Hyperventilation and Emesis (Vomiting):
"Remember the case this Monday?", says Dr.J
"yes" I squeaked.
Last Monday, I appeared to be apprehensive in Dr. J's eyes, when I expressed my worries that patient had told me that she had a extreme case of a needle phobia.
ap·pre·hen·sive
/ˌapriˈhensiv/
Adjective
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Synonyms
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so back to today.
We had an unusually long surgery in one case... because of the 'red stuff'.
Later when I failed to have the patient follow my breathing instruction, Dr. J told me, "you have to coach" I observed as the Nurse waited for her to take her instruction.
"Remember we are professionals, so we have to take 'control' of the situation and lead the patient - do you know any parents controlled by their children? - it's a disaster. - we have to be the one reassuring patients."
said Dr.Johnson - as T came over and calmed the patient down and she went back to normal breathing --> less bleeding --> quicker surgery.
As patient was hyperventilating, he asked me a question.
"What happens when patient hyperventilate?".
And as always I fumbled...
[just like I did when we discussed the reason why Dr. J put pilocarpine in one eye that he was operating on:
"I couldn't find any reason based on her chart....aniscoriasis?".
"...you mean aniscoria?" -
Reason: Asian & hyperopia (aka farsightedness) - concluded from + A/R reading ("that's why A/R reading is important!) --> conclusion: smaller eye (shallow anterior chamber and narrow angle)--> leading to higher risk for Angle closure (Closed angle) glaucoma because a) smaller eye ...
"and bright light? so dilation...?"
"that causes constriction!"
"Right, SNS!!!"
"think local!"
"um (thinking alcane)...does it have Ach?" looks up at me
"no..."
"right! Epi!!" b) Epi in local anesthetic which will activate SNS and dilate pupils in addition to activation in a stressful situation --> Big pupils pushes down which means even more narrow angle - thus drop of pilo for prevention.]
"metabolic... no reproductive..not respiratory acidosis?"
"you have CO2 out, so that's alkalosis"
"I remember it being counter intuitive because of the bicarbonate (HCO3).... "
So moving on to next surgery, I couldn't let go and said,
"CO2 is going down so H2CO3 is converted to HCO3 + H+ so acidity goes up?"
and now I see that I was completely wrong!!!! how embarrassing!!!
Hyperventilation --> CO2 level decrease in blood (hypocapnia) - CO2 is carried as bicarbonate (CO2 = HCO3) (!!!!!!!) in the blood, so the loss of CO2 drives HCO3 + H+ --> Carbonic acid (H2CO3) --> H20 + CO2!! resulting loss of H+ makes blood alkaline and thus causes Metabolic Alkalosis
CO2 (g) + H20 (l) <=> H2CO3 (aq) <=> H+ (aq) + HCO3- (aq)CO2 goes down, H+ goes down fyi: it's moving <--
in other words...
it means:
fyi:
Respiratory acidosis is a condition that occurs when the lungs cannot remove all of the carbon dioxide the body produces. This causes body fluids, especially the blood, to become too acidic.
Metabolic acidosis is a condition in which there is too much acid in the body fluids.
- Diabetic acidosis (also called diabetic ketoacidosis and DKA) develops when substances known as ketone bodies, which are acidic, build up during uncontrolled type 1 diabetes
- Hyperchloremic acidosis results from excessive loss of sodium bicarbonate from the body, as can happen with severe diarrhea
- Lactic acidosis is a buildup of lactic acid. It can be caused by:
- Alcohol
- Cancer
- Exercising for a very long time
- Liver failure
- Low blood sugar (hypoglycemia)
- Medications such as salicylates
- Prolonged lack of oxygen from shock, heart failure, or severe anemia
Other causes of metabolic acidosis include:
- Kidney disease (distal tubular acidosis and proximal renal tubular acidosis)
- Poisoning by aspirin, ethylene glycol (found in antifreeze), or methanol
- Severe dehydration
Clinical implication of hyperventilation:
- lowers Intra Cranial Pressure
- Hyperventilation --> CO2 decreases --> Alkalosis --> Normally, alkalosis lowers neuronal excitability (pH: 7.4 → 7.8). Alkalosis causes H+ to move out from the cells and K+ to move in to the cell, leading to hypokalemia. This leads to a higher concentration gradient between intracellular and extracellular K+ leading to more K+ exiting the cell through leakage channels leading to hyperpolarization of the cell. This means that a greater than normal stimulus is required to reach the threshold and thus elicit a subsequent action potential.
- A major effect of alkalosis is hyperexcitability of the nervous system. Peripheral nerves are affected first, resulting in spontaneous nervous stimulation of muscles. Spasms and tetanic contractions and possibly extreme nervousness or convulsions result. Severe alkalosis can cause death as a result of tetany of the respiratory muscles
- Muscle contraction: hypocapnia causes muscular tension, poor posture, aggression and violence.
synthesis of glutamine:
“Studies designed to determine the effects produced by hyperventilation on nerve and muscle have been consistent in their finding on increased irritability” (Brown, 1953). Muscles and nerve cells become abnormally sensitive or irritated.
"Cortical CO2 tension and neuronal excitability". It was shown that CO2 has a strong calming effect on excessive excitability of brain areas responsible for thinking (Krnjevic et al, 1965).
hyperventilation "leads to spontaneous and asynchronous firing of cortical neurons"(Huttunen et. al, 1999).
= pain and bleeding?????
*
In other cases, there was emesis during surgery involving thyroid patient. (See Thyroid here!)
How can mere eye surgery cause emesis? Vagus nerve activation.
- Color of vomit
- Bright red in the vomit suggests bleeding from the esophagus
- Dark red vomit with liver-like clots suggests profuse bleeding in the stomach, such as from a perforated ulcer
- Coffee ground-like vomit suggests less severe bleeding in the stomach, because the gastric acid has had time to change the composition of the blood
- Yellow vomit suggests bile. This indicates that the pyloric valve is open and bile is flowing into the stomach from the duodenum. (This is more common in older people.)
Pressing upon certain places on the throat, sinuses, and eyes (also known as vagal reflex stimulation when performed clinically)
*
And I just remembered something about CABG (coronary artery bypass graft)...
heart bypass or bypass surgery is a surgical procedure performed to relieve angina and reduce the risk of death from coronary artery disease. Arteries or veins from elsewhere in the patient's body are grafted to the coronary arteries to bypass atheroscleroticnarrowings and improve the bloodsupply to the coronary circulationsupplying the myocardium (heart muscle). This surgery is usually performed with the heart stopped, necessitating the usage ofcardiopulmonary bypass; techniques are available to perform CABG on a beating heart, so-called "off-pump" surgery.
The terms single bypass, double bypass, triple bypass, quadruple bypass and quintuple bypass refer to the number of coronary arteries bypassed in the procedure. In other words, a double bypass means two coronary arteries are bypassed (e.g. the left anterior descending (LAD) coronary artery andright coronary artery (RCA)); a triple bypass means three vessels are bypassed (e.g. LAD, RCA, left circumflex artery (LCX)); a quadruple bypass means four vessels are bypassed (e.g. LAD, RCA, LCX, first diagonal artery of the LAD) while quintuple means five. Bypass of more than four coronary arteries is uncommon.
A greater number of bypasses does not imply a person is "more sick", nor does a lesser number imply a person is "healthier."[17] A person with a large amount of coronary artery disease (CAD) may receive fewer bypass grafts owing to the lack of suitable "target" vessels.
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