Download LWW PPT Slide Template Master

Chapter 23
Disorders of Blood Pressure
Regulation
Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins
Arterial Blood Pressure (Definitions)
• Systolic pressure: pressure at the height of the
pressure pulse
• Diastolic pressure: the lowest pressure
• Pulse pressure: the difference between systolic and
diastolic pressure
• Mean arterial pressure: represents the average
pressure in the arterial system during ventricular
contraction and relaxation
Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins
Arterial Blood Pressure
• Represents the pressure of the blood as it moves through
the arterial system
• Cardiac output = HR x SV
• Vascular resistance
• Mean arterial pressure = CO x VR
Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins
Mechanisms of Blood Pressure Regulation
• Short-term regulation: corrects temporary imbalances
in blood pressure
– Neural mechanisms
– Humoral mechanisms
• Long-term regulation: controls the daily, weekly, and
monthly regulation of blood pressure
– Renal mechanism
Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins
Factors Determining Systolic and Diastolic
Blood Pressure
• Systolic pressure
– The characteristics of the stroke volume being ejected
from the heart
– The ability of the aorta to stretch and accommodate the
stroke volume
• Diastolic pressure
– The energy that is stored in the aorta as its elastic fibres
are stretched during systole
– The resistance to the runoff of blood from the systemic
blood vessels
Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins
Korotkoff Sounds
• Phase I: marked by the first tapping sound, which
gradually increase in intensity
• Phase II: Period in which a murmur or swishing sound is
heard
• Phase III: Period during which sounds are crisper and
greater in intensity
• Phase IV: Period marked by distinct abrupt muffling or
by a soft blowing sound
• Phase V: Point at which sounds disappear
Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins
Factors Influencing Mean Arterial Blood
Pressure
• Physical
– Blood volume and the elastic properties of the blood
vessels
• Physiologic factors
– Cardiac output
– Systemic vascular resistance
Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins
Question
Which of the following does not directly affect arterial blood
pressure?
a. Heart rate
b. Vascular resistance
c. Venous constriction
d. Blood volume
Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins
Answer
c. Venous constriction
Rationale: Venous constriction will not affect arterial
pressure, whereas the other factors will have immediate
effects.
Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins
The Canadian Hypertension Education Program
(CHEP) and Canadian Blood Pressure
Recommendations
• Modifiable and nonmodifiable risk factors
– Nonmodifiable risk factors
• Family history, gender, race, and age-related
increases in blood pressure
– Modifiable risk factors
• Sedentary lifestyle, poor dietary habits, abdominal
obesity, impaired glucose tolerance or diabetes
mellitus, smoking, dyslipidemia, drug use, and
stress
Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins
Factors Affecting Hypertension
• Age
– More common in younger men than younger women
– More common in the elderly
• Race
– The Ontario Survey of the prevalence and control of
hypertension
– More common in blacks and South Asians
• Socioeconomic group
– More common in lower socioeconomic group
Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins
Categories of Hypertension
• Primary hypertension (essential hypertension)
–
The chronic elevation in blood pressure that occurs without
evidence of other disease
• Secondary hypertension
–
The elevation of blood pressure that results from some other
disorder, such as kidney disease
• Malignant hypertension
–
An accelerated form of hypertension
• Systolic hypertension
–
Systolic pressure of 140 mm hg or greater and a diastolic
pressure of less than 90 mm hg
Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins
Classifications of Essential Hypertension
• Systolic/diastolic hypertension
– Both the systolic and diastolic pressures are elevated
• Diastolic hypertension
– The diastolic pressure is selectively elevated
• Systolic hypertension
– The systolic pressure is selectively elevated
Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins
Risk Factors for Hypertension
• Family history
• Age-related changes in blood pressure
• Race
• Insulin resistance and metabolic abnormalities
• Circadian variations
• Lifestyle factors
Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins
Lifestyle Factors Contributing to
Hypertension
• High salt intake
• Obesity
• Excess alcohol consumption
• Dietary intake of potassium, calcium, and magnesium
• Oral contraceptive drugs
• Stress
Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins
Target Organ Damage
• The heart
–
Hypertrophy
• Brain
–
Dementia and cognitive impairment
• Systemic vascular
–
Atherosclerosis
• Kidney
–
Nephrosclerosis
• Retinal complications
Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins
Drugs Used in the Treatment of
Hypertension
• Diuretics
• β-adrenergic–blocking drugs
• Angiotensin-converting enzyme (ACE) inhibitors
• Angiotensin II receptor blockers
• The calcium channel–blocking drugs
• Central α2-adrenergic agonists
• α1-adrenergic receptor blockers
• Vasodilators
Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins
Factors Affecting Treatment Strategies for
Hypertension
• Lifestyle
• Demographics
• Motivation for adhering to the drug regimen
• Other disease conditions and therapies
• Potential for side effects
Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins
Question
Renal failure results in Na+ and water retention. This
results in hypertension. How would you classify this type
of hypertension?
a. Primary hypertension
b. Secondary hypertension
c. Malignant hypertension
d. Systolic hypertension
Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins
Answer
b. Secondary hypertension
Rationale: Secondary hypertension is the result of an
underlying disease.
Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins
Most Common Causes of Secondary
Hypertension
• Kidney disease (renovascular hypertension)
• Adrenal cortical disorders
• Pheochromocytoma
• Coarctation of the aorta
• Sleep apnea
Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins
Types of Hypertension in Pregnancy
• Gestational hypertension
• Chronic hypertension
• Preeclampsia-eclampsia
• Preeclampsia superimposed on chronic hypertension
Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins
Diagnosis and Treatment of Hypertension
in Pregnancy
• Early prenatal care
• Refraining from alcohol and tobacco use
• Salt restriction
• Bed rest
• Carefully chosen antihypertensive medications
Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins
High Blood Pressure in Children and
Adolescents
• Blood pressure norms for children are based on age, height,
and gender-specific percentiles
• Secondary hypertension is the most common form of high
blood pressure in infants and children
– Kidney abnormalities
– Coarctation of the aorta
– Pheochromocytoma and adrenal cortical disorders
• In infants, associated most commonly with high umbilical
catheterization and renal artery obstruction caused by
thrombosis
Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins
Orthostatic Hypotension
• Definition
– An abnormal decrease in blood pressure on
assumption of the upright position
• Causes
– Decrease in venous return to the heart due to
pooling of blood in lower part of body
– Inadequate circulatory response to decreased cardiac
output and a decrease in blood pressure
Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins
Causes of Orthostatic Hypotension
• Conditions that decrease vascular volume
– Dehydration
• Conditions that impair muscle pump function
– Bed rest
– Spinal cord injury
Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins
Causes of Orthostatic Hypotension (cont.)
• Conditions that interfere with cardiovascular
reflexes
– Medications
– Disorders of autonomic nervous system
– Effects of aging on baroreflex function
Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins
Common Causes of Orthostatic
Hypotension Related to Hypovolemia
• Excessive use of diuretics
• Excessive diaphoresis
• Loss of gastrointestinal fluids through vomiting and
diarrhea
• Loss of fluid volume associated with prolonged bed rest
Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins
Complaints Associated With Orthostatic
Intolerance
• Dizziness
• Visual changes
• Head and neck discomfort
• Poor concentration while standing
• Palpitations
• Tremor, anxiety
• Presyncope, and in some cases syncope
Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins
Question
Increased vascular compliance may contribute to which
condition?
a. Systolic hypertension
b. Orthostatic hypotension
c. Orthostatic hypertension
d. Diastolic hypertension
Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins
Answer
b. Orthostatic hypotension
Rationale: Orthostatic hypotension is the result of lower
pressures, and increased compliance would decrease
the vascular resistance and result in lower pressures.
Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins