Cairo: Pilbeam’s Mechanical Ventilation: Physiological and Clinical Applications: 5th Edition

Chapter 11: Hemodynamic Monitoring

Workbook Answer Key

 Key Terms Crossword Puzzle

Chapter Review Questions
1.  (a) Systemic arterial pressure, (b) central venous pressure, (c) pulmonary artery pressure, (d) arterial blood gas, (e) mixed venous blood gas, and (f) cardiac output.
2.  90 beats/min ÷ 60 seconds = 1.5 seconds
3.  Valve dysfunction in the heart can cause retrograde flow.
4.  Afterload is defined as the impedance the left and right ventricles must overcome to eject blood into the great vessels.
5.  Systemic vascular resistance (SVR)
6.  Pulmonary vascular resistance (PVR)
7.  During atrial systole, the AV valves (tricuspid and mitral valves) are open and the aortic and pulmonic valves are closed.
8.  Hydrodynamic pressure
9.  Hydrostatic pressure
10.  A transducer needs to be placed at the same level or height as the catheter tip.
11.  (a) Transducer higher than the catheter tip; the pressure reading will be lower than the actual pressure, because the fluid is flowing away from the transducer. (b) Transducer lower than the catheter tip: the pressure reading will be higher than the actual pressure.
12.  The four factors that influence the outputs of the right and left ventricles are (a)heart rate, (b) preload, (c) contractility, (d) afterload
13.  Preload is the filling pressure of the ventricle at the end of ventricular diastole.
14.  Ventricular systole begins with isovolumetric contraction. During this period of contraction, the left ventricular pressure increases from 0 to 80 mm Hg and the right ventricular pressure increases from 0 to 12 mm Hg. Rapid ejection of blood occurs when the left ventricular pressure exceeds the aortic diastolic pressure of about 80 mm Hg and the right ventricular pressure exceeds the pulmonary artery diastolic pressure of 12 mm Hg. The peak systolic pressures of the ventricles are 120 mm Hg for the left ventricle and 25 mm Hg for the right ventricle.
15.	The RVEDP is estimated by the right atrial pressure (RAP) or central venous pressure (CVP); the LVEDP is estimated by the pulmonary artery wedge pressure (PAWP).
16.	Systemic vascular resistance reflects the afterload of the left ventricle. Pulmonary vascular resistance reflects the afterload of the right ventricle.
17.	The major components of a hemodynamic monitoring system include a pressure bag with flush solution, flush device, pressure tubing, transducer, cable and pressure monitor, and catheter with a heparinized solution of saline.
18.	epistatic, zero balance
19.	Proper positioning of the transducer is important for accurate measurement. If the transducer is lower than the catheter tip, the monitor will read higher than the actual pressure. If the transducer is higher than the catheter tip, the monitor will read lower than the actual pressure.
20.	Aseptically assemble, flush, and test the tubing and catheter. Perform Allen’s test to ensure an ulnar artery refill time of 5 to 10 seconds. Prep and drape the area of insertion using sterile technique. Inject lidocaine around the insertion site. Percutaneously insert the catheter at approximately a 30-degree angle. Advance the catheter into the artery while holding the needle secure. Remove the needle and secure the catheter. Attach the tubing for the drip solution and observe the monitor for the proper waveform.
21.	Problems with an arterial catheter line include infection at the site, clot formation, and distal extremity ischemia.
22.	A bag of 0.9% NaCl containing 1 to 2 units of heparin per milliliter of normal saline at 2 to 3 mL/hr.
23.	Use of a surgical cut-down to insert the arterial line, cannulation for longer than 4 days, and altered host defenses all increase the risk of infection.
24.	It can lead to overhydration.
25.	CVP lines are used to administer fluids, drugs, and nutritional solutions and to monitor right-sided heart pressures.
26.	CVP measurement at the end of ventricular diastole can estimate the filling pressure or the preload of the right ventricle, or RVEDP.
27.	Internal jugular, medial basilica, or lateral cephalic veins.
28.	CVP should be measured during exhalation with the patient in the supine position.
29.	Pneumothorax, hemothorax, vessel damage, infection, thrombosis, and bleeding.
30.	2 to 6 mm Hg
31.	Pediatric sizes are 4 and 5 Fr and 60 cm long. Adult sizes are 7 and 8 Fr and 110 cm long. All are marked in 10-cm increments.
32.	To prevent clots in the PA catheter, a pressurized flush solution is run through the catheter at a rate of 1 to 5 mL/hr, except during pressure measurements.

33.	 a. Balloon lumen b. thermistor c. distal lumen d. proximal lumen e. proximal lumen f. thermistor g. balloon (deflated)

34. Percutaneous sites: internal jugular, external jugular, and femoral veins. Surgical cut-down sites: subclavian and antecubital veins.
35.	(a) Cardiac arrhythmias—caused by irritation of a heart valve or the endocardium.
(b) Infection—caused by nonsterile technique or irritation of the wound.
(c) Pneumothorax—caused by air entering the pleural space during insertion.
(d) Air embolism—caused by air entering a vessel during insertion or by balloon rupture.
(e) Access vessel thrombosis or phlebitis—caused by irritation of the vessel by the catheter or nonsterile technique.
(f) PA rupture or perforation—caused by overinflation of the balloon.
(g) Pulmonary infarction—caused by overinflation of the balloon, prolonged wedging, clots that form in or near the catheter, or catheter advancement into a smaller artery.
(h) Catheter knotting—caused by excessive catheter movement.
(i) Dampened waveform—caused by air or kinks in the line, clot in the system, catheter tip against the vessel wall, overwedging, or blood on the transducer.
(j) Catheter whip or fling—caused by high cardiac output or abnormal vessel diameter.
36.	(a) Fluoroscopy (in the catheterization laboratory) or (b) pressure tracings (in the critical care setting).
37.	Internal jugular vein to the superior vena cava, where the balloon is inflated. The balloon then floats through the right atrium and right ventricle. It is advanced until it wedges in a small pulmonary artery in West’s zone 3 of the lungs.
38.	The PAC needs to be in zone 3 because this zone accurately reflects the pulmonary venous pressure. If the PAC is placed in zone 1 or 2 in the lung, the balloon will collapse when inflated, because the alveolar pressure exceeds the pulmonary venous pressure.
39. 

Zone	Pressure Relationship	
1	PA > Pa >            	
2	Pa > PA > 	
3	Pa >  > PA	

40.	1.5 mL; 15 to 30 seconds
41.	(a), Right atrium; (b), right ventricle; (c), pulmonary artery; (d), pulmonary artery wedge.
42.	a.  Ventricular arrhythmias—careful ECG monitoring during catheter placement.
b.  Pulmonary artery infarction—prevent thrombus by using continuous flushed solution containing heparin and ensure balloon deflation after wedge pressure measurements.
c.  Pulmonary artery rupture—ensure that catheter balloon is deflated after wedge pressure measurements are made and inflate for only 15 to 30 seconds.
d.  Balloon rupture—do not overinflate; maximum balloon volume in adult catheters is 1.5 mL.
43.	When heart rates are that rapid, diastolic filling time decreases.
44.	Diastolic pressure will increase.
45.	stroke volume; arterial compliance
46.	PAP is read at the end of expiration.
47.	PEEP or auto PEEP > 15 cm H2O produces an erroneously high PAWP.
48.	(1) Pulmonary hypertension, (2) pulmonary embolus, and (3) CHF.
49.	Nitric oxide selectively dilates the pulmonary vasculature and decreases pulmonary vascular resistance, thereby reducing the pulmonary artery pressure.
50.	During spontaneous breathing, the pulmonary artery pressure falls on inspiration and rises during expiration. In contrast, during mechanical ventilation, the pulmonary artery pressure rises during inspiration and falls during expiration.
51.	
Parameter	Normal Value	
Arterial blood pressure	90-140/60-90 mm Hg	
Mean arterial pressure	70 to 100 mm Hg	
Pulse pressure	40 mm Hg	
Central venous pressure	2 to 6 mm Hg	
Pulmonary artery pressure	15-35/5-15 mm Hg	
Mean pulmonary artery pressure	10 to 20 mm Hg	
Pulmonary artery wedge pressure 	5 to 12 mm Hg	

52.	
Calculate Value	Formula	Normal Values	
Cardiac output	Stroke volume × Heart rate	4 to 8 L/min	
Cardiac index	CO ÷ BSA	2.5 to 4 L/min/m2	
Stroke index	SV ÷ BSA	35 to 55 mL/beat/m2	
Arterial oxygen content	[Hb × %sat × 1.34] + [PaO2 × 0.00031]	20 vols%	
Mixed venous oxygen content	[Hb × %sat × 1.34] + [PvO2 × 0.00031]	15 vols%	
Systemic vascular resistance	[MAP – (CVP ÷ CO)] × 80 	900 to 1500 dynes × sec × m-5	
Pulmonary vascular resistance	[MPAP – (PAWP ÷ CO)] × 80	100 to 250 dynes × sec × m-5	

53.    
Factor	Effect on Cardiac Output	
Tachycardia   	Increases CO	
Beta-adrenergic blockade	Decreases CO	
Increased parasympathetic tone	Decreases CO	
Increased preload and contractility	Increases CO	
Bradyarrhythmias	Decreases CO	
Decreased parasympathetic tone	Increases CO	

54.	CaO2 = (SaO2 × 1.34 × Hb) + (PaO2 × 0.00031)
= (0.75 × 1.34 × 10) + (43 × 0.00031)	= 10.06 vols%
55.	CaO2 = (SaO2 × 1.34 × Hb) + (PaO2 × 0.00031)
= (0.94 × 1.34 × 13) + 64 × 0.00031)	= 16.39 vols%
56.	CvO2 = (SvO2 × 1.34 × Hb) + (PvO2 × 0.00031)
= 0.75 × 1.34 × 15) + (40 × 0.00031)	= 15.09 vols%
57.	CvO2 = (SvO2 × 1.34 × Hb) + (PvO2 × 0.00031)
= 0.85 × 1.34 × 16) + (70 × 0.00031)	= 18.24 vols%
58.	When cardiac output is reduced, the blood flows slower through the vessels, giving the tissues more time to extract oxygen from the blood.
59.	The caliber of the blood vessels and the viscosity of the blood are the two factors. (a) Vasoconstriction and (b) polycythemia increase SVR. 
60.	Both alveolar hypoxia and high intra-alveolar pressure cause the PVR to increase.
61.	(any of the following) Stroke volume, ejection fraction, stroke work, and stroke work index.

Critical Thinking Questions
1.  The appropriate place for a pulmonary artery catheter is resting with the balloon deflated in zone 3 in the lung. When the wedge pressure is measured, the balloon is inflated. The catheter tip then reads the pressure in front of the catheter. This reflects the pressure in the left atrium. During early ventricular diastole, the mitral valve is open and the left atrium passively empties into the left ventricle. At this point, the pulmonary artery wedge pressure reflects the left ventricular end-diastolic pressure. LVEDP is an index of left ventricular end-diastolic volume and is used to evaluate left ventricular function.
2.	 Cardiogenic pulmonary edema occurs when left ventricular function decreases to the point where the left side of the heart is unable to maintain left ventricular stroke volume adequately. When this occurs, blood backs up into the lungs and increases the pulmonary capillary hydrostatic pressure. The pulmonary capillary hydrostatic pressure is the primary determinant of fluid shift from the capillaries into the lung tissue. Therefore, with cardiogenic pulmonary edema, the pulmonary artery occlusion pressure is elevated, usually > 18 mm Hg. In noncardiogenic pulmonary edema, fluid leaks into the alveoli, not because of left ventricular failure but because of fluid and protein leakage caused by a disruption of the pulmonary capillary membrane.
3.	 Nitroprusside is composed of 5 cyanide molecules, 1 nitric oxide (NO) molecule, and 1 iron atom. The nitric oxide molecule is where all the action takes place. When released, it acts on venous and arterial smooth muscle cells. NO increases the activity of the enzyme guanylate cyclase, which causes increased cyclic-GMP levels inside cells. Cyclic-GMP binds to receptors on smooth muscle cells, which causes calcium (the main electrolyte responsible for muscle contraction) to get pushed back into the endoplasmic reticulum. Less calcium means less smooth muscle contraction, which causes blood vessels to dilate. The end result is a decrease in systemic vascular resistance and blood pressure. Tolazoline causes vasodilation by competitively blocking alpha-adrenergic receptors to produce brief antagonism of circulating epinephrine and norepinephrine. It reduces hypertension caused by catecholamines and causes vascular smooth muscle relaxation (direct action). This results in peripheral vasodilation and decreased peripheral resistance. In addition, tolazoline usually reduces pulmonary arterial pressure. 
4.	 Pulse pressure is the difference between the systolic blood pressure and the diastolic blood pressure. The pulse pressure can be increased either by an increase in the systolic pressure or by a decrease in the diastolic pressure. Causes of an increase in pulse pressure include hypervolemia, arteriosclerosis (noncompliant blood vessels), and bradycardia (which lowers the diastolic pressure). The pulse pressure can be decreased either by decreasing the systolic pressure or by increasing the diastolic pressure. The causes of a decreased pulse pressure include hypovolemia, shock, and tachycardia (which increases the diastolic pressure).

Case Studies
Case Study 1 
1.	 Pulse pressure = Systolic BP – Diastolic BP = 145 – 68 = 77 mm Hg ↑
2.	 Stroke volume = CO ÷ HR = 5.1 L/min ÷ 92 beats/min = 55.4 mL ↓
3.	 Stroke index = SV ÷ BSA = 55.43 mL ÷ 2.1 m2 = 26.4 mL/beat/m2 ↓
4.	 Cardiac index = CO ÷ BSA = 5.1 L/min ÷ 2.1 m2 = 2.4 L/min/m2 ↓
5.	 Mean arterial pressure = [145 + 2(68)] ÷ 3 = 93.7 mm Hg WNL (within normal limits)
6.	 Mean pulmonary artery pressure = [38 + 2(20)] ÷ 3 = 26 mm Hg ↑
7.	 SVR = [(MAP – CVP) ÷ CO] × 80 = [(93.7 – 12) ÷ 5.1] × 80 = 1281.6 dynes/cm/sec5 WNL (within normal limits)
8.  PVR = [(MPAP – PAWP) ÷ C.O.] × 80 = [(26 – 10) ÷ 5.1] × 80 = 251 dynes/cm/sec5 ↑ slightly
9.  CaO2 = [(1.34 × SaO2 × Hb) + (PaO2 × 0.0031)] = [(1.34 × 0.99 × 12.6) + (100 × 0.0031)] = 17 vols% ↓
10.  CvO2 = [(1.34 × 0.75 × 12.6) + (40 × 0.0031)] = 12.8 vols% ↓
11.  C(a-v)O2 = CaO2 - CvO2 = 17 – 12.8 = 4.2 vols% WNL
12.  DO2 = CO × CaO2 = 5.1 L/min/m2 × 170 mL/L = 867 mL/min WNL
13.  VO2 = CO × C(a-v)O2 = 5.1 L/min/m2 × 42 mL/L = 214.2 mL/min WNL
14.  RVSW = MPAP × SV × 0.0136 = 26 × 55.4 × 0.0136 = 19.6 g•m WNL
15.  RVSWI = RVSW ÷ BSA = 19.6 gm-m2 ÷ 2.1 m2 = 9.3 g•m/m2 WNL
16.  LVSW = MAP x SV x 0.0136 = 93.7 x 55.4 x 0.0136 = 70.6 g•m WNL
17.  LVSWI = LVSW ÷ BSA = 70.6 g-m/m2 ÷ 2.1 m2 = 33.6 g•m/m2 ↓
18.  The patient’s hemoglobin is low, which decreases the blood’s oxygen-carrying capacity. Both PAP and CVP are elevated, which may be due to the slightly high PVR. Given the patient’s history of present illness, he may be developing ARDS.

Case Study 2
1.  Hemodynamic monitoring of the pulmonary artery pressure and pulmonary capillary wedge pressure would most likely be useful for this patient.
2.  A right-sided pneumothorax.
3.  The pneumothorax is most likely due to the insertion of the pulmonary artery catheter.
4.  The elevated PAOP indicates cardiogenic pulmonary edema from left-sided heart failure.

NBRC-Style Questions
1.  C	
2.  D	
3.  B	
4.  D	
5.  A	 
6.  A	
7.  D
8.  B	
9.  D	
10.  B	
11.  A	
12.  D
13.  A
14.  A	
15.  C