Pulmonary Artery Catheterization

Anatomy and Physiology

Insertion of the catheter from one of the main central veins (subclavian, internal jugular, femoral) traverses into the superior or inferior vena cava and reach the right atrium. From the right atrium through the tricuspid valve, the catheter reaches the right ventricle. From here the catheter is advanced to the right ventricular outflow tract and then to the pulmonary artery after getting across the pulmonary valve. The tip of the catheter lays into the main pulmonary artery, where the balloon can be inflated and deflated for measurement of pressures. Balloon can be inflated here to obtain pulmonary capillary wedge (or occlusive) pressure which gives an indirect assessment of left sided filling pressures.

During the placement of the catheter, due to the transducer that is in the catheter, a pressure waveform can be seen in the monitor. Each section of the right heart anatomy has a distinctive pattern that can help to assist or helps to determine where is the catheter tips.

Indications

The most frequent indications for placement of a pulmonary artery catheter are the following[2][3]:

• Evaluation or diagnosis of pulmonary hypertension
• Distinduishing etiology of shock based on mixed venous oxygen saturation (SvO2) measurement such as in septic or cardiogenic shock[4]
• Assessment of volume status in severe shock[5]
• Evaluation of pericardial illnesses such as cardiac tamponade or constricitve pericarditis
• Assessment of right-sided valvular disease, congenital heart disease, cardiac shunts, when surgical repair is planned

Contraindications

Contraindications for placement of right heart catheterization are[6]:

• Insertion of the catheter through a site where is an active infection
• Presence of a Right sided ventricular assist device
• Lack of consent

A relative contraindication is the presence of left bundle branch block. If this is the case, due to the risk of right bundle branch block during catheter insertion, external or transvenous pacer should be placed at the moment of the procedure to prevent complete heart block.

Equipment

A Swan-Ganz catheter or right heart catheter is a quadruple-lumen catheter with a thermodilution sensor that is attached to a pressure transducer outside the body, with this transducer, is possible to determine the central vein pressure, right atrial pressure, right ventricular pressure, and pulmonary artery pressure[7].

The catheters size range from 60 to 110 cm in length and 4F to 8F in caliber

Each of the 4-lumen is placed in a specific distance through the length of the catheter, and each of them has a specific function, as explained[7]:

• The blue lumen or CVP port represent the right atrial lumen. Ii is at 30 cm from the tip of the catheter and rests within the right atrium. It is the proximal port and can be used for infusion. This port can assess central venous pressure (CVP) and right atrial pressure.
• The white or clear lumen terminates close to the prior lumen, at 31 cm from the tip of the catheter and lies in the right atrium. This port is used for infusion.
• The yellow lumen or PA distal is the pulmonary artery lumen is the distal port at the tip of the catheter. This port does the measurement of the pulmonary artery pressure. Mixed venous can be drawn from this port too.
• The thermistor is a red/white connector that consists a temperature-sensitive wire that terminates 4 cm proximal to the tip of the catheter. The terminal portion of the wire is called the thermistor bead, and it rests in a main pulmonary artery when the catheter tip is positioned correctly. The connection of the thermistor port to cardiac output (CO) monitor allows determination of a CO using thermodilution.
• The red port is the balloon port. Air is introduced to inflate the balloon and removed when needs to be deflated.
• The pulmonary artery catheter has a balloon that can be inflated and helps the clinician place the tip of the catheter in the pulmonary artery. 
• Within the catheter, there are black lines that help to measure the length of the catheter. One thin line is 10 cm, and a thick black line indicated 50 cm.

Preparation

Preparation for the pulmonary artery catheter is similar for the placement of every invasive procedure.

Verbal consent is necessary before the procedure. Detail explanation of the procedure, risk, and benefits need to be done before starting the procedure.

Selection of the site of insertion of the catheter needs to be selected before starting the procedure. Especial consideration needs to be taken when selecting the site of insertion as skin or site infection, prior vein thrombosis or anatomical abnormalities to prevent complications. Proper catheter selection according to the insertion site is necessary.

Sterile barriers and techniques need to be done during the procedure. Proper cleaning of the site of insertion and draping of the patient is necessary. Also, the person doing the procedure needs to be wearing protective equipment and sterile barrier as sterile gloves, mask, and surgical gown.

Pulmonary artery catheterization can be done under fluoroscopy (most common) or at the bedside with use of ultrasound and echocardiography for catheter placement.

Complications

Complications related to catheter placement are similar to the placement of central catheter placement[8]. Infection of the site of insertion can occur. 

Pneumothorax or hemothorax can be a complication after insertion when the catheter is placed in the subclavian vein.

Air embolism caused by entrainment of air from the infusion ports.

Complications related to catheter insertion include the occurrences of atrial or ventricular arrhythmias due to irritation or contact of the catheter with the cardiac walls[9].

Valve rupture or cardiac wall perforation can occur but it is rare.

Misplacement of the catheter can occur due to looping of the catheter in the right chambers. This can be prevented with the placement of the catheter under fluoroscopy and paying attention to the waveforms in the monitor.

Vessel rupture can happen at the moment of balloon inflation into the pulmonary artery. Pulmonary artery perforation, pseudoaneurysm formation, and rupture can develop and has a 30% to 70% mortality[10].

Pulmonary infarction can occur when the balloon is inflated for long period or migration to the catheter to the distal branches.

Thromboembolism can also occur secondary to inflammation or infection of the catheter that acts as a nidus for thrombus.

Clinical Significance

As mentioned before, placement of the PAC helps for diagnosis of multiple conditions[2][3].

PAC can help to determine causes of shock, as cardiogenic versus other causes as septic shock or distributive shock by obtaining SvO2

PAC is used to determine the cause of pulmonary hypertension for proper treatment after classification in the different groups of pulmonary hypertension.

PAC can help to determine the intracardiac pressurea and valvular abnormalities.

PAC also helps to determine intracardiac shunts and to determine hemodynamic state before the procedure.

PAC is an important procedure for diagnosis and management of different conditions and despite the underuse of this procedure, still useful.

PAC can be used to estimate pulmonary capillary wedge pressure to give indirect assessment of left sided filling pressures.

Enhancing Healthcare Team Outcomes

Pulmonary artery catheterization was once frequently done in ICU patients for various reasons. While a good technique for some patients, pulmonary artery catheterization is now being replaced by echocardiography, which has a lower morbidity than the pulmonary catheter. Pulmonary artery catheterization requires ICU nurses as part of the interprofessional team for insertion and monitoring. The technique is also associated with complications. Echo can be done at the bedside without the need for X-ray or fluoroscopy.