A vasovagal response may be observed with needle phobia upon insertion of the needle therefore reducing blood pressure, heart rate, stroke volume and cardiac output.
However a study (Finsterer, 2004) showed that needle EMG did not affect blood pressure or heart rate.
Can anyone provide any more evidence or explanation of what would happen?
https://www.ncbi.nlm.nih.gov/pubmed/14962781
Hi Terun,
What an excellent question. I will give you two answers, one based on my clinical experience, the second based on research.
Clinically, young healthy patients, particularly men, seem to have a greater frequency which correlates with intravenous insertion, and the size of the cannula. Larger cannulae and the "sight of blood" will frequently result in vasovagal syncope, easily treated by placing the litter flat, administering fluids, and waiting. Rarely do they require either anticholinergics or sympathomimetics.
Just now looking at research and found this: Is vasovagal syncope a disease? by Paolo Alboni, Michele Brignole, and Ettore C. degli Uberti at Europace (2007) 9, 83–87 doi:10.1093/europace/eul179 which may be of help. Also Eur Heart J (2009) 30 (21): 2631-2671. DOI: https://doi.org/10.1093/eurheartj/ehp298 Guidelines for the diagnosis and management of syncope. The latter article describes
"Reflex syncope (neurally mediated syncope)
Reflex syncope traditionally refers to a heterogeneous group of conditions in which cardiovascular reflexes that are normally useful in controlling the circulation become intermittently inappropriate, in response to a trigger, resulting in vasodilatation and/or bradycardia and thereby in a fall in arterial BP and global cerebral perfusion.7
Reflex syncope is usually classified based on the efferent pathway most involved, i.e. sympathethic or parasympathetic. The term ‘vasodepressor type’ is commonly used if hypotension, due to a loss of upright vasoconstrictor tone, predominates. ‘Cardioinhibitory’ is used when bradycardia or asystole predominate, and ‘mixed’ is used if both mechanisms are present."
and, for your particular question, the following,
"‘Vasovagal’ syncope (VVS), also known as the ‘common faint’, is mediated by emotion or by orthostatic stress. It is usually preceded by prodromal symptoms of autonomic activation (sweating, pallor, nausea).
‘Situational’ syncope traditionally refers to reflex syncope associated with some specific circumstances. Post-exercise syncope can occur in young athletes as a form of reflex syncope as well as in middle-aged and elderly subjects as an early manifestation of ANF before they experience typical OH."
Hope this is useful
Cheers!
Rich
Hi Richard,
Thank you for your response.
In terms of the length of the vasovagal response do you know how long this would last. I am conducting a research study that is looking at the response of blood pressure to ingestion of anthocyanins. I am going to be taking venepuncture and therefore I wanted to know whether this would cause a change in blood pressure therefore affecting my results.
Terun
Hi Terun
Bad news; this response will cause a transient but significant drop in BP, which might skew your results. Good news; it is very transient, and venipuncture needles tend to be smaller than intravenous catheters, I suspect your problems from thsi should be minimal
Cheers!
Rich
Hi Richard,
Thanks for the response. I will just have to adjust the timings of my measurements!
Terun
Dear Terun Desai
I do not know what position you do puncture
But I have an experience about 26-year-old man in the supine position under full monitoring that after IV line insertion by small size needle, when I was explaining to him about local anesthesia and insertion of arterial line Suddenly, hypotension and bradycardia and cardiac arrest occurred but he resuscitated very fast. Then he told me about his needle fobia. Our survey showed this event was corresponding with our normal reaction to fear. So I think question about needle fobia before procedure may be helpful.
Terun,
In an attempt to mitigate the blood sampling stimulus from your study, you may want to place an intravenous catheter prior to your intervention. You will be able to obtain pre-intervention and post intervention blood sampling without the "needle phobia" neuronal input tainting your results since the stimulus will occur prior to your intervention.
Regards,
Christopher
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