Hyper and hypo ventilation with PaCO2 levels

AgentBeast, BSN, RN · Mar 19, 2012

It's backwards.

allnurses Guide · Mar 19, 2012

i'm confused..... in my book it states
hyperventilation occurs when the paco2 is less than 35 mmhg and hypoventilation occurs when the paco2 is greater than 45 mmhg. that doesn't make sense to me.

is this a mistake or am i missing something?

wait... when you hyperventilate, you are blow off your co2 so the levels are going to be low.

when you hypoventilate, you are retain the co2, so the levels would be higher. this is also when you would have respiratory acidosis... right?

or am i confused now?

lol

NightNurseRN13 · Mar 19, 2012

That's what I figured.... If you have increased CO2 then you would be acidosis so you would want to "blow off" more CO2 (hyperventilation) and if you have decreased CO2 then you are alkalosis and would want to retain more CO2 (hypoventilation)

NightNurseRN13 · Mar 19, 2012

Ok, I think it's just a mistake in the book (Potter and Perry fundamentals) because in my med surg book (iggy as I call it) says the exact opposite.

allnurses Guide · Mar 19, 2012

Ok, I think it's just a mistake in the book (Potter and Perry fundamentals) because in my med surg book (iggy as I call it) says the exact opposite.

Yes, because low CO2 doesn't cause hyperventilation, but low CO2 is a result of hyperventilation.

Esme12, ASN, BSN, RN · Mar 19, 2012

Hyperventilation is breathing in excess of what the body means blowing off too much CO2 thereby LOWERING the CO2 level beneath 35 mmhg. Hyperventilation is breathing that is deeper and more rapid than normal. It causes a decrease in the amount of a gas in the blood (called carbon dioxide, or CO2). This decrease will cause a patient to be lightheaded, have a rapid heartbeat, and be short of breath. It also can lead to numbness or tingling in your hands or feet, anxiety, fainting, muscles spasms and cramping, and sore chest muscles.Hyperventilation causes the carbon dioxide level in the blood to decrease. This lower level of carbon dioxide reduces blood flow to the brain, which may result in the following nervous system and emotional symptoms.

Weakness
Fainting
Dizziness
Confusion
Agitation
A feeling of being outside yourself
Seeing images that aren't there
Feeling as if you can't breathe

Overbreathing can also cause the calcium levels to drop in your blood, which may result in the following nervous system symptoms:

Numbness and tingling (usually in both arms or around the mouth)
Spasms or cramps of the hands and feet

(Carpal Pedal syndrome....Hand or foot spasms: MedlinePlus Medical Encyclopedia)

Muscle twitching

Many different factors can cause chest symptoms with hyperventilation syndrome. Normally, breathing is relaxed. If a person over breathes, the lungs become overinflated. Without thinking about it, the person might use the chest muscles to expand the rib cage. This extra muscle work will feel like shortness of breath, and the person will have difficulty taking a deep breath. The chest muscles will become tired, just like the legs tire after a long run. The lowered carbon dioxide levels in the blood can cause squeezing of the airways, which then results in wheezing.

Hyperventilation Causes, Symptoms, Treatment - Hyperventilation Symptoms on eMedicineHealth

When you are breathing too fast or taking frequent deep breaths you blow off too much C02 there fore DECREASING CO2 levels dropping them below 35 mmhg.

Medscape: Medscape Access Hyperventilation Syndrome requires registration but it's free and a great resource.

HYPOVENTILATION

The respiratory system serves a dual purpose: delivering oxygen to the pulmonary capillary bed from the environment and eliminating carbon dioxide from the blood stream by removing it from the pulmonary capillary bed. Metabolic production of carbon dioxide occurs rapidly. Thus, a failure of ventilation promptly increases the levels of carbon dioxide measured by arterial blood gas analysis (PaCO₂) greater than 45mmHg. Medscape: Medscape Access

Hypoventilation Syndromes

Alveolar hypoventilation is defined as insufficient ventilation leading to an increase in PaCO₂ (ie, hypercapnia).

hypoventilation (also known as respiratory depression) occurs when ventilation is inadequate(hypo means "below") to perform needed gas exchange. By definition it causes an increased concentration of carbon dioxide (hypercapnia) and respiratory acidosis.

Medscape: Medscape Access Hypoventilation Syndromes Treatment & Management

Breathing too slow or with peroid of apnea (as in sleep apnea) caused the CO2 levels to rise and cause a desreased LOC leading to a condition called CO2 narcosis.Hypoventilation Treatment | Hypoventilation Syndrome

All medscape requires registraiton but it is free and holds a TON of information.

I hope this helps and your book was right.......:)

Esme12, ASN, BSN, RN · Mar 19, 2012

It's backwards.

Hey Scott...read the question again. :)

NightNurseRN13 · Mar 19, 2012

Okay soooo.....

Low PaCO2 levels stimulate you to hypoventilate which compensates and ends up increasing CO2 levels

High PaCO2 levels stimulate you to hyperventilate which compensates and ends up decreasing CO2 levels

??? right?

Esme12, ASN, BSN, RN · Mar 19, 2012

low pco2 levels are a by product due to another source whether it is metabolic acidosis, as in the setting of diabetic ketoacidosis, to help off set the acidosis by hyperventilating to produce bicarbonate (very simply put) to compensate for the acidosis or in the setting someone is hyperventilating from anxiety groping the pco2 levels and ph causing a alkaloid state causing vasodilation dropping of ca+ levels causing numbness of the hands and face and muscle spasms. low pco2 levels don't have a hypoventilation stimuli to drop them as does elevated pco2 level stimulate you to breathe. the treatment of the underlying causative factor prevails here. low pco2 levels don't necessarily "cause" you to hypoventilate.

high pco2 levels stimulate you to breathe except in the presence of copd and co2 retainers. elevated pco2 will stimulate and increased respiratory drive to "blow off" the excess pco2 to normal levels not necessarily "hyperventilate"

you really should register for the medscape on the links i provided. it is free and is an excellent reference and informational site........what i have linked for you will, i think, clarify this confusion for you.

this may help as well...... https://allnurses.com/general-nursing-student/my-nursing-school-662475.html

ch 40 oxygenation.pdf‎

allnurses Guide · Mar 19, 2012

okay soooo.....
low paco2 levels stimulate you to hypoventilate which compensates and ends up increasing co2 levels
right, so you are retaining enough co2. this allows for production of carbonic acid. this is why you can end up with respiratory acidosis.
high paco2 levels stimulate you to hyperventilate which compensates and ends up decreasing co2 levels
right, so you are blowing off the co2. this decreases the production of carbonic acid. this is why you can end up with respiratory alkalosis.
??? right?

the drive to breathe is to get rid of co2. how ever much the body needs to retain or get rid of will determine the rate of ventilation to maintain balance.

i think that is the simplest way of thinking about it.

this is not taking into many many other factors that come into play, but strictly addresses the problem in your text.

GilaRRT · Mar 19, 2012

There exists a very important point that most people do not consider. Carbon dioxide by its self does not really effect breathing. Our primary stimulus to breath is not based on CO2 levels. In fact, pH change is our primary stimulus to breath. Central chemoreceptors in the brain monitor CSF pH and send this information to breathing centres in the brain.An example to illustrate this point is a DKA patient. They typically have very low CO2's, yet hyperventilate. A concerning dichotomy if we think CO2 is the primary stimulus to breath; however, it makes perfect sense from a pH context. Another example would include a COPD patient who has chronically elevated CO2 levels. We can look to a scarecrow explanation such as the hypoxic drive, or realise that chronic CO2 retention results in renal compensation and a relatively normal pH in spite of an elevated CO2. Again, it's all about the pH.