Pulmonary Artery Occlusion Pressure - An Overview

Introduction:

Pulmonary artery occlusion pressure is also known as pulmonary capillary wedge pressure (PCWP) and is commonly used to measure the left ventricular filling of the heart. It depicts the left atrial pressure and evaluates mitral valve function. Catheterization of the right side of the heart is still important for the diagnosis and treatment of patients with suspected pulmonary hypertension (PH) and selected cases of heart failure.

How Is Pulmonary Artery Occlusion Pressure Measured?

Pulmonary artery occlusion pressure is determined by inserting a Swan-Ganz catheter which is a multi-lumen balloon-tipped catheter, into a central vein and progressing it into a branch of the pulmonary artery. The balloon is subsequently inflated, occluding the branch of the pulmonary artery and providing a pressure reading comparable to that of the left atrium.

What Is Right Heart Catheterization (RHC)?

The right heart catheterization (RHC) operation is invasive and needs to be done with care. The process and its uses have significantly expanded. Although RHC was often used in the past, its usefulness in routine practice has been reduced due to the failure of several trials to demonstrate any benefit in patients with severe heart failure or cardiogenic shock. RHC is still a crucial tool for the diagnosis, prognostic assessment, and treatment of patients with suspected pulmonary hypertension and a subset of patients with heart failure.

What Are the Indications and Contraindications For Pulmonary Artery Occlusion Pressure?

• Indications

1. Calculation of the pulmonary artery occlusion pressure.

2. To help in the distinction between cardiogenic and noncardiogenic pulmonary edema.

3. To differentiate between various shock types.

4. To measure important hemodynamic parameters and evaluate treatment response.

5. For the verification of the pulmonary arterial hypertension diagnosis.

6. To determine the extent of the mitral stenosis (blockage).

• Contraindications

1. Abnormalities of the tricuspid or pulmonary valve.

2. Endocarditis on the right side of the heart.

3. Right-sided heart tumors or other tumors.

4. Left bundle branch block.

5. Refusal to provide consent by the patient.

6. Heart block.

What Is the Equipment Used to Measure Pulmonary Artery Occlusion Pressure?

The length and caliber of the Swan-Ganz catheter are typically 60 to 110 cm and 4 to 8 Fr, respectively. It bears the names of its creators, William Ganz and Jeremy Swan. The majority of PA catheters contain four distinct lumens, each of which performs a specific task.

• Right Atrial Pressure - It is measured using the proximal lumen, sometimes known as the blue port. The administration of drugs is another purpose for it. A second lumen may be present in some PA catheters used for medication infusion. At the distal end of the catheter, in the pulmonary artery, is the distal lumen, also known as the yellow port. It is used to collect a mixed venous sample and monitor PA pressures.

It is not advisable to introduce medications or infusions into this port. For balloon inflation and deflation, the red port is used. About 2 cm separates the balloon from the catheter's distal end. A 1.5 ml syringe is included with each PA catheter and is used to inflate or deflate the balloon. By following intracardiac blood flow, the inflated balloon aids in guiding the catheter from the right atrium into the PA. The inflated balloon aids in calculating PCWP as well. The pulmonary artery's core temperature is determined using temperature or a thermistor. This aids in the thermodilution method of measuring cardiac output.

What Is the Technique to Measure Pulmonary Artery Occlusion Pressure?

• Preoperative Evaluation - It is crucial to take a time-out before beginning any treatment. The medical staff carrying out the procedure should do the following:

1. Double-check the patient's information.

2. Confirm the procedure and location.

3. Obtain the patient's consent.

4. Ensure normal test results.

5. Evaluate the patient's prescriptions.

6. Make sure the right people and equipment are at the patient's bedside.

An ultrasound is often used to identify the internal jugular vein and guide the needle. In order to validate the vessel's patency and make sure there are no thrombi inside the vascular lumen, the ultrasound also aids in determining the position of the neighboring artery. Imaging guidance can also be carried out without an ultrasound.

• Procedure - The region is cleaned with an antiseptic solution as the initial phase of the process, and the patient is draped to provide a sterile working environment. A vascular probe is used to confirm the vessel's location once more. With the help of the given needle, the central vein is then pierced, and a guidewire is then inserted using the Seldinger procedure (a procedure done to obtain safe access to the central vein) The position of the guidewire inside the vein may be verified using ultrasonography. The needle is taken out when the guidewire's placement has been verified.

Next, a 3 to 4-mm incision is made with a scalpel blade very next to the guidewire to guarantee a straightforward approach. The guidewire should not be cut, so that must be taken care of. Over the wire and into the vein, an 8.5 Fr dilator with an introducer sheath is placed. The introducer sheath should remain in place while the wire and dilator assembly are withdrawn as a single unit.

The pulmonary artery (PA) catheter is introduced through the introducer sheath and progresses up to 20 cm once it is in place. This should position its distal tip within the right atrium, which a right atrial pressure waveform on the monitor can confirm. The 1.5 mm syringe is used to inject air into the balloon after the location inside the right atrium has been determined. The right ventricle and pulmonary artery are both reached after the catheter has been advanced.

A PCWP or pulmonary artery occlusion pressure may now be measured after acquiring the necessary PA pressures. To accomplish this, carefully inflate the balloon while keeping an eye on the display. Only enough air is pumped into the balloon for the PA pressure waveform to transition into a wedged waveform. The artery distal to the catheter and the pulmonary vein are separated by a static column of blood while the balloon is inflated. The PCWP, sometimes referred to as post-capillary pressure, is an approximate measurement of the pressure in the left atrium.

• Post-Procedure - A chest X-ray should be requested after the procedure to confirm the catheter's location and look for any problems. The mediastinal shadow is often where the tip of the PA catheter is located, and it should not protrude further than 2 cm from the hilum.

Conclusion:

A reliable substitute marker for left atrial pressure is pulmonary artery occlusion pressure. Its measurement is useful for determining the severity of left ventricular failure and the extent of mitral valve stenosis. The doctor can adjust the dosage of diuretic medications and other medications used to lower pulmonary venous and capillary pressure, hence lowering pulmonary edema, by evaluating pulmonary artery occlusion pressure. As a result, it can also direct therapeutic effectiveness.