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Ann Thorac Surg 1998;65:336-339
© 1998 The Society of Thoracic Surgeons

Original Articles: General Thoracic

Thoracoscopic Lobectomy With Endoarterial Vascular Control: An Experimental Study in Swine

A. Alan Conlan, MD, Charles Hsi, MD, Babs R. Soller, PhD, Janice M. BelleIsle, BS, Thomas J. Vander Salm, MD

Division of Cardiac and Thoracic Surgery, University of Massachusetts Medical Center, Worcester, Massachusetts, USA

Accepted for publication August 21, 1997.

Dr Conlan, Division of Cardiac and Thoracic Surgery, University of Massachusetts Medical Center, 55 Lake Ave North, Worcester, MA 01655-0304 (e-mail: alan.conlan@banyan.ummed.edu).


   Abstract
Top
 Abstract
Introduction
 Material and Methods
 Results
 Comment
 Acknowledgments
 References
 
Background. Video-assisted lobectomy lacks vascular control and presents the potential for serious hemorrhage in a closed cavity. The use of a lighted, flow-directed balloon catheter in the pulmonary artery as an endovascular control device was evaluated.

Methods. A modified light-bearing Swan-Ganz catheter was placed in the left or right pulmonary artery using fluoroscopy. The lit catheter was identified easily through the arterial wall at thoracoscopy. Its inflation allowed the control of proximal blood flow as required. Fully thoracoscopic lobectomy was carried out by isolating and dividing the lobar branches of the pulmonary artery, the pulmonary vein, and the bronchus in anesthetized swine.

Results. Forty-two video-assisted anatomic lobectomies were completed in 30 pigs with balloon catheter control of the pulmonary artery. The balloon effectively controlled experimental hemorrhage caused by puncturing arterial branches (n = 4). It allowed the transection of unlooped lobar arteries (n = 42) and the main interlobar pulmonary artery (n = 3). Catheter displacement back to the heart occurred in 5 animals and balloon catheter technical failures occurred in 3.

Conclusions. The lighted, flow-directed balloon catheter was an effective means of avoiding acute hemorrhage and achieving vascular control in a swine lobectomy model.


   Introduction
Top
 Abstract
 Introduction
Material and Methods
 Results
 Comment
 Acknowledgments
 References
 
Pulmonary lobectomy is the current standard surgical approach for localized non–small cell lung cancer and certain benign disease states. It requires open thoracotomy and is a complex surgical procedure that necessitates significant operative experience, skill, and judgment. Recent advances in video optics and imaging and in thoracoscopic surgical instrumentation have opened new approaches to traditional pulmonary resection. Endoscopic surgical skill has improved and advanced markedly in the last 5 years. Series of minimal access and fully thoracoscopic pulmonary resections have been accomplished and published [1] [2] [3] [4] [5].

Concerns have arisen within the context of these surgical series [3] [4] [5] [6] [7]. Major hemorrhage resulting from pulmonary artery injury has been reported during limited access surgical dissection. Its occurrence demonstrates the lack of vascular control and is an important obstacle to thoracic surgeons who are considering adopting this new procedure [8].

For economic and humane reasons, the impetus toward minimal access pulmonary resection currently is strong [1] [2] [9]. It offers reduced morbidity and postoperative pain, early mobilization, and a shortened hospital stay [1] [3] [6]. Postoperative recovery is less morbid and an early return to work results. The ultimate surgical result achieved by minimal access or thoracoscopic methods is fully comparable with that of the open procedure [3] [4] [5] [6] [7] [9]. These appeals are presented strongly by the popular press and newspapers. A wave of public expectation fueled by this exciting new surgical technology is pressuring surgeons to adopt it.

This experimental surgical study was done to evaluate the performance and applicability of an endoarterial balloon vascular control unit. During endoscopic thoracic operations, the ipsilateral lung is defunctionalized by a double-lumen endotracheal tube or bronchus blocker. This results in a fully atelectatic, shrunken lung in a large cavity, providing an ideal setting for thoracoscopic evaluation and operation [8].

The concept of intermittent (as required) endovascular control of the pulmonary artery using a flow-directed balloon catheter is appealing. When intermittent vascular inflow occlusion is combined with double-lumen intubation, a fully defunctionalized lung is presented to the operating surgeon. We conducted this animal study to investigate the effectiveness and reliability of an endoarterial balloon catheter as a vascular control device during lobectomy and experimental pulmonary artery hemorrhage.


   Material and Methods
Top
 Abstract
 Introduction
 Material and Methods
Results
 Comment
 Acknowledgments
 References
 
All animals received humane care in compliance with the Principles of Laboratory Animal Care formulated by the National Society for Medical Research and the "Guide for the Care and Use of Laboratory Animals" prepared by the Institute of Laboratory Animal Resources and published by the National Institutes of Health (NIH publication 85-23, revised 1985).

Thirty-five pigs weighing 45 to 50 kg underwent anesthesia induction with intramuscular telazol (2.2 mg/kg), ketamine (1.1 mg/kg), xylazine (0.21 mg/kg), and atropine sulfate (0.05 mg/kg). Each animal was intubated and maintained under general anesthesia with a 1% gas flow of isoflurane with oxygen. A volume ventilator was used. The animal was placed on a heating pad to maintain body temperature at approximately 37°C. The ear vein was cannulated for administering Ringer’s lactate. Electrocardiogram leads were placed for monitoring the heart rate. An 8F catheter introducer was placed in the right femoral artery for obtaining arterial blood gas samples, and a micromanometer (MPC 500; Millar Instruments, Houston, TX) was inserted for monitoring systemic blood pressure.

Attention was turned to the animal’s neck. The internal jugular vein was exposed and a 9F to 10.5F catheter introducer was placed. The modified light-bearing, flow-directed balloon catheter was passed through the introducer using x-ray fluoroscopy. The pulmonary placement technique used was successful in every animal. To access the right main pulmonary artery, the flow-directed balloon was inflated in the outflow tract of the right ventricle, from which it was carried straight to the right side. To access the left pulmonary artery and the left lung, the balloon was deflated when the catheter lay in the outflow tract of the right ventricle and then was advanced rapidly to the point at which it engaged the left pulmonary artery and deflected to the left side. This placement technique was fully reliable.

A tracheostomy then was performed and a Univent (Fuji Systems, Japan) tube (6.5 to 7.0 cm) was placed. Using a flexible pediatric bronchoscope (Olympus, Melville, NY), the balloon was guided into the main bronchus on the side planned for operation. The animal then was placed in a lateral decubitus position and incisions were made for the placement of trocar ports. The lowest trocar port was in the eighth or ninth intercostal space in line with the scapular tip. This was the camera port. Two posterior ports, usually in the third and fourth intercostal spaces, were placed for surgical instruments. Two anterior ports, usually in the fifth or sixth and third or fourth spaces, were made for the introduction of retracting clamps.

Forty-two anatomic lobectomies were completed in 30 animals, 40 of which were on the left side (28 upper and 12 lower). Left upper lobectomy was chosen because of the marked similarities with the human upper lobe anatomy. Visualization was accomplished with a Dyonics wide-angle (110-degree) electronic endoscope (Smith & Nephew Endoscopy, Andover, MA). This system includes a 300-W xenon light source, a light guide, and a Dyonics digital image processor that provides image enhancement and line-scan doubling.

The endoarterial vascular control units were custom-modified from Swan-Ganz pulmonary artery catheters. Several versions of a 110-cm, 7.5F catheter were designed and built. The latex balloon was mounted 2.5 mm from the tip of the catheter and extended 1.5 cm along its shaft. When inflated with 10 mL of gas, the balloon had a diameter of 19 mm and a length of 2.5 to 3 cm. In some animals, longer balloons (6 cm) were evaluated. A single plastic optical fiber 0.030 in. in diameter was placed in the central lumen of the catheter and sealed within the distal tip. When connected to the endoscopic light source, the tip of the catheter was illuminated. In later versions of the catheter, all blood-contacting surfaces were heparin-bonded to minimize thrombus formation. Some catheters contained a soft-tipped angioplasty guidewire in a separate lumen.

Once full deflation of the lung had occurred, the lung was retracted to the right side of the hemithorax and dissection was begun beneath the azygous vein. Often, lymph nodes overlaid the pulmonary artery, and these were dissected free and removed. The fascia of the pulmonary artery was opened and the upper lobe branches were identified and also dissected free, allowing the passage of right-angled clamps around them. The light-bearing, flow-directed balloon catheter could be visualized directly through the wall of the artery (Fig 1). It was placed at or above the origin of the branches. The pulmonary artery branches were clipped distally to give control. The balloon was inflated and cessation of flow was confirmed using a Doppler probe. The branches then were divided without the benefit of proximal control. The proximal stump was observed for bleeding and control. Sutures or hemoclips were used to occlude these branch stumps on the main pulmonary artery when it was clear that control was good. The balloon then was deflated.



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  		A segment of the pulmonary artery (PA) is transilluminated, showing several lobar branches. (AO = descending aorta.)

 
The upper two or three branches of the pulmonary artery were dealt with in this manner. The fissure between the upper and lower lobes was dissected next to expose the stout lingular branch located there. The lighted balloon catheter was advanced down the pulmonary artery until it was positioned at the takeoff of the lingular branch. The lingular branch was clipped distally for control and then was transected abruptly, demonstrating proximal control by the endobronchial balloon. The lobe was elevated and dissected to expose the bronchus. The bronchus was transected with an endoscopic gastrointestinal anastomosis stapler. The superior pulmonary vein was dealt with either by staple division or by clamping and tying. This completed the lobectomy. The lobectomy specimen either was removed by enlarging one of the thoracoscopy ports or was morcellated to reduce its volume. The animal was euthanized at the end of the operation.


   Results
Top
 Abstract
 Introduction
 Material and Methods
 Results
Comment
 Acknowledgments
 References
 
Forty-two anatomic lobectomies were completed in 30 pigs using a light-bearing endoarterial flow-directed balloon catheter for intermittent vascular control. Forty lobectomies were left-sided (28 upper and 12 lower) and 2 were right-sided (1 upper and 1 medial). Before lobectomy, 4 animals had experimental pulmonary artery injury inflicted by a large needle or a scissors cut. This large hemorrhage was controlled easily by proximal inflation of the balloon device and compression of the distal vessel using an instrument-mounted sponge. Once the blood was cleared by suctioning, the laceration was visualized easily and controlled by tie, clip, or suture.

Twenty animals had 32 anatomic lobectomies completed with intermittent proximal balloon control during the division of the lobar arteries. The lobar branches were dissected free and distal control was achieved by clip application or tying. The balloon control device then was inflated and the lobar branches were divided, leaving the proximal stumps uncontrolled. Once control was verified by a period of observation, these lobar branch stumps coming off the main pulmonary artery were closed by double clipping or suture.

Ten animals had lobectomies completed with balloon control for part of the procedure. Technical factors prevented completion of the entire lobectomy with endovascular control: balloon displaced into the heart, 5; balloon leak/injury, 2; light failure, 1; balloon herniation, 1; and balloon catheter knot, 1.

The main interlobar pulmonary artery was transected under proximal balloon control in 3 animals. It provided stable and completely effective vascular occlusion, allowing suture of the wide-open vessel end using a 5-0 polypropylene (Prolene; Ethicon, Somerville, NJ) suture (Fig 2).



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  		The transected interlobar pulmonary artery is elevated by a forceps. The lit catheter tip is visible (arrow). (AO = descending aorta.)

 
Local thrombus formation on the balloon was noted in 3 animals after 4 to 6 hours of placement in the pulmonary artery. In later balloon catheter models that were heparin-impregnated, this was not observed.

During left upper lobectomy, placement of the balloon too far proximal in the left main pulmonary artery allowed herniation to occur back into the main pulmonary artery. In 3 animals, this was sufficient to block the origin of the contralateral pulmonary artery. This was readily apparent as a falling cardiac output with cardiac arrhythmias. This clinical phenomenon reversed rapidly once the balloon was deflated. Careful hemodynamic monitoring clearly is important during proximal balloon placement and inflation in the pulmonary artery.

Damage to the balloon itself within the artery may occur during suturing or clipping. This happened in 1 animal and required hemorrhage control by sponge pressure with an instrument until the chest was opened. To prevent this complication, the balloon should be kept above and away from the site of suturing and clipping.

Placement and stable function of the balloon on the side of operation presented a problem during this study. The end light on the flow-directed balloon catheter was clearly visible through the arterial wall, allowing easy and definitive localization (Fig 1). However, when the balloon was withdrawn from the side of operation and escaped back into the heart, replacement was not possible. To address this problem, we used a fine, long vascular wire inserted through the catheter as a balloon stent. Although this allowed reliable movement of the balloon in and out of the side of operation, visibility was diminished markedly. The wire held the lighted tip of the catheter away from the arterial wall and more central in the vessel. This resulted in a marked diminution in light intensity and difficulty in locating the balloon.

In 3 animals, the current prototype of the balloon was equipped with a metal tip. A rod-mounted magnet was inserted through a thoracoscopy port and allowed the balloon to be drawn up and down the pulmonary artery on the side of operation. This proved to be a most effective and simple device. It gave control of the balloon’s position to the operating surgeon.


   Comment
Top
 Abstract
 Introduction
 Material and Methods
 Results
 Comment
Acknowledgments
 References
 
The occurrence of major hemorrhage within a closed chest cavity is of serious concern to thoracic surgeons who are considering the use of minimal access or fully thoracoscopic lung resection procedures [3] [4] [5] [8]. The strongest argument against such operations is the lack of vascular control [6] [8]. Currently, surgeons use an average 8-cm utility thoracotomy incision that they may or may not retract [1] [2] [3] [4] [5] [6] [10] [11]. An instrument-mounted sponge is kept readily at hand for rapid insertion through this utility incision if major hemorrhage from the pulmonary artery, the pulmonary vein, or the lung parenchyma occurs. The chest then is opened rapidly in the usual manner to allow this to be dealt with [5] [9].

The concept and use of a pulmonary artery flow-directed balloon catheter is well established. The flow-directed Swan-Ganz catheter is used routinely in the intensive care unit setting, in critical monitoring situations, and during anesthesia, although its effectiveness in improving the outcomes of critically ill patients recently has been questioned [12]. Reported serious complications include arterial puncture, thrombus, and cardiac arrhythmias [13]. The consensus is that pulmonary artery catheters are beneficial for many critically ill patients [14]. Pulmonary artery balloon catheters likewise have been used to simulate pulmonary artery transection when high-risk patients with marginal lung function are being evaluated for pneumonectomy. Pulmonary artery catheters also have been inflated to control hemoptysis resulting primarily from backflow from the pulmonary artery system to the bronchial system during massive hemoptysis.

The premise of a flow-directed endoarterial balloon control device is that it can be inserted easily by the equivalent of a routine Swan-Ganz cervical insertion. Fluoroscopy is required for a few minutes during placement to ensure its location on the side of operation. The light-bearing catheter is readily visible through the wall of the pulmonary artery once thoracoscopy is underway and the vessel is exposed. The optimum balloon size in the pig pulmonary artery appears to be 3 cm. If the balloon catheter is inflated too proximally in the pulmonary artery, it may herniate back into the main pulmonary artery and block the origin of the contralateral pulmonary artery. This is recognized easily by its immediate hemodynamic effects and is relieved by deflating the balloon and introducing it further proximally.

We have found that moving the balloon on the side of operation by withdrawing the catheter at the neck is inaccurate. The catheter has significant dead length and its withdrawal produces no immediate movement in the lighted end within the lung. After the entire length of the catheter has been taken up, movement often is rapid and the balloon can be lost into the heart. We have evaluated metal-tipped, light-bearing balloons and found that they can be moved readily up and down the pulmonary artery on the side of operation using a rod-mounted magnet. This is a very simple procedure and provides the operating surgeon with better control of the location of the unit. The placement of a long, soft-tipped vascular guidewire through the balloon and into the distal pulmonary artery appears attractive but renders complex operation of the balloon control unit as a whole and adversely affects light transmission.

This experimental study demonstrated the effectiveness of an endoarterial lighted balloon control device for proximal vascular control in the pulmonary artery. It allowed the transection of unlooped and uncontrolled pulmonary artery lobar branches during fully thoracoscopic lobectomy. The light-bearing tip was easily visible through the arterial wall. The device offered immediate control of hemorrhage from experimental pulmonary artery injury.

This light-bearing endoarterial balloon vascular control device may progress to clinical application if its operation remains as simple as the insertion and management of a flow-directed Swan-Ganz catheter. It may provide a safety margin during minimal access and wholly thoracoscopic lung resection procedures, especially during the early operative experience. It may have further application when particularly unfavorable operative conditions are present, even during open lobectomy. These include extreme fibrosis and hazardous access to the pulmonary artery as a result of inflammatory or radiation fibrosis.


   Acknowledgments
Top
 Abstract
 Introduction
 Material and Methods
 Results
 Comment
 Acknowledgments
References
 
This project was supported in part by a grant from Smith & Nephew Endoscopy, Andover, Massachusetts.


   References
Top
 Abstract
 Introduction
 Material and Methods
 Results
 Comment
 Acknowledgments
 References
 

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