to release the info. This is exactly what happened when Reagan survived an assassination attempt. washingtonpost.com/obituaries/202…
My advice to journalists is to lookup tangential gunshot wounds (TGSW).
Ask questions like:
- what imaging has he had?
- what cognitive assessments?
- has he seen a neurosurgeon or neurologist?
- he’s previously had symptoms like slurred speech, abnormal gait - are these worse?
If you intubate you need to read the #PREOXI trial!
-n=1301 people requiring intubation in ED/ ICU were randomized to preoxygenation with oxygen mask vs non-invasive ventilation (NIV)
-NIV HALVED the risk of hypoxemia: 9 vs 18%
-NIV reduced mortality: 0.2% vs 1.1%
#CCR24
🧵 1/
Hypoxemia (SpO2 <85%) occurs in 10-20% of ED & ICU intubations.
1-2% of intubations performed in ED/ICU result in cardiac arrest!
This is an exceptionally dangerous procedure and preoxygenation is essential to keep patients safe.
But what’s the *BEST* way to preoxygenate? 2/
Most people use a non-rebreather oxygen mask, but because of its loose fit it often delivers much less than 100% FiO2.
NIV (“BiPAP”) delivers a higher FiO2 because of its tight fit. It also delivers PEEP & achieves a higher mean airway pressure which is theoretically helpful! 3/
Results from #PROTECTION presented #CCR24 & published @NEJM.
- DB RCT of amino acid infusion vs placebo in n=3511 people undergoing cardiac surgery w/ bypass.
- Reduced incidence of AKI (26.9% vs 31.7% NNT=20) & need for RRT (1.4% vs 1.9% NNT=200)
Potential game changer!
🧵 1/
I work in a busy CVICU & I often see AKI following cardiac surgery.
Despite risk stratification & hemodynamic optimization, AKI remains one of the most common complications after cardiac surgery with bypass.
Even a modest reduction in AKI/CRRT would be great for my patients. 2/
During cardiac surgery w/ bypass, renal blood flow (RBF) is reduced dramatically. This causes injury, especially in susceptible individuals.
But what if we could use physiology to protect the kidneys?
Renal blood vessels dilate after a high protein meal increasing RBF & GFR! 3/
77 yo with respiratory distress, RR 30, SpO2 80% on non-rebreather at 15 lpm
CXR & TTE are unrevealing
pH 7.58 / PaCO2 24 / PaO2 >500 / HCO3 22
MetHb 0% CarboxyHb 0%
The ABG looks like this:
The answer is sulfhemoglobinemia.
Sulfhemoglobinemia is a *permanently* modified hemoglobin associated with exposure to TMP/SMX, dapsone, phenazopyridine, & other amino & nitro compounds.
It has an altered oxy-hemoglobin dissociation curve.
2/
Sulfhemoglobinemia is easily confused with methemoglobinemia. Both have very dark colored blood & present with cyanosis. Diagnosis typically requires a specialized lab.
Spoiler: you may have heard that SulfHb is green. It isn’t really. You’re thinking of Vulcans’ blood.