Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
26 Cards in this Set
- Front
- Back
|
What is the range of normal pressures in each chamber of the heart?
|
Right atrium, 1-8 mmHg; right ventricle, 15-30/O-8 mmHg; left atrium, 2-12 mmHg; left ventricle, 100-140/O-12 mmHg. [Dunn, et al., Mass. Gen. 7e. 2007 pp402t]
|
|
|
What is the normal value for mean pulmonary artery pressure? For pulmonary artery systolic and diastolic pressures?
|
Mean pulmonary artery pressure normally is about 16 mmHg. Systolic/diastolic pressures average 25/8 mm Hg. [Guyton, TMP.11e. 2006 pp484]
|
|
|
What is the normal range of values for pulmonary artery occlusion pressure (PAOP), also called pulmonary capillary wedge pressure (PCWP)?
|
Normal PAOP = 5-15 mmHg. When stated as wedge pressure, PCWP = 2-12 mmHg. [Miller & Stoelting, Basics. 5e. 2007 pp53, 310; Morgan, et al., Clin. Anesth. 4e. 2006 ppl36f; Dunn, et al., Mass. Gen. 7e. 2007 pp402t]
|
|
|
What is the normal value for mean systemic arterial pressure?
|
Normal mean arterial pressure ranges from 80-120 mmHg. [Barash, Handbook. 5e. 2006 pp510, 972]
|
|
|
How do you estimate mean arterial pressure (MAP)?
|
Use the 1,2,3 rule. MAP = (1 x SBP + 2 x DBP)/3. Alternatively, MAP can be calculated as follows: MAP = DBP + (1/3) (pulse pressure) = DBP + (1/3) (SBP—DBP). Either equation gives the correct answer. Note: SBP = systolic blood pressure; DBP = diastolic blood pressure. [Morgan, et al., Clin. Anesth. 4e. 2006 pp429; Barash, Handbook. 5e. 2006 pp972]
|
|
|
If arterial blood pressure is 150/90, what is the mean arterial pressure (MAP)?
|
Using the 1, 2, 3 rule, MAP = [1 x 150 + (2 x 90)]/3 = [150 + 180]/3 = 330/3 = 110 mm Hg. The answer is the same if the alternate equation is used: MAP = 90 +(1/3) 60 = 90 + 20 = 110 mmHg. [Authors]
|
|
|
What causes a change in blood pressure when changing the patient's position?
|
Altered preload (altered venous return) is most responsible for a change in blood pressure when the patient is re-positioned. [Barash, Clin. A nes., 1997, pp595-597]
|
|
|
What are the two determinants of arterial blood pressure? What law applies?
|
The two determinants of systemic arterial blood pressure are systemic vascular resistance (SVR) and cardiac output (CO). This is an application of Ohm's law. [Barash, Clinical Anes. 5e. 2006 pp856, 878; Stoelting, PPAP. 4e. 2006 pp725]
|
|
|
What most determines systemic vascular resistance?
|
Systemic vascular resistance (SVR) is determined by the tone (degree of constriction) of arterioles and small arteries. [Guyton, TMP. lle. 2006 pp168; Morgan, et al., Clin. Anesth. 4e. 2006 pp424]
|
|
|
What is normal range of values for systemic vascular resistance (SVR)?
|
The normal range for SVR is 1200-1500 dynes.sec.cm5. [Barash, Handbook. 5e. 2006 pp510, 972; Miller, Anesthesia. 6e. 2005 pp1328t]
|
|
|
How do you calculate systemic vascular resistance (SVR)?
|
SVR = [(MAP-CVP)/C0] x 80, where MAP is mean arterial pressure, CVP is central venous pressure, and C0 is cardiac output. The units for SVR are dynes.sec.cm5. [Barash, Handbook. 5e. 2006 pp510, 972; Miller, Anesthesia. 6e. 2005 pp1328t]
|
|
|
If mean arterial pressure is 80 mmHg, cardiac output 9 liters/min, and central venous pressure 8 mmHg, calculate SVR
|
SVR = [(MAP-CVP)/C01x 80 = [(80-8)19] x 80 = 640 dynes.sec.cm5. [Authors]
|
|
|
In what segment of the systemic circulation is resistance greatest? The greatest decrease in blood pressure in the arterial tree occurs where?
|
The resistance to blood flow is greatest in the arterioles, accounting for about half the resistance in the entire systemic circulation. The greatest decrease in blood pressure in the arterial tree occurs in the arterioles. [Stoelting, PPAP. 4e. 2006 pp719-720; Guyton, TMP. lle. 2006 pp162— 163]
|
|
|
What maintains systemic arterial blood pressure during diastole?
|
Elastic recoil of arterial blood vessels during diastole keeps systemic arterial blood pressure from falling precipitously during diastole. [Guyton, TMP. 11e. 2006 pp109]
|
|
|
What is pulse pressure? The patient's arterial blood pressure is 160/90 mmHg: calculate the patient's pulse pressure.
|
Pulse pressure is the difference between the systolic and diastolic arterial pressures during the cardiac cycle. The patient with a blood pressure of 160/90 has a pulse pressure of 160 — 90 = 70 mmHg. [Guyton, TMP. 11e. 2006 pp173]
|
|
|
What are two determinants of pulse pressure? What changes can increase pulse pressure? Decrease pulse pressure?
|
The two determinants of pulse pressure are stroke volume and arterial compliance. Pulse pressure is determined by the ratio of stroke volume to arterial compliance. Pulse pressure increases when either cardiac output increases or arterial compliance decreases. Pulse pressure decreases when either cardiac output decreases or arterial compliance increases. [Guyton, TMP. lle. 2006 pp173-174]
|
|
|
Define compliance. When peripheral vessels become less compliant (as would occur in the patient with atherosclerosis), does pulse pressure increase or decrease?
|
Compliance is defined as a change in volume for a given change in pressure. When compliance of arterial vessels decreases, pulse pressure increases. [Guyton, TMP. lle. 2006 pp172-173[
|
|
|
Where are arterial baroreceptors located? To what do the baroreceptors respond?
|
Baroreceptors are located in the aortic arch and carotid sinus. The aortic and carotid baroreceptors respond to stretching caused by mean arterial pressure greater than 90 mmHg. [Guyton, TMP, lle. 2006 pp209; Stoelting, PPAP. 4e. 2006 pp7261
|
|
|
When blood pressure increases and the baroreceptors are stimulated, what happens reflexly (baroreceptor reflex) to myocardial contractility, venous tone, heart rate, systemic vascular resistance (SVR), and blood pressure?
|
When stretched, the baroreceptors fire and reflexly inhibit the sympathetic nervous system outflow resulting in a decrease in myocardial contractility, a decrease in heart rate, a decrease in venous tone, a decrease in SVR, and a decrease in blood pressure. Parasympathetic outflow is simultaneously increased, which also decreases heart rate. [Barash, Clinical Anes. 5e. 2006 pp877; Guyton, TMP. lle. 2006 pp209- 2101
|
|
|
Where are venous baro receptors located, how do they work, and what is the reflex called?
|
Venous baroreceptors are located in the right atrium and great veins. They produce an increase in heart rate when the right atrium or great veins are stretched by increased vascular volume. This reflex is called the Bainbridge reflex. [Barash, Handbook. 5e. 2006 pp150]
|
|
|
What happens to heart rate during inspiration and during expiration in the spontaneously breathing individual? Explain.
|
Heart rate increases with inspiration and decreases with expiration. During inspiration, the pressure within the thorax decreases (becomes more negative) and venous return increases. The increased venous return stretches the right atrium leading to a reflex increase in heart rate. The opposite occurs during expiration. This is the Bainbridge reflex. [Guyton, TMP. lle. 2006 pp212; Stoelting, PPAP. 4e. 2006 pp728]
|
|
|
What nerves carry the afferent and efferent signals of the Bainbridge reflex? What does the Bainbridge reflex help prevent?
|
When the great veins and right atrium are stretched by increased vascular volume, stretch receptors send afferent signals to the medulla via the vagus nerve. The medulla then transmits efferent signals via the sympathetic nerves to increase heart rate (by as much as 75%) and myocardial contractility. The Bainbridge reflex helps prevent damming up of blood in veins, the atria, and the pulmonary circulation. [Guyton, TMP. 11e. 2006 pp212]
|
|
|
What happens to arterial blood pressure during inspiration in the spontaneously breathing individual? Why?
|
Arterial blood pressure normally decreases several mmHg during inspiration. With inspiration, pulmonary venous capacitance increases and venous return to the left heart decreases. According to Starling's law, with a decrease in venous return (preload) to the left ventricle, stroke volume, cardiac output, and arterial blood pressure all decrease (even though heart rate may increase because of the Bainbridge reflex). [Barash, Clinical Anes. 5e. 2006 pp878]
|
|
|
How does a normal dorsalis pedis arterial waveform differ from the waveform found in the aorta in the supine or prone patient?
|
Pulse pressure undergoes a natural amplification during transit through the arterial tree. Compared with the aortic pressure waveform, systolic pressure is greater and diastolic pressure is lower in the dorsalis pedis. Pulse pressure is, therefore, greater in the dorsalis pedis than in the aorta. [Miller, Anesthesia. 6e. 2005 pp1282-1283; Barash, Clinical An es. 5e. 2006 p p 878]
|
|
|
Angiotensin I is converted to angiotensin II in what organ?
|
Angiotensin I is converted to angiotensin II in the pulmonary vasculature of the lung. [Guyton, TMP. lle. 2006 pp224; Barash, Clinical Anes. 5e. 2006 pp881, 1137]
|
|
|
®Which is the more potent vasoconstrictor, angiotensin II or antidiuretic hormone (ADH)?
|
Antidiuretic hormone—also called vasopressin—is even more powerful than angiotensin II as a vasoconstrictor. Barash states that angiotensin II is the more potent vasoconstrictor; realize that textual discrepancies exist. [Barash, Clinical Anes. 5e. 2006 pp1137; Guyton, TMP. lle. 2006 pp202]
|
