Do pulses correlate well with Blood Pressure (BP)?

Do Pulses Correlate Well with Blood Pressure?

Pulse pressure (the difference between systolic and diastolic BP) has limited correlation with overall blood pressure and should not be used as a substitute for direct BP measurement, though it provides additional prognostic information in specific populations, particularly elderly patients with systolic hypertension. 1

Understanding Pulse Pressure vs. Blood Pressure

What Pulse Pressure Represents

• Pulse pressure (PP) is calculated as systolic BP minus diastolic BP and reflects the interaction between left ventricular ejection (stroke volume) and arterial stiffness 2
• PP is a derived measure that combines the imperfections of both systolic and diastolic measurements, making it inherently less reliable than the original BP components 1
• In young and healthy individuals, central (aortic) pulse pressure differs substantially from peripheral (brachial) pulse pressure due to arterial compliance and wave reflection patterns 3

Limited Predictive Value in General Populations

• In the largest meta-analysis of 61 studies involving nearly 1 million subjects (70% European), pulse pressure was less predictive of cardiovascular outcomes than both systolic and diastolic blood pressures independently 1
• Both systolic and diastolic BP were independently and similarly predictive of stroke and coronary mortality, while PP contribution was small, particularly in individuals under 55 years 1
• The steady component of BP (mean arterial pressure) is a stronger risk factor for cardiovascular death in both sexes compared to the pulsatile component 4

When Pulse Pressure Does Provide Value

Elderly Patients with Isolated Systolic Hypertension

• Pulse pressure may be used to identify elderly patients with systolic hypertension who are at particularly high risk 1
• In middle-aged and elderly hypertensive patients with cardiovascular risk factors or associated clinical conditions, PP showed strong predictive value for cardiovascular events 1
• Wide pulse pressure in elderly patients with isolated systolic hypertension indicates pronounced increase in large artery stiffness and advanced organ damage 1
• The predictive contribution of pulse pressure increases after age 55 years 1

Dialysis Patients

• In dialysis patients, increased PP has been associated with increased all-cause mortality in nondiabetic hemodialysis patients 1
• Pre- and post-dialysis blood pressures have independent associations with mortality in a manner that implicates wide pulse pressures 1
• Each 10 mm Hg increase in pulse pressure was associated with an 8% increase in relative risk for all-cause mortality in non-diabetic dialysis patients 1

Clinical Practice Implications

BP Classification Should Use Systolic and Diastolic Values

• Classification of hypertension and risk assessment should continue to be based on systolic and diastolic blood pressures, not pulse pressure 1
• This is definitively the case for decisions concerning BP threshold and treatment goals, as these were the criteria employed in randomized controlled trials 1
• No practical cutoff values separating pulse pressure normality from abnormality at different ages have been established, despite suggestions of 50 or 55 mmHg 1

Measurement Accuracy Concerns

• Ambulatory BP monitoring readings may not be accurate when cardiac rhythm is markedly irregular, which would similarly affect pulse pressure calculations 1
• Standardized office BP measurements correlate better with out-of-office BP and end-organ damage than routine office BP 1
• Office BP readings are often significantly higher than standardized BP measurements (average difference of 20 mm Hg due to white-coat effect) 1

Important Caveats

• Pulse pressure is "floating" with no relation to absolute BP level, making it an unreliable standalone parameter 5
• PP has alterability in the same individual, limiting its consistency as a monitoring tool 5
• Central pulse pressure, which accounts for arterial compliance differences between peripheral arteries and the aorta, is more precise than brachial pulse pressure but is not routinely measured in clinical practice 1, 3
• Coronary perfusion occurs predominantly during diastole, making diastolic BP (not pulse pressure) the primary determinant of coronary perfusion pressure 6
• In elderly patients with isolated systolic hypertension, wide pulse pressure due to increased aortic stiffness leads to decreased diastolic BP (potentially compromising coronary perfusion) while high systolic pressure increases myocardial oxygen demand 6