Acid-Base Balance pt 1

What does blood pH measure?

The acidity or alkalinity of the blood

Blood pH is a measure of which ions in the blood?

Free hydrogen ions (H⁺)

An increase in hydrogen ions (H⁺) will cause which condition?

Acidosis, a decrease in blood pH.

What is the normal range for arterial blood pH?

7.35–7.45

A blood pH of 7.30 indicates which acid–base imbalance?

Acidosis, a state of increased acidity in the blood.

A blood pH of 7.48 indicates which acid–base imbalance?

Alkalosis, a state of increased alkalinity in the blood.

Why are small changes in blood pH dangerous?

They can affect vital body systems such as the lungs, heart, and brain

Which body systems work together to regulate blood pH?

Respiratory and renal systems along with buffers

Which system provides the fastest response to pH changes?

Respiratory system

Which system provides long-term regulation of blood pH?

Renal system

How do cells help regulate acid–base balance?

By moving hydrogen ions (H⁺) in and out of the cells

Cellular buffering of hydrogen ions is best described as:

Fast and temporary

Which systems ultimately take over acid–base regulation after cellular buffering?

Lungs and kidneys

How do the lungs regulate acid levels in the body?

By adjusting the rate and depth of breathing

An increased respiratory rate has what effect on carbon dioxide (CO₂)?

It decreases CO₂ levels in the blood.

Decreasing the respiratory rate causes what change in CO₂ levels?

It increases CO₂ levels in the blood.

Carbon dioxide (CO₂) is considered what in acid–base balance?

An acid

Which organ system provides the fastest regulation of acid–base balance?

Lungs

How do the kidneys regulate acid–base balance?

By using bicarbonate (HCO₃⁻)

Bicarbonate (HCO₃⁻) is classified as what?

A base (buffer)

Compared to the lungs, kidney regulation of acid–base balance is:

Slow

Which system provides long-term control of acid–base balance?

Kidneys

Carbon dioxide (CO₂) combined with water forms what acid in the body?

Carbonic acid (H₂CO₃)

Carbonic acid is classified as what in acid–base balance?

An acid

How do the lungs regulate blood pH?

By controlling blood levels of carbon dioxide (CO₂) through ventilation

Changes in CO₂ levels directly affect which ions in the blood?

Hydrogen ions (H⁺)

What happens to acid levels when a patient breathes faster or deeper?

Acid levels decrease

What is the acid–base effect of slow or shallow breathing?

O₂ is retained, increasing acid levels

Retention of CO₂ leads to what change in blood pH?

Decreased pH (acidosis)

Which acid–base imbalance is associated with hypoventilation?

Respiratory acidosis

How quickly do the lungs respond to changes in acid–base balance?

Within minutes

Which side of acid–base balance do the kidneys primarily regulate?

Metabolic (non-respiratory) side

How do the kidneys directly remove acid from the body?

By excreting hydrogen ions (H⁺) in the urine

The kidneys regulate acid–base balance by doing which of the following?

Excreting acid and excreting or retaining bicarbonate

Retaining bicarbonate has what effect on blood pH?

Increases pH (more alkaline)

Excreting bicarbonate has what effect on blood pH?

Decreases pH (more acidic)

An increased hydrogen ion (H⁺) concentration results in what pH change?

Decreased pH (acidic)

A decreased hydrogen ion (H⁺) concentration results in what pH change?

Increased pH (alkaline)

What lab test is used to interpret acid–base balance?

Arterial Blood Gas (ABG)

Why are ABGs used to assess acid–base status?

They measure blood pH and components that affect acid–base balance

From where is an ABG sample most commonly drawn?

Radial artery

Why must ABG samples be drawn from an artery instead of a vein?

Arterial blood reflects oxygenation and acid–base status more accurately

Which ABG value indicates the overall acid–base status of the blood?

pH

Which ABG value reflects the respiratory component of acid–base balance?

PaCO₂

Which ABG value reflects the metabolic component of acid–base balance?

HCO₃⁻ (bicarbonate)

Which ABG value measures the partial pressure of oxygen in arterial blood?

PaO₂

Which ABG value reflects the percentage of hemoglobin saturated with oxygen?

SaO₂ (or SpO₂)

Which ABG values are primarily used to determine acid–base imbalances?

pH, PaCO₂, and HCO₃⁻

Which ABG values assess oxygenation rather than acid–base balance?

PaO₂ and SaO₂/SpO₂

Which body system regulates PaCO₂?

Respiratory system (lungs)

Changes in which respiratory factors affect PaCO₂ levels?

Rate and depth of respirations

What is the normal PaCO₂ range?

35–45 mmHg

PaCO₂ values reflect which body system?

Respiratory system

What is the normal bicarbonate (HCO₃⁻) range?

22–26 mEq/L

HCO₃⁻ values reflect which body system?

Renal (metabolic) system

What is the normal PaO₂ range?

80–100 mmHg

PaO₂ measures what?

Oxygen available to bind to hemoglobin’

• The amount of oxygen dissolved in arterial blood

What is the normal SaO₂ range?

95–100%

SaO₂ represents what?

Percentage of hemoglobin saturated with oxygen

Which ABG values assess oxygenation rather than acid–base balance?

PaO₂ and SaO

An elevated PaCO₂ indicates what about ventilation?

Inadequate ventilation (hypoventilation)

High PaCO₂ has what effect on acid–base balance?

Increased acid → respiratory acidosis

A low HCO₃⁻ level indicates which acid–base imbalance?

Metabolic acidosis (< 22 mEq/L)

A high HCO₃⁻ level indicates which acid–base imbalance?

Metabolic alkalosis (> 26 mEq/L)

When is pulse oximetry considered accurate?

When O₂ saturation is above 80%

What should be done if O₂ saturation is below 80%?

ABG analysis is recommended

Which value is more precise for low oxygen levels: PaO₂ or SpO₂?

PaO₂ (from ABG)

What is mild hypoxemia based on PaO₂?

60–79 mmHg

What is moderate hypoxemia based on PaO₂?

40–59 mmHg

What is severe hypoxemia based on PaO₂?

0–39 mmHg

What is the first step when interpreting an ABG?

Look at the pH to determine if it’s normal (7.35–7.45), acidotic (<7.35), or alkalotic (>7.45)