Simple Method to Monitor Pulmonary Artery Pressure in Infants After Cardiac Operations Charles A. Dietl, MD, and Albert0 R. Torres, MD Department of Cardiothoracic Surgery, Geisinger Medical Center, Danville, Pennsylvania; and Institute of Cardiology and Cardiovascular Surgery, Hospital Guemes, Buenos Aires, Argentina

Intraoperative placement of catheters to monitor pulmo- nary artery pressure and cardiac output by oximetry can easily be accomplished under direct vision. The insertion through a saphenous vein cutdown assures a much safer removal, eliminating the risk of bleeding, tamponade, and catheter entrapment.

(Ann Thoruc Surg 1992;54:580-1)

nfant:: and children with congenital heart defects and I severe pulmonary hypertension are often at risk of development of pulmonary hypertensive crisis during their immediate postoperative period [ 11. These episodes, which may be fatal, require urgent recognition and treat- ment with hyperventilation and vasodilators, preferably infused directly into the pulmonary artery (PA) [2]. There- fore, continuous monitoring of the PA pressure after operation is beneficial in all infants and children with severe Flulmonary hypertension, especially if the pulmo- nary vascular resistance is elevated [l-31.

The purpose of this report is to describe a different approach for insertion of PA pressure and oximetric catheters, and the rationale for its routine clinical applica- tion in pediatric patients with severe pulmonary hyper- tension.

Technique

Under general endotracheal anesthesia, after insertion of venous and arterial lines, the skin is widely prepared from the chin to the knees, and both groins are included in the sterile area. Before sternotomy, a small transverse incision is performed below either groin. The saphenous vein is dissected, and usually a branch of adequate size can be used, avoiding permanent ligation of the saphenous vein (Fig 1). The length of the catheter is measured from the suprasternal notch to the groin, and marked at this level (see Fig 1). The catheter is then introduced and secured in place, with the mark coinciding with the skin incision in the groin. The instruments used in the groin are dis- carded, and the operation proceeds as usual, through a median sternotomy.

The catheter tip is usually found inside the right atrium or the superior vena cava. It may be retracted outside the right atrium until the intracardiac repair is completed.

- Accepted for publication April 22, 1992.

Address reprint requests to Dr. Dietl, Department of Cardiothoracic Surgery, Geisinger Medical Center, Foss-8, Danville, PA 17822-1343.

After air is evacuated from the left heart chambers, the catheter tip is placed under direct vision inside the main PA (Fig 2).

We have used two types of catheters: Intracath (Deseret Medical Inc, Sandy, UT) 19-gauge 12 inches long for infants (catalog no. 3374) or 16-gauge 24 inches long for children (catalog no. 3182), for continuous monitoring of PA pressure; and Opticath (Abbott Laboratories, North Chicago, IL) 4F 40 cm long (model U-440, catalog no. 50404), for continuous monitoring of the oxyhemoglobin saturation and the PA pressure.

The catheters were flushed before insertion, and pa- tency was maintained with a continuous drip of 500 units of heparin in 500 mL of D5W at 3 pg/min. In most cases, a vasodilator was infused postoperatively into the pulmo- nary artery through this catheter, which was usually removed within 2 to 5 days.

Clinical Experience and Results

Between September 1980 and August 1988, a total of 101 pediatric patients with severe pulmonary hypertension (>75% of systemic pressure) underwent intracardiac re- pair of their congenital heart defects. Their ages ranged from 2 days to 8 years (mean, 1.5 years); there were 65 infants and 36 children. They were divided into three groups, depending on the method used to monitor the PA pressure. In group A, among 21 patients without a PA catheter, there were 8 deaths (38.1% mortality), 5 of which were sudden, most likely due to a pulmonary hyperten- sive crisis. In group B, a transinfundibular PA catheter was placed in 19 patients, with 4 deaths (21.0% mortality), 1 of them caused by a pulmonary hypertensive crisis and 1 due to cardiac tamponade after withdrawal of the PA catheter. Group C consisted of 61 patients in whom a PA catheter was introduced through the saphenous vein approach described in this article. There were 7 deaths (11.4% mortality), 4 of them related to a pulmonary hypertensive crisis.

In our present series, a postoperative pulmonary hyper- tensive crisis occurred in 35 patients, 15 of whom died, including 10 patients who died directly as a consequence of intractable pulmonary vasoconstriction during the early postoperative period: 5/8 (62.5%) in group A, 116 (16.6%) in group B, and 4/21 (19.0%) in group C. Thus, a postop- erative pulmonary hypertensive crisis can be managed more effectively in patients in whom the PA pressure is continuously monitored ( p < 0.05).

Catheter-related complications occurred in 7 patients in

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Ann Thorac Surg 1992;54:580-1

HOW TO DO IT DIETL AND TORRES 581 PULMONARY ARTERY PRESSURE MONITORING

Branch of saphenous vein

PA catheter

. Femoral vein \

" PA catheter /- t.Yb

Fig 1. Catheter introduction in branch of saphenous vein (insert) and measurement of catheter length from groin ( A ) to suprasternal notch (B). (PA = pulmonary artery.)

whom a transinfundibular catheter was placed (group B), including 5 patients who had profuse bleeding after PA catheter withdrawal, requiring blood transfusion (inci- dence 26.3%), and another 2 patients in whom cardiac tamponade developed, 1 of whom died (5.2% mortality). Because of the morbidity associated with the transin- fundibular approach, we decided to abandon this method. In contrast, since we introduced the saphenous vein approach in February 1984, no catheter-related com- plications were observed in any of our patients ( p < 0.001). There were no instances of inferior vena cava

PA catheter

PA catheter Fig 2. Placement of catheter tip inside the main pulmonary artery (PA) under direct vision. ( IVC = inferior vena cava; SVC = supe- rior vena cava.)

thrombosis or sepsis associated with our technique, but we recognize that they may occur.

Statistical analysis was determined using the x meth- odology.

Comment Continuous postoperative monitoring of the PA pressure is recommended in all infants and children with reversible pulmonary hypertension, because extremely rapid clinical deterioration may occur secondary to acute pulmonary vasoconstriction [l]. Most of the pulmonary hypertensive crises occur during weaning from the respirator [l]. When these episodes are identified, a fatal outcome may be prevented by administering tolazoline hydrochloride di- rectly into the PA [2].

Most authors recommend inserting a catheter through the right ventricular infundibulum [3, 41. However, there is a small but significant morbidity associated with this procedure [3]. Serious bleeding may occur upon catheter removal, requiring blood transfusion in up to 43% of the patients [3]. In some cases, prompt reexploration is indi- cated to control the hemorrhage, or to relieve cardiac tamponade [3, 41. The overall mortality rate related to catheter extraction is relatively low, ranging from 0.06% [4] to 2.2% [3], but worthy of consideration. Other re- ported complications include retention or fracture of the catheter tip, which may also require reexploration [3, 41. To prevent these serious complications, we introduced in 1984 a simple and safer method for placement of pressure monitoring and oximetric catheters in the PA through a saphenous vein cutdown. We have also used this ap- proach for placement of left atrial monitoring lines, across a patent foramen ovale, similar to a technique described by McNicholas and Niguidula [5].

We are very grateful to Lisa Peiialver, BA, AMI, for providing the illustrations, and to Beth Landis, BS, for the statistical analysis.

References 1. Rabinovitch M. Problems of pulmonary hypertension in chil-

dren with congenital cardiac defects. Chest 1988;93:119S26S. 2. Jones ODH, Shore DF, Rigby ML, et al. The use of tolazoline

hydrochloride as a pulmonary vasodilator in potentially fatal episodes of pulmonary vasoconstriction after cardiac surgery in children. Circulation 1981;64(Suppl 2):134-9.

3. Wheedon D, Shore DF, Lincoln C. Continuous monitoring of pulmonary artery pressure after cardiac surgery in infants and children. J Cardiovasc Surg 1981;22:307-11.

4. Gold JP, Jonas RA, Lang P, Elixson EM, Mayer JE, Castaneda AR. Transthoracic intracardiac monitoring lines in pediatric surgical patients: a ten-year experience. Ann Thorac Surg 1986;42: 185-91.

5. McNicholas KW, Niguidula FN. A technique for placement of left atrial monitoring line. Ann Thorac Surg 1983;35:56&9.