What Is a Swan-Ganz Catheter?

Swan-Ganz balloon catheter is a tool for measuring pulmonary artery pressure (PAP) and pulmonary capillary pressure (PCWP). The total length is 110cm, and there is a scale every 10cm. The balloon is about 1mm from the top of the catheter. It can be inflated with 0.8 to 1ml of air or carbon dioxide gas. The diameter of the balloon after inflation is about 13mm. Used to inflate or deflate the airbag. There is a lumen opening at the top of the catheter for pulmonary artery pressure monitoring. This is a dual-lumen cardiac catheter. The three-lumen tube is about 30 cm away from the top of the catheter and has another lumen opening, which can be used for right atrial pressure monitoring. If a thermistor probe is added 4cm away from the top, the cardiac output can be measured. This is a complete four-chamber balloon floating catheter.

Swan-Ganz floating catheter

Myocardial infarction,

The catheter is punctured through the elbow vein, femoral vein, internal jugular vein, and subclavian vein, and the catheter enters the right atrium, right ventricle, and pulmonary artery through the superior or inferior vena cava.

Transcatheter or femoral vein catheterization is relatively far from the heart, especially for re-used catheters, because of the relatively long soaking time in the blood flow in the body, the catheter becomes soft, and it is easy to bend and difficult to operate, making intubation Failure; if the catheter is used for intraoperative monitoring of some patients before major surgery, the anatomical position of the catheter here can make the operator and the guardian affect each other during the operation; such as the femoral vein catheter itself and postoperative Contamination opportunities for catheter maintenance are relatively increased. In view of the existence of these disadvantageous factors, clinicians rarely choose distal venous intubation, and prefer the internal jugular vein or subclavian vein catheterization. It is relatively smooth to insert the catheter into the bloodstream through this vein. The length of the catheter is almost half that of the distal venous catheter, and there is less chance of contamination, which is easy for clinical monitoring and care. However, the operator is required to have comprehensive skills and clear anatomical positions to avoid as many complications as possible. The first-time intubation is of course the most secure for the individual, and the venous blood path selected for the successful intubation may be the best.

The average distance from the placement of the elbow vein or femoral vein to the pulmonary artery was 55-65 cm, and the placement of the jugular and subclavian veins was 35.45 cm.

Preoperative preparation

1. Environmental preparation: The operation should be performed in a clean and ventilated cardiac catheterization operating room or ward. The ground is sterilized with 2 to 5% lysine water. The operating bed and unit can be irradiated with ultraviolet light for 30min.

Cardiac catheterization room setting: The cardiac catheterization room can be set up separately in the ICU. It is a single room of 16-20m2. The operation room is equipped with an operation bed. X-ray machine, ECG monitor, several RJ45 network ports are located beside the bed, defibrillation Machines, anesthesia machines, tracheal intubation items; oxygen and negative pressure air sources, blood pressure meters, stethoscopes, etc. are also essential items in the room. In addition, the cardiac catheterization room should also have post-sterilization intubation equipment and rescue drugs.

2. Item preparation: a sterile Swan-Ganz balloon floating catheter. Vein puncture needles, guide wires, dilators, surgical blades, and tee plates are soaked in alcohol for later use.

Twisted-pair network cable, bedside monitor.

Iodine, alcohol, gentian purple, cotton swabs, 5ml empty needle for spare.

Catheter package:

2 surgical gowns; 6 sterile hand towels;

1 rectangular treatment tray; 4 sterile gauze;

4 mosquito forceps; 1 mosquito forceps;

Back handle with tooth pliers; 1 handle;

1 Ke Ke pliers; 1 Alice pliers;

Needle and thread; 2 pairs of sterile gloves;

2 treatment bowls; 4 towel clamps;

4 yarn balls; 5ml and 20ml syringes;

1 long needle.

Note: The contents of the catheter package are complete, and the double-layered foreskin is autoclaved for future use.

3 Drug preparation: lidocaine, propranolol, nitroglycerin, epinephrine, atropine, diazepam, flumetasone, arrow poison, dopa gum, etc.

2% Procaine

Heparin solution configuration: Heparin 100mg / branch added 0. 1000ml of 9% physiological saline is equivalent to 12.5IU / ml. A 500ml bottle was drained from the IV line despite the internal air.

4 Patient preparation: supine position, head to one side, intubation site is clean.

Measure and record vital signs: Connect the monitor with twisted-pair network cable, blood pressure, heart rate, breathing frequency, consciousness, etc., and record them on the nursing record sheet.

The height was recorded in cm and the weight was measured in kg.

Calculate body surface area: It is defined as the area occupied by each person in space, and the unit is calculated in m2. Related indicators are height and weight.

(L) Calculation formula: body surface area (m2) = 0.006 × height (cm) + 0.0128 × weight (kg)-0.1529.

Surgical operation

Operators wear hats, masks, brush their hands, and perform aseptic surgery.

Internal jugular vein catheterization:

Internal jugular vein anatomy: The internal jugular vein continues from the sigmoid sinus and exits from the skull base. Initially on the outside of the internal carotid artery, followed by descending on the outside of the common carotid artery, it is enclosed in the carotid sheath with the vagus nerve between the arterial and vein. The lower end of the internal jugular vein is swollen and deeper. Under the cover of the sternocleidomastoid muscle, the root of the neck merges with the subclavian vein (Figure 20).

Operation steps: The patient lies on his back with his head turned to the left and his head lowered to 30 degrees. Use gentian purple to mark the triangle of the neck and position it at the midpoint of the top of the triangle.

There are two surgeons and one nurse under the stage.

Routine local skin disinfection, towel spreading, and infiltration anesthesia with 2% procaine.

The venous puncture needle, dilator, guide wire, blade, and tee plate (made by connecting three tees) after alcohol immersion were delivered under the synchronized table. Sterile Swan-Ganz catheter. Place in the sterile area of the opened catheter bag. Into the two treatment bowls, put appropriate amounts of alcohol and heparin saline.

The surgeon checks the cardiac catheter: the catheter should have a normal curvature, and should be discarded if it is obviously dead, otherwise it is very difficult to place the catheter. Use a 1ml syringe to draw air from 0.8 to 1ml, fill the balloon, and check the catheter balloon for leaks or the balloon to one side. If the balloon is broken or leaks slowly, replace the catheter. The balloon to the side may affect the monitoring value The accuracy should be noted.

After checking the available cardiac catheters, use a 20ml syringe to aspirate heparin saline to flush each lumen, and connect them to the tee plate. Exhaust the catheter and the gas in the tee before use.

Check whether the puncture needle, dilator and guide wire can be used together and rinse with heparin saline for later use.

Puncture method: the left index finger and middle finger of the operator touch the surface of the carotid artery and push it inward to leave the front edge of the sternocleidomastoid muscle. The needle is inserted at a 30-45 degree angle between the index finger and middle finger at the front edge and the frontal plane, and the needle points to the ipsilateral nipple toward the caudal side. After the puncture needle enters the skin and draws venous blood, the puncture is proved successful. After inserting the guide wire, the puncture needle is pulled out. The puncture port was slightly expanded with a wire guide, and the outer cannula was placed into the internal jugular vein using a dilator. Exit the guide wire and dilator, and then insert the cardiac catheter through the outer sleeve, so that the catheter quickly enters the cardiac cavity at a small distance.

Turn on the X-ray machine and trace the insertion position of the catheter until it enters the pulmonary artery. The balloon is inflated and the catheter enters the distal end of the pulmonary artery. After the balloon is deflated, the catheter quickly returns to the original pulmonary artery position, which proves that the position is good. After external fixation.

In actual work, some patients cannot move to the catheterization room due to their critical condition, or there is no X-ray equipment in the ward, so the Swan-Ganz catheterization method can be inserted blindly at the bedside, and the catheter can often be successfully placed.

The so-called blind placement of a bedside is to indirectly determine its position through the pressure waveform of the catheter in a certain heart, which requires certain basic knowledge and clinical experience.

When blindly intubating at the bedside, first connect the original tee plate of the cardiac catheter to the sensor, so that the pressure waveform of each heart cavity is directly displayed on the bedside monitor, and synchronous ECG monitoring is also required.

The inserted cardiac catheter first enters the right atrium via the superior or inferior vena cava. The pressure waveform in the right atrium appears on the monitor, and the blood flow is directed through the tricuspid valve into the right ventricle. . It passes from the pulmonary valve to the pulmonary artery and finally enters into the distal branch of the pulmonary artery. After the balloon was deflated, the catheter quickly returned to the pulmonary artery. When the catheter was confirmed to be in good position, a needle was applied to the skin to fix the catheter. The puncture site was covered with a sterile dressing and fixed with adhesive tape.

In short, the floating catheter enters the pulmonary artery by the thrust of the blood flow on the catheter balloon. Due to the geometric relationship between the very flexible and inflated balloon surface at the distal end of the catheter and the blood flow force, it achieves the maximum with a small balloon area. The floating force and easy to drift into the pulmonary arteries. And because the inflated balloon does not allow the tip of the catheter to exceed the surface of the balloon, the force acting on the top of the catheter is dispersed on the surface of the inflated balloon, thereby reducing the stimulation of the endocardium. Therefore, the Swan-Ganz catheter has the advantages of less ventricular arrhythmia, rapid placement into the pulmonary artery, and no X-ray fluoroscopy, and has become a standard bedside method for measuring hemodynamic parameters.

In addition, the subclavian vein is often selected as the blood flow channel for the Swan-Ganz tube. The similarity and difference with the internal jugular vein intubation is that the patient is lowered after taking the supine head. Due to its different anatomic location, the puncture needle can be directly venipunctured through the superior or inferior clavicle. After the venous blood is drawn, it is operated in sequence until the cardiac catheter is transported into the heart. The disadvantage is that there are many complications and it is directly related to the operator's surgical proficiency. For the first time intubation, the balloon floating catheter can also be inserted through the elbow vein incision. However, if the catheter is retained for a long time, it may easily cause superficial phlebitis, and it is generally not used as a catheterization channel.

Complications of inserting a floating catheter

1. Arrhythmia: It is a common complication that often occurs during intubation. Because the catheter tip contacts the myocardial wall or heart valve, it can prevent changes in electrocardiogram such as premature ventricular contraction and supraventricular tachycardia. Later, the premature ventricular contraction disappeared quickly. However, if severe cardiac rhythm disorders occur, such as ventricular tachycardia and ventricular fibrillation, the cardiac catheter should be removed immediately, and medical treatment and emergency treatment should be given.

Note: The ECG must be continuously monitored during operation, and the inserted catheter cannot be forced into if it encounters resistance. Patients with existing inadequate myocardial blood supply or heart disease may be given nitroglycerin 5mg before the day of surgery and given oxygen therapy. Those with arrhythmia were injected with lidocaine 50mg to prevent recurrence. Emergency medications are necessary by the patient's bed.

2. Catheter balloon rupture; common in repeated use of the catheter, caused by loss of balloon elasticity. After the balloon ruptures, the pulmonary artery embedded pressure index is lost, and the embolism may be caused by reinflating the balloon.

Note: The maximum amount of airbag inflation can not exceed 1.5ml. In clinical, airbags can be inflated with air, carbon dioxide gas or saline. However, due to the inconvenience of operation and difficulty of deflation of the latter two, it is rarely used. Those who find that the balloon is ruptured and do not need to remove the cardiac catheter for the time being should mark the end of the catheter and shift to avoid other people performing the balloon inflation test (especially when the position of the catheter seems to change).

3 Infection and thrombophlebitis: Due to the lack of strict aseptic operation during catheterization, incomplete disinfection of repeated catheters and contamination during catheter maintenance, direct bloodstream contamination can be seen in patients with clinically high fever, chills, and even sepsis. Thrombophlebitis often occurs in patients with peripheral venous catheters. It is closely related to the time of tube placement. The longer the time, the higher the incidence rate.

Note: the sterility requirements for intraoperative and postoperative operations must be emphasized, the treatment of used catheters should also be very strict, and the bacteria should be cultured regularly after disinfection. The wound at the skin cannula was changed once a day and kept clean and dry locally. Cardiac catheter indwelling time is preferably no more than 72h to prevent infection and thrombophlebitis.

4. Pulmonary embolism: due to the balloon inflated at the tip of the catheter is inserted into the pulmonary artery for a long time or caused by the catheter moving in the pulmonary artery multiple times.

Note: In addition to mastering certain skills during catheterization and the time required to inflate the catheter balloon, continuous balloon inflation is generally not recommended, and the average pulmonary artery pressure is used as a continuous clinical monitoring indicator, which indirectly reflects the pulmonary artery embedding. Pressure changes.

5. Catheter obstruction or pulmonary thrombosis: more common in patients with a history of embolism and hypercoagulable blood. Preventive anticoagulation therapy should be performed. Each lumen of the cardiac catheter is flushed with heparin saline once an hour, and the intracardiac pressure pattern is changed to keep the cardiac catheter open.

6. Pulmonary artery rupture: seen in patients with pulmonary hypertension and vascular wall degeneration, due to repeated movement of the catheter in the pulmonary artery and excessive inflation of the balloon. Care should be taken to maintain proper inflation in the balloon and closely monitor changes in pulmonary artery pressure.

7. Catheter twists and knots in the heart cavity: Occurs when the catheter is soft, pliable, and inserted into the vessel too long. It should be noted that the length of the catheter is inserted, and the pulmonary artery from the right atrium should generally not exceed 15 cm. Found distortion should exit. If it is knotted, you can insert the needle wire into the catheter to release the knot. If it does not work, you have to tighten the knot and pull it out slowly.

Maintenance of floating ducts

The floating catheter inserted in the heart cavity is of great value for assessing the state of circulatory dynamics. However, because the catheter is long and each lumen is very narrow, it is easy to cause embolism in the tube. In order to ensure the maximum effective use of the catheter, a heparin solution flushing device is necessary.

Heparin solution: 6250IU of heparin was diluted into 500ml of 0.9% physiological saline, so that each ml of the liquid contained 12.5IU of heparin.

Catheter flushing indications:

1. Cardiac pressure image is abnormal: The pressure wave is flattened, and the pressure value is significantly different from the previous value.

Another phenomenon of abnormal waveform is due to the change of catheter position. If the catheter exits the pulmonary artery, the monitor displays an image of right ventricular pressure, which is not due to lumen obstruction, and irrigation is not effective. The position of the catheter should be readjusted under aseptic procedures or confirmed by X-ray chest radiography.

2. Before each measurement of the complete set of hemodynamic indicators, to ensure the accuracy of the values, each lumen should be flushed once.

3 Routine maintenance catheter heparin solution is flushed once an hour. Methods: The same as arterial tube irrigation.

Note: The external rinsing device of the floating catheter is the most susceptible to contamination, especially the syringe used to rinse the lumen multiple times. Because the needle plug is frequently exposed to the air and directly operated by the medical staff, the chance of contamination is the most. In order to prevent the occurrence of bloodstream infections, the syringe should be replaced every day, and strictly speaking, it should be replaced every time after use.

The indirect flushing device is unreasonable, and in view of the economic conditions in our country, disposable syringes cannot be widely used, so we must find ways to minimize the occurrence of syringe contamination to extend its use time.

Method introduction: Pull the needle bolt apart. A sterile plastic bag was used to cover it from the tail, and the syringe was wrapped and fixed with adhesive tape so as not to affect the suction of heparin solution. Replace the syringe every 8-12 hours.

In the flushing operation, it is very common that the nipple end of the glass syringe is broken in the tee due to excessive manual force or angular deviation, which causes trouble to the nursing work and damages the tee and the syringe. This makes the choice of air gauges as much as possible in favor of plastic products, and this kind of syringe completely avoids the above-mentioned damage.

The external irrigation and pressure measuring device of the catheter should be tightly connected, otherwise it will easily cause blood back in the lumen and cause obstruction.

In the clinic, if the patient has high fever, chills and other manifestations, and he is highly suspected to be due to cardiac catheter pollution, he should remove the catheter immediately, perform bacterial culture of residual blood in the catheter, and give antibiotics for treatment.

Generally, the floating catheter is indwelled for 3 to 5 days, and it can be retained for 9 days or longer. However, the reliability of the pressure value of the catheter for more than 5 days is generally doubted. Catheters should be removed if thrombophlebitis or embolism occurs. The optimal time for catheter indwelling is 48-72h.

Hemodynamic pressure measurement

The direct indicators obtained from the Swan-Ganz balloon floating catheter were right atrial pressure (RAP), pulmonary artery pressure (PAP), pulmonary artery embedding pressure (PCWP), and cardiac output (CO). The indirect indicators obtained through formula calculation are pulmonary circulation resistance (PVR), systemic circulation resistance (SVR), work per stroke (SW), left ventricular work (LVSW), right ventricular work (RVSW), and cardiac index (CI ). If necessary, a mixed venous blood sample can be taken through a catheter, and the partial venous oxygen pressure (PvO.) Can be measured to indirectly understand the ventilation function.

method:

Pressure measuring device and catheter flushing device:

1. Adjust the zero point: make the sensor at the same level as the patient's heart, twist the tee to make the sensor communicate with the atmosphere. When the monitor pressure value is displayed as zero, it means that the zero point adjustment is completed.

2. Flush each lumen so that the sensor communicates with a lumen.

3 Prepare the cardiac output monitor, adjust it to the working state, and enter the patient's blood temperature and the external control ice water temperature. Repeatedly aspirate 10 ml of sterile ice-cold saline with a 10 ml syringe to access the end of the right atrial lumen catheter.

4 Push the ice salt water quickly within 4S clock, and press the cardiac output monitor at the same time, the machine will display the cardiac output value.

5. Simultaneously record PAP, PCWP, BP, HR, RAP.

PAP: measured by connecting the sensor to the lumen to the pulmonary artery.

PCWP: Based on the above, the catheter balloon was inflated, and the catheter drifted into the pulmonary capillaries.

RAP: measured by communicating the sensor with the lumen leading to the right atrium.

BP, HR: measured by conventional methods.

Floating duct now, past and future

The floating catheter was used in 1970, and it can be completed even within minutes of critically ill patients by the bed. Although it is not difficult to place these catheters, some training and experience are necessary in order to obtain reliable hemodynamic data and reduce the occurrence of complications through pulmonary artery intubation. Because balloon floating catheters have many advantages over traditional catheters, they are used in patients without indications and overused in intensive care units, leading to many complications and increased mortality.

Prospective randomized controlled studies report that, in most clinical situations, the routine use of floating catheters has no indications. These results are not surprising, as floating catheters are a means of diagnosis, not treatment. We obtained a large amount of non-negligible hemodynamic data by monitoring floating catheters in critically ill patients. In addition, we gain a wealth of clinical knowledge and experience in hemodynamics by directly measuring hemodynamics.

It should also be recognized that in spite of the increase and improvement of non-invasive imaging methods, the use of floating catheters to detect hemodynamics is necessary in some clinical situations, but only experienced doctors should complete this operation. Proper use of floating catheter monitoring has greatly improved our understanding of hemodynamics. It is misused, especially by relatively inexperienced operators, which can cause serious complications and even death.

Prospective randomized clinical trials have shown that routine use of floating catheters does not bring any benefit. However, floating catheters can still be used in many clinical situations.