Abstract

An 84-year-old male was scheduled for coronary artery bypass graft surgery under general anesthesia. During cardiopulmonary bypass, the leakage of blood into the syringe being used for balloon inflation and the thermistor connector of the pulmonary artery catheter (PAC) was detected. Resistance was encountered when trying to withdraw the PAC. A surgical suture of the right atrium cannulation was stitched to PAC and was immediately released. Early detection of surgical damage to PAC and recognition of the entrapped PAC by gently withdrawing it avoided possible life-threatening complications, including pulmonary air embolism, and the inevitable of resternotomy. Transesophageal echocardiography, chest radiography, and fluoroscopy can help confirm any postoperative surgical damage following closure of the sternum or while in the intensive care unit.

Keywords

complication; entrapment; pulmonary artery catheter;

1. Introduction

Pulmonary artery catheterization (PAC) is generally used to measure pulmonary artery pressure and cardiac output, and monitor hemodynamics during cardiac surgery and critical care. However, the insertion and manipulation of PAC during cardiac surgery can lead to rare but catastrophic complications, including direct pulmonary artery penetration,¹ pulmonary artery rupture,² and entrapment by knotting or involvement of the surgical sutures.³ Here, we report a case of an entrapped PAC by accidental concurrent stitching to a suture for the right atrium cannulation, which was detected early due to blood leaking into the syringe used for inflating the PAC balloon and the thermistor connector.

2. Case report

An 84-year-old male (78 kg, 165 cm) of American Society of Anesthesiologists (ASA) physical status III presented with angina pectoris and was admitted for coronary artery bypass graft (CABG) surgery subsequent to coronary catheterization. He had sustained an inferior wall myocardial infarction 8 years ago and was under regular medication. Preoperative transthoracic echocardiography revealed dilated right atrium, dilated left atrium, moderate mitral regurgitation, moderate tricuspid regurgitation, and akinesia of the anterior wall with poor systolic function (15% ejection fraction).

Induction of anesthesia was performed smoothly under protocol monitoring. After endotracheal intubation, an 8F flow-directed thermodilution continuous cardiac output pulmonary artery catheter (PAC) (Hospira, Lake Forest, IL, USA) was inserted through an 8.5F percutaneous sheath introducer (Arrow International, Reading, PA, USA) that was then positioned into the right internal jugular vein.

The catheter was successfully positioned at the 50-cm mark under the surveillance of transesophageal echocardiography (TEE). The pulmonary artery pressure, as measured, demonstrated normal waveform morphology. Then, the PAC was withdrawn to the 45-cm mark for fixation before cannulation of the right atrium. During cardiopulmonary bypass (CPB), blood was noted in the syringe used for balloon inflation and around the thermodilution port of the PAC (Fig. 1). Considering the possibility of catastrophic hemorrhagic shock following the removal of an undetected entrapped PAC, as reported by our colleagues,³ the anesthesiologist in charge attempted to gently advance and withdraw the PAC in order to let it loose. Resistance was encountered, and the stretching and pulling of the purse-string suture of the cannulation at the right atrium was confirmed by upon manipulation the surgeon. The previous stitch was excised and replaced with a new purse-string suture, and the PAC catheter was then withdrawn smoothly. Close inspection of the removed PAC revealed a 6-0 polysorb thread that had been tied in with the atrial cannulation at the 11-cm mark from the PAC tip, where bubbles popped out after the injection of air by the balloon syringe (Fig. 2). A new PAC was inserted and the operation proceeded without further complications. The patient was transported to the intensive care unit after surgery and discharged without sequelae.

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Fig. 1. Accumulation (0.9 mL) of blood in the syringe used for balloon inflation and the thermistor connector of the thermodilution continuous cardiac output pulmonary artery catheter during cardiopulmonary bypass surgery.

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Fig. 2. An air bubble (left) emerged from the suture site at 11-cm mark of the removed pulmonary artery catheter that was used to inflate the balloon with a syringe. The cross-section (right) at 11 cm of a thermodilution continuous cardiac output pulmonary artery catheter demonstrates the penetration of the stitch through the lumen for inflation at the tip (1) and the thermistor connector at 5 cm (2). The spared lumens cannot cause external blood leakage when the pulmonary artery port tracks distally to the tip (3), the lumen for distal central venous port (4) ends at 13 cm, the lumen for thermal coil (5) locates between 13 and 30 cm, and the proximal central venous port (6) ends at 30.5 cm.

3. Discussion

In this case, entrapment of the PAC was detected early by the presence of blood in the balloon syringe and the thermistor connector, and bleeding was resolved by the removal of a stitch out of the right atrium that was tied to the PAC. Potential catastrophic complications, such as pulmonary air embolism, rupture-induced hemorrhagic shock, and inevitable resternotomy, were thus avoided.

The blood that was detected in the syringe could have trickled directly into a ruptured balloon, which is caused by overinflation or threading of the PAC through the sheath; this can be simply verified by reinflating the balloon after withdrawing the tip of the PAC into a transparent plastic bag. Besides, direct penetration of PAC by perioperative scalpel has been reported,⁴ in addition to surgical suture at the cannulation site of the inferior vena cava,⁵ superior vena cava,⁶ and pulmonary artery trunk,⁷ causing bleeding in the temperature connection port⁶ and the malfunction of thermodiluation or SvO₂.⁷ Many of these events are detected postoperatively and thus require resternotomy5, 6, 7 to confirm and solve the entrapment. In our case, blood leakage to the syringe and thermistor connector was detected early during cardiopulmonary bypass. The thread on the removed PAC confirmed the damage. Because the blood was conclusively tracked both proximally and distally to the balloon conduit, we suspected that pulmonary air embolism might occur if we tried to re-inflate the balloon of the catheter in order to make it float and wedge it into a smaller branch of pulmonary artery. Eventually, air bubbles were noted as we inflated the balloon of the removed catheter. Bacteria-free, filtered CO₂ is the recommended inflation medium according to the manufacturer (Hospira, Lake Forest, IL, USA). However, without early detection and recognition, simply re-inflating the floating balloon could have resulted in a disastrous air embolism in our case.

This case should remind us of the possibility of entrapment by suture or knotting. The overall prevalence of PAC entrapment was 0.065% (10 of 15,244 open heart surgeries in 11.5 years).⁸ Bossert et al prospectively observed four (0.1%) serious complications in 3,730 Swan-Ganz catheter placements for cardiac surgery in 2 years, including a right ventricular free wall perforation, one knotting trouble, and two pulmonary artery ruptures.² Huang et al reported a case of pulmonary artery rupture after attempting the forced removal of a PAC that had been sutured to the pulmonary artery trunk,³ which lead to hemorrhagic shock and emergent resternotomy at the bedside. The patient expired 2 days later. While PAC entrapment was suspected, either due to being sutured to the right atrium⁹ or pulmonary artery,¹⁰ it could have been revealed by TEE despite closure of the sternum, either at the surgical table or postoperatively in the intensitve care unit. Gentle withdrawal on the PAC produces invagination of right atrial wall or pulmonary artery, which resembles “tenting” on TEE10, 11 and can be confirmed by the surgeon's direct inspection and perioperative palpation. In addition, PAC entrapment by knotting is mostly encountered in the right ventricle, superior vena cava, and right atrium2, 12 on postoperative chest radiography, fluoroscopy,¹³ and TEE,¹⁴ all of which provide images of the angulation of the PAC.

Since PAC entrapment can be potentially life-threatening upon forced removal, early recognition during cardiac surgery is imperative. The following steps may reduce the risk of devastating complicaions. First, withdraw the PAC to a proper length (usually <30 cm) after measuring the pulmonary capillary wedge pressure under TEE guidance,¹⁵ as suggested before the initiation of atrial cannulation for cardiopulmonary bypass. Second, once the stitch runs through the PAC lumen, malfunction of the modules may occur. Sudden deformation of the waveforms, inability to measure cardiac output, inability to inflate the balloon for measuring the wedging pressure, and blood leaking into the connection modules or syringe are circumstantial evidence indicative of the possibility of PAC being ensnared. Third, gentle traction of the catheter before closing the sternum is recommanded. If resistance occurs, forced withdrawl should be avoided. TEE can provide an immediate and accurate diagnosis because it will show an echogenic spot with acoustic shadowing on the suture site of the PAC and configuration-resembling “tenting” in on manual traction. Fourth, postoperative chest radiography and fluoroscopy can provide information about PACs that are entrapped by knotting or suturing by showing the angulation of the PAC. TEE may not be acceptable if the patient is uncoopertive.

In conclusion, the recognition of blood leakage from the PAC should raise awareness of potential PAC entrapment by inadvertent suturing or other mechanisms. If resistance is encountered upon withdrawal or if PAC malfunction occurs, TEE can be a reliable diagnostic tool for detecting the entrapped PAC during cardiac surgery.