Hemodynamic practice Assignment
Calculate the arterial oxygen content for a patient with the following arterial blood gas measurements: Hgb = 9 g%, arterial oxygen saturation (SaO2) = 96%, arterial partial pressure of oxygen (PaO2) = 97 mm Hg.
11.9 vol% CaO2 = (Hgb x 1.34 x SaO2) + (PaO2 x 0.003)
The stretching of the ventricle before the next contraction is called:
preload
Calculate the ejection fraction of a female patient with a stroke volume of 40 mL and an end-diastolic volume of 125 mL.
0.32
Calculate the cardiac index for a patient with the following data: heart rate = 80 beats/min, stroke volume = 55 mL, and body surface area = 2.8 m2.
0.57 L/min/m2
Which of the following statements is true concerning the insertion of a radial arterial line? 1. The catheter tip must face upstream. 2. The catheter tip must face downstream. 3. The transducer must be higher than the catheter tip. 4. The transducer must be level with the catheter tip.
1 and 4 only When a catheter faces the source of blood flow it is "looking" upstream. An arterial line placed in the radial artery needs to face the blood flow to accurately measure pressures that are a result of left heart work. If the catheter faces downstream it reads the pressures ahead of it. To accurately measure pressure, the transducer needs to be at the same height or level with the tip of the catheter. If the transducer is higher than the catheter tip the fluid will be flowing away from the transducer and will produce a reading lower than the actual pressure.
A pulmonary artery (Swan-Ganz) catheter can be used for which of the following? 1. Measuring cardiac output 2. Arterial blood sampling 3. Measuring left atrial pressure 4. Measuring pulmonary artery pressure
1, 3, 4 A pulmonary artery (Swan-Ganz) catheter can be used to sample mixed venous blood. Arterial blood sampling requires an arterial (radial) catheter. The other listed options can be performed with a pulmonary artery catheter.
Calculate a 90-kg patient's cardiac index with the following measurements: cardiac output 3.8 L/min, body surface area 3 m2.
1.3 L/min/m2 CI = C.O. / BSA
The following hemodynamic measurements were obtained from a patient in the intensive care unit: pulmonary artery pressure (PAP) = 67/25 mm Hg, pulmonary artery occlusion pressure (PAOP) = 18 mm Hg, blood pressure (BP) = 100/50 mm Hg, central venous pressure (CVP) = 17 mm Hg, cardiac output (C.O.) = 5.7 L/min, and heart rate (HR) = 75 beats/min. Calculate this patient's systemic vascular resistance (SVR).
1165 dynes x s x cm^-5 SVR = [(MAP - CVP) / C.O.] x 80
Which of the following is the range for the time a pulmonary artery catheter should be inflated?
15-30 s Fifteen to thirty seconds will allow enough time to stabilize the reading and avoid balloon rupture or pulmonary infarction.
A patient with the hemodynamic values below has a cardiac output of which of the following? Oxygen consumption 380 mL/min Arterial oxygen content 23.2 vol% Mixed venous oxygen content 10.3 vol%
2.9 mL/min C.O. = VO2 / [(CaO2 - CvO2) x 10]
A patient with a mitral valve stenosis is most likely to have which of the following pulmonary artery occlusion pressure (PAOP) values?
20 mm Hg The normal range for pulmonary artery occlusion pressure (PAOP) is 5-12 mm Hg. Mitral valve stenosis is the cause of an abnormally high PAOP. Therefore the value of 20 mm Hg is the correct answer.
Calculate the arterial oxygen content for a patient with the following arterial blood gas measurements: Hgb = 17 g%, arterial oxygen saturation (SaO2) = 93%, arterial partial pressure of oxygen (PaO2) = 64 mm Hg.
21.4 vol%
Calculate the pulmonary vascular resistance (PVR) given the following measurements obtained during a hemodynamic study: pulmonary artery pressure (PAP) = 40/22 mm Hg, pulmonary artery occlusion pressure (PAOP) = 12 mm Hg, blood pressure (BP) = 156/80 mm Hg, central venous pressure (CVP) = 19 mm Hg, cardiac output (C.O.) = 4.8 L/min, and heart rate (HR) = 68 beats/min.
267 x s x cm^-5
The following hemodynamic measurements were obtained from a patient in the intensive care unit: pulmonary artery pressure (PAP) = 67/25 mm Hg, pulmonary artery occlusion pressure (PAOP) = 18 mm Hg, blood pressure (BP) = 100/50 mm Hg, central venous pressure (CVP) = 17 mm Hg, cardiac output (C.O.) = 5.7 L/min, and heart rate (HR) = 75 beats/min. Calculate this patient's pulmonary vascular resistance (PVR).
295 dyne x s x cm^-5
Calculate cardiac output using the Fick principle for the following values: Oxygen consumption 280 mL/min Arterial oxygen content 19.5 vol% Mixed venous oxygen content 12 vol%
3.7 L/min C.O. = VO2 / [(CaO2 - CvO2) x 10 ]
Calculate the cardiac index using the following data:Cardiac output = 4.6 L/minBody surface area = 1.2 m2
3.8 L/min/m2
A patient with an oxygen consumption of 340 mL/min, arterial oxygen content of 17.3 vol%, and mixed venous oxygen content of 12.8 vol% has a cardiac output of which of the following?
7.6 mL/min C.O. = VO2 / [(CaO2 - CvO2) x 10]
A patient in the ICU has a chest X-ray that shows bilateral infiltrates and has the following hemodynamic measurements: central venous pressure (CVP) 5 mm Hg, pulmonary artery pressure (PAP) 24/13 mm Hg, and pulmonary artery occlusion pressure (PAOP) 21 mm Hg. These findings are consistent with which of the following?
Cardiogenic pulmonary edema
Which of the following measurements can be used to estimate right ventricular preload?
Central venous pressure Central venous pressure (CVP) is used to estimate the right ventricular preload. Pulmonary artery occlusion pressure (PAOP) reflects the preload of the left ventricle. The pulmonary artery pressure is generated by the right ventricle ejecting blood into the pulmonary circulation, which acts as a resistance to the output from the right ventricle. The pulmonary artery pressure (PAP) is a measurement of right ventricular afterload. Cardiac output is the amount of blood that the heart pumps out each minute.
Which of the following is the hemodynamic measurement that is indicative of a patient with right heart failure?
Central venous pressure (CVP) = 16 mm Hg The normal range for pulmonary artery occlusion pressure (PAOP) is 5-12 mm Hg, for central venous pressure (CVP) 2-6 mm Hg, for pulmonary artery pressure (PAP) 15-35/5-15 mm Hg, and for mean arterial pressure (MAP) 70-100 mm Hg. Right heart failure causes the CVP to increase significantly. Answer B shows a CVP that is greatly increased and is therefore indicative of right heart failure
The dicrotic notch recorded in the aorta immediately follows what mechanical event of the cardiac cycle?
Closure of the aortic valve
Which of the following is the function of the transducer in the invasive vascular monitoring system?
Convert the fluid pressure to an electrical signal. The transducer has two main compartments. One, called the dome, contains the fluid that enters it from a plastic line connected to the indwelling catheter. The dome is separated from the electrical portion of the transducer by a flexible diaphragm. Changes in fluid pressure result in movement of the diaphragm, which causes an increase or decrease in the length of the wires of the Wheatstone bridge contained in the electrical portion of the transducer. The transducer is therefore able to detect small physiological signal changes and convert them to electrical impulses or signals.
An intubated patient with no known history of congestive heart failure is in the ICU. The patient is comatose and currently receiving mechanical ventilation via volume-controlled continuous mandatory ventilation (VC-CMV), set rate 12 breaths/min, set tidal volume (VT) 400 mL, positive end-expiratory pressure (PEEP) 18 cm H2O, fractional inspired oxygen (FIO2) 0.35, and the patient is not assisting. Hemodynamic measurements show the following: central venous pressure (CVP) 5 mm Hg, pulmonary artery pressure (PAP) 33/20 mm Hg, and pulmonary artery occlusion pressure (PAOP) 16 mm Hg. Arterial blood gas (ABG) results are: pH 7.43, arterial partial pressure of carbon dioxide (PaCO2) 38 mm Hg, arterial partial pressure of oxygen (PaO2) 90 mm Hg. The physician asks for recommendations to improve this patient's hemodynamics. The most appropriate recommendation for this patient is which of the following?
Decrease the PEEP incrementally and recheck hemodynamic measurements. The patient's central venous pressure (CVP) is within normal limits. The pulmonary artery pressure (PAP) and pulmonary artery occlusion pressure (PAOP) are both elevated. These hemodynamic results are consistent with left ventricular failure. However, when looking at the ventilator settings it should be noted that the set positive end-expiratory pressure (PEEP) is >15 cm H2O. This setting will prolong changes in lung zones and produce erroneously elevated pressure readings by squeezing the pulmonary vessels and overinflating the lungs. Changing the mode to pressure support ventilation (PSV) or synchronized intermittent mandatory ventilation (SIMV) will lower the mean inspiratory pressures and minimize the hemodynamic effects of positive intrathoracic pressure. However, this patient is comatose so PSV is not an option (choice "A") and changing to volume-controlled synchronized intermittent mandatory ventilation (VC-SIMV) with the same PEEP level (choice "C") will have little effect on the hemodynamics. Pressure ventilation (choice "D") will have about the same effect on the patient's hemodynamic values as the current settings. Decreasing the PEEP incrementally and checking the hemodynamic measurements can be used to optimize the PEEP level for this patient.
Right atrium This figure shows a pressure range of 2-6 mm Hg which is consistent with the right atrium. It also shows the characteristic respiratory fluctuations. The systolic pressure for the right ventricle is as high as 25 mm Hg, which is not seen in the figure. The systolic and diastolic ranges for pulmonary artery pressure are 15-35 and 5-15 mm Hg, respectively. This is higher than what is shown in the figure. Pulmonary capillary pressure when wedged is usually between 5 and 12 mm Hg, which is somewhat higher than what is shown in the figure.
During the introduction of a pulmonary artery catheter the waveform seen in the figure is visible on the monitor. This waveform represents which of the following locations?
Ventricular contractility can be estimated by which of the following?
Ejection fraction
Which of the following can be used to estimate the contractility of the ventricles?
Ejection fraction The ejection fraction is a way of estimating the force that the ventricle generates during each cardiac cycle. It is calculated as the ratio of the stroke volume to the ventricular end-diastolic volume. Systemic vascular resistance is used to describe the afterload that the left ventricle must overcome to eject blood into the systemic circulation. The pulmonary vascular resistance reflects the afterload that the right ventricle must overcome to eject blood into the pulmonary circulation. The right ventricular end-diastolic pressure is used as an indicator of the right ventricular preload and the left ventricular end-diastolic pressure is used to indicate left ventricular preload.
Which of the following is not a complication that may occur during the insertion of a central venous pressure line?
Infection It usually takes several hours to days for an infection to develop, so infection would not occur during the insertion of the central venous pressure (CVP) catheter. Bleeding, pneumothorax, and vessel damage are all complications that may occur during the insertion of the catheter.
Which of the following describes the filling pressure of the ventricle at the end of ventricular diastole?
Preload
Advancing a pulmonary artery catheter into a smaller artery may cause which of the following complications?
Pulmonary infarction A pneumothorax may be caused during the insertion procedure. An air embolism may be caused by the rupture of the balloon if overinflated or during insertion. A pulmonary infarction may be caused by the catheter being advanced into a smaller artery or by overinflation of the balloon, prolonged wedging, or clot formation. Ventricular fibrillation would most likely be caused during the insertion process when the endocardium is irritated by the catheter while it is passing through the heart.
While attempting to draw blood from an indwelling arterial catheter, the respiratory therapist notices a dampened waveform and has difficulty withdrawing blood for sampling. What should the respiratory therapist's immediate action be?
Remove the catheter. The presence of both a persistently dampened waveform and difficulty withdrawing blood indicates that there is a clot. To avoid any adverse effects the catheter should be removed. Flushing the catheter could cause the blood clot to move into the patient's circulation and has the potential to cause an infarction in the brain, heart, or lungs. Repositioning the catheter will not remove the clot. Recalibrating the transducer will not remove the clot.
Calculate the stroke volume (SV) and the stroke volume index (SI) using the following information: cardiac output = 4.5 L/min, heart rate = 110 beats/min, and body surface area = 1.3 m2.
SV = 41 mL; SI = 31.5 mL/m2
Which of the following is an indication of left ventricular afterload?
Systemic vascular resistance The systemic vascular resistance is the resistance the left ventricle must contract against to eject blood into the systemic circulation. Ejection fraction is a measurement of contractility. Pulmonary vascular resistance is the resistance the right ventricle must contract against to eject blood into the pulmonary circulation. Left ventricle end-diastolic pressure (LVEDP) is used to estimate left ventricular preload.
The period of relaxation in the cardiac cycle is known as:
diastole
Pulmonary artery The figure shows a systolic pressure of approximately 22 mm Hg and a diastolic of approximately 8-10 mm Hg. This falls within the normal pulmonary artery pressures of . The presence of the dicrotic notch is another hint that the catheter is in the pulmonary artery. The right atrial pressure is normally between 2 and 6 mm Hg. A catheter in the right ventricle would show pressures of 15 - 35/2 - 6 mm Hg. The pulmonary capillary wedge pressure (PCWP or PAOP) normally varies between 2 and 15 mm Hg.
The waveform of a pulmonary catheter, shown in the figure, is located in which of the following?
A central venous pressure (CVP) catheter is used to:
monitor right ventricular function.
The amount of blood ejected by the heart per unit of time is called:
cardiac output
Absolute confirmation of placement of a central venous pressure catheter is done with which of the following?
chest x-ray
