It was a slow summer afternoon at the hospital. I had wrapped up rounding on my list of patients & was looking forward to a good lunch. In the medical world, when you are having an easy time at work, you savor it because it tends to be temporary. Right after that thought, the phone-pager system went off with an alarm for “rapid response alert” and of course it was my patient!
I made it to the bedside within a couple of minutes to the sight of various nurses anxiously checking IV lines, pulse, temperature and blood pressure. Everyone looked real busy, except for the patient who was sitting up comfortably amused. My eyes darted to the digital vitals monitor – the BP read 80/40, heart rate 80s, Oxygen saturations 95% on room air. I shook his hand, asked how he was doing, said he felt “tired but good” and winced as the automatic BP machine squeezed his arm for a recheck. His nurse explained how on routine check he was noted as hypotensive, but he had no fevers or new symptoms. He was admitted a couple days ago for febrile neutropenia, had been improving with antibiotics. A repeat BP check came back at 85/50 (he had been running 120s/80s before). After requesting the nurse to start a bolus of IV fluids, I mentally started going over the possibilities of hypotension using our useful ‘SHOCKED’ mnemonic: Sepsis? No fever, tachycardia, not warm to touch, doesn’t look ‘sick’ or confused. Bleed ? Doesnt look pale, no tachycardia. PE ? O2 sats at baseline, no chest pain, no tachycardia, etc., etc. And then it occured to check the K of ‘SHOCKED’! Indeed, our patient’s BP monitor cuff was super tight, could barely pass a finger between the cuff and his arm when deflated. After readjusting the cuff, the BP reading came back as 110/80!
So what was happening? A tightly applied cuff will exert it’s own compression force on the underlying artery. Lets say the pressure on the brachial artery from the tight cuff wrapping was 30 mm Hg, then we would only need an additional 80mm Hg inflation pressure for the cuff to make it to 110 mm Hg pressure to completely compress the artery (110 – 30 = 80 ). Hence the machine recorded pseudohypotension in error with false low blood pressure.
💡 Always be aware of how inherent errors of a device that can give you false readings. Check & adjust the BP cuff to make it fits just snug – not too loose or too tight !
💡 ‘Don’t just treat numbers, treat the patient’ is a true cliche – look at the bigger picture always, will help you uncover errors. This patient did not look like a typical hypotensive patient !
💡What would happen if the cuff was too loose ?
Don’t miss any future posts. Subscribe on email 📩 or follow on Facebook 👍🏽 | |
