Respiratory Therapy and Acid-Base Physiology Flashcards

Comprehensive practice flashcards covering respiratory physiology, acid-base balance, buffer systems, and clinical ABG procedures based on the lecture transcript.

Strong acids and bases

Substances that dissociate completely in a mixture and have trouble reforming into their original state.

Weak acids and bases

Substances that dissociate in a mixture but not completely, allowing them to reform and push equations in different directions.

Carbonic acid ($H_2CO_3$)

A weak, volatile acid formed in the middle portion of the $CO_2$ hydration reaction.

Bicarbonate ($HCO_3^-$)

An example of a weak base highlighted in the $CO_2$ hydration reaction.

Hydrogen Ion ($H^+$)

Considered a strong acid that dissociates from carbonic acid.

Systemic capillary circulation

The level at which $CO_2$ flows from tissues into the bloodstream following metabolism.

$CO_2$ hydration reaction

The chemical process where $CO_2 + H_2O \rightleftharpoons H_2CO_3 \rightleftharpoons HCO_3^- + H^+$.

Chemical buffer systems

The first line of defense in the body that responds the fastest to regulate acids and bases.

Phosphate buffer system

A chemical buffer system that is approximately one-sixth as effective as the carbonic acid system and operates primarily in the kidneys and intracellular fluid.

Glomerular filtrate

The initial product in the kidneys that eventually becomes urine and contains phosphates.

Protein buffer system

The third chemical buffer system found in plasma and cells, providing $75\%$ of the buffering power of body fluids.

Amphoteric molecules

Molecules that can function as either an acid or a base depending on the environment, such as proteins.

Hemoglobin

An amphoteric molecule that can bind with free hydrogen ions when reduced at the tissue level to decrease plasma acidity.

Respiratory system buffering

A regulation system with twice the buffering power of chemical systems, acting as a secondary defense.

Right shift

An equilibrium shift in the hydration reaction caused by an increase in $CO_2$ or hypoventilation.

Left shift

An equilibrium shift in the hydration reaction caused by hyperventilation or a reduction in $CO_2$.

Henderson-Hasselbalch equation

A conceptual mathematical equation used to determine normal pH based on pK and the ratio of bases to acids.

pK

A mathematical constant specific to a particular acid, such as carbonic acid, which does not change.

20 to 1

The normal ratio of bases to acids in the system required to maintain a pH of $7.4$.

15 to 1

A ratio of bases to acids that would cause the pH to become more acidic (less than $7.4$).

30 to 1

A ratio of bases to acids that would move the pH in a more alkaline direction (above $7.4$).

Eucapnia

A condition referring to a normal level of $CO_2$ in the system where $P_A CO_2$ and $P_a CO_2$ are essentially equal.

Hypercapnia

A clinical condition where the level of $P_a CO_2$ is elevated in the arterial blood.

Hypocapnia

A clinical condition where there is a reduction in $CO_2$ levels in the blood.

Hypoventilation

A decrease in minute ventilation accompanied by an elevated $P_a CO_2$ value.

Hyperventilation

An increase in ventilation that results in a lower $P_a CO_2$ value.

$$200\,mL/min$$

The amount of $CO_2$ produced at the tissue level under normal resting conditions.

Alveolar ventilation ($\dot{V}_A$)

A measure of ventilation, normally around $4\,L/min$ under resting conditions.

Minute ventilation variables

The two variables that create minute ventilation: respiratory rate and tidal volume.

Fixed acids

Acids removed from the body through the kidneys, including phosphoric acid, lactic acid, and ketones.

Renal system role

The system responsible for ridding the body of fixed acids and regulating alkaline substances like bicarbonate.

Acid-base disturbances

Conditions occurring when the three regulatory systems cannot adequately respond to sudden, large changes in acids or bases.

ABG analysis

Arterial Blood Gas analysis; the most basic test of lung function performed on an anaerobic sample of arterial blood.

Anaerobic sample

A blood sample that must be free of air bubbles to prevent the alteration of gas concentrations like $CO_2$.

Normal pH range

The healthy range for arterial blood pH, which is $7.35$ to $7.45$.

Physiologic pH range

The survival range of pH for a living patient, typically between $6.9$ and $7.8$.

Normal $P_a CO_2$ range

The standard range for arterial carbon dioxide, which is $35$ to $45\,mmHg$ (or torr).

Normal $P_a O_2$ range

The standard range for arterial oxygen tension, which is $80$ to $100\,mmHg$.

Mixed venous $P_v O_2$

The approximate oxygen tension in mixed venous blood, which is about $40\,mmHg$.

Mixed venous $P_v CO_2$

The approximate carbon dioxide tension in mixed venous blood, typically between $40$ and $46\,mmHg$.

A-a gradient

The difference between alveolar oxygen ($P_A O_2$) and arterial oxygen ($P_a O_2$), usually less than $20\,mmHg$ in healthy people.

Normal anatomical shunts

Physiologic mixing of venous blood with arterial blood through bronchial circulation and thebesian veins.

Fick's Law factors

Factors affecting diffusion: surface area, partial pressure gradient, and membrane thickness.

$V/Q$ mismatch

Ventilation-perfusion mismatch; a condition where ventilation and blood flow do not match, decreasing $P_a O_2$.

Arterial oxygen content ($C_a O_2$)

The total amount of oxygen in the blood, calculated as oxygen attached to hemoglobin plus oxygen dissolved in plasma.

$$1.34$$

The constant factor representing the milliliters of oxygen that can be carried by one gram of fully saturated hemoglobin.

Oxygen delivery factors

Dependent upon arterial oxygen content and cardiac output.

Bicarbonate units

Measured in milliequivalents per liter ($mEq/L$).

Normal Bicarbonate range

Typically $22$ to $26\,mEq/L$, or expressed as $24 \text{ plus or minus } 2$.

Base excess

An evaluation of all bases in the system, excluding just bicarbonate; normal range is $-2$ to $+2$.

Acute ventilatory failure

A sudden failure in ventilation leading to respiratory acidosis.

Chronic ventilatory failure

A condition seen in patients like those with severe emphysema who live at a higher $P_a CO_2$ level with complete renal compensation.

Respiratory alkalosis

A condition characterized by a high pH and low $P_a CO_2$ resulting from hyperventilation.

Metabolic acidosis

A condition caused by an accumulation of fixed acids or a loss of bicarbonate.

Metabolic alkalosis

A rare condition that can be caused by hypokalemia, hypochloremia, or gastric suctioning.

Lactic acidosis

Acidity resulting from anaerobic metabolism when oxygen needs of tissues are not met.

Ketoacidosis

Acidity resulting from low insulin levels, causing ketones to accumulate in the blood.

Salicylate intoxication

A metabolic acidosis caused by an aspirin overdose.

Uncontrolled diarrhea

A condition that results in the excessive loss of bicarbonate, leading to metabolic acidosis.

Anion gap

A calculation used to determine if metabolic acidosis is due to fixed acid accumulation or bicarbonate loss.

Law of electro-neutrality

The principle that the total number of cations must equal the number of anions in body fluids.

Anion Gap formula

$$[Na^+] - ([Cl^-] + [HCO_3^-])$$

Normal Anion Gap range

$9$ to $14\,mEq/L$.

High Anion Gap ($> 14$)

Indicative of the accumulation of fixed acids, such as in lactic acidosis or ketoacidosis.

Guillain-Barre syndrome

A neurologic disorder described as 'ground to the brain' that can impact the diaphragm and cause ventilatory failure.

Myasthenia gravis

A neurologic disorder described as 'mind to the ground' that can impact respiratory muscles.

Hypoxia

A condition where oxygen levels are reduced at the tissue level.

Hypoxemia

A condition where oxygen levels are reduced specifically in the blood.

Radial artery

The preferred site for ABG puncture located on the thumb side of the wrist.

Ulnar artery

The artery on the pinky side of the wrist that provides collateral circulation to the hand.

Collateral blood flow

The redundant blood supply to the hand from both the radial and ulnar arteries.

Modified Allen's test

A physical exam used to check for adequate collateral circulation before performing a radial artery puncture.

Positive Allen's test

Observation of hand flushing within $15$ seconds after releasing the ulnar artery, indicating safe puncture conditions.

Brachial artery site

A puncture site found medial to the antecubital fossa.

Femoral artery site

A puncture site located in the groin area, typically requiring the patient to lie flat.

Dorsalis pedis

An arterial puncture site located on the top of the foot.

Posterior tibial artery

A site found around the inside of the ankle, rarely used for ABG samples.

Umbilical artery

The site used for ABG sampling in neonates.

Warmed capillary sample

An alternative method of gas collection used in the neonate population.

Dialysis shunt

A surgical connection between a vein and an artery; ABGs should never be drawn distal to this.

PVD

Peripheral Vascular Disease; a contraindication for choosing a specific arterial puncture site.

Anticoagulant therapy

Medication that requires holding pressure for a longer duration after an arterial puncture to prevent hematomas.

Heparin pellet

A substance inside ABG syringes used to prevent the blood sample from clotting.

Lymphedema risk

The reason why ABGs are usually avoided on the same side as a patient's mastectomy.

Propofol

An anesthetic drug, sometimes called 'milk of amnesia,' that can cause ventilatory failure.

Hematoma

A localized swelling filled with blood that can occur if pressure is not held sufficiently after a puncture.

Sodium ($Na^+$)

The primary cation measured when calculating the anion gap.

Chloride ($Cl^-$)

A primary anion measured alongside bicarbonate for the anion gap calculation.

Anemia and Allen's Test

A condition that might make the flushing of the hand take longer during a modified Allen's test due to poor perfusion.

Volatile acid

An acid that can be converted into a gas and eliminated by the lungs, like carbonic acid.

Anaerobic metabolic byproduct

Lactic acid, which is produced when glucose is metabolized without sufficient oxygen.

First line of defense

The chemical buffer systems (bicarbonate, phosphate, and protein).

Blood plasma

The liquid portion of the blood, composed of over $90\%$ water, where the hydration reaction takes place.

pK of carbonic acid

A constant value used in the Henderson-Hasselbalch equation (noted as $6.1$ in mathematics, mentioned as 'a constant' in transcript).

Eucapnic condition

A state where the amount of $CO_2$ produced at the tissue equals the amount eliminated by the lungs.

Hypercapnia and hypoventilation

Physiological pair where low ventilation leads to high arterial carbon dioxide.

Hypocapnia and hyperventilation

Physiological pair where high ventilation leads to low arterial carbon dioxide.

Respiratory acidosis cause

Result of an increase in $CO_2$ causing a right shift in the hydration reaction.

Metabolic acidosis from diarrhea

Occurs specifically because of the loss of base ($HCO_3^-$) in the stool.

25 gauge needle

A common small-gauge needle used for performing arterial blood gas punctures.