Understanding Blood Pressure and Oxygen Saturation

Blood Pressure

• Blood pressure is the force exerted on the walls of an artery by the pulsing blood under pressure from the heart.
• Blood flow throughout the circulatory system, moving from an area of high to an area of low pressure.
• Systematic or arterial blood pressure is a good indicator of cardiovascular health.

Components of Blood Pressure

• Systolic blood pressure: the peak maximum pressure when the heart ventricles contract.
• Diastolic blood pressure: the pressure when the heart ventricles relax.
• Pulse pressure: the difference between systolic and diastolic pressure.

Physiology of Arterial Blood Pressure

• Blood pressure reflects the interrelationships of cardiac output, peripheral vascular resistance, blood volume, blood viscosity, and artery elasticity.
• Hemodynamic variables:
  • Cardiac output: increases blood pressure as it increases.
  • Peripheral vascular resistance: increases blood pressure as it increases.
  • Blood volume: increases blood pressure as it increases.
  • Blood viscosity: increases blood pressure as it increases.
  • Artery elasticity: decreases blood pressure as it decreases.

Factors Influencing Blood Pressure

• Age:
  • Blood pressure increases during childhood.
  • Blood pressure tends to increase with advancing age.
• Stress:
  • Emotional stress increases heart rate, cardiac output, blood pressure, and peripheral vascular resistance.
• Gender:
  • Males tend to have higher blood pressure after puberty.
  • Females are at increased risk for hypertension due to changes like pregnancy, birth control, and menopause.
• Daily variation:
  • Blood pressure increases in the morning, peaks in the late afternoon, and decreases at night.
• Medications:
  • Certain medications can affect blood pressure.
• Activity, weight, and smoking:
  • Blood pressure can be reduced for several hours after exercise.
  • Obesity is a factor in hypertension.
  • Blood pressure rises when smoking and returns to baseline 15 minutes after smoking ceases.

Hypertension

• Defined as a blood pressure of 140/90 mmHg or higher.
• Often asymptomatic.
• Associated with thickening and loss of elasticity in the arterial walls.
• Diagnosed using criteria:
  • Mean blood pressure obtained by office blood pressure measurement or automated office blood pressure.
  • First reading of systolic blood pressure measured by automated office blood pressure.
  • Systolic blood pressure measured by office blood pressure measurement.

Hypotension

• Defined as a systolic blood pressure of 90 mmHg or lower.
• Occurs due to the dilation of arteries, loss of blood volume, or failure of the heart muscle to pump adequately.
• Associated with pallor, skin mottling, clamminess, confusion, increased heart rate, or decreased urine output.

Measuring Blood Pressure

• Can be measured directly (invasively) or indirectly (noninvasively).
• Indirect measurement:
  • Uses a sphygmomanometer and stethoscope.
  • Cuff should be proportional to the circumference of the limb being assessed.
  • Lower edge of the cuff should be positioned 3 cm above the antecubital fossa.

Oscillometric and Auscultation Methods

• Oscillometric method:
  • Uses a sphygmomanometer and electronic device to detect blood pressure.
  • Preferred over auscultation method.
• Auscultation method:
  • Uses a stethoscope to detect Korotkoff sounds.
  • Best environment for measurement is a quiet room at a comfortable temperature.

Orthostatic Hypotension

• Defined as a drop in blood pressure when standing up from a sitting or lying down position.
• Caused by the dilation of arteries in the vascular bed, loss of blood volume, or failure of the heart muscle to pump adequately.
• Associated with pallor, skin mottling, clamminess, confusion, increased heart rate, or decreased urine output.

Blood Pressure in Children

• Changes with growth and development.
• Measurement of blood pressure in infants and children is difficult due to:
  • Difficulty in obtaining cooperation.
  • Placing the stethoscope too firmly on the antecubital fossa.
  • Korotkoff sounds are difficult to hear in children.

Nursing Process and Vital Signs

• Assessing blood pressure and pulse evaluates the patient's general state of cardiovascular health and responses to other system imbalances.
• Hypotension, hypertension, orthostatic hypotension, and narrow or wide pulse pressures are defining characteristics of certain nursing diagnoses.

Blood Pressure

• Blood pressure is the force exerted on the walls of an artery by the pulsing blood under pressure from the heart.
• Blood flow throughout the circulatory system, moving from an area of high to an area of low pressure.
• Systematic or arterial blood pressure is a good indicator of cardiovascular health.

Components of Blood Pressure

• Systolic blood pressure: the peak maximum pressure when the heart ventricles contract.
• Diastolic blood pressure: the pressure when the heart ventricles relax.
• Pulse pressure: the difference between systolic and diastolic pressure.

Physiology of Arterial Blood Pressure

• Blood pressure reflects the interrelationships of cardiac output, peripheral vascular resistance, blood volume, blood viscosity, and artery elasticity.
• Hemodynamic variables:
  • Cardiac output: increases blood pressure as it increases.
  • Peripheral vascular resistance: increases blood pressure as it increases.
  • Blood volume: increases blood pressure as it increases.
  • Blood viscosity: increases blood pressure as it increases.
  • Artery elasticity: decreases blood pressure as it decreases.

Factors Influencing Blood Pressure

• Age:
  • Blood pressure increases during childhood.
  • Blood pressure tends to increase with advancing age.
• Stress:
  • Emotional stress increases heart rate, cardiac output, blood pressure, and peripheral vascular resistance.
• Gender:
  • Males tend to have higher blood pressure after puberty.
  • Females are at increased risk for hypertension due to changes like pregnancy, birth control, and menopause.
• Daily variation:
  • Blood pressure increases in the morning, peaks in the late afternoon, and decreases at night.
• Medications:
  • Certain medications can affect blood pressure.
• Activity, weight, and smoking:
  • Blood pressure can be reduced for several hours after exercise.
  • Obesity is a factor in hypertension.
  • Blood pressure rises when smoking and returns to baseline 15 minutes after smoking ceases.

Hypertension

• Defined as a blood pressure of 140/90 mmHg or higher.
• Often asymptomatic.
• Associated with thickening and loss of elasticity in the arterial walls.
• Diagnosed using criteria:
  • Mean blood pressure obtained by office blood pressure measurement or automated office blood pressure.
  • First reading of systolic blood pressure measured by automated office blood pressure.
  • Systolic blood pressure measured by office blood pressure measurement.

Hypotension

• Defined as a systolic blood pressure of 90 mmHg or lower.
• Occurs due to the dilation of arteries, loss of blood volume, or failure of the heart muscle to pump adequately.
• Associated with pallor, skin mottling, clamminess, confusion, increased heart rate, or decreased urine output.

Measuring Blood Pressure

• Can be measured directly (invasively) or indirectly (noninvasively).
• Indirect measurement:
  • Uses a sphygmomanometer and stethoscope.
  • Cuff should be proportional to the circumference of the limb being assessed.
  • Lower edge of the cuff should be positioned 3 cm above the antecubital fossa.

Oscillometric and Auscultation Methods

• Oscillometric method:
  • Uses a sphygmomanometer and electronic device to detect blood pressure.
  • Preferred over auscultation method.
• Auscultation method:
  • Uses a stethoscope to detect Korotkoff sounds.
  • Best environment for measurement is a quiet room at a comfortable temperature.

Orthostatic Hypotension

• Defined as a drop in blood pressure when standing up from a sitting or lying down position.
• Caused by the dilation of arteries in the vascular bed, loss of blood volume, or failure of the heart muscle to pump adequately.
• Associated with pallor, skin mottling, clamminess, confusion, increased heart rate, or decreased urine output.

Blood Pressure in Children

• Changes with growth and development.
• Measurement of blood pressure in infants and children is difficult due to:
  • Difficulty in obtaining cooperation.
  • Placing the stethoscope too firmly on the antecubital fossa.
  • Korotkoff sounds are difficult to hear in children.

Nursing Process and Vital Signs

• Assessing blood pressure and pulse evaluates the patient's general state of cardiovascular health and responses to other system imbalances.
• Hypotension, hypertension, orthostatic hypotension, and narrow or wide pulse pressures are defining characteristics of certain nursing diagnoses.