Point-of-Care Ultrasound for Guiding Pulmonary Artery Catheter Placement

Graphical abstract

Highlights

• •PACs remain important for some critically ill patients.
• •PAC placement is challenging in some without fluoroscopy or TEE.
• •POCUS is ubiquitous in the ICU setting.
• •A single-operator POCUS technique for PAC placement is proposed.
• •Such a technique avoids the need for fluoroscopy or TEE.

Introduction

In critical care, bedside clinicians often use point-of-care ultrasound (POCUS) as an adjunct for active management. Advantages of POCUS include its ready availability at the bedside, real-time noninvasive imaging capability, and documentability in terms of image recording. Authors have described pulmonary artery catheter (PAC) placement in the medical literature using transesophageal echocardiography (TEE)¹ and transthoracic echocardiography.2, 3, 4, 5 However, none of these approaches has been described being performed solely from the head, where typical PAC insertion occurs via the right jugular vein. A potential benefit of real-time ultrasound is its utility in rapidly identifying PAC complications such as cardiac perforation or damage to valve apparatuses. The following is a description of a single-operator protocol described in use at a tertiary referral adult congenital heart disease treatment center in the intensive care unit.

Case Presentation

The patient was a pregnant 28-year-old woman with heart failure with reduced left ventricular ejection fraction (EF) of 20% determined using Simpson’s biplane methodology, presenting at 23 weeks’ gestation with preeclampsia and worsening respiratory distress (Video 1). The patient was emergently intubated for flash pulmonary edema and underwent emergency cesarean section. The patient received milrinone, nicardipine, and diuresis as interventions for heart failure with reduced EF. Given concerns about heart failure management at the time of pregnancy, specifically regarding increased total body fluid content and recovery from preeclamptic hypertension, clinicians decided that a PAC was necessary. Fluoroscopy and TEE were not immediately available. After sedation, vascular access was obtained in the right internal jugular vein with an 8-Fr multiaccess central venous catheter, and a 7.5-Fr PAC prepared to the manufacturer’s specification was inserted and guided using pressure waveforms and catheter distance at the bedside. The catheter was inserted to 75 cm and would not wedge for pulmonary capillary wedge pressure determination. Chest radiography revealed looping of the catheter in the right ventricle as well as at the pulmonary artery (PA) bifurcation (Figure 1).

Figure 1.

Chest radiography in the setting of an unobtainable wedge pressure, anterior-posterior projection, demonstrates the dilated heart silhouette, pulmonary infiltrates, endotracheal tube, and PAC looped within the right ventricle and PA.

Using a POCUS ultrasound platform, a cardiac POCUS–certified intensivist obtained views of the heart and PA bifurcation. The intensivist retracted the catheter to 30 cm, at which point the tip appeared unlooped in the right atrium using the right ventricular inflow view with a widened sector to 135° (Figure 2; Video 2). Using the parasternal short-axis view at the level of the aortic valve (AoV), the operator advanced the catheter while sweeping the transducer toward the AoV level following its tip (Figure 3; Video 3). The PA appeared large in these views and facilitated imaging of the PAC. As the catheter engaged the pulmonary valve (PV), it was apparent that the balloon of the PAC could not pass through the PV annulus (Figure 4; Video 4). Resistance to advancement at this point in the initial pass likely contributed to looping of the catheter in the right ventricle. The operator partially deflated the balloon, and the catheter gently passed through the open PV at approximately 50 cm. This occurred under direct visualization to avoid injury from the catheter tip. Once it cleared the valve, the balloon was reinflated (Figure 5; Video 5). The PAC was advanced to the PA bifurcation at approximately 55 cm and area was visualized using the PA view obtained by rocking the probe to aim slightly laterally and cephalad from the parasternal short-axis view to align with the main PA and left and right PAs (Figure 6; Video 6). The operator advanced the catheter again into the left PA, and wedging was not possible at 75-cm insertion. This was concerning for PA anatomy such as branching or other reasons causing an ellipsoid vessel cross-section preventing wedging. The operator withdrew the catheter to 55 cm and again visualized the tip at the PA bifurcation. The tip of the catheter was rotated with gentle torque on the catheter and redirected into the right PA (Figure 7; Video 7). From there it was advanced and wedged at 63 cm. Successful placement of a PAC in the right PA was confirmed on chest radiography (Figure 8). The patient received sedation during the procedure and did not experience any discomfort. Although the PAs subjectively looked large on ultrasound, the main PA pressures were approximately 30/10 mm Hg, with pulmonary capillary wedge pressures of 10 to 12 mm Hg, and the PA dimensions may have reflected the patient’s overall intravascular volume status and mechanical ventilation requirement. Within 3 days and treatment with milrinone and targeted diuresis and afterload management for pulmonary capillary wedge pressures, weaning milrinone off occurred with discontinuation of the PAC. The patient remained in hospital care for several weeks for heart failure and postpartum management and had a left ventricular EF of 37% at the time of discharge.

Figure 2.

POCUS, parasternal long-axis right ventricular inflow diastolic (left) and systolic (right) views, demonstrates the PAC (asterisk) entering the right atrium (RA) via the superior vena cava, with the tip positioned proximal to the tricuspid valve (TV) annulus. RV, Right ventricle.

Figure 3.

POCUS, basal parasternal short-axis diastolic (left) and systolic (right) views, demonstrates the PAC (asterisk) within the right atrium (RA). LA, Left atrium.

Figure 4.

POCUS, parasternal long-axis, right ventricular outflow tract diastolic view, demonstrates the PAC (asterisk) impasse at the PV and unable to pass into the dilated PA.

Figure 5.

POCUS, parasternal long-axis, right ventricular outflow tract diastolic view, demonstrates successful PAC (asterisk) positioned beyond the PV and within the dilated PA following partial balloon deflation.

Figure 6.

POCUS, basal parasternal short-axis view, superiorly tilted to visualize the PA bifurcation, demonstrates the PAC (asterisk) within the proximal left PA branch.

Figure 7.

POCUS, basal parasternal short-axis view, superiorly tilted to visualize the PA bifurcation, demonstrates redirection of the PAC (asterisk) within the proximal right PA branch.

Figure 8.

Chest radiography in the setting of an obtainable wedge pressure, anterior-posterior projection, demonstrates the dilated heart silhouette, pulmonary infiltrates, endotracheal tube and the PAC unlooped within the right ventricle and PA.

Discussion

PACs are a mainstay of hemodynamic assessment and monitoring in critical and perioperative clinical environments. Insertion of these catheters into the PA without fluoroscopy or TEE requires skill and recognition of catheter tip pressure data during insertion. Ultimately PACs are essential for managing critically ill patients with elevated left atrial pressures.⁶ Placement success varies by center⁷ and patient population,⁸ though studies describe success rates of 25% to 75%⁹ in control populations using pressure and catheter length for placement. Although fluoroscopy is more definitive for catheter location, it exposes patients and clinicians to ionizing radiation¹⁰ and requires specialized operator training and facilities. The use of TEE is also common in the cardiac surgical environment but is subject to probe and operator availability. POCUS permits real-time guidance of difficult-to-place PACs in critically ill patients in an expedient manner, especially when fluoroscopy and TEE are not readily available.

The protocol (Figure 9) occurs after the insertion of an introducer sheath for pulmonary catheter access into a large upper extremity vessel and has been performed both in endotracheal intubated and nonintubated patients. This methodology can be a primary catheter insertion strategy or used when conventional insertion has failed.

• 1.Sterile draping of the patient should leave fenestrated access to the introducer sheath as well as the chest (Figure 10). Alternatively, the procedure is performed without sterile draping after securing the catheter in a sterile sheath.
• 2.Position the PAC in the introducer sheath, transducing a distal tip pressure in the superior vena cava.
• 3.Inflate the PAC balloon. Obtain the right ventricular inflow view with the ultrasound probe in the parasternal window. Advance the PAC such that it reads a right atrial pressure and appears in the right atrium.
• 4.Rotate the ultrasound view into the parasternal short-axis view at the level of the AoV. Advance the catheter into the right ventricular outflow tract. If the tip does not engage the tract, rotate the catheter under visualization such that it does with ongoing advancement.
• 5.Advance the catheter through the PV into the main PA. If it does not pass, carefully partially deflate it to fit under direct visualization. The catheter pressure tracing will change from a right ventricular to a PA waveform as the PAC passes the PV.
• 6.Move the ultrasound probe laterally, visualizing the main PA and branch PA bifurcation. View the PAC as it is advanced into a branch PA.
• 7.If wedging the catheter is a goal but not possible in the branch PA it resides in, retract the catheter back to the PA bifurcation and rotate it into position such that it engages and wedges in the other branch PA.

Figure 9.

Serial illustration of the right ventricular inflow tract (A), basal parasternal short-axis view at the AoV level (B), and superiorly tilted view to visualize the PA bifurcation (C), demonstrates the protocol for POCUS-guided insertion of a PAC. aAo, Ascending aorta; dAo, descending aorta; IVC, inferior vena cava; LPA, left PA; MPA, main PA; RPA, right PA.

Figure 10.

Photograph obtained during POCUS-guided placement of a PAC demonstrates the patient, operator, and ultrasound system positioning.

Guidance of PAC placement has been described in case reports as early as 1986,^3,11 though details on how the imaging was performed were lacking. In a series of nine neonates who underwent PAC placement at the bedside using echocardiographic guidance, Yoshizato and Hagler² described an approach via femoral venous access, but operator position and details regarding ultrasound were not described. A two-operator technique was described by Josan et al.,⁴ starting from the subcostal four-chamber view, which may benefit from separation of roles between PAC inserter and ultrasound operator but loses the advantage of a single operator’s understanding both PAC motion and probe placement simultaneously. Tan et al.⁵ tested the accuracy of echocardiography vs pressure waveform guidance in identifying PAC placement after insertion, with a reassuring Cohen’s κ of 0.92, but echocardiography was performed after PAC insertion and did not guide placement.

Advantages of this protocol are its performance at the head of the patient with the operator scanning left-handed, in concordance with practice in many echocardiography laboratories, while positioning the catheter and inflating and deflating the PA balloon with the right hand. For this patient, the partially deflated PA catheter balloon was continually monitored using ultrasound until reinflation past the PV. An advantage is that complications such as catheter malposition and perforation of cardiac structures can be visualized early during the procedure, as opposed to when patients become symptomatic or undergo their placement confirmation chest radiographic examination. Additionally, recognition of tricuspid regurgitation or PV regurgitation may be recognized before PAC insertion, providing information not only on patient status but on the identification of valvular function before crossing the valves with the PAC. Compared with the use of fluoroscopy, this method avoids exposure to ionizing radiation. Compared with the use of TEE, this methodology is readily available with basic ultrasound machines, and endotracheal intubation is not necessary, as it is in some patients undergoing TEE.

Disadvantages of this protocol could include that surgical sites or habitus can obscure windows for this assessment. Handedness issues may also interfere if an operator only scans with their right hand, though the methodology is analogous to other procedures requiring procedural manipulation with one hand and ultrasound scanning with the other. An operator must consider the practicalities of scanning from the head of the patient in terms of reversing the direction of sweeps and fanning compared with scanning from the side of a patient. Given that sites may vary, left femoral catheterization is potentially difficult for an operator using these steps without scanning with the right hand and operating the PAC with the left, but visualization is possible with this method at other sites in the right femoral and both internal jugular and subclavian veins.

Recent advances in ultrasound technology, such as high-resolution transducers, have significantly enhanced the success rate and safety of PA catheterization. Studies have shown that real-time ultrasound guidance reduces malposition complications with other long device placements (peripherally inserted central catheter, umbilical venous catheter) compared with traditional blind techniques. Additionally, dynamically monitoring catheter trajectory minimizes the risk for arrhythmias and other catheter-associated complications. These advances could make ultrasound-guided procedures increasingly accessible, even in resource-limited settings where fluoroscopy or TEE may not be an option.

Conclusion

Catheter placement and visualization can be performed with a single operator as described in our case. With improvement in ultrasound technology, these procedures can be performed with ultrasound technology readily available at the bedside. Further investigation is necessary in elucidating whether these methods improve procedure success and patient safety.

Ethics Statement

The authors declare that the work described has been carried out in accordance with The Code of Ethics of the World Medical Association (Declaration of Helsinki) for experiments involving humans.

Consent Statement

The authors declare that since this was a non-interventional, retrospective, observational study utilizing de-identified data, informed consent was not required from the patient under an IRB exemption status.

Funding Statement

The authors declare that this report did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Disclosure Statement

Dr. Su has received speaking and lecture fees and travel reimbursement from The University of Texas Health Science Center at San Antonio, Stanford University School of Medicine, and the Society of Critical Care Medicine; and has received speaking and lecture fees from the American Academy of Pediatrics.

Supplementary Data

Video 1

Two-dimensional transthoracic echocardiography, apical four-chamber baseline view, demonstrates severely dilated, globular left ventricle with severe systolic dysfunction and normal right heart.

Video 2

POCUS, parasternal long-axis, right ventricular inflow view, demonstrates the PAC (asterisk) entering the right atrium via the superior vena cava with the tip positioned proximal to the tricuspid valve annulus.

Video 3

POCUS, basal parasternal short-axis view, demonstrates the PAC (asterisk) within the right atrium.

Video 4

POCUS, parasternal long-axis, right ventricular outflow tract view, demonstrates the PAC (asterisk) impasse at the PV and unable to pass into the dilated PA.

Video 5

POCUS, parasternal long-axis, right ventricular outflow tract view, demonstrates successful PAC (asterisk) positioned beyond the PV and within the dilated PA following partial balloon deflation.

Video 6

POCUS, basal parasternal short-axis view, superiorly tilted to visualize the PA bifurcation, demonstrates the PAC (asterisk) within the proximal left PA branch.

Video 7

POCUS, basal parasternal short-axis view, superiorly tilted to visualize the PA bifurcation, demonstrates redirection of the PAC (asterisk) within the proximal right PA branch.