Decreased Left Atrial Pressure (REVIEW)

A 23-year-old yoruba male is admitted to the hospital following a motorcycle accident. On examination, no bones appear to be broken, but there is extensive muscle bruising resulting in tissue swelling from increased capillary permeability. His arterial blood pressure is 80/40. He is awake and able to walk with assistance.
Based on this information, it is likely that which of the following will be decreased from normal and why?
(1) circulating levels of catecholamines (2) left atrial pressure (3) plasma aldosterone concentration (4) plasma renin activity

Accident

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Abdulsalam
Abdulsalam
1 year ago

[9/18, 16:29] Dr Genius: This is a case of hypotension because his arterial blood pressure is below normal,also the tissue swelling and increased in capillary permeability is probably due to release of histamine (it is also a vasodilator which will decrease the total peripheral resistance hence also decreasing the diastolic pressure)which also decreases the arterial pressure .
[9/18, 16:39] Dr Genius: Due to this low blood pressure, the baroreceptors are not stimulated which sends an inhibiting stimulus to the medulla which means that the sympathetic fibres are not stimulated thus decrease in circulating cathecolamines.
[9/18, 16:40] Dr Genius: Why I choose d is because the renal control is like the major factor which isπŸ‘‰
[9/18, 16:51] Dr Genius: The low blood pressure is caused because the kidney is not stimulated to produce renin which will covert the angiotensinogen to angiotensin l,before it is later converted by ACE in the lungs to angiotensin ll,which do act to increase the blood pressure to normal.
[9/18, 16:53] Dr Genius: Am I making sense or have been wrong alreadyπŸ™πŸ™πŸ™
[9/18, 16:58] Dr Genius: So there will be decrease in circulating cathecholamines and also in plasma renin activity (since there is no or low production of it)
[9/18, 16:59] Dr Genius: Therefore my answers are 1 and 4

LearnerXs
LearnerXs
Reply to  Support
1 year ago

Very true. I think the main confusion in the response is that an inhibitory stimulus on the nucleus tractus solitarius in the brain inhibits sympathetic firing.

But it actually increases sympathetic firing. The NTS has an inhibitory effect on sympathetic fibres, so anything that inhibits it indirectly stimulates the sympathetic nervous system.

Which explains why the response is incorrectly linking the hypotension to internal factors rather than external, thus the mention of decreased renin as another cause. In actuality, external factors are the main cause of the low BP, and these other processes are rather compensatory. (Attempting to increase blood pressure by increasing their activity.)

Aminu Umar ahmad
Aminu Umar ahmad
1 year ago

Definitely left arterial pressure
This is what is termed as physiologic response to trauma.
An average individual has about 4-5l of blood once an individual loses about 25% of blood due to either external or internal hemorrhage physiologic response occurs to prevent an individual to enter into shock this response entails
Due to lose of blood peripheral vessels which holds most of the blood reserve of the body dilates those reducing venous return to the heart. Also cardiac output reduces so the pressure in the walls of the atria reduces leading to the stimulation of baroreceptors in the walls of the receptors leading to reduction in the inhibitory action exerted on sympathetic system by the cardiorespiratory centres of the brain which later leads to release of adrenaline and noradrenaline which acts on the vessels as well as the heart leading to both increase in peripheral resistance and force of contraction this serves to stabilize the blood pressure as well blood flow to vital organs like brain. At the same time blood flow to the kidneys GIT and skin is reduced. Decrease in renal blood flow leads to decrease in GFR so leading to the stimulation of JG apparatus of the kidneys leading to release of renin which acts to conerts angiotensinogen into angiotensin 1 then angiotensin 2 this is also a potent vasoconstrictor as well as stimulator of the adrenal cortex to release aldosterone which acts to conserves sodium along with water. All this response help to restore the normal body hemostasis

Ishaqdyara
Ishaqdyara
1 year ago

For as a nurse I will only do d primary help to him.
Let’s wait for the doctors Comment 😁😁

Ishaqdyara
Ishaqdyara
1 year ago

For me as a nurse I will only do d primary help to him.
Let’s wait for the doctors Comment 😁😁

scmill3r
scmill3r
1 year ago

1. epinephrine
2.
3 Aldosterone and renin levels would be elevated… Based on the increase Levels of Cortisol secondary to ACTH elevation due to the hemorrhage… The renin would help with the blood pressure

LearnerXs
LearnerXs
1 year ago

So the man is injured > Extensive muscle bruising then led to swollen body caused by increased capillary permeability due to damage > Decreased blood volume due to less fluids in the blood > Decreased blood volume means decreased venous return > Decreased right atrial pressure. (Frank-Starling Curves explain this) > Decreased pulmonary circulation > Decreased left atrial pressure. Boom! Your answer.

To explain the swollen body better, the increased capillary permeability allows protein molecules and other solutes to seep out of the capillary and increase the ECF osmotic pressure. This makes it harder for the capillaries to reabsorb the fluids meaning more fluid will be retained in the ECF then normal. The starling equation makes the reason for this clear. Take note that bleeding wasn’t reported so the reduced fluids in the blood might be the major reason.

To confirm the rest, Decreased blood volume leads to decreased baroreceptor stretching in the carotid sinus and aortic arch > Decreased Glossopharyngeal and Vagus nerve firing to the Nucleus tractus solitarius > Increased sympathetic firing > Increased adrenal gland activity > Increased catecholamines (Trying to compensate for the low BP by increasing HR by acting on beta-1 receptors in the heart)

Also, decreased blood volume > decreased renal perfusion (blood flow to the kidney) > increased renin secretion by activation of Renin-Angiotensin-Aldosterone (RAA) system

The renin levels would be high, but not very much due to the fact that genes that need to code for certain proteins are needed in the RAA system and this can take days. So it should really spike only after.

Last edited 1 year ago by LearnerXs