Shock and Blood Pressure

[LucidResq]

Yesterday I went to donate blood.

My pre-donation BP was 120/70 and my HR was 60.

After I donated I immediately felt really hot, sweaty, and woozy. I must've looked pretty bad because the phleb wouldn't let me get up, put me into trendelenburgs, placed moist towelettes, and kept a close eye on me.

Five minutes after I had finished my donation, he rechecked my vitals. My BP was 110/50 and my HR was 90. I expected the increased HR, but I didn't expect my BP to drop, especially not that significantly. I've always been told that a drop in BP was a late sign of shock that indicates the patient is decompensating.

Can anyone explain this? Was this due to something in the process of blood donation rather than the loss of blood itself?

 

[Ridryder911]

Sure, first you were not truly in shock. You had a sympathetic response. Similar to that causes syncope. Remember, the body has to compensate for the loss, as in the same as having vomiting, diarrhea, loss of interstitial fluid, etc.

The body went into a mild acetylcholine response, and with this pressure dropped. If you noticed, it regained itself with time. If you just laid supine, the body would have compensated and the blood pressure of course returns back to the baseline. Allowing the body regain homeostasis.

Chances are the loss of blood caused the receptors noting the loss and kicked in the response, constriction of the vessels (peripheral vascular resistance) and as well compensation of the supply per increase heart rate to meet the need.

In shock, there is cellular death because of the lack of oxygen and the consequences of this.

R/r 911

 

[pumper12fireman]

In addition to rid's post..who knows how accurate the BP was??

 

[LucidResq]

The body went into a mild acetylcholine response, and with this pressure dropped.

R/r 911

Wouldn't a response be determined by the receptors ACh acts on? In this scenario is the ACh acting on nictonic, muscarinic or both types of receptors?

Thanks for the info, by the way.

 

[jrm818]

This sounds like a vasovagal response to me - its a reaction to either the venipuncture or the thought of giving blood - and results in the up regulation of parasympathetic tone (and down regulation of sympathetic tone). That causes release of sympathetically moderated arterial vasoconstriction, thus decreasing blood pressure. Increased heart rate is the response to arterial-side baroreceptors compensating for the drop in blood pressure.

Vasovagal reflexes can cause all kinds of complicated mixed responses - but you were never in shock. Its unlikely that your body even noticed the change in blood volume - the venous-side baroreceptors are responsible for regulating blood volume, and aren't all that sensitive - its unlikely that you decreased their baseline firing very much if at all.

The reason decreasing blood pressure is a late sign of shock is because it indicates that all the compensatory mechanisms in the body have failed. There are incredibly potent chemical cascade systems that the body deploys in a severe state of hypovolemia that can keep blood pressure pretty normal for a good amount of time - but if too much volume is lost for whatever reason, blood pressure will eventually fall. Rest assured you were no where near overcoming the compensatory mechanisms.

As for the types of receptors - nicotinic receptors are involved as the ganglionic neurotransmitter in both symp. and parasymp. systems. Vagal stimulation cauees an increase in Parasymp. drive, which involve post-ganglionically by muscarinic receptors.

The decrease in sympathetic drive is from a decrease in activation of the ganglionic sympathetic nicotinic receptors, and thus a decrease in activation of post-ganglionic adernergic receptors. An increase in sympathetic drive would cause activation of sympathetic nicotinic receptors first, which then activate the adernergic receptors - but that would increase blood pressure, so thats likely not what was going on here.

 

[MSDeltaFlt]

From looking at both of your pics, I still can't tell just exactly what your dimensions are. Chances are your body was taken back a little with the amount of blood loss over that short period of time.

How fast was the blood taken?

 

[rmellish]

Kinda sounds like the vagal response I had when the phleb. decided to infiltrate, then jerk everything around for awhile because it "certainly can't be my fault." :glare:

(You could drop a 14 in either anc. with your eyes closed on me.)

 

[LucidResq]

Thanks for the explanations.

I'm 5'5 140 lb.

My body definitely feels the effects of the temporary anemia. One day I made the mistake of donating blood before my SAR team's winter ops training, which involved an increase in altitude of about 5,000 ft and hiking up a glacier while carrying very heavy equipment.

It was such a strange, terrible feeling. I was sucking air like crazy and it was coming in easy but I just couldn't get enough.

 

[Ridryder911]

In reality you probably had a little combination, vasovagal (which is the same as postural and syncope) and a little hypovelemia (temporary form) Like MSDeltafit described that your body went into a mild reaction. This is not to unusual for this to happen. Usually, the old saying "the bigger they are".. Football players, and such assume that it will not affect them.

Thus the reason for lounge chairs, and punch & cookies afterwards to ensure glucose and fluids.

R/r 911

 

[seanm028]

I've given a few times. The only time I had a problem was when I did "Power Red", which is where they take twice as much blood (volume based measurement) as they usually do, separate them, and re-inject the plasma, keeping only the red blood cells. I felt weak for the rest of the day, and was told several times I looked pale.

A few days later, I went hiking through the mountains near my home... bad idea. It was like you said, I was sucking lots of air because I felt like I couldn't get enough. I also started getting a little dizzy and eventually decided to stop hiking.

I was on the very lower limit of what they'll accept in terms of donor body weight, and I don't think I'll ever donate just red blood cells again.

 

[Airwaygoddess]

Blood donation

Having volunteered for quite a few blood drives over the years. One thing is for sure, besides getting a set of pre and post transfusion VS, we always monitored the participants very carefully. We would have the donor get up very slowly, if they C/O feeling dizzy,we would put them back down on their backs with their knees raised up.( shock position)
Sometimes it takes folks a little time to recover, but once they no longer felt dizzy, and VS were rechecked, we would have the donors drink water, juice and encourage them to eat the snacks that were offered to them. Part of the blood donation process is also to advice the donors to drink extra fluids for the next 24 hours, no caffeine,or "power" drinks, and no strenuous exercising for at least 24 hours.
This is one of those lessons about life that has put you in the patient's place, Can you image how a medical patient would feel with hypovolemia....
It is a good deed that you did Luc!

 

[LucidResq]

This is one of those lessons about life that has put you in the patient's place, Can you image how a medical patient would feel with hypovolemia....

Yeah I was definitely consciously thinking about that as I started to feel funny. I noticed that I was becoming diaphoretic. My perception of what was going on around me was muddled and I felt uneasy. I tried to imagine that times 5 in addition to being freaked out and in pain.

Have you ever had someone pass out at a blood drive?

 

[Ridryder911]

Have you ever had someone pass out at a blood drive?

Everytime I work at one.. a hundred or so, it's just routine, usually at least 3-4 per each event. I used to supplement my income working for ARC bloodmobile.

R/r 911

 

[LucidResq]

Everytime I work at one.. a hundred or so, it's just routine, usually at least 3-4 per each event. I used to supplement my income working for ARC bloodmobile.

R/r 911

Is it always the people donating? Haha. I ask because I made the mistake of bringing my boyfriend (who has the weakest stomach in the world) to a drive with me and he nearly passed out just watching her get out the needle.

 

[Airwaygoddess]

Blood donation

Well if it is not from the donation its self, it is that big needle they use to get the blood out!! Yikes! ( p.s. Airwaygoddess hates needles! :wacko

 

[seanm028]

Does anyone know what gauge needle they use? I've been curious, as it looks like it's a pretty large bore. Also, they don't use catheters, right? They just leave the needle in until you're done?

 

[Airwaygoddess]

The bigger they are....

If I seem to recall, 18g to start, could be a 16, it must be large bore for 2 reasons. First this helps with the prevention of the break down of the red blood cells themselves, second, due to the density of the blood. You have heard of the term "blood is thicker than water" (p.s. Airwaygoddess Still really hates needles! YIKES! )

 

[BossyCow]

If I seem to recall, 18g to start, could be a 16, it must be large bore for 2 reasons. First this helps with the prevention of the break down of the red blood cells themselves, second, due to the density of the blood. You have heard of the term "blood is thicker than water" (p.s. Airwaygoddess Still really hates needles! YIKES! )

I have recently hit the gallon mark on my blood donations. Been giving since its been legal for me to do so. I have never had an issue with needles. I even volunteer to let people stick me for practice or when they need a stick for their certification. Truly doesn't bother me. High pain tolerance I guess.

 

[Outbac1]

I have recently hit the gallon mark on my blood donations. Been giving since its been legal for me to do so.

Good for you Bossy. Keep at it and you'll catch me. 68 donations which is I think about 32 liters or around 8 gallons. Anybody know just how much they take? Who's given more? I'm sure someone has.

 

[LucidResq]

Way to go Bossy. I'm gonna track you down in July when I take my IV approval . Nobody will offer their arm to me! I just don't get it.

Way to go to both of you for donating so much. I'm at about a half gallon.