All lumens of the catheter are flushed with heparinised saline and the distal (pulmonary arterial) lumen is connected to a pressure transducer. The balloon should be checked for proper inflation. This is performed by confirming the symmetry of inflation after injection of 1.5 mls of air and the absence of leaks by immersing the balloon in a small dish of sterile saline while inflated.

The catheter is manufactured with a natural curve. This curve should be positioned to facilitate passage through the tricuspid valve and right ventricular outflow tract. If the right internal jugular approach is used, the tip should be pointing at the 'nine' or 'ten o'clock' position before insertion into the sheath.

Once the catheter has been introduced into the indwelling 8.5 French sheath introducer, it should be advanced slowly to the 20cm mark. At this point the balloon should be inflated with 1.5 ml of air and inflation should be maintained by use of the balloon lock. If there is any question of the patient having an anatomical right-to-left shunt, CO2, rather than air, should be used for balloon inflation. The balloon must only be inflated with air or CO2 (never fluid) delivered by the volume-limited syringe which is supplied with the catheter.

If the patient is in a head-down posture, the patient should now be leveled. - Maintenance of a head-down posture during flotation is associated with a higher incidence of cardiac arrhythmias ¹ and a reduced likelihood of entry into the pulmonary artery.

After balloon inflation the catheter should be advanced slowly to allow the blood flow to direct the catheter through the cardiac chambers. A characteristic change in pressure waveforms will be seen as the catheter traverses the right atrium, right ventricle, and pulmonary artery.

If difficulty is experienced in making the transition from right atrium to right ventricle, it is most commonly due to indavertent passage of the catheter down the inferior vena cava. Very occasionally, failure of ventricular entry may be due to the presence of a right atrial membrane ².

The right ventricular pressure wave is characterised by a low diastolic pressure which approximates to the central venous pressure and which tends to rise progressively during the diastolic interval (Figure 1).

The transition to the pulmonary artery is characterised by the development of a dicrotic notch and a higher diastolic pressure which tends to fall progressively during the diastolic interval (Figure 2).

If difficulty is experienced in making the transition from right ventricle to pulmonary artery, slight reverse Trendelenburg position and right lateral tilt may facilitate passage of the catheter by elevating the right ventricular outflow tract thereby making flotation through the pulmonary valve more likely.

Elevation of the legs (or, if breathing spontaneously, hyperventilation) during ventricular transition may also facilitate the entry of the catheter into the pulmonary artery by producing a transient increase in venous return and therefore, flow through the right ventricle.

Once in the pulmonary artery, the catheter should be advanced slowly until pulmonary artery occlusion occurs (Figure 3).

At this point, the end-expiratory pulmonary artery occlusion (`wedge') pressure should be noted and the balloon deflated. Note that (like all intrathoracic pressures), the wedge pressure fluctuates with respiration. The balloon should now be slowly reinflated until the wedged trace reappears. If this occurs at a balloon volume of less than ~1.3 mls, the catheter should be withdrawn a centimetre or so until wedging only occurs at maximum (1.5ml) volume. (The simulator can be used to demonstrate this effect.)

The end-expiratory pressure should be recorded. If the patient is breathing spontaneously, this pressure will correspond to the 'peak' of the wedge pressure trace, whereas if ventilation is controlled, it will correspond to the 'trough'.

If, for any reason, the catheter is withdrawn, the balloon must be deflated before withdrawal. Valvular damage (see 'Miscellaneous Complications') may occur if this procedure is not followed ^{3, 4}.

If the right Internal Jugular approach is used, the right atrium is typically entered at 20 - 30cm, the right ventricle at 30-40cm and the pulmonary artery at 40-50cm. Occlusion usually occurs within 5 cms of entering the pulmonary artery.

(Video 4) shows the flotation process in detail.

Radiological confirmation of the position of the catheter is customary after insertion.

1. Keusch DJ, Winters S, and Thys DM The patient's position influences the incidence of dysrhythmias during pulmonary artery catheterization. Anesthesiology 70:582-584, 1989.

2. Yodfat UA. Right atrial membrane interfering with insertion of pulmonary artery catheter. Anesthesiology. Aug;93(2):576-8. 2000

3. Boscoe MJ, de Lange S: Damage to the tricuspid valve with a Swan-Ganz catheter. Br Med J 283:346, 1981.

4. O'Toole JD, Wurtzbacher JJ, Wearner NE, and Jain AC: Pulmonary-valve injury and insufficiency during pulmonary-artery catheterization. N Eng J Med 301:1167-1168, 1979.

Last edited on: 28/02/2001