Pulmonary artery catheter
Encyclopedia
In medicine
pulmonary artery catheterization (PAC) is the insertion of a catheter
into a pulmonary artery
. Its purpose is diagnostic
; it is used to detect heart failure or sepsis
, monitor therapy, and evaluate the effects
of drugs
. The pulmonary artery catheter allows direct, simultaneous measurement of pressures in the right atrium, right ventricle, pulmonary artery, and the filling pressure ("wedge" pressure) of the left atrium.
The pulmonary artery catheter is frequently referred to as a Swan-Ganz catheter, in honor of its inventors Jeremy Swan
and William Ganz
, from Cedars-Sinai Medical Center
. The idea for a sail or balloon tip modification of Ronald Bradley's simple portex tubing method came about from Dr Swan's observation from the Santa Monica shore of sail boats on the water on relatively calm day. Boats with conventional slot sails were still; one with a spinnaker
was able to make reasonable headway. Ganz added the thermistor
after Swan showed him the initial balloon design, which was fabricated by Edwards Laboratories, which had previously contracted with Swan as a consultant.
Note: No study has definitively demonstrated improved outcome in critically ill patients managed with PA catheters.. Therefore, the primary justification has been on the basis of clinic experience.
, subclavian
, or femoral
veins. From this entry site, it is threaded, often with the aid of fluoroscopy
, through the right atrium
of the heart
, the right ventricle
, and subsequently into the pulmonary artery.
The standard pulmonary artery catheter has two lumens (Swan-Ganz) and is equipped with an inflatable balloon
at the tip, which facilitates its placement into the pulmonary artery through the flow of blood. The balloon, when inflated, causes the catheter to "wedge" in a small pulmonary blood vessel. So wedged, the catheter can provide an indirect measurement of the pressure in the left atrium of the heart, showing a mean pressure, in addition to a, x, v, and y waves which have implications for status of the left atria and the mitral valve. Left ventricular end diastolic pressure (LVedp) is measured separately, with a catheter that has directly crossed the aortic valve
and is well positioned in the left ventricle. LV edp reflects fluid status of the individual in addition to heart health. See also pulmonary wedge pressure and ventricular pressure
.
(temperature probe) about 3 cm behind the tip. Either cold 10 ml of saline (0.9% NaCl) under 10° Celsius or room temperature (not as accurate) is injected into an opening in the right atrium
. As this cooler fluid passes the tip thermistor, a very brief drop in the blood temperature is recorded. A recent variation in design is the incorporation of a heating coil on the catheter (30cms from the tip, residing in the atrium area) which eliminates the cold fluid bolus, a major factor in human technique variation.
By attaching both the injector site and the ventricular thermistor to a small computer, the thermodilution curve can be plotted. If details about the patient's body mass index (size); core temp, Systolic, diastolic, central venous pressure CVP (measured from the atrium by the third lumen simultaneously) and pulmonary artery pressure are input, a comprehensive flow vs pressure map can be calculated.
In crude terms, this measurement compares left and right cardiac activity and calculates preload
and afterload
flow and pressures which theoretically if stabilized or adjusted with drugs to either constrict or dilate the vessels to raise or lower the pressure of blood flow to the lungs, respectively, in order to maximize oxygen for delivery to the body tissues.
The ability to record results is not a guarantee of patient survivability. The true art remains with the consultant physician or intensivist in balancing fluid load, so much so that the introduction of a balloon catheter, which is usually yellow, has been nicknamed "The kiss of the yellow snake".
s — five or six are common — and have openings along the length to allow administration of inotropes and other drugs directly into the atrium. Drugs to achieve these changes can be delivered into the atrium via the fourth lumen, usually dedicated to medication. Common drugs used are various inotropes, nor-adrenaline or even atropine
. A further set of calculations can be made by measuring the arterial blood and central venous (from the third lumen) and inputting these figures into a spreadsheet or the cardiac output computer, if so equipped, and plotting an oxygen delivery profile.
, infection
, pneumothorax
, bleeding
, and other problems.
by time/temperature curves is an expedient but limited and invasive model of right heart performance. It remains an exceptional method of monitoring volume overload leading to pulmonary edema in an ICU setting.
Noninvasive Echocardiography
and pulse-wave cardiac output monitoring are concordant with (and much safer) if not better than invasive methods defining right and left heart performance. The advent of MRSA and similar hospital based catheter infections now clearly limits the utility of this type of invasive cardiac ICU intervention.
Medicine
Medicine is the science and art of healing. It encompasses a variety of health care practices evolved to maintain and restore health by the prevention and treatment of illness....
pulmonary artery catheterization (PAC) is the insertion of a catheter
Catheter
In medicine, a catheter is a tube that can be inserted into a body cavity, duct, or vessel. Catheters thereby allow drainage, administration of fluids or gases, or access by surgical instruments. The process of inserting a catheter is catheterization...
into a pulmonary artery
Pulmonary artery
The pulmonary arteries carry deoxygenated blood from the heart to the lungs. They are the only arteries that carry deoxygenated blood....
. Its purpose is diagnostic
Diagnosis
Diagnosis is the identification of the nature and cause of anything. Diagnosis is used in many different disciplines with variations in the use of logics, analytics, and experience to determine the cause and effect relationships...
; it is used to detect heart failure or sepsis
Sepsis
Sepsis is a potentially deadly medical condition that is characterized by a whole-body inflammatory state and the presence of a known or suspected infection. The body may develop this inflammatory response by the immune system to microbes in the blood, urine, lungs, skin, or other tissues...
, monitor therapy, and evaluate the effects
Causality
Causality is the relationship between an event and a second event , where the second event is understood as a consequence of the first....
of drugs
Medication
A pharmaceutical drug, also referred to as medicine, medication or medicament, can be loosely defined as any chemical substance intended for use in the medical diagnosis, cure, treatment, or prevention of disease.- Classification :...
. The pulmonary artery catheter allows direct, simultaneous measurement of pressures in the right atrium, right ventricle, pulmonary artery, and the filling pressure ("wedge" pressure) of the left atrium.
The pulmonary artery catheter is frequently referred to as a Swan-Ganz catheter, in honor of its inventors Jeremy Swan
Jeremy Swan
H.J.C. "Jeremy" Swan was an Irish cardiologist, originally from Sligo, who co-invented the Swan-Ganz catheter with William Ganz at Cedars-Sinai Medical Center in 1970....
and William Ganz
William Ganz
William Ganz was a Slovakian-born American cardiologist who co-invented the pulmonary artery catheter, often referred to as the Swan-Ganz catheter, with Jeremy Swan in 1970. The catheter is used to monitor heart conditions, especially in intensive care units...
, from Cedars-Sinai Medical Center
Cedars-Sinai Medical Center
Originally established as Kaspare Cohn Hospital in 1902, Cedars-Sinai Medical Center is a non-profit, tertiary 958-bed hospital and multi-specialty academic health science centre located in Los Angeles, California, US. Part of the Cedars-Sinai Health System, the hospital employs a staff of over...
. The idea for a sail or balloon tip modification of Ronald Bradley's simple portex tubing method came about from Dr Swan's observation from the Santa Monica shore of sail boats on the water on relatively calm day. Boats with conventional slot sails were still; one with a spinnaker
Spinnaker
A spinnaker is a special type of sail that is designed specifically for sailing off the wind from a reaching course to a downwind, i.e. with the wind 90°–180° off the bow. The spinnaker fills with wind and balloons out in front of the boat when it is deployed, called flying. It is constructed of...
was able to make reasonable headway. Ganz added the thermistor
Thermistor
A thermistor is a type of resistor whose resistance varies significantly with temperature, more so than in standard resistors. The word is a portmanteau of thermal and resistor...
after Swan showed him the initial balloon design, which was fabricated by Edwards Laboratories, which had previously contracted with Swan as a consultant.
Indications
General indications are:- Management of complicated myocardial infarctionMyocardial infarctionMyocardial infarction or acute myocardial infarction , commonly known as a heart attack, results from the interruption of blood supply to a part of the heart, causing heart cells to die...
- Hypovolemia vs cardiogenic shockCardiogenic shockCardiogenic shock is based upon an inadequate circulation of blood due to primary failure of the ventricles of the heart to function effectively....
- Ventricular septal rupture (VSR) vs acute mitral regurgitation
- Severe left ventricular failure
- Right ventricular infarction
- Unstable angina
- Refractory ventricular tachycardiaTachycardiaTachycardia comes from the Greek words tachys and kardia . Tachycardia typically refers to a heart rate that exceeds the normal range for a resting heart rate...
- Hypovolemia vs cardiogenic shock
- Assessment of respiratory distress
- Cardiogenic vs non-cardiogenic pulmonary edemaPulmonary edemaPulmonary edema , or oedema , is fluid accumulation in the air spaces and parenchyma of the lungs. It leads to impaired gas exchange and may cause respiratory failure...
- Primary vs secondary pulmonary hypertensionPulmonary hypertensionIn medicine, pulmonary hypertension is an increase in blood pressure in the pulmonary artery, pulmonary vein, or pulmonary capillaries, together known as the lung vasculature, leading to shortness of breath, dizziness, fainting, and other symptoms, all of which are exacerbated by exertion...
- Cardiogenic vs non-cardiogenic pulmonary edema
- Assessment of type of shock
- Assessment of therapy
- AfterloadAfterloadAfterload is the tension or stress developed in the wall of the left ventricle during ejection. Following Laplace's law, the tension upon the muscle fibers in the heart wall is the product of the pressure within the ventricle, multiplied by the volume within the ventricle, divided by the wall...
reduction - Vasopressors
- Beta blockerBeta blockerBeta blockers or beta-adrenergic blocking agents, beta-adrenergic antagonists, beta-adrenoreceptor antagonists or beta antagonists, are a class of drugs used for various indications. They are particularly for the management of cardiac arrhythmias, cardioprotection after myocardial infarction ,...
s - Intra-aortic balloon counter-pulsation
- Afterload
- Assessment of fluid requirement in critically ill patients
- Hemorrhage
- Sepsis
- Acute renal failureAcute renal failureAcute kidney injury , previously called acute renal failure , is a rapid loss of kidney function. Its causes are numerous and include low blood volume from any cause, exposure to substances harmful to the kidney, and obstruction of the urinary tract...
aka Acute Kidney Injury - Burns
- Management of postoperative open heart surgical patients
- Assessment of valvular heart diseaseHeart diseaseHeart disease, cardiac disease or cardiopathy is an umbrella term for a variety of diseases affecting the heart. , it is the leading cause of death in the United States, England, Canada and Wales, accounting for 25.4% of the total deaths in the United States.-Types:-Coronary heart disease:Coronary...
- Assessment of cardiac tamponade/constriction
Note: No study has definitively demonstrated improved outcome in critically ill patients managed with PA catheters.. Therefore, the primary justification has been on the basis of clinic experience.
Procedure
The catheter is introduced through a large vein—often the internal jugularInternal jugular vein
The two internal jugular veins collect the blood from the brain, the superficial parts of the face, and the neck.-Path:On both sides and at the base of the brain, the inferior petrosal sinus and the sigmoid sinus join to form the internal jugular vein...
, subclavian
Subclavian vein
The subclavian veins are two large veins, one on either side of the body. Their diameter is approximately that of the smallest finger.-Path:Each subclavian vein is a continuation of the axillary vein and runs from the outer border of the first rib to the medial border of anterior scalene muscle...
, or femoral
Femoral vein
In the human body, the femoral vein is a blood vessel that accompanies the femoral artery in the femoral sheath. It begins at the adductor canal and is a continuation of the popliteal vein...
veins. From this entry site, it is threaded, often with the aid of fluoroscopy
Fluoroscopy
Fluoroscopy is an imaging technique commonly used by physicians to obtain real-time moving images of the internal structures of a patient through the use of a fluoroscope. In its simplest form, a fluoroscope consists of an X-ray source and fluorescent screen between which a patient is placed...
, through the right atrium
Atrium (anatomy)
In anatomy, the atrium , sometimes called auricle , refers to a chamber or space. For example, the term is used for a portion of the lateral ventricle in the brain and the blood collection chamber of the heart...
of the heart
Heart
The heart is a myogenic muscular organ found in all animals with a circulatory system , that is responsible for pumping blood throughout the blood vessels by repeated, rhythmic contractions...
, the right ventricle
Ventricle (heart)
In the heart, a ventricle is one of two large chambers that collect and expel blood received from an atrium towards the peripheral beds within the body and lungs. The Atria primes the Pump...
, and subsequently into the pulmonary artery.
The standard pulmonary artery catheter has two lumens (Swan-Ganz) and is equipped with an inflatable balloon
Balloon
A balloon is an inflatable flexible bag filled with a gas, such as helium, hydrogen, nitrous oxide, oxygen, or air. Modern balloons can be made from materials such as rubber, latex, polychloroprene, or a nylon fabric, while some early balloons were made of dried animal bladders, such as the pig...
at the tip, which facilitates its placement into the pulmonary artery through the flow of blood. The balloon, when inflated, causes the catheter to "wedge" in a small pulmonary blood vessel. So wedged, the catheter can provide an indirect measurement of the pressure in the left atrium of the heart, showing a mean pressure, in addition to a, x, v, and y waves which have implications for status of the left atria and the mitral valve. Left ventricular end diastolic pressure (LVedp) is measured separately, with a catheter that has directly crossed the aortic valve
Aortic valve
The aortic valve is one of the valves of the heart. It is normally tricuspid , although in 1% of the population it is found to be congenitally bicuspid . It lies between the left ventricle and the aorta....
and is well positioned in the left ventricle. LV edp reflects fluid status of the individual in addition to heart health. See also pulmonary wedge pressure and ventricular pressure
Ventricular pressure
Ventricular pressure is a measure of blood pressure within the ventricles of the heart.-Left ventricular pressure:During most of the cardiac cycle, ventricular pressure is less than the pressure in the aorta, but during systole, the ventricular pressure rapidly increases, and the two pressures...
.
Thermal dilution
After Swan developed the initial balloon tip, Ganz added a small thermistorThermistor
A thermistor is a type of resistor whose resistance varies significantly with temperature, more so than in standard resistors. The word is a portmanteau of thermal and resistor...
(temperature probe) about 3 cm behind the tip. Either cold 10 ml of saline (0.9% NaCl) under 10° Celsius or room temperature (not as accurate) is injected into an opening in the right atrium
Right atrium
The right atrium is one of four chambers in the hearts of mammals and archosaurs...
. As this cooler fluid passes the tip thermistor, a very brief drop in the blood temperature is recorded. A recent variation in design is the incorporation of a heating coil on the catheter (30cms from the tip, residing in the atrium area) which eliminates the cold fluid bolus, a major factor in human technique variation.
By attaching both the injector site and the ventricular thermistor to a small computer, the thermodilution curve can be plotted. If details about the patient's body mass index (size); core temp, Systolic, diastolic, central venous pressure CVP (measured from the atrium by the third lumen simultaneously) and pulmonary artery pressure are input, a comprehensive flow vs pressure map can be calculated.
In crude terms, this measurement compares left and right cardiac activity and calculates preload
Preload
In cardiac physiology, preload is the end volumetric pressure that stretches the right or left ventricle of the heart to its greatest geometric dimensions under variable physiologic demand...
and afterload
Afterload
Afterload is the tension or stress developed in the wall of the left ventricle during ejection. Following Laplace's law, the tension upon the muscle fibers in the heart wall is the product of the pressure within the ventricle, multiplied by the volume within the ventricle, divided by the wall...
flow and pressures which theoretically if stabilized or adjusted with drugs to either constrict or dilate the vessels to raise or lower the pressure of blood flow to the lungs, respectively, in order to maximize oxygen for delivery to the body tissues.
The ability to record results is not a guarantee of patient survivability. The true art remains with the consultant physician or intensivist in balancing fluid load, so much so that the introduction of a balloon catheter, which is usually yellow, has been nicknamed "The kiss of the yellow snake".
Pharmacotherapy lumens
Modern catheters have multiple lumenLumen (anatomy)
A lumen in biology is the inside space of a tubular structure, such as an artery or intestine...
s — five or six are common — and have openings along the length to allow administration of inotropes and other drugs directly into the atrium. Drugs to achieve these changes can be delivered into the atrium via the fourth lumen, usually dedicated to medication. Common drugs used are various inotropes, nor-adrenaline or even atropine
Atropine
Atropine is a naturally occurring tropane alkaloid extracted from deadly nightshade , Jimson weed , mandrake and other plants of the family Solanaceae. It is a secondary metabolite of these plants and serves as a drug with a wide variety of effects...
. A further set of calculations can be made by measuring the arterial blood and central venous (from the third lumen) and inputting these figures into a spreadsheet or the cardiac output computer, if so equipped, and plotting an oxygen delivery profile.
SvO2 measurement
One further development in recent years has been the invention of a catheter with a fiber-optic based probe which is extended and lodged into the ventricle wall providing instant readings of SvO2 or oxygen saturation of the ventricle tissues. This technique has a finite life as the sensor becomes coated with protein and it can irritate the ventricle via the contact area.Alternatives
Various other techniques have largely relegated the PA catheter to history, e.g. the lithium dilution technique; the external bio-resistance monitor or the very simple and reliable technique of esophogeal doppler measurements of the descending aorta.Complications
The procedure is not without risk, and complications can be life threatening. It can lead to arrhythmias, rupture of the pulmonary artery, thrombosisThrombosis
Thrombosis is the formation of a blood clot inside a blood vessel, obstructing the flow of blood through the circulatory system. When a blood vessel is injured, the body uses platelets and fibrin to form a blood clot to prevent blood loss...
, infection
Infection
An infection is the colonization of a host organism by parasite species. Infecting parasites seek to use the host's resources to reproduce, often resulting in disease...
, pneumothorax
Pneumothorax
Pneumothorax is a collection of air or gas in the pleural cavity of the chest between the lung and the chest wall. It may occur spontaneously in people without chronic lung conditions as well as in those with lung disease , and many pneumothoraces occur after physical trauma to the chest, blast...
, bleeding
Bleeding
Bleeding, technically known as hemorrhaging or haemorrhaging is the loss of blood or blood escape from the circulatory system...
, and other problems.
Controversy
The benefit of the use of this type of catheter has been controversial. Therefore many clinicians minimize its use. .Evidence of benefit
Several studies in the 1980s seemed to show a benefit of the increase in physiological information. Many reports showing benefit of the PA catheter are from anaesthetic, and Intensive Care settings. In these settings cardiovascular performance was optimized thinking patients would have supra-normal metabolic requirements.Evidence of harm or lack of benefit
Contrary to earlier studies there is growing evidence the use of a PA catheter (PAC) does not necessarily lead to improved outcome. The following explanations have been advanced. One explanation could be that nurses and physicians were insufficiently knowledgeable to adequately interpret the PA catheter measurements. Also, the benefits might be reduced by the complications from the use of the PAC. Furthermore, using information from the PAC might result in a more aggressive therapy causing the detrimental effect. Or, it could give rise to more harmful therapies (i.e. achieving supra-normal values could be associated with increased mortality).Utility of Pulmonary Artery Catheterization
Doctors Swan and Ganz should be recognized further for this important and unique advance from the 1970s. This interpretation of Adolph Ficks' formulation for Cardiac OutputCardiac output
Cardiac output is the volume of blood being pumped by the heart, in particular by a left or right ventricle in the time interval of one minute. CO may be measured in many ways, for example dm3/min...
by time/temperature curves is an expedient but limited and invasive model of right heart performance. It remains an exceptional method of monitoring volume overload leading to pulmonary edema in an ICU setting.
Noninvasive Echocardiography
Echocardiography
An echocardiogram, often referred to in the medical community as a cardiac ECHO or simply an ECHO, is a sonogram of the heart . Also known as a cardiac ultrasound, it uses standard ultrasound techniques to image two-dimensional slices of the heart...
and pulse-wave cardiac output monitoring are concordant with (and much safer) if not better than invasive methods defining right and left heart performance. The advent of MRSA and similar hospital based catheter infections now clearly limits the utility of this type of invasive cardiac ICU intervention.