There are many different factors that affect the brachial artery blood flow. How does inflating a blood pressure cuff affect brachial artery blood flow? How long should you inflate the cuff to get an accurate reading? How do you know when the reading is complete and ready to be removed? How can you not hear the flow of blood through the brachial artery after fully inflating it? What happens to your arm when taking a blood pressure measurement? What is the purpose of inflating a cuff anyway, other than measuring your heart rate and oxygen saturation levels?”
Inflating Blood Pressure Cuff: There are many different factors that affect how much you inflate a BP cuff. For example, if someone has very hard skin or is overweight, they may need more inflation than somebody who doesn’t. You want some slack in their vascular system so there’s less chance of injuring them when measuring.
Muffling Blood Flow: The cuff puts pressure on the artery and muffs the flow of blood through it, so you can’t hear any sounds from the brachial artery. If your arm is in an awkward position or has been compromised for some other reason, then that may affect how much inflation they need to have a reading. How do you know when enough inflating was done? Normally there’s a clicking sound made by the stethoscope, which means that all arteries are fully inflated and ready to take their measurement.”
When do we inflate with air into something (like into our tires or balloons) what happens inside them? They expand! That’s exactly what happens inside your vascular system. When you inflate the cuff, it causes a momentary surge in your blood pressure because of the increase in resistance inside your arteries and veins. How does this happen? The cuffs are designed to take up space so that when they’re inflated with air, there is more volume without changing the diameter as much. This increases vascular resistance which raises blood pressure briefly.”
“When measuring for bp at any given site on our bodies, one needs to use their radial or femoral sites before the brachial or antecubital sites. The radial and femoral sites are measured with a cuff that is pumped up to the point of slight discomfort but no pain, while for the brachial site (the arm) we use a cuff inflated to 30 mmHg above systolic blood pressure.”
“When you measure blood pressure, the cuff is inflated to a point that’s 30 mmHg above your systolic or diastolic bp. To determine what this means for you specifically, just take whatever number your doctor says when they tell you your bp and add 30.” “The reason why we inflate the cuff so much higher than our actual bp reading is that it changes in response to where on our body it was first measured (radial or femoral sites vs brachial site).”
“The cuff also inflates the artery in your arm. The pressure within that inflated part of the blood vessel equals 30 mmHg above your systolic reading.”
“An even better explanation is given by Dr. Burt Berkson: “When we measure a person’s blood pressure, we inflate an appropriately sized cuff on their upper arm with air until it reaches about 130-150mm Hg – this is usually at or just below what most people would consider ‘high.’ This will cause some flow restriction in the brachial artery and reduce pulsations as shown from both arterial waveform recordings (O’Brien) and ultrasound images (Neubauer).” As soon as you inflate, it reduces blood flow. It’s not that it stops completely.
The length of time for which this decreased blood flow persists after deflation depends on the size of the cuff and how much pressure you use to inflate it.