Page 251 - Cardiac Nursing

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C HAPTER 1 0 / History Taking and Physical Examination 227
further assessment of the patient’s cardiovascular status may be
An unrecognized auscultatory gap may lead to serious indicated.
underestimation of systolic pressure (e.g., 150/98 in the
example below) or overestimation of diastolic pressure.
Measurement of Postural Blood Pressure
Postural (orthostatic) hypotension occurs when the blood pressure
Systolic
200 pressure drops after an upright posture is assumed. It usually is accompa-
nied by dizziness, lightheadedness, or syncope. Although there are
160 } Auscultatory gap many causes of postural hypotension, the three most commonly
seen in the cardiac patient are (1) intravascular volume depletion,
which often results from aggressive diuretic therapy, inadequate
mm Hg 120 Diastolic intake, or intravascular to extravascular fluid shift; (2) inadequate
vasoconstrictor mechanisms, which may be a primary pathologic
80 pressure process but also result from immobility; and (3) autonomic insuf-
ficiency, which is often related to the sympathetic blocking drugs
used in the cardiac patient. Postural changes in blood pressure,
40
along with the appropriate history, can help the clinician differ-
entiate between them. 25,26 Postural changes in blood pressure and
0 pulse should be measured in patients who are older than 65 years
of age, diabetic, receiving antihypertensive therapy, or who com-
If you find an auscultatory gap, record your findings
completely (e.g., 200/98 with an auscultatory gap plain of dizziness or syncope. Important points to remember are
from 170-150). the following:
■ Position the patient supine and as flat as symptoms permit for
■ Figure 10-13 Auscultatory gap. 10 minutes before the initial measurement of blood pressure
and heart rate.
■ Always check supine measurements before upright measure-
ments.
■ Always record both heart rate and blood pressure at each pos-
It is particularly common in patients with high blood pressure, tural change.
venous distention, or reduced velocity of arterial flow (e.g., severe ■ Do not remove the blood pressure cuff between position
18
aortic stenosis). The auscultatory gap can be as wide as 40 mm changes, but do check to see that it remains placed correctly.
Hg. Serious errors in blood pressure measurement can be made if
■ Safety considerations may require assessment of blood pres-
the cuff is not inflated high enough to exceed true systolic pres- sure and pulse with the patient seated with legs in the de-
sure. Systolic blood pressure would be underestimated if the sec- pendent position before standing. Measurement of blood
ond appearance of the Korotkoff sounds were recorded as phase I. pressure and pulse in this position is not sufficient to rule out
Diastolic blood pressure would be overestimated if the first muf- orthostasis. 26
fling of sounds was considered to be phase IV. The auscultatory
■ Have the patient assume a standing position. Measure the
gap can be avoided if a preliminary palpable blood pressure is ob- blood pressure and pulse immediately and after 2 minutes. If
tained before auscultation.
orthostasis is strongly suspected and not apparent after 2 min-
utes, continue to monitor blood pressure and pulse every
Measurement of Pulse Pressure 2 minutes for 10 minutes. If the purpose of collecting the data
Pulse pressure is the difference between the systolic and diastolic is to assess the risk of falling, another approach is to ask the pa-
blood pressures, expressed in millimeters of mercury. For example, tient to get out of bed as he or she normally does and evaluate
if the blood pressure is 120/80 mm Hg, the pulse pressure is the change in pulse rate and blood pressure and associated
40 mm Hg. Pulse pressure reflects stroke volume, ejection velocity, symptoms at the patient’s rate of position change.
and systemic vascular resistance. Use pulse pressure as a noninva-
■ Be alert for any signs or symptoms of patient distress, including
sive indicator of the patient’s ability to maintain cardiac output. dizziness, weakness, blurring of vision, and syncope. When the
Pulse pressure is increased in many situations. A widened pulse patient returns to a recumbent position, these symptoms should
pressure is seen in sinus bradycardia, complete heart block, aortic reverse and the blood pressure and pulse return to normal.
regurgitation, anxiety, exercise, and catecholamine infusion,
■ Record any signs or symptoms that accompany the postural
which are examples of situations characterized by increased stroke change.
volume. Examples of conditions that increase pulse pressure by re-
ducing systemic vascular resistance are fever, hot environment, Normal postural responses are a transient increased heart rate
and exercise. Conditions such as atherosclerosis, aging, and high of 5 to 20 beats per minute (to offset reduced stroke volume and
blood pressure widen the pulse pressure because of decreased dis- to maintain cardiac output), a drop in systolic pressure of less than
tensibility of the aorta, arteries, and arterioles. A narrowed pulse 10 mm Hg, and an increase in diastolic pressure of approximately
pressure also can be caused by many factors: reduced ejection ve- 5 mm Hg. Orthostasis is defined as a drop in systolic pressure of
locity in heart failure, shock, and hypovolemia; mechanical ob- 20 mm Hg or greater or a drop in diastolic pressure of at least
struction to systolic outflow in aortic stenosis, mitral stenosis, and 10 mm Hg within 3 minutes of standing, 26 although any drop in
mitral insufficiency; peripheral vasoconstriction in shock and with diastolic pressure may be cause for concern. The change from ly-
certain drugs; and artifactually from an auscultatory gap. 6,18 If the ing to sitting position is not sufficient to make a diagnosis of or-
pulse pressure in the cardiac patient falls below 30 mm Hg, thostasis; it may be used as a screening test because decreased